Method for processing a substrate

Abstract

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

Description

Technical Field

[0001] This embodiment relates to a method of substrate processing, and more particularly to an electrostatic chuck for holding a substrate. Background Art

[0002] Substrate holders such as electrostatic chucks (also known as electrostatic chucks) are widely used in many manufacturing processes, including semiconductor manufacturing, solar cell manufacturing, and the processing of other components. Electrostatic clamping utilizes the principle of electrostatic induction in which electric charges are redistributed in an object due to the direct influence of nearby charges. For example, a positively charged object near an electrically neutral substrate will induce negative charges on the surface of the substrate. Such charges create an attractive force between the object and the substrate. For the clamping of conductive substrates and semiconductor substrates having a relatively low bulk resistivity, the redistribution of charges is easily achieved by applying a voltage to an electrode embedded in an insulator adjacent to the conductive substrate. Thus, electrostatic chucks have been widely used to hold semiconductor substrates such as silicon wafers having a relatively low bulk resistivity.

[0003] One type of electrostatic chuck applies an alternating current (AC) voltage to generate clamping, thereby enabling rapid clamping and unclamping of conductive substrates or low-resistivity semiconductor substrates. However, known direct current (DC) electrostatic chucks or AC electrostatic chucks are ineffective in clamping high-resistivity semiconductor substrates or electrically insulating substrates.

[0004] In addition, substrate charging problems can adversely affect substrate processing (especially for the processing of high-resistance substrates), such as during ion implantation. In addition to electrostatic chucks, non-electrostatic chucks (such as mechanical chucks) may include conductive lift pins and ground pins, and the operation of such pins may be impaired when the substrate being clamped has a high resistance. In addition, in an ion implantation device, charge buildup on the substrate during implantation may require the use of charge compensation (such as an electron flood gun) to counteract the charging of the substrate.

[0005] The present disclosure is provided in view of these and other considerations. Summary of the Invention

[0006] This summary of the invention is provided to introduce a series of concepts that will be further described in the detailed description below in a simplified form. This summary of the invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to assist in determining the scope of the claimed subject matter.

[0007] In one embodiment, a method may include: providing a substrate on a fixture; and directing radiation from an illumination source onto the substrate while the substrate is disposed on the fixture during substrate processing, wherein the radiation includes radiation energy, and wherein at least a portion of the radiation energy is equal to or greater than 2.5 eV.

[0008] In another embodiment, a method may include: providing a substrate on an electrostatic chuck; directing radiation from an illumination source onto the substrate while the substrate is disposed on the electrostatic chuck; and applying an AC clamping voltage to the electrostatic chuck while the radiation impinges on the substrate, wherein the radiation includes radiation energy equal to or greater than 2.5 eV.

[0009] 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; and processing the substrate while the substrate is clamped by the electrostatic chuck. The method may further include: after the processing, removing the clamping voltage from the electrostatic chuck and directing an exposure of unclamping radiation from an illumination source onto the substrate while the substrate is disposed on the electrostatic chuck, wherein the unclamping radiation includes unclamping radiation energy that is equal to or higher than a threshold energy for generating mobile charges in the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A Shows an electrostatic chuck device according to an embodiment of the present disclosure.

[0011] Figure 1B Shows a fixture device according to other embodiments of the present disclosure.

[0012] Figure 1C Shows an example of electrostatic clamping.

[0013] Figure 2 Shows a side view of an electrostatic chuck device according to various embodiments of the present disclosure.

[0014] Figure 3 Shows a side view of another electrostatic chuck device according to various embodiments of the present disclosure.

[0015] Figure 4 Shows a side view of yet another electrostatic chuck device according to various embodiments of the present disclosure.

[0016] Figure 5 Shows a side view of still another electrostatic chuck device according to various embodiments of the present disclosure.

[0017] Figure 6 Shows a side view of an additional electrostatic chuck device according to various embodiments of the present disclosure.

[0018] Figure 7A A side view showing another electrostatic chuck device according to various embodiments of the present disclosure.

[0019] Figure 7B And Figure 7C Showing the geometry of a scanned radiation beam according to two different embodiments.

[0020] Figure 8 A side view showing yet another electrostatic chuck device according to various embodiments of the present disclosure.

[0021] Figure 9 A side view showing an additional electrostatic chuck device according to various embodiments of the present disclosure.

[0022] Figure 10 A side view showing another electrostatic chuck device according to various embodiments of the present disclosure.

[0023] Figure 11 A side view showing another electrostatic chuck device according to various embodiments of the present disclosure.

[0024] Figure 12 A side view showing yet another electrostatic chuck device according to various embodiments of the present disclosure.

[0025] Figure 13 A side view showing a processing system according to various embodiments of the present disclosure.

[0026] Figure 14 Showing the relationship between radiation wavelength and energy.

[0027] Figure 15 Showing an exemplary control system for electrostatic chucking according to some embodiments.

[0028] Figure 16 Showing the relationship between charging time and resistivity for different substrate types.

[0029] Figure 17 Showing an exemplary irradiance curve of a radiation source suitable for use in the electrostatic chuck device of the present embodiment.

[0030] Figure 18 Showing the variation of photocurrent generation with the radiation energy of SiO2.

[0031] Figure 19 Showing another exemplary irradiance curve of a radiation source suitable for use in the electrostatic chuck device of the present embodiment.

[0032] Figure 20 Showing an exemplary process flow.

[0033] Figure 21 Shows another exemplary process flow.

[0034] Figure 22 Shows yet another exemplary process flow.

[0035] Figure 23 Shows an additional exemplary process flow.

[0036] Figure 24 Shows another exemplary process flow.

[0037] Figure 25 Shows an embodiment of a processing system. Detailed Description

[0038] This embodiment provides an apparatus and technique for increasing substrate clamping ability. In various embodiments, a clamping apparatus and a processing system suitable for clamping various substrates including high-resistivity substrates are disclosed. Various embodiments employ a radiation source capable of generating radiation in the visible light as well as shorter wavelengths (including wavelengths in the ultraviolet (UV) range and in the vacuum ultraviolet (VUV) range (<200 nm)). Accordingly, various embodiments provide an apparatus that can be referred to as photo-assisted electron clamping and release of various substrates, including irradiating the substrate with radiation before, during, and after clamping.

[0039] Figure 1A Shows an electrostatic chuck system 100 according to an embodiment of the present disclosure. The electrostatic chuck system 100 can be deployed in any suitable environment where a substrate is clamped for any suitable purpose. In various embodiments, the electrostatic chuck system 100 can be arranged in a substrate chamber 102 to accommodate a substrate 112. In various non-limiting embodiments, the substrate chamber 102 can represent a loading chamber for loading the substrate 112 into the system, a transfer chamber for transferring the substrate 112 between positions, or a process chamber where the substrate 112 will undergo at least one process. Suitable process chambers include chambers for layer deposition on the substrate 112, for etching the substrate 112, for heating the substrate 112, for ion implantation into the substrate 112, or for other suitable processes.

[0040] As Figure 1A shown, the electrostatic chuck system 100 can include a chuck device 104, and the chuck device 104 includes an electrostatic chuck assembly 114. The electrostatic chuck assembly 114 can include known components of a known electrostatic chuck, including a cooling block, a heater, gas channels, electrodes, wiring, and the like. For clarity, only the general components of the electrostatic chuck assembly 114 are shown. As Figure 1AAs shown, the electrostatic chuck assembly 114 may include an insulator portion 108 that directly supports the 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 may be operable to apply a DC voltage or an AC voltage. In some embodiments, the electrostatic chuck system 100 may be used as a known electrostatic chuck for gripping a low resistivity substrate.

[0041] As Figure 1A Further shown, the chuck device 104 may also include an illumination system 106 that is configured to emit radiation (shown as radiation 120) onto the substrate 112. According to various embodiments, the radiation 120 may be characterized by a radiation energy that is equal to or higher than a threshold energy that generates mobile charges in the substrate 112. In this way, while a clamping voltage is applied to the electrostatic chuck assembly 114, the illumination system 106 may generate the radiation 120. Thus, in operation and with reference to Figure 1C , when the substrate 112 is gripped by the electrostatic chuck assembly 114, charges present within the substrate 112 may move to the electrodes of the electrode assembly 110 with an opposite polarity to create a high electric field and generate a large clamping force.

[0042] It should be noted that the time required for such charge movement depends on the resistivity of the substrate 112, as Figure 16 shown. In Figure 16 the resistivity ranges of different types of commonly used substrates and the response times of the charges are shown. The response times are shown for substrates gripped using a clamping voltage without the application of the illumination system 106. A substrate referred to as a "conventional Si wafer" represents the resistivity range of a relatively low resistance silicon wafer (showing resistivity values in the range of approximately 1 Ohm-cm to 1000 Ohm-cm). In this example, the response time is approximately 1 μs to 100 μs. Figure 16 The rise time and clamping period of an AC chuck are also shown. As shown, this rise time is consistent with the response time of a conventional silicon wafer. Figure 16 The response times of charges in high bulk resistivity (HBR) silicon wafers (HBR Si wafers), HBR silicon carbide wafers (HBR SiC), and glass substrates are also shown. It should be noted that in the case of glass substrates, the bulk resistivity of these other substrates extends from more than 10 seconds to 2 seconds up to 108 seconds. These longer response times mean that charges cannot move within these substrates within a time period consistent with the application of an AC voltage. Additionally, even when a DC voltage is applied, the response time is still too slow for practical processing purposes, especially for HBR SiC and glass.

[0043] When the resistivity of the substrate 112 is too high, when the clamping voltage is applied by the electrostatic chuck assembly 114, charges cannot move fast enough to establish the clamping force. Compared with the time scale associated with clamping and handling the substrate 112, the charging time is effectively infinite for an insulating substrate such as a glass wafer, and the duration of such charging time can be on the order of seconds to minutes. As a result, without using the illumination system 106, substantially no substrate charge is generated in response to the applied clamping voltage, such that the clamping force is almost zero.

[0044] Accordingly, in the case of using the chuck device 104, substrates including HBR semiconductor wafers and glass can be clamped. In addition to solving the clamping problem of high-resistivity substrates, the chuck device 104 helps to solve another problem, namely the generation of undesired charges on high-resistivity substrates, where removing such charges can be very difficult, for example, due to triboelectricity. By generating mobile charges on the substrate 112, the chuck device 104 also facilitates the unclamping of the substrate. The high resistivity of insulating materials stems from different factors. First, these materials typically have a very large electron bandgap. For example, for silicon oxide (e.g., SiO2), the bandgap is approximately 8 eV. Different from dopants in semiconductors, impurities in insulators also have a much higher ionization energy. Thus, the concentration of mobile charges in such substrates is very low. Second, many common insulating materials are amorphous (e.g., silica glass). The lack of a periodic crystal structure results in a relatively low charge mobility. According to an embodiment of the present disclosure, in the case of applying radiation 120, the conductivity of a high-resistivity substrate (e.g., glass) can be significantly enhanced by transferring sufficient energy to the electrons of the high-resistivity material such that the electrons enter a so-called extended state in the conduction band. For narrow-bandgap semiconductors containing Si, low-energy photons (e.g., photons in infrared irradiation) provide sufficient energy to overcome the bandgap. For wide-bandgap semiconductor materials such as SiC, long-wave UV radiation (315 nm to 400 nm) can provide sufficient energy to overcome the bandgap and generate charge carriers. For such wavelength ranges, in various non-limiting embodiments, the illumination system 106 can be implemented as a light source, including a laser diode, a light-emitting diode (LED), an arc lamp, or other sources.

[0045] According to additional embodiments, for substrates generally referred to as insulating substrates (such as glass substrates), other types of radiation sources may be used for the irradiation system 106, as further elaborated in detail below. Generally, the irradiation system 106 will be arranged to provide radiation 120 with sufficient energy to generate mobile charges for the type of substrate used as substrate 112. However, in various non-limiting embodiments, the irradiation system 106 may be configured to hold at least the following substrate types: 1) Conventional silicon wafers: resistivity < 1000 ohm-cm; 2) High resistivity silicon / or silicon-on-insulator (SOI) wafers: resistivity from 1000 ohm-cm to 100,000 ohm-cm; 3) Silicon carbide wafers: available resistivity up to 1E9 ohm-cm; and 4) Glass: resistivity > 1E12 ohm-cm; 5) Silicon on glass.

[0046] According to various embodiments of the present disclosure, the irradiation system 106 is arranged to provide irradiation to the main surface of the substrate 112 (including the front surface 112A on the front side or the back surface 112B on the back side). According to different embodiments, the radiation 120 may be provided directly in a line-of-sight manner, the radiation 120 may be provided by reflection, the radiation 120 may be provided by blanket irradiation of the substrate, by scanning the substrate, by scanning the irradiation source, or a combination of the methods. Ideally, high-intensity uniform light irradiation over the entire substrate is useful. Due to limitations in the configuration of the light source and the electrostatic chuck device, certain embodiments provide novel configurations to maximize the efficiency of light generation in the substrate. In the embodiments shown below Figures 2 to 8 different electrostatic chuck systems are shown, where a substrate stage 202 is shown, which may include an electrostatic chuck as generally described above for Figure 1A general elaboration.

[0047] Turning to Figure 1B , a chuck device 150 according to an additional embodiment of the present disclosure is shown. In this case, the chuck device 150 includes a mechanical chuck 154 (optionally including stand offs 156) to hold the substrate 112 using any suitable mechanical components. The chuck device 150 includes the above-described irradiation system 106. In operation, while the substrate 112 is held by the mechanical chuck 154, the radiation 120 may be emitted onto the substrate 112 to increase the mobile charges in the substrate 112 and assist in the processing of the substrate, such as providing better electrical conductivity between the substrate 112 and lift pins or ground pins (not shown separately) or by reducing the surface charging of the substrate 112.

[0048] Figure 2A side view of an electrostatic chuck system 200 in accordance with various embodiments of the present disclosure is shown. In this embodiment, the illumination system 201 is positioned to emit radiation 208 onto the front surface of the substrate 112. Although in some embodiments the substrate stage 202 may be fixed, in other embodiments the substrate stage 202 may include a scanning assembly (e.g., a known scanning assembly (not shown)) to scan the substrate 112 along at least one direction. Similarly, in some embodiments, the radiation 208 may be provided as a fixed beam that is arranged to cover the entire substrate. In some embodiments in which the substrate stage 202 is arranged to scan the substrate, for example, along the Y-axis of the Cartesian coordinate system shown, the radiation 208 may be provided in a manner that covers the entire scan range of the substrate 112, as Figure 2 shown. For example, the illumination system 201 may include a component referred to as an illumination source 204, including a component that generates radiation 208 at a suitable energy to generate photo carriers in the substrate 112, where examples of different illumination sources are elaborated in detail below. The illumination source 204 may generate radiation as a beam having a specific size. In some embodiments, the beam emitted by the illumination source 204 may be large enough or may be expandable to become large enough to cover the substrate 112.

[0049] In other embodiments, the illumination system 201 may further include an optical system 206 disposed between the illumination source 204 and the substrate 112 to expand the radiation beam received from the illumination source 204 and the radiation beam used to generate the radiation 208 to cover the entire substrate 112. An example of an optical system suitable for the optical system 206 is a set of refractive optics, such as optical lenses. In this embodiment and the following embodiments, "optical system" will provide the ability to handle radiation in the UV range, which means that refractive optics will mean optical devices for refracting UV radiation, and mirror optics will be suitable for reflecting UV radiation.

[0050] Figure 3 A side view of an electrostatic chuck system 220 in accordance with various embodiments of the present disclosure is shown. In this embodiment, the illumination system 211 is positioned in a different manner to emit radiation 212 onto the front surface of the substrate 112. Although in some embodiments the substrate stage 202 may be fixed, in other embodiments, the substrate stage 202 may include a scanning assembly (e.g., a known scanning assembly (not shown)) to scan the substrate 112 along at least one direction. Similarly, in some embodiments, the radiation 212 may be provided as a fixed beam that is arranged to cover the entire substrate. In some embodiments in which the substrate stage 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 that covers the entire scan range of the substrate 112, asFigure 3 as shown. For example, the illumination system 211 may include the illumination source 204 discussed above for Figure 2 discussion. The illumination source 204 may generate radiation as a beam having a specific size. In such a configuration, the illumination source 204 may emit radiation as a beam that does not initially project towards the substrate 112. The illumination system 211 may further include an optical system 210 that is arranged to reflect the beam generated by the illumination source 204 and project the reflected beam as radiation 212 onto the substrate 112. The optical system 210 may include optical mirrors, and in some embodiments, the optical mirrors may be arranged as expander mirrors to expand the radiation beam received from the illumination source 204, reflect and expand the radiation beam for generating radiation 212 to cover the entire substrate 112. In additional embodiments, the illumination system may include a combination of refractive optics and mirror optics. The selection of the optics for illumination may be guided by considering the spacing and placement of the elements and the efficiency of generating illumination that covers the substrate 112.

[0051] Figure 4 A side view of another electrostatic chuck system 250 in accordance with various embodiments of the present disclosure is shown. In this example, the electrostatic chuck system 250 may include the substrate stage 202 and the illumination source 204 generally described above. The electrostatic chuck system 250 may additionally include an illumination system 251 having an optical system 252, and the electrostatic chuck system 250 is different from the Figure 2 embodiment shown in that the optical system 252 includes components that provide a scanning capability for the radiation beam received from the illumination source 204. The scanning capability may be provided by, for example, a motorized component. According to various embodiments, a radiation beam 254 may be provided as a beam expanded from an initial beam size.

[0052] According to various embodiments of the present disclosure, the optical system 252 provides beam scanning of the radiation beam 254. In some embodiments, in a configuration where the substrate 112 is scanned, the optical system 252 may also scan the radiation to follow the scan of the substrate 112. For example, the illumination source 204 and the optical system 252 may include refractive optics that generate the radiation beam 254 as a beam having a width that covers the substrate 112.

[0053] The optical system 252 may be further configured with a lens drive mechanism that is arranged to move the optical lens by rotation, translation, or a combination of rotation and translation. For example, the optical system 252 may be further configured with a scanning assembly, where when the substrate 112 is scanned along the Y-axis at a rate of 10 cm per minute, the radiation beam 254 is scanned at the same rate in the same direction so that the radiation beam 254 covers the substrate 112 in any case. In this way, even when the substrate 112 is scanned, the width of the radiation beam 254 emitted onto the substrate 112 does not need to be significantly greater than the substrate width, thus protecting other components in the rest of the chamber that houses the substrate 112.

[0054] In other embodiments, the radiation beam 254 may be provided as a relatively narrow beam compared to the width of the substrate 112 (e.g., a laser beam or a highly collimated incoherent beam). This embodiment is represented by the radiation beam 254, which is shown as having a much smaller width than the width of the 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 254, for example, along the Y-direction, in a manner that provides an average uniform irradiation to cover the entire substrate 112. In an embodiment where the substrate 112 remains fixed, the optical system 252 may thus scan the radiation beam 254 only in a rapid manner to produce a radiation umbrella that covers the fixed substrate.

[0055] Figure 5 A side view of another electrostatic chuck system 260 according to various embodiments of the present disclosure is shown. In this example, the electrostatic chuck system 260 may include the substrate stage 202 and the irradiation source 204 generally described above. The electrostatic chuck system 260 may additionally include an irradiation system 261 having an optical system 262, and since the optical system 262 includes components that provide a scanning capability for the radiation beam received from the irradiation source 204, the electrostatic chuck system 260 is different from Figure 3 the embodiment shown. The scanning capability may be provided by, for example, electric components. According to various embodiments, the radiation 264 may be provided as a beam that expands from an initial beam size.

[0056] According to various embodiments of the present disclosure, the optical system 262 provides scanning of a beam of radiation 264. In some embodiments, in a configuration 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, the illumination source 204 and the optical system 262 may include reflective optics (such as a UV mirror) that produce the radiation 264 as a beam having a width that covers the width of the substrate 112. The optical system 262 may be further configured with a scanning assembly, where when the substrate 112 is scanned along the Y-axis at a given rate, the radiation 264 is scanned in the same direction at the same rate so that the radiation 264 covers the substrate 112 in any case. In this way, even when the substrate 112 is scanned, the width of the radiation 264 incident on the substrate 112 does not need to be significantly greater than the substrate width, thus protecting other components in the rest of the chamber that houses the substrate 112.

[0057] In other embodiments, radiation from the illumination beam may be provided as a beam that is relatively narrow compared to the width of the substrate 112 (such as a laser beam or a highly collimated incoherent beam). This embodiment is represented by Figure 6 the electrostatic chucking system 270 shown in. The substrate stage 202 may be 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 at least along the Y-direction relative to the width of the substrate 112. The illumination source 272 may be a laser source or a collimated incoherent light source. In this embodiment, the optical system 274 may be provided with refractive components to receive and transmit the beam emitted from the illumination source 272 as a narrow beam shown as the radiation beam 276 and scan the radiation beam 276 along, for example, the Y-direction in a manner that provides an average uniform irradiation to cover the entire substrate 112.

[0058] In embodiments in which the substrate 112 remains fixed, the optical system 274 can thus scan the radiation beam 276 only in a rapid manner to produce a radiation umbrella 278 that covers the fixed substrate. In other embodiments in which, for example, the substrate 112 is also scanned along the Y-axis, the optical system 274 can include components that both rapidly scan the radiation beam 276 across the substrate 112 and slowly offset the average position of the radiation beam 276 in synchronization with the movement of the substrate. In this way, the radiation 264 produces a radiation umbrella 278, the size of which along the Y-axis closely corresponds to or matches the size of the substrate along the Y-axis, and the position of the radiation umbrella 278 is arranged such that the radiation umbrella 278 overlies the entire substrate 112 or a desired portion of the substrate 112 without extending beyond the substrate 112. More generally, the electrostatic chucking system 270 can include synchronization components to synchronize the movement of the optical lens with the movement of the substrate stage scanner (shown by the double arrows) such that the radiation beam remains aligned with the front side of the substrate 112 during the scan of the substrate 112. In Figure 7A Another embodiment is shown in which the radiation beam is provided as a scanned narrow beam. This embodiment is represented by the electrostatic chucking system 280, in which the substrate stage 202 can be configured generally as in the previous embodiment. In this embodiment, the illumination system 281 can include an illumination source 272 that produces a narrow beam, as described above for Figure 6 stated. In this embodiment, the optical system 284 can be provided with components that reflect the beam emitted from the illumination source 272 as a narrow beam (shown as the radiation beam 286) and scan the radiation beam 286 along, for example, the Y-direction in a manner that provides an average uniform irradiation to cover the entire substrate 112.

[0059] In embodiments in which the substrate 112 remains fixed, the optical system 284 can thus scan the radiation beam 286 only in a rapid manner (e.g., by rapidly moving or rotating a mirror) to produce a radiation umbrella 288 that covers the fixed substrate. In other embodiments in which, for example, the substrate 112 is also scanned along the Y-axis, the optical system 284 can include components that both rapidly scan the radiation beam 286 across the substrate 112 and slowly offset the average position of the radiation beam 286 in synchronization with the movement of the substrate. In this way, the radiation 264 produces a radiation umbrella 288, the size of which along the Y-axis closely corresponds to or matches the size of the substrate along the Y-axis, and the position of the radiation umbrella 288 is arranged such that the radiation umbrella 288 overlies the entire substrate 112 or a desired portion of the substrate 112 without extending beyond the substrate 112.

[0060] In different embodiments in which the optical system provides the radiation as a scanned narrow radiation beam to the substrate 112, the scanned radiation beam can be provided as a point beam or a strip beam in the plane of the substrate 112 (this means in the X-Y plane, as shown).Figure 7B Embodiments are shown in which the radiation beam 276 or the radiation beam 286 is provided as a strip beam extending along the X-axis. The strip beam may have a length dimension comparable to the length of the substrate 112 along the X-axis, and thus may not be scanned along the X-axis, but only along the Y-axis, to produce the radiation umbrella 278 or the radiation umbrella 288. Figure 7C Embodiments are shown in which the radiation beam 276 or the radiation beam 286 is provided as a point beam, which has a relatively small size compared to the width of the substrate 112 along the X-axis, and thus may be scanned along both the X-axis and the Y-axis to produce the radiation umbrella 278 or the radiation umbrella 288.

[0061] In an additional embodiment, the electrostatic chuck system may include optics that combine a mirror assembly and a refractive assembly to direct a radiation beam onto the substrate.

[0062] Figure 8 A side view of another electrostatic chuck device in accordance with various embodiments of the present disclosure is shown. In this embodiment, an electrostatic chuck system 290 including the substrate stage described above is shown. Different from the embodiments described above, the electrostatic chuck system 290 includes an illumination system 291 that includes a plurality of illumination sources. In Figure 8 the illustrated embodiment, two different illumination sources (shown as illumination source 204A and illumination source 204B) are included, where each illumination source may be configured similarly to the illumination source 204 described above. However, in other embodiments, more than two illumination sources may be employed. In Figure 8 the illustrated configuration, the illumination system 291 includes an optical system 292 that is arranged to direct two radiation beams onto the substrate 112 using a mirror configuration of a mirror system 292A and a mirror system 292B to reflect the radiation generated by the illumination source 204A and the illumination source 204B and shown as radiation 294A and radiation 294B, respectively. In different variants, the optical system 292 may operate similarly to the Figure 3 、 Figure 5 or Figure 7A foregoing embodiments shown, where a wider beam may be reflected onto the substrate 112, a narrower beam is reflected onto the substrate, and a slow scan or a fast scan of the radiation beam is provided as described above. Figure 8 An advantage of the illustrated configuration is that the substrate 112 can be irradiated more uniformly compared to using a single radiation beam. In other embodiments, a plurality of illumination sources may be coupled to a corresponding plurality of refractive optical systems (similar to Figure 2 、 Figure 4 and Figure 6A similar configuration (not shown) can be used to emit multiple radiation beams onto the substrate 112, or multiple illumination sources can be coupled to a combination of at least one refractive optical system and at least one mirror optical system. Such an embodiment can be useful for positioning the optical system within a given processing apparatus in cases where the configuration of other components, such as the substrate stage, for example, and the processing components may impose restrictions on the positions of other components.

[0063] One disadvantage of emitting illumination onto the front surface of the substrate is that while clamping occurs on the back surface of the substrate, photo-carriers tend to be generated near the front surface. For high-mobility materials, since the carriers can traverse the substrate quickly, the generation of photo-generated charge carriers near the front surface does not pose a problem for clamping the substrate. However, for low-mobility materials (such as glass), the charge carriers may take too long to reach the back side of the wafer. In a further embodiment of the present disclosure, the illumination system can be arranged to emit illumination onto the back side of the substrate.

[0064] Figure 9 A side view of an additional electrostatic chuck device according to various embodiments of the present disclosure is shown. In this embodiment, the electrostatic chucking system 300 is arranged with an illumination system 301, wherein at least a portion of the illumination system 301 is embedded within the substrate stage 302. It should be noted that the substrate stage 302 can be configured similarly to the foregoing embodiment of the substrate stage 202 and can include an electrostatic chuck and a scanning component for scanning the substrate stage 302. The illumination system 301 can include a plurality of illumination sources (shown as illumination source 304, illumination source 306, and illumination source 308) distributed at various positions in the X-Y plane. Generally, different illumination sources can be distributed in a one-dimensional array or a two-dimensional array across the substrate stage 302, where the substrate stage includes an opening facing the substrate 112 to directly transmit radiation to the back side including the back surface 112B of the substrate 112 without obstruction. In other words, the gap between the substrate stage 302 and the substrate 112 can be used as a hollow light guide such that radiation, such as UV light, for example, extends beyond the entry point.

[0065] Although Figure 9 the illustrated embodiment shows an illumination system having a plurality of illumination sources, in other embodiments, a single illumination source can be employed. Figure 10A side view of another electrostatic chuck device according to various embodiments of the present disclosure is shown. In this embodiment, an electrostatic clamping system 310 is arranged with an irradiation system 311, wherein a part of the irradiation system 311 is embedded within a substrate stage 312 and a part is located outside the substrate stage 312. It should be noted that the substrate stage 312 can be configured similarly to the foregoing embodiment of the substrate stage 202 and can include an electrostatic chuck and a scanning assembly for scanning the substrate stage 312. The irradiation system 311 includes an irradiation source 314, and the source may represent only one irradiation source. The irradiation source 314 is coupled to a plurality of light guides (optical guides) extending through the substrate stage 312 such that radiation can be directly provided to the back surface 112B of the substrate 112. Generally, different light guides can be distributed in a one-dimensional array or a two-dimensional array across the substrate stage 302, wherein the substrate stage includes a plurality of openings 319 facing the substrate 112 to directly transmit the radiation to the back surface 112B of the substrate 112 without obstruction. 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 to the irradiation source 314 at the distal end and have proximal ends respectively extending through the plurality of openings 319.

[0066] Figure 9 and Figure 10 The foregoing embodiments thus provide an efficient way to directly couple high-energy radiation (such as UV radiation) to the substrate in a uniform manner.

[0067] Figure 11 A side view of another electrostatic chuck device according to various embodiments of the present disclosure is shown. In this embodiment, the electrostatic chuck system 350 includes a substrate stage 352 having an irradiation system 351 embedded within the substrate stage 352. It should be noted that the substrate stage 352 can be configured similarly to the foregoing embodiment of the substrate stage 202 and can include an electrostatic chuck and a scanning assembly for scanning the substrate stage 352. The irradiation system 351 includes an irradiation source 354 embedded within the substrate stage 352 and a set of coupling optical devices (shown as coupling optical devices 356) to receive radiation from the irradiation source 354 and output the radiation 358 in the direction of coupling the radiation 358 to the back surface 112B of the substrate 112. As Figure 11 shown, the gap between the substrate stage 352 and the substrate 112 can act as a hollow light guide.

[0068] Although Figures 2 to 11 the foregoing embodiments are described with respect to electrostatic chucks, in other embodiments, mechanical chucks can be used to implement Figures 2 to 11 the shown irradiation system.

[0069] Figure 12A side view of yet another electrostatic chuck device in accordance with various embodiments of the present disclosure is shown. In this embodiment, the electrostatic chuck system 360 includes an illumination system 361 formed by an illumination source and an electrode assembly 368 disposed within a substrate stage 362. The illumination system 361 is configured to emit radiation 366 toward the back side of the substrate 112 (see back surface 112B). It should be noted that the substrate stage 362 can be configured to include an electrostatic chuck and a scanning assembly for scanning the substrate stage 362. Different from known electrostatic chucks, the substrate stage assembly including the electrostatic chuck assembly can be formed of a material transparent to the radiation 366. For example, the dielectric material for the stage assembly and the electrostatic chuck (including the transparent platen body) and the cooling gas injected into the substrate stage 362 can be made of a material transparent to the UV light used to form the radiation 366.

[0070] As Figure 12 shown, the radiation 366 can form a wide radiation beam that covers most or the entire substrate 112. In this embodiment, the electrostatic chuck portion of the substrate stage 362 (not shown separately) includes an electrode assembly 368 that is arranged as one or more electrodes in the form of a metal screen or a metal mesh, where the transparency of the metal screen is high. In this way, the metal mesh can serve as a uniform electrode system for electrostatic chucking while providing high transparency for the UV radiation or other high-energy radiation emitted by the illumination source 364.

[0071] In additional embodiments of the present disclosure, an electrostatic chucking system (including those embodiments disclosed Figures 1A to 12 herein) or a variant thereof can be deployed in a substrate processing system to process a substrate. In some embodiments, an electrostatic chucking system is provided in a substrate processing chamber such that the substrate can be held while being processed. Figure 13 A side view of one such processing system in accordance with various embodiments of the present disclosure is shown. As shown, the processing system 380 includes a process chamber 382 that can accommodate various components of the electrostatic chucking system, including a substrate stage 385 and an illumination system 391. In the illustrated configuration, the illumination system 391 includes reflective optics for front-side illumination, while in other embodiments, the illumination system can be based on refractive optics for front-side illumination or can be based on back-side illumination, where these various configurations have been elaborated in detail Figures 1A to 12 herein. In this example, the illumination source 388 is disposed outside the substrate stage 385. In different embodiments, the illumination source 388 can be disposed within the process chamber 382, partially disposed within the process chamber 382, or disposed outside the process chamber 382. In Figure 12In the illustrated example, the illumination source 388 emits a beam onto the UV mirror 392, and the UV mirror 392 reflects the beam to emit radiation 396 onto the substrate 112. The geometric configuration of the illumination source 388, the UV mirror 392, and the substrate 112 is arranged to ensure that the source UV beam generated by the illumination source 388 is properly expanded to cover the substrate. Similar to some of the foregoing embodiments, a mirror drive mechanism can be incorporated and arranged to move the optical mirror, such as the UV mirror 392, by rotation, translation, or rotation and translation. As Figure 13 shown in the embodiment of, the scanning motor 390 is mechanically coupled to the UV mirror 392 to scan the UV mirror 392 in a manner that follows the movement or scan of the substrate 112 as described above. In some embodiments, a control system 398 coupled to the UV mirror 392 and the substrate stage 394 is used to control the scanning of the UV mirror 392 and the substrate stage 394 such that the expanded beam (radiation 396) follows the movement of the substrate in a manner that most or all of the radiation 396 is intercepted by the substrate 112. Accordingly, the control system 398 can generate scan control and position sensing signals for controlling the substrate stage 394 and optical beam scan control and position sensing signals for controlling the scanning motor 390 and the UV mirror 392.

[0072] The UV photons of the radiation 396 are provided to generate sufficient mobile charge such that the substrate can be sufficiently clamped by an electrostatic chuck (not shown separately) within the substrate stage 394 even if the substrate has a high bandgap above 2.5 eV.

[0073] The processing system 380 further includes a beam generation assembly 384 to emit an ion beam 386 into the process chamber 382. While the substrate 112 is held in place by the operation of an electrostatic chuck system including the illumination system 391 and the electrostatic chuck within the substrate stage 394, the ion beam 386 can implant ions into the substrate 112. Different from known ion implantation systems, the processing system 380 can be conveniently implanted into a high-resistance or insulating substrate, where the substrate is still electrostatically clamped to the substrate stage.

[0074] Although in Figure 12 the embodiment shown, the beam generation assembly 384 can represent a series of beam line assemblies for transporting the ion beam to the substrate, in other embodiments, the process system of the foregoing embodiment including the electrostatic chuck system can be used to process the substrate for any suitable process (including film deposition, etching, heating, etc.).

[0075] In various embodiments of the present disclosure, a control system 398 or a similar control system can be used to enhance the ability of a UV irradiation system or a high-energy irradiation system to electrostatically clamp a high-resistivity substrate. It should be noted that depending on the configuration of the process chamber and the capabilities of the irradiation source, irradiation of the substrate may need to be synchronized with substrate scanning and the electrostatic clamping of the substrate to improve the effectiveness of the radiation. As previously described, when using a scanned UV beam to irradiate a substrate, the control system 398 can synchronize the scanning of the UV beam with the scanning of the substrate stage. Figure 15 An exemplary control system arrangement 400 for electrostatic clamping according to some embodiments is shown. In this example, a controller 398A is coupled to various components of the electrostatic clamping system. For simplicity, an irradiation system 402 that emits radiation 404 onto the front side of the substrate 112 without using any optical components is shown. It should be noted that the irradiation system 402 can include the components described above for scanning the radiation 404. An electrostatic chuck 406 is disposed in the substrate stage 408 and includes an AC electrode system 410. A motor 412 is coupled to the substrate stage to scan the substrate stage 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. The controller 398A can be coupled to the irradiation system 402, the motor 412, and the AC voltage source 414 to synchronize the operation of these components. For example, the controller 398A can be used to synchronize the timing of irradiating the substrate 112 with the electrical excitation of the substrate. In some embodiments, the controller 398A can be used to emit the AC voltage source 414 to provide a given voltage waveform, the amplitude, AC frequency, and rise time of which are arranged to ensure that sufficient photo-carriers can be generated within the same half-cycle of the AC voltage. The details of the given voltage waveform can be based on the available UV intensity generated by the irradiation system 402.

[0076] In a particular embodiment, the controller 398A can monitor the current clamping signal of the electrostatic chuck 406 to determine the charging condition of the substrate 112. In some embodiments, the clamping current signal can also be used to sense the wafer type before starting substrate clamping.

[0077] Example

[0078] Irradiation source

[0079] According to some embodiments, the irradiation system 106 or any of the other aforementioned irradiation sources can be a visible light source. These embodiments of the visible light source will be particularly suitable for low-bandgap semiconductor substrates (such as silicon, III-V compound semiconductors, II-VI compound semiconductors) in which the bandgap can be lower than approximately 2.5 eV.

[0080] According to other embodiments, the illumination system 106 or any of the other aforementioned illumination sources may be a long wavelength UV source, thereby generating radiation within a wavelength range of between 120 nm and 240 nm (this means an energy range of approximately 3 eV to 4 eV). These embodiments of the UV radiation source will be particularly suitable for wide bandgap semiconductor substrates such as silicon carbide (SiC).

[0081] According to further embodiments, the illumination system 106 or any of the other aforementioned illumination sources may be a VUV source, thereby generating radiation within a wavelength range of between 120 nm and 240 nm or below 120 nm (this means an energy range of approximately 5 eV to 10 eV or above 10 eV). These embodiments of the VUV radiation source will be particularly suitable for insulator substrates such as glass.

[0082] In some instances, any of the aforementioned illumination sources may be a multi-wavelength source, where a wide wavelength range may be obtained from a single illumination source or from multiple different illumination sources. The same electrostatic chucking system can thus employ light sources having multiple wavelengths, where the shortest wavelength source is selected for substrates having the highest energy bandgap, while a source having a longer wavelength and higher radiation flux may be selected for substrates that require less photon energy to bridge the bandgap to achieve a higher conductivity.

[0083] Although in some instances a laser may be employed to generate single wavelength radiation, in other instances, an incoherent light source may be used to generate radiation characterized by a continuous wavelength spectrum or a discrete wavelength spectrum, where the power is highly concentrated around a small number of resonance spectral lines (frequencies).

[0084] In certain instances, a filter may be used to further customize the output wavelength spectrum from the illumination source. For example, for some substrate processing applications, silicon wafers are bonded to glass substrates using a UV-sensitive adhesive. If a filter placed between the illumination source and the substrate filters out the longer wavelengths that are transparent to the glass from the radiation emitted by the illumination source, then the shorter wavelength portion of the radiation can then be used to generate photocarriers within the glass without completely penetrating through the glass and damaging the adhesive.

[0085] Non-limiting examples of suitable laser sources include diode lasers that generate wavelengths as low as 191 nm, other solid-state lasers, excimer lasers (such as ArF, KrF, F2), continuous wave lasers, pulsed lasers, and the like.

[0086] Examples of suitable incoherent sources include deuterium lamps, electrodeless lamps (including line sources or continuous wavelength sources). An example of the output spectrum of a deuterium lamp source is in Figure 19As shown, certain details are omitted for clarity. The output of such a source may be suitable for generating charge carriers in an insulator having a bandgap higher than about 6 eV. Some examples of commercially available resonance line sources are shown in Table I, including the type of radiation source and the radiation wavelength. Some examples of commercially available continuum sources are shown in Table II.

[0087] (nm) Hydrogen 121.6 Krypton 116.5 123.6 Xenon 129.6 147.0 Mercury 184.9 253.7 Iodine Several

[0088] Table I

[0089] (nm) Argon 110-140 Krypton 127-160 Xenon 150-190

[0090] Table II

[0091] In one example, a VUV argon continuum source is used as the irradiation source to assist in the electrostatic chucking of a glass or fused silica substrate. Fused silica has a bandgap of approximately 8 eV, and this bandgap requires a light source with a wavelength <150 nm to generate photo carriers. Figure 18 The photocurrent generated by the glass substrate as a function of photon energy is shown. As shown, no photocurrent is generated below 8 eV, and the photon energy gradually increases until it reaches 9 eV. Above this energy, the photocurrent increases rapidly and reaches saturation at 10 eV or above 10 eV. A reference dashed line at 9.5 eV is shown. In one embodiment, an ArCM-LHP high-power argon continuum source can be used to generate an output spectrum as Figure 17 shown. The output spectrum is idealized to omit certain minor details while showing the general characteristics of the argon emission spectrum. As shown, the peak wavelength is in the range between 116 nm and 140 nm, where most of the integrated intensity of the broad emission spectrum is at wavelengths below approximately 133 nm (represented by the dashed line), corresponding to an energy of 9.5 eV or greater than 9.5 eV. This energy range matches the energy range in which significant photocurrent is generated in the glass, as Figure 18 shown. Such a source can be commercially available with a relatively compact footprint and can be easily fitted into a common processing chamber.

[0092] UV mirror

[0093] In one example, an aluminum mirror with an MgF2 coating can be used as a UV mirror to achieve high reflectivity in the UV range and the VUV range. Commercially available mirrors based on such materials can generate a reflectivity higher than about 75% in the wavelength range from at least 300 nm down to 120 nm, thus providing a high reflectivity for the initial UV beam. Such high reflectivity will facilitate beam expansion and steering using well-known methods for visible light mirror systems.

[0094] AC chucking of the glass substrate using an argon arc lamp is used to achieve electrostatic chucking:

[0095] As described above, in the absence of optically generated carriers such as those generated according to the foregoing embodiments, when attempting to grip an insulating substrate (dielectric substrate), the clamping electrodes of an electrostatic chuck (electron chuck) establish an electric field throughout the dielectric.

[0096] Using the front-side 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 toward the back surface of the substrate (see Figure 1C ). As a result of this process, the electric field in the gap between the substrate and the electron chuck is enhanced. In the absence of charge carrier generation, 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 1C , 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 typically much smaller than the electrode spacing. An electric field enhancement of 10 to 100 times can be easily achieved, which corresponds to a clamping force enhancement of 100 to 10,000 times. Therefore, a useful goal is to establish a sufficiently high surface charge density in a sufficiently short time to realize the potential benefits of increased clamping force. For example, for effective AC clamping, the charge accumulation time needs to be much shorter than the period of the applied AC voltage.

[0097] In the following calculations, it is assumed that a known ArCM-LHP lamp is used as the illumination source that generates a radiation spectrum as shown in Figure 18 , where the lamp can transfer 6×10 16 photons / second / steradian with an electron energy above the SiO2 bandgap of about 8 eV and an output angle 2θ = 45° corresponding to a fixed angle . For different output angles and photon fluxes, as will be understood by those skilled in the art, the calculations can be adjusted quantitatively. A UV mirror can also be used to introduce reflection losses into the beam output from the lamp. In addition, it can be assumed that the extended beam area is slightly larger than the substrate area, which will also reduce the utilization rate of the beam flux. It is assumed that mirror losses together with out-of-substrate beam losses result in a 50% loss of the 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 for a 300 mm wafer 2。The transport of optically generated carriers in silica has been extensively studied previously by experimental and numerical methods. Optical conduction is a complex process. The conduction current is affected by the following factors: optical absorption rate, quantum yield, lifetime of mobile carriers (which depends on the recombination rate and trapping rate and can be very different for electrons and holes), electron and hole mobilities (which can differ by many orders of magnitude), space charge accumulation in the insulator, and charge transfer across the interface between the substrate and the electron clamp. Therefore, it is not appropriate and reliable to estimate the current based on fundamental material properties. Instead, the current calculation in this article is based on experimentally measured photocurrent. In one particular instance, the electron clamp 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 value, a conduction current density of 7.6×10 11 photons / second / cm 2 will generate a conduction current density of 7.6×10 -9 A / cm 2 . In this instance, a higher lamp intensity (2×10 13 photons / second / cm 2 ) was used, and the current density was estimated to be J = 3×10 -7 A / cm 2 . Under experimental conditions where the target clamping pressure is 50 torr, the charge density required to generate such a clamping force is given by:

[0098]

[0099] Therefore, the characteristic charging time in this instance is given by:

[0100]

[0101] This time is fast enough for low-frequency AC excitation, such as having 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 charging time is an estimate of the order of magnitude of the response time using the actual electronic design of the electron clamp and a commercially available VUV source. The estimate shows the feasibility of achieving practical AC clamping of insulating glass wafers using the above method. In other instances, by using multiple light sources to increase the VUV intensity and optimizing the electronic design of the electron clamp and increasing the electric field, the charging time can be shortened to less than 0.1 second.

[0102] Clamping of high-resistivity Si wafers and SiC wafers

[0103] As mentioned above, commercially available HBR silicon wafers can exhibit a resistivity in the range of 100 kOhm-cm. For SiC substrates, a resistivity of 10 9Ohm-cm. However, in an actual system for generating photo-carriers in a commonly used HBR semiconductor substrate, a UV light source can be employed, where, since the band gaps in Si and SiC are much smaller than that in SiO2, the main energy output is at a wavelength slightly longer (>250 nm) than the energy output of the SiO2 substrate. Additionally, compared with glass, crystalline semiconductors such as Si and SiC have high electron and hole mobilities and fewer defects that cause trapping, and such a structure also helps to reduce the transit time of photo-carriers under an electric field. Therefore, assuming that the experimental-based results above indicate that the charging time of SiO2 is about 0.1 second, for HBR Si substrates and HBR SiC substrates, a charging time significantly less than this time can be achieved, which can be realized by using the exemplary irradiation sources and fixture devices disclosed herein.

[0104] Although the foregoing embodiments focus on using high-energy irradiation to achieve enhanced clamping of a high-resistivity substrate, enhanced unclamping can also be achieved according to additional embodiments. In other words, when a semiconductor substrate or an insulating substrate is clamped using an electrostatic chuck, in the case where the substrate is to be unclamped, the clamping voltage can be removed. According to the embodiments disclosed above, to enhance the unclamping of the substrate, photo-carriers can be generated by exposure to an irradiation source. In this way, the decay rate of the previously established electric field and the removal of certain charges (such as neutralizing residual static charges) can be accelerated. Such enhancement can be applied to "conventional" semiconductor substrates having a relatively low band gap (e.g., in the visible light range), as well as HBR semiconductor substrates and insulator substrates.

[0105] Figure 20 An exemplary process flow 500 is shown. At block 502, a substrate is provided on an electrostatic chuck assembly. In some embodiments, the substrate can be an HBR semiconductor substrate or an insulating substrate. At block 504, a clamping voltage (e.g., a DC voltage or an AC voltage) is applied to the electrostatic chuck assembly. At block 506, radiation is emitted onto the substrate while the substrate is disposed on the electrostatic chuck assembly. The radiation can be characterized by an energy greater than the band gap of the HBR semiconductor substrate or the insulating substrate. The radiation can be emitted onto the front surface of the substrate or both back surfaces of the substrate. In this way, the radiation can have sufficient energy and sufficient intensity to generate charge carriers in the substrate such that a target clamping force is generated when the clamping voltage is applied.

[0106] Figure 21Another process flow 550 according to an additional embodiment is shown. At block 552, a high bandgap substrate is provided on an electrostatic chuck assembly. At block 554, high energy radiation is emitted onto the substrate while the substrate is disposed on the electrostatic chuck assembly. The high energy radiation may have an energy higher than the bandgap of the substrate, where the energy may be high enough 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 chucking voltage waveform is applied to the electrostatic chucking assembly, the AC chucking voltage waveform being characterized by an amplitude, a frequency, and a rise time. In this way, the AC chucking voltage waveform in combination with the high energy radiation may be configured to generate sufficient photo-carriers to establish a target chucking pressure during a half cycle of the AC chucking voltage waveform.

[0107] Figure 22 Another exemplary process flow 600 is shown. At block 602, a high bandgap substrate is provided on an electrostatic chuck assembly. At block 604, a chucking current signal is detected to determine the substrate type of the high bandgap substrate. At method 606, high energy radiation is emitted onto the substrate while the substrate is disposed on the electrostatic chuck assembly. At block 608, an AC chucking voltage waveform is applied from an AC power source to the electrostatic chucking assembly. In this way, the AC chucking voltage waveform may be characterized by a narrow high voltage pulse portion and a low voltage portion of a longer duration, where the maximum charge transferred by the high voltage pulse portion is limited to be lower than a predetermined threshold.

[0108] Figure 23 Another exemplary process flow 650 is shown. At block 652, a substrate is chucked to a substrate table by an electrostatic chuck assembly. The substrate may be a silicon substrate, a silicon carbide substrate, a glass substrate, or other substrate. The substrate may 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 processing may be any suitable process. At block 656, at the end of the processing, high energy radiation is emitted onto the substrate to remove static charges. The high energy radiation may be an energy higher than the bandgap of the substrate. The high energy substrate may be applied while removing the chucking voltage generated by the electrostatic chuck assembly.

[0109] Figure 24Another exemplary process flow 700 is shown. At block 702, a substrate is clamped to a substrate stage using an electrostatic chuck in combination with high energy radiation. The high energy radiation may have an energy higher than the bandgap of the substrate and an intensity sufficient to generate charge carrier movement in the substrate sufficient to generate a target clamping pressure. At block 704, the substrate is scanned while using the substrate stage during a processing interval. At block 706, the scanning of the substrate by the substrate is synchronized with the scanning of a radiation beam. In some variations, the radiation beam may be a wide beam that covers most of the substrate, where scanning of the radiation beam involves scanning the wide beam at the same rate as the scanning of the substrate to ensure that most or all of the radiation beam is intercepted by the substrate. In some variations, the radiation beam may be a narrow beam that covers a narrow portion of the substrate, where scanning of the radiation beam involves rapidly scanning the narrow beam back and forth to cover a target portion of the substrate, thereby creating a beam umbrella or beam envelope, while superimposing a slower scanning rate at the same rate as the scanning of the substrate to ensure that most or all of the beam envelope is intercepted by the substrate as the substrate moves.

[0110] Although the foregoing embodiments focus 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 other devices), charged particles (including ions (ionic species) or electrons) may be used as processing species to process a substrate, where charging may occur in the substrate during processing. This situation is particularly acute for novel substrates (such as SiC substrates, silicon-on-insulator (SOI) substrates, and glass substrates), where such substrates may generate charge during processing and the charge is not removed due to the low mobility of charge carriers in such substrates.

[0111] According to embodiments of the present disclosure, an illumination system (such as those Figures 1A to 13 and Figure 15 disclosed) may be provided in a processing device to facilitate charge removal during substrate processing. Figure 25An embodiment of a processing system 800 for processing a substrate 112 is shown. According to various non - limiting embodiments, the processing system 800 may include a source 806 to eject a processing material, such as an ion beam, an electron beam, or a plasma, onto the substrate 112. For illustrative purposes only, the example shown in FIG. 26 shows a processing beam 807 ejected onto the substrate 112. The substrate 112 may be supported by a substrate holder 810. In general embodiments, for example when the processing beam 807 does not cover the entire substrate 112, the substrate is scanned along direction 808 to expose the entire front surface 112A of the substrate 112. As generally described above, an illumination system 106 may be provided to eject illumination onto the major surface of the substrate 112. According to some embodiments, the substrate 112 may be an electrical insulator, a high - bandgap semiconductor, or other substrate having a relatively low charge mobility. For example, during processing by the processing beam 807, the substrate 112 may tend to accumulate charge on the front surface 112A. The illumination system 106 may be activated to eject radiation 120 onto the substrate 112 to reduce or eliminate charge accumulation on the substrate 112 and thus improve substrate processing.

[0112] In some embodiments, the following process may be followed. Provide the substrate 112 in the process chamber 802. When the substrate is disposed in the process chamber 802, eject radiation 120 from the illumination system 106 onto the substrate 112. When the substrate is disposed in the process chamber 802, process the substrate 112 such that a processing material is provided to the substrate 112 separately from the radiation 120 provided by the illumination system 106 within the processing beam 807. According to a particular embodiment, at least a portion of the radiation energy of the radiation 120 is equal to or greater than 2.5 eV to produce an energy above the bandgap of a given substrate. Although the radiation 120 and the processing beam 807 are ejected onto the substrate simultaneously with each other, the durations of the radiation 120 and the processing beam 807 need not be the same, and the radiation 120 may be started before or after starting the processing beam 807, and may be terminated before or after terminating the processing beam 807.

[0113] This embodiment provides at least the following advantages. First, a practical method has been developed to achieve electrostatic chucking of high - resistivity substrates where known electrostatic chucking is not suitable. Another advantage is that in a configuration where the illumination source is mounted on the substrate stage, the illumination of the substrate is not affected by substrate movement (such as substrate scanning). Another advantage is that the application of a novel voltage waveform can further enhance the electrostatic chucking process. Yet another advantage is that the use of optical illumination to enhance electrostatic chucking can also be used to enhance un - chucking. Additionally, as another advantage, illumination can be used to increase and control the substrate temperature.

[0114] The scope of the present disclosure is not limited to the specific embodiments described herein. In fact, from the above description and the accompanying drawings, various other embodiments of the present disclosure and various modifications to the present disclosure will be apparent to those of ordinary skill in the art in addition to the embodiments and modifications described herein. Therefore, these other embodiments and modifications are all intended to fall within the scope of the present disclosure. In addition, although the present disclosure has been described herein for a particular purpose in the context of a particular implementation in a particular environment, those of ordinary skill in the art will recognize that the utility of the present disclosure is not limited thereto and that the present disclosure can be beneficially implemented for any number of purposes in any number of environments. Therefore, the claims described above should be understood in light of the full scope and spirit of the present disclosure described herein.

Claims

1. A method for processing a substrate, comprising: Provide a substrate on an electrostatic chuck; And During substrate processing, when the substrate is disposed on the electrostatic chuck, emit radiation from an irradiation source onto the substrate, Wherein the radiation includes radiation energy, and at least a portion of the radiation energy is equal to or greater than 2.5 eV, Wherein the radiation is emitted onto a front side of the substrate, and the electrostatic chuck holds a rear side of the substrate opposite to the front side, Wherein the radiation is a narrow radiation beam, and the narrow radiation beam includes a beam cross-section smaller than an area of the substrate; And Rapidly scan the narrow radiation beam above the substrate, wherein the narrow radiation beam generates a beam envelope to cover the substrate.

2. The method according to claim 1, comprising: Filter the radiation to block a portion of the radiation having a radiation energy less than 2.5 eV.

3. The method according to claim 1, wherein the irradiation source comprises a diode laser source, another type of solid-state laser or an excimer laser.

4. The method according to claim 3, comprising: Emit the radiation by pulsing a diode laser source.

5. The method according to claim 1, wherein the irradiation source comprises a deuterium lamp source.

6. A method for processing a substrate, comprising: Provide a substrate on an electrostatic chuck; And During substrate processing, when the substrate is disposed on the electrostatic chuck, emit radiation from an irradiation source onto the front side of the substrate, Wherein the radiation includes radiation energy, and at least a portion of the radiation energy is equal to or greater than 2.5 eV, Wherein the electrostatic chuck holds a rear side of the substrate opposite to the front side, Wherein emitting the radiation includes: Emit a first beam onto an optical mirror; Reflect the first beam to generate a second beam wider than the first beam; and Position the substrate relative to the optical mirror, wherein the second beam irradiates the entire front side of the substrate.

7. The method according to claim 1 or 6, wherein the substrate is a high-bulk-resistivity silicon wafer, a SiC wafer or a glass substrate.

8. The method according to claim 1 or 6, comprising: Emit the radiation onto the rear side of the substrate.

9. The method according to claim 8, wherein emitting the radiation onto the back side of the substrate further comprises: Emit the radiation from a plurality of irradiation sources at least partially disposed within the electrostatic chuck.

10. The method according to claim 1 or 6, further comprising: Apply a clamping voltage to the electrostatic chuck to hold the substrate; Process the substrate while the electrostatic chuck holds the substrate; And, After processing the substrate: Remove the clamping voltage from the electrostatic chuck; And When the substrate is disposed on the electrostatic chuck, emit irradiation of unclamping radiation from the irradiation source onto the substrate, Wherein the unclamping radiation includes unclamping radiation energy, and the unclamping radiation energy is equal to or higher than a threshold energy for generating mobile charges in the substrate.

11. A method for processing a substrate, comprising: Provide a substrate on an electrostatic chuck; When the substrate is disposed on the electrostatic chuck, emit radiation from an irradiation source onto the substrate; Apply an AC clamping voltage to the electrostatic chuck while the radiation impinges on the substrate; And Adjust a radiation flux of the radiation to generate a clamping force of 50 Torr or greater than 50 Torr, Wherein the radiation includes radiation energy equal to or greater than 2.5 eV.

12. The method according to claim 11, wherein the AC clamping voltage is applied at a frequency less than 10 Hz.

13. The method according to claim 11, wherein the substrate is a silica glass substrate, and wherein the irradiation source comprises a vacuum ultraviolet light source that generates a peak wavelength below 150 nm.

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