TWI787323B - Measuring device, measurement method, and plasma processing device - Google Patents

Abstract

A measuring device includes a switch that switches a connection of an electrode to which high frequency electric power is applied, wherein the electrode is within an electrostatic chuck disposed in a plasma processing device; a component provided with electrostatic capacitance, wherein the component is connected to the switch; and a measuring unit that measures a value corresponding to an electric charge amount accumulated in the component provided with the electrostatic capacitance.

Description

Measuring device, measuring method and plasma treatment device

The invention relates to a measuring device, a measuring method and a plasma processing device.

In the plasma treatment such as etching or film formation in the plasma treatment equipment, in order to control the etching rate or film formation rate, the key is to grasp the state of the plasma. Therefore, a method of measuring the self-bias voltage Vdc has been proposed in order to measure the state of the plasma (for example, refer to Patent Documents 1 and 2).

In Patent Document 1, the self-bias voltage Vdc is indirectly measured by a device not in direct contact with the plasma. In Patent Document 1, the device is installed in the wall of the processing container, the voltage applied to electrodes insulated by a dielectric in the device is measured, and the self-bias voltage Vdc is calculated by considering each parasitic capacitance from the measured voltage.

In Patent Document 2, a measurement circuit for the self-sufficient bias voltage Vdc is incorporated into the matcher, and the input resistance of the measurement circuit is set to a value sufficiently larger than the resistance value of the shower head, and the self-supply bias voltage is performed by the measurement circuit. Determination of Vdc.

[Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2001-148374

[Patent Document 2] Japanese Patent Laid-Open No. 2006-93342

However, the above-mentioned method needs to change the design of the device or the circuit, and cannot easily measure the self-sufficient bias voltage Vdc. For example, in Patent Document 1, the processing container wall is machined in order to install the device in the processing container wall. Also, since the measuring probe is located away from the plasma which is the measurement object, the sensitivity and accuracy of the measurement are lowered. In Patent Document 2, a measurement circuit for the self-sufficient bias voltage Vdc must be incorporated into the matching unit, and the design of the plasma processing device must be changed.

In view of the above, in Patent Documents 1 and 2, in order to incorporate a probe or a measurement circuit for measuring the self-sufficient bias voltage Vdc, it is necessary to change the mechanical design of the plasma processing device, high-frequency circuit (matching instrument) changes, there is a lack of versatility and simplicity of measurement.

In view of the above problems, in one aspect, the purpose of the present invention is to simply measure the plasma self-bias voltage Vdc.

In order to solve the above problems, according to one aspect, a measurement device is provided, which includes: a switching unit, which is an electrode disposed in an electrostatic chuck in a plasma processing device, and switches the connection of the electrode to which a DC voltage is applied; A member with electrostatic capacitance connected to the switching unit; and a measurement unit for measuring a value corresponding to the amount of charge stored in the member with electrostatic capacitance.

According to one aspect, the measurement of the plasma self-bias voltage Vdc can be easily performed.

1: Gas shower head

1a: Gas inlet

1b: Diffusion chamber

1c: Supply hole

2: carrier

2a: Electrostatic Chuck

2b: Abutment

3: The first high-frequency power supply

3a: Matcher

4: The second high-frequency power supply

4a: Matcher

5: Gas supply part

6: Relay box

6a: switch

7: DC power supply

8: Focus ring

9: Exhaust device

10: Measuring device

11: filter

12: Copper round plate

13: copper plate

14: Acrylic resin board

15: Probe

16: Surface potentiometer

17: Signal recording device

18: Potential measurement system

21: Adsorption electrode

22: Dielectric layer

22a: convex part

100: Plasma treatment device

200: control department

205:CPU

210:ROM

215: RAM

A: electrode

b _dot : area

d _dot : height

C: process container

C ₁ : Electrostatic capacitance

C ₂ : Electrostatic capacitance

C ₃ : Electrostatic capacitance

C ₁₁ : Electrostatic capacitance

C ₁₂ : Electrostatic capacitance

C ₁₃ : Electrostatic capacitance

C _B : DC blocking capacitor

G: gate valve

HF: 1st high frequency power

K: electrode

LF: 2nd high frequency power

q ₁ : charge

q ₂ : charge

q ₃ : charge

R: sediment

RF: High frequency power supply

S1~S6: steps

S10~S20: steps

T: height

Th ₁ : Threshold

Th ₂ : Threshold

V ₁ : Voltage

V ₂ : voltage

V _dc : Self-sufficient bias voltage

W: Wafer

Fig. 1(a), (b) are diagrams used to illustrate the self-sufficient bias voltage.

Fig. 2 is a diagram showing an example of a plasma processing device and a measuring device according to an embodiment.

Fig. 3 is a diagram for explaining the timing of measuring the self-bias voltage in one embodiment.

4( a ), ( b ) are diagrams showing an example of a measurement sequence of a self-bias voltage in one embodiment.

5( a ) to ( c ) are diagrams showing an example of the measurement sequence of the self-bias voltage in one embodiment.

FIG. 6 is a diagram showing an example of a model used for calculation of self-bias voltage in one embodiment.

Fig. 7 is a diagram showing an example of an equivalent circuit of a model of an embodiment.

Fig. 8 is a diagram showing an example of the measurement results of the self-bias voltage in one embodiment.

FIG. 9 is a diagram showing an example of information related to self-bias voltage and deposition time in one embodiment.

FIGS. 10( a ) to ( i ) are diagrams showing examples of measurements performed in advance to collect the relevant information in FIG. 9 .

Fig. 11 is a flow chart showing an example of a measuring method in one embodiment.

Hereinafter, modes for implementing the present invention will be described with reference to the drawings. In addition, in this specification and drawing, about the structure which is substantially the same, the description which overlaps is abbreviate|omitted by attaching the same code|symbol.

[Self Bias Voltage]

First, the DC self-bias voltage (hereinafter referred to as "self-bias voltage Vdc") of plasma will be described with reference to FIG. 1 . FIG. 1( a ) schematically shows a part of the counter electrode in which the electrode A and the electrode K are arranged to face each other. Electrode A is a ground electrode that is grounded, and electrode K is a high-frequency electrode that is connected to a high-frequency power supply (RF (Radio Frequency, radio frequency) power supply) via a DC blocking capacitor C _B . Also, the area of the electrode K is smaller than the area of the electrode A.

A high-frequency electric power RF is applied to the electrode K to dissociate and dissociate the gas, thereby generating plasma. Since the sinusoidal positive and negative symmetrical high-frequency power RF is applied to the electrode K, the potential of the electrode K is zero in total. Electrons and cations are generated from the generated plasma, and as shown in FIG. 1( b ), electrons flow into the electrode K when the electrode K is at a positive potential relative to the plasma, and cations flow into the electrode K when it is at a negative potential.

At this time, electrons can follow the high-speed potential change of the electrode K due to their small mass. That As a result, electrons flow into the electrode K. On the other hand, the positive ions cannot follow the high-speed potential change of the electrode K due to their large mass, and move in the average electric field according to the law of inertia. Therefore, the inflow of ions to the electrode K is constant and extremely small.

Since the electrode K is floating from the ground by the DC blocking capacitor C _B , the electrons flowing into the electrode K do not flow to the ground. Thus, electrons flow into and are stored in the electrode K during the period (half cycle) in which the surface of the electrode K is at a positive potential relative to the plasma. However, the surface of electrode K is negatively charged by the stored electrons, thereby negatively biasing the plasma. Due to the negative bias, cations flow into the surface of the electrode K. Thereby, a sheath layer is formed on the surface of the electrode K.

Finally, the surface of the electrode K becomes a positive potential with respect to the plasma in a very short time in one cycle. At this time, the DC (Direct Current) component of the potential difference of the electrode K when the electrons flowing in and the positive ions stably flowing in due to the negative bias are in balance is the self-bias voltage Vdc.

In order to control the etching rate or film formation rate, etc., which represent the characteristics of plasma processing, it is necessary to grasp the state of the plasma. Therefore, in this embodiment, in order to grasp the state of the plasma in the plasma processing apparatus 100, the self-bias voltage Vdc is measured.

[Structure of plasma treatment device]

The plasma processing apparatus 100 of this embodiment shown in FIG. 2 has the apparatus main body, the relay box 6, and the measuring apparatus 10. The measurement device 10 measures the voltage of the adsorption electrode 21 in the electrostatic chuck 2 a arranged in the processing container C of the plasma processing device 100 . The relay box 6 switches the connection destination of the adsorption electrode 21 between the DC power supply 7 and the measurement device 10 . If the adsorption electrode 21 is connected to the measuring device 10, the measuring device 10 measures the voltage V2 between the copper circular plate 12 and the copper plate ₁₃ as the DC component of the potential difference of the adsorption electrode 21 of the electrostatic chuck 2a, and calculates the self-bias based on the measurement result. The voltage Vdc, the above _- mentioned voltage V2 represents a value corresponding to the amount of charge stored in the acrylic resin plate 14 sandwiched between the copper circular plate 12 and the copper plate 13. Therefore, in this embodiment, by adding the relay box 6 and the measuring device 10 to the existing plasma processing apparatus 100, the measurement of the self-bias voltage Vdc can be performed simply and accurately. Hereinafter, an example of the configuration of the plasma processing apparatus 100 and the measurement apparatus 10 of this embodiment will be described.

(Structure of plasma treatment device)

The plasma processing device 100 of this embodiment is a capacitively coupled parallel plate plasma processing device, and has a substantially cylindrical processing container C. The inner surface of the processing container C is subjected to aluminum oxide film treatment (anodizing treatment). The inside of the processing container C serves as a processing chamber for plasma processing such as etching processing or film forming processing using plasma. In the processing container C, the stage 2 is installed.

In the stage 2, an electrostatic chuck 2a for electrostatically adsorbing the wafer W is provided on the base 2b. The base 2 b is formed of, for example, aluminum (Al), titanium (Ti), silicon carbide (SiC), or the like. The stage 2 also functions as a lower electrode.

The electrostatic chuck 2 a has a structure having an adsorption electrode 21 in a dielectric layer 22 . Dot-shaped protrusions 22a are formed on the surface of the electrostatic chuck 2a. The adsorption electrode 21 is connected to the relay box 6 . When the switch 6a of the relay box 6 is switched to the DC power supply 7, and a DC voltage is supplied from the DC power supply 7 to the chucking electrode 21, the wafer W as an example of a substrate is sucked and held by the electrostatic chuck 2a by Coulomb force.

An annular focus ring 8 is placed on the upper portion of the outer peripheral side of the electrostatic chuck 2 a so as to surround the outer edge of the wafer W. The focus ring 8 is formed of silicon, for example, and functions to converge the plasma toward the surface of the wafer W to improve plasma processing efficiency.

To the stage 2, the first high-frequency power (HF) for plasma generation of the first frequency is applied from the first high-frequency power supply 3, and the second high-frequency power (HF) which is a frequency lower than the first frequency is applied from the second high-frequency power supply 4. The second high-frequency power (LF) is used for generating the bias voltage of 2 frequencies. The first high-frequency power supply 3 is electrically connected to the stage 2 through a matching device 3a. The second high-frequency power supply 4 is electrically connected to the stage 2 through a matching device 4a. The first high-frequency power supply 3 applies, for example, high-frequency power HF of 40 MHz to the stage 2 . The second high-frequency power supply 4 applies, for example, high-frequency power LF of 13.56 MHz to the stage 2 . In addition, in the present embodiment, the first high-frequency power is applied to the stage 2 , but the first high-frequency power may be applied to the gas shower head 1 .

The matching unit 3 a matches the load impedance with the internal (or output) impedance of the first high-frequency power supply 3 . The matching unit 4a matches the load impedance with the internal (or output) impedance of the second high-frequency power supply 4 .

The gas shower head 1 is installed so as to close the opening of the ceiling wall of the processing container C through a shield ring covering the outer edge thereof. The gas shower head 1 is grounded. The gas shower head 1 can be formed of silicon. The gas shower head 1 functions as a counter electrode (upper electrode) facing the stage 2 (lower electrode).

In the gas shower head 1, a gas introduction port 1a for introducing gas is formed. Inside the gas shower head 1, a diffusion chamber 1b for diffusing gas is provided. The gas output from the gas supply part 5 is supplied to the diffusion chamber 1b through the gas introduction port 1a, diffuses in the diffusion chamber 1b, and is introduced into the processing container C from the plurality of gas supply holes 1c.

An exhaust port is formed on the bottom surface of the processing container C, and the inside of the processing container C is exhausted by an exhaust device 9 connected to the exhaust port. Thereby, the inside of the processing container C can be maintained at a specific vacuum degree. A gate valve G is provided on the side wall of the processing container C. The gate valve G is opened and closed when carrying in and carrying out the wafer W from the processing container C.

When the processing gas is supplied from the gas supply unit 5 into the processing container C and the first and second high-frequency powers are applied to the stage 2 from the first high-frequency power supply 3 and the second high-frequency power supply 4, plasma is generated, and the crystal Circle W is subjected to specific plasma treatment. In particular, when the second high-frequency power is applied to the stage 2 from the second high-frequency power supply 4, ions in the plasma are drawn toward the wafer W side.

After the plasma treatment, the DC power supply 7 supplies the adsorption electrode 21 with a DC voltage opposite to that of the wafer W during adsorption, thereby removing the charge of the wafer W. Thereby, the wafer W is peeled off from the electrostatic chuck 2a, and carried out from the gate valve G to the outside of the processing container C. As shown in FIG.

The control part 200 which controls the operation of the whole apparatus is provided in the plasma processing apparatus 100. The control unit 200 has a CPU (Central Processing Unit, central processing unit) 205 , a ROM (Read Only Memory, read only memory) 210 and a RAM (Random Access Memory, random access memory) 215 . The CPU 205 executes required processes such as etching according to the recipes stored in memory areas such as the RAM 215 . In the process recipe, the control information of the device for the process conditions is set, namely, the program time, pressure (gas exhaust), high-frequency power or voltage, various gas flow rates, and the temperature in the processing container (the temperature of the upper electrode, the temperature of the side wall of the processing container, Wafer W temperature, electrostatic chuck temperature, etc.), refrigerant temperature, etc.

In addition, the control unit 200 switches the switch 6 a of the relay box 6 at a specific timing to connect the adsorption electrode 21 to the measurement device 10 . The voltage V ₂ measured by the measuring device 10 is sent to the control unit 200 , whereby the control unit 200 calculates the self-bias voltage Vdc based on the voltage V ₂ .

Furthermore, a recipe representing a program or processing conditions for executing these operations can also be stored in a hard disk or a semiconductor memory. In addition, the process recipe can also be stored in CD-ROM (compact disc read only memory, CD-ROM), DVD (Digital Versatile Disc, digital versatile disc) and other portable storage media that can be read by the computer. at a specific location and read out.

(Configuration of measuring device)

Next, an example of the configuration of the measurement device 10 will be described. The measurement device 10 has a filter 11 , a copper disc 12 , a copper plate 13 , an acrylic resin plate 14 , a probe 15 , a surface potentiometer 16 , and a signal recording device 17 . The probe 15 and the surface potentiometer 16 constitute a potential measurement system 18 .

In addition, in FIG. 2 , for convenience of description, the relay box 6 is shown separately from the measurement device 10 , but the measurement device 10 has the relay box 6 . The relay box 6 switches the connection of the adsorption electrode 21 between the DC power supply 7 and the components having electrostatic capacitance of the measurement device 10 . The relay box 6 connects the switch 6 a of the relay box 6 to the measurement device 10 at the timing of measuring the self-sufficient bias voltage Vdc. The relay box 6 is an example of a switching unit that switches the connection of the adsorption electrode 21 to which high-frequency power is applied to a member having electrostatic capacitance. A member having a structure in which an acrylic resin plate 14 is sandwiched between the copper circular plate 12 and the copper plate 13 is an example of a member having an electrostatic capacitance. Components with electrostatic capacitance and It is not limited to the composition of the copper circular plate 12, the copper plate 13, and the acrylic resin plate 14, and may be composed of insulated conductors.

In the potential measuring system 18 , the potential of the acrylic resin plate 14 generated between the copper circular plate 12 and the copper plate 13 is measured by the surface potentiometer 16 using the probe 15 provided in non-contact with the surface of the copper circular plate 12 . The potential measuring system 18 is an example of a measuring unit that measures a value corresponding to the amount of charge stored in a member having electrostatic capacitance. As long as the potential difference between the copper circular plate 12 and the copper plate 13 can be measured, the probe 15 may be in contact with the copper circular plate 12 or not.

A filter 11 for removing high-frequency power is provided between the relay box 6 and components having electrostatic capacitance to prevent the high-frequency power from propagating to the measuring device 10 side. If the switch 6a of the relay box 6 is switched from the side connected to the DC power supply 7 to the side connected to the component with the electrostatic capacity of the measuring device ₁₀ , the measurement of the voltage V2 generated in the component with the electrostatic capacity can be performed, That is, the measurement of the voltage V2 of the adsorption electrode ₂₁ in the floating state.

Specifically, the copper plate 13 is grounded, and the potential measured by the surface potentiometer 16 using the probe 15 provided in non-contact with the surface of the copper circular plate 12 becomes the voltage V ₂ of the adsorption electrode 21 in a floating state. Furthermore, the diameter of the copper circular plate 12 may be, for example, about 100 mm, but it is not limited thereto.

The voltage V ₂ measured by the surface potentiometer 16 is stored in the signal recording device 17 connected to the surface potentiometer 16 . The signal recording device 17 can be an electronic machine with a memory such as a PC (Personal Computer) or a tablet terminal, or can be a cloud computer installed on the cloud. The measurement voltage V2 recorded by the signal recording device ₁₇ is sent to the control unit 200, and is used by the control unit 200 to control the etching rate or film formation rate of the plasma processing device 100, etc.

The amount of charge stored in components with electrostatic capacitance will be affected by moisture. Therefore, the copper circular plate 12, the copper plate 13, the acrylic resin plate 14 and the probe 15 are preferably arranged in a vacuum container. By placing the copper circular plate 12, the copper plate 13, the acrylic resin plate 14, and the probe 15 in a vacuum environment, the voltage V ₂ can be accurately measured without being affected by environmental disturbances.

[measurement timing]

FIG. 3 shows an example of a processing cycle for processing a wafer W in the plasma processing apparatus 100 . When the process starts, first, the wafer W is carried in from the gate valve G of the plasma processing apparatus 100 (step S1). Next, a specific DC voltage is supplied to the adsorption electrode 21 from the DC power supply 7 to electrostatically adsorb the wafer W to the electrostatic chuck 2a (step S2). Next, high-frequency power is applied to the stage 2 (adsorption electrode 21 ), and the process gas supplied from the gas supply unit 5 is plasma-formed to perform plasma processing such as etching on the wafer W (step S3 ). Etching treatment is an example of substrate treatment using plasma. The high-frequency power may be either the high-frequency power HF output from the first high-frequency power supply 3 or the high-frequency power LF output from the second high-frequency power supply 4 , or both.

Next, supply the DC voltage opposite to the DC voltage applied to the adsorption electrode 21 in step S2 and the same magnitude to the adsorption electrode 21, so that the wafer W is detached from the electrostatic chuck 2a (step S4), and the wafer W is removed from the plasma. The gate valve G of the processing device 100 is carried out (step S5). Next, cleaning processing is performed (step S6).

At this point in time, the processing of one wafer W ends, and one processing cycle is completed. open again When the processing cycle of the next wafer W is started, the surface treatment of the electrostatic chuck 2a (cleaning of processing agent, etc.) is carried out (step S6), the next wafer W is loaded (step S1), and the processing after step S1 is repeated.

In the above cycle (1) cleaning treatment ( S6 ) and (2) etching treatment ( S3 ), the relay box 6 switches the connection of the adsorption electrode 21 to the measuring device 10 . That is, the relay box 6 switches the connection of the adsorption electrode 21 to the measurement device 10 at a timing during the processing or cleaning process of the wafer W using plasma, and the adsorption electrode 21 in a floating state is measured in the potential measurement system 18 The voltage V ₂ .

[measurement sequence]

Next, an example of the measurement sequence of (1) cleaning treatment and (2) etching treatment will be described with reference to the measurement sequence diagrams of FIGS. 4 and 5 . Fig. 4 shows an example of a measurement sequence for cleaning treatment. FIG. 5 shows an example of a measurement sequence of etching processing. Control of the measurement sequence of the cleaning process and the etching process is performed by the control unit 200 .

(1) Determination sequence of cleaning treatment

The measured sequence of cleaning processes shown in FIG. 4 was performed in either wafer-less dry cleaning (WLDC) or wafer-less processing (WLT). At the start of this measurement sequence, the adsorption electrode 21 is in a state of being disconnected, that is, not connected to the DC power supply 7 but connected to the ground (reference potential).

In this state, the measurement sequence is started at I in FIG. 4 , and the switch 6 a of the relay box 6 is switched to the side connected to the measurement device 10 at II. Thereby, the connection of the adsorption electrode 21 is switched to the measurement device 10, and the adsorption electrode 21 becomes a floating state.

Afterwards, turn on the high-frequency power in III, use the probe 15 in the potential measurement system 18 to measure the voltage V ₂ of the copper disc 12 through the surface potentiometer 16, and record it in the signal recording device 17. Next, disconnect the high-frequency power at IV, switch the switch 6a of the relay box 6 to the side connected to the DC power supply 7 at V, and end the measurement sequence. The above measurement sequence was repeated.

(2) Determination sequence of etching treatment

The measurement sequence of the etching process shown in FIG. 5 is performed by placing the wafer W on the electrostatic chuck 2 a and performing plasma processing such as etching. At the start of this measurement sequence, the adsorption electrode 21 is turned on, that is, connected to the DC power supply 7 .

In this state, the measurement sequence is started at I in FIG. 5 , and the switch 6 a of the relay box 6 is switched to the side connected to the measurement device 10 at II. Thereby, the connection of the adsorption electrode 21 is switched to the measurement device 10, and the adsorption electrode 21 becomes a floating state.

Afterwards, turn on the high-frequency power at III, use the probe 15 in the potential measurement system 18 to measure the voltage V ₂ of the copper disc 12 through the surface potentiometer 16, and record it in the signal recording device 17. Next, disconnect the high-frequency power at IV, and switch the switch 6a of the relay box 6 to the side connected to the DC power supply 7 at V, and the measurement sequence ends. When the above measurement sequence is repeated, if it is in the process of plasma treatment, apply a direct current voltage HV to the adsorption electrode 21 at VI, so that the wafer W is electrostatically adsorbed on the stage 2, and then perform the measurement sequence of VII~XI, and at XII cuts off the application of the DC voltage HV to the adsorption electrode 21, thereby stopping the adsorption of the wafer W. The determination sequences of VII~XI are the same as those of II~V described above.

In this way, the relay box 6 switches the connection of the adsorption electrode 21 between the DC power supply 7 and the measurement device 10 . When the switch 6a of the relay box 6 is switched to the measurement device 10, the adsorption electrode 21 will be in a floating state, and then high-frequency power is applied to plasmaize the gas in the plasma processing space of the plasma processing device 100.

After the high-frequency power is applied, the surface potentiometer 16 uses the probe 15 to measure the voltage V ₂ of the copper disc 12 , and the control unit 200 calculates the self-bias voltage Vdc based on the measured voltage V ₂ . Hereinafter, a method of calculating the self _- bias voltage Vdc based on the measured voltage V2 will be described.

[Calculation method of self-bias voltage Vdc]

An example of the model used for the calculation of the self-bias voltage Vdc of this embodiment is shown in FIG. 6 . As shown in the enlarged view of a part of the surface of the electrostatic chuck _2a in FIG. d _dot . Also, let T be the height from the adsorption electrode 21 to the upper surface of the dot, and let a _el be the area ratio of the upper surface area of the protrusion 22a to the surface area of the electrostatic chuck 2a.

Let the electrostatic capacitance of the space between the point-shaped convex parts 22a of the electrostatic chuck 2a be C11, set the electrostatic capacitance between the space below the convex parts 22a and the adsorption electrode ₂₁ as C12, and set the capacitance _of the convex part 22a The capacitance between the upper surface and the adsorption electrode 21 is set as C ₁₃ .

The capacitance C11 is calculated by the following formula ( ₁ ).

[Formula 1]

_The capacitance C12 is calculated by the following formula (2).

The capacitance _C13 is calculated by the following formula (3).

In formulas (1) to (3), ε ₀ represents the dielectric constant of vacuum, and ε _r represents the specific permittivity, that is, the dielectric constant ε of the dielectric layer 22 of the electrostatic chuck 2a and the dielectric constant ε of vacuum ₀ (=ε/ε ₀ ), and S represents the area of the adsorption electrode 21 .

Since the electrostatic capacitances C ₁₁ , C ₁₂ , and C ₁₃ are fixed values obtained according to the design parameters, the electrostatic capacitance C ₁ of the electrostatic chuck 2a is obtained by substituting the electrostatic capacitances C ₁₁ , C ₁₂ , and C ₁₃ into the following (4 ) formula and calculated in the form of a fixed value.

[Formula 4]

Using the calculated electrostatic capacitance C ₁ of the electrostatic chuck 2a, the voltage V ₁ applied to the electrostatic chuck 2a shown in FIG. ₇ as the equivalent circuit of the model in FIG. Coulomb's law, the relationship of the following formula (5) is established.

C ₁ V ₁ =q ₁ ‧‧‧(5)

Set the electrostatic capacitance between the copper round plate 12 and the copper plate 13 (ground) as C ₂ , set the electrostatic capacitance of the filter 11 as C ₃ , and apply it between the copper round plate 12 and the copper plate 13 and the filter 11 The voltage is set to V ₂ . Also, if the charges stored between the copper circular plate 12 and the copper plate 13 and the filter 11 are respectively q ₂ and q ₃ , then the relationship of the following formula (6) holds true according to Coulomb's law.

Furthermore, the electrostatic capacitance _C2 is a fixed value determined by the configuration of the copper circular plate 12, the copper plate 13, and the acrylic resin plate 14 and obtained according to design parameters. Similarly, the capacitance C3 is a fixed value obtained from design parameters determined by the configuration _of the filter 11 . Furthermore, the electrostatic capacitances C ₁ , C ₂ , and C ₃ can not only be fixed values determined by design parameters, but also be determined by actual measured values obtained through measurement.

(C ₂ +C ₃ )V ₂ =q ₂ +q ₃ ‧‧‧(6)

For the charge q 1 stored in the electrostatic chuck 2a, the charge q ₂ stored between the copper circular plate 12 and the copper plate 13, and the charge q ₃ stored in the filter ₁₁ , the relationship of the following formula (7) holds true.

q ₁ -(q ₂ +q ₃ )=0‧‧‧(7)

If the formula (7) is transformed, then q ₁ =(q ₂ +q ₃ )‧‧‧(8)

If formula (5) and formula (6) are substituted into formula (8), then C ₁ V ₁ =(C ₂ +C ₃ )V ₂ ‧‧‧(9)

If formula (9) is transformed, then V ₁ =V ₂ ×(C ₂ +C ₃ )/C ₁ ‧‧‧(10)

V ₂ =V ₁ ×C ₁ /(C ₂ +C ₃ )‧‧‧(11)

The self-sufficient bias voltage V _dc in Fig. 7 is calculated by formula (12) according to formula (10) and formula (11).

V _dc =V ₁ +V ₂ ‧‧‧(12)

If formula (10) is substituted into formula (12), then V _dc =V ₂ ×(C ₂ +C ₃ )/C ₁ +V ₂ ‧‧‧(13)

By substituting the voltage V ₂ measured by the measuring device 10 and the fixed capacitances C ₁ , C ₂ , and C ₃ into the formula (13), the self-bias voltage V _dc is calculated. Capacitance C ₁ is the composite capacitance value of C ₁₁ , C ₁₂ , and C ₁₃ obtained from formula (4). The electrostatic capacitances C ₁ , C ₂ , and C ₃ are fixed values determined by design parameters.

As explained above, according to the measurement method of this embodiment, the self-sufficient bias voltage V _dc can be based on the formula (13) from the measured value of the surface potentiometer 16, that is, the voltage V ₂ , the capacitance C 1 of the electrostatic chuck 2a, and the electrostatic capacity C ₁ of the electrostatic chuck 2a. The electrostatic capacitance C _{2 of the capacitance component and the electrostatic capacitance C 3 of} the filter 11 are derived easily and accurately.

[The measurement results]

FIG. ₈ shows the measurement results of the voltage V2 obtained by the measurement device 10 of this embodiment, and an example of the self _- bias voltage _Vdc calculated from the voltage V2. The horizontal axis of FIG. 8 represents the pressure in the processing container C of the plasma processing apparatus 100 . In FIG. 8 , the voltage V2 measured by the measuring device ₁₀ by changing the pressure in the processing container C is shown as a measured value. Also, the self-bias voltage V _dc converted from the capacitances C ₁ , C ₂ , and C ₃ and the measured voltage V ₂ based on the formula (13) is expressed as a converted value.

Thereby, no matter how the pressure in the processing container C changes, the measured values at the three points correspond to the converted values in a one-to-one correspondence. That is, it is understood that the potential measurement system 18 can measure the voltage of the adsorption electrode 21 in a floating state using a member having electrostatic capacitance, and calculate the self-bias voltage V _dc with high accuracy using the measured voltage V ₂ . Also, according to formula (13), the smaller the electrostatic capacitance C2 of the member with electrostatic capacitance and the electrostatic capacitance C3 _of the filter ₁₁ , the smaller the measured voltage V2 ₍ measured value) and the self-supply bias voltage _Vdc (converted value) ) is closer.

As explained above, according to this embodiment, the self-bias voltage V _dc of the plasma can be easily adjusted by simply installing the switching unit and the measuring device in the plasma processing apparatus without changing the design of the plasma processing apparatus. Determination.

[test methods]

The deflection or cracking of the wafer W is caused by the charge remaining on the surface of the electrostatic chuck 2a. The self-bias voltage V _dc can be calculated by measuring the voltage V ₂ by the measuring device 10 based on the formula (13). The above voltage V ₂ represents the residual adsorption state on the surface of the electrostatic chuck 2a that causes the wafer W to shift or break, That is, the ease of storage of charge or the state of charge.

The measurement of the voltage V ₂ and the calculation of the self-bias voltage V _dc are performed in the state of the electrostatic chuck 2 a before the wafer W is loaded. Moreover, according to the calculated self-sufficient bias voltage V _dc , the residual adsorption state on the surface of the electrostatic chuck 2a at that time point is judged, and the cleaning treatment time of the electrostatic chuck 2a is controlled or whether the maintenance of the electrostatic chuck 2a performed by opening the processing container C is performed. Wait. In this way, by pre-determining the residual adsorption state on the surface of the electrostatic chuck 2a based on the calculated self-bias voltage V _dc without placing the wafer W, it is possible to eliminate the possibility of causing the wafer W to rise due to the lift of the pusher pin when the wafer W is unloaded. Risk of circle W breaking.

That is, conventionally, the magnitude of the pin torque when the pusher pin is raised when the wafer W is unloaded was checked to confirm the residual suction, or a probe or a sensor was inserted to measure the surface potential of the electrostatic chuck 2a. On the other hand, according to the above measuring method, the risk of cracking of the wafer W can be prevented, and the residual adsorption state on the surface of the electrostatic chuck 2a can be judged based on the value of the self-bias voltage V _dc to judge whether to perform maintenance. In this way, based on the judgment result, the guidelines for optimizing and improving the operation method such as the frequency of cleaning performed, the cleaning processing time, and the execution timing of other maintenance can be obtained according to the self-sufficient bias voltage V _dc .

For example, an example of a measurement method including an embodiment of the above determination will be described with reference to FIGS. 9 to 11 . FIG. 9 is a graph showing an example of information related to self-bias voltage V _dc and deposition time in one embodiment. FIG. 10 is a diagram showing an example of a preliminarily performed process for collecting information related to an example shown in the graph of FIG. 9 . Fig. 11 is a flow chart showing an example of a measuring method in one embodiment.

FIG. 9 is based on the measured voltage V ₂ between the copper circular plate 12 and the copper plate 13 to derive the cumulative value of the deposition time on the horizontal axis and the relevant information on the self-bias voltage V _dc on the vertical axis. The cumulative value of the deposition time of the deposit on the horizontal axis is equal to the cumulative value of the application time of the high-frequency power applied for supplying the deposition gas, and is proportional to the thickness of the deposit deposited on the surface of the electrostatic chuck 2a. The cumulative value of the deposition time on the horizontal axis is an example of the value representing the residual adsorption state of the electrostatic chuck 2a. However, the value indicating the residual adsorption state of the electrostatic chuck 2a is not limited to the cumulative value of the deposition time, but may also be a measured value of the thickness of the deposit on the electrostatic chuck 2a, or a cumulative value of the application time of high-frequency power.

In addition, the self-bias voltage V _dc on the vertical axis is an example of a value corresponding to the above-mentioned measured charge amount. The value corresponding to the measured charge amount is not limited to the self-bias voltage V _dc calculated from the voltage V ₂ , and may be the measured voltage V ₂ .

In this embodiment, the accumulation value of the deposition time in FIG. 9 and the relevant information of the self-bias voltage V _dc are derived from the process of (a) to (i) in FIG. 10 . However, the curve representing the correlation between the value corresponding to the measured charge amount and the value representing the residual adsorption state of the electrostatic chuck 2a is not limited to a straight line.

For example, in the process shown in Figure 10(a), the measurement device 10 places the wafer W on the electrostatic chuck 2a in a state where no deposits exist on the surface (that is, the deposition time is 0 seconds), generates a plasma of oxygen, and measures The voltage V ₂ between the copper circular plate 12 and the copper plate 13 . Then, based on the formula (13), the self-bias voltage _Vdc representing the residual adsorption state _on the surface of the electrostatic chuck 2a at the initial stage was calculated from the voltage V2 of the measurement result. The data at this time is V _dc (=-70V) when the deposition time in FIG.

Next, in the process of FIG. 10(b), after the wafer W is unloaded, a CF-based gas as an example of a deposition gas is supplied and applied for a predetermined time (30 seconds in this embodiment) while the wafer W is unloaded. The high-frequency power generates the plasma of the CF-based gas, so that the CF-based polymer, that is, the deposit R, is deposited on the surface of the electrostatic chuck 2a.

Next, in the manufacturing process of FIG. 10(c), the wafer W is placed on the electrostatic chuck 2a to generate oxygen plasma, and the voltage V ₂ between the copper circular plate 12 and the copper plate 13 is measured. Then, based on the formula (13), the self-bias voltage _Vdc representing the residual adsorption state _on the surface of the electrostatic chuck 2a at that point in time was calculated from the voltage V2 of the measurement result. The data at this time is V _dc (=-68V) when the deposition time in FIG.

Next, in the process shown in FIG. 10( d ), after unloading the wafer W, the CF-based gas is generated by applying high-frequency power for a specific period of time (30 seconds in this embodiment) while supplying the CF-based gas. slurry, so that the deposit R of the CF-based polymer is further deposited on the surface of the electrostatic chuck 2a.

Next, in the manufacturing process of FIG. 10( e ), the wafer W is placed on the electrostatic chuck 2 a to generate oxygen plasma, and the voltage V ₂ between the copper circular plate 12 and the copper plate 13 is measured. Then, based on the formula (13), the self-bias voltage _Vdc (= _-66V ) representing the residual adsorption state on the surface of the electrostatic chuck 2a at that point in time was calculated from the voltage V2 of the measurement result. The data at this time is the V _dc when the deposition time in FIG. 9 is 60 seconds (=30+30), and this data is stored in the RAM215 of the control part 200 and other memory parts.

In the process of Fig. 10(f) and (g), Fig. 10(h) and (i), the same operation as that of Fig. 10(c) and Fig. 10(d) is repeated twice. That is, in the measurement of Fig. 10(g), the V _dc (=-64V) when the deposition time of Fig. 9 is calculated as 90 seconds, and in the measurement of Fig. 10(h), the deposition time of Fig. 9 is calculated as 120 seconds When V _dc (=-62V), these data are memorized in memory parts such as RAM215 of the control part 200 .

By performing this measurement in advance, relevant information showing the correlation between the deposition time and the self-bias voltage V _dc shown as an example in FIG. 9 is stored in the memory unit. Furthermore, the relevant information showing the correlation between the deposition time and the self-bias voltage V _dc in FIG. 9 is the relevant information showing the correlation between the value corresponding to the amount of charge measured in advance and the value showing the residual adsorption state of the electrostatic chuck 2a. One example.

The relevant information in FIG. 9 stored in this way is for reference by the measurement method of an embodiment shown in FIG. 11 . The measurement method shown in FIG. 11 is executed by the control unit 200 before loading the wafer W, and includes a process of determining whether to perform maintenance such as cleaning processing. Thus, according to the measurement method of this embodiment, since maintenance such as cleaning treatment is performed before loading the wafer W in a specific case, it is possible to prevent the wafer W from shifting or cracking due to residual adsorption on the surface of the electrostatic chuck 2a. .

When the process in FIG. 11 starts, the control unit 200 switches the switch 6 a of the relay box 6 to connect the adsorption electrode 21 to the measurement device 10 . The measuring device 10 measures the voltage V ₂ (step S10). The measured voltage V2 is sent to the control unit ₂₀₀ , whereby the control unit ₂₀₀ calculates the self-bias voltage Vdc based on the voltage _V2 (step S12).

Next, the control unit 200 judges whether or not the calculated absolute value of the self-bias voltage V _dc exceeds a predetermined threshold Th ₁ (step S14). If the control unit 200 determines that the calculated absolute value of V _dc does not exceed the predetermined threshold Th ₁ , it determines that the residual adsorption state of the electrostatic chuck 2a is not to the extent that wafer cracks occur when the wafer W is destaticized and unloaded, thereby End this processing.

On the other hand, if in step S14, the control unit 200 determines whether the absolute value of the calculated self-bias voltage V _dc exceeds the predetermined threshold Th ₁ , then it is determined whether the absolute value of the self-bias voltage V _dc exceeds the predetermined threshold Th ₂ (step S16).

For example, as shown in FIG. ₁₁ , the threshold Th1 and the threshold Th2 have _a relationship in which the absolute value of the threshold _Th1 is smaller _than the absolute value of the threshold Th2. For example, the threshold Th1 is _an example of an index indicating that when the absolute value of the self-supplied bias voltage V _dc is greater than the threshold Th1, the pin torque _of the push rod pin is increased, and the crystal may sometimes be damaged during destaticization. Circle W is the residual adsorption state to the extent that rupture occurs.

Also, for example, the threshold value Th2 is an example of an index indicating that when the absolute value of the self _- bias voltage _Vdc is greater than the threshold value Th2, there is a high possibility of cracks occurring _on the wafer W during destaticization. The adsorption state remains, and the processing container C must be opened for maintenance.

Therefore, if in step S16, the control unit 200 determines that the absolute value of the self-sufficient bias voltage V _dc exceeds the predetermined threshold value Th ₂ , it will open the processing container C and perform maintenance such as alcohol wiping on the surface of the electrostatic chuck 2a. Control, and end this process.

On the other hand, if in step S16, the control unit 200 determines that the absolute value of the self-sufficient bias voltage V _dc does not exceed the predetermined threshold value Th ₂ , then the method of making the cleaning process longer than usual and performing dry cleaning without wafers Control is performed, and this process ends. As an example of making the cleaning processing time longer than usual, for example, when the normal cleaning processing time is 20 seconds, control to extend it to about 80 seconds is exemplified.

In this way, the determination of the residual adsorption state on the surface of the electrostatic chuck 2a is performed based on the self _- bias voltage _Vdc calculated from the measured voltage V2 by referring to the memory portion storing information about the self-bias voltage _Vdc and the deposition time. Process. Then, in the determination process, when the absolute value of the measured and calculated self _- bias voltage V _dc exceeds at least _one of the predetermined threshold value Th1 or threshold value Th2 with reference to the above-mentioned memory unit, the control unit 200 determines that the electrostatic chuck is to be executed. 2a or cleaning treatment or other maintenance in the treatment container C. Furthermore, in the determination process, the residual adsorption state on the surface of the electrostatic chuck 2a can also be determined based _on the measured voltage V2.

In this way, based on the calculated self-bias voltage V _dc , guidelines for optimizing and improving the operation method can be obtained, such as cleaning frequency or cleaning time, whether it is the timing for performing maintenance of the electrostatic chuck 2a, etc.

Above, the measuring device, measuring method and plasma processing device have been described by the above-mentioned embodiment, but the measuring device, measuring method and plasma processing device of the present invention are not limited to the above-mentioned embodiment, and can be used within the scope of the present invention. Various changes and improvements have been made. The matters described in the above-mentioned plural embodiments can be combined within the range that does not contradict.

The substrate processing device of the present invention can be applied to capacitively coupled plasma (CCP, Capacitively Coupled Plasma), inductively coupled plasma (ICP, Inductively Coupled Plasma), radial line slot antenna, electron cyclotron resonance plasma (ECR, Electron Any type of Cyclotron Resonance Plasma), Helicon Microwave Plasma (HWP, Helicon Wave Plasma).

In this specification, a wafer W has been described as an example of a substrate. However, the substrate is not limited thereto, and may also be various substrates for LCD (Liquid Crystal Display), FPD (Flat Panel Display, flat panel display), or a photomask, CD (Compact Disc, optical disc) substrate, printed Substrate etc.

1‧‧‧Gas shower head

1a‧‧‧Gas inlet

1b‧‧‧diffusion chamber

1c‧‧‧Supply hole

2‧‧‧carrier

2a‧‧‧Electrostatic chuck

2b‧‧‧abutment

3‧‧‧The first high-frequency power supply

3a‧‧‧Matcher

4‧‧‧The second high frequency power supply

4a‧‧‧Matcher

5‧‧‧Gas Supply Unit

6‧‧‧Relay box

6a‧‧‧Switch

7‧‧‧DC power supply

8‧‧‧Focus ring

9‧‧‧exhaust device

10‧‧‧measurement device

11‧‧‧Filter

12‧‧‧copper round plate

13‧‧‧copper plate

14‧‧‧Acrylic resin board

15‧‧‧Probe

16‧‧‧Surface potentiometer

17‧‧‧Signal recording device

18‧‧‧potential measurement system

21‧‧‧Adsorption electrode

22‧‧‧dielectric layer

22a‧‧‧convex part

100‧‧‧plasma treatment device

200‧‧‧Control Department

205‧‧‧CPU

210‧‧‧ROM

215‧‧‧RAM

C‧‧‧Disposal container

G‧‧‧gate valve

HF‧‧‧The first high-frequency power

LF‧‧‧The second high-frequency power

V ₂ ‧‧‧voltage

W‧‧‧Wafer

Claims (14)

A measurement device comprising: a switching unit, which is an electrode arranged in an electrostatic chuck in a plasma processing device, and switches the connection of the electrode to which a DC voltage is applied; a member having an electrostatic capacitance, which is connected to the switching unit and a measuring section that measures a value corresponding to the amount of charge stored in the above-mentioned member with electrostatic capacitance; Capacitive member; during the process of performing the above-mentioned substrate processing, the above-mentioned measurement unit measures the above-mentioned value corresponding to the above-mentioned electric charge accumulated on the above-mentioned member with electrostatic capacitance. The measurement device according to claim 1, wherein the switching unit switches the connection of the electrodes between the DC power supply and the member having electrostatic capacitance. The measuring device according to claim 1 or 2, which has a filter for removing high-frequency power between the switching unit and the member having the electrostatic capacitance. The measurement device according to claim 1 or 2, wherein the switching unit switches the connection of the electrodes to the member having electrostatic capacitance during the cleaning process, and The measurement unit measures a value corresponding to the amount of charge stored in the member having the electrostatic capacitance during the cleaning process. The measuring device according to claim 1 or 2, wherein the switching unit applies high-frequency power after switching the connection of the electrodes to the member having an electrostatic capacitance. The measuring device according to claim 1 or 2, which measures the self-bias voltage of the plasma based on the measured value corresponding to the electric charge. The measuring device according to claim 1 or 2, wherein the measuring unit has a probe provided in non-contact or contact with the surface of the member having electrostatic capacitance, and the member having electrostatic capacitance and the probe are arranged in a vacuum container Inside. A measurement method, which includes: switching process, which switches the connection of electrodes arranged in the electrostatic chuck in the plasma processing device; applying process, which applies high-frequency power to the above-mentioned electrostatic chuck; and measuring the process, the measurement is equivalent to using The value of the amount of charge stored in the member with electrostatic capacitance connected to the above-mentioned electrode by the above-mentioned switching process; components of capacitors; In the course of performing the above-mentioned substrate processing, the above-mentioned measurement process measures the above-mentioned value corresponding to the above-mentioned charge amount accumulated by the above-mentioned member having the electrostatic capacitance. The measuring method according to claim 8, wherein the switching process is to switch the connection of the electrodes between the DC power supply and the above-mentioned member with electrostatic capacitance. The measuring method according to claim 8 or 9, wherein after the switching process switches the connection of the electrode to the member having the electrostatic capacitance, the applying process applies high-frequency power. The measurement method according to claim 10, wherein the switching process switches the connection of the electrode to the above-mentioned member with electrostatic capacitance during the cleaning process, and the measurement process measures the equivalent of the above-mentioned capacitance during the cleaning process. The value of the amount of charge stored by a component of an electrostatic capacitance. The measurement method of Claim 8 or 9, which includes a determination process, the determination process refers to the memory with the previously measured value corresponding to the amount of charge and the relevant information indicating the value of the residual adsorption state of the electrostatic chuck The unit determines the residual adsorption state of the substrate based on the measured value corresponding to the amount of charge. Such as the determination method of claim item 12, wherein The determination process determines to perform cleaning or maintenance of the electrostatic chuck when the absolute value of the measured value corresponding to the electric charge exceeds a predetermined threshold with reference to the memory unit. A plasma processing device, which includes: a high-frequency power supply, which applies high-frequency power; a switching unit, which is an electrode arranged in an electrostatic chuck in the plasma processing device, and switches the connection of the electrode to which a DC voltage is applied; A member with electrostatic capacitance connected to the switching unit; and a measurement unit that measures a value corresponding to the amount of charge stored in the member with electrostatic capacitance; and during the process of performing substrate processing by plasma, the switching unit The unit switches the connection of the electrode to the member with electrostatic capacitance; and the measurement unit measures the value corresponding to the amount of charge accumulated on the member with electrostatic capacitance during the process of performing the substrate processing.

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