Apparatus and Method for Reducing Polymer Deposition

Abstract

The present invention relates to an apparatus and method for reducing polymer deposition. Implementations of the present disclosure provide a process fitting for an electrostatic chuck. In one implementation, a substrate support assembly is provided. The substrate support assembly includes an electrostatic chuck having a first recess formed in an upper portion of the electrostatic chuck. The process fitting surrounds the electrostatic chuck. The process fitting includes an inner ring and an outer ring disposed radially outside the inner ring. The outer ring includes a second recess formed in an upper portion of the upper ring. The inner ring is positioned within and supported by the first recess and the second recess. The upper surface of the inner ring and the upper surface of the outer ring are coplanar.

Description

Technical Field

[0001] Examples of the present disclosure generally relate to devices for processing substrates, such as semiconductor substrates. More specifically, a process fitting for an electrostatic chuck is disclosed. Background Art

[0002] In the processing of substrates such as semiconductor substrates and display panels, the substrate is placed on a substrate support in a process chamber while maintaining suitable process conditions in the process chamber to deposit, etch, form layers, or otherwise process the surface of the substrate. During an etching process, the plasma driving the etching process may be unevenly distributed over the surface of the substrate. The non-uniformity is particularly evident at the edges of the substrate surface. Such non-uniformity results in poor processing results. Therefore, some process chambers use an edge ring (the edge ring may also be referred to as a process fitting ring) to improve plasma uniformity and process yield.

[0003] However, it has been observed that the etching process may cause polymer materials to accumulate at the edges of the substrate surface. The polymer materials may get stuck in the gap between the edge of the substrate and the process fitting ring and spread to the electrostatic chuck of the substrate support. When the substrate is lifted and / or the plasma is turned off, the polymer materials may be deposited back onto the substrate surface, thereby adversely affecting substrate processing.

[0004] Therefore, there is a need in the art for a device that can solve the problems discussed above. Summary of the Invention

[0005] In one implementation, a substrate support assembly is provided. The substrate support assembly includes an electrostatic chuck having a first recess formed in an upper portion of the electrostatic chuck. A process fitting surrounds the electrostatic chuck. The process fitting includes an inner ring and an outer ring disposed radially outside the inner ring. The outer ring includes a second recess formed in an upper portion of the outer ring. The inner ring is positioned within and supported by the first recess and the second recess. An upper surface of the inner ring and an upper surface of the outer ring are coplanar.

[0006] In another implementation, a substrate support assembly for processing a substrate is provided. The substrate support assembly includes a substrate support and an electrostatic chuck disposed on the substrate support. The electrostatic chuck includes a first recess formed in an upper portion of the electrostatic chuck. A process fitting surrounds the electrostatic chuck. The process fitting includes an inner ring and an outer ring disposed radially outside the inner ring. The outer ring includes a second recess formed in an upper portion of the outer ring. The inner ring is positioned within and supported by the first recess and the second recess. An upper surface of the outer ring is higher than an upper surface of the inner ring. A plurality of pumping channels are formed through the outer ring. The pumping channels are angled downwardly in a direction away from the inner ring.

[0007] In yet another implementation, a method of removing particles from a substrate support surface includes disposing a top surface of an outer ring coplanarly with a top surface of an inner ring. The outer ring is disposed radially outside the inner ring. The outer ring includes a first upper surface and a second upper surface. The first upper surface is coplanar with the upper surface of the inner ring. A plurality of protrusions are symmetrically disposed on the inner ring. The plurality of protrusions are configured to position a substrate on the substrate support surface. Pumping channels are disposed on the outer ring. The pumping channels are configured to pump unwanted material away from the substrate support. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] To enable a manner of understanding the above-described features of the present disclosure in detail, a more particular description of the present disclosure, briefly summarized above, may be had by reference to aspects of the present disclosure, some of which are illustrated in the drawings. It should be noted, however, that the drawings illustrate only typical aspects of the present disclosure and are therefore not to be considered limiting of the scope of the present disclosure, as the present disclosure may admit other equivalent aspects.

[0009] Figure 1 is a schematic cross-sectional view of a process chamber according to an example of the present disclosure.

[0010] Figure 2 is an enlarged schematic view of a substrate support assembly of a process chamber according to an example described herein.

[0011] Figure 3 shows a simplified perspective view of an inner ring, which shows the protrusions.

[0012] Figure 4A shows a cross-sectional view of a process fitting according to one implementation.

[0013] Figure 4B shows a perspective view of a pumping ring, which shows the protrusions.

[0014] Figure 5 shows a cross-sectional view of a process fitting according to one implementation.

[0015] Figure 6A A cross-sectional view of a process fitting according to one implementation is shown.

[0016] Figure 6B A perspective view of a portion of the process fitting is shown, which shows a pumping channel.

[0017] Figure 7 It is a flowchart of an exemplary method for removing contaminants from the surface of a substrate support.

[0018] For ease of understanding, the same reference numerals have been used to label the same elements common to the figures as much as possible. Additionally, elements in one example can be advantageously adapted for use in other examples described herein. Detailed Description

[0019] Implementations of the present disclosure provide a process fitting for a substrate support assembly, the substrate support assembly including an electrostatic chuck disposed on the top surface of a substrate support. The process fitting surrounds the electrostatic chuck and includes an inner ring and an outer ring concentrically positioned relative to the substrate support. The upper surfaces of the inner ring and the outer ring can be coplanar or at different heights, and the outer ring can include a pumping channel to help discharge unwanted polymer material from the edges of the process fitting and the electrostatic chuck, thereby improving substrate quality and process yield.

[0020] Figure 1 It is a schematic cross-sectional view of a process chamber 100 according to an example of the present disclosure. The illustrated process chamber 100 is adapted for etching, chemical vapor deposition (CVD), or other plasma-based processes. The process chamber 100 includes a chamber body 101 and a lid 103 disposed on the chamber body 101. The chamber body 101 and the lid 103 together define an internal volume. The chamber body 101 is typically coupled to an electrical ground 107. A substrate support assembly 111 is disposed within the internal volume to support a substrate 109 on the substrate support assembly 111 during processing. The process chamber 100 further includes an inductively coupled plasma device 102 for generating plasma within the process chamber 100, and a controller 155 adapted to control the operation of the process chamber 100.

[0021] The substrate support assembly 111 includes one or more electrodes 153 that are coupled to a bias source 119 via a matching network 120 to bias the substrate 109 during processing. The bias source 119 can be a source of RF energy up to about 1000 W (but not limited to about 1000 W) at a frequency of, for example, about 13.56 MHz, but other frequencies and powers can be provided as needed for specific applications. The bias source 119 can be capable of generating either or both continuous or pulsed power. In some examples, the bias source 119 can be a DC or pulsed DC source. In some examples, the bias source 119 can be capable of providing multiple frequencies. One or more electrodes 153 can be coupled to a clamping power supply 160 to clamp the substrate 109 during processing. The substrate support assembly 111 includes a process fitting (not shown) that surrounds the substrate 109. Various implementations of the process fitting will be described in more detail below.

[0022] The inductively coupled plasma device 102 is disposed above the lid 103 and configured to inductively couple RF power into the process chamber 100 to generate a plasma within the process chamber 100. The inductively coupled plasma device 102 includes a first coil 110 and a second coil 112 disposed above the lid 103. The relative positions, diameter ratios, and / or number of turns in each of the coils 110, 112 can each be selected as needed to control the profile or density of the plasma being formed. Each of the first coil 110 and the second coil 112 is coupled to an RF power supply 108 via an RF feed structure 106 through a matching network 114. The RF power supply 108 can be capable of generating up to about 4000 W (but not limited to 4000 W) at a tunable frequency within the range from 50 kHz to 13.56 MHz, but other frequencies and powers can be utilized as needed for specific applications.

[0023] In some examples, a power divider 105 (such as a voltage dividing capacitor) can be provided between the RF feed structure 106 and the RF power supply 108 to control the relative amounts of RF power provided to the respective first and second coils. In some examples, the power divider 105 can be incorporated into the matching network 114.

[0024] A heater element 113 can be disposed on top of the lid 103 to facilitate heating the interior of the process chamber 100. The heater element 113 can be disposed between the lid 103 and the first coil 110 and the second coil 112. In some examples, the heater element 113 can include a resistive heating element and can be coupled to a power supply 115 (such as an AC power supply) configured to provide sufficient energy to control the temperature of the heater element 113 within a desired range.

[0025] During operation, a substrate 109, such as a semiconductor wafer or other substrate suitable for plasma processing, is placed on a substrate support assembly 111, and process gas is supplied from a gas panel 116 into the interior volume of the chamber body 101 through an inlet port 117. Additionally or alternatively, process gas can be supplied into the interior volume of the chamber body 101 through an inlet port (not shown) provided in the lid 103. In either case, by applying power from an RF power supply 108 to the first coil 110 and the second coil 112, the process gas is ignited into a plasma 118 within the process chamber 100. In some examples, power from a bias source 119, such as an RF or DC source, can also be provided to an electrode 153 within the substrate support assembly 111 through a matching network 120. The pressure within the interior of the process chamber 100 can be controlled using a valve 121 and a vacuum pump 122. The temperature of the chamber body 101 can be controlled using a conduit (not shown) that extends through the chamber body 101 and contains a liquid.

[0026] A controller 155 is configured to control the operation of the process chamber 100 during processing. The controller 155 includes a central processing unit (CPU) 123, a memory 124, and support circuitry 125 for the CPU 123, and facilitates the control of the components of the process chamber 100. The controller 155 can be one of any form of general computer processor that can be used in an industrial environment to control various chambers and sub-processors. The memory 124 stores software (source or object code) that can be executed or invoked to control the operation of the process chamber 100 in the manner described herein.

[0027] Figure 2 is an enlarged schematic view of a substrate support assembly 111 of a process chamber 100 according to one example described herein. The substrate support assembly 111 includes a process fitting 203, a substrate support 205, and an electrostatic chuck 229. The electrostatic chuck 229 is disposed on the top surface of the substrate support 205 and is surrounded by the process fitting 203. The substrate support 205 includes a ground plate 226 that surrounds an insulating plate 227 and facility plates 228 assembled into a vertical stack. The substrate support 205 also includes a sleeve 230 that surrounds the facility plates 228 and the electrostatic chuck 229 to insulate the RF thermal electrostatic chuck 229 from the ground plate 226. The sleeve 230 can be made of quartz.

[0028] The facility plates 228 are positioned above the lower portion of the ground plate 226 and between the insulating plate 227 and the electrostatic chuck 229. The electrostatic chuck 229 can include a plurality of electrodes 153 (four electrodes are shown) embedded in an insulating material 236. The electrodes 153 are coupled to a clamping power supply 160 as Figure 1as shown) to facilitate pulling the substrate 109 tightly against the upper surface 233 of the electrostatic chuck 229. One or more heating or cooling channels may optionally be formed in the insulating material 236 to facilitate temperature control of the substrate 109 during processing. In some aspects, the electrode 153 is coupled to a bias source 119 (such as Figure 1 as shown) at the cathode.

[0029] The process fitting 203 includes a cover ring 246, an inner ring 242, and an outer ring 244, which are arranged concentrically with respect to an axis passing through the center of the substrate support assembly 111. In some examples, the cover ring 246 is optional and may not be necessary. In the case of using the cover ring 246, the cover ring 246 may be positioned on the upper surface 241 of the outer ring 244. The cover ring 246 surrounds the radially outer edge of the substrate 109. In some examples, the cover ring 246 is sized to abut the edge of the substrate 109. The cover ring 246 helps protect the edge of the substrate 109 during processing and, additionally, provides lateral support to the substrate 109 during processing. The cover ring 246 may be made of quartz, silicon, or any other plasma-resistant material. The inner ring 242 may be made of silicon or any other plasma-resistant material. In a particular example, the inner ring 242 is made of silicon carbide (SiC). The outer ring 244 may be made of quartz, silicon, or any other plasma-resistant material. In one example, the inner ring 242 is made of silicon and the outer ring 244 is made of quartz.

[0030] The outer ring 244 is disposed radially outside the inner ring 242. The outer ring 244 is positioned on the upper surface of the vertical edge of the ground plate 226. The outer ring 244 includes a bottom recess 231 formed in the bottom surface of the outer ring 244 for engaging the sleeve 230. The outer ring 244 may further include an upper recess 249 formed in the upper surface 241 of the outer ring 244 to facilitate positioning of the cover ring 246. Although the substrate 109 is shown as having a radially outer edge extending above the upper surface 245 of the inner ring 242, it is contemplated that the radially outer edge and the upper surface 245 of the substrate 109 may not overlap. That is, the radially outer edge of the substrate 109 may stop at the edge of the upper portion of the electrostatic chuck 229.

[0031] The inner ring 242 is supported jointly by the electrostatic chuck 229 and the outer ring 244. The inner ring 242 is positioned such that the upper surface 245 of the inner ring 242 and the upper surface 241 of the outer ring 244 are coplanar. For example, a portion of the inner ring 242 is positioned within the recess 235 of the electrostatic chuck 229 and is supported by the recess 235. The recess 235 may be formed in the outer periphery of the upper portion of the electrostatic chuck 229. The remaining portion of the inner ring 242 is positioned within the recess 237 of the outer ring 244 and is supported by the recess 237. The recess 237 may be formed in the inner periphery of the upper portion of the outer ring 244. The top surface of the recess 235 and the top surface of the recess 237 are at the same height.

[0032] The upper surface 245 of the inner ring 242 and the upper surface 241 of the outer ring 244 are coplanar, or at the same height, to facilitate pumping of unwanted polymeric material (accumulated between the process fitting 203 and the edge of the electrostatic chuck 229) to the vacuum pump 122 (see Figure 1 ). The inner ring 242 may be stationary relative to the substrate 109 during processing.

[0033] The radially outer edge of the inner ring 242 may be spaced from the vertical wall of the recess 237 by a gap "D1" to allow for thermal expansion of the inner ring 242 and / or the outer ring 244. The gap "D1" may range from about 0.002 inches to about 0.030 inches, such as from about 0.010 inches to about 0.020 inches, and may vary depending on the materials used for the inner ring 242 and the outer ring 244. The size of the gap "D1" may be selected to prevent deposition of polymeric material at the radially outer edge of the inner ring 242. In some examples, the radially outer edge of the inner ring 242 contacts the vertical wall of the recess 237.

[0034] The outer ring 244 is positioned concentrically relative to the inner ring 242 and the substrate 109. The outer ring 244 assists the inner ring 242 in providing lateral support to the substrate 109 and reducing undesired etching of the inner ring 242. In some examples, the upper surface 245 of the inner ring 242 may be provided with a plurality of protrusions 243 (only one is shown) to prevent the substrate 109 from sliding during processing. Figure 3 A simplified perspective view of the inner ring 242 and the outer ring 244 is shown, which shows three protrusions 243 symmetrically disposed around the circumference of the inner ring 242 to restrain movement of the substrate 109. It is contemplated that any number of protrusions 243 may be used. The protrusions 243 may be spherical caps, cylinders, raised dots, or have any other suitable geometry. The protrusions 243 may be made of the same or different material as the inner ring 242. In one example, the protrusions 243 are made of silicon carbide.

[0035] The substrate support assembly 111 may optionally include one or more actuators 247, such as a stepper motor or a linear actuator, etc. For example, one or more actuators 247 are disposed in the ground plate 226. However, it is contemplated that the actuators 247 may be positioned outside the substrate support assembly 111. Each actuator 247 is adapted to engage or interface with one or more push pins 248. One or more push pins 248 extend from the ground plate 226 through the insulating plate 227 and the sleeve 230 and contact the outer ring 244. Actuation of one or more push pins 248 causes the outer ring 244, the inner ring 242, and the cover ring 246 (if used) to be actuated or displaced vertically relative to the upper surface of the substrate 109. The position of the outer ring 244 can be adjusted to accommodate the eroded height of the outer ring 244 so as to improve plasma uniformity across the substrate surface during processing.

[0036] The substrate support assembly 111 further includes three or more lift rods 288 for lifting the substrate 109 away from the surface of the electrostatic chuck 229. The lift rods 288 extend from the ground plate 226, the insulating plate 227, the facility plate 228 and pass through the electrostatic chuck 229 to corresponding lift rod holes 286( Figure 3 ). The lift rods 288 are controlled by actuators 284. Each actuator 284 is adapted to engage or interface with the lift rod 288 to move the lift rod 288 upward and / or downward.

[0037] One or more bellows may be positioned around each of the one or more push pins 248 to reduce particulate contamination within the process chamber 100 (as Figure 1 shown). Additionally, one or more push pin guides 239 (such as guide sleeves or bearings) may be positioned within the sleeve 230 disposed around each push pin 248 to facilitate actuation of each push pin 248. The push pin guides 239 provide a support surface for the push pins 248. Actuation of the push pins 248 may be operably controlled by a controller 155 (as Figure 1 shown).

[0038] In one example, one or more actuators 247 are micro stepper motors. In another example, one or more actuators 247 are piezoelectric motors. In one example, one or more push pins 248 are made of quartz or sapphire.

[0039] In one example, the controller may be a general-purpose computer that includes a memory for storing software. The software may include for detecting corrosion of the inner ring 242 and the outer ring 244 and then instructing one or more actuators 247 to raise one or more push pins 248 such that the inner ring 242 and the outer ring 244 are raised to a desired height.

[0040] Figure 4AA cross-sectional view of a process fitting 400 according to one implementation is shown. The process fitting 400 can be used in place of Figure 2 process fitting 203. The process fitting 400 includes an inner ring 442, an outer ring 444, and a pumping ring 446. The outer ring 444 is disposed radially outside the inner ring 442. The inner ring 442 and the outer ring 444 are similar in design to the inner ring 242 and the outer ring 244, except that the entire upper surface 441 of the outer ring 444 and the entire upper surface 445 of the inner ring 442 are coplanar, or at the same height.

[0041] The pumping ring 446 is disposed above the outer ring 444. The pumping ring 446 can have three or more protrusions 448 disposed at the bottom surface of the pumping ring 446. The protrusions 448 create a gap "D2" between the outer ring 444 and the pumping ring 446 to allow unwanted polymeric material (accumulated between the process fitting 400 and the edge of the electrostatic chuck 229) to pass through, and the unwanted polymeric material is then pumped out of the process chamber by a vacuum pump 122 ( Figure 1 ). The protrusions 448 can be symmetrically arranged around the circumference of the pumping ring 446. Figure 4B A perspective view of the pumping ring 446 is shown, which shows six protrusions 448 disposed at the bottom surface 450 of the pumping ring 446. Any number of protrusions can be used to obtain the desired and / or maximum pumping area.

[0042] The gap "D2" can be in the range of about 0.002 inches to about 0.1 inches, such as about 0.010 inches to about 0.050 inches. In an alternative implementation, for the same purpose, protrusions 448 can be provided at the upper surface 441 of the outer ring 444 to create the gap "D2". In either case, the size of the gap "D2" can be selected to change the pumping efficiency. The pumping ring 446 can be made of quartz, silicon, or any other plasma-resistant material. The inner ring 442 and the outer ring 444 can be made of the same materials as the inner ring 242 and the outer ring 244 discussed above.

[0043] Figure 5A cross-sectional view of a process fitting 500 according to one implementation is shown. The process fitting 500 includes an inner ring 542 and an outer ring 544 disposed radially outside the inner ring 542. In this implementation, the inner ring 542 and the outer ring 544 are similar in design to the inner ring 242 and the outer ring 244, except that the outer ring 544 has a first upper surface 541 and a second upper surface 543. The first upper surface 541 is coplanar with the upper surface 545 of the inner ring 542. The second upper surface 543 has a slope in a direction away from the inner ring 542. In some examples, the entire upper surface of the outer ring 544 can be a ramp. The longitudinal axis of the second upper surface 543 can be angled “α” with respect to the direction extending along the outer peripheral surface 547 of the outer ring 544. In one implementation, the angle “α” is in the range of about 35 degrees to about 85 degrees, such as about 45 degrees to about 75 degrees, for example about 60 degrees. Compared with an outer ring having an entire planar upper surface (e.g., process fitting 400), the slope of the second upper surface 543 allows unwanted polymeric material (accumulated between the process fitting 500 and the edge of the electrostatic chuck 229) to be pumped more effectively to the vacuum pump 122.

[0044] Figure 6A A cross-sectional view of a process fitting 600 according to one implementation is shown. The process fitting 600 includes an inner ring 642 and an outer ring 644 disposed radially outside the inner ring 642. A plurality of protrusions 643 are provided at the upper surface 645 of the inner ring 642. Similar to the protrusions 243, the protrusions 643 can assist in the positioning of a substrate (not shown) during the process. The process fitting 600 can optionally include a cover ring 646 positioned on the upper surface 641 of the outer ring 644. The inner ring 642, the outer ring 644, and the cover ring 646 (if used) are similar in design to the inner ring 242, the outer ring 244, and the cover ring 246, except that the upper surface 641 of the outer ring 644 is higher than the upper surface 645 of the inner ring 642 by a distance “D3”. In one implementation, the distance “D3” can be in the range of about 0.01 inches to about 5 inches, such as about 0.1 inches to about 2 inches, for example about 1 inch.

[0045] In one implementation that may be included in or combined with any other implementation discussed in the present disclosure, the outer ring 644 further includes a plurality of pumping channels 647 formed through the outer ring 644. The pumping channels 647 may extend from the vertical wall 639 of the recess 637 formed in the inner circumference of the upper portion of the outer ring 644 to the outer peripheral surface 653 of the outer ring 644. The pumping channels 647 may be angled downward in a direction away from the inner ring 642. For example, the longitudinal direction of the pumping channels 647 may be angled at an angle "β" with respect to the direction extending along the outer peripheral surface 653. In one implementation, the angle "β" is in the range of about 30 degrees to about 88 degrees, such as about 40 degrees to about 65 degrees, for example about 50 degrees. Unwanted polymeric materials or particles that accumulate between the process fitting 600 and the edge of the electrostatic chuck 229 may be pumped through the pumping channels 647 to the vacuum pump 122( Figure 1 ).

[0046] Figure 6B A perspective view of a portion of the process fitting 600 is shown, which shows the pumping channels 647 formed in the vertical wall 639 located in the upper portion of the outer ring 644. The pumping channels 647 may be symmetrically disposed around the circumference of the outer ring 644. The pumping channels 647 may have any suitable shape, such as circular, square, triangular, etc. The diameter of the pumping channels 647 may be in the range of about 0.1 inches to about 1 inch.

[0047] Implementations of the present disclosure result in an improvement in the quality of the substrate being processed in the process chamber because unwanted polymeric materials that accumulate at the edges of the process fitting and the electrostatic chuck can be more effectively discharged through the pumping channels formed in the outer ring of the process fitting. The improvement in substrate quality results in an improvement in process yield. In addition, the process chamber utilizing the present disclosure reduces downtime for preventive maintenance by extending the service life of the process fitting.

[0048] Figure 7 is a flowchart of an exemplary method 700 for removing contaminants from the surface of a substrate support (i.e., the electrostatic chuck 229).

[0049] At block 704, a plurality of protrusions 243 are symmetrically arranged on the upper surface 245 of the inner ring 242. As Figure 2 and Figure 3As shown, protrusions 243 are symmetrically disposed around the circumference of the inner ring 242 to restrict the movement of the substrate 109. At block 708, the upper surface 241 of the outer ring 244 is disposed coplanarly with the upper surface 245 of the inner ring 242. As previously described, by disposing the upper surface 245 of the inner ring 242 coplanarly with the upper surface 241 of the outer ring 244, it facilitates pumping of unwanted polymeric material. In one configuration shown along path 701, the gap D2 (i.e., the channel) can be oriented in the horizontal direction to facilitate pumping of unwanted material, as shown in FIG. 4. At block 712, a channel 647 is provided through the outer ring 644. As shown along path 703, the channel 647 is configured to pump away unwanted material from a substrate support (e.g., the electrostatic chuck 229). As previously described, the channel 647 is also configured to pump away unwanted material from the process fitting 203. In Figures 6A to 6B the example shown, the channel 647 has a circular or oval cross-sectional area. In another example, the channel has a square or rectangular cross-sectional area (not shown). At block 716, the channel 647 is positioned at an acute angle “β” away from the inner ring 642. A portion of the channel 647 can be positioned beneath the substrate 109. The substrate 109 is positioned on the upper surface 233 of the electrostatic chuck 229. The upper surface 233 is substantially coplanar with the upper surface 245 of the inner ring 242. As previously described, the angle “β” is taken with respect to the direction extending along the outer peripheral surface 653. Path 705 shows another example including block 720. At block 720, a bevel surface 543 is provided on the outer ring 244 below the first upper surface 541 of the outer ring 544 at an acute angle “α”, as Figure 5 shown. At block 724, a cover ring 246 is disposed above the outer ring 244. At block 728, a gap D2 is formed between the upper surface 241 of the outer ring 244 and the bottom surface of the pumping ring 446. As previously described, the gap D2 (i.e., the channel) allows unwanted polymeric material to be conveyed away from the substrate support and the process fitting 400. As shown in FIG. 4, in at least one example, protrusions 448 can be symmetrically disposed around the circumference of the pumping ring 446 (e.g., the outer ring 244), thereby creating the gap D2.

[0050] Although the foregoing is directed to implementations of the present disclosure, other and further implementations of the present disclosure can be envisioned without departing from the basic scope of the present disclosure.

Claims

1. A substrate support assembly comprising: an electrostatic chuck comprising a first recess formed in an upper portion of the electrostatic chuck; as well as A process accessory, the process accessory surrounding the electrostatic chuck, wherein the process accessory comprises: inner ring; an outer ring disposed radially outward of the inner ring, wherein the outer ring includes a second recess formed in an upper portion of the outer ring, and the inner ring is positioned within and supported by the first and second recesses such that an upper surface of the inner ring and an upper surface of the outer ring are coplanar; and A pumping channel on the outer ring is configured to pump unwanted material away from the substrate support.

2. The substrate support assembly of claim 1, wherein the inner ring is made of silicon.

3. The substrate support assembly of claim 1, wherein the outer ring is made of quartz. 4 . The substrate support assembly of claim 1 , wherein the upper surface of the inner ring has a plurality of protrusions symmetrically arranged around a circumference of the inner ring.

5. The substrate support assembly of claim 1 , further comprising: A pumping ring is disposed above the outer ring. 6 . The substrate support assembly of claim 5 , wherein the pumping ring has a plurality of protrusions disposed at a bottom surface of the pumping ring. 7 . The substrate support assembly of claim 1 , wherein a top surface of the first recess and a top surface of the second recess are at the same height.

8. A substrate support assembly for processing a substrate, the substrate support assembly comprising: a substrate support; an electrostatic chuck disposed on the substrate support, wherein the electrostatic chuck includes a first recess formed in an upper portion of the electrostatic chuck; as well as A process accessory, the process accessory surrounding the electrostatic chuck, wherein the process accessory comprises: inner ring; an outer ring disposed radially outside the inner ring, wherein the outer ring includes a second recess formed in an upper portion of the outer ring, wherein the inner ring is positioned within and supported by the first and second recesses, and an upper surface of the outer ring is higher than an upper surface of the inner ring, and the outer ring includes an upper recess formed in an upper surface of the outer ring; and A plurality of pumping channels are formed through the outer ring, wherein the pumping channels are angled downwardly away from the inner ring and are configured to pump unwanted material away from the substrate support.

9. The substrate support assembly of claim 8, wherein the inner ring is made of silicon.

10. The substrate support assembly of claim 8, wherein the outer ring is made of quartz.

11. The substrate support assembly of claim 8, wherein the upper surface of the inner ring has a plurality of protrusions, the plurality of protrusions being symmetrically arranged around a circumference of the inner ring.

12. The substrate support assembly of claim 8, wherein a longitudinal direction of the pumping channel is angled relative to a direction extending along the outer peripheral surface of the outer ring.

13. The substrate support assembly of claim 12, wherein the angle is in the range of 30 degrees to 88 degrees.

14. The substrate support assembly of claim 8, further comprising: A cover ring is arranged above the outer ring.

15. The substrate support assembly of claim 14, wherein the cover ring is made of quartz or silicon.

16. A method of removing particles from a substrate support surface, comprising: Arranging a top surface of an outer ring coplanar with a top surface of an inner ring, wherein the outer ring is disposed radially outward of the inner ring, the outer ring comprising a first upper surface and a second upper surface, wherein the first upper surface is coplanar with the upper surface of the inner ring; a plurality of protrusions symmetrically arranged on the inner ring for positioning a substrate on the substrate support surface; A pumping channel is provided on the outer ring, the pumping channel being configured to pump unwanted material away from the substrate support.

17. The method of claim 16, further comprising: A portion of each pumping channel is positioned at an acute angle below the bottom surface of the substrate.

18. The method of claim 16, further comprising: An inclined surface is provided in the outer ring at an acute angle below the top surface of the outer ring.

19. The method of claim 16, wherein the pumping passage is provided through a surface of the outer ring.

20. The method of claim 16, further comprising: A cover ring is arranged above the outer ring.

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