Azimuthal edge ring control to improve residual non-uniformity near substrate edges

Abstract

A substrate processing system includes a substrate support, an edge ring arranged around the substrate support, a plurality of lift pins configured to move the edge ring, and a plurality of actuators coupled to the plurality of lift pins, respectively, the plurality of actuators configured to move the plurality of lift pins independently of each other.

Description

AZIMUTHAL EDGE RING CONTROL TO IMPROVE RESIDUAL NON-UNIFORMITY NEAR SUBSTRATE EDGESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 605,807 filed on December 4, 2023. The entire disclosure of the above application is incorporated herein by reference.FIELD

[0002] The present disclosure relates generally to substrate processing systems and more particularly to azimuthal edge ring control to improve residual non-uniformity near substrate edges.BACKGROUND

[0003] The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

[0004] A substrate processing system typically includes a plurality of processing chambers (also called process modules) to perform deposition, etching, and other treatments of substrates such as semiconductor wafers. Examples of processes that may be performed on a substrate include, but are not limited to, plasma enhanced chemical vapor deposition (PECVD), chemically enhanced plasma vapor deposition (CEPVD), sputtering physical vapor deposition (PVD), atomic layer deposition (ALD), and plasma enhanced ALD (PEALD). Additional examples of processes that may be performed on a substrate include, but are not limited to, etching (e.g., chemical etching, plasma etching, reactive ion etching, etc.) and cleaning processes.

[0005] During processing, a substrate is arranged on a substrate support assembly such as a pedestal or an electrostatic chuck (ESC) arranged in a processing chamber of the substrate processing system. A robot typically transfers substrates from one processing chamber to another in a sequence in which the substrates are to be processed. During deposition, gas mixtures including one or more precursors areintroduced into the processing chamber, and plasma is struck to activate chemical reactions. During etching, gas mixtures including etch gases are introduced into the processing chamber, and plasma is struck to activate chemical reactions. The processing chambers are periodically cleaned by supplying a cleaning gas into the processing chamber and striking plasma.SUMMARY

[0006] A substrate processing system comprises a substrate support, an edge ring arranged around the substrate support, a plurality of lift pins configured to move the edge ring, and a plurality of actuators coupled to the plurality of lift pins, respectively, the plurality of actuators configured to move the plurality of lift pins independently of each other.

[0007] In additional features, the plurality of actuators is configured to move the plurality of lift pins by different amounts.

[0008] In additional features, the plurality of actuators is configured to move at least one of the plurality of lift pins differently than others of the plurality of lift pins.

[0009] In additional features, after the edge ring is moved, the edge ring is tilted relative to a substrate being processed on the substrate support.

[0010] In additional features, the plurality of actuators is configured to move the plurality of lift pins to mitigate a process non-uniformity along an edge portion of a substrate being processed on the substrate support.

[0011] In additional features, the plurality of actuators is configured to move the plurality of lift pins to mitigate a process non-uniformity along an edge portion of a substrate being processed on the substrate support during a step of a process processing the substrate.

[0012] In additional features, the plurality of actuators is configured to move at least one of the plurality of lift pins differently than others of the plurality of lift pins based on: etch rates at different points on a surface of a substrate being processed on the substrate support, a slope of a graph of etch rate versus height of the edge ring relative to the substrate, and a height of the edge ring relative to the substrate at which the etch rates at the different points on the surface of the substrate are uniform.

[0013] In additional features, in response to an edge portion of the substrate having a different etch rate than the etch rates at the different points on the surface of the substrate, the plurality of actuators is configured to move the at least one of the plurality of lift pins to mitigate a process non-uniformity along the edge portion of the substrate.

[0014] In additional features, the plurality of actuators is configured to move at least one of the plurality of lift pins while maintaining the etch rates at the different points on the surface of the substrate within a predetermined range.

[0015] In still other features, a substrate processing system comprises a substrate support, an edge ring arranged around the substrate support, a plurality of lift pins configured to move the edge ring, and a plurality of actuators coupled to the plurality of lift pins and configured to move the plurality of lift pins, respectively. The substrate processing system comprises a controller configured to control the plurality of actuators to adjust a height of at least one of the plurality of lift pins differently than others of the plurality of lift pins.

[0016] In additional features, the controller is configured to control the plurality of actuators to adjust heights of the plurality of lift pins by different amounts.

[0017] In additional features, after the edge ring is moved, the edge ring is tilted relative to a substrate being processed on the substrate support.

[0018] In additional features, the controller is configured to adjust the height of the at least one of the plurality of lift pins to mitigate a process non-uniformity along an edge portion of a substrate being processed on the substrate support.

[0019] In additional features, the controller is configured to adjust the height of the at least one of the plurality of lift pins to mitigate a process non-uniformity along an edge portion of a substrate being processed on the substrate support during a step of a process processing the substrate.

[0020] In additional features, the controller is configured to adjust the height of the at least one of the plurality of lift pins based on: etch rates at different points on a surface of a substrate being processed on the substrate support, a slope of a graph of etch rate versus height of the edge ring relative to the substrate, and a height of the edge ring relative to the substrate at which the etch rates at the different points on the surface of the substrate are uniform.

[0021] In additional features, in response to an edge portion of the substrate having a different etch rate than the etch rates at the different points on the surface of the substrate, the controller is configured to adjust the height of the at least one of the plurality of lift pins to mitigate a process non-uniformity along the edge portion of the substrate.

[0022] In additional features, the controller is configured to adjust the height of the at least one of the plurality of lift pins while maintaining the etch rates at the different points on the surface of the substrate within a predetermined range.

[0023] In additional features, the controller is configured to select the at least one of the plurality of lift pins based on a location of the edge portion of the substrate having the different etch rate and locations of the plurality of lift pins relative to a notch on the substrate.

[0024] In still other features, a method for processing a substrate arranged on a substrate support comprises arranging an edge ring around the substrate, the edge ring being movable by a plurality of lift pins, and adjusting a height of at least one of the plurality of lift pins differently than others of the lift pins.

[0025] In additional features, the method further comprises adjusting heights of the plurality of lift pins by different amounts.

[0026] In additional features, the method further comprises tilting the edge ring relative to a plane in which the substrate lies.

[0027] In additional features, the method further comprises mitigating a process nonuniformity along an edge portion of the substrate by adjusting the height of the at least one of the plurality of lift pins.

[0028] In additional features, the method further comprises mitigating a process nonuniformity along an edge portion of the substrate by adjusting the height of the at least one of the plurality of lift pins during a step of a process processing the substrate.

[0029] In additional features, the method further comprises adjusting the height of the at least one of the plurality of lift pins based on: etch rates at different points on a surface of the substrate being processed on the substrate support, a slope of a graph of etch rate versus height of the edge ring relative to the substrate, and a height of the edge ring relative to the substrate at which the etch rates at the different points on the surface of the substrate are uniform.

[0030] In additional features, the method further comprises, in response to an edge portion of the substrate having a different etch rate than the etch rates at the different points on the surface of the substrate, adjusting the height of the at least one of the plurality of lift pins to mitigate a process non-uniformity along the edge portion of the substrate.

[0031] In additional features, the method further comprises adjusting the height of the at least one of the plurality of lift pins while maintaining the etch rates at the different points on the surface of the substrate within a predetermined range.

[0032] In additional features, the method further comprises selecting the at least one of the plurality of lift pins based on a location of the edge portion of the substrate having the different etch rate and locations of the plurality of lift pins relative to a notch on the substrate.

[0033] Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0035] FIG. 1 shows an example of a substrate processing system comprising an edge ring and lift pins used for planar and non-planar height adjustments of the edge ring according to the present disclosure;

[0036] FIGS. 2A-2C show examples of the edge ring and of the lift pins used for planar and non-planar height adjustments of the edge ring in the substrate processing system of FIG. 1 according to the present disclosure;

[0037] FIG. 3 shows a top view of a substrate support of the substrate processing system of FIG. 1 along with the lift pins;

[0038] FIG. 4 shows an example of an etch rate map of the substrate being processed in the substrate processing system of FIG. 1 that is used as an input for non-planar height adjustments of the edge ring according to the present disclosure;

[0039] FIG. 5 shows an example of a graph of etch rates versus planar edge ring heights that is used as an input for non-planar height adjustments of the edge ring according to the present disclosure;

[0040] FIG. 6 shows an example of an optimal planar height of the edge ring that is used as an input for non-planar height adjustments of the edge ring according to the present disclosure;

[0041] FIG. 7 shows an example of regions along the edges of the substrate having etch rate non-uniformity that is mitigated by controlling the heights of the lift pins using the inputs shown in FIGS. 4-6 according to the present disclosure;

[0042] FIG. 8 shows the regions of FIG. 7 along with the edge ring and the lift pins;

[0043] FIG. 9 shows a controller of the substrate processing system of FIG. 1 that uses the inputs to control the heights of the lift pins by independently controlling actuators coupled to the lift pins according to the present disclosure; and

[0044] FIG. 10 shows a method for individually controlling the heights of the lift pins to improve residual etch rate nonuniformity near the edges of the substrate according to the present disclosure.

[0045] In the drawings, reference numbers may be reused to identify similar and / or identical elements.DETAILED DESCRIPTION

[0046] In an etch process, to adjust an etch rate and radial process uniformity on a substrate, an edge ring is typically disposed around the substrate, and a height of the edge ring is adjusted to adjust process uniformity on the substrate. Typically, the height of the edge ring is adjusted using a plurality (e.g., three) lift pins. The lifts pins are raised or lowered using respective actuators to adjust the height of the edge ring. However, currently, the entire edge ring is moved up or down by the same amount. Accordingly, regardless of the position of the edge ring, the height of the edge ring is the same all around the substrate since the edge ring always lies in a plane parallel to a plane in which the substrate lies. While such uniform height adjustment of the edge ring works well for adjusting radial uniformity, the uniform height adjustment cannot effectively adjust residual non-uniformity along the edges of the substrate.

[0047] The present disclosure provides a method to improve residual non-uniformity along the edges of the substrate. The method adjusts each lift pin individually and independently of other lift pins to azimuthally improve non-radial (residual) etch rate non-uniformity near the edges of the substrate. While current uniformity adjustments only control radial uniformity, are fixed, and cannot be reset or adjusted for different applications, the residual uniformity adjustment of the method of the present disclosure can be performed on the fly during a process recipe and can be adjusted step by step (e.g., during every step of the process recipe).

[0048] More specifically, the method performs a uniformity analysis based on three inputs, which are described below in detail. Briefly, a first input includes an etch rate map (also called a polar map) comprising etch rates measured at various points (e.g., any number of points such as 49 points, 121 points, and so on) on the surface of the substrate. A second input is a sensitivity input, which is a slope of a graph of etch rate versus edge ring height. A single slope is derived by measuring etch rates for a specific etch process recipe at different edge ring heights. A third input is an optimal planar edge ring height. The optimal planar edge ring height is a height of the edge ring, with the lift pins at the same height (i.e., with the edge ring in a plane parallel to a plane in which the substrate lies), at which the radial uniformity is uniform.

[0049] The three lift pins are typically installed at fixed locations around the substrate support. Accordingly, the locations of the three lift pins relative to a notch on the substrate are fixed and do not change for an etch chamber. Etch rates and non- uniformity along an edge portion of the substrate may vary relative to the rest of the substrate. Based on the known and fixed locations of the three lift pins relative to the notch on the substrate and the location of the edge portion with the non-uniformity relative to the notch on the substrate, the method selects one or more lift pins closest to the edge portion having the non-uniformity. The method then uses the three inputs described above to determine the amounts by which each of the one or more lift pins should be moved up or down to improve the residual etch rate nonuniformity in the edge portion having the non-uniformity.

[0050] In some examples, only one or two of the three lift pins are adjusted while keeping the third lift pin at the same position (i.e., without moving the third lift pin) to improve the residual etch rate nonuniformity in the edge portion having the non- uniformity. Thus, in some examples, by adjusting only one or two but not all three liftpins (i.e., by tilting the edge ring relative to the plane in which the substrate lies), the method not only maintains the radial uniformity but also improves azimuthal uniformity along the edges of the substrate. In other examples, the method may adjust heights of all three lift pins by different amounts (i.e., by tilting the edge ring relative to the plane in which the substrate lies) to improve azimuthal uniformity along the edges of the substrate while still maintaining the radial uniformity.

[0051] More specifically, based on the three inputs and the analysis described above, the method provides three outputs by which the heights of the three lift pins are controlled individually and independently of each other around the same optimized radial edge ring height to improve the residual etch rate nonuniformity. The three outputs are the three independent edge ring height adjustments (called non-planar height adjustments) derived from the optimized planar edge ring height with a small adjustment for one or more of the three lift pins so that the edge ring is no longer moved in a planar manner. The non-planar height adjustments improve residual etch rate nonuniformity near the edges of the substrate. Typically, an increase in height on one side or edge of the substrate lowers (reduces) the etch rate on that side or edge of the substrate. The three outputs are input into the process recipe for the specific step of the process recipe for the adjustment is needed. Other steps of the process recipe that do not need the azimuthal residual tuning continue with the edge ring being at the optimal planar height. These and other features of the present disclosure are described below in further detail.

[0052] The present disclosure is organized as follows. An example of a substrate processing system comprising an edge ring and lift pins used for planar and non-planar height adjustments of the edge ring is shown and described with reference to FIG. 1. Examples of the edge ring and of the lift pins are shown and described with reference to FIGS. 2A-2C. A top view of a substrate support along with the lift pins is shown and described with reference to FIG. 3. Example of an etch rate map of the substrate, a graph of etch rates versus planar edge ring heights, and an optimal planar height of the edge ring, which are used as inputs for non-planar height adjustments of the edge ring, are shown and described with reference to FIGS. 4-6. An example of regions along the edges of the substrate having etch rate non-uniformity that is mitigated by controlling heights of the lift pins using the inputs is shown and described with reference to FIGS. 7 and 8. A controller that uses the above inputs to control the heights of the lift pins by independently controlling actuators coupled to the lift pins is shown and described withreference to FIG. 9. A method for individually controlling the heights of the lift pins to improve residual etch rate nonuniformity near the edges of the substrate according to the present disclosure is shown and described with reference to FIG. 10.EXAMPLE OF SUBSTRATE PROCESSING SYSTEM

[0053] FIG. 1 shows an example of a substrate processing system (hereinafter “the system”) 10 that uses non-planar height adjustments of an edge ring according to the present disclosure. The system 10 uses inductively coupled plasma to etch substrates such as semiconductor wafers. While only one processing chamber is shown, the system 10 may comprise additional processing chambers and may also comprise a chamber that performs metrological measurements of the substrates processed in these processing chambers.

[0054] The system 10 includes a coil driving circuit 11. The coil driving circuit 11 includes a radio frequency (RF) source 12, a pulsing circuit 14, and a tuning circuit (i.e., matching circuit) 13. The RF source 12 generates an RF signal. The pulsing circuit 14 controls a transformer coupled plasma (TCP) envelope of the RF signal and varies a duty cycle of TCP envelope (e.g., between 1% and 99%) during operation. The pulsing circuit 14 and the RF source 12 can be combined or separate. The tuning circuit 13 may be directly connected to an inductive coil 16. While a single coil is shown for example, the system 10 may use a plurality of coils (e.g., inner and outer coils). The tuning circuit 13 tunes an output of the RF source 12 to a desired frequency and / or a desired phase, and matches an impedance of the inductive coil 16.

[0055] A dielectric window 24 is arranged along a top side of a processing chamber 28. The processing chamber 28 comprises a substrate support (or pedestal) 30 to support a substrate 34. The substrate support 30 may include an electrostatic chuck (ESC), a mechanical chuck, or other type of chuck. The substrate support 30 comprises a baseplate 32. The baseplate 32 is made of a metallic material (e.g., aluminum or an alloy). A ceramic plate 33 is arranged on a top surface of the baseplate 32. A thermal resistance layer 36 made of an electrically and thermally insulating material is disposed between the ceramic plate 33 and the baseplate 32. The substrate 34 is arranged on the ceramic plate 33 during processing. A plurality of heaters 35 is arranged in the ceramic plate 33 to heat the substrate 34 during processing. For example, the heaters 35 may comprise printed conductive traces embedded in the ceramic plate 33.

[0056] The baseplate 32 further includes a cooling system 38 to cool the substrate support 30. The cooling system 38 uses a fluid supplied by a fluid delivery system 39 to cool the substrate support 30. In addition, the fluid delivery system 39 can supply the fluid to manifolds (not shown) arranged on the dielectric window 24 to cool portions of the dielectric window 24.

[0057] A gas delivery system 56 may be used to supply a process gas mixture to the processing chamber 28. The gas delivery system 56 may include process and inert gas sources 57, a gas metering system 58 including valves and mass flow controllers (MFCs), and a manifold 59. A gas injector 63 may be arranged at a center of the dielectric window 24 and is used to inject gas mixtures from the gas delivery system 56 into the processing chamber 28. Additionally or alternatively, the gas mixtures may be injected from the side of the processing chamber 28.

[0058] When a process gas is supplied to the processing chamber 28, a plasma 41 is generated inside of the processing chamber 28 by supplying RF power from the coil driving circuit 11 to the inductive coil 16. The plasma 41 etches an exposed surface of the substrate 34. An RF source 50, a pulsing circuit 51 , and a bias matching circuit 52 may be used to bias the substrate support 30 during processing to control ion energy.

[0059] The substrate support 30 further includes an edge ring 40; a support ring 42; a plurality of lift pins 46-1 , 46-2, 46-3; and a plurality of actuators 48-1 , 48-2, 48-3. The lift pins 46-1 , 46-2, 46-3 are collectively called the lift pins 46 and individually called the lift pin 46. The actuators 48-1 , 48-2, 48-3 are collectively called the actuators 48 and individually called the actuator 48. Only one lift pin 46-1 and only one actuator 48-1 are shown in FIG. 1. All three lift pins 46 and all three actuators 48 are shown and described below with reference to FIG. 2C. The lift pins 46 and the actuators 48 provide the non-planar height adjustments of the edge ring 40 to improve the residual etch rate nonuniformity near the edges of the substrate 34 as described below in detail with reference to the remaining figures.

[0060] Briefly, the support ring 42 surrounds the substrate support 30 and supports the edge ring 40. The lift pins 46 pass through the support ring 42. First ends of the lift pins 46 contact the edge ring 40. Second ends of the lift pins 46 are coupled to the respective actuators 48. The actuators 48 move the respective lift pins 46 up and down to provide the non-planar height adjustments of the edge ring 40 to improve the residual etch rate nonuniformity near the edges of the substrate 34.

[0061] A temperature controller 64 is connected to the heaters 35 and controls the heaters 35 to control a temperature of the substrate support 30 and the substrate 34. The substrate support 30 and the dielectric window 24 include temperature sensors 31 , 25 to sense temperatures of substrate support 30 and the dielectric window 24. The temperature controller 64 communicates with the fluid delivery system 39 to control fluid flow through the cooling system 38 to cool the substrate support 30 based on feedback from the temperature sensor 31. The temperature controller 64 also controls fluid flow though the manifold arranged over the dielectric window 24 to cool the dielectric window 24 based on feedback from the temperature sensor 25.

[0062] An exhaust system 65 includes a valve 66 and pump 67 to control pressure in the processing chamber 28 and / or to remove reactants from the processing chamber 28 by purging or evacuation. A controller 70 (also called system controller) controls the etching process. The controller 70 controls the components of the substrate processing system 10. For example, the controller 70 monitors system parameters and controls delivery of the gas mixture from the gas delivery system 56; striking, maintaining, and extinguishing the plasma 41 ; removal of reactants from the processing chamber 28; supply of fluid from the fluid delivery system 39; height adjustments of the edge ring 40 by controlling the actuators 48; and so on. Additionally, the controller 70 controls various aspects of the coil driving circuit 11 , the RF source 50, the pulsing circuit 51 , and the bias matching circuit 52, and so on. A user interface (Ul) 71 allows operators to interact with the substrate processing system 10 via the controller 70.

[0063] FIGS. 2A-2C show examples of mechanisms for planar and non-planar height adjustments of the edge ring using the three lift pins. Elements identified in FIGS. 2A- 2C using the same reference numerals that are shown and described with reference to FIG. 1 are not described again for brevity. FIG. 2A shows a cross-sectional view of the substrate support 30. FIG. 2B shows a partial cross-sectional view of the edge ring 40, the support ring 42, and the lift pin 46. FIG. 2C shows a side view of the substrate support 30 and shows all three lift pins 46 and all three actuators 48.

[0064] Throughout the present disclosure, the edge ring 40 and the support ring 42 are shown only as examples of respective rings. Other configurations (e.g., sizes, shapes, and geometries) of these and additional rings may be used. The edge ring 40 can comprise dielectric and electrically nonconductive material such as quartz, ceramic, silicon carbide, or any combination of these materials. Further, the edge ring 40 is notbiased (e.g., not supplied with any electrical power such as RF or DC bias). Also, throughout the present disclosure, an axis parallel to a plane in which the substrate 34 lies is called a horizontal axis, x-axis, or a first axis as shown in FIGS. 2A onwards; and an axis perpendicular to the plane in which the substrate 34 lies is called a vertical axis, z-axis, an axis of the substrate support 30, or a second axis as shown in FIGS. 2A onwards.

[0065] Further, throughout the present disclosure, three lift pins 46 are shown and described for example only. Instead, a plurality of lift pins 46 may be used. For example, the three lift pins 46 may be spaced apart from each other by 120 degrees as shown in FIGS. 3 and 8. Alternatively, if four lift pins are used, the four lift pins may be spaced apart from each other by 90 degrees, and so on. Any number of lift pins can be used and can be arranged in any manner so long as the lift pins can be individually raised and lowered to adjust the height of the edge ring 40 uniformly as well as non- uniformly relative to the substrate 34. Regardless of the number of lift pins 46 used and regardless of geometries of the edge ring 40 and the support ring 42 described below, the principles of independent height adjustments of the three lift pins 46 described in the present disclosure apply equally to any other arrangement and design of the edge ring 40, the support ring 42, and any additional rings if used, to improve the residual etch rate nonuniformity near the edges of the substrate 34.EXAMPLE OF EDGE RING AND LIFT PINS

[0066] In FIGS. 2A and 2B, the edge ring 40 and the support ring 42 are annular. As described below, the edge ring 40 is mounted on the support ring 42, and the support ring 42 supports the edge ring 40. For example, the edge ring 40 has a shape of an inverted letter “U” of the English alphabet. In the example shown, the edge ring 40 comprises a horizontal (first) portion 100 and two vertical (second and third) portions 102, 104. The second and third portions 102, 104 extend perpendicularly downwards along the z-axis from two ends of the first portion 100.

[0067] In some examples, at least one of the second and third portions 102, 104 may extend downwards from the two ends of the first portion 100 at an angle relative to the z-axis. For example, the second portion 104 may extend downwards and radially outwards from one end of the first portion 100 at an angle relative to the z-axis, and the third portion 106 may extend downwards and radially inwards from another end of the first portion 100 at an angle relative to the z-axis.

[0068] The first, second, and third portions 100, 102, 104 define an annular groove (hereinafter “the groove”) 106 of the edge ring 40. In some examples, one or more corners on outside edges and inside edges of the edge ring 40 may be chamfered. Depending on the angle at which the second and third portions 102, 104 extend downwards from the two ends of the first portion 100, the inner walls of the groove 106 may be perpendicular to the first portion 100 (i.e., parallel to the z-axis) or may extend downwards from a lower surface of the first portion 100 at an angle relative to the z- axis.

[0069] In some examples, the first portion 100 may have a first thickness (measured along the z-axis), and each of the second and third portions 102, 104 may have a second thickness (measured along the x-axis) that is different than the first thickness. In other examples, the first and second thicknesses may be the same. In some examples, the heights (lengths) of the second and third portions 102, 104 (measured along the z- axis) may be equal while in other examples, the heights (lengths) of the second and third portions 102, 104 (measured along the z-axis) may be unequal.

[0070] In some examples, the width (length) of the first portion (measured along the x- axis) and the heights (lengths) of the second and third portions 102, 104 (measured along the z-axis) may be unequal. In other examples, the width (length) of the first portion (measured along the x-axis) and the heights (lengths) of the second and third portions 102, 104 (measured along the z-axis) may be equal.

[0071] Further, in some examples, the groove 106 may be formed at a center of the first portion 100 (i.e., a center of the groove 106 may be equidistant from outer and inner diameters of the edge ring 40). In other examples, the groove 106 may be offset from the center of the first portion 100 (i.e., the center of the groove 106 may be closer to the outer diameter of the edge ring 40 or may be closer to the inner diameter of the edge ring 40). The first, second, and third portions 100, 102, 104 may have any combination of the thicknesses, heights, lengths, and widths; and in some of the combinations, the groove 106 may be at the center of the first portion 100 or may be offset from the center of the first portion 100.

[0072] In FIG. 2A, the ceramic portion 33 has an upper portion on which the substrate 34 is arranged and a lower portion that is attached to the top surface of the baseplate 32. The upper portion of the ceramic portion 33 is smaller in diameter than the lower portion of the ceramic portion 33. The upper and lower portions of the ceramic portion33 define a ledge 110. In other words, the upper portion of the ceramic plate 33 includes an annular cutout or a ledge 110. The ledge 110 extends radially outwards and is parallel to the x-axis. The ledge 110 and the lower portion of the ceramic portion 33 have the same outer diameter (OD). An inner diameter (ID) of the ledge 110 is less than the OD of the ledge 110 and the lower portion of the ceramic portion 33. The ID of the ledge 110 is the same as an OD of the upper portion of the ceramic portion 33.

[0073] In FIGS. 2A and 2B, a first end of the support ring 42 proximate to the substrate34 includes a slot 112 along an ID of the support ring 42. The slot 112 extends radially inwards parallel to the x-axis from the ID of the support ring 42. The slot 112 rests on the ledge 110. An outer edge of the substrate 34 extends slightly over the ID of the ledge 110 along the x-axis and hangs over a top end of a radially inner portion of the slot 112.

[0074] Additionally, the first end of the support ring 42 includes a ledge 114 along an OD of the support ring 42. The second portion 102 of the edge ring 40 lies on the ledge 114. A width of the ledge 114 measured along the x-axis is greater than or equal to the width of the second portion 102 of the edge ring 40 measured along the x-axis. The third portion 104 of the edge ring 40 lies in the slot 112. A width of the slot 112 measured along the x-axis is greater than the width of the third portion 104 of the edge ring 40 measured along the x-axis.

[0075] In some examples, depths of the slot 112 and the ledge 114 (measured along the z-axis) are the same. In other examples, depending on the geometries of the second and third portions 102, 104 of the edge ring 40 described above, the depths of the slot 112 and the ledge 114 may be unequal. The outer edges of the substrate 34 do not contact the ID of the edge ring 40 regardless of the positioning of the edge ring 40.

[0076] The first end of the support ring 42 also includes a protrusion (or a ridge) 116 between the slot 112 and the ledge 114. The protrusion 116 extends into the groove 106 of the edge ring 40. In some examples, a height of the protrusion 116 (measured along the z-axis) is the same as the depths of the slot 112 and the ledge 114. In other examples, depending on the geometries of the second and third portions 102, 104 of the edge ring 40 described above, the height of the protrusion 116 may be different than the depths of the slot 112 and the ledge 114.

[0077] The actuators 48 are attached to a second end of the support ring 42 that is near a bottom end of the baseplate 32. First ends of the lift pins 46 are coupled to therespective actuators 48. The lift pins 46 extend upwards from the actuators 48 through the support ring 42 and through the protrusion 116 along the z-axis. Second ends of the lift pins 46 contact the bottom surface of the first portion 100 of the edge ring 40. The controller 70 shown in FIG. 1 controls the actuators 48 to move the lift pins 46 up and down, and the lift pins 46 move the edge ring 40 up and down as described below in further detail.

[0078] FIG. 2C shows the side view of the substrate support 30. The substrate support 30 is not visible because the substrate support 30 is surrounded by the support ring 42. All the lift pins 46 and all the actuators 48 are shown. The lift pins 46 are shown using dashed lines because the lift pins 46 pass through the support ring 42 and are therefore not visible in the side view. The groove 106 in the edge ring 40 is also not visible because only the outer surface of the edge ring 40 is visible in the side view.

[0079] FIG. 3 shows a top view of the substrate support 30 along with the lift pins 46. The upper portion of the ceramic portion 33 is shown using a dashed circle because the substrate 34 covers the upper portion of the ceramic portion 33. The substrate 34 includes a notch 37 on an outer edge (i.e., along an OD) of the substrate 34. The lift pins 46 are shown by dashed circles because the lift pins 46 lie under the edge ring 40 and do not pass through the edge ring 40.

[0080] The locations of the lift pins 46 are fixed in the substrate support 30 relative to the notch 37 in the substrate 34. The fixed locations of the lift pins 46 relative to the notch 37 in the substrate 34 are useful in individually controlling the lift pins 46 to improve the residual etch rate nonuniformity near the edges of the substrate 34 as described below in detail with reference to the remaining figures.

[0081] Specifically, the controller 70 shown in FIG. 1 uses three inputs to output individual height adjustments for the three lift pins 46 to improve the residual etch rate nonuniformity near the edges of the substrate 34. The three inputs are the etch rate map, the sensitivity, and the optimal planar height of the edge ring 40. For example, an operator of the system 10 may provide the three inputs to the controller 70 via the Ul 71 . Alternatively, the controller 70 can obtain the three inputs from data collected by the controller 70 from various components of the system 10 during substrate processing. Each of these inputs are now described below in detail with reference to FIGS. 4-6.INPUTS FOR ADJUSTING NON-PLANAR HEIGHT OF EDGE RING

[0082] FIG. 4 shows an example of an etch rate map (also called a polar map) of the substrate 34, which is the first input used by the controller 70 to improve the residual etch rate nonuniformity near the edges of the substrate 34. The dots shown at 118 represent points on the surface of the substrate 34 at which the etch rate is measured with the edge ring 40 positioned at the optimal planar height. The etch rate map provides the etch rates at the points shown by the dots 118 on the surface of the substrate 34. With the edge ring 40 positioned at the optimal planar height, the etch rates at the points shown by the dots 118 on the surface of the substrate 34 are substantially uniform (e.g., within a specified range) and indicate the radial etch rate uniformity of the substrate 34.

[0083] However, the etch rates along the edges of the substrate 34 may vary and may not be uniform, which can cause etch rate non-uniformity along the edges of the substrate 34 as shown and explained be low with reference to FIGS. 7 and 8. The method of the present disclosure remedies the etch rate non-uniformity along the edges of the substrate 34 as described below. The controller 70 uses the etch rates at the points shown by the dots 118 on the surface of the substrate 34 as a reference to calculate height adjustments for the lift pins 46. The controller 70 provides the height adjustments without disturbing the etch rates at the points shown by the dots 118 on the surface of the substrate 34 (i.e., while maintaining the radial etch rate uniformity of the substrate 34).

[0084] FIG. 5 shows an example of a graph of etch rates versus planar edge ring heights. At each planar height of the edge ring 40, the second ends of the lift pins 46 in contact with the edge ring 40 are in the same plane parallel to the plane in which the substrate 34 lies. In other words, at each planar height of the edge ring 40, the first portion 100 of the edge ring 40 is in the same plane parallel to the plane in which the substrate 34 lies. As the planar height of the edge ring 40 increases, the etch rate on the substrate 34 (at the points shown by the dots 118 on the surface of the substrate 34) decreases. A slope of the graph, which is called sensitivity as described above, is the second input used by the controller 70 to improve the residual etch rate nonuniformity near the edges of the substrate 34.

[0085] FIG. 6 shows an example of the optimal planar height H of the edge ring 40. While the support ring 42 is omitted to illustrate the optimal planar height H of the edgering 40 clearly, the support ring 42 is presumed to be present to support the edge ring 40 as described above. When the edge ring is at height H, the lift pins 46 are at equal heights, and the first portion 100 of the edge ring 40 is parallel to the plane in which the substrate 34 lies. The etch rates at the dots 118 in the etch rate map shown in FIG. 4 are substantially uniform (e.g., within a specified range), and the radial etch rate uniformity of the substrate 34 is optimal (e.g., within a specified range). The optimal planar height H of the edge ring 40 is the third input used by the controller 70 to improve the residual etch rate nonuniformity near the edges of the substrate 34.EXAMPLE OF EDGE REGIONS WITH RESIDUAL NON-UNIFORMITY

[0086] FIG. 7 shows an example of regions 120, 122 along the edges of the substrate 34 having etch rate non-uniformity. Only two regions are shown as examples. Any number of regions along the edges of the substrate 34 may have etch rate non- uniformity. The method of the present disclosure of changing non-planar height of the edge ring 40 to improve the residual etch rate nonuniformity near the edges of the substrate 34 described throughout the present disclosure applies equally to mitigating residual etch rate non-uniformity in any number of regions along the edges of the substrate 34.

[0087] For example, the etch rates in the regions 120, 122 may be greater or less the etch rates at the dots 118 shown in FIG. 4. The difference between the etch rates in the regions 120, 122 and the etch rates at the dots 118 that are neighboring the regions 120, 122 is an amount of residual etch rate non-uniformity in the regions 120, 122. The difference (i.e., the amount of residual etch rate non-uniformity) may be greater than or equal to a predetermined threshold.

[0088] FIG. 8 shows the regions 120, 122 along with the edge ring 40 and the lift pins 46. The controller 70 correlates the locations of the regions 120, 122 relative to the notch 37 on the substrate 34 with the locations of the lift pins 46, which are fixed relative to the notch 37 on the substrate 34. The controller 70 selects the lift pins 46 of which the height needs to be adjusted based on the correlation. The controller 70 calculates an amount by which to adjust the heights of the selected lift pins 46 based on the three inputs and based on the difference between the etch rates in the regions 120, 122 and the etch rates at the dots 118. The controller 70 outputs the height adjustments for the lift pins 46 to the process recipe being performed on the substrate 34 to improve the residual etch rate nonuniformity in the regions 120, 122. The outputs for adjustingthe heights of the three lift pins 46 are shown as hi (P1 ), h2(P2), and h3(P3) in FIG. 9, where hi(Pi) denotes height hi of lift pin Pi.

[0089] The controller 70 can generate the outputs during each step of the process recipe except for steps of the process recipe that may not require height adjustments. The actuators 48 adjust the heights of the lift pins 47 according to the height adjustments provided by the controller 70 during each step of the process recipe except for steps of the process recipe that may not require height adjustments.

[0090] FIG. 9 shows the controller 70 controlling the heights of the lift pins 46 individually (i.e., independently of each other) by controlling the actuators 48 to improve the residual etch rate nonuniformity near the edges of the substrate 34. Based on the three inputs and the difference between the etch rates in the regions 120, 122 and the etch rates at the dots 118 (i.e., based on the amount of non-uniformity in the regions 120, 122), the controller 70 may change (increase and / or decrease) heights of one or more lift pins 46 by different amounts. In some examples, the controller 70 may raise the lift pins 46-1 , 46-2, 46-3 (i.e., lift pins P1 , P2, P3) by amounts hi , h2, and h3, respectively, where hi , h2, and h3 are unequal. In some examples, the controller 70 may lower the lift pins 46-1 , 46-2, 46-3 by amounts hi , h2, and h3, respectively, where hi , h2, and h3 are unequal.

[0091] In other examples, the controller 70 may raise or lower only one lift pin 46. In other examples, the controller 70 may raise or lower only two lift pins 46, by the same amount or by different amounts. In still other examples, the controller 70 may raise one lift pin 46 and lower another lift pin 46, by the same or different amounts. In still other examples, the controller 70 may raise one lift pin 46 and lower the other lift pins 46, by the same or different amounts. In still other examples, the controller 70 may raise two lift pins 46 by the same or different amounts and may lower the third lift pin 46 by a still different amount, and so on.

[0092] When the height adjustments to the lift pins 46 are such that at least one lift pin 46 is at a different height than the other lift pins 46, the edge ring 40 is not horizontal (i.e., the edge ring 40 does not lie in a plane parallel to the plane in which the substrate 34 lies). Instead, the edge ring 40 is tilted and lies at an acute angle relative to the plane in which the substrate 34 lies (i.e., relative to the x-axis). Regardless of which lift pin 46 is or lift pins 46 are adjusted to azimuthally improve the residual etch ratenonuniformity in the regions 120, 122, the controller 70 calculates the adjustments so as to not alter the radial uniformity of the substrate 34 shown in FIG. 4.

[0093] Thus, the controller 70 can adjust the non-planar height of the edge ring 40 azimuthally to improve the residual etch rate nonuniformity near the edges of the substrate 34. The controller 40 can also adjust the raise or lower the lift pins 46-1 , 46-2, 46-3 (i.e., lift pins P1 , P2, P3) by amounts hi , h2, and h3, respectively, where hi , h2, and h3 are equal. Thus, the controller 70 can adjust the planar height of the edge ring 40 to improve the radial etch rate uniformity of the substrate 34.

[0094] Increasing the height of the edge ring 40 on one side by raising one or more lift pins 46 relative to another side of the edge ring 40 decreases the etch rate on the one side of the edge ring 40. Alternatively, decreasing the height of the edge ring 40 on one side by raising one or more lift pins 46 relative to another side of the edge ring 40 increases the etch rate on the one side of the edge ring 40. The controller 70 uses the three inputs to increase and / or decrease the height of the edge ring 40 in a non-planar manner as described above. By adjusting the non-planar height of the edge ring 40 (i.e., by tilting the edge ring 40 relative to the plane in which the substrate 34 lies), the residual non-uniformity in one or more regions along the edges of the substrate 40 is mitigated.METHOD TO ADJUST NON-PLANAR HEIGHT OF EDGE RING

[0095] FIG. 10 shows a method 200 for controlling the heights of the lift pins 46 individually (i.e., independently of each other) to azimuthally adjust the planar height of the edge ring 40 to improve the residual etch rate nonuniformity near the edges of the substrate 34. For example, the controller 70 may perform the method 200.

[0096] At 202, the controller 70 obtains the first input, which is the etch rate map data (i.e., the polar map shown and described above with reference to FIG. 4) for the process recipe being performed on the substrate 34. At 204, the controller 70 obtains the second input, which is the sensitivity data (i.e., the slope of the graph of etch rate versus height of the edge ring 40 shown and described above with reference to FIG. 5). At 206, the controller obtains the third input, which is the optimal planar height of the edge ring 40 shown and described above with reference to FIG. 6.

[0097] At 208, the controller 70 obtains data about non-uniformity in one or more regions along the edges of the substrate 34 (e.g., regions 120, 122 shown anddescribed above with reference to FIG. 7). At 210, the controller 70 identifies or determines which lift pin 46 is or which lift pins 46 are proximate to the regions having the non-uniformity along the edges of the substrate 34 as shown and described above with reference to FIG. 8.

[0098] At 212, the controller 70 calculates height adjustments hi , h2, h3 for the lift pins 46-1 (P1), 46-2 (P2), 46-3 (P#), respectively, based on the three inputs and the amount of non-uniformity in the regions having the non-uniformity along the edges of the substrate 34 as compared to the etch rates at the dots 118 that are neighboring the regions as described above with reference to FIGS. 8 and 9. At 214, the controller 70 applies the height adjustments to the lift pins 46 by controlling the respective actuators 48 according to the height adjustments for the respective lift pins 46.

[0099] At 216, the controller 70 advances the process to the next step. At 218, the controller 70 determines if any height adjustments to the lift pins 46 are needed in the next step of the process. If yes, the method 200 returns to step 210. If no, at 220, the controller 70 determines if the process is complete. If not, the method 200 returns to step 216. If yes, the method 200 ends.

[0100] The foregoing description is merely illustrative in nature and is not intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims.

[0101] It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the examples is described above as having certain features, any one or more of those features described with respect to any one of the examples of the disclosure can be implemented in and / or combined with features of any of the other examples, even if that combination is not explicitly described. In other words, the described examples are not mutually exclusive, and permutations of one or more examples with one another remain within the scope of this disclosure.

[0102] Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,”“above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

[0103] In some implementations, a controller is part of a system, which may be part of the above-described examples. Such systems can comprise semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and / or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate.

[0104] The electronics may be referred to as the “controller,” which may control various components or subparts of the system or systems. The controller, depending on the processing requirements and / or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and / or load locks connected to or interfaced with a specific system.

[0105] Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software).

[0106] Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some examples, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0107] The controller, in some implementations, may be a part of or coupled to a computer that is integrated with the system, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process.

[0108] In some examples, a remote computer (e.g., a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and / or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control.

[0109] Thus, as described above, the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.

[0110] Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and / or manufacturing of semiconductor wafers.

[0111] As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing factory.

Claims

CLAIMSWhat is claimed is:1 . A substrate processing system comprising: a substrate support; an edge ring arranged around the substrate support; a plurality of lift pins configured to move the edge ring; and a plurality of actuators coupled to the plurality of lift pins, respectively, the plurality of actuators configured to move the plurality of lift pins independently of each other.

2. The substrate processing system of claim 1 wherein the plurality of actuators is configured to move the plurality of lift pins by different amounts.

3. The substrate processing system of claim 1 wherein the plurality of actuators is configured to move at least one of the plurality of lift pins differently than others of the plurality of lift pins.

4. The substrate processing system of claim 1 wherein after the edge ring is moved, the edge ring is tilted relative to a substrate being processed on the substrate support.

5. The substrate processing system of claim 1 wherein the plurality of actuators is configured to move the plurality of lift pins to mitigate a process non-uniformity along an edge portion of a substrate being processed on the substrate support.

6. The substrate processing system of claim 1 wherein the plurality of actuators is configured to move the plurality of lift pins to mitigate a process non-uniformity along an edge portion of a substrate being processed on the substrate support during a step of a process processing the substrate.

7. The substrate processing system of claim 1 wherein the plurality of actuators is configured to move at least one of the plurality of lift pins differently than others of the plurality of lift pins based on: etch rates at different points on a surface of a substrate being processed on the substrate support; a slope of a graph of etch rate versus height of the edge ring relative to the substrate; and a height of the edge ring relative to the substrate at which the etch rates at the different points on the surface of the substrate are uniform.

8. The substrate processing system of claim 7 wherein in response to an edge portion of the substrate having a different etch rate than the etch rates at the different points on the surface of the substrate, the plurality of actuators is configured to move the at least one of the plurality of lift pins to mitigate a process non-uniformity along the edge portion of the substrate.

9. The substrate processing system of claim 7 wherein the plurality of actuators is configured to move at least one of the plurality of lift pins while maintaining the etch rates at the different points on the surface of the substrate within a predetermined range.

10. A substrate processing system comprising: a substrate support; an edge ring arranged around the substrate support; a plurality of lift pins configured to move the edge ring; a plurality of actuators coupled to the plurality of lift pins, respectively, the plurality of actuators configured to move the plurality of lift pins; and a controller configured to control the plurality of actuators to adjust a height of at least one of the plurality of lift pins differently than others of the plurality of lift pins.11 . The substrate processing system of claim 10 wherein the controller is configured to control the plurality of actuators to adjust heights of the plurality of lift pins by different amounts.

12. The substrate processing system of claim 10 wherein after the edge ring is moved, the edge ring is tilted relative to a substrate being processed on the substrate support.

13. The substrate processing system of claim 10 wherein the controller is configured to adjust the height of the at least one of the plurality of lift pins to mitigate a process non-uniformity along an edge portion of a substrate being processed on the substrate support.

14. The substrate processing system of claim 10 wherein the controller is configured to adjust the height of the at least one of the plurality of lift pins to mitigate a process non-uniformity along an edge portion of a substrate being processed on the substrate support during a step of a process processing the substrate.

15. The substrate processing system of claim 10 wherein the controller is configured to adjust the height of the at least one of the plurality of lift pins based on: etch rates at different points on a surface of a substrate being processed on the substrate support; a slope of a graph of etch rate versus height of the edge ring relative to the substrate; and a height of the edge ring relative to the substrate at which the etch rates at the different points on the surface of the substrate are uniform.

16. The substrate processing system of claim 15 wherein in response to an edge portion of the substrate having a different etch rate than the etch rates at the different points on the surface of the substrate, the controller is configured to adjust the height of the at least one of the plurality of lift pins to mitigate a process non-uniformity along the edge portion of the substrate.

17. The substrate processing system of claim 15 wherein the controller is configured to adjust the height of the at least one of the plurality of lift pins while maintaining the etch rates at the different points on the surface of the substrate within a predetermined range.

18. The substrate processing system of claim 16 wherein the controller is configured to select the at least one of the plurality of lift pins based on a location of the edge portion of the substrate having the different etch rate and locations of the plurality of lift pins relative to a notch on the substrate.

19. A method for processing a substrate arranged on a substrate support, the method comprising: arranging an edge ring around the substrate, the edge ring being movable by a plurality of lift pins; and adjusting a height of at least one of the plurality of lift pins differently than others of the lift pins.

20. The method of claim 19 further comprising adjusting heights of the plurality of lift pins by different amounts.21 . The method of claim 19 further comprising tilting the edge ring relative to a plane in which the substrate lies.

22. The method of claim 19 further comprising mitigating a process non-uniformity along an edge portion of the substrate by adjusting the height of the at least one of the plurality of lift pins.

23. The method of claim 19 further comprising mitigating a process non-uniformity along an edge portion of the substrate by adjusting the height of the at least one of the plurality of lift pins during a step of a process processing the substrate.

24. The method of claim 19 further comprising adjusting the height of the at least one of the plurality of lift pins based on: etch rates at different points on a surface of the substrate being processed on the substrate support; a slope of a graph of etch rate versus height of the edge ring relative to the substrate; and a height of the edge ring relative to the substrate at which the etch rates at the different points on the surface of the substrate are uniform.

25. The method of claim 24 further comprising, in response to an edge portion of the substrate having a different etch rate than the etch rates at the different points on the surface of the substrate, adjusting the height of the at least one of the plurality of lift pins to mitigate a process non-uniformity along the edge portion of the substrate.

26. The method of claim 25 further comprising adjusting the height of the at least one of the plurality of lift pins while maintaining the etch rates at the different points on the surface of the substrate within a predetermined range.

27. The method of claim 26 further comprising selecting the at least one of the plurality of lift pins based on a location of the edge portion of the substrate having the different etch rate and locations of the plurality of lift pins relative to a notch on the substrate.

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