Edge ring voltage and phase measurement and control for substrate processing systems

Abstract

A voltage control system is disclosed that includes an edge ring disposed on a substrate support and configured to surround an outer periphery of the substrate, a tunable edge sheath (TES) ring, a generator, and a controller. The TES ring includes a TES power electrode capacitively coupled to the edge ring and configured to receive a first radio frequency (RF) voltage signal, and a TES probe electrically coupled to the edge ring and configured to detect a second RF voltage signal at the edge ring. The controller is configured to control the generator to adjust the first RF voltage signal based on the second RF voltage signal.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of U.S. Provisional Application No. 63 / 389,520, filed July 15, 2022, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to a system for controlling radio frequency (RF) voltage in a substrate processing system, and more particularly to an edge ring voltage control system. [Background technology]

[0003] The background art provided herein is intended to provide a general background to the present disclosure, and the work of the inventors named herein, to the extent described in this background art, along with aspects of the description that would not normally be considered prior art at the time of filing, are not admitted expressly or impliedly as prior art to the present disclosure.

[0004] A substrate processing system typically includes multiple processing chambers (also called processing modules) for performing deposition, etching, and other processes on substrates, such as semiconductor wafers. Examples of processes that may be performed on substrates include 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). Further examples of processes that may be performed on substrates include etching (e.g., chemical etching, plasma etching, reactive ion etching, etc.) and cleaning processes.

[0005] During processing, a substrate is placed on a substrate support (such as a pedestal or electrostatic chuck (ESC)) in a processing chamber of a substrate processing system. Typically, a computer-controlled robot moves the substrates from one processing chamber to another in the order in which they are processed. During deposition, a gas mixture containing one or more precursors is introduced into the processing chamber and a plasma is ignited to activate a chemical reaction. During etching, a gas mixture containing an etching gas is introduced into the processing chamber and a plasma is ignited to activate a chemical reaction. The processing chamber is periodically cleaned by supplying a cleaning gas into the processing chamber and igniting a plasma. Summary of the Invention

[0006] A voltage control system is disclosed that includes an edge ring disposed on a substrate support and configured to surround an outer periphery of the substrate, a tunable edge sheath (TES) ring, a generator, and a controller. The TES ring includes a TES power electrode capacitively coupled to the edge ring and configured to receive a first radio frequency (RF) voltage signal, and a TES probe electrically coupled to the edge ring and configured to detect a second RF voltage signal at the edge ring. The controller is configured to control the generator to adjust the first RF voltage signal based on the second RF voltage signal.

[0007] In other features, the TES power electrode and the TES probe are at least partially embedded in the TES ring. In other features, the TES power electrode and the TES probe are completely embedded in the TES ring.

[0008] In other features, the TES probe is in direct contact with the edge ring for direct detection of the second RF voltage signal. In other features, the TES probe is capacitively coupled to the edge ring for indirect detection of the second RF voltage signal.

[0009] In other features, the edge ring is disposed on the TES ring and is in contact with the TES ring. In other features, the TES ring has a bottom surface. The top surface of the TES probe extends parallel to and faces the bottom surface of the TES ring.

[0010] In other features, at least one of the TES power electrode and the TES probe is ring-shaped. In other features, the TES power electrode is ring-shaped. The TES probe is disposed radially inward or radially outward of the TES power electrode.

[0011] In other features, the TES probe extends vertically and is positioned radially outward of the TES power electrode. In other features, the TES power electrode is ring-shaped and includes an opening, with a portion of the TES probe extending through the opening.

[0012] In other features, there is a gap between the TES power electrode and the TES probe. In other features, the TES power electrode is ring-shaped. The TES probe is ring-shaped.

[0013] In other features, the half cross-sectional width of the TES probe is greater than the half cross-sectional width of the TES probe. In other features, the half cross-sectional width of the TES probe is equal to the half cross-sectional width of the TES probe. In other features, the half cross-sectional width of the TES probe is less than the half cross-sectional width of the TES probe.

[0014] In other features, the TES probe is vertically offset from the TES power electrode. In other features, the TES probe is positioned closer to the edge ring than the TES power electrode.

[0015] In other features, the TES ring is formed of a dielectric material, and the TES power electrode and the TES probe are embedded in the TES ring such that a portion of the dielectric material is disposed between i) the TES power electrode and the TES probe, and ii) the edge ring.

[0016] In other features, the voltage control system further comprises a sensor configured to detect an amplitude and a phase of a third RF voltage signal supplied to the RF electrode of the substrate support, and the controller is configured to adjust the first RF voltage signal based on the amplitude and phase of the second RF voltage signal and the amplitude and phase of the third RF voltage signal.

[0017] In other features, the controller is configured to adjust the first RF voltage signal to match the second RF voltage signal in at least one of amplitude and phase to the third RF voltage signal. In other features, the controller is configured to determine if the second RF voltage signal is unstable and to compensate for the instability of the second RF voltage signal by adjusting the first RF voltage signal.

[0018] In other features, the controller is configured to determine a health status of at least one of the edge ring or the TES ring based on the second RF voltage signal, and to determine at least one of whether to allow processing of the substrate to continue and whether to implement a corrective action based on the health status.

[0019] In another feature, a substrate processing system is disclosed that includes a voltage control system, a substrate support having an RF electrode, and a sensor configured to detect a third RF voltage signal supplied to the RF electrode, and a controller configured to adjust a first RF voltage signal based on both the second RF voltage signal and the third RF voltage signal.

[0020] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. [Brief explanation of the drawings]

[0021] The present disclosure will become more fully understood from the detailed description and accompanying drawings set forth below.

[0022] [Figure 1] 1 is a functional block diagram illustrating a substrate processing system including an edge ring voltage control system according to the present disclosure.

[0023] [Figure 2] FIG. 1 illustrates an example edge ring voltage control system according to the present disclosure.

[0024] [Figure 3] 1 is a cross-sectional side view of a substrate support including an edge ring and an example adjustable edge sheath (TES) ring with a direct measurement TES probe according to the present disclosure.

[0025] [Figure 4] 1 is a cross-sectional side view of a substrate support including an edge ring and an example TES ring with an indirect measurement TES probe according to the present disclosure.

[0026] [Figure 5] 1 is a cross-sectional side view of a substrate support including an edge ring and an example TES ring having an indirect measurement TES probe facing the edge ring over a larger surface area than the TES power electrode.

[0027] [Figure 6] 1A is a top cross-sectional view illustrating an example of a TES ring including a ring-shaped TES power electrode with an opening for a direct measurement TES probe according to the present disclosure.

[0028] [Figure 7] 1 is a top cross-sectional view of an example TES ring with a ring-shaped TES power electrode and a ring-shaped indirect measurement TES probe according to the present disclosure.

[0029] [Figure 8A] 1 illustrates a method for measuring and controlling edge ring voltage and phase, including diagnostic operations, in accordance with the present disclosure. [Figure 8B]1 illustrates a method for measuring and controlling edge ring voltage and phase, including diagnostic operations, in accordance with the present disclosure.

[0030] In the drawings, the same numbers may be used to identify similar and / or identical elements. DETAILED DESCRIPTION OF THE INVENTION

[0031] In a process chamber for performing plasma etching processes on semiconductor substrates (typically under vacuum), an edge ring (also called a top ring) is disposed adjacent to and around the outer periphery of a substrate support. The edge ring may be supplied with an RF voltage via TES hardware to adjust the shape of the plasma near the edge of the substrate supported by the substrate support. The TES hardware may include a TES ring having a TES power electrode that receives the RF voltage. The TES power electrode is embedded in the TES ring and capacitively coupled to the edge ring. The RF voltage of the TES power electrode may be set to improve etch uniformity of the substrate.

[0032] The controller may detect the RF voltage output by the RF generator and / or supplied to the TES power electrode and adjust the RF voltage to provide a target etching or deposition profile. Control of the RF voltage can be inaccurate because the amplitude and phase of the RF voltage generated by the RF generator often differ from the actual amplitude and phase of the RF voltage at the edge ring. This is due to i) capacitive coupling between the corresponding substrate support and the edge ring, ii) capacitive coupling between the TES power electrode and the edge ring, iii) impedance variations in the plasma above the substrate support and the edge ring, and iv) parasitic coupling of substrate system components. The plasma impedance changes with differences in applied RF voltage, which leads to differences in the amplitude and phase of the RF voltage from the RF generator and the actual RF voltage at the edge ring. Differences in amplitude and phase can also occur due to differences in system configuration, such as differences in the placement height of the edge ring relative to the substrate support and / or the substrate supported on the substrate support. Therefore, there is no direct correlation between the amplitude and phase of the generated RF voltage and the amplitude and phase of the RF voltage at the edge ring.

[0033] Differences in the amplitude and phase of the RF voltage at the edge ring and the amplitude and phase of the RF voltage supplied to the substrate support can lead to etch rate non-uniformity and profile distortion at the substrate. Controlling etch rate uniformity across the surface of the substrate is difficult, especially near the outer peripheral edge of the substrate.

[0034] Examples described herein include an RF voltage detection / control system configured to directly or indirectly detect the RF voltage and phase of an edge ring and control the amplitude and phase of the RF voltage at the edge ring. The RF voltage detection / control system includes a TES ring with a TES power electrode and a TES probe. The TES probe may be in direct contact with the edge ring, adjacent to the edge ring, or indirectly coupled to the edge ring. The TES probe can directly detect the RF voltage at one or more contact points. An indirect configuration includes the TES probe being capacitively coupled to the edge ring. The TES probe may be ring-shaped and have a large surface area for indirectly detecting the RF voltage at the edge ring via capacitive coupling. The TES power electrode and TES probe may be embedded in the TES ring. In one embodiment, the TES probe extends through the corresponding TES ring to directly contact the edge ring. In another embodiment, the TES probe is embedded in the TES ring and capacitively coupled to the corresponding edge ring. These and other examples are further described below.

[0035] 1 illustrates a substrate processing system 100 including an edge ring voltage control system 101 for measuring and controlling RF voltage and phase at an edge ring 102 and, therefore, the edge of a substrate 103. The substrate processing system 100 includes a processing chamber 104, which may be configured to generate a capacitively coupled plasma. The processing chamber 104 houses the components of the substrate processing system 100 and confines the RF plasma (if utilized). The processing chamber 104 includes an upper electrode 105 and a substrate support 106 (e.g., an electrostatic chuck (ESC)) or other type of substrate support. During operation, the substrate 103 is positioned on the substrate support 106.

[0036] As an example, the upper electrode 105 may include a gas distribution apparatus 110 (such as a showerhead) for introducing and distributing process gases. The gas distribution apparatus 110 may include a stem portion with one end connected to the top surface of the processing chamber 104. The showerhead's base portion is generally cylindrical and flares radially outward from the opposite end of the stem portion away from the top surface of the processing chamber 104. The substrate-facing surface, or faceplate, of the showerhead's base portion includes a plurality of holes through which vaporized precursors, process gases, cleaning gases, or purge gases flow. Alternatively, the upper electrode 105 may include a conductive plate, and gases may be introduced in other ways.

[0037] When a plasma is utilized, an RF generation system (or RF source) 120 generates and outputs an RF voltage to one of the upper electrode 105 and the lower electrode 121. The other of the upper electrode 105 and the lower electrode 121 may be DC grounded, AC grounded, or floating. For example, the RF generation system 120 may include an RF generator 122 that generates RF power supplied to the upper electrode 105 or the lower electrode 121 by a matching / distribution network 124. In another example, not shown, a plasma may be generated inductively or remotely and then supplied to the processing chamber 104. The lower electrode 121 may be embedded in the substrate support 106.

[0038] The gas delivery system 130 includes one or more gas sources 132-1, 132-2, ..., and 132-N (collectively, gas sources 132), where N is an integer greater than zero. The gas sources 132 are connected to a manifold 140 by valves 134-1, 134-2, ..., and 134-N (collectively, valves 134) and mass flow controllers 136-1, 136-2, ..., and 136-N (collectively, mass flow controllers 136). A vapor delivery system 142 delivers vaporized precursors to the manifold 140 or to a separate manifold (not shown) connected to the processing chamber 104. The output of the manifold 140 is delivered to the processing chamber 104. The gas sources 132 may deliver process gases, cleaning gases, and / or purge gases. A valve 156 and a pump 158 may be used to evacuate reactants from the processing chamber 104 .

[0039] A system controller 160 controls the components of the substrate processing system 100. A user interface (UI) 170 interfaces with the substrate processing system 100 through the system controller 160.

[0040] Edge ring voltage control system 101 includes a system controller 160, an RF generation system 120, a TES ring 171 having a TES power electrode 172, and a TES probe 174. Edge ring voltage control system 101 may also include a lower electrode 121. System controller 160 detects the amplitude and phase of the RF voltage signal at the edge ring via TES probe 174 and, based on these measurements, controls RF generation system 120 to adjust the voltage and phase at edge ring 102 and the TES of the plasma. Examples of this control and other arrangements are described in more detail below with respect to FIGS. 2-8.

[0041] The substrate support 106 may further include a cover ring 180 and an insulating ring 182. The cover ring 180 may be provided to protect the outer edges of the rings 102 and 171. The substrate support 106 and the rings 171, 180, and 182 may be formed of ceramic and / or other dielectric materials. The cover ring 180 may be formed of quartz ceramic. The substrate support 106 and the rings 171 and 182 may be formed of alumina ceramic. The edge ring 102 may be formed of silicon carbide, stainless steel, copper, aluminum, and / or other suitable conductive materials. The lower electrode 121, the TES power electrode 172, and the TES probe 174 may be formed of copper, nickel, and / or other suitable conductive materials.

[0042] 2 illustrates an edge ring voltage control system 200 that can be implemented in the substrate processing system 100 of FIG. 1. The edge ring voltage control system 200 may include a controller 202, RF generators 204, 206, matching networks 208, 210, a measurement module 212, a TES ring 214 including a TES power electrode 216 and a TES probe 218, and a substrate support 220 including an RF electrode 222. The substrate support 220 supports a substrate 224 and may include a cover ring 226 and an insulating ring 228, which are similar to the rings 180, 182 of FIG. 1. An edge ring 230 is disposed on the TES ring and surrounds the substrate 224.

[0043] The TES ring 214 is disposed on the insulating ring 228 and is in contact with the edge ring 230. The TES power electrode 216 and the TES probe 218 may be embedded in the TES ring 214. The TES ring 214 and the edge ring 230 may be formed of materials similar to those of the rings 171 and 102 in FIG. 1. Although the TES probe 218 is illustrated radially outward from the TES power electrode 216, the TES probe 218 may also be radially inward from the TES power electrode 216. By providing the TES probe radially outward, the surface area of the TES probe 218 on the edge ring side can be increased.

[0044] In the illustrated example, the TES power electrode 216 and the TES probe 218 are capacitively coupled to the edge ring 230. The cross-sectional width W1 of the TES power electrode 216 and the cross-sectional width W2 of the TES probe may be the same or different. In one embodiment, W1 is less than W2. In another embodiment, the width W1 is greater than W2. Each of the widths W1, W2, and other widths referred to herein is the difference between the inner and outer diameters of the electrodes and probes, divided by two. The widths are determined relative to half of the cross-section of the electrodes and probes.

[0045] In the illustrated example, the TES power electrode 216 and the TES probe 218 are positioned such that there is the same gap G1 between i) the TES power electrode 216 and the TES probe 218 and ii) the edge ring 230. The TES power electrode 216 and the TES probe 218 may also be positioned such that i) the gap between the TES power electrode 216 and the edge ring 230 and ii) the gap between the TES probe 218 and the edge ring 230 are different. In this example, the TES power electrode 216 and the TES probe 218 are ring-shaped.

[0046] A gap G2 exists radially between the TES power electrode 216 and the TES probe 218. Gaps G1 and G2 may be adjusted depending on i) the materials of the TES ring 214, the TES power electrode 216, and the TES probe 218, and ii) the voltage applied via the TES power electrode 216. The gap between the TES probe 218 and the edge ring 230 may be minimized to maximize capacitive coupling between the TES probe 218 and the edge ring 230. Gap G2 may be maximized to minimize capacitive coupling between the TES power electrode 216 and the TES probe 218. By having only the radially inner end of the TES probe 218 facing the radially outer end of the TES power electrode 216, the surface area of the TES probe 218 facing the surface of the TES power electrode 216 is minimized. In some embodiments, the amount of capacitive coupling between the TES power electrode 216 and the TES probe 218 is negligibly small.

[0047] As an example, the gaps G1 and G2 may be 1.0 millimeter (mm) or greater. As another example, the gaps G1 and G2 may be 2.0 millimeters (mm) or greater. As another example, the gaps G1 and G2 may each be 3 to 5 millimeters (mm). The gaps G1 and G2 may be the same or different. In one embodiment, the gap between the TES probe 218 and the edge ring 230 is smaller than the gap between the TES power electrode 216 and the edge ring 230. Other examples are provided below. The higher the RF voltage supplied to the TES power electrode 216, the larger the gap G2. The larger the gap G2, the less interference there is between the TES power electrode 216 and the TES probe 218.

[0048] The RF generators 204, 206 generate RF voltage signals that are provided to matching networks 208, 210 and, consequently, to the RF electrode 222 and the TES power electrode 216. The matching networks 208, 210 may include respective pickup sensors 240, 242 that are used to detect the RF voltage and phase of the RF signals output by the RF generators 204, 206.

[0049] Measurement module 212 may be implemented as a printed circuit board (PCB) that includes components for detecting RF voltage and phase via TES probe 218. The RF voltage and phase are provided to controller 202. The RF voltage and phase indicate i) the RF voltage and phase at edge ring 230 and ii) the RF voltage and phase at radially outer edge 250 of substrate 224.

[0050] The controller 202 adjusts the voltage and phase output by the second RF generator 206 and thus applied to the TES probe 218 based on i) the voltage and phase of the RF signal detected by the pickup sensors 240, 242 and ii) the voltage and phase detected via the TES probe 218 and the measurement module 212. The controller 202 may control and adjust the voltage of the RF signal from the second RF generator 206 to i) match the RF voltage at the TES power electrode 216 and / or the RF voltage at the edge ring 230 with the RF voltage at the RF electrode 222 and / or ii) adjust the RF voltage at the edge ring 230 within a set range of the RF voltage of the RF electrode 222. The controller 202 may adjust the RF voltage from the RF generator 206 so that the RF voltage at the TES power electrode 216 and / or the RF voltage at the edge ring 230 is a set amount greater or less than the RF voltage at the RF electrode 222. In one embodiment, the controller 202 is implemented as a proportional-integral-derivative (PID) controller.

[0051] 3 shows a substrate support 300 including an edge ring 302 and an example TES ring 304 with a direct measurement TES probe 306. The edge ring 302 is disposed on the TES ring 304 and surrounds a substrate 308. A cover ring 310 may surround the rings 302, 304 and be disposed on an insulating ring 312. The TES probe 306 may extend vertically through the insulating ring 312 and the TES ring 304 to make direct contact with the edge ring 302.

[0052] The TES ring 304 further includes a TES power electrode 314 embedded in the TES ring 304. The substrate support 300 includes an RF electrode 320. The voltage and phase of the RF signal supplied to the TES power electrode 314 and the RF electrode 320 may be controlled similarly to the voltage and phase of the other TES power electrodes and RF electrodes of the substrate support described herein. This control may be based on the detected RF voltage and phase detected by the TES probe 306.

[0053] A gap G3 exists between the TES power electrode 314 and the edge ring 302. A gap G4 also exists radially between the TES power electrode 314 and the TES probe 306. Gaps G3 and G4 may be adjusted depending on i) the materials of the TES ring 304, the TES power electrode 314, and the TES probe 306, and ii) the voltage applied through the TES power electrode 314. Capacitive coupling between the TES power electrode 314 and the TES probe 306 is minimized because the TES power electrode 314 is ring-shaped and the TES probe 306 is a conductive line positioned to detect the voltage and phase at the detection point. The TES probe 306 extends vertically through the TES ring 304. This arrangement minimizes the surface area of the TES probe 306 facing the radially outer end of the TES power electrode 314. The TES power electrode may have a cross-sectional width W3.

[0054] As an example, the gaps G3 and G4 may be 1.0 millimeters (mm) or more. As another example, the gaps G3 and G4 may be 2.0 millimeters (mm) or more. As another example, the gaps G3 and G4 may be 3 to 5 millimeters (mm). The gaps G3 and G4 may be the same or different.

[0055] 4 shows a substrate support 400 including an edge ring 402 and an example TES ring 404 with an indirect measurement TES probe 406. The edge ring 402 is disposed on the TES ring 404 and surrounds a substrate 408. A cover ring 410 may be disposed on an insulating ring 412 surrounding the rings 402, 404. The TES probe 406 is disposed within the TES ring 404 and connected to a conductor 411 that extends through the insulating ring 412 into the TES ring 404.

[0056] The TES ring 404 further includes a TES power electrode 414 embedded in the TES ring 404 along with a TES probe 406. The TES power electrode 414 and the TES probe 406 may be ring-shaped. The substrate support 400 includes an RF electrode 420. The voltage and phase of the RF signals supplied to the TES power electrode 414 and the RF electrode 420 may be controlled similarly to the voltage and phase of the other TES power electrodes and RF electrodes of the substrate support described herein. This control may be based on the detected RF voltage and phase detected by the TES probe 406. The TES power electrode 414 and the TES probe 406 are capacitively coupled to the edge ring 402.

[0057] A gap G5 exists between the TES power electrode 414 and the edge ring 402. A gap G6 exists between the TES probe 406 and the edge ring 402. The TES probe 406 is vertically offset from the TES power electrode 414, and this gap is referred to as gap G7. A gap G8 also exists radially between the TES power electrode 414 and the TES probe 406. Gaps G5-G8 may be adjusted depending on i) the materials of the TES ring 404, the TES power electrode 414, and the TES probe 406, and ii) the voltage applied via the TES power electrode 414.

[0058] Capacitive coupling between the TES power electrode 414 and the TES probe 406 is minimal because no plane of the TES probe 406 faces the plane of the TES power electrode 414. No plane of the TES probe 406 faces directly across from the plane of the TES power electrode 414. This is due to the vertical offset of the TES probe 406 relative to the TES probe electrode 414 and the non-overlapping arrangement of the TES probe 406 and the TES electrode 414 such that neither the TES probe 406 nor the TES power electrode 414 overlaps horizontally with the other of the TES probe 406 and the TES power electrode 414.

[0059] As an example, each of the gaps G5-G8 may be 1.0 millimeter (mm) or greater. As another example, each of the gaps G5-G8 may be 2.0 millimeters (mm) or greater. As another example, each of the gaps G5-G8 may be 3-5 millimeters (mm). Gap G6 is smaller than gap G5 so that there is stronger capacitive coupling between the TES probe 406 and the edge ring 402.

[0060] The TES power electrode 414 and the TES probe 406 have cross-sectional widths W4 and W5. Widths W4 and W5 may be the same or different. In the illustrated example, width W4 is equal to width W5.

[0061] 5 shows a substrate support 500 including an edge ring 502 and an example TES ring 504 having an indirect measurement TES probe 506 facing the edge ring 502 over a larger surface area than a TES power electrode 508. The edge ring 502 is disposed on the TES ring 504 and surrounds a substrate 509. A cover ring 510 may be disposed on an insulating ring 512 surrounding the rings 502, 504. The TES probe 506 is disposed within the TES ring 504 and connected to a conductor 511 that extends through the insulating ring 512 into the TES ring 504.

[0062] The TES ring 504 includes a TES power electrode 508 embedded in the TES ring 504 along with a TES probe 506. The TES power electrode 508 and the TES probe 506 may be ring-shaped. The substrate support 500 includes an RF electrode 520. The voltage and phase of the RF signals supplied to the TES power electrode 508 and the RF electrode 520 may be controlled similarly to the voltage and phase of the other TES power electrodes and RF electrodes of the substrate support described herein. This control may be based on the detected RF voltage and phase detected by the TES probe 506. The TES power electrode 508 and the TES probe 506 are capacitively coupled to the edge ring 502.

[0063] A gap G9 exists between the TES power electrode 508 and the edge ring 502. A gap G10 exists between the TES probe 506 and the edge ring 502. The TES probe 506 is vertically offset from the TES power electrode 508, and this gap is referred to as gap G11. A gap G12 also exists radially between the TES power electrode 508 and the TES probe 506. Gaps G5-G8 may be adjusted depending on i) the materials of the TES ring 504, the TES power electrode 508, and the TES probe 506, and ii) the voltage applied via the TES power electrode 508.

[0064] Capacitive coupling between the TES power electrode 508 and the TES probe 506 is minimal because no plane of the TES probe 506 faces the plane of the TES power electrode 508. No plane of the TES probe 506 faces directly across from the plane of the TES power electrode 508. This is due to the vertical offset of the TES probe 506 relative to the TES probe electrode 508 and the non-overlapping arrangement of the TES probe 506 and the TES electrode 508 such that neither the TES probe 506 nor the TES power electrode 508 overlaps horizontally with the other of the TES probe 506 and the TES power electrode 508.

[0065] As an example, each of the gaps G9-G12 may be 1.0 millimeter (mm) or greater. As another example, each of the gaps G9-G12 may be 2.0 millimeters (mm) or greater. As another example, each of the gaps G9-G12 may be 3-5 millimeters (mm). The gap G10 is smaller than the gap G9 so that there is stronger capacitive coupling between the TES probe 506 and the edge ring 502.

[0066] The TES power electrode 508 and the TES probe 506 have cross-sectional widths W6 and W7. Width W7 is greater than width W6, resulting in a larger surface area of the TES probe 506 facing the edge ring 502 and thus a stronger capacitive coupling with the edge ring 502. A top planar surface 521 of the TES probe 506 faces a bottom planar surface 522 of the edge ring 502. The top planar surface 521 has a larger surface area than a top planar surface 524 of the TES power electrode 508.

[0067] FIG. 6 shows a TES ring 600 including a ring-shaped TES power electrode 602 with an opening 604 for a direct measurement TES probe 606. A gap G13 exists between the TES power electrode 602 and the TES probe 606. A portion 610 of the body of the TES ring 600 may protrude into the opening 604 to fill the gap G13. The portion 610 may be formed of ceramic and may resist current flow between the TES power electrode 602 and the TES probe 606. The portion 610 minimizes capacitive coupling between the TES power electrode 602 and the TES probe 606. The gap G13 may be greater than 1 mm. In one embodiment, the gap G13 may be greater than 2 mm. In another embodiment, the gap G13 may be between 3 and 5 mm. The gap G13 is set based on i) the materials of the TES ring 600, the TES power electrode 602, and the TES probe 606, and ii) the voltage applied through the TES power electrode 602. The higher the applied voltage, the larger the gap G13. The TES probe 606 is configured to be in direct contact with the edge ring. The TES power electrode 602 is configured to be capacitively coupled to the edge ring.

[0068] 7 shows a TES ring 700 including a ring-shaped TES power electrode 702 and a ring-shaped indirect measurement TES probe 704. The TES power electrode 702 is disposed radially outward of the TES probe 704, with a gap G14 therebetween. Although the TES probe 704 is illustrated as being disposed radially inward of the TES power electrode 702, the TES probe 704 may also be disposed radially outward of the TES power electrode 702. Also, although the width W8 of the TES power electrode 702 is illustrated as being greater than the width W9 of the TES probe, the width W8 may be less than or equal to the width W9.

[0069] The gap G14 may be greater than 1 mm. In one embodiment, the gap G14 may be greater than 2 mm. In another embodiment, the gap G14 may be between 3 and 5 mm. The gap G14 is set based on i) the materials of the TES ring 700, the TES power electrode 702, and the TES probe 704, and ii) the voltage applied via the TES power electrode 702. The higher the applied voltage, the larger the gap G14. The TES power electrode 702 and the TES probe 704 are configured to be capacitively coupled to the edge ring.

[0070] 8A-8B illustrate a method for measuring and controlling edge ring voltage and phase, including diagnostic operations. The method may begin at step 800, where the following steps may be performed by one of the controllers disclosed herein implementing a feedback algorithm for controlling the amplitude and phase of the RF voltage signal at the edge ring. The steps may be performed iteratively. The order of steps provided is an example, and the steps may be performed in a different order. Two or more steps may be performed simultaneously. In step 802, the controller supplies an RF voltage signal via an RF generator and matching network to an RF electrode on the substrate support and to a TES power electrode on the TES ring (e.g., one of the TES power electrodes in FIGS. 1-7).

[0071] In step 804, the controller detects a first RF voltage and a first phase of a first RF signal on an RF electrode of the substrate support via a pickup sensor. In step 806, the controller detects a second RF voltage and a second phase of a second RF signal on the edge ring via a TES probe. The second RF voltage can be a fraction of the RF voltage applied to the TES power electrode. As an example, the voltage applied to the TES power electrode can have an amplitude of 10 kilovolts (kV), and the amplitude of the second RF voltage can be 1.5 to 2 kV.

[0072] In step 808, the controller determines whether the second RF voltage signal is unstable. The stability of the second RF voltage signal is monitored, and based on this information, the controller controls the overall stability of the plasma process. The controller may track voltage fluctuations of the second RF voltage signal and determine that the second RF voltage signal is unstable when the frequency of fluctuations is higher than a set frequency. If unstable, step 810 may be performed; if not, step 812 may be performed.

[0073] In step 810, the controller may adjust the amplitude and / or phase of the RF voltage applied to the TES power electrode to resolve the instability. For example, based on the tracked voltage of the second RF voltage signal, the controller may estimate the amplitude and phase of the second RF voltage signal, compare the amplitude and phase to a target amplitude and phase, and adjust the amplitude and / or phase of the RF voltage signal applied to the TES power electrode based on the difference to maintain the target amplitude and phase at the TES power electrode and / or edge ring. This may include comparing the measured peak-to-peak voltage to a target peak-to-peak voltage and adjusting the RF voltage applied to the TES power electrode based on the difference between the measured peak-to-peak voltage and the target peak-to-peak voltage. The target amplitude, target phase, and target peak-to-peak voltage may be the same as or different from the amplitude, phase, and / or peak-to-peak voltage measured via the RF electrode of the substrate support. As shown in the figure, step 812 may be performed after step 810. In another embodiment, steps 812, 814, 816, and 818 are performed at the same time that steps 808-810 are performed, and step 820 is performed after step 810.

[0074] In step 812, the controller may determine whether the amplitude of the second RF voltage signal is within a first voltage range of the amplitude of the first RF voltage signal and / or a second voltage range of a target amplitude. The target amplitude may be the same as or different from the amplitude of the first RF signal. If not, step 814 may be performed; if not, step 816 may be performed.

[0075] In step 814, the controller may adjust the amplitude of the RF voltage applied to the TES power electrode so that the amplitude of the second RF voltage signal is within a first voltage range of the amplitude of the first RF voltage signal and / or within a second voltage range of the target amplitude.

[0076] In step 816, the controller may determine whether the phase of the second RF voltage signal is within a first phase range of the phase of the first RF phase signal and / or a second phase range of the target phase. The target phase may be the same as or different from the phase of the first RF signal. If not, step 818 may be performed; otherwise, step 820 may be performed.

[0077] In step 818, the controller may adjust the phase of the RF voltage applied to the TES power electrode so that the phase of the second RF voltage signal is within a first phase range of the phase of the first RF voltage signal and / or within a second phase range of the target phase.

[0078] In step 820, the controller determines whether the second RF voltage signal and / or changes in the second RF voltage signal indicate degradation of the state of health (SOH) of the edge ring. As an example, the more frequent the fluctuations and the greater the fluctuations in the second RF voltage signal, the greater the likelihood and extent of degradation of the SOH. Degradation may indicate degradation of the edge ring and / or the TES ring. The edge ring and the TES ring may be replaceable components and may be replaced when they have deteriorated to a set level. As another example, the smaller the amplitude of the second RF voltage signal relative to the amplitude of the first RF voltage signal, the greater the likelihood and extent of degradation of the SOH.

[0079] Drift of RF voltage over time due to degradation may be monitored and tracked. SOH is directly related to drift of RF voltage due to degradation. This allows the controller to compensate for these drifts, for example, due to erosion of the edge ring and / or TES ring. Compensation may include compensating for changes in plasma conditions (such as changes in plasma impedance) due to changes in RF voltage and corresponding phase. If SOH has degraded, step 822 may be performed; otherwise, step 804 may be performed.

[0080] In step 822, the controller may generate a warning message, schedule maintenance, and / or take other corrective action based on the detected SOH degradation. In step 824, the controller may determine whether the SOH is within an acceptable range. If so, step 804 may be performed; if not, step 826 may be performed, and the controller may stop substrate processing and / or prevent the next processing operation from being performed until the edge ring and / or TES ring are replaced. The method may end in step 828.

[0081] The above-described method may include measuring an RF voltage signal at the TES probe to generate a calibration value and correlating the RF voltage signal measured at the RF electrode in the substrate support based on the calibration value. The calibration value may refer to the RF voltage of the TES probe measured when the edge ring and the TES ring are at a new and / or good SOH. The controller may generate the calibration value and adjust the RF voltage signal supplied to the TES power electrode based on the calibration value, the RF voltage signal measured from the RF electrode on the substrate support, and the RF voltage signal measured from the TES probe.

[0082] The above steps are intended to be exemplary. The steps may be performed sequentially, synchronously, simultaneously, consecutively, within overlapping time periods, or in a different order, depending on the application. Also, any of the steps may not be performed or may be skipped, depending on the embodiment and / or the order of events.

[0083] Examples disclosed herein improve etch rate uniformity and ellipticity by measuring and adjusting the amplitude and phase of the voltage at the edge ring to match or set based on the amplitude and phase of the RF electrode in the substrate support. These examples include direct and indirect detection of the edge ring voltage and the phase of the edge ring voltage, allowing targets to be met more easily, resulting in more precise control and less process variability. These examples use capacitive coupling to provide indirect measurement, thereby minimizing and / or eliminating system operation degradation. Matching the amplitude, phase, and / or peak-to-peak voltage at the substrate support to the amplitude, phase, and / or peak-to-peak voltage at the edge ring as disclosed prevents distortion of the plasma sheath near the outer edge of the substrate on the substrate support.

[0084] The foregoing description is merely exemplary in nature and is not intended to limit the disclosure, its applications, or uses. The broad teachings of the present disclosure may be embodied in a variety of forms. Accordingly, while the present disclosure includes specific examples, the true scope of the disclosure is not limited to those examples, as other variations will become apparent from a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be performed in a different order (or simultaneously) without altering the principles of the present disclosure. Furthermore, although each embodiment is described as having particular features, any one or more of the features described with respect to any embodiment of the present disclosure can be implemented in any of the other embodiments and / or combined with any of the features of the other embodiments, even if the combination is not expressly described. In other words, the above-described embodiments are not mutually exclusive, and substituting one or more embodiments for one another is within the scope of the present disclosure.

[0085] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers) are described using various terms, such as "connected," "engaged," "coupled," "adjacent," "adjacent," "on top of," "above," "below," and "disposed." When describing a relationship between first and second elements in this disclosure, unless expressly stated as "direct," the relationship may be a direct relationship where no other intervening elements exist between the first and second elements, or an indirect relationship where one or more intervening elements exist (spatially or functionally) between the first and second elements. As used herein, the phrase "at least one of A, B, and C" should be interpreted to mean the logical (A or B or C) using a non-exclusive logical OR, and not to mean "at least one of A, at least one of B, and at least one of C."

[0086] In some embodiments, the controller is part of a system, which may be part of the examples described above. Such systems may include semiconductor processing equipment, such as one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (e.g., wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronics for controlling the operation of the system before, during, and after processing of semiconductor wafers or substrates. The electronics may be referred to as a "controller" and may control various components or subcomponents of the system. Depending on the processing requirements and / or type of system, the controller may be programmed to control any of the processes disclosed herein, such as supply of process 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 supply settings, position and motion settings, and wafer movement in and out of tools and other transfer tools and / or load locks connected or coupled to the specific system.

[0087] Generally, a controller may be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. 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). Program instructions may be communicated to the controller in the form of various individual settings (or program files) that define operational parameters for performing specific processes on or for semiconductor wafers or instructions for the system. The operational parameters, in some embodiments, may be part of a recipe defined by a process engineer to accomplish one or more process steps during processing of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0088] In some embodiments, the controller may be part of or connected to a computer that is integrated with, connected to, or otherwise networked with the system, or a combination thereof. For example, the controller may be in the “cloud” or may be all or part of a fab host computer system that can enable remote access to wafer processing. The computer may enable remote access to the system to monitor the current progress of a manufacturing operation, examine the history of past manufacturing operations, or examine trends or performance indicators from multiple manufacturing operations, to change parameters of a current process, configure processing steps according to a current process, or initiate a new process. In some examples, a remote computer (e.g., a server) may provide process recipes to the 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 communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, where the instructions 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 being performed as well as the type of tool the controller is configured to interface with or control. Thus, as described above, the controller may be distributed, such as by having one or more separate controllers that are networked and operate toward a common purpose (such as the process and control described herein). One example of a distributed controller for such purposes is one or more integrated circuits on the chamber that communicate with one or more remotely located integrated circuits (e.g., located at the platform level or remotely as part of a remote computer) that cooperate to control the process in the chamber.

[0089] 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 cleaning 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 system that may be associated with or utilized in the fabrication and / or manufacturing of semiconductor wafers.

[0090] As described above, depending on the processing step or steps being performed by the tool, the controller may communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, another controller, or tools used in material transport to carry containers of wafers to or from tool locations and / or load ports within a semiconductor fabrication factory.

Claims

1. 1. A voltage control system comprising: an edge ring disposed on the substrate support and configured to surround an outer periphery of the substrate; 1. An adjustable edge sheath (TES) ring, comprising: a TES power electrode capacitively coupled to the edge ring and configured to receive a first radio frequency (RF) voltage signal; a TES ring comprising: a TES probe electrically coupled to the edge ring and configured to detect a second RF voltage signal at the edge ring; A generator; a controller configured to control the generator to adjust the first RF voltage signal based on the second RF voltage signal; A voltage control system comprising:

2. 10. The voltage control system of claim 1, wherein the TES power electrode and the TES probe are at least partially embedded in the TES ring.

3. 2. The voltage control system of claim 1, wherein the TES power electrode and the TES probe are completely embedded in the TES ring.

4. 2. The voltage control system of claim 1, wherein the TES probe is in direct contact with the edge ring for direct detection of the second RF voltage signal.

5. 2. The voltage control system of claim 1, wherein the TES probe is capacitively coupled to the edge ring for indirect detection of the second RF voltage signal.

6. 2. The voltage control system of claim 1, wherein the edge ring is disposed on and in contact with the TES ring.

7. 2. The voltage control system of claim 1, the TES ring has a bottom surface; A voltage control system, wherein the top surface of the TES probe faces and extends parallel to the bottom surface of the TES ring.

8. 10. The voltage control system of claim 1, wherein at least one of the TES power electrode and the TES probe is ring-shaped.

9. 2. The voltage control system of claim 1, the TES power electrode is ring-shaped; A voltage control system, wherein the TES probe is positioned radially inward or radially outward of the TES power electrode.

10. 10. The voltage control system of claim 9, wherein the TES probe extends vertically and is positioned radially outward of the TES power electrode.

11. 2. The voltage control system of claim 1, the TES power electrode is ring-shaped and has an opening; A voltage control system, wherein a portion of the TES probe extends through the opening.

12. 12. The voltage control system of claim 11, wherein a gap exists between the TES power electrode and the TES probe.

13. 2. The voltage control system of claim 1, the TES power electrode is ring-shaped; A voltage control system, wherein the TES probe is ring-shaped.

14. 14. The voltage control system of claim 13, wherein half the cross-sectional width of the TES probe is greater than half the cross-sectional width of the TES probe.

15. 14. The voltage control system of claim 13, wherein half the cross-sectional width of the TES probe is equal to half the cross-sectional width of the TES probe.

16. 14. The voltage control system of claim 13, wherein half the cross-sectional width of the TES probe is less than half the cross-sectional width of the TES probe.

17. 14. The voltage control system of claim 13, wherein the TES probe is vertically offset from the TES power electrode.

18. 18. The voltage control system of claim 17, wherein the TES probe is positioned closer to the edge ring than the TES power electrode.

19. 2. The voltage control system of claim 1, the TES ring is formed of a dielectric material; a voltage control system, wherein the TES power electrode and the TES probe are embedded in the TES ring such that a portion of the dielectric material is disposed between i) the TES power electrode and the TES probe and ii) the edge ring.

20. 10. The voltage control system of claim 1, further comprising a sensor configured to detect an amplitude and a phase of a third RF voltage signal supplied to an RF electrode of the substrate support; The voltage control system, wherein the controller is configured to adjust the first RF voltage signal based on an amplitude and a phase of the second RF voltage signal and the amplitude and a phase of the third RF voltage signal.

21. 21. The voltage control system of claim 20, wherein the controller is configured to adjust the first RF voltage signal to match the second RF voltage signal in at least one of amplitude and phase to the third RF voltage signal.

22. 10. The voltage control system of claim 1, wherein the controller is configured to determine whether the second RF voltage signal is unstable and to compensate for instability in the second RF voltage signal by adjusting the first RF voltage signal.

23. 2. The voltage control system of claim 1, wherein the controller: determining a health state of at least one of the edge ring or the TES ring based on the second RF voltage signal; A voltage control system configured to determine, based on the health status, at least one of whether to allow processing of the substrate to continue and whether to implement a corrective action.

24. 1. A substrate processing system, comprising: The voltage control system of claim 1; the substrate support provided with an RF electrode; a sensor configured to detect a third RF voltage signal supplied to the RF electrode; Equipped with The controller is configured to adjust the first RF voltage signal based on both the second RF voltage signal and the third RF voltage signal.

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