KR102732041B1 - Electrostatic Device And The Operating Method Of The Same - Google Patents

Abstract

An electrostatic device according to one embodiment of the present invention comprises: an electrostatic electrode layer; first and second dielectric layers sequentially arranged on the electrostatic electrode layer; and a power source that applies a voltage to the electrostatic electrode layer. The power source applies a first voltage to adsorb a substrate on the second dielectric layer and accumulate a first interface charge between the first dielectric layer and the second dielectric layer. The power source applies a second voltage of an opposite polarity to the first voltage to accumulate an interface charge of an opposite polarity to the first interface charge, thereby adsorbing the substrate.

Description

Electrostatic Device And The Operating Method Of The Same

The present invention relates to an electrostatic device, and more particularly, to an electrostatic device and an operating method thereof.

An electrostatic chuck is a device that uses electrostatic force generated by a difference in electrical potential to hold a substrate in place.

Electrostatic chucks are mainly used in substrate handling equipment and transport devices.

The problem to be solved by the present invention is to provide an electrostatic device that maximizes electrostatic force by a difference in dielectric constant.

The problem to be solved by the present invention is to provide an electrostatic device that maximizes electrostatic force by a difference in electrical conductivity.

An object of the present invention is to provide an electrostatic device that minimizes interfacial charges.

An electrostatic device according to one embodiment of the present invention comprises: an electrostatic electrode layer; first and second dielectric layers sequentially arranged on the electrostatic electrode layer; and a power source that applies a voltage to the electrostatic electrode layer. The power source applies a first voltage to adsorb a substrate on the second dielectric layer and accumulate a first interface charge between the first dielectric layer and the second dielectric layer. The power source applies a second voltage of an opposite polarity to the first voltage to accumulate an interface charge of an opposite polarity to the first interface charge, thereby adsorbing the substrate.

In one embodiment of the present invention, the first voltage and the second voltage are alternately repeated, the application time of the first voltage is shorter than the time constant of the first interface charge, and the application time of the first voltage can be the same as the application time of the second voltage.

An electrostatic device according to one embodiment of the present invention comprises: an electrostatic electrode layer; and first and second dielectric layers sequentially arranged on the electrostatic electrode layer; and a power source that applies a voltage to the electrostatic electrode layer. An operating method of the electrostatic device comprises: a step of applying a first voltage to the power source to adsorb a substrate on the second dielectric layer and accumulate a first interface charge between the first dielectric layer and the second dielectric layer; and a step of applying a second voltage having an opposite polarity to the first voltage to erase the first interface charge accumulated between the first dielectric layer and the second dielectric layer into a charge having an opposite polarity.

In one embodiment of the present invention, the second dielectric layer may be an air gap.

In one embodiment of the present invention, the first voltage and the second voltage are alternately repeated, and the application time of the first voltage may be shorter than the time constant of the first interface charge.

In one embodiment of the present invention, the application time of the first voltage may be the same as the application time of the second voltage, and the time constant of the first interface charge may be 10 seconds or more.

In one embodiment of the present invention, at the first voltage, the substrate is charged with a first charge, and the first interface charge can be charged with a charge having the same sign as the first charge.

An electrostatic device according to one embodiment of the present invention comprises: an electrostatic electrode layer; and a first dielectric layer and a second dielectric layer sequentially arranged on the electrostatic electrode layer; and a power source that applies a voltage to the electrostatic electrode layer. An operating method of the electrostatic device comprises: a step of applying a first voltage to the power source to adsorb a substrate and accumulate a first interface charge between the first dielectric layer and the second dielectric layer; and a step of applying a second voltage having an opposite polarity to the first voltage to accumulate an interface charge having an opposite polarity to the first interface charge, thereby adsorbing the substrate.

In one embodiment of the present invention, the application time of the first voltage may be shorter than the time constant of the first interface charge.

In one embodiment of the present invention, the application time of the first voltage may be the same as the application time of the second voltage, and the time constant of the first interface charge may be 10 seconds or more.

In one embodiment of the present invention, the first voltage and the second voltage can be alternately repeated.

The present invention can provide an electrostatic device that maximizes electrostatic force by a difference in dielectric constant.

The present invention can provide an electrostatic device that maximizes electrostatic force by a difference in electrical conductivity.

The present invention provides an electrostatic device that minimizes interfacial charge.

Figure 1 is a conceptual diagram illustrating the basic structure of an electrostatic device according to one embodiment of the present invention.
Figure 2 shows an electric field of a second region of an electrostatic device according to one embodiment of the present invention.
Figure 3a shows an electric field of a second region of an electrostatic device according to one embodiment of the present invention.
Figure 3b shows the electric field of the second region when the dielectric constant ratio of the electrostatic device according to one embodiment of the present invention is 0.1.
Figure 4 shows an electric field of a second region of an electrostatic device according to one embodiment of the present invention.
Figure 5 shows an electric field of a second region of an electrostatic device according to one embodiment of the present invention.
Figure 6 shows the interface surface charge density of an electrostatic device according to one embodiment of the present invention.
Figure 7 shows the interface surface charge density of an electrostatic device according to one embodiment of the present invention.
Figure 8 shows the relaxation time (τ) of an electrostatic device according to one embodiment of the present invention.
Figure 9 shows the relaxation time (τ) of an electrostatic device according to one embodiment of the present invention.
Figure 10 shows the relaxation time (τ) of an electrostatic device according to one embodiment of the present invention.
Figure 11 shows the intensity of the electric field in the second region over time.
Figure 12 shows the intensity of the electric field in the second region over time.
Figure 13 shows the intensity of the electric field in the second region over time.
Figure 14a shows the intensity of the electric field in the second region over time.
Figure 14b shows the intensity of the electric field in the second region over time.
Figure 15 shows the intensity of the electric field in the second region over time.
Figure 16a shows the intensity of the electric field in the second region over time.
Figure 16b shows the intensity of the electric field in the second region over time.
FIG. 17 is a conceptual diagram showing a parallel connection structure of a second dielectric layer according to one embodiment of the present invention.
FIG. 18 is a conceptual diagram showing a parallel connection structure of a second genetic layer according to one embodiment of the present invention.
Figure 19 is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.
Figure 20 is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.
Figure 21 shows an electric field of an electrostatic device according to one embodiment of the present invention.
Figure 22 shows the interface surface charge density of an electrostatic device according to one embodiment of the present invention.
Figure 23 is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.
Figure 24 is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.
FIG. 25a is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.
Figure 25b is a conceptual diagram explaining the operation of the electrostatic device of Figure 25a.
Figure 25c is a conceptual diagram explaining the operation of the electrostatic device of Figure 25a.
Figure 25d is a conceptual diagram explaining the operation of the electrostatic device of Figure 25a.
Figure 26 is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.
Figure 26 is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.
Figure 27 is a conceptual diagram explaining the structure of an electrostatic device according to one embodiment of the present invention.
Figure 28 is a conceptual diagram explaining the structure of an electrostatic device according to one embodiment of the present invention.
Figure 29 is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.
Figure 30 is a conceptual diagram illustrating a typical electrostatic device.
Figures 31 to 33 are conceptual diagrams illustrating an electrostatic device according to one embodiment of the present invention.
Figures 34 to 36 are conceptual diagrams illustrating an electrostatic device according to one embodiment of the present invention.
Figures 37 to 44 are conceptual diagrams illustrating an electrostatic device according to one embodiment of the present invention.
Figure 45 is a conceptual diagram showing an electrostatic device according to one embodiment of the present invention.
Figure 46 is a conceptual diagram showing an electrostatic device according to one embodiment of the present invention.

The present invention provides an electrostatic device that increases electrostatic force, changes interface charge density, and controls relaxation time. The substrate or the adsorbate may be a semiconductor substrate, a glass substrate, a plastic substrate, or a metal substrate. The dielectric substrate may have a conductive layer coated on one surface. In the present invention, the air gap includes air at atmospheric pressure, gas at low pressure, and an extremely vacuum state.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed contents can be thorough and complete, and so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art. In the drawings, components are exaggerated for clarity. Parts denoted by the same reference numerals throughout the specification represent the same components.

The operating principle of a two-layer electrostatic device according to one embodiment of the present invention is described.

Figure 1 is a conceptual diagram illustrating the basic structure of an electrostatic device according to one embodiment of the present invention.

Referring to FIG. 1, a first dielectric layer (122) and a second dielectric layer (124) are laminated between a first electrode (110) and a second electrode (120).

The first region is formed of a first dielectric layer (122), has a first permittivity (ε1) and a first electrical conductivity (σ1), and has a thickness of d1. The second region is formed of a second dielectric layer (124), has a second permittivity (ε2) and a second electrical conductivity (σ2), and has a thickness of d2.

A power source (130) can apply a voltage between the first electrode and the second electrode. The power source can be a DC power source, a DC pulse power source, an AC power source, or a DC biased AC power source.

The first electrode (110) is an electrostatic electrode for providing electrostatic force, and the second electrode (120) may be a substrate, a conductive adsorbate, or a conductive layer coated on an adsorbate. The first electrode (110) may be a conductor or a semiconductor. The second electrode (120) may be a conductive substrate or a semiconductor substrate. The conductive layer may be a conductor or a semiconductor.

If the first electrical conductivity (σ1) and the second electrical conductivity (σ2) are neglected, the electric fields (E1, E2) in the first and second regions are given as follows.

[Mathematical Formula 1]

Here, V ₀ is the potential difference applied between the first electrode (110) and the second electrode (120).

The electrostatic pressure (f) of the second electrode by the second region is given as follows.

[Mathematical formula 2]

Considering the first electrical conductivity (σ1) and the second electrical conductivity (σ2), using Maxwell's equations and the continuity equation, the electric field in the first region (E1) and the electric field in the second region (E2) are given as follows in steady state.

[Mathematical Formula 3]

The surface charge density (ρ _si ) at the interface between the first and second regions is given as follows in steady state.

[Mathematical Formula 4]

In the second region, the electrostatic pressure (f) of the second electrode is given as follows. That is, the electrostatic pressure of the second electrode is given as follows.

[Mathematical Formula 5]

The electric field (E1) in the first region and the electric field (E2) in the second region are given as follows depending on time (t) in the transient state.

[Mathematical Formula 6]

That is, the electric field is given by the permittivity in the initial state, and is determined by the permittivity and surface charge density in the transition state, and the electric field is given only by the electrical conductivity in the steady state.

The interfacial surface charge density (ρ _si ) in the transient state is given by:

[Mathematical formula 7]

Here, τ is the relaxation time or time constant.

[Temperature dependence of permittivity]

The permittivity of a dielectric can increase with temperature. As the permittivity changes with temperature, the electric field changes, and the electrostatic force can change with temperature.

[Temperature dependence of resistivity]

The resistivity of a dielectric can decrease with temperature. The electrostatic force can change with temperature.

[Changes in resistivity according to composition]

For example, alumina is formed by adding TiO2, and the resistivity can change depending on the addition ratio of TiO2. The first dielectric layer (122) can be a high-k dielectric such as alumina, and the second dielectric layer (124) can be a low-k dielectric such as an air gap.

The above first dielectric layer (122) may include at least one of aluminum oxide, aluminum nitride, magnesium oxide, iridium oxide, tantalum oxide, hafnium oxide (HfO2), zirconium oxide (ZrO2), barium oxide, and titanium oxide.

The second dielectric layer (124) has a second permittivity. The second dielectric layer (124) may be a low-permittivity material. The second dielectric layer may include at least one of a vacuum layer, a gas layer, an air layer, silicon oxide, silicon nitride, silicon oxynitride, polyimide, poly(arylene ether) (PAE), a cyclobutane derivative, polysilsesquioxane, fluorinated amorphous carbon, Xorogel, and a nanoporous organosilicate.

[Electric field in the second region according to the dielectric constant ratio when the resistivity is ignored]

Figure 2 shows an electric field of a second region of an electrostatic device according to one embodiment of the present invention.

Referring to FIG. 2, the total thickness (d) is 10 um, and the second electric field (E2) of the second region is displayed according to the dielectric constant ratio (ε2/ε1) for the thickness (d2) of the second dielectric layer (124) of 1 um, 2 um, and 5 um. When the dielectric constant ratio (ε2/ε1) is 0.5 or less, the second electric field (E2) of the second region increases rapidly. As the thickness (d2) of the second dielectric layer (124) decreases and the dielectric constant ratio (ε2/ε1) decreases, the intensity of the second electric field (E2) increases. Accordingly, the electrostatic force increases. In order to maximize the dielectric constant ratio, the second dielectric layer (124) may be air or a vacuum.

[Electric field in the second region according to the thickness of the second dielectric layer when the resistivity is ignored]

Figure 3 shows an electric field of a second region of an electrostatic device according to one embodiment of the present invention.

Referring to FIG. 3, when the permittivity ratio (ε2/ε1) is 0.01, 0.1, 0.2, and 0.5, the intensity of the second electric field (E2) according to the thickness (d2) of the second dielectric layer is displayed. When the thickness ratio (d2/d) of the second dielectric layer is 0.4 or less (4 um when the total thickness is 10 um), the intensity of the electric field (E2) of the second region increases rapidly. Preferably, the thickness ratio (d2/d) of the second dielectric layer may be 0.2 or less. For example, when the permittivity ratio (ε2/ε1) is 0.1, the intensity of the electric field (E2) of the second region may increase tenfold as the thickness (d2) of the second dielectric layer decreases to 0. That is, as the thickness (d2) of the second dielectric layer decreases, the intensity of the electric field (E2) of the second region increases.

The intensity of the electric field (E2) in the second region may be less than the dielectric breakdown field. For example, when the second dielectric layer (124) is air at atmospheric pressure, the breakdown field may be about 3 MV/m.

For example, if the second dielectric layer (124) is an extreme vacuum layer, the breakdown electric field may be at the level of about 20 MV/m.

For example, when the dielectric constant ratio (ε2/ε1) is 0.1 and the second dielectric layer (124) is a vacuum layer, an electric field of 10 MV/m is required in the second region to achieve an electrostatic pressure of about 10 Torr. When the total thickness (d) is 100 um and the thickness (d2) of the second dielectric layer (124) is 10 um, a voltage of about 200 V is required.

For example, when the dielectric constant ratio (ε2/ε1) is 0.1 and the second dielectric layer is a vacuum layer, an electric field of 20 MV/m is required in the second region to achieve a constant voltage of about 40 Torr. When the total thickness is 100 um and the thickness of the second dielectric layer (d2) is 10 um, a voltage of about 285 V is required.

When the permittivity ratio (ε2/ε1) is 0.1, even when the thickness (d2) of the second dielectric layer decreases, the second electric field (E2) does not increase infinitely but converges to a constant value. Therefore, when the permittivity ratio (ε2/ε1) is 0.1 or more and the thickness ratio (d2/d) of the second dielectric layer is 0.05 or less, the second electric field (E2) is almost constant.

When the first dielectric constant (ε1) of the first dielectric layer (122) is greater than the second dielectric constant (ε2) of the second dielectric layer, and when the second dielectric layer (124) replaces a part of the first dielectric layer (122), the electrostatic force may increase compared to the case where only the first dielectric layer is formed. However, the thickness (d2) of the second dielectric layer may be equal to or less than a predetermined value with respect to the total thickness (d) given as follows.

[Mathematical formula 8]

For example, if the relative permittivity of the first dielectric layer is 10 and the relative permittivity of the second dielectric layer is 1, the thickness (d2) of the second dielectric layer may be 0.25 d.

If the electrical conductivity is ignored, it is difficult to realistically achieve a dielectric constant ratio (ε2/ε1) of 0.01 or higher. Therefore, in order to increase the strength of the second electric field (E2), the thickness of the second dielectric layer can be reduced.

Describes the characteristics when resistivity is taken into account.

[Electric field according to electrical conductivity ratio when considering resistivity]

Figure 4 shows an electric field of a second region of an electrostatic device according to one embodiment of the present invention.

Referring to FIG. 4, the first dielectric layer (122) has a first permittivity (ε1) and a first electrical conductivity (σ1), and the second dielectric layer (124) has a second permittivity (ε2) and a second electrical conductivity (σ2). In a steady state, the electric field (E2) of the second region does not depend on the permittivity but only on the electrical conductivity.

The total thickness (d) is 10 um, and the electric field (E2) of the second dielectric layer is expressed according to the electric conductivity ratio (σ2/σ1) for the thickness (d2) of the second dielectric of 1 um, 2 um, and 5 um. When the permittivity ratio (ε2/ε1) is 0.1, the electric field of the second region increases rapidly when the electric conductivity ratio (σ2/σ1) is 0.5 or less. As the thickness of the second dielectric layer decreases and the electric conductivity ratio (σ2/σ1) decreases, the intensity of the second electric field (E2) increases. Accordingly, the electrostatic force increases.

When an external voltage is applied between the first electrode and the second electrode, the initial second electric field is determined by the permittivity (dielectric constant ratio = 0.1) at point A. Afterwards, due to the electric conductivity ratio (σ2/σ1 = 1,000) caused by the first dielectric layer and the second dielectric layer, the second electric field (E2) reaches a steady state and reaches a new electric field (E2) at point A'. Therefore, in order to use a high second electric field, it is desirable that the relaxation time be sufficiently large.

In the normal state, in order to increase the second electric field (E2), the electric conductivity ratio (σ2/σ1) may be 0.5 or less. Preferably, the electric conductivity ratio (σ2/σ1) may be 0.1 or less.

Meanwhile, when the electrical conductivity ratio (σ2/σ1) is as small as 0.1 or less, it is desirable that the relaxation time be sufficiently small in order to use a high second electric field.

[Electric field according to thickness when considering resistivity]

Figure 5 shows an electric field of a second region of an electrostatic device according to one embodiment of the present invention.

Referring to FIG. 5, when the electric conductivity ratio (σ2/σ1) is 0.01, 0.1, 0.2, and 0.5, the intensity of the second electric field (E2) according to the thickness (d2) of the second dielectric layer (124) is displayed. The dielectric constant ratio (ε2/ε1) is 0.1. When the thickness ratio (d2/d) of the second dielectric layer (124) is 0.4 (the total thickness (d) is 10 um, d2=4 um) or less, the intensity of the electric field (E2) of the second region increases rapidly. Preferably, the thickness ratio (d2/d) of the second dielectric may be 0.2 (2 um) or less.

For example, when the electrical conductivity ratio (σ2/σ1) is 0.1, the intensity of the electric field (E2) in the second region can increase by a factor of 10 as the thickness (d2) of the second dielectric decreases to 0. However, when the electrical conductivity ratio (σ2/σ1) is 0.1, the intensity of the electric field does not change significantly when the thickness ratio (d2/d) of the second dielectric is 0.05 or less.

The electrical conductivity ratio (σ2/σ1) can be easily achieved at 0.1 or less. For example, if an impurity is added to the first dielectric layer, the electrical conductivity of the first dielectric layer can change.

For example, when the electrical conductivity ratio (σ2/σ1) is 0.01, the intensity of the electric field changes significantly when the thickness ratio (d2/d) of the second dielectric is 0.05 or less.

Point A is the intensity of the electric field determined by the permittivity ratio (0.1) immediately after the external voltage is applied. Point A' is the intensity of the electric field determined by the electric conductivity ratio in the steady state. The time from the initial state (A) to the steady state (A') is determined by the relaxation time. The relaxation time can be within several seconds. Preferably, it can be within several hundred milliseconds.

The second dielectric layer (124) is an air gap (or vacuum gap), and the thickness (d2) of the air gap can be 0.01 to 0.2 with respect to the total thickness of the first dielectric layer and the air gap.

When a high electric field (or electrostatic power) is to be obtained by using the electric conductivity ratio (σ2/σ1), the electric conductivity ratio (σ2/σ1) may be less than or equal to the permittivity ratio. In addition, the thickness ratio (d2/d) of the second dielectric layer may be less than or equal to 0.1.

The electrical conductivity ratio (σ2/σ1) may be 0.01 or less, and the thickness ratio (d2/d) of the second dielectric layer may be 0.1 or less. However, the intensity of the second electric field (E2) is very sensitive to the thickness ratio (d2/d) of the second dielectric layer. A high second electric field may exceed the dielectric breakdown field. Therefore, it may not be desirable for the thickness ratio (d2/d) of the second dielectric layer to be 0.01 or less.

[Interfacial surface charge density according to electrical conductivity ratio when considering resistivity]

Figure 6 shows the interface surface charge density of an electrostatic device according to one embodiment of the present invention.

Referring to Fig. 6, the interface surface charge density (ρ _si ) depends on the ratio of electric conductivities (σ2/σ1) in the normal state. The total thickness (d) is 10 um, and the interface surface charge density (ρ _si ) is expressed according to the electric conductivity ratio (σ2/σ1) for the thicknesses (d2) of the second dielectric layer (124) of 1 um, 2 um, and 5 um. The permittivity ratio (ε2/ε1) is 0.1.

The unit of the surface charge density (ρ _si ) of the interface is expressed as the product of the applied voltage (V) and the second permittivity of the second dielectric layer.

The first electrode is charged with a positive voltage, and the second electrode is grounded. In this case, when the electrical conductivity ratio (σ2/σ1) is 0.1 or less, the interfacial surface charge density (ρ _si ) between the first dielectric layer and the second dielectric layer rapidly increases to a positive value. On the other hand, when the electrical conductivity ratio (σ2/σ1) is 0.1 or more, the interfacial surface charge density (ρ _si ) slowly increases to a negative value.

Typically, when the second electrode is grounded and a positive voltage is applied to the first electrode, the interfacial surface charge density (ρ _si ) is known to have a positive value. However, according to the present invention, the sign of the interfacial surface charge density (ρ _si ) depends on the dielectric constant ratio and the electrical conductivity ratio.

When the electrical conductivity ratio (σ2/σ1) is 0.1 and the permittivity ratio (ε2/ε1) is 0.1, the interfacial surface charge density (ρ _si ) is zero. This condition is a condition in which no interfacial surface charge is accumulated, and can be used for rapid dechucking. In addition, since the interfacial surface charge density (ρ _si ) is zero, the second electric field (E2) does not change with time.

As the thickness (d2) of the second dielectric layer (124) decreases and the electric conductivity ratio (σ2/σ1) decreases, the interfacial surface charge density (ρ _si ) increases to a positive value. When the external voltage is removed, the interfacial surface charge density (ρ _si ) escapes to the outside with a characteristic time constant (or time constant or relaxation time).

According to one embodiment of the present invention, when the electrical conductivity ratio (σ2/σ1) is equal to the dielectric constant ratio (ε2/ε1), the interfacial surface charge density (ρ _si ) is zero. Therefore, the interfacial surface charge does not need to be removed separately.

Referring to FIGS. 1 and 6, the electrostatic device (10) includes: an electrostatic electrode layer (110); a first dielectric layer (122) disposed on the electrostatic electrode layer; and a second dielectric layer (124) disposed on the second dielectric layer (122). The first dielectric layer (122) has a first permittivity (ε1) and a first electrical conductivity (σ1), and the second dielectric layer (124) has a second permittivity (ε2) and a second electrical conductivity (σ2), and a ratio of the second permittivity to the first permittivity (ε2/ε1) is equal to a ratio of the second electrical conductivity to the first electrical conductivity (σ2/σ1).

The thickness (d2) of the second dielectric layer (124) may be 0.01 to 0.2 with respect to the total thickness (d) of the first dielectric layer and the second dielectric layer. That is, the thickness ratio (d2/d) may be 0.01 to 0.2. The ratio of the second electrical conductivity to the first electrical conductivity may be 0.5 or less.

Referring to FIGS. 1 and 6, an electrostatic device (10) includes an electrostatic electrode layer (110); a first dielectric layer (122) disposed on the electrostatic electrode layer; and an air gap (124) formed in the first dielectric layer. The air gap is filled with a gas, the first dielectric layer (122) has a first permittivity (ε1) and a first electrical conductivity (σ1), the gas has a second permittivity (ε2) and a second electrical conductivity (σ2), and a ratio of the second permittivity to the first permittivity (ε2/ε1) is equal to a ratio of the second electrical conductivity to the first electrical conductivity (σ2/σ1).

The thickness of the air gap may be 0.01 to 0.2 with respect to the total thickness of the first dielectric layer and the air gap. The ratio of the second electrical conductivity to the first electrical conductivity may be 0.5 or less.

Referring to FIGS. 1 and 6, an electrostatic device (10) includes: an electrostatic electrode layer (110); and a first dielectric layer (122) disposed on the electrostatic electrode layer; a substrate (120) disposed on the first dielectric layer; and a second dielectric layer (124) disposed between a lower surface of the substrate and the first dielectric layer. The first dielectric layer has a first permittivity (ε1) and a first electrical conductivity (σ1), the second dielectric layer has a second permittivity (ε2) and a second electrical conductivity (σ2), and a ratio of the second permittivity to the first permittivity (ε2/ε1) is equal to a ratio of the second electrical conductivity to the first electrical conductivity (σ2/σ1).

The thickness (d2) of the second dielectric layer may be 0.01 to 0.2 with respect to the total thickness (d) of the first dielectric layer and the second dielectric layer. The ratio (σ2/σ1) of the second electrical conductivity to the first electrical conductivity may be 0.5 or less.

[Interfacial charge as a function of thickness when considering resistivity]

Figure 7 shows the interface surface charge density of an electrostatic device according to one embodiment of the present invention.

Referring to Fig. 7, the interface surface charge density (ρ _si ) according to the thickness (d2) of the second dielectric layer (124) is shown when the electric conductivity ratio (σ2/σ1) is 0.01, 0.1, 0.2, and 10. The dielectric constant ratio (ε2/ε1) is 0.1.

When the electrical conductivity ratio (σ2/σ1) is 0.01 (i.e., smaller than the permittivity ratio (ε2/ε1)) and the thickness ratio (d2/d) of the second dielectric is 0.4 (4 μm) or less, the interfacial surface charge density (ρ _si ) increases rapidly as the thickness (d2) of the second dielectric decreases.

When the electrical conductivity ratio (σ2/σ1) is 0.1 (i.e., equal to the permittivity ratio), the interfacial surface charge density (ρ _si ) is zero. When the interfacial surface charge density (ρ _si ) is zero, there is no residual interfacial surface charge density even when the external voltage is removed. Therefore, there is no charge to escape from the interface.

When the electrical conductivity ratio (σ2/σ1) is 0.2 (i.e., greater than the permittivity ratio), the interfacial surface charge density (ρ _si ) has a negative value.

The thickness (d2) of the second dielectric layer may be 0.01 to 0.2 with respect to the total thickness (d) of the first dielectric layer and the second dielectric layer.

[Relaxation time according to the resistivity ratio (ρ2/ρ1 = σ1/σ2) when considering resistivity]

Figure 8 shows the relaxation time (τ) of an electrostatic device according to one embodiment of the present invention.

Referring to FIG. 8, the total thickness (d) is 10 um, and the relaxation time (or time constant, τ) according to the resistivity ratio (ρ2/ρ1 = σ1/σ2) is displayed for the thickness (d2) of the second dielectric layer (124) of 1 um. The permittivity ratio (ε2/ε1) is 0.1. As the permittivity ratio (ε2/ε1) decreases, the relaxation time decreases. In addition, the relaxation time decreases as the resistivity ratio (ρ2/ρ1) increases. The unit of the relaxation time is expressed as the product of the second permittivity (ε2) and the second resistivity (ρ2).

The relaxation time decreases as the resistivity ratio increases. In the case of the Johnson-Rahbek type having a high resistivity ratio of 10 or more, the relaxation time decreases. On the other hand, in the case of the Coulomb type having a low resistivity ratio of 10 or less, the relaxation time increases. In the case of the Johnson-Rahbek type, in order to achieve a high electric field in the steady state, the relaxation time is preferably short. On the other hand, in the case of the Coulomb type, since a low electric field is reached in the steady state, the relaxation time is preferably sufficiently long.

[Relaxation time according to thickness when considering resistivity]

Figure 9 shows the relaxation time (τ) of an electrostatic device according to one embodiment of the present invention.

Referring to Fig. 9, the relaxation time (or time constant) according to the resistivity ratio (ρ2/ρ1 = σ1/σ2) is shown. The permittivity ratio (ε2/ε1) is fixed at 0.1. As the resistivity ratio (ρ2/ρ1) increases, the relaxation time decreases.

When the resistivity ratio (ρ2/ρ1) is 10 (the electrical conductivity ratio is 0.1), the relaxation time (τ) is a constant and does not depend on the thickness (d2) of the second dielectric.

When the resistivity ratio (ρ2/ρ1) is less than 10, the relaxation time (τ) increases with the thickness (d2) of the second dielectric.

When the resistivity ratio (ρ2/ρ1) exceeds 10, the relaxation time (τ) decreases with the thickness (d2) of the second dielectric.

When the ratio of electrical conductivities (σ2/σ1) decreases to 0.1 or less (Johnson-Rahbek type), the relaxation time decreases and the interface charge density increases. In addition, the intensity of the second electric field (E2) increases. The relaxation time depends on the second resistivity and the second permittivity of the second dielectric layer. For example, in the region X of Fig. 9, when the relaxation time is considered, the ratio of the thicknesses of the second dielectric layer (d2/d) can be 0.01 to 0.1 in order to reduce the relaxation time.

When the ratio of electric conductivities (σ2/σ1) increases to 0.1 or more (clone type), the relaxation time increases and the interface charge density increases to a negative value. In addition, the intensity of the second electric field (E2) decreases over time. Therefore, in order to maintain a high electric field in the initial state, the relaxation time is preferably sufficiently long. The relaxation time depends on the second resistivity and the second permittivity of the second dielectric layer. For example, in the region Y of Fig. 9, when the relaxation time and the intensity of the second electric field are considered, the thickness ratio (d2/d) of the second dielectric layer may be 0.01 or more. Preferably, the thickness ratio (d2/d) of the second dielectric layer may be 0.01 to 0.1. However, when the relaxation time is too long, the interface charge may not be eliminated upon detachment. Accordingly, an appropriate thickness ratio may be selected for an appropriate level of relaxation time.

If a high resistivity material is deposited on the back surface of the substrate to be adsorbed, the relaxation time increases rapidly due to the resistivity of the deposited material. Therefore, a system having a stable relaxation time is required even when a high resistivity material is deposited on the back surface of the substrate.

For example, the ratio of the second electrical conductivity to the first electrical conductivity (σ2/σ1) may be smaller than the ratio of the second dielectric constant to the first dielectric constant (ε2/ε1). Accordingly, positive interfacial charges may be accumulated. In this case, in order to reduce the relaxation time, the ratio of the thicknesses of the second dielectric layer (d2/d) may be 0.01 to 0.1.

Meanwhile, when the ratio of the second electrical conductivity to the first electrical conductivity is 0.01 or less, the relaxation time can be reduced. In order to further reduce the relaxation time, the ratio of the thicknesses of the second dielectric layer (d2/d) can be 0.01 or more.

Meanwhile, when the electrical conductivity ratio is 0.1 or more, the relaxation time increases. In order to increase the relaxation time, the thickness ratio (d2/d) of the second dielectric layer may be 0.01 to 0.2. The thickness of the second dielectric layer may be 0.01 to 0.2 relative to the total thickness of the first dielectric layer and the second dielectric layer.

The second electrical conductivity is the reciprocal of the second resistivity, and the second resistivity can be less than or equal to 10^12 Ωm. For an air gap, the second resistivity can be from 10^10 Ωm to 10^12 Ωm, depending on the pressure and gas.

When the ratio of the second permittivity to the first permittivity is 0.1, and when the ratio of the second electrical conductivity to the first electrical conductivity is 0.1 or less, positive interfacial charges are accumulated.

In conclusion, the relaxation time can be set according to the purpose. For example, in the case of a Coulomb type having an air gap as the second dielectric layer (for example, the ratio of electric conductivities (σ2/σ1) is 10 or more), the adsorption time can be set to tens of seconds or more. In this case, if the thickness ratio (d2/d) of the second dielectric layer decreases to 0.01 or less, the relaxation time decreases, so that the adsorption force decreases during the adsorption time, and unintended desorption may occur. To prevent this, the thickness ratio (d2/d) of the second dielectric layer can be set to a large value so as to have a relaxation time greater than the adsorption time.

For example, in the case of a Johnson-Rahbek type having an air gap as a second dielectric layer (for example, the ratio of electric conductivities (σ2/σ1) is 0.1 or less), if the adsorption time is tens of seconds or more, if the thickness ratio of the second dielectric layer (d2/d) decreases to 0.01 or less, the relaxation time increases, so that the intensity of the second electric field does not sufficiently increase during the adsorption time, and initial adsorption may be difficult. To prevent this, the thickness ratio of the second dielectric layer (d2/d) may be set to have a relatively large value so as to have a relaxation time smaller than the adsorption time.

[Relaxation time according to dielectric constant ratio when considering resistivity]

Figure 10 shows the relaxation time (τ) of an electrostatic device according to one embodiment of the present invention.

Referring to Fig. 10, for the same resistivity ratio (ρ2/ρ1), when the permittivity ratio (ε2/ε1) increases, the relaxation time (τ) slightly decreases. That is, the relaxation time mainly depends on the resistivity ratio (ρ2/ρ1) rather than the permittivity ratio.

[Johnson-Rahbek type time-dependent electric field]

Case I d1=9 [um] d2=1 [um] ε1=10 [ε ₀ ] ε2=1 [ε ₀ ] σ1=100 [10^(-12) /Ωm] σ2=1 [10^(-12) /Ωm]

Figure 11 shows the intensity of the electric field in the second region over time.

Referring to Fig. 11, under the condition of Case I, the electric field (E2) of the second dielectric layer (124) over time is displayed over time. Case I may be a Johnson-Rahbek type. In this case, the second electric field (E2) increases over time from an initial value (0.7). The initial value (0.7) of the second electric field (E2) may be determined by the characteristics of the dielectric. When the permittivity ratio (ε2/ε1) is 0.1, the electric conductivity ratio (σ2/σ1) is 0.01, and the thickness (d1) of the first dielectric layer = 9 um and the thickness (d2) of the second dielectric layer is 1 um, the second electric field (E2) may increase over time with a relaxation time (τ).

For example, when the permittivity ratio (ε2/ε1) is 0.1 and the electrical conductivity ratio (σ2/σ1) is 0.01 (resistivity ratio = 100), the relaxation time (τ) can be approximately 0.1 [ε2ρ2]. For example, when the second dielectric layer is a weak vacuum layer, ε2 can be ε0 (vacuum permittivity) and ρ2 can be approximately 10^12 Ωm. In this case, the relaxation time (τ) can be approximately 1 second. The second electric field (E2) can increase from 0.7 MV/m to 1.2 MV/m. In this case, the interfacial surface charge density (ρ _si ) has a positive value and accumulates at the interface.

Then, when the external voltage is removed, the interfacial surface charge density (ρ _si ) is reduced by the dielectric polarization charge (ΔP), and the positive interfacial surface charge density (ρ _si ) decays over time.

[Coulomb type electric field over time]

Case II d1=9 [um] d2=1 [um] ε1=10 [ε ₀ ] ε2=1 [ε ₀ ] σ1=0.5
σ1=10^(-4) [10^(-12) /Ωm] σ2=1 [10^(-12) /Ωm]

Figure 12 shows the intensity of the electric field in the second region over time.

Referring to FIG. 12, under the condition of Case II, the electric field (E2) of the second dielectric layer (124) over time is displayed over time. Case II may be a Coulomb type. In this case, the second electric field (E2) decreases over time from an initial value. The initial value of the second electric field (E2) may be determined by the characteristics of the dielectric. When the permittivity ratio is 0.1, the electric conductivity ratio is 0.5, and the thickness (d1) of the first dielectric is 9 um and the thickness (d2) of the second dielectric is 1 um, the second electric field (E2) may decrease over time with a relaxation time (τ).

For example, when the permittivity ratio (ε2/ε1) is 0.1 and the electrical conductivity ratio (σ2/σ1) is 0.5 (resistivity ratio = 2), the relaxation time (τ) can be about 1 [ε2ρ2]. For example, when the second dielectric is a weak vacuum layer, ε2 can be ε0 and ρ2 can be about 10^12 Ωm. In this case, the relaxation time can be about 10 seconds. The second electric field (E2) can decrease from 0.7 MV/m to 0.25 MV/m in the steady state. In this case, the interfacial surface charge density (ρ _si ) has a negative value and accumulates at the interface.

Then, when the external voltage is removed, the interfacial surface _charge density (ρ _si ) is reduced over time as the polarization charge (ΔP) due to the dielectric is removed. In addition, the absolute value of the second electric field (E2) can decrease over time with a relaxation time (τ).

[Interfacial surface charge density (ρ _si ) = 0 type electric field over time]

Case III d1=9 [um] d2=1 [um] ε1=10 [ε ₀ ] ε2=1 [ε ₀ ] σ1= 10 [10^(-12) /Ωm] σ2=1 [10^(-12) /Ωm]

Figure 13 shows the intensity of the electric field in the second region over time.

Referring to FIG. 13, under the condition of Case III, the electric field (E2) of the second dielectric layer (124) over time is displayed over time. Case III is the case where the interface surface charge density (ρ _si ) is zero. In this case, the second electric field (E2) is constant over time from the initial value. The initial value of the second electric field (E2) can be determined by the characteristics of the dielectric. When the permittivity ratio is 0.1, the electric conductivity ratio is 0.1, and the thickness (d1) of the first dielectric is 9 um and the thickness (d2) of the second dielectric is 1 um, the second electric field (E2) has a relaxation time (τ) but can be constant over time.

For example, when the permittivity ratio is 0.1 and the electrical conductivity ratio is 0.1 (resistivity ratio = 10), the relaxation time (τ) can be about 1 [ε2ρ2]. For example, when the second dielectric is a weak vacuum layer, ε2 can be ε0 and ρ2 can be about 10^12 Ωm. In this case, the relaxation time can be about 10 seconds. The second electric field (E2) can be maintained at the same value over time at 0.7 MV/m. In this case, the interface surface charge density (ρ _si ) is zero, and no charge is accumulated at the interface.

Then, when the external voltage is removed, the interfacial surface charge density (ρ _si ) is zero because the polarization charge (ΔP) due to the dielectric is removed. Also, the second electric field ( _E2 ) is zero.

[Characteristic comparison]

Normal condition Case I Case II Case III E2 1.2 [MV/m] 0.25 [MV/m] 0.7 [MV/m] ρ _si Positive value Negative value 0 τ ~0.1 [ε2ρ2 sec] ~1 [ε2ρ2 sec] ~1 [ε2ρ2 sec]

[Bipolar voltage or electric field with increasing voltage]

Figure 14a shows the intensity of the electric field in the second region over time.

Referring to Fig. 14a, under the conditions of Case I, the electric field (E2) of the second dielectric layer (124) over time is displayed over time.

When an external voltage is applied, the interfacial surface charge density (ρ _si ) has a positive value, and the electric field (E2) in the second region increases with time.

Next, when the electric field (E2) of the second region is saturated, the polarity of the external voltage is changed. In this case, the second electric field (E2) can have a negative value, and the absolute value of the second electric field (E2) increases over time. At the time when the polarity of the external applied voltage is changed, the absolute value of the second electric field (E2) has a relatively small value, and has low electrostatic force.

Figure 14b shows the intensity of the electric field in the second region over time.

Referring to Fig. 14b, under the conditions of Case I, the electric field (E2) of the second dielectric layer (124) over time is displayed over time.

When an external voltage is applied, the interfacial surface charge density (ρ _si ) has a positive value, and the electric field (E2) in the second region increases with time.

Next, when the electric field (E2) of the second region is saturated, the external voltage increases further. In this case, the second electric field (E2) increases instantaneously, and the second electric field (E2) may be greater than the discharge electric field (breakdown, BD) field. Accordingly, when the second dielectric is an air gap, discharge occurs and the interface charge is reduced by the discharge charges, and the second electric field (E2) decreases. However, the discharge may lead to an arc discharge.

Case IV d1=9.5 [um] d2=0.5 [um] ε1=10 [ε ₀ ] ε2=1 [ε ₀ ] σ1=100 [10^(-12) /Ωm] σ2=1 [10^(-12) /Ωm]

Figure 15 shows the intensity of the electric field in the second region over time.

Referring to Fig. 15, under the condition of case IV, the electric field (E2) of the second dielectric layer (124) over time is displayed over time.

When an external voltage is applied, the interfacial surface charge density (ρ _si ) has a positive value, and the electric field (E2) in the second region increases with time.

Next, when the electric field (E2) of the second region is saturated, the polarity of the external voltage is changed. In this case, the second electric field (E2) can have a positive value, the second electric field (E2) decreases, and after passing the point of zero, the absolute value of the second electric field (E2) increases over time. At the point where the polarity of the external voltage is changed, the absolute value of the second electric field (E2) has a relatively small value, and there is a time when the second electric field (E2) is zero over time.

Figure 16a shows the intensity of the electric field in the second region over time.

Referring to Fig. 16a, under the condition of case II, the electric field (E2) of the second dielectric layer (124) over time is displayed over time.

When an external voltage is applied, the interfacial surface charge density (ρ _si ) has a negative value, and the electric field (E2) in the second region decreases over time.

Next, when the electric field (E2) of the second region is saturated, the polarity of the external voltage is changed. In this case, the second electric field (E2) can have a negative value, and the absolute value of the second electric field (E2) decreases over time. At the time when the polarity of the external voltage is changed, the absolute value of the second electric field (E2) has a relatively large value, and the absolute value of the second electric field (E2) decreases over time.

Figure 16b shows the intensity of the electric field in the second region over time.

Referring to Fig. 16b, under the conditions of case II, the electric field (E2) of the second dielectric layer (124) over time is displayed over time.

When an external voltage is applied, the interfacial surface charge density (ρ _si ) has a negative value, and the electric field (E2) in the second region decreases over time.

Next, when the electric field (E2) of the second region is saturated, the external voltage increases further. In this case, the second electric field (E2) can exceed the discharge electric field (BD). Accordingly, when the second dielectric is an air gap, discharge occurs and the interface charge increases due to the discharge charges, and the second electric field (E2) decreases. However, the discharge may lead to an arc discharge. The absolute value of the interface charge increases further. However, the absolute value of the second electric field (E2) may decrease.

[Parallel connection structure of the second dielectric layer when electrical conductivity is ignored]

FIG. 17 is a conceptual diagram showing a parallel connection structure of a second dielectric layer according to one embodiment of the present invention.

Referring to Fig. 17, in the electrostatic device (10a), a first dielectric layer (122) and a second dielectric layer (124) are laminated between a first electrode (110) and a second electrode (120). The first region is formed by the first dielectric layer (122), has a first permittivity (ε1) and a first electrical conductivity (σ1), and has a thickness of d1.

The second region is formed of a plurality of second dielectrics (124, 124') having the same thickness (d2). The second region can be divided into a plurality of sections according to the permittivity (or electrical conductivity). For example, the third section has the same material properties as the first dielectric, the first section has the second main dielectric layer (124) having the second main permittivity (ε2) and the second main electrical conductivity (σ2), and has a thickness of d2. The second section has the second reserve dielectric (124') having the second reserve permittivity (ε'2) and the second reserve electrical conductivity (σ'2), and has a thickness of d2.

If the electrical conductivity is neglected, different electric fields can be obtained for each section. For example, the third section can have the lowest electric field at point C. In the first section, if the second main dielectric is an air gap, the electric field can obtain a high electric field at point A. In the second section, the second auxiliary dielectric is a silicon oxide film and can have a value smaller than the first permittivity (the permittivity of alumina). In this case, the electric field in the second section can be slightly reduced compared to the intensity of the electric field in the second main dielectric.

Finally, by connecting the second dielectric layer in parallel, the desired physical properties can be secured. That is, by eliminating the third section and using only the first and second sections, the strength of the electric field can be relatively increased.

[Parallel connection structure of the second dielectric layer when considering electrical conductivity]

FIG. 18 is a conceptual diagram showing a parallel connection structure of a second genetic layer according to one embodiment of the present invention.

Referring to Fig. 18, in the electrostatic device (10b), a first dielectric layer (122) and a second dielectric layer (124) are laminated between a first electrode (110) and a second electrode (120). The first region is formed by the first dielectric layer (122), has a first permittivity (ε1) and a first electrical conductivity (σ1), and has a thickness of d1.

The second region is formed of a plurality of second dielectrics (124, 124') having the same thickness. The second region can be divided into a plurality of sections according to electric conductivity (or permittivity). For example, the third section has the same material properties as the first dielectric, the first section has the second main dielectric layer (124) having the second main permittivity (ε2) and the second main electric conductivity (σ2), and has a thickness of d2. The second section has the second reserve dielectric (124') having the second reserve permittivity (ε'2) and the second reserve electric conductivity (σ'2), and has a thickness of d2.

When considering the electric conductivity, different electric fields can be obtained for each section. For example, the third section can have the lowest electric field at point C. In the first section, when the second main dielectric (124) is an air gap, point A can obtain a high electric field. In the second section, the second reserve dielectric (124') can have a value smaller than the first electric conductivity of the first dielectric (electrical conductivity of alumina) as a silicon oxide film. In this case, the electric field (E2') of the second section can increase more than the intensity of the electric field (E2) at point B in the second main dielectric.

Finally, by connecting the second dielectric layer in parallel, the desired physical properties can be secured. That is, the intensity of the electric field can be relatively increased or decreased for each section.

For example, the third section can have a large current flow due to its low resistance. Accordingly, the third section can be eliminated, and only the second and third sections can be used. Accordingly, the desired physical properties (increased electric field strength while reducing the total current) can be realized.

This concept can be implemented in a mixed series and parallel manner in multi-layer structures of two or more layers.

Figure 19 is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.

Referring to Fig. 19, a first dielectric layer (122) and a second dielectric layer (124) are laminated between a first electrode (110) and a second electrode (120). The first region is formed by the first dielectric layer (122), has a first dielectric constant (ε1) and a first electrical conductivity (σ1), and has a thickness of d1.

A conductive layer (129) may be placed between the first dielectric layer (122) and the second dielectric layer (124). The conductive layer (129) may be very thin compared to the first dielectric layer (122) or the second dielectric layer (122). Even when the conductive layer (129) is present, the electric field and the interface surface charge density behave the same.

The above conductive layer (129) accumulates an interface surface charge. The accumulated interface charge can be removed by connecting to ground through a switch. The above conductive layer (129) can be a semiconductor or a conductor.

A conductive layer (129) is disposed between the first dielectric layer and the second dielectric layer. The conductive layer may be a semiconductor or a conductor. The conductive layer may accumulate interface charges. The thickness of the conductive layer may be thinner than that of the second dielectric layer.

The interface charge accumulated in the above-mentioned challenge layer can be eliminated by connecting to an external ground through a switch.

Alternatively, the first dielectric layer and the second dielectric layer may receive light from a light source (150) to generate electrons and holes, and the electrons or holes may move to the conductive layer (129) to control interface charges.

Referring to FIG. 19, an electrostatic device (10c) according to one embodiment of the present invention includes an electrostatic electrode layer (110); a first dielectric layer (122) disposed on the electrostatic electrode layer; a conductive layer (129) disposed on the first dielectric layer; and an air layer (124) disposed on the conductive layer. A protrusion (not shown) formed on the first dielectric layer forms an air layer between the absorbent (120) and the first dielectric layer (122). The conductive layer is not buried in the first dielectric layer.

Referring to Fig. 27, when the conductive layer is buried in the first dielectric layer or covered by another dielectric, another interfacial charge is generated. Therefore, the conductive layer can be exposed to the air gap.

The conductive layer (129) can be selectively connected to ground through a switch. The conductive layer (129) can be electrically connected to a conductive material coated on the inside of a conduit (not shown) that provides cooling gas to the air layer. The conductive layer can be a semiconductor or a metal. The conductive layer can be a photoresistive layer that receives light and has conductivity and can be CdS.

Referring to FIG. 19, an electrostatic device (10c) according to an embodiment of the present invention includes an electrostatic electrode layer (110); a dielectric layer (122) disposed on the electrostatic electrode layer; a protrusion (not shown) and a recessed portion (124) formed on the dielectric layer; and a conductive layer (129) formed on a lower surface of the recessed portion. The power source (130) includes a step of applying a first voltage to adsorb a substrate (or electrostatic electrode layer) on the dielectric layer; and a step of removing the first voltage and then grounding the conductive layer (129) to remove interface charges accumulated in the conductive layer (129), thereby detaching the substrate (or electrostatic electrode layer). The step of applying a second voltage having an opposite polarity to the first voltage to remove interface charges may be further included.

[Electric field according to temperature control (heating means)]

Figure 20 is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.

Figure 21 shows an electric field of an electrostatic device according to one embodiment of the present invention.

Figure 22 shows the interface surface charge density of an electrostatic device according to one embodiment of the present invention.

Referring to FIGS. 20 to 22, a first dielectric layer (122) and a second dielectric layer (124) are laminated between a first electrode (110) and a second electrode (120). A first region is formed by a first dielectric layer (122), has a first permittivity (ε1) and a first electrical conductivity (σ1), and has a thickness of d1. A second region is formed by a second dielectric layer (124), has a second permittivity (ε2) and a second electrical conductivity (σ2), and has a thickness of d2.

The temperature control means (140) may be disposed above, below, or around the first dielectric layer (122) to control the temperature of the first dielectric layer (122) and/or the second dielectric layer (124). For example, when the second dielectric layer (124) is air or a vacuum layer, the electrical conductivity of the second dielectric layer (124) may be substantially constant depending on the temperature. On the other hand, when the first dielectric layer (122) is a high-k dielectric material such as alumina, the electrical conductivity of the first dielectric layer (122) may depend on the temperature. The temperature control means (140) may include at least one of a resistive heater, a hot air source, and an infrared generator.

At a first temperature (T1), the electrical conductivity ratio (σ2/σ2) may be 0.01, and the dielectric constant ratio (ε2/ε1) may be 0.1. At a second temperature (T2) lower than the first temperature, the dielectric constant ratio (ε2/ε1) may be 0.1, and the electrical conductivity ratio (σ2/σ2) may be 0.1.

For example, since the electric conductivity ratio (σ2/σ2) is 0.01 at the first temperature (T1), when the thickness (d1) of the first dielectric is 9 μm and the thickness (d2) of the second dielectric is 1 μm, the intensity of the electric field (E2) of the second region can be about 2 MV/m, and the interfacial surface charge density can be 0.5 [Vε2]. Meanwhile, the intensity of the electric field (E2) of the second region can be about 0.8 MV/m, and the interfacial surface charge density (ρ _si ) can be 0 [Vε2]. Accordingly, when the temperature of the first dielectric layer (122) is modulated over time, a strong second electric field is obtained at a high temperature, and the interfacial surface charge density (ρ _si ) can be set to zero at a low temperature at a desired time.

Alternatively, the temperature control means (140) can change the operating characteristics by changing the temperature of the first dielectric layer (122) and/or the second dielectric layer (124).

Referring to FIGS. 20 to 22, an electrostatic device (10d) according to one embodiment of the present invention includes an electrostatic electrode layer (110); a first dielectric layer (122) disposed on the electrostatic electrode layer; and a temperature control unit (140) for controlling a temperature of the first dielectric layer. The device includes an air gap (124) formed in the first dielectric layer, the air gap being filled with a gas, the first dielectric layer (122) having a first permittivity (ε1) and a first electrical conductivity (σ1), and the gas having a second permittivity (ε2) and a second electrical conductivity (σ2).

The temperature control unit (140) heats the first dielectric layer (122) while an external voltage is applied to the electrostatic electrode layer, and the temperature control unit (140) cools the first dielectric layer (122) while an external voltage is applied to the electrostatic electrode layer. The first dielectric layer (122) has different electrical conductivity depending on the temperature.

The ratio of the second permittivity to the first permittivity (ε2/ε1) is equal to the ratio of the second electrical conductivity to the first electrical conductivity (σ2/σ1).

In a cooled state, the first dielectric layer has a first permittivity and a first electrical conductivity, the second dielectric layer has a second permittivity and a second electrical conductivity, and a ratio of the second permittivity to the first permittivity is equal to a ratio of the second electrical conductivity to the first electrical conductivity. Accordingly, in a cooled state, interface charges are removed. That is, while processing the substrate, the first dielectric layer is maintained at a high temperature to increase electrical conductivity and thereby maintain a high electrostatic force. The processing of the substrate may be substrate transfer, plasma etching, a deposition process, etc. Meanwhile, when the processing of the substrate is completed, the first dielectric layer is set to a low temperature to reduce electrical conductivity and thereby reduce interface charges. Accordingly, when an external power source is removed, immediate detachment is possible.

The present invention can also be applied to other dielectrics other than air gaps.

[Interfacial surface charge density according to opposing voltage pulse]

Figure 23 is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.

Referring to Fig. 23, in the case of Case II, a first voltage is applied to operate the electrostatic device. The electric field (E2) of the second region changes to be saturated over time. If the electric field (E2) of the second region is saturated, the interface can be charged with a negative interfacial surface charge density. The negative interfacial surface charge density can have a relatively large relaxation time (τ).

If it is desired to remove the negative interfacial surface charge density, a second voltage of opposite polarity to the first voltage can be applied. When a second voltage of opposite polarity to the first voltage is applied, the time for the interfacial charge to become zero is given as follows.

[Mathematical formula 9]

When the magnitude of the second voltage is the same as that of the first voltage, the time (t1) at which the interface surface charge density becomes zero can be 0.69 τ.

When the magnitude of the second voltage is twice that of the first voltage, the time (t1) at which the interfacial surface charge density becomes zero can be 0.40 τ. When the magnitude of the second voltage is three times that of the first voltage, the time (t1) at which the interfacial surface charge density becomes zero can be 0.287 τ.

However, the application time of the opposing voltage to remove the interfacial surface charge density can be relatively long due to the large relaxation time (τ).

The above applies equally to Case I and Johnson-Rahbeck type.

Referring to FIG. 1 and FIG. 23, an electrostatic device (10) includes an electrostatic electrode layer (110); and a dielectric layer (122) disposed on the electrostatic electrode layer and having a gap space (124); and a power source (130) for applying a voltage to the electrostatic electrode layer. A dechucking method of this electrostatic device includes a step of the power source (130) applying a first voltage (V0) to adsorb a substrate (120) and accumulate a first interfacial charge between the dielectric layer and the gap space; and a step of the power source (130) applying a second voltage (V1 to V3) having an opposite polarity to the first voltage to erase the first interfacial charge between the gap space and the dielectric layer, thereby performing dechucking.

The relaxation time defined by the resistance and capacitance of the dielectric layer and the gap space is longer than the application time (t1, t2, t3) of the second voltage (V1 to V3).

The absolute value of the second voltage may be greater than the absolute value of the first voltage.

For example, the absolute value of the second voltage may be equal to the absolute value of the first voltage, and the application time of the second voltage may be 0.69 times the characteristic relaxation time defined by the resistance and capacitance of the gap space.

For example, the absolute value of the second voltage may be twice the absolute value of the first voltage, and the application time of the second voltage may be 0.40 times the characteristic relaxation time defined by the resistance and capacitance of the gap space.

For example, the absolute value of the second voltage may be three times the absolute value of the first voltage, and the application time of the second voltage may be 0.287 times the characteristic relaxation time defined by the resistance and capacitance of the gap space.

Referring to FIG. 1 and FIG. 14b, an electrostatic device (10) includes an electrostatic electrode layer (110); and a dielectric layer (122) disposed on the electrostatic electrode layer and having a gap space (124); and a power source (130) for applying a voltage to the electrostatic electrode layer. A dechucking method of the electrostatic device includes a step of applying a first voltage to the power source to adsorb a substrate and accumulate a first interfacial charge between the dielectric layer and the gap space; and a dechucking step of applying a second voltage, which is greater than the first voltage, to induce a discharge in the gap space to reduce the first interfacial charge.

The ratio of the electrical conductivity of the gap space to the electrical conductivity of the dielectric layer (σ2/σ1) may be greater than the ratio of the permittivity of the gap space to the permittivity of the dielectric layer (ε2/ε1).

[Interfacial charge according to bipolar voltage]

Figure 24 is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.

Referring to Fig. 24, in the case of Case II, a first voltage is applied to operate the electrostatic device. The electric field (E2) of the second region changes to saturate over time. The negative interfacial surface charge density can have a relatively large relaxation time (τ).

After the relaxation time (τ) is divided into multiple sections, the positive first voltage and the negative second voltage can be applied alternately. Accordingly, the interface surface charge density can be maintained at a value of almost zero without accumulating over time. Preferably, the relaxation time (τ) can be divided into 10 or more sections.

Accordingly, when the external voltage is removed at the time when the electrostatic force is to be removed, the electrostatic force can be removed immediately as the interface surface charge density becomes almost zero.

Even in the case of Cases I, III, and IV, after dividing the relaxation time (τ) into multiple sections, the positive first voltage and the negative second voltage can be applied alternately. Accordingly, the interface surface charge density can be maintained at a value of almost zero without accumulating over time.

Referring to FIG. 1 and FIG. 24, an electrostatic device (10) according to one embodiment of the present invention includes an electrostatic electrode layer (110); first and second dielectric layers (122, 124) arranged on the electrostatic electrode layer; and a power source (130) that applies voltage to the electrostatic electrode layer.

The operating method of the electrostatic device includes the steps of applying a first voltage to the power source (130) to adsorb the substrate (120) on the dielectric layer and accumulate a first interface charge; and the step of applying a second voltage of opposite polarity to the first voltage to erase the first interface charge accumulated between the first dielectric layer and the second dielectric layer into a charge of opposite polarity.

The first voltage and the second voltage are alternately repeated, and the application time of the first voltage may be shorter than the time constant of the first interface charge.

The application time of the first voltage is the same as the application time of the second voltage, and the time constant of the first interface charge can be 10 seconds or more. For example, it can be effective in the Coulomb type.

The first voltage may have a positive value, the substrate (120) may be charged with a negative charge at the first voltage, and the first interface charge may have a negative value.

Referring to FIG. 1 and FIG. 24, an electrostatic device (10) according to one embodiment of the present invention includes: an electrostatic electrode layer (110); and first and second dielectric layers (122, 124) disposed on the electrostatic electrode layer; and a power source (130) for applying a voltage to the electrostatic electrode layer. An operating method of the electrostatic device includes: a step of applying a first voltage to the power source (130) to adsorb a substrate (120) and accumulate a first interface charge between the first dielectric layer (122) and the second dielectric layer (124); and a step of applying a second voltage having an opposite polarity to the first voltage to accumulate an interface charge having an opposite polarity to the first interface charge, thereby adsorbing the substrate (120).

The application time of the first voltage is shorter than the time constant of the first interface charge. The application time of the first voltage is the same as the application time of the second voltage, and the time constant of the first interface charge may be 10 seconds or more. The first voltage and the second voltage may be alternately repeated.

[Interfacial charge according to UV/visible light irradiation]

FIG. 25a is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.

Figure 25b is a conceptual diagram explaining the operation of the electrostatic device of Figure 25a.

Figure 25c is a conceptual diagram explaining the operation of the electrostatic device of Figure 25a.

Figure 25d is a conceptual diagram explaining the operation of the electrostatic device of Figure 25a.

Figure 26 is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.

Referring to FIGS. 25A to 25D and FIG. 26, a first dielectric layer (122) and a second dielectric layer (124) are laminated between a first electrode (110) and a second electrode (120). A first region is formed by the first dielectric layer (122), has a first permittivity (ε1) and a first electrical conductivity (σ1), and has a thickness of d1. A second region is formed by the second dielectric layer (124), has a second permittivity (ε2) and a second electrical conductivity (σ2), and has a thickness of d2. The electrostatic device may include a light providing unit (150) that controls an interface surface charge density.

The light providing unit (150) can provide ultraviolet/visible light to the interface between the first dielectric layer and the second dielectric layer. The ultraviolet/visible light can generate electrons and holes in the first dielectric layer or the second dielectric layer to control the interface surface charge density. The wavelength of the light irradiation means can be larger than or similar to the band gap energy of the dielectric. Alternatively, the wavelength of the light irradiation means can be in the ultraviolet range.

The light providing unit (150) may include an optical fiber (151) and an ultraviolet light source (152). The optical fiber may be made of a quartz material capable of transmitting ultraviolet light. The optical fiber (150) may be arranged to penetrate the first electrode and the dielectric layer and be exposed to the second dielectric layer. Preferably, the second dielectric layer may be an air gap. The surface of the dielectric layer providing the lower surface of the gap space may be roughened for diffusion.

Referring to Fig. 25b, a first voltage is applied between the first electrode and the second electrode. In this case (Johnson-Rahbek type), the second dielectric layer may be an air gap. The interface charge has a positive value and changes to a saturation state with a relaxation time. Before the saturation state (or steady state), an optical pulse may be irradiated to the first dielectric layer (122) and the second dielectric layer (124). In this case, the second dielectric layer (124) may be an air gap. The optical pulse generates electron-hole pairs to reduce the relaxation time, thereby quickly reaching the saturation state.

When a positive voltage is applied to the first electrode (110) and the second electrode is grounded, the first electrode may be charged with a positive charge and the second electrode may be charged with a negative charge. The interface charge may have a positive value. When external light is irradiated, electron-hole pairs generated in the first dielectric layer may be formed. The electrons may move in the direction of the first electrode, and the holes may move in the direction of the interface. Accordingly, the interface charge density may reach a saturation state in a short time. It is assumed that the physical properties of the air gap are not changed by light irradiation.

Next, the first voltage is removed between the first electrode and the second electrode. In this case, the interface charge can be erased with a relaxation time. The first electrode can be grounded and the second electrode can be grounded. Accordingly, since the interface charge has a positive value, the first electrode can be charged with a negative charge and the second electrode can be charged with a negative charge. The first electric field (E1') of the first region can be in the direction of the first electrode, and the second electric field (E2') of the second region can be in the direction of the second electrode. When the light pulse is irradiated, the first dielectric layer can generate electron-hole pairs. The electrons can move toward the interface, and the holes can move toward the first electrode. Accordingly, the interface charge can be erased at a faster rate.

Meanwhile, when the electrical conductivity of each dielectric changes due to light irradiation, a new equilibrium state (steady state) can be reached.

Referring to Fig. 25c, a first voltage is applied between the first electrode and the second electrode. In this case (Johnson-Rahbek type), the second dielectric layer may be an air gap. The interface charge has a positive value and changes to a saturation state with a relaxation time. An optical pulse may be irradiated to the dielectric before the saturation state. In this case, the optical pulse may generate charge-holes to reduce the relaxation time.

Next, a second voltage having an opposite polarity to the first voltage is applied between the first electrode and the second electrode. The first electrode may be charged with a negative charge, and the second electrode may be charged with a positive charge. The interface charge has a positive value. When light is irradiated, electron-hole pairs may be generated in the first dielectric layer. The electrons may move toward the interface, and the holes may move toward the first electrode. In this case, the interface charge may be charged with an opposite polarity charge with a relaxation time. When a light pulse is irradiated, the interface charge may be charged with an opposite polarity charge at a faster rate. That is, when a second voltage having an opposite polarity is applied for dechucking and light is irradiated, the interface charge reaches a zero state faster. When the interface charge is zero and the light and/or the second voltage are removed, the interface charge is removed.

Referring to Fig. 25d, a first voltage is applied between the first electrode and the second electrode. In this case (Coulomb type), the second dielectric layer may be an air gap. The interface charge has a negative value and changes to a saturation state with a relaxation time. Before the saturation state, a light pulse may be irradiated to the first dielectric. In this case, the light pulse may generate charge-holes to erase the interface charge.

Then, the first voltage can be removed between the first electrode and the second electrode. In this case, the interface charge can be extinguished with a relaxation time. When a light pulse is irradiated, the interface charge can be extinguished at a faster rate. That is, for dechucking, when light is irradiated, the interface charge can reach a zero state faster.

Referring to FIG. 26, the electrostatic device (10e, 10f) includes an electrostatic electrode layer (110); a dielectric layer (122, 124) disposed on the electrostatic electrode layer; and a light providing unit (150) that provides visible light/ultraviolet light to the dielectric layer. The light providing unit (150) may include an optical fiber (151) and a light source (152).

At least one optical fiber (151) includes at least one optical fiber disposed in an air gap (124) through the electrostatic electrode layer (110) and the dielectric layer (122). The optical fiber can transmit ultraviolet light. The core and cladding of the optical fiber (151) can be made of quartz material. The surface of the dielectric layer providing the lower surface of the air gap (124) can be roughened for diffusion. The light providing unit (150) can generate electron-holes in the dielectric layer to eliminate interface charges.

Referring to FIGS. 25 and 26, the electrostatic device (10e, 10f) includes: an electrostatic electrode layer (110); a dielectric layer (122, 124) disposed on the electrostatic electrode layer; and a light providing unit (150) providing ultraviolet light to the dielectric layer (122, 124). The dechucking method of the electrostatic device includes: a step of applying a first voltage to the electrostatic electrode layer (110); a step of removing the first voltage applied to the electrostatic electrode layer (110); a step of providing light to the dielectric layer (122, 124) through the light providing unit (150); and a step of erasing charges accumulated on the back surface of the dielectric layer (122, 124) or the substrate (120) disposed on the dielectric layer by the light.

The removal of the first voltage applied to the electrostatic electrode layer and the provision of the light can be performed simultaneously. The light can be provided after the first voltage applied to the electrostatic electrode layer is removed. After the first voltage applied to the electrostatic electrode layer is removed, the counter pulse of the opposite polarity and the provision of the light can be provided sequentially or simultaneously.

[Electric field in plasma situation]

In a plasma-generated situation, the electrostatic device can be operated. Specifically, the second electrode is a semiconductor substrate to be processed, and plasma can be generated on the semiconductor substrate. The plasma can be considered as electrically grounded. The electrostatic device can be a substrate adsorption device of a plasma substrate processing device that processes a substrate with plasma.

[For multilayer structures or dielectric deposition on the back of the substrate]

The operating principle of a three-layer electrostatic device according to one embodiment of the present invention is described.

Figure 27 is a conceptual diagram explaining the structure of an electrostatic device according to one embodiment of the present invention.

Referring to FIG. 27, a first dielectric layer (122), a second dielectric layer (124), and a third dielectric layer (126) are laminated between a first electrode (110) and a second electrode (120). A first region is formed by a first dielectric layer (122), has a first permittivity (ε1) and a first electrical conductivity (σ1), and has a thickness of d1. A second region is formed by a second dielectric layer (124), has a second permittivity (ε2) and a second electrical conductivity (σ2), and has a thickness of d2. A third region is formed by a third dielectric layer (126), has a third permittivity (ε3) and a third electrical conductivity (σ3), and has a thickness of d3. A total thickness is d. The third dielectric layer (126) may be a material coated on the second electrode (120). V0 is applied between the first electrode (110) and the second electrode (120).

The interfacial surface charge density between the first dielectric layer and the second dielectric layer is ρ _sa . The interfacial surface charge density between the second dielectric layer and the third dielectric layer is ρ _sb . The electric field of the first dielectric layer is E1 , the electric field of the second dielectric layer is E2 , and the electric field of the third dielectric layer is E3 .

The electric fields in the first region (E1), the second region (E2), and the third region (E3) are given as follows when the interface charge is ignored.

[Mathematical Formula 10]

The electric fields (E1, E2, E3) may depend only on the permittivity in each region in the initial state. The electric field (E3) of the third region may be the same as in the case where the third dielectric layer (126) is absent, when the thickness of the third dielectric layer (126) is relatively very thin.

The electric field in the first region (E1), the electric field in the second region (E2), and the electric field in the third region (E3) are given as follows in the steady state when considering the electrical conductivity.

[Mathematical Formula 11]

The electric fields (E1, E2, E3) may depend only on the electrical conductivity in each region in the normal state, without depending on the permittivity. The electric field (E3) of the third region may be the same as in the case where the third dielectric layer (126) is absent, when the thickness of the third dielectric layer (126) is relatively very thin.

The surface charge density (ρ _sa , ρ _sb ) of the interface is given as follows in steady state.

[Mathematical formula 12]

At adjacent interfaces, if the ratio of electrical conductivities is equal to the ratio of permittivities, the interfacial charge density becomes zero.

In the third region, the electrostatic pressure (f) of the second electrode is given as follows.

[Mathematical formula 13]

The electric field in the first region (E1), the electric field in the second region (E2), and the electric field in the third region (E3) are given as follows in the transient state.

[Mathematical formula 14]

The surface charge density (ρsa, ρsb) of the interface is given as follows in the transient state.

[Mathematical Formula 15]

The eigenvalue (λ) of the equation is given as follows.

[Mathematical Formula 16]

Here, the relaxation time (τ1, τ2) is the reciprocal of the absolute value of the eigenvalues.

The eigenvector can be given as follows:

[Mathematical formula 17]

The interfacial surface charge density (ρ _sa , ρ _sb ) of the interface is given as follows.

[Mathematical expression 18]

By applying the initial conditions to the above equation, we can obtain coefficients C1 and C2.

Accordingly, the electric field (E1, E2, E3) over time can be given by mathematical expression 14.

[Multilayer feature comparison]

Case V d1=90 [um] d2=10 [um] d3=0.1 [um] ε1=10 [ε ₀ ] ε2=1 [ε ₀ ] ε3=4 [ε ₀ ] σ1=100 [10^(-12) /Ωm] σ2=1 [10^(-12) /Ωm] σ3=0.01 [10^(-12) /Ωm]

Case VI d1=90 [um] d2=10 [um] d3=0.1 [um] ε1=10 [ε ₀ ] ε2=1 [ε ₀ ] ε3=4 [ε ₀ ] σ1=10^(-4) [10^(-12) /Ωm] σ2=1 [10^(-12) /Ωm] σ3=10^(-4) [10^(-12) /Ωm]

Case VII d1=90 [um] d2=10 [um] d3=0.1 [um] ε1=10 [ε ₀ ] ε2=1 [ε ₀ ] ε3=4 [ε ₀ ] σ1=10 [10^(-12) /Ωm] σ2=1 [10^(-12) /Ωm] σ3=10^(-4) [10^(-12) /Ωm]

Normal condition Case V Case VI Case VII E3 4.78 [V MV/m] 0.01 [V MV/m] 10 [V MV/m] ρ _sa 0.043 [V 10^(-5)C/m^2] -0.1 [V 10^(-5)C/m^2] 0 [V 10^(-5)C/m^2] ρ _sb 19 [V 10^(-5)C/m^2] 0. 033 [V 10^(-5)C/m^2] 40 [V 10^(-5)C/m^2] τ1 10 [sec] 21 [sec] 16 [sec] τ2 668 [sec] 131,700 [sec] 66,600 [sec]

When the third dielectric layer (126) is present, the thickness (d3) of the third dielectric layer is very thin at 0.1 um, but the relaxation time (τ) increases significantly. Here, the second permittivity of the second dielectric layer (124) is the permittivity of vacuum (ε0), and the second resistivity of the second dielectric layer (124) was 10^12 Ωm.

In Case V, the first interface surface charge density (ρ _sa ) is at the level of 0.043 in the steady state, and the second interface surface charge density (ρ _sb ) is at the level of 19. Therefore, the relaxation time (τ = τ1 + τ2) in the steady state has a large value of 678 seconds.

In Case VI, the first interface surface charge density (ρ _sa ) is at the level of -0.1 in the steady state, and the second interface surface charge density (ρ _sb ) is at the level of 0.033. Therefore, the relaxation time (τ = τ1 + τ2) in the steady state has a very large value of approximately 131,700 seconds.

In Case VII, the first interface surface charge density (ρ _sa ) is at the level of 0 in the steady state, and the second interface surface charge density (ρ _sb ) is at the level of 40. Therefore, the relaxation time (τ = τ1 + τ2) in the steady state has a very large value of approximately 66,600 seconds.

Case V has a relaxation time of 678 seconds and has a high interfacial charge in the steady state. Due to the relaxation time of 678 seconds, if the adsorption time (several seconds to several tens of seconds) is shorter than the relaxation time (678 seconds), the steady state may not be reached. Depending on the adsorption time, the adsorption force may change, resulting in unstable operation. In addition, during dechucking, the removal of the interfacial charge may not be easy due to the large relaxation time.

In the case of having a third dielectric layer (126) with high resistivity, Case VI can maintain the initial value of the electrostatic force during the adsorption time (typically several seconds to several hundred seconds) due to the very long relaxation time (131,700 seconds). Accordingly, stable operation can be performed.

In the case of Case VI, the interface charge density is relatively low in the steady state. The initial value of the third electric field (E3) is 0.013, and the third electric field (E3) is 0.01 in the steady state. The change is small, about 20%. Therefore, due to the large relaxation time (131,700 seconds), the third electric field (E3) in the initial state can be maintained for the adsorption time (typically several seconds to several hundred seconds).

Case VII has the largest third electric field. If the adsorption time (several seconds to several hundred seconds) is small compared to the relaxation time (about 66,600 seconds), the initial third electric field (E3) can be used. Due to the large relaxation time, the initial third electric field (E3) can be maintained for the adsorption time (typically several seconds to several hundred seconds).

In the case of the Johnson-Rahbek type (Case V), when the third dielectric layer (126) is provided, another means of accumulating interfacial surface charges, such as ultraviolet light, may be required to increase the electrostatic force by accumulating the interfacial surface charge density faster than the relaxation time when an external voltage is applied.

In the case of the Johnson-Rahbek type (Case V), when the third dielectric layer (126) is provided, other means of removing the interfacial surface charge, such as ultraviolet light, may be required to remove the interfacial surface charge density faster than the relaxation time when the external voltage is removed.

When the ratio of electrical conductivities in neighboring dielectrics is equal to the ratio of permittivity, the interfacial surface charge density becomes zero. Therefore, stable adsorption and desorption operations are possible regardless of the relaxation time.

For example, if the material (third dielectric layer) deposited on the back surface of the substrate is a silicon oxide film, the second dielectric layer (124) may be a material having the same characteristics as the silicon oxide film. The first dielectric layer (122) may be a high-dielectric constant aluminum oxide film. If the ratio of the electric conductivities of the second dielectric layer to the first dielectric layer (σ2/σ1) is equal to the ratio of the permittivities (ε2/ε1), the interfacial charge density becomes zero. Therefore, even in a multilayer structure, elimination of interfacial charges is possible.

Since the electrical conductivity of the dielectric depends on temperature, controlling the interfacial charge is possible by changing the temperature.

According to a modified embodiment of the present invention, when the second dielectric layer is an air gap (or vacuum gap), and an air gap cavity is formed between the first dielectric layer and the thin third dielectric layer, the relaxation time is greatly increased due to the characteristics of the third dielectric layer (high third resistivity), and the third electric field can be relatively increased.

Referring to FIG. 27, an electrostatic device (10g) according to one embodiment of the present invention includes: an electrostatic electrode layer (110); a first dielectric layer (122) disposed on the electrostatic electrode layer (110); a second dielectric layer (124) disposed on the first dielectric layer; a substrate (120) disposed on the second dielectric layer; and a third dielectric layer (126) disposed between a lower surface of the substrate and the second dielectric layer.

The first dielectric layer (122) has a first permittivity (ε1) and a first electrical conductivity (σ1), the second dielectric layer (124) has a second permittivity (ε2) and a second electrical conductivity (σ2), and the third dielectric layer (126) has a third permittivity (ε3) and a third electrical conductivity (σ3).

The ratio of the second dielectric constant to the first dielectric constant (ε2/ε1) is equal to the ratio of the second electrical conductivity to the first electrical conductivity (σ2/σ1). Accordingly, the interfacial charge between the first dielectric layer (122) and the second dielectric layer (124) is zero.

The ratio of the third dielectric constant to the second dielectric constant (ε3/ε2) is equal to the ratio of the third electrical conductivity to the second electrical conductivity (σ3/σ2). Accordingly, the interfacial charge between the second dielectric layer (124) and the third dielectric layer (126) is zero.

[Multilayer structure of series and parallel connections]

Figure 28 is a conceptual diagram explaining the structure of an electrostatic device according to one embodiment of the present invention.

Referring to FIG. 28, in the electrostatic device (10h), a first dielectric layer (122), a second dielectric layer (124), and a third dielectric (126) are laminated between a first electrode (110) and a second electrode (120). A first region is formed of a first dielectric layer (122), has a first permittivity (ε1) and a first electrical conductivity (σ1), and has a thickness of d1. A second region is formed of a second dielectric layer (124), has a second permittivity (ε2) and a second electrical conductivity (σ2), and has a thickness of d2. A third region is formed of a third dielectric (126), has a third permittivity (ε3) and a third electrical conductivity (σ3), and has a thickness of d3. A total thickness is d. The third dielectric (126) may be a material coated on the second electrode (120).

For example, the second dielectric layer (124) can be divided into three sections.

The first section can have a second main permittivity (ε2) and a second main electrical conductivity (σ2). The second section can have a second reserve permittivity (ε'2) and a second reserve electrical conductivity (σ'2). The third section can have the same physical properties as the first dielectric.

The section-wise characteristics of the second dielectric affect the electric field of the third dielectric connected in series thereon. Accordingly, the characteristics of the third electric field of the third dielectric can be changed section-wise.

For example, when only the first and third sections are used, the first section may be an air gap. In this case, the electric field (E3) of the third dielectric corresponding to the first section may increase relatively compared to the electric field of the third dielectric corresponding to the third section.

When the third dielectric layer is deposited on the back surface of the substrate, the electrostatic device needs to maintain a high electrostatic force at the edge of the substrate to prevent leakage of the cooling gas flowing in the air gap. In this case, the second section can have a second preliminary permittivity (ε'2) and a second preliminary electrical conductivity (σ'2). When the second section is formed in a ring shape to have a low permittivity or a high electrical conductivity, a high electrostatic force can be provided to a position corresponding to the second section.

[Bipolar electrostatic device]

A bipolar electrostatic device can be operated by applying a voltage between two electrostatic electrodes. It is preferable that the adsorbate has conductivity. The operating principle of a unipolar electrostatic device can be applied to a bipolar electrostatic device in the same manner. In the case of a bipolar device with the same area and symmetry, the electrostatic force can be 1/4 of that of a unipolar device for the same voltage difference.

Figure 29 is a conceptual diagram illustrating an electrostatic device according to one embodiment of the present invention.

Referring to Fig. 29, a first dielectric layer (122) and a second dielectric layer (124) are laminated between a first electrode (110) and a second electrode (120). The first region is formed by the first dielectric layer (122), has a first dielectric constant (ε1) and a first electrical conductivity (σ1), and has a thickness of d1.

The second region is formed by a second dielectric layer (124), has a second permittivity (ε2) and a second electrical conductivity (σ2), and has a thickness of d2. The second dielectric layer may include a second spare dielectric layer (124'). The second spare dielectric layer has a second permittivity (ε'2) and a second electrical conductivity (σ'2), and has a thickness of d2. The second dielectric layer (124) and the second spare dielectric layer (124') are arranged in parallel. For example, the second dielectric layer (124) may be an air gap, and the second spare dielectric layer (124') may be made of the same material as the first dielectric layer (122).

The first electrode (110) may include a first electrostatic electrode (110a) and a second electrostatic electrode (110b) that are arranged adjacently to form a pair as electrostatic electrode layers connected to an external power source. The first electrostatic electrode (110a) and the second electrostatic electrode (110b) may have the same area.

A first conductive layer (129a) may be placed between a first dielectric layer (122) and a second dielectric layer (124) on a first electrostatic electrode (110a). The first conductive layer (129a) may be charged with a positive charge.

A second conductive layer (129b) may be placed between the first dielectric layer (122) and the second dielectric layer (124) on the second electrostatic electrode (129b). The second conductive layer (129b) may be charged with a negative charge.

The charge (+Q) charged to the first conductive layer (129a) and the charge (-Q) charged to the second conductive layer (129b) have different signs and may have the same value. Accordingly, when the first conductive layer (129a) and the second conductive layer (129a) are electrically connected to each other, the charge accumulated in the first conductive layer (129a) can be eliminated, and the charge accumulated in the second conductive layer (129b) can be eliminated.

A resistive layer (127) may be arranged to connect the first conductive layer and the second conductive layer to each other. The resistive layer (127) may be made of the same material as the first conductive layer and the second conductive layer, or the resistive layer (127) may be a material whose electrical conductivity changes when light is provided from the outside. For example, the resistive layer (127) may be CdS.

In the case of the Coulomb type, when an interface charge is generated, the electrostatic force decreases. When the first conductive layer and the second conductive layer are directly connected, the interface charges cancel each other out, so that the electrostatic force can be maintained in the initial state.

Meanwhile, in the case of the Johnson-Rahbek type, high electrostatic force is generated by accumulating interfacial charges. After accumulating interfacial charges and performing adsorption operation, the resistance of the resistive layer can be reduced by light in the charge erasure step (dechucking step). Accordingly, when the resistive layer (127) receives light from the outside, the electrical conductivity changes, and the interfacial charges can move to each other without being connected to an external circuit and reach an erasure state.

Referring to FIG. 29, an electrostatic device (10i) according to one embodiment of the present invention includes an electrostatic electrode layer (110a, 110b); a first dielectric layer (122) disposed on the electrostatic electrode layer; a resistance layer (129a, 129b, 127) disposed on the first dielectric layer; and an air layer (124) disposed on the resistance layer (129a, 129b, 127). A protrusion (124') formed on the first dielectric layer (122) forms an air layer between the absorbent (120) and the first dielectric layer (122), and the electrical conductivity of the resistance layer (127) increases due to light. The resistance layer (129a, 129b, 127) may be CdS.

The resistive layers (129a, 129b) act as layers that accumulate interface charges, and when light is irradiated to remove the interface charges, the resistive layers (129a, 129b) act as conductors so that the charges can be removed.

Referring to FIG. 29, an electrostatic device (10i) according to one embodiment of the present invention includes: a first electrostatic electrode (110a) provided with a first voltage; a second electrostatic electrode (110b) provided with a second voltage; a first dielectric layer (122) disposed on the first electrostatic electrode (110a) and the second electrostatic electrode (110b); a first conductive layer (129a) disposed on the first dielectric layer at a position corresponding to the first electrostatic electrode (110a); a second conductive layer (129b) disposed on the first dielectric layer at a position corresponding to the second electrostatic electrode (110b); and a photoresist layer (127) connecting the first conductive layer (129a) and the second conductive layer (129b).

The photoresist layer (127) includes an air layer (124) disposed on the first conductive layer (129a) and the second conductive layer (129b), and the protrusion (124') formed on the first dielectric layer forms an air layer between the adsorbate and the first dielectric layer, and the electrical conductivity of the photoresist layer (127) increases due to light. That is, in the adsorption state, light is not irradiated to the photoresist layer (127), but in the state where the first voltage and the second voltage are removed for desorption, light is irradiated to the photoresist layer (127) to eliminate interface charges. The photoresist layer (127) may be CdS.

Figure 30 is a conceptual diagram illustrating an electrostatic device of a typical substrate processing device.

Referring to FIG. 30, in the electrostatic device (20), a first dielectric layer (122) and a second dielectric layer (124) are arranged between a first electrode (110) and a second electrode (120). The second dielectric layer (124) is an air gap. In addition, the first dielectric layer (122) protrudes from an edge of the first dielectric layer (122). This protruding portion (128) prevents gas supplied through a gas line (170) from leaking out. The second electrode (120) may be a semiconductor substrate.

However, the electric field strength at the protruding portion corresponds to point A and is relatively small as a value obtained by dividing the applied voltage by the gap (d). Therefore, the electric field at the protruding portion (point A) is lower than the electric field in the gap space (point B), and the suction force is small due to the low electric field. Therefore, gas can leak out through the protruding portion.

Even if roughening is performed on the protruding portion (128), the roughening can locally increase the electric field and electrostatic force by reducing the thickness of the gap space. However, it cannot provide a stable electrostatic force in all areas. In addition, the roughening can provide a passage through which a cooling gas such as helium can leak out. On the other hand, if the roughening treatment area is increased to suppress gas leakage, the cooling performance of the gas decreases. In addition, the roughening treatment is vulnerable to contamination. In addition, the roughening treatment has difficulty in providing stable characteristics due to wear.

Although the Coulomb type was explained above, a similar problem occurs in the Johnson-Rahbek type.

Figures 31 to 33 are conceptual diagrams illustrating an electrostatic device according to one embodiment of the present invention.

Referring to FIG. 31, the electrostatic device (300) includes an electrostatic electrode layer (110); a dielectric layer (122) disposed on the electrostatic electrode layer (100); and a ring-shaped protrusion (128) disposed at an edge of the dielectric layer (122). The protrusion (128) forms a recessed portion, and the recessed portion is filled with a cooling gas. The protrusion (128) includes a flat region (101a) and a roughened surface treatment region (101b).

The above dielectric layer (122) includes an embossing area on the inside of the protrusion (128), and the embossing area can maintain a constant distance from the second electrode or the substrate.

The electric field strength of the flat area (101a) corresponds to point A, the electric field of the surface treatment area corresponds to point C, and the electric field of the sunken area corresponds to point B.

The roughened surface treatment area (101b) provides a high electric field (electrostatic power), and the flat area (101a) performs a gas sealing function to prevent gas leakage.

The above flat area (101a) can be arranged on the outside and the surface treatment area (101b) can be arranged on the inside. Accordingly, it is possible to suppress contaminants from being deposited on the surface treatment area.

The width of the above surface treatment area may be greater than the width of the above flat area. Accordingly, the electrostatic force increases.

The roughness of the above surface treatment area can be 0.1 um to 1 um. In the roughness treatment, the ratio (d2'/d) of the maximum height of the roughness (d2') to the total thickness (d) can be 0.001 to 0.01.

When the dielectric constant ratio (ε2/ε1) is 0.1 and the total thickness (d) of the dielectric layer is 100 μm, the change in the gap (d2') due to roughness is not large. Therefore, fine roughening treatment can be easily affected by contamination.

When the total thickness (d) of the dielectric layer is 100 μm, the height (d2) of the protrusion can be 5 μm to 20 μm. The height (d2) of the protrusion can depend on the pressure of the cooling gas and the type of the gas. When the height (d2) of the protrusion increases, the intensity of the electric field decreases, thereby decreasing the electrostatic force. The ratio of the height (d2) of the protrusion to the total thickness (d) of the dielectric layer can be 0.2 or less.

In the case of the Coulomb type, when the electric conductivity ratio is taken into account (for example, when the electric conductivity ratio is 10)), if the ratio (d2'/d) of the maximum height (d2') of the roughness is too small, the relaxation time may decrease. A small relaxation time may decrease the intensity of the electric field over time. Therefore, the ratio (d2'/d) of the maximum height (d2') of the roughness may be 0.001 to 0.01.

The Coulomb type was explained above, but it is applied similarly in the Johnson-Rahbek type.

In the Johnson-Rahbek type, when the electric conductivity ratio is less than 0.1 (for example, when the electric conductivity ratio is 0.01), as shown in FIG. 5, the intensity of the electric field changes rapidly depending on the air gap (d2'). This characteristic reduces the stability depending on the surface roughness of the adsorbate, and when the surface roughness decreases, the electric field increases, which increases micro-discharge and reduces the stability. Meanwhile, as shown in FIG. 9, when the ratio of the maximum heights (d2'/d) is 0.01 or less, the relaxation time may increase. Therefore, when a fast relaxation time is considered, the ratio of the maximum heights (d2'/d) can be 0.01 or more. Based on d=100 um, d2' can be 1 um or more.

Referring to FIG. 32, the electrostatic device (300a) includes an electrostatic electrode layer (110); a dielectric layer (122) disposed on the electrostatic electrode layer (100); and a ring-shaped protrusion (128) disposed at an edge of the dielectric layer (122). The protrusion (128) forms a recessed portion, and the recessed portion is filled with a cooling gas. The protrusion (128) includes a flat region (101a) and a roughened surface treatment region (101b).

The above flat area (101a) can be placed on the inside and the above surface treatment area (101b) can be placed on the outside.

Referring to FIG. 33, the electrostatic device (300b) includes an electrostatic electrode layer (110); a dielectric layer (122) disposed on the electrostatic electrode layer (100); and a ring-shaped protrusion (128) disposed at an edge of the dielectric layer (122). The protrusion (128) forms a recessed portion, and the recessed portion is filled with a cooling gas. The protrusion (128) includes a flat region (101a) and a roughened surface treatment region (101b).

The above flat region (101a) includes a first flat region and a second flat region, and the surface treatment region (101b) can be arranged between the first flat region and the second flat region. Accordingly, a balance of force can be maintained.

Figures 34 to 36 are conceptual diagrams illustrating an electrostatic device according to one embodiment of the present invention.

Referring to FIG. 34, the electrostatic device (400) includes an electrostatic electrode layer (110); a dielectric layer (122) disposed on the electrostatic electrode layer; and a first ring-shaped protrusion (102a) disposed at an edge of the dielectric layer (122) and a second ring-shaped protrusion (102b) that protrudes further than the first protrusion (102a). The second protrusion or the first protrusion forms a recessed portion, and the recessed portion is filled with a cooling gas.

When the dielectric constant ratio (ε2/ε1) is 0.1, the electric field of the second protrusion (102b) corresponds to point A, the electric field of the first protrusion (102a) corresponds to point C, and the electric field of the sunken area corresponds to point B. Accordingly, the first protrusion can stably provide a high electric field to locally increase the electrostatic force. This step structure is more resistant to contamination and has excellent reproducibility than roughening treatment.

The second protrusion (102b) may be positioned on the outside to surround the first protrusion (102a). The width of the first protrusion (102a) may be larger than the width of the second protrusion (102a).

The height of the first protrusion (102a) may be 1/2 to 19/20 of the height of the second protrusion (102b). For example, if the height of the second protrusion (102b) is 10 um, the gap (d2') may be 5 um to 0.5 um. If the gap (d2') is too small, it may be susceptible to contamination.

When the thickness of the dielectric layer (122) is 100 μm, the height (d2) of the second protrusion may be 5 μm to 20 μm.

The Coulomb type was explained above, but it is applied similarly in the Johnson-Rahbek type.

Referring to FIG. 35, an electrostatic device (400a) includes an electrostatic electrode layer (110); a dielectric layer (122) disposed on the electrostatic electrode layer; and a first ring-shaped protrusion (102a) disposed at an edge of the dielectric layer (122) and a second ring-shaped protrusion (102b) that protrudes further than the first protrusion (102a). The second protrusion or the first protrusion forms a recessed portion, and the recessed portion is filled with a cooling gas.

The first protrusion (102a) can be positioned on the outside to surround the second protrusion (102b).

Referring to FIG. 36, an electrostatic device (400b) includes an electrostatic electrode layer (110); a dielectric layer (122) disposed on the electrostatic electrode layer; and a first ring-shaped protrusion (102a) disposed at an edge of the dielectric layer (122) and a second ring-shaped protrusion (102b) that protrudes further than the first protrusion (102a). The second protrusion or the first protrusion forms a recessed portion, and the recessed portion is filled with a cooling gas.

The second protrusion (102a) may include a second inner protrusion and a second outer protrusion that are spaced apart from each other. The first protrusion (102a) may be positioned between the second inner protrusion and the second outer protrusion.

Figures 37 to 44 are conceptual diagrams illustrating an electrostatic device according to one embodiment of the present invention.

Referring to FIG. 37, the electrostatic device (500) includes an electrostatic electrode layer; a first dielectric layer (22) disposed on the electrostatic electrode layer; and a ring-shaped second dielectric layer (124') disposed at an edge of the first dielectric layer (122). The second dielectric layer (124') forms a sunken portion (124) in the form of an air gap. The sunken portion is filled with a cooling gas.

The cooling gas is connected to the air gap through a conduit (170) penetrating the first dielectric layer (122).

The second dielectric constant (ε2') of the second dielectric layer (124') is smaller than the first dielectric constant (ε1) of the first dielectric layer (122). In addition, the sunken portion has a second main dielectric constant (ε2) as an air gap. The second dielectric constant (ε2') of the second dielectric layer (124') is larger than the second main dielectric constant (ε2) of the air gap.

When the dielectric constant ratio (ε2/ε1) is 0.1, the electric field of the second dielectric layer (124') corresponds to point A. In addition, the electric field of the sunken area corresponds to point B. Accordingly, the electric field of the second dielectric layer (124') relatively increases to provide a strong electrostatic force.

For example, when the first dielectric constant ratio (ε2/ε1) is 0.1, the second dielectric constant (ε2') of the second dielectric layer (124') is set to be smaller than the first dielectric constant (ε1) of the first dielectric layer (122), so that when the second dielectric constant ratio (ε2'/ε1) is changed to a level of 0.4, the intensity of the electric field of the second dielectric layer (124') relatively increases. That is, the first dielectric layer is an aluminum oxide film, the second dielectric layer (124') is a silicon oxide film, and the second main dielectric layer (124) is an air gap. The thickness (d2) of the second dielectric layer (124') can be 0.01 to 0.2 with respect to the total thickness (d) of the dielectric.

Referring to FIG. 38, the electrostatic device (500b) includes an electrostatic electrode layer; a first dielectric layer (22) disposed on the electrostatic electrode layer; and a ring-shaped second dielectric layer (124') disposed at an edge of the first dielectric layer (122). The second dielectric layer (124') forms a sunken portion (124) in the form of an air gap. The sunken portion is filled with a cooling gas.

The cooling gas is connected to the air gap through a conduit (170) penetrating the first dielectric layer (122).

The second dielectric layer (124') has a second electrical conductivity (σ2') and a second permittivity (ε2'). The sunken portion (124) has a second main electrical conductivity (σ2) and a second main permittivity (ε2). The first dielectric layer (122) has a first electrical conductivity (σ1) and a first permittivity (ε1).

The second main electrical conductivity (σ2) is smaller than the first electrical conductivity (σ1). Additionally, the second electrical conductivity (σ2') is smaller than the first electrical conductivity (σ1).

When the electric conductivity ratio (σ2/σ1) is 0.01, the electric field in the second dielectric layer is at point A. When the electric conductivity ratio (σ2'/σ1) is 0.1, the electric field in the sunken area is at point B.

Accordingly, the ring-shaped second dielectric layer (124') can have a higher electric field than the sunken portion (air gap). Accordingly, gas leakage is suppressed.

Referring to FIG. 39, in the electrostatic device (500c), the second dielectric layer (124') includes a flat region (101a) and a roughened surface treatment region (101b). The flat region (101a) may be arranged outside the surface treatment region.

In the case of the Coulomb type, the second permittivity (ε2') of the second dielectric layer (124') is reduced compared to the first permittivity (ε1) of the first dielectric layer (122), and an air gap is formed by roughening treatment, thereby increasing the intensity of the electric field.

In the case of the Johnson-Rahbek type, the second electrical conductivity (σ2') of the second dielectric layer (124) is reduced compared to the first electrical conductivity (σ1) of the first dielectric layer (122), and when an air gap is formed by roughening treatment, the intensity of the electric field increases.

Referring to FIG. 40, in the electrostatic device (500d), the flat area (101a) can be placed outside the surface treatment area.

In the case of the Coulomb type, the second permittivity (ε2') of the second dielectric layer (124') is reduced compared to the first permittivity (ε1) of the first dielectric layer (122), and an air gap is formed by roughening treatment, thereby increasing the intensity of the electric field.

In the case of the Johnson-Rahbek type, the second electrical conductivity (σ2') of the second dielectric layer (124) is reduced compared to the first electrical conductivity (σ1) of the first dielectric layer (122), and when an air gap is formed by roughening treatment, the intensity of the electric field increases.

Referring to FIG. 41, in the electrostatic device (500e), the flat region (101a) may be arranged outside the surface treatment region. The second dielectric layer (124') includes the flat region (101a) and the roughened surface treatment region (101b). The flat region (101a) may be arranged between the surface treatment regions (101b) that are spaced apart from each other.

In the case of the Coulomb type, the second permittivity (ε2') of the second dielectric layer (124') is reduced compared to the first permittivity (ε1) of the first dielectric layer (122), and an air gap is formed by roughening treatment, thereby increasing the intensity of the electric field.

In the case of the Johnson-Rahbek type, the second electrical conductivity (σ2') of the second dielectric layer (124) is reduced compared to the first electrical conductivity (σ1) of the first dielectric layer (122), and when an air gap is formed by roughening treatment, the intensity of the electric field increases.

Referring to FIG. 42, the electrostatic device (500f) includes an electrostatic electrode layer; a first dielectric layer (22) disposed on the electrostatic electrode layer; and a ring-shaped second dielectric layer (124') disposed at an edge of the first dielectric layer (122). The second dielectric layer (124') forms a sunken portion (124) in the form of an air gap. The sunken portion is filled with a cooling gas.

The second dielectric layer (124') may include a first protruding region (102a) and a second protruding region (102b) that protrudes further than the first protruding region. The second protruding region may be arranged on the outer surface of the first protruding region.

In the case of the Coulomb type, the second permittivity (ε2') of the second dielectric layer (124') is reduced compared to the first permittivity (ε1) of the first dielectric layer (122), and an air gap is formed by step processing, thereby increasing the intensity of the electric field.

In the case of the Johnson-Rahbek type, the second electrical conductivity (σ2') of the second dielectric layer (124) is reduced compared to the first electrical conductivity (σ1) of the first dielectric layer (122), and when an air gap is formed by step processing, the intensity of the electric field increases.

Referring to FIG. 43, referring to the electrostatic device (500g), the second dielectric layer (124') may include a first protruding region (102a) and a second protruding region (102b) that protrudes further than the first protruding region. The first protruding region may be arranged on the outer surface of the second protruding region.

Referring to FIG. 44, referring to the electrostatic device (500h), the second dielectric layer (124') may include a first protruding region (102a) and a second protruding region (102b) that protrudes further than the first protruding region. The second protruding regions may be spaced apart from each other, and the first protruding region may be disposed between the second protruding regions.

Figure 45 is a conceptual diagram showing an electrostatic device according to one embodiment of the present invention.

Referring to FIG. 45, the electrostatic device (600) has a first dielectric layer (122) and a second dielectric layer (124) laminated between a first electrode (110) and a second electrode (120). The first dielectric layer (122) has a first permittivity (ε1) and a first electrical conductivity (σ1), and has a thickness of d1. The second dielectric layer (124) has a second permittivity (ε2) and a first electrical conductivity (σ2), and has a thickness of d2. The second spare dielectric layer (124') may be made of the same or different material as the first dielectric layer (122). The second dielectric layer (124) may be an air gap or a vacuum gap.

A conductive layer (129) may be placed between the first dielectric layer (122) and the second dielectric layer (124). The conductive layer (129) is very thin compared to the first dielectric layer (122) or the second dielectric layer (122). Even when the conductive layer (129) exists, the electric field and the interface surface charge density operate in the same manner.

It is preferable that the conductive layer (129) be exposed to the air gap. Referring to Fig. 27, when another dielectric layer (124) exists on the conductive layer (129), an interface charge is newly accumulated between the air gap (126) and the other dielectric layer (124).

Again, referring to FIG. 45, the filament (170) penetrates the first dielectric layer (122) to provide cooling gas to the air gap. The inner surface of the filament (170) may be coated with a conductive material.

The conductive layer (129) above accumulates an interface surface charge. The accumulated interface charge can be removed by being connected to ground through the conductive material and switch of the above-described path. The conductive layer (129) can be a semiconductor or a conductor. As the above-described path is coated with a conductive material, parasitic discharge can be suppressed.

According to a modified embodiment of the present invention, the conductive layer may be a photoresistive layer (e.g., CdS). Accordingly, when light is irradiated, the resistance of the photoresistive layer is reduced, so that interface degradation can be removed externally.

Figure 46 is a conceptual diagram showing an electrostatic device according to one embodiment of the present invention.

Referring to FIG. 46, the electrostatic device (700) has a first dielectric layer (122) and a second dielectric layer (124) laminated between a first electrode (110) and a second electrode (120). The first dielectric layer (122) has a first permittivity (ε1) and a first electrical conductivity (σ1), and has a thickness of d1. The second dielectric layer (124) has a second permittivity (ε2) and a first electrical conductivity (σ2), and has a thickness of d2. The protruding portion (128) may be made of the same or different material as the first dielectric layer. The second dielectric layer (124) may be an air gap or a vacuum gap.

The through hole (170) can be connected to the air gap by penetrating the first dielectric layer (122). An optical fiber (151) can be arranged in the through hole. The optical fiber (151) can provide visible light or ultraviolet light to the interface of the dielectric. Accordingly, the accumulated interface charge can be erased by the visible light or ultraviolet light.

The surface of the first dielectric layer providing the lower surface of the gap space may be roughened to allow light to diffuse.

An electrostatic device (700) according to one embodiment of the present invention includes an electrostatic electrode layer (110); a dielectric layer (122, 124) disposed on the electrostatic electrode layer; and a light providing unit (151) providing ultraviolet light to the dielectric layer (122, 124). A dechucking method of the electrostatic device includes a step of applying a first voltage (V0) to the electrostatic electrode layer; a step of removing the first voltage applied to the electrostatic electrode layer; a step of providing light to the dielectric layer through the light providing unit (151); and a step of erasing charges accumulated on the back surface of the dielectric layer or a substrate (120) disposed on the dielectric layer by the light.

The removal of the first voltage applied to the above electrostatic electrode layer and the provision of the light can be performed simultaneously. Accordingly, the interface charge is extinguished by the relaxation time and also by the generation of electrons and holes by the light.

The light can be provided after the first voltage applied to the electrostatic electrode layer is removed. For example, by using a voltage pulse having a polarity opposite to that of the first voltage to the electrostatic electrode, the interface charge can first be reduced or removed, and then the remaining interface charge can be additionally erased by light.

After the first voltage applied to the electrostatic electrode layer is removed, the interface charge can be additionally erased by simultaneously irradiating light while providing charges of opposite polarity to the electrostatic electrode layer using a voltage pulse having a polarity opposite to that of the first voltage.

While embodiments of the present invention have been described, these embodiments may be combined with one another.

Although the present invention has been illustrated and described with respect to certain preferred embodiments, the present invention is not limited to these embodiments, but includes various forms of embodiments that can be implemented by a person skilled in the art without departing from the technical idea of the present invention claimed in the claims.

110: 1st electrode
120: Second electrode
122: The first genome
124: The second genome

Claims (11)

An operating method of an electrostatic device comprising: an electrostatic electrode layer; and first and second dielectric layers sequentially arranged on the electrostatic electrode layer; and a power source for applying voltage to the electrostatic electrode layer,
The above power source applies a first voltage to adsorb the substrate on the second dielectric layer and accumulate a first interface charge between the first dielectric layer and the second dielectric layer; and
A step of applying a second voltage of opposite polarity to the first voltage to erase the first interface charge accumulated between the first dielectric layer and the second dielectric layer into a charge of opposite polarity,
The above first voltage and the above second voltage are alternately repeated,
An operating method of an electrostatic device, characterized in that the application time of the first voltage is shorter than the time constant of the first interface charge. In the first paragraph,
A method of operating an electrostatic device, characterized in that the second dielectric layer is an air gap. delete In the first paragraph,
The application time of the first voltage is the same as the application time of the second voltage,
An operating method of an electrostatic device, characterized in that the time constant of the first interface charge is 10 seconds or longer. An operating method of an electrostatic device including an electrostatic electrode layer; and first and second dielectric layers sequentially arranged on the electrostatic electrode layer; and a power source for applying voltage to the electrostatic electrode layer,
The above power source applies a first voltage to adsorb the substrate on the second dielectric layer and accumulate a first interface charge between the first dielectric layer and the second dielectric layer; and
A step of applying a second voltage of opposite polarity to the first voltage to erase the first interface charge accumulated between the first dielectric layer and the second dielectric layer into a charge of opposite polarity,
At the first voltage, the substrate is charged with a first charge,
An operating method of an electrostatic device, characterized in that the first interface charge is charged with a charge having the same sign as the first charge.
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