Electrostatic clamp with charge control assembly

Abstract

The electrostatic clamp system may include a conductive base, a ceramic body having an inner surface attached to the conductive base and an outer surface facing a substrate, the ceramic body including an electrode assembly, and a charge control assembly defining a conductive structure, the charge control assembly being isolated from the electrode assembly and extending through the conductive base to the upper surface of the outer surface of the ceramic body.

Description

Technical Field

[0001] Cross - Reference to Related Applications

[0001] This application claims priority to U.S. Patent Application No. 18 / 508,077, filed November 13, 2023, and claims the benefit of priority to U.S. Provisional Application No. 63 / 499,910, filed May 3, 2023. The content of the prior applications is hereby incorporated by reference in its entirety.

[0002]

[0002] This embodiment relates to substrate processing, and more specifically, to an electrostatic chuck for holding a substrate.

Background Art

[0003]

[0003] Substrate holders such as electrostatic chucks are widely used in many manufacturing processes including semiconductor manufacturing, solar cell manufacturing, and the processing of other components. During clamping of a substrate using an electrostatic chuck, excessive charges can accumulate on the substrate. When unloading the substrate from the electrostatic chuck after processing, the existing excessive charges can prevent the declamping of the substrate. Approaches to address substrate charge accumulation include providing a conductive material on the outer surface of the electrostatic chuck, which can be exposed to processing gases and lead to erosion and contamination. The side conductive material also needs to cover the gap region between the metal base and the ceramic, which is formed of silicon or other adhesives and can lead to a non - robust conductive side coating.

[0004]

[0004] This embodiment is provided in view of these considerations and other considerations.

Summary of the Invention

[0005]

[0005] In one embodiment, an electrostatic clamp system is provided. The electrostatic clamp system may include a conductive base and a ceramic body having an inner surface attached to the conductive base and an outer surface facing a substrate. The ceramic body may include an electrode assembly. The electrostatic clamp system may further include a charge control assembly. The charge control assembly may define a conductive structure isolated from the electrode assembly and extending through the conductive base to the upper surface of the outer surface of the ceramic body.

[0006]

[0006] In another embodiment, a processing system is provided. The processing system may include a process chamber and an electrostatic clamping system disposed within the process chamber. The electrostatic clamping system may include a conductive base and a ceramic body having an inner surface attached to the conductive base and an outer surface facing a substrate. The ceramic body may include an electrode assembly. The electrostatic clamping system may further include a charge control assembly, which is isolated from the electrode assembly and defines a conductive structure extending through the conductive base to the upper surface of the outer surface of the ceramic body.

[0007]

[0007] In further embodiments, a method for processing a substrate is provided. This method may include placing the substrate on an electrostatic clamp system. Thus, the electrostatic clamp system may include a conductive base and a ceramic body having an inner surface attached to the conductive base and an outer surface facing the substrate, the ceramic body further including an electrode assembly. The electrostatic clamp system may also include a charge control assembly that defines a conductive structure isolated from the electrode assembly and extending through the conductive base to a surface coating disposed on the upper surface of the outer surface of the ceramic body. This method may also include reversibly electrically connecting the surface coating to external ground or an external voltage source via the charge control assembly. [Brief explanation of the drawing]

[0008] [Figure 1A]

[0008] A side cross-sectional view of an electrostatic clamp system according to an embodiment of the present disclosure is shown. [Figure 1B]

[0009] A side cross-sectional view of another electrostatic clamping system according to an embodiment of the present disclosure is shown. [Figure 2]

[0010] The following are isometric cross-sectional views of electrostatic clamps according to various embodiments of the present disclosure. [Figure 3]

[0011] A top view of another electrostatic clamping system according to an embodiment of the present disclosure is shown. [Figure 4]

[0012] This graph shows the results of radial offset measurements during marathon wafer processing, comparing a known platen arranged according to this embodiment with a standard platen. [Figure 5]

[0013] This graph shows the results of measuring the lift pin drive current during marathon wafer processing, comparing a known platen arranged according to this embodiment with a standard platen. [Figure 6]

[0014] An example processing flow is shown. [Figure 7]

[0015] Another exemplary processing flow is shown. [Figure 8]

[0016] Further illustrative processing flows are shown. [Modes for carrying out the invention]

[0009]

[0017] As detailed in the following figures, in various embodiments, the novel electrostatic clamp system includes a charge control assembly that provides an independent system for removing, adding, or monitoring the charge state of the substrate being processed by the electrostatic clamp.

[0010]

[0018] Figure 1A shows a side cross-sectional view of an electrostatic clamp system 100 according to an embodiment of the present disclosure. The electrostatic clamp system 100 may include a conductive base 102 and a ceramic body 104 having an inner surface 142 attached to the conductive base 102, for example via an epoxy layer 106, and an outer surface 140 facing a substrate, wherein the ceramic body 104 includes an electrode assembly 108. The electrostatic clamp system 100 may be arranged in several embodiments, as with known electrostatic clamps, the conductive base 102 may be a metal such as aluminum, and the ceramic body 104 is a suitable ceramic material that is an electrical insulator or a leaky insulator. The electrode assembly 108 may be embedded within the ceramic body 104, as with known electrostatic clamps, and the electrode assembly 108 may have any suitable configuration and distribution together with the electrostatic clamp. The electrode assembly 108 is connected to an external source and biased to generate an electric field throughout the ceramic body, clamping the substrate to the upper surface 112 of the outer surface 140.

[0011]

[0019] The electrostatic clamp system 100 may further include a charge control assembly 120 that provides an electrical path extending from the top surface 112 to an external component such as external ground or an external voltage source. Specifically, the charge control assembly 120 defines a conductive structure isolated from the electrode assembly 108 and extending through the conductive base 102 to the top surface 112. In this way, the charge control assembly 120 provides a bleed means for charging or adding charge to the substrate 101, contacting the top surface 112, or monitoring the charge state of the substrate 101.

[0012]

[0020] The charge control assembly 120 may be formed from any suitable conductive component or set of components. As further shown in Figure 1A, the charge control assembly 120 may have a portion embedded in the ceramic body 104 and a portion exposed to the outer surface 140. In the embodiment of Figure 1A, the ceramic body 104 includes a seal ring 110 positioned on the outer circumference of the ceramic body 104, the outside of which the seal ring 110 may define the top surface 112. In this embodiment, the ceramic body 104 further includes a gas cooling channel, indicated as a cooling channel 116, positioned inside the seal ring 110. As shown, the charge control assembly 120 extends from within the bulk of the ceramic body 104 into the cooling channel 116, and from the cooling channel 116 to the seal ring 110.

[0013]

[0021] Figure 1B shows a side section view of another electrostatic clamping system, shown as electrostatic clamping system 100B, according to an embodiment of the present disclosure. This system may be similar to electrostatic clamping system 100, and similar components are labeled as such. In this embodiment, a modification of the charge control assembly 120 is shown. The charge control assembly 120 of this modification includes several different components, including conductive pins 134 extending through a conductive base 102 and an embedded layer 132 disposed within the ceramic body 104 and electrically insulated from the conductive base 102 and the electrode assembly 108. The charge control assembly 120 of the embodiment in Figure 1B further includes a surface coating 136, which is connected to the embedded layer 132 and is located on a substrate support structure of the ceramic block, in this case a seal ring 110. According to different non-limiting embodiments, the embedded layer 132 may be a mesh, foil, a layer formed by screen printing, a deposited layer, a set of wires, etc. As shown in Figure 1B, the embedding layer 132 and the surface coating 136 may overlap within the areas of the seal ring 110 and the cooling channel 116.

[0014]

[0022] According to various non-limiting embodiments, the surface coating 136 may be formed from TiN, doped diamond-like carbon, SiC, Y, Ti, Mo, or a combination thereof. According to embodiments of the present disclosure, the surface coating 136 may be formed from any suitable conductive corrosion-resistant material. According to various non-limiting embodiments, the thickness of the surface coating 136 may range from 3 mm to 10 mm. In other embodiments, the thickness of the surface coating 136 may be less than 3 mm or greater than 10 mm, and consideration for an appropriate thickness is the planning period of the surface coating 136. The advantage of positioning the surface coating 136 above the seal ring is that the surface coating provides a contact surface to prevent the substrate from charging at the outer diameter of the substrate 101 and also minimizes the possibility of substrate (wafer) discharge or microarc formation.

[0015]

[0023] Figure 2 shows isometric cross-sectional views of the electrostatic clamp 200 according to various embodiments of the present disclosure. The electrostatic clamp 200 can be considered a modification of the electrostatic clamp system 100B of Figure 1B. Similar components are labeled the same. In this example, the conductive base 102 and the ceramic body 104 form a circular platen, indicated as the platen. As shown in Figure 2, the conductive pins 134 are located inside the seal ring 110, thereby providing an electrical connection from the conductive pins to the surface coating located on the seal ring 110 via an embedded layer 132, which may extend planarly over most of the ceramic body 104 in the XY plane of the illustrated Cartesian coordinate system.

[0016]

[0024] Figure 3 shows a top view of another electrostatic clamp system according to an embodiment of the present disclosure. The electrostatic clamp 300 may be considered a variation of the electrostatic clamp system 100B, and similar components are labeled as such. In this example, the charge control assembly 120 is positioned such that a plurality of conductive segments are located on the outer surface 140 of the ceramic body 104. As previously mentioned, the surface coating 136 is deposited on a region along the outer circumference of the ceramic body 104, such as the seal ring 110, and may extend to the cooling channel 116 located inside the cooling channel 116. In the embodiment of Figure 3, the plurality of conductive segments are shown as conductive segments 302 located on the outer circumference of the ceramic body, i.e., the outer edge, and on the seal ring 110 and a small portion of the cooling channel 116. It should be understood that the figures of various features in the figure are not drawn to scale. Therefore, the diameter of the ceramic body 104 may be, for example, 300 mm or more, while the cooling channel 116 may be located, for example, within 10 mm of the outer edge of the ceramic body 104. Furthermore, according to some non-limiting embodiments, the conductive segment 302 as a whole may occupy only a few degrees of the 360 ​​degrees defined by the ceramic body, for example, an arc of 10 degrees or less. In this way, the area of ​​the conductive segment 302 in contact with the substrate 101 may be relatively small compared to the total substrate tolerance, and may have minimal impact on the operation of the electrostatic clamp 300 during clamping. Alternatively, the embedding layer 132 may be understood to be planarly positioned in the XY plane so as to electrically connect the conductive pins 134 to the conductive segment 302, covering most of the area defined by the ceramic body 104. Thus, only in the position represented by the conductive segment 302, the embedding layer 132 extends from the inside of the ceramic body 104 so as to overlap with the surface coating 136.

[0017]

[0025] In the embodiment of FIG. 3, it should be noted that the conductive segment 302 is arranged as four segments symmetrically arranged around the outer periphery of the ceramic body 104. According to various embodiments of the present disclosure, the charge control assembly 120 may be arranged with only one conductive segment, but in other embodiments, the number of conductive segments 302 is two or more, and the conductive segments 302 are arranged symmetrically. Further, the charge control assembly 120 of the foregoing embodiment is arranged together with a conductive segment arranged towards the outer edge of the ceramic body, such as on the seal ring 110 for example, but in other embodiments, the conductive segments may be arranged towards the center of the ceramic body, such as on the upper surface of an emboss such as the emboss 114 of FIG. 1A or FIG. 1B. In any case, the conductive segment portion of the charge control assembly is arranged to contact the substrate 101 when the substrate 101 is arranged on the ceramic body 104.

[0018]

[0026] In any of the foregoing embodiments, it should be noted that the charge control assembly 120 may be arranged together with the switch 122 such that the conductive segment located on the outer surface of the ceramic body is reversibly connected or separated from an external ground or an external voltage source (not shown separately). In this way, the conductive segment 302 can be grounded or biased at a desired potential in a suitable instance, such as during declamping. Further, in additional embodiments, the charge control assembly may include a monitor connected to the conductive segment to determine the charge state of the electrostatic clamp.

[0019]

[0027] Referring now to FIG. 4, a graph showing the results of radial offset measurements during marathon wafer processing is shown, comparing the known platen of the electrostatic clamp arranged according to this embodiment with the platen of the electrostatic clamp. The radial offset represents a wafer handling parameter of the electrostatic clamp for which a lower radial offset is desired. As shown in FIG. 4, the known electrostatic clamp shows a central radial offset of about 1.0 mm, while the electrostatic clamp arranged with the charge control assembly according to this embodiment shows a much smaller wafer offset of about 0.6 mm.

[0020]

[0028] FIG. 5 is a graph showing the results of measured lift pin drive currents during marathon wafer processing, comparing known platens arranged according to this embodiment with the platens. The lift pin motor current indicates the current required to raise the wafer from contact with the electrostatic chuck. As shown in FIG. 4, the platen of the electrostatic chuck having the charge control assembly of this embodiment requires less current, indicating that there is less wafer adhering to the electrostatic chuck.

[0021]

[0029] FIG. 6 shows an exemplary process flow 600. At block 602, a substrate is placed on an electrostatic chuck system that has a charge control assembly. In one embodiment, the electrostatic chuck system can include a ceramic body having an inner surface attached to a conductive base and an outer surface facing the substrate. The ceramic body can include an electrode assembly used to generate an electric field for the electrostatic chuck. The charge control assembly can define a set of conductive structures or bodies that are isolated from the electrode assembly and extend to a surface coating disposed on the upper surface of the outer surface of the ceramic body through the conductive base. Thus, when the substrate is placed on the electrostatic chuck system, the surface coating can contact the substrate.

[0022]

[0030] At block 604, in a first case, the surface coating is electrically disconnected from an external ground. In one embodiment, a switch can be provided to provide a reversible connection between the surface coating and ground via the charge control assembly. In this way, the switch may be kept in an open position so that the surface coating can float in a first instance, which corresponds to the time when the substrate is clamped to the ceramic body to start substrate processing.

[0023]

[0031] In block 606, in the second instance, the surface coating is electrically connected to external ground via a charge control assembly. In one embodiment, a switch may be provided to provide a reversible connection between the surface coating and ground. Thus, the surface coating can be grounded in the second instance by closing the switch, such as when the second instance corresponds to time for declamping of the substrate.

[0024]

[0032] Figure 7 shows another exemplary processing flow 700. In block 702, a substrate is placed on an electrostatic clamp system, which has a charge control assembly. In one embodiment, the electrostatic clamp system may include a ceramic body having an inner surface that is mounted on a conductive base and an outer surface that faces the substrate. The ceramic body may include an electrode assembly used to generate an electric field for the electrostatic clamp. The charge control assembly may define a set of conductive structures or structures isolated from the electrode assembly and extending through the conductive base to a surface coating placed on the upper surface of the outer surface of the ceramic body. Thus, when the substrate is placed on the electrostatic clamp system, the surface coating may be in contact with the substrate.

[0025]

[0033] In block 704, in the first instance, the surface coating is electrically disconnected from an external voltage source. In one embodiment, a switch may be provided that provides a reversible connection between the surface coating and the external voltage source. In this way, the surface coating can be suspended in the first instance by opening the switch. For example, the first instance corresponds to the time the substrate is clamped to the ceramic body in order to begin substrate processing.

[0026]

[0034] In block 706, in a second instance, the surface coating is electrically connected to an external voltage source via a charge control assembly. In one embodiment, a switch may be provided to provide a reversible connection between the surface coating and the external voltage source. Thus, in the second instance, by closing the switch, the surface coating may be connected to an appropriate potential provided by the external voltage source, such as when the second instance corresponds to a time for declamming the substrate.

[0027]

[0035] Figure 8 shows another exemplary processing flow 800. In block 802, a substrate is placed on an electrostatic clamp system, which has a charge control assembly. In one embodiment, the electrostatic clamp system may include a ceramic body having an inner surface that is mounted on a conductive base and an outer surface that faces the substrate. The ceramic body may include an electrode assembly used to generate an electric field for the electrostatic clamp. The charge control assembly may define a set of conductive structures or structures isolated from the electrode assembly and extending through the conductive base to a surface coating placed on the upper surface of the outer surface of the ceramic body. Thus, when the substrate is placed on the electrostatic clamp system, the surface coating may come into contact with the substrate.

[0028]

[0036] In block 804, the substrate is processed while clamped in an electrostatic clamping system. In one embodiment, a switch may be provided that provides a reversible connection between the surface coating and an external voltage source. In this way, by opening the switch, the surface coating can be suspended during substrate processing.

[0029]

[0037] In block 806, the surface coating is electrically connected to an external monitor. In this way, the charge state of the surface coating can be probed. For example, to examine the charge accumulation on the surface coating after the processing period, the switch may be closed after the substrate processing period so that the surface coating is electrically connected to the external monitor via a charge control assembly. The electrical connection to the external monitor may be made while the substrate is being processed or after the processing has stopped, according to different embodiments.

[0030]

[0038] In short, this embodiment provides a novel approach to controlling charge on a substrate positioned on an electrostatic clamp, offering the advantages of assisting in declamping the substrate by reducing substrate adhesion and improving substrate positioning. Furthermore, this embodiment helps to avoid substrate discharge or microarcs, thereby reducing particle generation and yield loss.

[0031]

[0039] This disclosure should not be limited in scope by the specific embodiments described herein. In fact, a person skilled in the art will see from the above description and accompanying drawings a variety of embodiments and modifications other than those described herein, in addition to the embodiments and modifications to this disclosure. Thus, such other embodiments and modifications are intended to be included within the scope of this disclosure. Furthermore, while this disclosure has been described herein in relation to a specific implementation in a specific environment for a specific purpose, a person skilled in the art will recognize that the usefulness of this disclosure is not limited thereto, and that this disclosure can be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims of this application should be interpreted in the broadest possible view of the scope and spirit of this disclosure as described herein.

Claims

1. An electrostatic clamping system, A conductive base, A ceramic body having an inner surface that is attached to the conductive base and an outer surface that faces the substrate, the ceramic body including an electrode assembly, A charge control assembly defining a conductive structure, wherein the conductive structure is isolated from the electrode assembly and extends through the conductive base to the upper surface of the outer surface of the ceramic body, An electrostatic clamping system equipped with the following features.

2. The charge control assembly, A conductive pin extending through the conductive base, An embedded layer, disposed within the ceramic body and electrically insulated from the conductive base and the electrode assembly, A surface coating connected to the aforementioned embedding layer and positioned on the substrate support structure of the ceramic body, The electrostatic clamping system according to claim 1, further comprising the following:

3. The electrostatic clamping system according to claim 2, wherein the embedding layer includes a mesh, foil, screen printing, or a deposited layer.

4. The electrostatic clamping system according to claim 2, wherein the surface coating is arranged within a plurality of conductive segments, and the plurality of conductive segments are arranged to contact a substrate when placed on the ceramic body.

5. The electrostatic clamping system according to claim 4, wherein the plurality of conductive segments include two or more conductive segments arranged symmetrically along the outer edge of the ceramic body.

6. The electrostatic clamping system according to claim 4, wherein the plurality of conductive segments occupy less than 10 degrees of the arc along the outer circumference of the ceramic body.

7. The aforementioned ceramic body, A seal ring arranged along the outer circumference of the conductive coating, the seal ring defining the upper surface of the outer surface of the ceramic body, The seal ring further comprises a gas cooling channel located inside the seal ring, The surface coating extends continuously over the seal ring and the gas cooling channel. The electrostatic clamping system according to claim 2, wherein the embedding layer extends at least into the gas cooling channel.

8. The charge control assembly is electrically insulated from the conductive base, The electrostatic clamp system according to claim 1, wherein the charge control assembly further comprises a switch, the switch being configured to reversibly connect or disconnect the conductive structure from external ground or an external voltage source.

9. The electrostatic clamping system according to claim 2, wherein the surface coating comprises TiN, doped diamond-like carbon, SiC, Y, Ti, or Mo.

10. The electrostatic clamp system according to claim 1, wherein the charge control assembly further comprises a monitor connected to the conductive structure for determining the charge state of the electrostatic clamp.

11. A processing system, process chamber and An electrostatic clamping system arranged within the process chamber, The electrostatic clamp system is equipped with, A conductive base, A ceramic body having an inner surface that is attached to the conductive base and an outer surface that faces the substrate, the ceramic body including an electrode assembly, A charge control assembly defining a conductive structure, wherein the conductive structure is isolated from the electrode assembly and extends through the conductive base to the upper surface of the outer surface of the ceramic body, Processing system.

12. The charge control assembly, A conductive pin extending through the conductive base, An embedded layer, disposed within the ceramic body and electrically insulated from the conductive base and the electrode assembly, A surface coating connected to the aforementioned embedding layer and positioned on the substrate support structure of the ceramic body, The processing system according to claim 11, comprising:

13. The processing system according to claim 12, wherein the embedding layer includes a mesh, foil, screen printing, or a deposited layer.

14. The processing system according to claim 12, wherein the surface coating is arranged within a plurality of conductive segments, and the plurality of conductive segments are arranged to contact a substrate when placed on the ceramic body.

15. The processing system according to claim 14, wherein the plurality of conductive segments include two or more conductive segments arranged symmetrically along the outer edge of the ceramic body.

16. The processing system according to claim 14, wherein the plurality of conductive segments occupy less than 10 degrees of the arc along the outer edge of the ceramic body.

17. The aforementioned ceramic body, A seal ring arranged along the outer circumference of the conductive coating, the seal ring defining the upper surface of the outer surface of the ceramic body, The seal ring further comprises a gas cooling channel located inside the seal ring, The surface coating extends continuously over the seal ring and the gas cooling channel. The processing system according to claim 12, wherein the embedding layer extends at least into the gas cooling channel.

18. The charge control assembly is electrically insulated from the conductive base, The processing system according to claim 11, wherein the charge control assembly further comprises a switch, the switch being configured to reversibly connect or disconnect the conductive structure from external ground or an external voltage source.

19. A method for processing a substrate, Placing the substrate on an electrostatic clamp system, wherein the electrostatic clamp system A conductive base, A ceramic body having an inner surface that is attached to the conductive base and an outer surface that faces the substrate, the ceramic body including an electrode assembly, A charge control assembly defining a conductive structure, wherein the conductive structure is isolated from the electrode assembly and extends through the conductive base to a surface coating disposed on the upper surface of the outer surface of the ceramic body, and the substrate is arranged thereon. The surface coating is reversibly and electrically connected to external ground or an external voltage source via a charge control assembly. Methods that include...

20. Processing the substrate while it is clamped in the electrostatic clamping system, The surface coating is electrically connected to an external monitor to monitor the charge state of the surface coating after or during the process, The method according to claim 19, further comprising:

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