CN115516599A - System apparatus and method for using light irradiation to enhance electronic clamping of substrates - Google Patents

Abstract

A method may include: providing a substrate on a fixture; and emitting radiation from an illumination source to the substrate while the substrate is disposed on the fixture during substrate processing, wherein the radiation is characterized by radiant energy, wherein the At least a portion of the radiant energy is equal to or greater than 2.5 eV.

Description

System, apparatus and method for enhancing electronic clamping of a substrate using light irradiation

technical field

The present embodiments relate to substrate processing, and more particularly to electrostatic chucks for holding substrates.

Background technique

Substrate holders such as electrostatic chucks (also known as electrostatic chucks) are widely used in many manufacturing processes, including semiconductor fabrication, solar cell fabrication, and other component handling. Electrostatic clamping utilizes the principle of electrostatic induction in which electron charge is redistributed in an object due to the direct influence of nearby charges. For example, a positively charged object in the vicinity of an electrically neutral substrate will induce a negative charge on the surface of the substrate. This charge creates an attractive force between the object and the substrate. For the clamping of conductive and semiconductor substrates with relatively low bulk resistivities, charge redistribution is readily achieved by applying a voltage to electrodes embedded in the insulator adjacent to the conductive substrate. Accordingly, electrostatic chucks have been widely used to hold semiconductor substrates, such as silicon wafers, which have relatively low bulk resistivity.

One type of electrostatic clamp applies an alternating current (AC) voltage to create clamping, thereby enabling rapid clamping and unclamping of conductive substrates or low-resistivity semiconductor substrates. However, known direct current (DC) electrostatic clamps or AC electrostatic clamps are ineffective at clamping high resistivity semiconductor substrates or electrically insulating substrates.

Additionally, substrate charging issues can adversely affect substrate processing, especially for high resistance substrates, such as occurs during ion implantation. In addition to electrostatic grippers, non-electrostatic grippers (such as mechanical grippers) may contain conductive lift pins, ground pins, where when the substrate being gripped has a high electrical resistance, the Operation may be compromised. Additionally, in ion implantation apparatus, charge buildup on the substrate during implantation may require the use of charge compensation (eg, an electron flood gun) to counteract the charging of the substrate.

It is with regard to these and other considerations that the present disclosure is provided.

Contents of the invention

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be an aid in determining the scope of the claimed subject matter.

In one embodiment, a method may comprise: providing a substrate on a fixture; and emitting radiation from an illumination source to the substrate while the substrate is disposed on the fixture during substrate processing, wherein the radiation comprises radiation energy, wherein at least a portion of the radiation energy is equal to or greater than 2.5 eV.

In another embodiment, a method may include: providing a substrate on an electrostatic chuck; directing radiation from an illumination source to the substrate while the substrate is positioned on the electrostatic chuck; and An AC clamping voltage is applied to the electrostatic chuck while the radiation impinges on the substrate, wherein the radiation contains radiation energy equal to or greater than 2.5 eV.

In yet another embodiment, a method may include: providing a substrate on an electrostatic chuck; applying a clamping voltage to the electrostatic chuck to clamp the substrate; Simultaneously with the substrate, the substrate is processed. The method may further include removing the clamping voltage from the electrostatic chuck after the processing, and applying unclamping radiation from an illumination source while the substrate is disposed on the electrostatic chuck. Exposure to the substrate, wherein the unclamping radiation comprises unclamping radiation energy equal to or above a threshold for generating mobile charges in the substrate energy.

Description of drawings

FIG. 1 illustrates an electrostatic chuck arrangement according to an embodiment of the disclosure.

FIG. 1A illustrates a clamp device according to other embodiments of the present disclosure.

Figure 1B shows an example of electrostatic clamping.

FIG. 2 illustrates a side view of an electrostatic chuck device according to various embodiments of the disclosure.

3 illustrates a side view of another electrostatic chuck arrangement according to various embodiments of the present disclosure.

Figure 4 illustrates a side view of yet another electrostatic chuck arrangement according to various embodiments of the present disclosure.

Figure 5 illustrates a side view of yet another electrostatic chuck arrangement according to various embodiments of the present disclosure.

Figure 6 illustrates a side view of an additional electrostatic chuck arrangement according to various embodiments of the disclosure.

7 illustrates a side view of another electrostatic chuck arrangement according to various embodiments of the present disclosure.

7B and 7C illustrate the geometry of a scanned radiation beam according to two different embodiments.

FIG. 8 illustrates a side view of yet another electrostatic chuck arrangement according to various embodiments of the present disclosure.

Figure 9 shows a side view of an additional electrostatic chuck arrangement according to various embodiments of the present disclosure.

Figure 10 illustrates a side view of another electrostatic chuck arrangement according to various embodiments of the present disclosure.

11 illustrates a side view of another electrostatic chuck arrangement according to various embodiments of the present disclosure.

Figure 12 illustrates a side view of yet another electrostatic chuck arrangement according to various embodiments of the present disclosure.

Figure 13 illustrates a side view of a processing system according to various embodiments of the present disclosure.

Figure 14 shows the relationship between radiation wavelength and energy.

Figure 15 illustrates an exemplary control system for electrostatic clamping, according to some embodiments.

Figure 16 shows the relationship between charging time and resistivity for different substrate types.

Figure 17 shows an exemplary irradiance graph for a radiation source suitable for use in the electrostatic chuck arrangement of this embodiment.

Figure 18 shows the photocurrent generation as a function of the radiation energy of _SiO2 .

FIG. 19 shows another exemplary irradiance graph for a radiation source suitable for use in the electrostatic chuck arrangement of this embodiment.

Figure 20 shows an exemplary process flow.

Figure 21 shows another exemplary process flow.

Figure 22 shows yet another exemplary process flow.

Figure 23 shows an additional exemplary process flow.

Figure 24 shows another exemplary process flow.

Figure 25 illustrates an embodiment of a processing system.

detailed description

The present embodiment provides devices and techniques for increasing substrate clamping capability. In various embodiments, chucking apparatus and handling systems suitable for chucking various substrates, including high-resistivity substrates, are disclosed. Various embodiments employ radiation sources capable of producing visible light as well as shorter wavelength radiation, including wavelengths in the ultraviolet (UV) range and vacuum ultraviolet (VUV) range (<200 nm). Accordingly, various embodiments provide what may be referred to as an apparatus for light-assisted electronic clamping and release of various substrates, including irradiating the substrate with radiation before clamping, during clamping, and after clamping.

FIG. 1 illustrates an electrostatic chuck system 100 according to an embodiment of the disclosure. Electrostatic chuck system 100 may be deployed in any suitable environment in which substrates are clamped for any suitable purpose. In various embodiments, electrostatic chuck system 100 may be disposed in substrate chamber 102 to accommodate substrate 112 . In various non-limiting embodiments, substrate chamber 102 may represent a load chamber in which substrate 112 is loaded into the system, a transfer chamber in which substrate 112 is transferred between locations, or wherein substrate 112 is to be subjected to at least one Craft room for craft. Suitable process chambers include those for layer deposition on substrate 112, for etching of substrate 112, for heating of substrate 112, for ion implantation into substrate 112, or for other suitable processes. room.

As shown in FIG. 1 , the electrostatic clamp system 100 may include a clamp arrangement 104 including an electrostatic clamp assembly 114 . The electrostatic clamp assembly 114 may include known components of known electrostatic clamps, including cooling blocks, heaters, gas channels, electrodes, wiring, and the like. For clarity, only the general components of electrostatic clamp assembly 114 are shown. As shown in FIG. 1 , the electrostatic chuck assembly 114 may include an insulator portion 108 directly supporting a substrate 112 and an electrode assembly 110 that applies a voltage to the insulator portion 108 . In various embodiments, the electrode assembly 110 may include at least one electrode and be operable to apply a DC voltage or an AC voltage. In some embodiments, electrostatic chuck system 100 may be used as a known electrostatic chuck for clamping low-resistivity substrates.

As further shown in FIG. 1 , fixture arrangement 104 may also include an illumination system 106 configured to emit radiation (shown as radiation 120 ) at substrate 112 . According to various embodiments, radiation 120 may be characterized by a radiation energy equal to or higher than a threshold energy for generating mobile charges in substrate 112 . In this manner, irradiation system 106 may generate radiation 120 while applying a clamping voltage to electrostatic clamp assembly 114 . Thus, in operation and referring to FIG. 1B , when the substrate 112 is clamped by the electrostatic chuck assembly 114 , charges present within the substrate 112 can move in opposite polarity over the electrodes of the electrode assembly 110 to generate a high electric field. And produce a large clamping force.

It should be noted that the time required for such charge movement depends on the resistivity of the substrate 112, as shown in FIG. The range of resistivity and charge response time for different types of commonly used substrates is shown in FIG. 16 . Response times are shown for a substrate clamped using a clamping voltage without the application of the illumination system 106 . Substrates referred to as "conventional Si wafers" represent a range of resistivity for relatively low resistance silicon wafers (resistivities in the range of approximately 1 Ohm-cm to 1000 Ohm-cm are shown). In this example, the response time is approximately 1 μs to 100 μs. Also shown in FIG. 16 is the rise time and clamping period of the AC clamp. As shown, this rise time is consistent with the response time of a conventional silicon wafer. FIG. 16 also shows the response time of charges in a high bulk resistivity (HBR) silicon wafer (HBR Si wafer), an HBR silicon carbide wafer (HBR SiC) and a glass substrate. It should be noted that in the case of glass substrates, the volume resistivity of these other substrates extends over 10 seconds to 2 seconds to 108 seconds. These longer response times mean that charge cannot move within the substrates within the time period consistent with the applied AC voltage. Also, even with DC voltage applied, the response time is too slow for practical processing purposes, especially for HBR SiC and glass.

When the resistivity of the substrate 112 is too high, charges cannot move fast enough to establish a clamping force when a clamping voltage is applied by the electrostatic clamp assembly 114 . Compared to the timescales associated with clamping and handling the substrate 112, the charging time for an insulating substrate such as a glass wafer is virtually infinite, and the duration of the charging time can range from a few seconds to a few minutes. Magnitude. As such, without the use of the illumination system 106, substantially no substrate charge is generated in response to the applied clamping voltage, such that the clamping force is nearly zero.

Therefore, in the case of using the clamper device 104, substrates including HBR semiconductor wafers and glass can be clamped. In addition to solving the problem of clamping high-resistivity substrates, the clamping device 104 helps to solve another problem, that is, the generation of undesired charges on high-resistivity substrates, where removal of such charges can be caused, for example, by triboelectric And very difficult. The clamping device 104 additionally facilitates unclamping of the substrate by generating a mobile charge on the substrate 112 . The high resistivity of insulating materials arises from different factors. First, these materials often have very large electronic band gaps. For example, for silicon oxide such as _SiO2 , the bandgap is approximately 8eV. Unlike dopants in semiconductors, impurities in insulators also have much higher ionization energies. Therefore, the concentration of mobile charges in such a substrate is very low. Second, many common insulating materials are amorphous (eg, silica glass). The lack of a periodic crystal structure results in relatively low charge mobility. According to an embodiment of the present disclosure, the high resistivity can be enhanced significantly by transferring enough energy into the electrons of the high-resistivity material with the application of radiation 120 that the electrons enter a so-called extended state in the conduction band. The electrical conductivity of a substrate such as glass. For narrow bandgap semiconductors containing Si, low energy photons (such as those in infrared radiation) provide sufficient energy to overcome the bandgap. For wide bandgap semiconductor materials such as SiC, long-wave UV radiation (315nm to 400nm) may provide sufficient energy to overcome the bandgap and generate charge carriers. For such wavelength ranges, in various non-limiting embodiments, illumination system 106 may be implemented as a light source including laser diodes, light-emitting diodes (LEDs), arc lamps, or other sources.

According to additional embodiments, other types of radiation sources may be used with the illumination system 106 for substrates generally referred to as insulating substrates, such as glass substrates, as set forth in further detail below. In general, illumination system 106 will be arranged to provide radiation 120 with sufficient energy to generate mobile charges for the type of substrate being used as substrate 112 . However, in various non-limiting embodiments, illumination system 106 can be configured to hold at least the following substrate types: 1) conventional silicon wafers: resistivity <1000 ohm-cm; 2) high resistivity silicon and/or on insulator Silicon-on-insulator (SOI) wafers: resistivity 1000 ohm-cm to 100,000 ohm-cm; 3) silicon carbide wafers: usable resistivity up to 1E9 ohm-cm; and 4) glass: resistivity >1E12 ohm - cm; 5) Silicon on glass.

According to various embodiments of the present disclosure, the illumination system 106 is arranged to provide illumination to the major surfaces of the substrate 112 , including the front surface 112A on the front side or the back surface 112B on the back side. According to various embodiments, the radiation 120 may be provided directly in a line-of-sight manner, may be provided by reflection, may be by blanket irradiation of the substrate, by scanning the substrate, by scanning the irradiation source or the described A combination of methods to provide radiation 120. Ideally high intensity uniform light illumination over the entire substrate is useful. Due to constraints on the configuration of the light source and the electrostatic chuck arrangement, certain embodiments provide novel configurations to maximize the efficiency of light generation in the substrate. In the following embodiments shown in FIGS. 2 to 8 , a different electrostatic chuck system is shown, in which a substrate table 202 is shown, which may include an electrostatic chuck as generally explained above with respect to FIG. 1 .

Turning to FIG. 1A , a clamp apparatus 150 is shown in accordance with additional embodiments of the present disclosure. In such a case, clamping apparatus 150 includes mechanical clamps 154 (and optionally stand offs 156) to hold substrate 112 using any suitable mechanical assembly. The fixture arrangement 150 includes the illumination system 106 described above. In operation, while substrate 112 is held by mechanical gripper 154, radiation 120 may be directed at substrate 112 to increase mobile charge in substrate 112 and to aid in handling of the substrate, such as between substrate 112 and lift pins. Either provide better conductivity between ground pins (not shown separately) or by reducing surface charging of the substrate 112 .

FIG. 2 illustrates a side view of an electrostatic chuck system 200 according to various embodiments of the disclosure. In this embodiment, illumination system 201 is positioned to emit radiation 208 onto the front surface of substrate 112 . While in some embodiments the substrate table 202 may be stationary, in other embodiments the substrate table 202 may include a scanning assembly (such as a known scanning assembly (not shown)) to scan along at least one direction. The substrate 112 is scanned. Also, in some embodiments, radiation 208 may be provided as a fixed beam arranged to cover the entire substrate. In some embodiments in which the substrate table 202 is arranged to scan the substrate, for example along the Y-axis of the illustrated Cartesian coordinate system, the radiation 208 may be provided in a manner covering the entire scan range of the substrate 112. , as shown in Figure 2. For example, illumination system 201 may include a component referred to as illumination source 204, including components that generate radiation 208 at a suitable energy to generate photocarriers in substrate 112, where examples of different illumination sources are detailed below. elaborate. Illumination source 204 may generate radiation as a beam having a particular size. In some embodiments, the beam emitted by illumination source 204 may be large enough or expandable to become large enough to cover substrate 112 .

In other embodiments, illumination system 201 may further include an optical system 206 disposed between illumination source 204 and substrate 112 to expand the radiation beam received from illumination source 204 and to expand the radiation beam used to generate radiation 208 to The entire substrate 112 is covered. An example of an optical system suitable for optical system 206 is a set of refractive optics, such as optical lenses. In this and the following examples, "optical system" will provide the ability to handle radiation in the UV range, which means that refractive optics will mean optics for refracting UV radiation, and mirror optics will Suitable for reflecting UV radiation.

FIG. 3 illustrates a side view of an electrostatic clamp system 220 according to various embodiments of the disclosure. In this embodiment, illumination system 211 is positioned differently to emit radiation 212 onto the front surface of substrate 112 . While in some embodiments the substrate table 202 may be stationary, in other embodiments the substrate table 202 may include a scanning assembly (such as a known scanning assembly (not shown)) to scan along at least one direction to scan the substrate 112 . Also, in some embodiments, radiation 212 may be provided as a fixed beam arranged to cover the entire substrate. In some embodiments in which the substrate table 202 is arranged to scan the substrate, for example along the Y-axis of the Cartesian coordinate system shown, the radiation 212 may be provided in a manner covering the entire scan range of the substrate 112, as in FIG. shown. For example, illumination system 211 may include illumination source 204 discussed above with respect to FIG. 2 . Illumination source 204 may generate radiation as a beam having a particular size. In such a configuration, the illumination source 204 may emit radiation as a beam that does not initially exit toward the substrate 112 . The illumination system 211 may also include an optical system 210 arranged to reflect the beam generated by the illumination source 204 and to emit the reflected beam as radiation 212 to the substrate 112 . Optical system 210 may include optical mirrors, and in some embodiments, optical mirrors may be arranged as expanding mirrors to expand the radiation beam received from illumination source 204, reflect and expand the radiation beam used to generate radiation 212 to cover the entire Substrate 112. In additional embodiments, the illumination system may comprise a combination of refractive optics and mirror optics. The selection of optics for illumination can be guided by consideration of the spacing and placement of elements and the efficiency of producing illumination covering the substrate 112 .

FIG. 4 illustrates a side view of another electrostatic clamp system 250 according to various embodiments of the present disclosure. In this example, electrostatic chuck system 250 may include substrate table 202 and illumination source 204 as described generally above. Electrostatic chuck system 250 may additionally include an illumination system 251 having an optical system 252 that differs from the embodiment shown in FIG. 2 in that optical system 252 includes components that provide scanning capabilities for radiation beams received from illumination source 204 . Scanning capabilities may be provided by, for example, motorized components. According to various embodiments, radiation 254 may be provided as a beam expanded from an initial beam size.

According to various embodiments of the present disclosure, optical system 252 provides beam scanning of radiation 254 . In some embodiments, in configurations in which the substrate 112 is scanned, the optical system 252 may also scan the radiation to follow the scan of the substrate 112 . For example, illumination source 204 and optical system 252 may include refractive optics that produce radiation 254 as a beam having a width that covers substrate 112 .

The optical system 252 may further be configured with a lens drive mechanism arranged to move the optical lens by rotation, translation or rotation and translation. For example, optical system 252 may be further configured with a scanning assembly wherein radiation 254 is scanned in the same direction at the same rate as substrate 112 is scanned along the Y-axis at a rate of 10 cm per minute such that radiation 254 is In any case the substrate 112 is covered. In this way, even when substrate 112 is scanned, the width of radiation 254 exiting substrate 112 need not be significantly greater than the substrate width, thus protecting other components in the remainder of the chamber containing substrate 112 .

In other embodiments, radiation 254 may be provided as a relatively narrow beam compared to the width of substrate 112 (eg, a laser beam or a highly collimated incoherent beam). This embodiment is represented by radiation beam 254A, which is shown to have a much smaller width relative to the width of substrate 112 at least along the Y direction. In this embodiment, the optical system 252 may be provided with components that rapidly scan the radiation beam 254A along, eg, the Y direction, to cover the entire substrate 112 in such a way as to provide an average uniform irradiance. In embodiments in which the substrate 112 remains stationary, the optical system 252 can thus only scan the radiation beam 254A in a rapid manner to create a radiation umbrella covering the stationary substrate.

FIG. 5 illustrates a side view of another electrostatic clamp system 260 according to various embodiments of the present disclosure. In this example, electrostatic chuck system 260 may include substrate table 202 and illumination source 204 as described generally above. Electrostatic chuck system 260 may additionally include an illumination system 261 having an optical system 262 that differs from the embodiment shown in FIG. 3 in that optical system 262 includes components that provide scanning capabilities for radiation beams received from illumination source 204 . Scanning capabilities may be provided by, for example, motorized components. According to various embodiments, radiation 264 may be provided as a beam expanded from an initial beam size.

According to various embodiments of the present disclosure, optical system 262 provides beam scanning of radiation 264 . In some embodiments, in configurations in which the substrate 112 is scanned, the optical system 262 may also scan the radiation to follow the scan of the substrate 112 . For example, illumination source 204 and optical system 262 may include reflective optics, such as UV mirrors, that produce radiation 264 as a beam having a width that covers substrate 112 . Optical system 262 may further be configured with a scanning assembly wherein when substrate 112 is scanned at a given rate along the Y-axis, radiation 264 is scanned in the same direction at the same rate so that radiation 264 in any case covers Substrate 112. In this way, even when substrate 112 is scanned, the width of radiation 264 exiting substrate 112 need not be significantly greater than the substrate width, thus protecting other components in the remainder of the chamber containing substrate 112 .

In other embodiments, the radiation from the illuminating beam may be provided as a relatively narrow beam compared to the width of the substrate 112 (eg, a laser beam or a highly collimated incoherent beam). This embodiment is represented by electrostatic clamping system 270 shown in FIG. 6 . The substrate table 202 may be generally configured as in the previous embodiments. In this embodiment, the illumination system 271 includes an illumination source 272 that produces a narrow beam, which is shown to have a much smaller width relative to the width of the substrate 112 at least along the Y direction. The illumination source 272 may be a laser source or a collimated incoherent light source. In this embodiment, optical system 274 may be provided with a refractive assembly to receive and deliver the beam emitted from illumination source 272 as a narrow beam, shown as radiation beam 276, along the The radiation beam 276 is scanned, for example in the Y direction, to cover the entire substrate 112 .

In embodiments where the substrate 112 remains stationary, the optical system 274 may thus only scan the radiation beam 276 in a rapid manner to create a radiation umbrella 278 covering the stationary substrate. In other embodiments in which the substrate 112 is also scanned, for example along the Y-axis, the optical system 274 may include both rapidly scanning the radiation beam 276 across the substrate 112 and aligning the average position of the radiation beam 276 with the substrate's Move components that are slowly offset synchronously. In this manner, the radiation 264 produces a radiation umbrella 278 whose dimension along the Y-axis closely corresponds or matches the dimension of the substrate along the Y-axis and which is positioned such that the radiation umbrella 278 Overlying the entire substrate 112 or desired portions of the substrate 112 while not extending beyond the substrate 112 . More generally, the electrostatic clamping system 270 may include a synchronization component to synchronize the movement of the optical lens with the movement of the substrate table scanner (shown by double arrows) so that the radiation beam remains Aligned with the front side of the substrate 112 . Another embodiment in which the radiation beam is provided as a scanned narrow beam is shown in FIG. 7 . This embodiment is represented by an electrostatic clamping system 280 in which the substrate table 202 may be configured generally as in the previous embodiments. In this embodiment, illumination system 281 may include illumination source 272 that produces a narrow beam, as described above with respect to FIG. 6 . In this embodiment, optical system 284 may be provided with components that reflect the beam emitted from illumination source 272 as a narrow beam (shown as radiation beam 286) and to provide an average uniform irradiance. The radiation beam 286 is scanned along, for example, the Y direction in such a manner as to cover the entire substrate 112 .

In embodiments where the substrate 112 remains stationary, the optical system 284 may thus simply scan the radiation beam 286 in a rapid fashion (eg, rapidly moving or rotating a mirror) to create a radiation umbrella 288 covering the stationary substrate. In other embodiments in which the substrate 112 is also scanned, for example along the Y-axis, the optical system 284 may include both rapidly scanning the radiation beam 286 across the substrate 112 and synchronizing the average position of the radiation beam 286 with the movement of the substrate. slowly shifting components. In this way, the radiation 264 produces a radiation umbrella 288 whose dimension along the Y-axis closely corresponds or matches the dimension of the substrate along the Y-axis and which is positioned such that the radiation umbrella 288 Overlying the entire substrate 112 or desired portions of the substrate 112 while not extending beyond the substrate 112 .

In various embodiments in which the optical system provides radiation to the substrate 112 as a scanned narrow radiation beam, the scanned radiation beam may be in the plane of the substrate 112 (this means in the X-Y plane, as shown ) are provided as spot beams or ribbon beams. FIG. 7B shows an embodiment in which radiation beam 276 or radiation beam 286 is provided as a ribbon beam elongated along the X-axis. The ribbon beam may have a length dimension comparable to the length of substrate 112 along the X-axis, and thus may not be scanned along the X-axis, but only along the Y-axis, to produce radiation umbrella 278 or radiation umbrella 288 . FIG. 7C shows an embodiment in which the radiation beam 276 or the radiation beam 286 is provided as a spot beam which has a relatively small size compared to the width of the substrate 112 along the X-axis and thus can be Both the X-axis and the Y-axis are scanned to produce either the radiation umbrella 278 or the radiation umbrella 288 .

In additional embodiments, the electrostatic chuck system may include optics that combine a mirror assembly with a refraction assembly to exit the radiation beam to the substrate.

FIG. 8 illustrates a side view of yet another electrostatic chuck arrangement according to various embodiments of the present disclosure. In this embodiment, an electrostatic chuck system 290 comprising the previously explained substrate table is shown. Unlike the previously set forth embodiments, electrostatic chuck system 290 includes an illumination system 291 that includes multiple illumination sources. In the embodiment shown in FIG. 8, two different illumination sources are included (shown as illumination source 204A and illumination source 204A), where each illumination source can be configured similarly to illumination source 204 set forth above. However, in other embodiments, more than two illumination sources may be employed. In the configuration shown in FIG. 8 , illumination system 291 includes optical system 292 arranged to emit two beams of radiation onto substrate 112 using a mirror configuration of mirror system 292A and mirror system 292B for illumination by illumination source 204A. and illumination source 204B and are reflected by radiation shown as radiation 294A and radiation 294B, respectively. In a different variation, the optical system 292 may operate similarly to the previous embodiments shown, for example, in FIGS. Reflects to the substrate and provides either a slow scan or a fast scan of the radiation beam as described above. The configuration shown in Figure 8 provides the advantage that the substrate 112 can be illuminated more uniformly than with a single radiation beam. In other embodiments, multiple illumination sources may be coupled to corresponding multiple refractive optics (similar to the configurations shown in FIGS. A plurality of illumination sources is coupled to the combination of at least one refractive optic and at least one mirror optic. Such an embodiment may be useful for housing an optical system within a given processing apparatus where the configuration of other components including, for example, the substrate table, and processing components may impose constraints on the location of the other components.

One disadvantage of directing radiation onto the front surface of the substrate is that photocarriers tend to be generated near the front surface while clamping occurs on the back surface of the substrate. For high-mobility materials, the generation of photogenerated charge carriers near the front surface is not a problem for clamping the substrate since the carriers can quickly traverse the substrate, but for low-mobility materials such as glass), it may take too long for the charge carriers to reach the backside of the wafer. In a further embodiment of the present disclosure, the illumination system may be arranged to emit radiation onto the backside of the substrate.

Figure 9 shows a side view of an additional electrostatic chuck arrangement according to various embodiments of the present disclosure. In this embodiment, the electrostatic clamping system 300 is arranged with an illumination system 301 , wherein at least a part of the illumination system 301 is embedded within a substrate table 302 . It should be noted that the substrate table 302 may be configured similarly to the previous embodiments of the substrate table 202 and may include an electrostatic chuck as well as a scanning assembly for scanning the substrate table 302 . Illumination system 301 may include a plurality of illumination sources (shown as illumination source 304, illumination source 306, and illumination source 308) distributed in various locations within the X-Y plane. In general, the different illumination sources can be distributed across the substrate table 302 in a one-dimensional array or in a two-dimensional array, wherein the substrate table includes openings facing the substrate 112 to deliver radiation directly to the substrate 112 without obstruction. The rear side of the rear surface 112B of the substrate 112 is included. In other words, the gap between the substrate table 302 and the substrate 112 can act as a hollow light guide, allowing radiation, such as UV light, to pass beyond the point of entry.

Although the embodiment shown in FIG. 9 shows an illumination system with multiple illumination sources, in other embodiments a single illumination source may be used. Figure 10 illustrates a side view of another electrostatic chuck arrangement according to various embodiments of the present disclosure. In this embodiment, the electrostatic clamping system 310 is arranged with an illumination system 311 , wherein a part of the illumination system 311 is embedded within the substrate table 312 and a part is located outside the substrate table 312 . It should be noted that the substrate table 312 may be configured similarly to the previous embodiments of the substrate table 202 and may include an electrostatic chuck as well as a scanning assembly for scanning the substrate table 312 . The illumination system 311 includes an illumination source 314, which may represent only one illumination source. The illumination source 314 is coupled to a plurality of light guides (optical guides) extending through the substrate table 312 such that radiation can be provided directly to the back surface 112B of the substrate 112 . In general, the different light guides can be distributed in a one-dimensional array or a two-dimensional array across the substrate table 302, wherein the substrate table includes a plurality of openings 319 facing the substrate 112 to direct the radiation without obstruction. to the rear surface 112B of the substrate 112 . For simplicity, these light guides are shown as light guide 320 , light guide 316 and light guide 318 . As shown, the plurality of light guides are connected at distal ends to an illumination source 314 and have proximal ends extending through the plurality of openings 319 , respectively.

The foregoing embodiments shown in Figures 9 and 10 thus provide an efficient way of coupling high energy radiation, such as UV radiation, directly to the substrate in a uniform manner.

11 illustrates a side view of another electrostatic chuck arrangement according to various embodiments of the present disclosure. In this embodiment, the electrostatic chuck system 350 includes a substrate table 352 having an illumination system 351 embedded within the substrate table 352 . It should be noted that the substrate table 352 may be configured similarly to the previous embodiments of the substrate table 202 and may include an electrostatic chuck as well as a scanning assembly for scanning the substrate table 352 . Illumination system 351 includes an illumination source 354 embedded in a substrate table 352 and a set of coupling optics (shown as coupling optics 356 ) to receive radiation from illumination source 354 and output it in a direction that couples radiation 358 Radiation 358 is directed to the rear surface 112B of the substrate 112 . As shown in FIG. 11, the gap between the substrate table 352 and the substrate 112 can act as a hollow light guide.

Although the foregoing embodiments shown in FIGS. 2-11 have been described with respect to electrostatic clamps, in other embodiments, the illumination system shown in FIGS. 2-11 may be implemented using a mechanical clamp.

Figure 12 illustrates a side view of yet another electrostatic chuck arrangement according to various embodiments of the present disclosure. In this embodiment, the electrostatic chuck system 360 includes an illumination system 361 formed from an illumination source and an electrode assembly 368 disposed within a substrate table 362, the illumination system 361 being arranged to direct radiation 366 toward the backside of the substrate 112 ( See rear surface 112B) ejection. It should be noted that the substrate table 362 may be configured to include an electrostatic chuck as well as a scanning assembly for scanning the substrate table 362 . Unlike known electrostatic clamps, the substrate table assembly, including the electrostatic clamp assembly, may be formed from a material that is transparent to radiation 366 . For example, the dielectric materials used for the stage components and electrostatic clamps, including the transparent platen body, and the cooling gas emitted into the substrate table 362 may be made of a material that is transparent to the UV light used to form the radiation 366 .

As shown in FIG. 12 , radiation 366 may form a broad beam of radiation covering most or all of substrate 112 . In this embodiment, the electrostatic chuck portion (not separately shown) of the substrate table 362 includes an electrode assembly 368 arranged as one of a metal screen or mesh. or a plurality of electrodes, wherein the transparency of the metal mesh is high. In this way, the metal mesh can act as a uniform electrode system for electrostatic clamping while providing high transparency to UV radiation or other high energy radiation emitted by the illumination source 364 .

In additional embodiments of the present disclosure, electrostatic clamping systems, including those disclosed with respect to FIGS. 1-12 , or variations thereof, may be deployed in substrate processing systems to process substrates. In some embodiments, an electrostatic clamping system is provided in the substrate processing chamber so that the substrate can be held while being processed. Figure 13 shows a side view of one such processing system according to various embodiments of the present disclosure. As shown, processing system 380 includes a process chamber 382 that may house various components of an electrostatic chucking system, including a substrate table 385 and an illumination system 391 . In the configuration shown, the illumination system 391 includes reflective optics for front side illumination, while in other embodiments the illumination system may be based on refractive optics for front side illumination or may be based on back side illumination, where each This configuration has been described in detail with respect to Figures 1 to 12. In this example, the illumination source 388 is disposed outside the substrate table 385 . In different embodiments, the illumination source 388 may be disposed within the process chamber 382 , partially within the process chamber 382 , or disposed outside of the process chamber 382 . In the example shown in FIG. 12 , illumination source 388 emits a beam to UV mirror 392 , which reflects the beam to emit radiation 396 onto substrate 112 . The geometrical configuration of illumination source 388, UV mirror 392, and substrate 112 is arranged to ensure that the source UV beam generated by illumination source 388 is properly expanded to cover the substrate. Similar to some of the previous embodiments, a mirror drive mechanism may be incorporated and arranged to move an optical mirror, such as UV mirror 392, by rotation, translation, or rotation and translation. As shown in the embodiment of FIG. 13 , scan motor 390 is mechanically coupled to UV mirror 392 to scan UV mirror 392 in the manner described above for movement or scanning of substrate 112 . In some embodiments, a control system 398 coupled to the UV mirror 392 and the substrate table 394 is used to control the scanning of the UV mirror 392 and the substrate table 394 such that the expanded beam (radiation 396) emits most or all of the radiation 396 The means intercepted by the substrate 112 follow the movement of the substrate. Accordingly, control system 398 may generate scan control and position sensing signals for controlling substrate table 394 and optical beam scan control and position sensing signals for controlling scan motor 390 and UV mirror 392 .

UV photons of radiation 396 are provided to generate sufficient mobile charges such that the substrate can be adequately gripped by an electrostatic clamp (not shown separately) within substrate table 394 even with a high bandgap above 2.5 eV.

The processing system 380 also includes a beam generating assembly 384 to emit an ion beam 386 into the process chamber 382 . Ion beam 386 may implant ions into substrate 112 while substrate 112 is held in place by the action of an electrostatic chuck system including illumination system 391 and an electrostatic chuck located within substrate table 394 . Unlike known ion implantation systems, the processing system 380 can be conveniently implanted into high resistance or insulating substrates where the substrate is still electrostatically clamped to the substrate table.

Although in the embodiment shown in FIG. 12 beam generation assembly 384 may represent a series of beam line assemblies for delivering an ion beam to a substrate, in other embodiments, the components of the preceding embodiments that include an electrostatic clamping system The process system can be used to process the substrate for any suitable process (including film deposition, etching, heating, etc.).

In various embodiments of the present disclosure, the ability of the UV irradiation system or high energy irradiation system to assist in the electrostatic chucking of high resistivity substrates may be enhanced using the control system 398 or similar control systems. It should be noted that, depending on the configuration of the process chamber and the capabilities of the irradiation source, the irradiation of the substrate may need to be synchronized with the scanning of the substrate and the electronic clamping of the substrate to improve the effectiveness of the irradiation. As previously described, when a scanning UV beam is used to irradiate a substrate, the control system 398 may synchronize the UV beam scanning with the scanning of the substrate table. FIG. 15 illustrates an exemplary control system arrangement 400 for electrostatic clamping, according to some embodiments. In this example, a controller 398A is coupled to various components of the electrostatic clamping system. For simplicity, illumination system 402 is shown that emits radiation 404 onto the front side of substrate 112 without using any optical components. It should be noted that illumination system 402 may include the components described above for scanning radiation 404 . An electrostatic clamp 406 is disposed in a substrate table 408 and includes an AC electrode system 410 . A motor 412 is coupled to the substrate table to scan the substrate table 408 . Additionally, an AC voltage source 414 is coupled to the AC electrode system 410 to supply a voltage signal (including an AC voltage) to the electrodes of the AC electrode system 410 . Controller 398A may be coupled to illumination system 402, motor 412, and AC voltage source 414 to synchronize the actions of these components. For example, the timing of irradiating the substrate 112 can be synchronized with the electrical excitation of the substrate using the controller 398A. In some embodiments, the controller 398A can be used to source the AC voltage source 414 to provide a given voltage waveform whose amplitude, AC frequency, and rise time are arranged to ensure that the AC voltage can be generated within the same half cycle of the AC voltage. enough photocarriers. The details of a given voltage waveform may be based on the available UV intensity produced by the illumination system 402 .

In certain embodiments, the controller 398A may monitor the current clamp signal of the electrostatic chuck 406 to determine the charging status of the substrate 112 . In some embodiments, the clamping current signal may also be used to sense the wafer type before starting substrate clamping.

example

source of radiation

According to some embodiments, illumination system 106 or any of the other aforementioned illumination sources may be a visible light source. These embodiments of visible light sources would be particularly suitable for use in low-bandgap semiconductor substrates (eg, silicon, III-V compound semiconductors, II-VI compound semiconductors) where the bandgap may be below approximately 2.5 eV.

According to other embodiments, the illumination system 106 or any of the other aforementioned illumination sources may be a long-wavelength UV source, producing radiation in the wavelength range of 120nm to 240nm (this means an energy range of approximately 3eV to 4eV). radiation. These embodiments of the UV radiation source will be particularly suitable for use with wide bandgap semiconductor substrates such as silicon carbide (SiC).

According to a further embodiment, the illumination system 106 or any of the other aforementioned illumination sources may be a VUV source, producing a wavelength range between 120nm to 240nm or below 120nm (this means approximately 5eV to 10eV or above 10eV radiation in the energy range). These embodiments of the VUV radiation source will be particularly suitable for use with insulator substrates such as glass.

In some examples, any of the foregoing illumination sources can be a multi-wavelength source, wherein a broad range of wavelengths can be obtained from a single illumination source or from a plurality of different illumination sources. The same electrostatic fixture system can therefore employ light sources with multiple wavelengths, where the shortest wavelength source is selected for substrates with the highest energy bandgap, and longer wavelength and Source of higher radiant flux to achieve higher conductivity.

While in some instances lasers may be employed to generate single-wavelength radiation, in other instances incoherent sources may be used to generate radiation characterized by a continuous or discrete wavelength spectrum, where power is highly concentrated in a small number of resonant lines ( frequency) around.

In certain examples, filters can be used to further tailor the output wavelength spectrum from the illumination source. For example, for some substrate processing applications, UV-sensitive adhesives are used to bond silicon wafers to glass substrates. If the longer wavelengths that are transparent to the glass are filtered out from the radiation emitted by the radiation source using a filter placed between the radiation source and the substrate, then the shorter wavelength portion of the radiation can then be used in the event of incomplete penetration through the glass and damage to the adhesive. In the case of a mixture, photocarriers are generated in the glass.

Non-limiting examples of suitable laser sources include diode lasers producing wavelengths down to 191 nm, other solid state lasers, excimer lasers (eg ArF, KrF, F2), continuous wave lasers, pulsed lasers, and the like.

Examples of suitable incoherent sources include deuterium lamps, electrodeless lamps (including line sources or continuous wavelength sources). An example of a deuterium lamp source output spectrum is shown in Figure 19, with some details omitted for clarity. The output of such a source may be suitable for generating charge carriers in insulators with band gaps higher than around 6eV. Some examples of commercially available resonant line sources are shown in Table I, including the type of radiation source and the wavelength of radiation. Some examples of commercially available continuum sources are shown in Table II.

(nm) hydrogen 121.6 krypton 116.5 123.6 xenon 129.6 147.0 HG 184.9 253.7 iodine some

Table I

Table II

In one example, a VUV argon continuum source was used as the irradiation source to aid in the electrostatic clamping of glass or fused silica substrates. Fused silica has a bandgap of approximately 8eV, which requires a light source with a wavelength <150nm to generate photocarriers. Figure 18 shows the photocurrent produced by a glass substrate as a function of photon energy. As shown in the figure, no photocurrent is generated when it is lower than 8eV, and the photon energy gradually increases until it reaches 9eV. Above this energy, the photocurrent increases rapidly, and the photocurrent reaches saturation at or above 10eV. A reference dashed line at 9.5 eV is shown. In one embodiment, an ArCM-LHP high power argon continuum source may be used, resulting in an output spectrum as shown in FIG. 17 . The output spectrum is idealized to omit some small details while showing the general characteristics of the argon emission spectrum. As shown, the peak wavelengths are in the range between 116nm and 140nm, with most of the integrated intensity of the broad emission spectrum at wavelengths below approximately 133nm (indicated by the dashed line), corresponding to 9.5eV or greater than 9.5eV energy. This energy range matches that in which the photocurrent in the glass produces significant energy, as shown in FIG. 18 . Such seeds are commercially available in a relatively compact footprint to easily fit into a common processing chamber.

UV mirror

_In one example, an aluminum mirror with MgF2 coating can be used as a UV mirror to generate high reflectivity in the UV range as well as in the VUV range. Commercially available mirrors based on this material can produce reflectivity above about 75% in the wavelength range from at least 300nm down to 120nm, providing high reflectivity of the initial UV beam. Such high reflectivity will facilitate beam expansion and steering using well known methods for visible light mirror systems.

Electrostatic clamping is achieved by AC clamping the glass substrate using an argon arc lamp :

As described above, when attempting to clamp an insulating substrate (dielectric substrate) in the absence of photocarriers such as those generated according to the preceding embodiments, the clamp electrodes of the electrostatic clamp (electronic clamp) are over the entire An electric field is established in the dielectric.

Using the frontside illumination disclosed above, charge carriers are generated at the top of the insulating substrate. Under the influence of the applied electric field, the carriers move towards the rear surface of the substrate (see FIG. 1B ). The result of this process is an intensified electric field in the gap between the substrate and the electronics fixture. In the absence of generation of charge carriers, the electric field in the gap is approximately V/w, where V is the voltage difference between the electrodes and w is the spacing between the electrodes. If the surface charge layer is fully developed as shown in Figure IB, the electric field in the gap is approximately V/d, where d is the gap between the substrate and the electrode and the dielectric thickness of the dielectric material. This thickness is usually much smaller than the electrode spacing. A 10- to 100-fold electric field enhancement corresponding to a 100- to 10,000-fold enhancement of the clamping force can easily be achieved. Therefore, a useful goal is to establish a sufficiently high surface charge density in a sufficiently short time to realize the potential benefit of increased clamping force. For example, to achieve effective AC clamping, the time for charge accumulation needs to be much shorter than the period of the applied AC voltage.

对应的输出角度2θ＝45°。对于不同的输出角度及光子通量，如所属领域中的技术人员所理解的，可定量地调整计算。也可使用UV镜将反射损失引入到所述灯输出的束。此外，可假设扩展的束面积稍大于衬底面积，所述情形也会降低束通量的利用率。假设镜损失与衬底外束损失一同导致可用束通量的50％损失。此假设指示衬底上的1.45×10¹⁶光子/秒的光子通量或者300mm晶片的Φ＝2×10¹³光子/秒/cm²。先前已通过实验及数值方法对光载流子在二氧化硅中的传输进行广泛研究。光传导是复杂的过程。传导电流受以下因素的影响：光吸收率、量子良率、移动载流子的寿命(此寿命取决于重组速率及陷获速率且对于电子及空穴来说可非常不同)、电子及空穴迁移率(此迁移率可能相差许多数量级)、绝缘体中的空间电荷累积以及跨越衬底与电子夹具之间的界面的电荷转移。因此，基于基本材料性质估测电流并非是适当可靠的，且相反，本文中的电流计算是基于实验测量的光电流。在一个特定实例中，电子夹具被设计成使得在玻璃衬底中实现5kV/mm的电场强度。已知研究的结果表明，在以上电场值下，在5×10¹¹光子/秒/cm²的通量下将产生7.6×10^-9A/cm²的传导电流密度。在此实例中使用较高的灯强度(2×10¹³光子/秒/cm²)，将电流密度估测为J＝3×10^-7A/cm²。在目标夹持压力为50torr的实验条件下，产生此种夹持力所需的电荷密度由下式给出：In the calculations that follow, it is assumed that a known ArCM-LHP lamp is used as an illumination source producing the radiation spectrum shown in Fig. 18, where the lamp can transfer electron energy 6× above the _SiO2 bandgap of about 8 eV 10 ¹⁶ photons/sec/steradian and with fixed angle

The corresponding output angle 2θ=45°. The calculations can be adjusted quantitatively for different output angles and photon fluxes, as understood by those skilled in the art. UV mirrors can also be used to introduce reflection losses to the beam output by the lamp. Furthermore, it can be assumed that the expanded beam area is slightly larger than the substrate area, which also reduces the utilization of the beam flux. It is assumed that mirror losses together with beam losses outside the substrate result in a 50% loss of available beam flux. This assumption indicates a photon flux of 1.45×10 ¹⁶ photons/second on the substrate or Φ=2×10 ¹³ photons/second/cm ² for a 300 mm wafer. The transport of photocarriers in silica has been extensively studied before, both experimentally and numerically. Light transmission is a complex process. The conduction current is influenced by: light absorption rate, quantum yield, lifetime of mobile carriers (this lifetime depends on recombination rate and trapping rate and can be very different for electrons and holes), electron and hole Mobility (which can vary by many orders of magnitude), space charge accumulation in the insulator, and charge transfer across the interface between the substrate and the electron fixture. Therefore, estimating the current based on fundamental material properties is not reasonably reliable, and instead the current calculations herein are based on experimentally measured photocurrents. In one particular example, the electronic fixture was designed such that an electric field strength of 5 kV/mm was achieved in the glass substrate. The results of known studies show that at the above electric field values, a conduction current density of 7.6×10 ⁻⁹ A/cm ² will be generated at a flux of 5×10 ¹¹ photons/second/cm ² . Using a higher lamp intensity ( ^2x1013 photons/sec/ ^cm2 ) in this example, the current density was estimated to be J = ^3x10-7 A/ ^cm2 . Under experimental conditions with a target clamping pressure of 50 torr, the charge density required to generate such a clamping force is given by:

Therefore, the characteristic charging time in this example is given by:

This time is fast enough for low frequency AC excitation, for example with a frequency of 1 Hz to 2 Hz or a period of 500 ms to 1 s. It should be noted that this estimate of the characteristic charge time is an estimate of the order of magnitude of the response time using actual electronic fixture electronics designs and commercially available VUV sources. The evaluation shows the feasibility of using the method described above to achieve practical AC clamping of insulating glass wafers. In other examples, charging time can be reduced to less than 0.1 seconds by using multiple light sources to increase VUV intensity and optimizing electronic fixture electronic design and increasing electric field.

Clamping of high resistivity Si wafers and SiC wafers

As mentioned above, commercially available HBR silicon wafers can show resistivities in the range of 100 kOhm-cm to be usable. For SiC substrates, a resistivity of 10 ⁹ Ohm-cm has been reported. However, a practical system for generating _{photocarriers} in commonly used _HBR semiconductor substrates can use a UV light source, where the main energy output is at The energy output of the substrate is slightly longer wavelength (>250nm). In addition, compared with glass, crystalline semiconductors (such as Si and SiC) have high electron and hole mobility and fewer defects that cause trapping, and the structure also helps to reduce the transfer of photocarriers under the electric field. over time. Therefore, given the above experimentally based results indicating a charging time of about 0.1 seconds for SiO, charging times significantly less than this can be achieved for HBR Si substrates and HBR SiC substrates, using the exemplary irradiation disclosed herein Source and fixture device to achieve.

While the foregoing embodiments have focused on the use of high energy irradiation to achieve clamping enhancement of high-resistivity substrates, de-chucking can also be enhanced according to additional embodiments. In other words, when a semiconductor substrate or an insulating substrate is clamped using an electrostatic clamp, the clamping voltage can be removed in a case where the substrate is to be unclamped. According to the embodiments disclosed above, to enhance de-chucking of the substrate, photocarriers may be generated by exposure to an illumination source. In this way, the rate of decay of the previously established electric field and the removal of certain charges, such as neutralizing residual static charges, can be accelerated. Such strengthening is applicable to "conventional" semiconductor substrates with relatively low bandgaps (eg in the visible range) as well as to HBR semiconductor and insulator substrates.

FIG. 20 illustrates an exemplary process flow 500 . At block 502, a substrate is provided on an electrostatic chuck assembly. In some embodiments, the substrate may be a HBR semiconductor substrate or an insulating substrate. At block 504, a clamping voltage (eg, DC voltage or AC voltage) is applied to the electrostatic clamp assembly. At block 506, radiation is emitted to the substrate while the substrate is disposed on the electrostatic chuck assembly. Radiation can be characterized by an energy larger than the bandgap of the HBR semiconductor or insulating substrate. Radiation can be emitted to the front surface of the substrate or to both rear surfaces of the substrate. In this way, the radiation may be of sufficient energy and sufficient intensity to generate charge carriers within the substrate such that a target clamping force is produced when a clamping voltage is applied.

Figure 21 shows another process flow 550 according to additional embodiments. At block 552, a high bandgap substrate is provided on the electrostatic chuck assembly. At block 554, high energy radiation is emitted to the substrate while the substrate is positioned on the electrostatic chuck assembly. The high energy radiation may have an energy above the bandgap of the substrate, where the energy may be sufficiently above the bandgap to generate charge carriers in the substrate. Non-limiting examples of high energy radiation include UV radiation or VUV radiation. At block 556, an AC clamping voltage waveform characterized by amplitude, frequency, and rise time is applied to the electrostatic clamping assembly. In this way, the AC clamping voltage waveform in combination with high energy radiation can be configured to generate enough photocarriers to establish a target clamping pressure during a half cycle of the AC clamping voltage waveform.

FIG. 22 illustrates another exemplary process flow 600 . At block 602, a high bandgap substrate is provided on an electrostatic chuck assembly. At block 604, the clamping current signal is detected to determine the substrate type of the high bandgap substrate. At method 606, high energy radiation is emitted to the substrate while the substrate is disposed on the electrostatic chuck assembly. At block 608, an AC clamp voltage waveform is applied from the AC power source to the electrostatic clamp assembly. In this way, the AC clamp voltage waveform can be characterized by a narrow high voltage pulse portion and a longer duration low voltage portion, wherein the maximum charge delivered by the high voltage pulse portion is limited below a predetermined threshold.

FIG. 23 illustrates another exemplary process flow 650 . At block 652, the substrate is clamped to the substrate table by an electrostatic clamp assembly. The substrate can be a silicon substrate, a silicon carbide substrate, a glass substrate, or other substrates. The substrate can be a low bandgap substrate or a high bandgap substrate. At block 654, the substrate is processed while the substrate is on the substrate table. The treatment can be any suitable process. At block 656, at the end of the process, high energy radiation is shot at the substrate to remove static charges. High energy radiation may be energy above the bandgap of the substrate. High energy substrates can be applied while removing the clamping voltage generated by the electrostatic clamp assembly.

FIG. 24 illustrates another exemplary process flow 700 . At block 702, a substrate is clamped to a substrate table using an electrostatic clamp in combination with high energy radiation. The high energy radiation may have an energy above the bandgap of the substrate and an intensity sufficient to generate charge carrier motion in the substrate sufficient to generate a target clamping pressure. At block 704, the substrate is scanned while using the substrate table during a processing interval. At block 706, a scan of the substrate by the substrate is synchronized with a scan of the radiation beam. In some variations, the radiation beam may be a wide beam covering a majority of the substrate, wherein scanning the radiation beam involves scanning the wide beam at the same rate as the substrate is scanned to ensure that most of the radiation beam or completely intercepted by the substrate. In some variations, the radiation beam may be a narrow beam covering a narrow portion of the substrate, wherein scanning the radiation beam involves rapidly scanning the narrow beam back and forth to cover the target portion of the substrate, creating a beam umbrella or beam envelope while superimposing a slower scan rate at the same rate as the scan over the substrate to ensure that most or all of the beam envelope is intercepted by the substrate as the substrate moves.

While the foregoing embodiments have focused on applications related to substrate clamping, in further embodiments, devices and techniques may be applied to reduce substrate charging in various processing environments. In various processing devices, including plasma devices, ion beam devices, and others, charged particles, including ions (ionic species) or electrons, are used as processing species to treat substrates, wherein to charge. This situation is particularly acute for new types of substrates, such as SiC substrates, silicon-on-insulator (SOI) substrates, and glass substrates, where such substrates can generate charges during processing that are not The low mobility of the charge carriers is removed.

According to embodiments of the present disclosure, an illumination system such as those disclosed with respect to FIGS. 1-13 and 15 may be provided in a processing apparatus to facilitate charge removal during substrate processing. FIG. 25 illustrates an embodiment of a processing system 800 for processing a substrate 112 . According to various non-limiting embodiments, the processing system 800 may include a source 806 to emit a processing species, such as an ion beam, electron beam, or plasma, onto the substrate 112 . For illustrative purposes only, the example shown in FIG. 26 shows the process beam 807 being emitted to the substrate 112 . Substrate 112 may be supported by substrate holder 810 . In a general embodiment, the substrate is scanned along direction 808 to expose the entire front surface 112A of the substrate 112 , for example when the processing beam 807 does not cover the entire substrate 112 . As generally set forth above, an illumination system 106 may be provided to project illumination onto a major surface of a substrate 112 . According to some embodiments, substrate 112 may be an electrical insulator, a high bandgap semiconductor, or other substrate with relatively low charge mobility. For example, during processing by processing beam 807, substrate 112 may tend to accumulate charge on front surface 112A. Illumination system 106 can be activated to emit radiation 120 onto substrate 112 to reduce or eliminate charge buildup on substrate 112 and thus improve substrate processing.

In some embodiments, the following procedure may be followed. A substrate 112 is provided in a process chamber 802 . Radiation 120 is emitted from illumination system 106 to substrate 112 while the substrate is disposed in process chamber 802 . While the substrate is disposed in the process chamber 802 , the substrate 112 is processed such that a processing species is provided to the substrate 112 within the processing beam 807 separately from the radiation 120 provided by the illumination system 106 . According to certain embodiments, at least a portion of the radiation energy of radiation 120 is equal to or greater than 2.5 eV to produce an energy above the bandgap of a given substrate. Although radiation 120 and treatment beam 807 are emitted to the substrate at the same time as each other, the duration of radiation 120 and treatment beam 807 need not be the same, and radiation 120 can be initiated before or after initiation of treatment beam 807 and can be terminated after treatment beam 807 Radiation 120 is terminated before or after.

This embodiment provides at least the following advantages. First, practical methods have been developed to achieve electrostatic clamping of high-resistivity substrates, for which known electrostatic clamping is not suitable. Another advantage is that in configurations in which the illumination source is mounted on the substrate table, the illumination of the substrate is not affected by substrate movement (eg substrate scanning). Another advantage is that the application of novel voltage waveforms can further enhance the electrostatic clamping process. Yet another advantage is that using light irradiation to enhance electrostatic clamping can also be used to enhance de-clamping. Additionally, as another advantage, irradiation can be used to increase and control the substrate temperature.

The scope of the present disclosure is not limited by the specific examples described herein. In fact, through the above description and accompanying drawings, for those of ordinary skill in the art, in addition to the embodiments and modifications described herein, other various embodiments of the present disclosure and various modifications to the present disclosure will also be obvious. Accordingly, such other embodiments and modifications are intended to fall within the scope of this disclosure. Furthermore, although the disclosure has been described herein in the context of a particular implementation, in a particular environment, and for a particular purpose, those of ordinary skill in the art will recognize that the disclosure is not so limited in utility and may The present disclosure can be beneficially practiced for any number of purposes and in any number of environments. Accordingly, the claims set forth above should be construed in view of the full scope and spirit of the disclosure described herein.

Claims (20)

1. A method comprising: providing a substrate on the jig; and emitting radiation from an illumination source onto the substrate while the substrate is positioned on the fixture during substrate processing, wherein the radiation comprises radiation energy, wherein at least a portion of the radiation energy is equal to or greater than 2.5 eV. 2. The method of claim 1, comprising filtering the radiation to block portions of the radiation having energies less than 2.5 eV. 3. The method of claim 1, the illumination source comprising a diode laser source, another type of solid state laser, or an excimer laser. 4. The method of claim 3, comprising emitting the radiation by pulsing the diode laser source. 5. The method of claim 1, the illumination source comprising a deuterium lamp source. 6. The method of claim 1, comprising: The radiation is emitted onto a front side of the substrate, wherein the clamp is an electrostatic clamp, and wherein the electrostatic clamp clamps a back side of the substrate opposite the front side. 7. The method of claim 6, wherein emitting the radiation comprises: emitting a narrow radiation beam onto the substrate, wherein the narrow radiation beam coverage comprises a beam cross-section smaller than the area of the substrate; and The narrow beam of radiation is scanned rapidly over the substrate, wherein the beam of radiation creates a beam envelope covering the substrate. 8. The method of claim 6, wherein emitting said radiation comprises: emit the first beam to the optical mirror; reflecting the first beam to produce a second beam wider than the first beam; and The substrate is positioned relative to the optical mirror, wherein the second beam illuminates the entire front side of the substrate. 9. The method of claim 1, wherein the substrate is a high volume resistivity silicon wafer, a SiC wafer, or a glass substrate. 10. The method of claim 1, comprising: The radiation is emitted to the backside of the substrate, wherein the clamp is an electrostatic clamp, and wherein the electrostatic clamp clamps the backside of the substrate. 11. The method of claim 10, wherein emitting the radiation to the backside of the substrate further comprises: emitting the radiation from a plurality of illumination sources disposed at least partially within the electrostatic chuck . 12. The method of claim 1, wherein the clamp is an electrostatic clamp, the method further comprising: applying a clamping voltage to the electrostatic clamp to clamp the substrate; processing the substrate while the substrate is held by the electrostatic chuck; and, After said processing: removing the clamping voltage from the electrostatic clamp; and directing irradiation of dechucking radiation from an irradiation source onto the substrate while the substrate is positioned on the electrostatic chuck, Wherein the de-chipping radiation comprises de-chipping radiation energy equal to or higher than a threshold energy for generating mobile charges in the substrate. 13. A method comprising: providing the substrate on the electrostatic fixture; emitting radiation from an illumination source to the substrate while the substrate is positioned on the electrostatic chuck; and applying an AC clamping voltage to the electrostatic clamp while the radiation impinges on the substrate, wherein said radiation comprises radiation energy equal to or greater than 2.5 eV. 14. The method of claim 13, wherein the AC clamping voltage is applied at a frequency of less than 10 Hz. 15. The method of claim 13, comprising adjusting a radiation flux of the radiation to produce a clamping force of 50 Torr or greater. 16. The method of claim 13, wherein the substrate is a vitreous silica substrate, and wherein the illumination source comprises a vacuum ultraviolet light source producing a peak wavelength below 150 nm. 17. A method comprising: providing a substrate in the process chamber; emitting radiation from an illumination source onto the substrate while the substrate is disposed in the process chamber; and treating the substrate by providing a treatment substance to the substrate separately from the radiation while the substrate is disposed in the process chamber, wherein the radiation comprises radiation energy, wherein at least a portion of the radiation energy is equal to or greater than 2.5 eV. 18. The method of claim 17, wherein the substrate comprises a SiC substrate, a glass substrate, a silicon oxide substrate, or a silicon-on-insulator substrate. 19. The method of claim 17, wherein providing the treatment species to the substrate comprises ejecting ions toward the substrate. 20. The method of claim 19, wherein ejecting the ions toward the substrate comprises: ejecting the ions to etch the substrate, ejecting the ions to deposit a coating on the substrate layer, or eject the ions to dope the substrate.

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