TW202422628A - Precise feedback control of bias voltage tailored waveform for plasma etch processes - Google Patents

Abstract

A bias electrode and a mid-level electrode are disposed within a substrate support. A lower portion of the substrate support exists between the bias electrode and the mid-level electrode. An upper portion of the substrate support exists between the mid-level electrode and a top surface of the substrate support. A voltage supply system supplies a bias voltage tailored radiofrequency waveform to the bias electrode. A voltage measurement system measures a first voltage on the bias electrode and a second voltage on the mid-level electrode. A controller uses the first voltage, the second voltage, a capacitance of the substrate support lower portion, and a capacitance of the substrate support upper portion to determine a voltage on a top surface of a substrate present on the top surface of the substrate support. The controller conveys the voltage on the top surface of the substrate to the voltage supply system.

Description

Precise feedback control of bias voltage customized waveform for plasma etching process

The present disclosure relates to a substrate support system and an edge ring system for a plasma processing system, and a method of controlling voltage on a substrate, and more particularly to feedback control of a customized waveform of a bias voltage for a plasma processing process.

Plasma processing systems are used to manufacture semiconductor devices such as chips/dies on semiconductor wafers. In a plasma processing system, a semiconductor wafer is exposed to various types of plasma to cause a specified change in the condition of the semiconductor wafer, such as through material deposition and/or material removal and/or material implantation and/or material modification, etc. During plasma processing of a semiconductor wafer, radio frequency (RF) power is delivered through a process gas in a chamber to convert the process gas into plasma when exposed to the semiconductor wafer. Reactive components of the plasma, such as free radicals and ions, interact with materials on the semiconductor wafer to achieve a specified effect on the semiconductor wafer. In some plasma processing systems, a bias voltage is applied at the level of the semiconductor wafer to direct the charged components within the plasma toward the semiconductor wafer.

As the semiconductor industry continues to move toward smaller chip sizes and improved chip performance, it is necessary to use higher density and high aspect ratio features to define transistors on the chip, resulting in transistors that are more sensitive to manufacturing process variations. As the size of features on the chip decreases, certain manufacturing process variations of just a few atoms may require improvements in etch uniformity control. Uniformity of ion flux, ion energy, and ion angular distribution across a semiconductor wafer are stringent requirements for plasma etching and deposition for microelectronics manufacturing. Furthermore, achieving substantially uniform ion flux, ion energy, and ion angular distribution at the edge of a semiconductor wafer is a significant challenge because approximately 10% of the die on a substrate are affected by the results of the manufacturing process occurring within a radial distance of approximately 5 mm from the outer periphery of the semiconductor wafer. It is in this context that many of the embodiments described herein arise.

In an exemplary embodiment, the system includes a bias electrode configured in a substrate support. The substrate support has a top surface configured to support a substrate. The system also includes an intermediate electrode configured in the substrate support such that a lower portion of the substrate support is located between the bias electrode and the intermediate electrode, and such that an upper portion of the substrate support is located between the intermediate electrode and the top surface of the substrate support. The system also includes a voltage supply system connected to supply a bias voltage customized RF waveform to the bias electrode. The system also includes a voltage measurement system connected to measure a first voltage on the bias electrode and a second voltage on the intermediate electrode. The system also includes a controller configured to use the measured first voltage, the measured second voltage, the capacitance of the lower portion of the substrate support, and the capacitance of the upper portion of the substrate support to determine a voltage on the top surface of the substrate when the substrate is present on the top surface of the substrate support. The controller is configured to transmit information about the voltage on the top surface of the substrate to the voltage supply system.

In an exemplary embodiment, a substrate support system for a plasma processing system is disclosed. The substrate support system includes a substrate support having a top surface configured to support a substrate. The substrate support system also includes a bias electrode configured in the substrate support. The bias electrode is configured to control a voltage on the top surface of the substrate. The bias electrode is connected to receive a bias voltage customized RF waveform from a voltage supply system. The bias electrode is configured to electrically receive a first connector for measuring a first voltage on the bias electrode. The substrate support system also includes an intermediate electrode disposed within the substrate support such that a lower portion of the substrate support resides between the bias electrode and the intermediate electrode and an upper portion of the substrate support resides between the intermediate electrode and a top surface of the substrate support. The intermediate electrode is configured to electrically receive a second connector for measuring a second voltage on the intermediate electrode.

In an exemplary embodiment, an edge ring system for a plasma processing system is disclosed. The edge ring system includes an edge ring configured to confine a substrate support. The edge ring system also includes an edge ring electrode configured within the edge ring. The edge ring electrode is configured to control the voltage on the top surface of the edge ring. The edge ring electrode is connected to receive a bias voltage customized RF waveform from a voltage supply system. The edge ring electrode is configured to electrically receive a first connector for measuring a first voltage on the edge ring electrode. The edge ring system also includes an edge ring intermediate electrode disposed in the edge ring so that a lower portion of the edge ring exists between the edge ring electrode and the edge ring intermediate electrode, and an upper portion of the edge ring exists between the edge ring intermediate electrode and a top surface of the edge ring. The edge ring intermediate electrode is configured to electrically receive a second connector for measuring a second voltage on the edge ring intermediate electrode.

In an exemplary embodiment, a method for controlling a voltage on a substrate is disclosed. The method includes operating a voltage supply system to supply a bias voltage custom RF waveform to a bias electrode within a substrate support. The method also includes measuring a first voltage on the bias electrode at a given time. The method also includes measuring a second voltage on an intermediate electrode at a given time. The intermediate electrode is configured within the substrate support so that a lower portion of the substrate support is between the bias electrode and the intermediate electrode, and so that an upper portion of the substrate support is between the intermediate electrode and a top surface of the substrate support. The method also includes using the measured first voltage, the measured second voltage, the capacitance of a lower portion of the substrate support, and the capacitance of an upper portion of the substrate support to determine a voltage on a top surface of the substrate when the substrate is present on the top surface of the substrate support at a given time.

Other embodiments and advantages of the embodiments disclosed herein will become more apparent from the following detailed description and the accompanying drawings.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to those skilled in the art that embodiments of the present disclosure may be implemented without some or all of these specific details. In other respects, well-known process operations are not described in detail in order not to unnecessarily obscure the present disclosure.

1A shows a vertical cross-section through a plasma processing system 100, according to some embodiments. The plasma processing system 100 includes a chamber 101. A coil 109 is disposed above a window 107 of the chamber 101. In many embodiments, the window 107 is formed of a dielectric material such as quartz or other similar material to allow RF power to be transmitted from the coil 109 through the window 107 and into the plasma processing region 102 within the chamber 101. The chamber 101 is electrically connected to a reference ground potential 104. The plasma processing system 100 includes a TCP (transformer coupled plasma) RF generator 113 connected to deliver RF power to the coil 109 via an impedance matching network 111, as shown by connection 115.

The plasma processing system 100 is also configured to provide a controlled flow of a process gas or process gas mixture into the plasma processing region 102, as indicated by arrow 117. As RF power is delivered into and through the plasma processing region 102, the RF power transforms the process gas/mixture exposed to the substrate 105 supported on the substrate support 103 within the chamber 101 into a plasma 119 within the plasma processing region 102. The substrate support 103 has a top surface 103T configured to support the substrate 105 during processing of the top surface 105T of the substrate 105 by the plasma 119 generated above the substrate support 103. In some embodiments, the substrate support 103 is an electrostatic chuck configured to generate an electrostatic force to clamp the substrate 105 to the top surface 103T of the substrate support 103.

In many embodiments, the plasma 119 is generated to cause a controlled change to the substrate 105. In many manufacturing processes, the change to the substrate 105 can be a change in a material or surface condition on the substrate 105. For example, in many manufacturing processes, the change to the substrate 105 can include one or more of etching of a material in the substrate 105, deposition of a material on the substrate 105, implantation of a material into the substrate 105, and/or modification of a material present on the substrate 105. Also, in some embodiments, the plasma 119 is generated in the plasma processing region 102 in the absence of the substrate 105 to provide cleaning of the chamber 101. It should be understood that the plasma processing system 100 may be any type of plasma processing system in which RF power is delivered to the process gas/mixture within the plasma processing region 102 to generate the plasma 119 above the substrate 105 supported on the top surface 103T of the substrate support 103. The plasma processing system 100 is also configured to provide for the removal of gases and process byproduct materials in the plasma processing region 102 via an exhaust system, as indicated by arrow 121.

According to some embodiments, with reference to view A-A in FIG. 1A , FIG. 1B shows a top view of a substrate 105 disposed on a substrate support 103. In some embodiments, the substrate 105 is a semiconductor wafer undergoing a manufacturing process. However, it should be understood that in many embodiments, the substrate 105 can be substantially any type of substrate that is amenable to plasma-based manufacturing processes. For example, in some embodiments, the substrate 105 is formed of silicon, sapphire, GaN, GaAs, or SiC, and/or other substrate materials, and can include a glass panel/substrate, metal foil, metal sheet, polymer material, or the like. Also, in many embodiments, the substrate 105 can vary in form, shape, and/or size. For example, in some embodiments, the substrate 105 is a semiconductor wafer having an outer diameter of 200 mm, 300 mm, 450 mm, or other sizes. Furthermore, in some embodiments, the substrate 105 is a non-circular substrate, such as a rectangular substrate among other shapes used in flat panel displays or the like.

As shown in FIG. 1A , in some embodiments, the bias electrode 123 is disposed within the substrate support 103 below the top surface 103T of the substrate support 103. In some embodiments, the substrate support 103 is formed of a dielectric material, such as a ceramic material or other type of dielectric material, with the bias electrode 123 formed of a conductive material. In some embodiments, the plasma processing system 100 includes a bias RF generator 125 connected to deliver bias RF power to the bias electrode 123 via an impedance matching network 127, as shown by connection 129. The bias electrode 123 is configured to apply a bias voltage to the top surface 105T of the substrate 105 to attract or repel charged components of the plasma 119 toward or away from the substrate 105 .

It should be understood that in various embodiments, the operation of the plasma processing system 100 may include a number of other additional operations, such as controlling the temperature of the substrate 105, and/or applying additional RF power to one or more electrodes disposed within the substrate support 103 to generate additional plasma, among other additional operations. Also, in various embodiments, the plasma processing system 100 is operated according to a specified recipe for a specified schedule to control one or more of the following: the supply of process gas(es) to the plasma processing region 102, the pressure and temperature within the plasma processing region 102, the supply of RF power to the coil 109, the supply of bias RF power to the bias electrode 123, and substantially any other process parameter associated with the operation of the plasma processing system 100.

The bias RF generator 125 is used for biasing the substrate 105 using a sinusoidal waveform voltage. When an RF signal is supplied to the bias electrode 123, the voltage on the top surface 105T of the substrate 105 oscillates periodically at the frequency of the RF signal. This technique for supplying the RF bias voltage to the substrate 105 results in an uncontrolled distribution of the impact ion energy used for etching features on the top surface 105T of the substrate 105. In some embodiments, because the bias RF generator 125 has a one-dimensional control knob for the RF voltage amplitude, the bias RF generator 125 cannot independently control the ion flux incident on the substrate 105. In these embodiments, the ion flux incident on the substrate 105 is determined by the RF power supplied to the coil 109 using the TCP RF generator 113 and by the amplitude of the RF bias voltage on the top surface 105T of the substrate 105, and the amplitude of the RF bias voltage directly affects the energy of the ions incident on the top surface 105T of the substrate 105. In some embodiments, the bias RF generator 125 can adjust the output RF power in either a power adjustment mode or a voltage adjustment mode.

2 shows the voltage on the top surface 105T of the substrate 105 in response to the supply of a fixed amplitude RF voltage to the bias electrode 123 by the bias RF generator 125, with two different ion flux conditions appearing at the top surface 105T of the substrate 105. Curve V(output) 201 represents the fixed amplitude RF voltage supplied to the bias electrode 123 by the bias RF generator 125. Curve V(substrate top 1 Amp) 203 represents the voltage on the top surface 105T of the substrate 105 in response to the supplied RF bias voltage V(output) 201, and has a 1 Amp ion current appearing on the top surface 105T of the substrate 105. Curve V(substrate top 0.5 Amp) 205 represents the voltage on the top surface 105T of the substrate 105 in response to the supplied RF bias voltage V(output) 201, and has a 0.5 Amp ion current appearing on the top surface 105T of the substrate 105. 2 shows that even with a fixed amplitude RF bias voltage supplied to the bias electrode 123 by the bias RF generator 125, the voltage on the top surface 105T of the substrate 105 can vary with the density of the plasma 119 and with the ion flux incident on the substrate 105. Furthermore, the variation in the plasma-induced voltage behavior on the top surface 105T of the substrate 105 creates challenges with respect to the transfer of substrate 105 manufacturing recipes from one processing chamber to another, and with respect to the modification of substrate 105 manufacturing recipes.

According to some embodiments, FIG. 3A shows a vertical cross-sectional view through a plasma processing system 300. The plasma processing system 300 is a variation of the plasma processing system 100 of FIG. 1A. The plasma processing system 300 includes a chamber 101, a window 107, and a plasma processing region 102 within the chamber 101. The plasma processing system 300 also includes a TCP RF generator 113, an impedance matching network 111, a connection 115, and a coil 109 disposed above the window 107. The plasma processing system 300 also provides for the supply of process gases into the plasma processing region 102 as indicated by arrows 117, and the removal of process gases and byproduct materials from the plasma processing region 102 as indicated by arrows 121. RF power supplied from the TCP RF generator 113 through the coil 109 and the RF transparent window 107 to the plasma processing zone 102 transforms the process gas exposed to the substrate 105 into a plasma 119 within the plasma processing zone 102 .

The plasma processing system 300 includes a substrate support 301 that is a variation of the substrate support 103 described with respect to FIG. 1A . The substrate support 301 has a top surface 301T configured to support a substrate 105 during processing. In certain embodiments, the substrate support 301 is an electrostatic chuck configured to generate an electrostatic force to clamp the substrate 105 to the top surface 301T of the substrate support 301. The substrate support 301 also includes a bias electrode 123 disposed within the substrate support 301 below the top surface 301T of the substrate support 301. In some embodiments, the substrate support 301 is formed of a dielectric material such as a ceramic material or other types of dielectric materials, and has a bias electrode 123 formed of a conductive material. In the substrate support 301, the bias electrode 123 is configured to apply a bias voltage to the top surface 105T of the substrate 105 to attract or repel the charged components of the plasma 119 toward or away from the substrate 105.

In the plasma processing system 300, the edge ring 315 surrounds the substrate support 301 such that the top surface 301T of the substrate support 301 is bounded by the edge ring 315. According to some embodiments, referring to the view A-A in FIG. 3A, FIG. 3B shows a top view of the substrate 105 disposed on the substrate support 301 with the edge ring 315 surrounding the substrate support 301. The edge ring electrode 323 is disposed within the edge ring 315. In some embodiments, the edge ring 315 is formed of a dielectric material and has the edge ring electrode 323 formed of a conductive material. In some embodiments, the substrate support 301 extends radially outward below the edge ring 315, such that an outer diameter portion of the substrate support 301 provides a support structure on which the edge ring 315 is disposed. However, regardless of how the edge ring 315 is vertically supported, it should be understood that the edge ring 315 circumscribes the top surface 301T of the substrate support 301.

The bias electrode 123 is electrically connected to the bias voltage supply system 333, as shown by connection 335. The edge ring electrode 323 is also electrically connected to the bias voltage supply system 333, as shown by connection 337. The bias voltage supply system 333 is configured to control the voltage on the bias electrode 123 and the voltage on the edge ring electrode 323. The bias electrode 123 is configured to control the voltage on the top surface 105T of the substrate 105 when the substrate 105 is present on the top surface 301T of the substrate support 301. Due to the presence of a number of materials between the bias electrode 123 and the top surface 105T of the substrate 105, such as a combination of dielectric materials and other materials present above the bias electrode 123 within the substrate support 301, as well as the material of the substrate 105 itself, the voltage applied to the bias electrode 123 may be different from the corresponding voltage on the top surface 105T of the substrate 105. In some embodiments, the material present between the bias electrode 123 and the top surface 105T of the substrate 105 may be electrically represented as a substantially fixed capacitance. The voltage measurement device 311 is connected to measure the voltage on the bias electrode 123, as shown by the connection 313.

In addition to the bias electrode 123, the substrate support 301 also includes an intermediate electrode 302. The intermediate electrode 302 is disposed in the substrate support 301 such that a lower portion 303 of the substrate support 301 is located between the bias electrode 123 and the intermediate electrode 302, and an upper portion 305 of the substrate support 301 is located between the intermediate electrode 302 and a top surface 301T of the substrate support 301. In some embodiments, the intermediate electrode 302 is disposed near where the clamping voltage is applied to clamp the substrate 105 to the substrate support 301. In various embodiments, the intermediate electrode 302 may be configured in different ways. For example, in some embodiments, the intermediate electrode 302 is substantially disk-shaped. In some embodiments, the intermediate electrode 302 has a grating shape. In some embodiments, the intermediate electrode 302 has a spoke shape. In some embodiments, the intermediate electrode 302 is configured as a combination of concentrically spaced annular rings. It should be understood that the intermediate electrode 302 can be configured in substantially any manner as long as the voltage measured on the intermediate electrode 302 represents the voltage that exists across/through the substrate support 301 at the vertical position of the intermediate electrode 302 within the substrate support 301. In some embodiments, one or more clamping electrodes disposed within the substrate support 301 are used as the intermediate electrode 302, wherein a known clamping voltage is applied to the one or more clamping electrodes to generate an electrostatic attraction force to clamp the substrate 105 to the substrate support 301. A voltage measurement device 307 is connected to measure the voltage on the intermediate electrode 302, as shown by connection 309.

The edge ring electrode 323 is configured to control the voltage on the top surface 315T of the edge ring 315. Due to the dielectric material and other materials present in the edge ring 315 above the edge ring electrode 323, the voltage applied to the edge ring electrode 323 can be different from the corresponding voltage on the top surface 315T of the edge ring 315. In some embodiments, the material present between the edge ring electrode 323 and the top surface 315T of the edge ring 315 can be electrically represented as a substantially fixed capacitance. The voltage measurement device 325 is connected to measure the voltage on the edge ring electrode 323, as shown by the connection 327.

In addition to the edge ring electrode 323, the edge ring 315 also includes an edge ring intermediate electrode 317. The edge ring intermediate electrode 317 is disposed within the edge ring 315 such that a lower portion 319 of the edge ring 315 exists between the edge ring electrode 323 and the edge ring intermediate electrode 317, and an upper portion 321 of the edge ring 315 exists between the edge ring intermediate electrode 317 and a top surface 315T of the edge ring 315. The voltage measuring device 329 is connected to measure the voltage on the edge ring intermediate electrode 317, as shown by connection 331. In many embodiments, the edge ring intermediate electrode 317 can be configured in different ways. For example, in some embodiments, the edge ring intermediate electrode 317 is in the shape of an annular ring. In some embodiments, the edge ring intermediate electrode 317 has a grating/strip shape and has one or more annular rings electrically connected to a combination of spaced radially oriented grating/strip structures. In some embodiments, the edge ring intermediate electrode 317 is configured as a combination of concentrically spaced annular rings. It should be understood that the edge ring mid-electrode 317 can be configured in essentially any manner as long as the voltage measured on the edge ring mid-electrode 317 is representative of the voltage that exists across/through the edge ring 315 at the vertical position of the edge ring mid-electrode 317 within the edge ring 315.

According to some embodiments, referring to view B-B in FIG3A , FIG3C shows a top view of the mid-stage electrode 302 in the substrate support 301 and the edge ring mid-stage electrode 317 in the edge ring 315. In some embodiments, the voltage measurement devices 311, 325, 307, and 329 and the associated connections 313, 327, 309, and 331, respectively, are part of a voltage measurement system of a bias voltage supply system 333. In some embodiments, the mid-step electrode 302 in the substrate support 301 and the edge ring mid-step electrode 317 in the edge ring 315 are located at substantially the same vertical height in the plasma processing system 300, such as depicted in FIG3A. However, in some embodiments, the mid-step electrode 302 in the substrate support 301 and the edge ring mid-step electrode 317 in the edge ring 315 are located at different vertical heights in the plasma processing system 300.

According to some embodiments, FIG3D shows a bias voltage supply system 333A that is an exemplary implementation of the bias voltage supply system 333 of FIG3A. The bias electrode 123 and the edge ring electrode 323, together with the electrical connections 335 and 337 associated therewith, respectively, can be considered as components of the bias voltage supply system 333A. The bias voltage supply system 333A includes a voltage supply system 341 having an output electrically connected to a bias voltage supply node 345 via a filter 343, as shown by connections 347 and 349. The voltage supply system 341 is configured to generate a specified bias voltage customized waveform 342 as a function of time at a bias voltage supply node 345. In some embodiments, the specified bias voltage customized waveform 342 includes a bias voltage step portion (Vstep) 342A and a time-varying bias voltage portion (dV/dT) 342B. In some embodiments, the specified bias voltage customized waveform 342 is defined as a continuous series of pulse cycles, where each pulse cycle includes an on period and an off period. The voltage supply system 341 is connected to the controller 351 in a bidirectional data/signal communication manner, and the controller 351 is programmable to direct the operation of the voltage supply system 341 to generate essentially any form of a specified bias voltage customized waveform 342 required for a specific plasma processing operation on the substrate 105.

According to some embodiments, FIG. 3E shows an exemplary implementation of a voltage supply system 341. The voltage supply system 341 includes a first voltage supply 344A and a second voltage supply 344B electrically connected to each other in series so that the output voltages of the two supplies are summed. In some embodiments, each of the first voltage supply 344A and the second voltage supply 344B is a DC voltage supply. The first voltage supply 344A is configured to generate a time-dependent voltage amplitude according to a specified pulse schedule corresponding to the specified bias voltage customized waveform 342. For example, FIG3E shows an exemplary pulse voltage waveform 385 generated and output by the first voltage supply 344A, which will eventually become the bias voltage step portion (Vstep) 342A of the specified bias voltage custom waveform 342. The output of the first voltage supply 344A is electrically connected to the input of the second voltage supply 344B, as shown by electrical connection 383. The output of the second voltage supply 344B is electrically connected to the output of the voltage supply system 341, as shown by electrical connection 347. The second voltage supply 344B is configured to generate a time-varying pulse voltage waveform 387 that will ultimately become a time-varying bias voltage portion (dV/dT) 342B of the specified bias voltage custom waveform 342. In some embodiments, the time-varying pulse voltage waveform 387 varies substantially linearly as a function of the time during the on period of each pulse cycle. Also, in some embodiments, the time-varying pulse voltage waveform 387 increases in amplitude in a substantially linear manner as a function of the time during the on period of each pulse cycle. At the output of the second voltage supply 344B, the pulse voltage waveform 385 is combined with the time-varying pulse voltage waveform 387 to produce the specified bias voltage customized waveform 342. In this way, the output voltage provided by the voltage supply system 341 to the bias voltage supply node 345 is a combination of the pulse voltage waveform 385 generated by the first voltage supply 344A and the pulse voltage waveform 387 generated by the second voltage supply 344B. Each of the first voltage supply 344A and the second voltage supply 344B is connected to the controller 351 in a bidirectional data/signal communication manner, and the controller 351 directs the operation of the first voltage supply 344A and the second voltage supply 344B to synchronize the phase and duty cycle of the pulse voltage waveforms 385 and 387 to generate a specified bias voltage customized waveform 342.

Referring back to FIG. 3D , the bias voltage supply system 333A includes a shunt circuit 353 configured to apply the voltage present on the bias voltage supply node 345 to each of the bias electrode 123 and the edge ring electrode 323 in a controlled manner. The shunt circuit 353 includes a first branch 355 and a second branch 357. The first branch 355 is electrically connected between the bias voltage supply node 345 and the bias electrode 123. The first branch 355 includes a series capacitor 359 and a parallel capacitor 361. In some embodiments, each of the series capacitor 359 and the shunt capacitor 361 is a respective variable capacitor and can each have a capacitance setting that is remotely controlled by means of a controller 351 that is in bidirectional data/signal communication with the shunt circuit 353. In some embodiments, the first branch 355 includes a switching device 360 that is implemented to bypass the series capacitor 359 so that the bias voltage supply node 345 can be switchably electrically connected to the input of the series capacitor 359 or directly connected to the bias electrode 123 by means of the electrical connection 335. In this manner, the switching device 360 is controlled to electrically connect the series capacitor 359 in series between the bias voltage supply node 345 and the bias electrode 123, or to effectively electrically remove the series capacitor 359 from being configured between the bias voltage supply node 345 and the bias electrode 123. Also, in some embodiments, the first branch 355 includes a switching device 362 that implements a parallel capacitor 361 that can be electrically connected to or disconnected from the electrical connection 335, which extends from the output of the first branch 355 to the bias electrode 123. In this way, the switching device 362 is controlled to electrically connect the shunt capacitor 361 between the bias electrode 123 and the reference ground potential 367, or to effectively electrically remove the shunt capacitor 361 from the first branch 355.

The second branch 357 is electrically connected between the bias voltage supply node 345 and the edge ring electrode 323. The second branch 357 includes a series capacitor 363 and a shunt capacitor 365. In some embodiments, each of the series capacitor 363 and the shunt capacitor 365 is a respective variable capacitor and can each have a capacitance setting that is remotely controlled by means of a controller 351 that is in bidirectional data/signal communication with the shunt circuit 353. In some embodiments, the second branch 357 includes a switching device 369 implemented to bypass the series capacitor 363, so that the bias voltage supply node 345 can be switchably electrically connected to the input terminal of the series capacitor 363 or directly connected to the edge ring electrode 323 by way of the electrical connection 337. In this way, the switching device 369 is controlled to electrically connect the series capacitor 363 in series between the bias voltage supply node 345 and the edge ring electrode 323, or to effectively electrically remove the series capacitor 363 from being configured between the bias voltage supply node 345 and the edge ring electrode 323. Also, in some embodiments, the second branch 357 includes a switching device 371 that implements a shunt capacitor 365 that can be electrically connected to or disconnected from an electrical connection 337 that extends from the output of the second branch 357 to the edge ring electrode 323. In this way, the switching device 371 is controlled to electrically connect the shunt capacitor 365 between the edge ring electrode 323 and the reference ground potential 367, or to effectively electrically remove the shunt capacitor 365 from the second branch 357.

In some embodiments, the first branch 355 is configured to disconnect the series capacitor 359 and the parallel capacitor 361, and the second branch 357 is configured to connect the series capacitor 363 and the parallel capacitor 365. More specifically, in these embodiments, the switching devices 360 and 362 are configured to connect the bias voltage supply node 345 directly to the bias electrode 123, and the switching devices 369 and 371 are configured to control the bias voltage transmitted from the bias voltage supply node 345 to the edge ring electrode 323 by the series capacitor 363 and the parallel capacitor 365. Thus, in these embodiments, the bias voltage customized waveform 342 output by the voltage supply system 341 is supplied to the bias electrode 123, and a modified version of the bias voltage customized waveform 342 output by the voltage supply system 341 is supplied to the edge ring electrode 323.

In some embodiments, the first branch 355 is configured so that the series capacitor 359 and the parallel capacitor 361 are connected, and the second branch 357 is configured so that the series capacitor 363 and the parallel capacitor 365 are connected. More specifically, in these embodiments, the switching devices 360 and 362 are configured so that the bias voltage transmitted from the bias voltage supply node 345 to the bias electrode 123 is controlled by the series capacitor 359 and the parallel capacitor 361, and the switching devices 369 and 371 are configured so that the bias voltage transmitted from the bias voltage supply node 345 to the edge ring electrode 323 is controlled by the series capacitor 363 and the parallel capacitor 365. Thus, in these embodiments, a first modified version of the bias voltage customized waveform 342 output by the voltage supply system 341 is supplied to the bias electrode 123, and a second modified version of the bias voltage customized waveform 342 output by the voltage supply system 341 is supplied to the edge ring electrode 323.

Additionally, in some embodiments, series capacitor 359 may be engaged in first branch 355 and shunt capacitor 361 may be disconnected. In some embodiments, shunt capacitor 361 may be engaged in first branch 355 and series capacitor 359 may be disconnected. And, in some embodiments, series capacitor 363 may be engaged in second branch 357 and shunt capacitor 365 may be disconnected. In some embodiments, shunt capacitor 365 may be engaged in second branch 357 and series capacitor 363 may be disconnected.

In some embodiments, a voltage sensor 373, such as a voltage/current flow sensor (VI sensor), is connected to measure the instantaneous voltage on the bias voltage supply node 345 and transmits information about the measured voltage to the controller 351. In some embodiments, a voltage sensor 375, such as a voltage/current flow sensor (VI sensor), is connected to measure the instantaneous voltage at the output of the first branch 355 and transmits information about the measured voltage to the controller 351. In some embodiments, a voltage sensor 377, such as a voltage/current sensor (VI sensor), is connected to measure the instantaneous voltage at the output of the second branch 357 and transmit information about the measured voltage to the controller 351. In many embodiments, the controller 351 is configured to use the voltage measured by one or more of the voltage sensors 373, 375, and 377 as feedback signals (one or more) for controlling the operation of the voltage supply system 341 and one or more of the series capacitor 359, the shunt capacitor 361, the series capacitor 363, and the shunt capacitor 365.

Also, in some embodiments, the bias voltage supply system 333A includes a plurality (N) of RF generators 379-1 to 379-N connected to supply RF bias voltage to the bias voltage supply node 345 via respective impedance matching networks 381-1 to 381-N, where N is greater than or equal to 1. Each of the RF generators 379-1 to 379-N is connected to the controller 351 in bidirectional data/signal communication. At the bias voltage supply node 345, the RF voltage signal (one or more) output by the RF generators 379-1 to 379-N is combined with the bias voltage customized waveform 342 output by the voltage supply system 341. In some embodiments of the bias voltage supply system 333A, RF generators 379-1 to 379-N and corresponding impedance matching networks 381-1 to 381-N are implemented. However, in other embodiments of the bias voltage supply system 333A, RF generators 379-1 to 379-N and corresponding impedance matching networks 381-1 to 381-N are not implemented.

According to some embodiments, FIG. 3F shows an exemplary bias voltage customized waveform 342 generated by a voltage supply system 341, and a corresponding bias voltage waveform 372 on the top surface 105T of the substrate 105, and a corresponding bias voltage waveform 374 on the top surface 315T of the edge ring 315. The bias voltage customized waveform 342 includes a bias voltage step portion (Vstep) 342A and a time-varying bias voltage portion (dV/dT) 342B. The bias voltage customized waveform 342 is generated on a bias voltage supply node 345. Thus, the bias voltage waveform 372 on the top surface 105T of the substrate 105 is based on the bias voltage customized waveform 342 modified by the first branch 355. Similarly, the bias voltage waveform 374 on the top surface 315T of the edge ring 315 is based on the bias voltage customized waveform 342 modified by the second branch 357. The bias voltage waveform 372 includes a step portion 372A and a ramp portion 372B. The bias voltage waveform 374 includes a step portion 374A and a ramp portion 374B.

The shunt capacitor 361 in the first branch 355 controls the amplitude of the step portion 372A of the bias voltage waveform 372 on the top surface 105T of the substrate 105. Specifically, the capacitance setting of the shunt capacitor 361 can be controlled to set the amplitude of the step portion 372A as a percentage (0 to 100%) of the amplitude of the bias voltage step portion (Vstep) 342A. If the parallel capacitor 361 is disconnected (or does not exist) in the first branch 355, the amplitude of the step portion 372A is a fixed percentage of the amplitude of the bias voltage step portion (Vstep) 342A, and depends on the intrinsic capacitance effect of the substrate support 301 and the material of the substrate 105 between the bias electrode 123 and the top surface 105T of the substrate 105. The fixed percentage of the amplitude of the bias voltage step portion (Vstep) 342A is determined by the structure between the output of the voltage supply system 341 and the top surface 105T of the substrate 105. For example, stray shunt capacitance may exist in structures such as filter 343, impedance matching networks 381-1 to 381-N, and electrical connections 347, 349, 345, and 335. Also, when the rise time of the bias voltage step portion (Vstep) 342A is relatively long compared to the ion travel time through the plasma sheath, the series capacitance between the output of the voltage supply system 341 and the top surface 105T of the substrate 105 may reduce the magnitude of the above Vstep 342A by a fixed percentage due to the ion flux during the rise time of Vstep 342A. For example, in some embodiments, multiple series capacitors may be inserted for certain purposes in the filter 343, substrate support 301, substrate 105, and/or electrical connections 347, 349, 345, and 335. The fixed percentage drop in the magnitude of Vstep 342A due to the series capacitors may be largely eliminated by having a relatively short rise time of Vstep 342A, e.g., Vstep << 1 microsecond.

The series capacitor 359 in the first branch 355 controls the slope (voltage variation with respect to time) of the ramp portion 372B of the bias voltage waveform 372 on the top surface 105T of the substrate 105. When voltage is applied to the bias electrode 123, there is an ion current from the plasma 119 toward the top surface 105T of the substrate 105, which discharges the negative charge on the top surface 105T of the substrate 105 and correspondingly causes the magnitude of the negative voltage on the top surface 105T of the substrate 105 to decrease with time. To compensate for the ion-induced decrease in the magnitude of the negative voltage on the top surface 105T of the substrate 105, the time-dependent bias voltage portion (dV/dT) 342B of the bias voltage customized waveform 342 provides a bias voltage increase over time. The capacitance setting of the series capacitor 359 is controlled to tune the variation of the bias voltage as a function of time on the top surface 105T of the substrate 105 to compensate for the ion-induced discharge of the negative charge on the top surface 105T of the substrate 105. In some embodiments, the capacitance setting of the series capacitor 359 is controlled to maintain a substantially constant voltage on the top surface 105T of the substrate 105 during the on period of the bias voltage customized waveform 342. However, in other embodiments, the capacitance setting of the series capacitor 359 is controlled to achieve a desired voltage variation as a function of time (positive dV/dT and/or negative dV/dT) on the top surface 105T of the substrate 105 during the on period of the bias voltage customized waveform 342. If the series capacitor 359 is disconnected/bypassed (or does not exist) in the first branch 355, then the voltage variation as a function of time (dV/dT) on the top surface 105T of the substrate 105 during the on period of the bias voltage customized waveform 342 will track the time-dependent bias voltage portion (dV/dT) 342B of the bias voltage customized waveform 342, and have a fixed voltage amplitude offset based on the intrinsic capacitive effect of the substrate support 301 and the material of the substrate 105 between the bias electrode 123 and the top surface 105T of the substrate 105. In some embodiments, the fixed voltage amplitude offset may also be based on an intrinsic series capacitance between the output of the voltage supply system 341 and the top surface 105T of the substrate 105. In some embodiments, the intrinsic series capacitance corresponds to a plurality of series capacitors inserted in the filter 343, the substrate support 301, the substrate 105, and/or the electrical connections 347, 349, 345, and 335 for some purpose.

The parallel capacitor 365 in the second branch 357 controls the amplitude of the step portion 374A of the bias voltage waveform 374 on the top surface 315T of the edge ring 315. Specifically, the capacitance setting of the parallel capacitor 365 can be controlled to set the amplitude of the step portion 374A as a percentage (0 to 100%) of the amplitude of the bias voltage step portion (Vstep) 342A. If the shunt capacitor 365 is disconnected (or not present) in the second branch 357, the magnitude of the step portion 374A is a fixed percentage of the magnitude of the bias voltage step portion (Vstep) 342A and depends on the intrinsic capacitance effect of the edge ring 315 material between the edge ring electrode 323 and the top surface 315T of the edge ring 315. In some embodiments, the magnitude of the step portion 374A can also be based on the intrinsic series capacitance between the output of the voltage supply system 341 and the top surface 315T of the edge ring 315. In some embodiments, the intrinsic series capacitance described above corresponds to a plurality of series capacitors inserted in the filter 343, the edge ring 315, and/or the electrical connections 347, 349, 345, and 337 for certain purposes.

The series capacitor 363 in the second branch 357 controls the slope (voltage variation with respect to time) of the ramp portion 374B of the bias voltage waveform 374 on the top surface 315T of the edge ring 315. When voltage is applied to the edge ring electrode 323, there is an ion current from the plasma 119 toward the top surface 315T of the edge ring 315, which discharges the negative charge on the top surface 315T of the edge ring 315 and correspondingly causes the magnitude of the negative voltage on the top surface 315T of the edge ring 315 to decrease with time. To compensate for this ion-induced decrease in the magnitude of the negative voltage on the top surface 315T of the edge ring 315, the time-dependent bias voltage portion (dV/dT) 342B of the bias voltage customized waveform 342 provides a bias voltage increase over time. The capacitance setting of the series capacitor 363 is controlled to tune the variation of the bias voltage as a function of time on the top surface 315T of the edge ring 315 to compensate for the ion-induced discharge of the negative charge on the top surface 315T of the edge ring 315. In some embodiments, the capacitance setting of the series capacitor 363 is controlled to maintain a substantially constant voltage on the top surface 315T of the edge ring 315 during the on period of the bias voltage customized waveform 342. However, in other embodiments, the capacitance setting of the series capacitor 363 is controlled to achieve a desired voltage variation as a function of time (positive dV/dT and/or negative dV/dT) on the top surface 315T of the edge ring 315 during the on period of the bias voltage customized waveform 342. If the series capacitor 363 is disconnected/bypassed (or does not exist) in the second branch 357, then the voltage variation as a function of time (dV/dT) on the top surface 315T of the edge ring 315 during the on period of the bias voltage customized waveform 342 will track the time-dependent bias voltage portion (dV/dT) 342B of the bias voltage customized waveform 342, with a fixed voltage amplitude offset based on the intrinsic capacitance effect of the edge ring 315 material between the edge ring electrode 323 and the top surface 315T of the edge ring 315. In some embodiments, the fixed voltage amplitude offset may also be based on an intrinsic series capacitance between the output of the voltage supply system 341 and the top surface 315T of the edge ring 315. In some embodiments, the intrinsic series capacitance corresponds to a plurality of series capacitors inserted in the filter 343, the edge ring 315, and/or the electrical connections 347, 349, 345, and 337 for some purpose.

According to some embodiments, FIG3G shows a bias voltage supply system 333B that is an exemplary implementation of the bias voltage supply system 333 of FIG3A. The bias voltage supply system 333B includes a first voltage supply system 390 and a second voltage supply system 395. The first voltage supply system 390 includes a voltage supply system 391 having an output connected to the bias electrode 123 via a filter 392 and an electrical connection 335. The voltage supply system 391 is configured in the same manner as the voltage supply system 341. Thus, the voltage supply system 391 generates and supplies a specified bias voltage customized waveform 342-1 to the bias electrode 123. The specified bias voltage customized waveform 342-1 includes a step portion 342A1 and a ramp portion 342B1. The filter 392 is configured to prevent the RF signal from entering the voltage supply system 391. In many embodiments, the filter 392 is a low pass filter or a notch filter.

The first voltage supply system 390 also optionally includes a plurality (N) of RF generators 393-1 to 393-N connected to supply RF bias voltage to the bias electrode 123 via respective impedance matching networks 394-1 to 394-N, where N is greater than or equal to 1. Each of the RF generators 393-1 to 393-N is connected in bidirectional data/signal communication with the controller 351. The controller 351 operates to synchronize the bias voltage waveform output by the voltage supply system 391 and each of the RF generators 393-1 to 393-N. The RF voltage signal(s) output by the RF generators 393-1 to 393-N are combined on electrical connection 335 with the bias voltage customized waveform 342-1 output by the voltage supply system 391. The RF generators 393-1 to 393-N and corresponding impedance matching networks 394-1 to 394-N are implemented in some embodiments of the first voltage supply system 390. However, in some embodiments, the RF generators 393-1 to 393-N and corresponding impedance matching networks 394-1 to 394-N are not implemented in the first voltage supply system 390.

The second voltage supply system 395 includes a voltage supply system 396 having an output connected to the edge ring electrode 323 via a filter 397 and an electrical connection 337. The voltage supply system 396 is configured in the same manner as the voltage supply system 341. Thus, the voltage supply system 396 generates and supplies a specified bias voltage customized waveform 342-2 to the edge ring electrode 323. The specified bias voltage customized waveform 342-2 includes a step portion 342A2 and a ramp portion 342B2. The filter 397 is configured to prevent RF signals from entering the voltage supply system 396. In many embodiments, filter 397 is a low pass filter or a notch filter.

The second voltage supply system 395 also optionally includes a plurality (N) of RF generators 398-1 to 398-N connected to supply RF bias voltage to the edge ring electrode 323 via respective impedance matching networks 399-1 to 399-N, where N is greater than or equal to 1. Each of the RF generators 398-1 to 398-N is connected in bidirectional data/signal communication with the controller 351. The controller 351 operates to synchronize the bias voltage waveform output by the voltage supply system 396 and each of the RF generators 398-1 to 398-N. The RF voltage signal(s) output by the RF generators 398-1 to 398-N are combined on electrical connection 337 with the bias voltage custom waveform 342-2 output by the voltage supply system 396. The RF generators 398-1 to 398-N and corresponding impedance matching networks 399-1 to 399-N are implemented in some embodiments of the second voltage supply system 395. However, in some embodiments, the RF generators 398-1 to 398-N and corresponding impedance matching networks 399-1 to 399-N are not implemented in the second voltage supply system 395.

In some embodiments, the bias voltage customized waveform 342-1 is generated to maintain a substantially constant voltage on the top surface 105T of the substrate 105 during the on period of each pulse cycle in the bias voltage customized waveform 342-1, and the bias voltage customized waveform 342-2 is generated to maintain a substantially constant voltage on the top surface 105T of the substrate 105 during the on period of each pulse cycle in the bias voltage customized waveform 342-2. A substantially constant voltage is maintained on the top surface 315T of the edge ring 315 during the period, so that a substantially constant voltage difference is maintained during the parallel on period of the pulse cycles in the bias voltage customized waveforms 342-1 and 342-2, wherein the substantially constant voltage difference is defined to maintain a substantially flat plasma sheath boundary transitioning between the substrate 105 and the edge ring 315. In some embodiments, the step portion 342A1 of the bias voltage customized waveform 342-1 and the step portion 342A2 of the bias voltage customized waveform 342-2 are synchronously controlled to achieve a specified voltage difference between the top surface 105T of the substrate 105 and the top surface 315T of the edge ring 315. Furthermore, in some embodiments, the slope portion 342B1 of the bias voltage customized waveform 342-1 is controlled to compensate for the discharge of negative charges on the top surface 105T of the substrate 105 caused by ions during the on period of each pulse cycle of the bias voltage customized waveform 342-1, so that the voltage on the top surface 105T of the substrate 105 during the on period of each pulse cycle of the bias voltage customized waveform 342-1 remains substantially constant. Furthermore, in some embodiments, the slope portion 342B2 of the bias voltage customized waveform 342-2 is controlled to compensate for the discharge of negative charges on the top surface 315T of the edge ring 315 caused by ions during the on period of each pulse cycle of the bias voltage customized waveform 342-2, so that the voltage on the top surface 315T of the edge ring 315 during the on period of each pulse cycle of the bias voltage customized waveform 342-2 remains substantially constant.

In some embodiments, the controller 351 operates to synchronize the phases of the bias voltage customized waveforms 342-1 and 342-2. In some embodiments, the controller 351 operates to synchronize both the phases and duty cycles of the bias voltage customized waveforms 342-1 and 342-2. In some embodiments, the controller 351 operates to implement a specified phase shift between the bias voltage customized waveforms 342-1 and 342-2. In some embodiments, the bias voltage customized waveforms 342-1 and 342-2 are defined to have different phases and/or different duty cycles relative to each other. And, in some embodiments, one or both of the bias voltage customized waveforms 342-1 and 342-2 are defined to implement a specified step-by-step pulse scheme. It should be understood that the bias voltage customized waveforms 342-1 and 342-2 are separable and independently controllable relative to each other.

Additionally, in many embodiments, any number of voltage sensors, such as voltage/current sensors (VI sensors), may be connected within the bias voltage supply system 333B to measure the real-time voltage at a particular location and transmit information about the measured real-time voltage to the controller 351. In some embodiments, the controller 351 is configured to use the real-time voltage measurements within the first voltage supply system 390 and/or the second voltage supply system 395 to control the operation of any one or more of the voltage supply system 391, the RF generators 393-1 to 393-N, the voltage supply system 396, and the RF generators 398-1 to 398-N.

4 shows an example diagram of a controller 351 according to some embodiments. In some embodiments, the controller 351 includes a processor 409, a storage hardware unit (HU) 411 (e.g., memory), an input HU 401, an output HU 405, an input/output (I/O) interface 403, an I/O interface 407, a network interface controller (NIC) 415, and a data communication bus 413. The processor 409, the storage HU 411, the input HU 401, the output HU 405, the I/O interface 403, the I/O interface 407, and the NIC 415 communicate data with each other via the data communication bus 413. Examples of input HU 401 include a mouse, a keyboard, a stylus, a data acquisition system, a data acquisition card, etc. Examples of output HU 405 include a display, a speaker, a device controller, etc. Examples of NIC 415 include a network interface card, a network adapter, etc. In many embodiments, NIC 415 is configured to operate according to one or more communication protocols and associated physical layers, such as Ethernet and/or EtherCAT, among others. Each of I/O interfaces 403 and 407 is defined to provide compatibility between different hardware units coupled to the I/O interface. For example, I/O interface 403 can be defined to convert signals received from input HU 401 into a format, amplitude, and/or speed compatible with data communication bus 413. Also, the I/O interface 407 may be defined to convert signals received from the data communication bus 413 into a format, amplitude, and/or speed compatible with the output HU 405. Although many operations described herein are performed by the processor 409 of the controller 351, it should be understood that in some embodiments, many operations may be performed by multiple processors of the controller 351 and/or by multiple processors of multiple computing systems connected to the controller 351.

In many embodiments, the plasma processing system 300 is integrated with electronic equipment for controlling the operation of the plasma processing system 300 before, during, and after processing of the substrate 105, wherein the electronic equipment is implemented within a controller 351 configured and connected to control various components and/or sub-components of the plasma processing system 300, including the bias voltage supply system 333. Depending on the substrate 105 processing requirements and/or the specific configuration of the plasma processing system 300, the controller 351 is programmed to control any of the processes and/or components disclosed herein, including the delivery of process gas(es), temperature settings (e.g., heating and/or cooling), pressure settings, vacuum settings, power settings, RF power supply system settings, electronic signal frequency settings, gas flow rate settings, fluid delivery settings, position and operating settings, bias voltage supply system 333 settings, substrate 105 movement into and out of the plasma processing system 300 and/or into and out of a load lock connected to or interfacing with the plasma processing system 300, and the like.

In many embodiments, the controller 351 is defined as an electronic device having integrated circuits, logic, memory, and/or software that directs and controls a variety of tasks/operations, such as receiving instructions, issuing instructions, controlling device operations, performing cleaning operations, performing endpoint measurements, performing metrological measurements (optical, thermal, electrical, etc.), and other tasks/operations, etc. In some embodiments, the integrated circuits within the controller 351 include one or more firmware that stores program instructions, a digital signal processor (DSP), an application specific integrated circuit (ASIC) chip, a programmable logic device (PLD), one or more microprocessors, and/or one or more microcontrollers that execute program instructions (such as software), as well as other computing devices, etc. In some embodiments, program instructions are sent to the controller 351 in the form of a plurality of individual settings (or program files) that define operational parameters for implementing processes on the substrate 105 within the plasma processing system 300. In some embodiments, the operational parameters are included in a recipe defined by a process engineer to perform one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and/or die on the substrate 105.

In some embodiments, the controller 351 is part of or connected to a computer that is integrated with, connected to, or otherwise networked to the plasma processing system 300, or a combination thereof. For example, in some embodiments, the controller 351 is implemented in the “cloud” or is all or part of a wafer fab host computer system, allowing remote access to control of substrate 105 processing by the plasma processing system 300. The controller 351 implements remote access to the plasma processing system 300 to provide monitoring of the current progress of manufacturing operations, to provide a review of the history of previous manufacturing operations, to provide a review of trends or performance metrics in multiple manufacturing operations, to provide changes in processing parameters, to provide settings for subsequent processing steps, to provide specifications for RF power supply system operating parameters, to provide specifications for bias voltage supply system 333 operating parameters, and/or to provide for the initiation of a new substrate manufacturing process.

In some embodiments, a remote computer, such as a server computer system, provides the process recipe to the controller 351 via a computer network, including a local area network and/or the Internet. The remote computer includes a user interface that enables input or programming of parameters and/or settings, which are then transmitted from the remote computer to the controller 351. In some examples, the controller 351 receives instructions in the form of settings for processing the substrate 105 within the plasma processing system 300. It should be understood that the settings are specific to the type of process to be performed on the substrate 105 and the type of tool/device/component that the controller 351 interfaces with or controls. In some embodiments, the controller 351 is distributed, such as by including one or more distributed controllers 351 that are networked together and operate in synchronization for a common purpose, such as operating the plasma processing system 300 to perform a specified process on the substrate 105. Examples of controllers 351 for such purposes include one or more integrated circuits on the chamber that communicate with one or more integrated circuits located remotely (e.g., on a stage level or as part of a remote computer) that combine to control the process in the chamber.

According to some embodiments, FIG5 shows an example of a bias voltage customized waveform 501 supplied to the bias electrode 123 by a bias voltage supply system 333 such as 333A or 333B, and a corresponding voltage waveform 503 generated on the top surface 105T of the substrate 105. The bias voltage customized waveform 501 is similar to the specified bias voltage customized waveform 342 described with respect to FIG3F. Furthermore, the voltage waveform 503 generated on the top surface 105T of the substrate 105 is similar to the bias voltage waveform 372 described with respect to FIG3F. The bias voltage customized waveform 501 has a pulse shape with a cyclic frequency in the RF region. It should be understood that the bias voltage customized waveform 501 is a non-sinusoidal RF waveform. In many embodiments, the bias voltage customized waveform 501 is configured to control the ion energy distribution function (IEDF) of the ions in the plasma 119 within an electrically affected range extending upward from the top surface 105T of the substrate 105. For example, in FIG. 5 , the bias voltage customized waveform 501 is configured to control the IEDF of the ions in the plasma 119 to achieve a substantially monoenergetic ion energy distribution at the top surface 105T of the substrate 105. The bias voltage customized waveform 501 generates a substantially constant negative voltage on the top surface 105T of the substrate 105, as shown by the voltage waveform 503, so that the ions in the plasma 119 are accelerated to substantially the same energy level when they are introduced to the top surface 105T of the substrate 105.

The operation of the bias voltage supply system 333 to generate the bias voltage customized waveform 501 and supply the bias voltage customized waveform 501 to the bias electrode 123 achieves the results of narrow IEDF and independent control of ion energy and ion flux at the top surface 105T of the substrate 105. However, the control of IEDF and ion flux at the top surface 105T of the substrate 105 remains challenging without real-time, in-situ measurement of the IEDF and ion flux at the top surface 105T of the substrate 105. Achieving and maintaining the desired IEDF requires detection of the IEDF or voltage at the top surface 105T of the substrate 105. Because the IEDF depends on the voltage at the top surface 105T of the substrate 105, the real-time IEDF at the top surface 105T of the substrate 105 can be determined by knowing the real-time voltage at the top surface 105T of the substrate 105. However, any direct measurement of the IEDF or voltage at the top surface 105T of the substrate 105 would require the deployment of physical sensors or probes on the substrate 105 which would interfere with the processing of the substrate 105, such as degraded plasma 119 uniformity across the substrate 105, and other issues, and correspondingly lead to reduced semiconductor wafer manufacturing yield. The use of a non-sinusoidal bias voltage custom waveform 501 for control of voltage and current on the substrate 105 depends on knowing the real-time voltage on the top surface 105T of the substrate 105.

Various embodiments are disclosed herein for real-time indirect measurement of voltage on the top surface 105T of the substrate 105 to implement real-time closed-loop feedback control of the non-sinusoidal bias voltage customized waveform 342, 342-1, 501 to achieve and maintain a specified voltage on the top surface 105T of the substrate 105, and accordingly control the IEDF at the top surface 105T of the substrate 105. Efficient and accurate detection of voltage on the top surface 105T of the substrate 105 is important, particularly for plasma-based substrate 105 manufacturing processes that include pulsed operations in which the plasma 119 density changes dynamically within a short time period (e.g., much less than 1 millisecond). Furthermore, this document discloses a number of embodiments for real-time indirect measurement of the voltage on the top surface 315T of the edge ring 315 to implement real-time closed-loop feedback control of the non-sinusoidal bias voltage customized waveforms 342, 342-2, so as to achieve and maintain a specified voltage on the top surface 315T of the edge ring 315, and correspondingly control the IEDF at the top surface 315T of the edge ring 315.

According to some embodiments, FIG6 shows a voltage waveform 601 on the intermediate electrode 302 in the substrate support 301 corresponding to the bias voltage customized waveform 501 supplied to the bias electrode 123 by the bias voltage supply system 333 as shown in FIG5 . FIG6 also shows a voltage waveform 503 generated on the top surface 105T of the substrate 105 from the supply of the bias voltage customized waveform 501 to the bias electrode 123 by the bias voltage supply system 333 as shown in FIG5 . The bias electrode 123 voltage is controlled by the bias voltage customized waveform 342, 342-1, 501 supplied to the bias electrode 123 by the bias voltage supply system 333. The voltage on the top surface 105T of the substrate 105 is controlled by both the bias voltage customized waveform 342, 342-1, 501 supplied to the bias electrode 123 by the bias voltage supply system 333 and the electrons and ions in the plasma 119 incident on the top surface 105T of the substrate 105. The electrically isolated intermediate electrode 302 disposed in the substrate support 301 between the bias electrode 123 and the top surface 301T of the substrate support 301 captures the voltage waveform 601, which is between the bias voltage customized waveform 342, 342-1, 501 and the voltage waveform 503 on the top surface 105T of the substrate 105.

The voltage difference between the bias electrode 123 and the intermediate electrode 302 is proportional to the impedance between the bias electrode 123 and the intermediate electrode 302. Similarly, the voltage difference between the intermediate electrode 302 and the top surface 105T of the substrate 105 is proportional to the impedance between the intermediate electrode 302 and the top surface 105T of the substrate 105. The impedance between the bias electrode 123 and the intermediate electrode 302 is calculated by ( 1/j ω Cintermediate _{to bias electrode} ), where Cintermediate _{to bias electrode} is the capacitance of the lower portion 303 of the substrate support 301 between the bias electrode 123 and the intermediate electrode 302. The impedance between the intermediate electrode 302 and the top surface 105T of the substrate 105 is calculated by ( 1/j ω Csubstrate _{to intermediate} ), where Csubstrate _{to intermediate} is the capacitance of the upper portion 305 of the substrate support 301 between the intermediate electrode 302 and the top surface 301T of the substrate support 301. It is assumed here that the substrate 105 has a negligible effect on the impedance between the mid-stage electrode 302 and the top surface 105T of the substrate 105. Therefore, the electrically isolated mid-stage electrode 302 forms a capacitive voltage divider that picks up a voltage _as shown in Formula 1, where Vmid is the voltage on the mid-stage electrode 302, Vbias _is the voltage on the bias electrode 123, and Vsubstrate _is the voltage on the top surface 105T of the substrate 105. From Formula 1, it follows that the voltage on the mid-stage electrode 302 can be expressed as shown in Formula 2. And, from Formula 1, it follows that the voltage on the top surface 105T of the substrate 105 can be expressed as shown in Formula 3. Therefore, in the case of a known capacitance ( Cmidlevel _{-to-bias-electrode} ) of the lower portion 303 of the substrate support 301 between the bias electrode 123 and the mid-level electrode 302, and in the case of a known capacitance ( Csubstrate _-to-midlevel ) of the upper portion 305 of the substrate support 301 between the mid-level electrode 302 and the top surface 301T of the substrate support 301, and in the case of direct real-time measurement of the voltage on _{the mid-level electrode 302 (Vmidlevel} ) and the voltage on the bias electrode 123 ( Vbias _{- electrode} ), Formula 3 is used to indirectly determine the real-time voltage ( Vsubstrate ) on the top surface 105T of the substrate 105.

Formula 1. =

_Formula 2. Vmid =

_Formula 3. Vsubstrate = Vmidstage ₊ ( Vmid ₋ Vbias _electrode )

The same relationships shown in Equations 1-3 may be applied to the edge ring 315 to indirectly determine the voltage on the top surface 315T of the edge ring 315 by using direct real-time voltage measurements on each of the edge ring electrode 323 and the edge ring intermediate electrode 317 .

The voltage of the edge ring electrode 323 is controlled by the bias voltage customized waveform 342, 342-2 supplied to the edge ring electrode 323 by the bias voltage supply system 333. The voltage on the top surface 315T of the edge ring 315 is controlled not only by the bias voltage customized waveform 342, 342-2 supplied to the edge ring electrode 323 by the bias voltage supply system 333, but also by the electrons and ions in the plasma 119 incident on the top surface 315T of the edge ring 315. The electrically isolated edge ring intermediate electrode 317 disposed in the edge ring 315 between the edge ring electrode 323 and the top surface 315T of the edge ring 315 captures a voltage waveform between the bias voltage custom waveform 342 , 342 - 2 and the voltage waveform on the top surface 315T of the edge ring 315 .

The voltage difference between the edge ring electrode 323 and the edge ring intermediate electrode 317 is proportional to the impedance between the edge ring electrode 323 and the edge ring intermediate electrode 317. Similarly, the voltage difference between the edge ring intermediate electrode 317 and the top surface 315T of the edge ring 315 is proportional to the impedance between the edge ring intermediate electrode 317 and the top surface 315T of the edge ring 315. The impedance between the edge ring electrode 323 and the edge ring middle electrode 317 is calculated by ( 1/jω Cedge ring _{middle to edge ring electrode} ), where Cedge _{ring middle to edge ring electrode} is the capacitance of the lower portion 319 of the edge ring 315 between the edge ring electrode 323 and the edge ring middle electrode 317. The impedance between the edge ring mid-stage electrode 317 and the top surface 315T of the edge ring 315 is calculated by ( 1/j ω C _{edge ring top to edge ring mid-stage} ), where C _{edge ring top to edge ring mid-stage} is the capacitance of the upper portion 321 of the edge ring 315 between the edge ring mid-stage electrode 317 and the top surface 315T of the edge ring 315. Thus, the electrically isolated edge ring mid-stage electrode 317 forms a capacitive voltage divider that picks up a voltage as shown in Equation 4, where Vedge _-ring-mid is the voltage on edge ring mid-stage electrode 317, Vedge _{-ring-electrode} is the voltage on edge ring electrode 323, and Vedge- _ring-top is the voltage on top surface 315T of edge ring 315. From Equation 4, the voltage on edge ring mid-stage electrode 317 can be expressed as shown in Equation 5. And, from Equation 4, the voltage on top surface 315T of edge ring 315 can be expressed as shown in Equation 6. Thus, with a known capacitance ( _{Cedge ring middle to edge ring electrode} ) of the lower portion 319 of the edge ring 315 between the edge ring electrode 323 and the edge ring middle electrode 317, and with a known capacitance ( Cedge ring top to edge ring middle) of the upper portion 321 of the edge ring 315 between the edge ring middle electrode 317 and the top surface 315T of the edge ring 315, and with a voltage ( Cedge _{ring top to edge ring middle} ) on the edge ring middle electrode 317. In the case of direct real-time measurement of the voltage _on the edge ring electrode 323 ( Vedge _{ring electrode} ), the real-time voltage on the top surface 315T of the edge ring 315 ( Vedge _{ring top} ) is indirectly determined using Formula 6.

Formula 4. =

Formula 5. V _{edge ring mid-order} =

Formula 6. V _{edge ring top} = V _{edge ring middle} + ( V _{edge ring middle stage} - V _{edge ring electrode} )

According to some embodiments, FIG7 shows an example of a bias voltage customized waveform 701 supplied to the bias electrode 123 by the bias voltage supply system 333 and a corresponding voltage waveform 703 generated on the top surface 105T of the substrate 105. FIG7 also shows a TCP voltage waveform 705 representing the voltage on the coil 109 resulting from the supply of TCP RF power to the coil 109 by the TCP RF generator 113. In the example of FIG7, RF power is supplied to the TCP coil 109 in a pulsed manner such that consecutive ON pulses of the TCP RF power are separated by OFF pulses of the TCP RF power. The duty cycle of the ON and OFF pulses of the TCP RF power is specified in the plasma processing recipe, i.e., the duration of the ON pulse relative to the duration of the OFF pulse. The supply of the bias voltage customized waveform 701 to the bias electrode 123 is synchronized to coincide with each ON pulse of the TCP RF power supplied to the TCP coil 109.

7 , in the case of a single-step TCP RF power pulse, the plasma 119 undergoes dynamic variations, such as variations in density, in each pulse phase. Thus, even though the bias voltage customized waveform 701 supplied to the bias electrode 123 has a consistent pulse pattern that should produce a consistent pulse pattern in the voltage waveform 703 on the top surface 105T of the substrate 105 during the duration of the ON pulse of the TCP RF power, the dynamic variations in the plasma 119 cause the voltage waveform 703 on the top surface 105T of the substrate 105 to have an initial stabilization time when the bias voltage customized waveform 701 is supplied to the bias electrode 123, as shown in region 707. Specifically, when the bias voltage customized waveform 701 is first supplied to the bias electrode 123 at the beginning of the ON pulse of the TCP RF power to generate the voltage waveform 703 on the top surface 105T of the substrate 105, the density of the plasma 119 is relatively low and the ion flux incident on the substrate 105 is correspondingly low. Therefore, at the beginning of the ON pulse of the TCP RF power, the incident flux of ions on the substrate 105 is not sufficient to electrically neutralize the negative voltage on the top surface 105T of the substrate 105 to achieve the constant set point voltage 711 of the top surface 105T of the substrate 105. As the ON pulse of the TCP RF power continues, the density of the plasma 119 increases to reach a steady state and the ion flux incident on the substrate 105 correspondingly increases to reach a steady state, thereby electrically neutralizing more of the negative voltage on the top surface 105T of the substrate 105 until a constant set point voltage 711 is achieved on the top surface 105T of the substrate 105, as shown in region 709 of the voltage waveform 703.

It is advantageous to control the bias voltage customized waveform 701 supplied to the bias electrode 123 so as to generate the voltage waveform 703 on the top surface 105T of the substrate 105 in a manner that minimizes the initial settling time of the voltage waveform 703 as shown in the region 707. In other words, it is advantageous to control the bias voltage customized waveform 701 supplied to the bias electrode 123 so as to achieve and maintain a constant set point voltage 711 on the top surface 105T of the substrate 105 as the plasma 119 density increases to its steady state condition during the ON pulse of the TCP RF power. In order to control the bias voltage customized waveform 701 supplied to the bias electrode 123 in the manner described above, it is necessary to have a real-time determination of the voltage on the top surface 105T of the substrate 105 as a feedback control signal to the bias voltage supply system 333. The techniques described above with respect to equations 1 to 3 are used to determine the real-time substrate 105 top surface 105T voltage ( Vsubstrate ) via direct measurement of the real-time bias electrode 123 voltage ( Vbias _electrode ) and direct measurement of the real-time mid-level electrode 302 voltage ( Vmid _{- level} ). The determined instantaneous substrate 105 top surface 105T voltage ( Vsubstrate ) is used as a closed-loop feedback control signal for controlling the generation of the bias voltage customized waveform 701 so as to generate the voltage waveform 703 on the top surface 105T of _the substrate 105 in a manner that minimizes the initial settling time of the voltage waveform 703 in order to achieve and maintain a constant set point voltage 711 on the top surface 105T of the substrate 105 as quickly as possible after the initiation of each ON pulse of the TCP RF power.

In certain embodiments, the real-time substrate 105 top surface 105T voltage ( Vsubstrate ) is provided to the bias voltage supply system 333 via the controller 351 for determining the adjustment of the specified bias voltage customized waveform 342 _to be implemented in the next pulse of the specified bias voltage customized waveform 342. It should be understood that substantially any implementation of the specified bias voltage customized waveform 342 can be adjusted as needed to minimize the difference between the feedback signal, i.e., the real-time _{substrate 105 top surface 105T voltage (Vsubstrate} ) , and the constant set point voltage 711. For example, parameters of the specified bias voltage custom waveform 342, such as the initial negative voltage (Vstep), the negative voltage slope (dV/dT), and the duty cycle (the duration of the negative voltage within a given pulse), may be controlled to minimize the difference between the determined instantaneous substrate 105 top surface 105T voltage ( Vsubstrate ) and _the constant set point voltage 711.

It should be understood that the closed loop feedback control method for the voltage generated on the top surface 105T of the substrate 105 as described with respect to Figure 7 can also be applied to control the voltage generated on the top surface 315T of the edge ring 315. Specifically, the techniques described above with respect to equations 4 to 6 are used to determine the voltage ( Vedge _{ring top) of the top surface 315T of the instant edge ring 315 through direct measurement of the voltage (Vedge ring electrode} ) of the instant edge ring electrode 323 and direct measurement of the voltage ( Vedge _{ring middle ) of the instant edge ring} middle electrode 317. The determined instant edge ring 315 top surface 315T voltage ( Vedge _{ring top} ) is used as a closed loop feedback control signal for controlling the generation of a customized waveform of the bias voltage applied to the edge ring electrode 323, so as to generate the voltage waveform on the top surface 315T of the edge ring 315 in a manner that minimizes the initial settling time of the voltage waveform in order to achieve and maintain a constant set point voltage on the top surface 315T of the edge ring 315 as quickly as possible after the initiation of each ON pulse of the TCP RF power.

In some embodiments, the real-time edge ring 315 top surface 315T voltage ( V _{edge ring top} ) is provided to the bias voltage supply system 333 via the controller 351 for determining the adjustment of the specified bias voltage customized waveform 342, 342-2 to be implemented in the next pulse of the specified bias voltage customized waveform 342, 342-2. It should be understood that basically any implementation of the specified bias voltage customized waveform 342, 342-2 can be adjusted as needed to minimize the difference between the feedback signal, that is, the real-time edge ring 315 top surface 315T voltage ( V _{edge ring top} ), and the constant set point voltage. For example, parameters of the specified bias voltage customized waveform 342, 342-2, such as the initial negative voltage (Vstep), the negative voltage slope (dV/dT), and the duty cycle (the duration of the negative voltage within a given pulse) can be controlled to minimize the difference between the determined instant edge ring 315 top 315T voltage ( Vedge _{ring top} ) and the constant set point voltage.

In some embodiments, the voltage on the top surface 315T of the edge ring 315 ( Vedge _{ring top} ) is used to generate a uniform plasma 119 sheath near the edge of the substrate 105 and minimize the impact ion angular distribution function (IADF). In some embodiments, a smaller IADF reduces the tilt effect on the etch profile near the edge of the substrate 105 and thus improves manufacturing yield. In some embodiments, a voltage on a top surface 315T of the edge ring 315 ( Vedge _{ring top ) is compared to a voltage on a top surface 105T of the substrate 105 (Vsubstrate} ) to generate a feedback control signal for reducing a voltage difference between the top surface 105T of the substrate 105 and the top surface 315T of the edge ring 315, wherein the voltage difference causes an undesirable increase in IADF.

According to some embodiments, FIG8 shows a feedback-controlled bias voltage customized waveform 801 supplied to the bias electrode 123 by the bias voltage supply system 333 and a corresponding voltage waveform 803 generated on the top surface 105T of the substrate 105. FIG8 also shows a TCP voltage waveform 805 representing the voltage on the coil 109 generated from the TCP RF power supply to the coil 109 by the TCP RF generator 113. And, for comparison purposes, FIG8 shows the non-feedback-controlled bias voltage customized waveform 701 supplied to the bias electrode 123 in FIG7 and a corresponding voltage waveform 703 generated on the top surface 105T of the substrate 105. FIG8 shows _the determined real-time substrate 105 top surface 105T voltage ( Vsubstrate ) as a feedback signal to implement the use of a constant set point voltage 811 on the top surface 105T of the substrate 105, causing the feedback control bias voltage customized waveform 801 to gradually increase in slope (dV/dT) between consecutive pulses of the feedback control bias voltage customized waveform 801 until the plasma 119 density reaches a steady state during the ON pulse of the TCP RF power.

It should be understood that the closed loop feedback control method for the voltage generated on the top surface 105T of the substrate 105 as described with respect to FIG. 8 can also be applied to control the voltage generated on the top surface 315T of the edge ring 315 . Specifically, the determined real-time edge ring 315 top surface 315T voltage ( Vedge _{ring top} ) is used as a feedback signal to achieve a constant set point voltage on the top surface 315T of the edge ring 315, so that the feedback control bias voltage customized waveform supplied to the edge ring electrode 323 gradually increases in slope (dV/dT) between consecutive pulses of the feedback control bias voltage customized waveform supplied to the edge ring electrode 323 until the plasma 119 density reaches a stable state during the ON pulse of the TCP RF power.

According to some embodiments, FIG9 shows a feedback-controlled bias voltage customized waveform 901 supplied to the bias electrode 123 by the bias voltage supply system 333 and a corresponding voltage waveform 903 generated on the top surface 105T of the substrate 105. FIG9 also shows a TCP voltage waveform 905 representing the voltage on the coil 109 generated from the TCP RF power supply to the coil 109 by the TCP RF generator 113. And, for comparison purposes, FIG9 shows the non-feedback-controlled bias voltage customized waveform 701 supplied to the bias electrode 123 in FIG7 and a corresponding voltage waveform 703 generated on the top surface 105T of the substrate 105. 9 shows _the determined real-time substrate 105 top surface 105T voltage ( Vsubstrate ) as a feedback signal to implement the use of a constant set point voltage 911 on the top surface 105T of the substrate 105, causing the feedback control bias voltage customized waveform 901 to be gradually increased in duty cycle between consecutive pulses of the feedback control bias voltage customized waveform 901 until the plasma 119 density reaches a steady state during the ON pulse of the TCP RF power. The duty cycle of the feedback control bias voltage customized waveform 901 is defined as the percentage of a given pulse of the feedback control bias voltage customized waveform 901 during the application of a negative voltage. The duty cycle of the feedback control bias voltage customized waveform 901 may vary from pulse to pulse of the feedback control bias voltage customized waveform 901. In certain embodiments, such as shown in FIG. 9 , the slope (dV/dT) of the feedback control bias voltage customized waveform 901 is substantially constant during the negative voltage portion of each pulse of the feedback control bias voltage customized waveform 901, regardless of the duty cycle applied during the pulse. However, in some embodiments, the slope (dV/dT) during the negative voltage portion of each pulse of the feedback control bias voltage customized waveform 901 is adjusted between pulses of the feedback control bias voltage customized waveform 901.

In some embodiments, the real-time substrate 105 top surface 105T voltage ( Vsubstrate ) is determined to have _a sufficiently high sampling/measurement rate so that real-time detection is possible when the difference between the real-time substrate 105 top surface 105T voltage ( Vsubstrate ) and _the set point voltage 911 exceeds a specified threshold. In these embodiments, whenever the difference between the real-time substrate 105 top surface 105T voltage ( Vsubstrate ) and _the set point voltage 911 exceeds the specified threshold, the negative voltage portion of the current pulse of the feedback control bias voltage customized waveform 901 is automatically terminated, corresponding to automatic closed-loop feedback control of the duty cycle of the bias voltage customized waveform 901.

In some embodiments, controlling the duty cycle of the bias voltage customized waveform 901 provides for limiting the bias voltage customized waveform 901 within a range extending between an upper voltage boundary and a lower voltage boundary. Also, in some embodiments, controlling the duty cycle of the bias voltage customized waveform 901 provides voltage surge protection based on a control algorithm. Furthermore, controlling the duty cycle of the bias voltage customized waveform 901 provides a direct impact on in-situ ion energy. In many embodiments, any one or more parameters of the bias voltage custom waveform 901 may be feedback controlled to minimize the difference between the determined instantaneous substrate 105 top surface 105T voltage ( Vsubstrate ) and _a constant set point voltage 911 to be achieved and maintained on the top surface 105T of the substrate 105. For example, in some embodiments, _the determined real-time substrate 105 top surface 105T voltage ( Vsubstrate ) is used as a feedback control signal to feedback control one or more of the positive cycle of the bias voltage customized waveform 901, the negative cycle of the bias voltage customized waveform 901, and the frequency of the bias voltage customized waveform 901 so as to achieve and maintain a constant set point voltage 911 on the top surface 105T of the substrate 105.

It should be understood that the closed loop feedback control method for the voltage generated on the top surface 105T of the substrate 105 as described with respect to FIG. 9 is also applicable to controlling the voltage generated on the top surface 315T of the edge ring 315, particularly when implementing the bias voltage supply system 333B of FIG. 3G. Specifically, the determined real-time edge ring 315 top surface 315T voltage ( Vedge _{ring top} ) is used as a feedback signal to achieve a constant set point voltage on the top surface 315T of the edge ring 315, so that the feedback control bias voltage customized waveform supplied to the edge ring electrode 323 is gradually increased over the duty cycle between consecutive pulses of the feedback control bias voltage customized waveform supplied to the edge ring electrode 323 until the plasma 119 density reaches a steady state during the ON pulse of the TCP RF power.

Maintaining a small IADF when pulsing TCP RF power can be challenging due to the capacitance difference between the substrate support 301 and the edge ring 315. Because the edge ring 315 typically has a smaller surface area than the substrate support 301, the edge ring 315 has a smaller capacitance than the substrate support 301. The smaller capacitance of the edge ring 315 results in a larger voltage variation on the top surface 315T of the edge ring 315. Feedback control of the voltage amplitude typically requires more time to adjust for larger deviations from the target voltage. Thus, because the edge ring 315 has a smaller capacitance than the substrate support 301, the edge ring 315 requires faster feedback control than the substrate support 301. When the voltage on the top surface 105T of the substrate 105 or the voltage on the top surface 315T of the edge ring 315 is out of feedback control, a large voltage difference may exist between the top surface 105T of the substrate 105 and the top surface 315T of the edge ring 315, which may cause a large IADF and a corresponding unfavorable etch tilt. In some embodiments, when the bias voltage supply system 333A of FIG. 3D is implemented, closed-loop feedback control of the duty cycle of the bias voltage custom waveform 342 provides a limit on the voltage difference between the top surface 105T of the substrate 105 and the top surface 315T of the edge ring 315 so as to maintain a small IDAF near the edge of the substrate 105. In some embodiments, when the bias voltage supply system 333B of FIG. 3G is implemented, independent closed-loop feedback control of each of the bias voltage customized waveforms 342-1 and 342-2 provides a limit on the voltage difference between the top surface 105T of the substrate 105 and the top surface 315T of the edge ring 315 so as to maintain a small IDAF near the edge of the substrate 105.

In some embodiments, the bias voltage supply system 333 includes a bias electrode 123 disposed in the substrate support 301 and an intermediate electrode 302 disposed in the substrate support 301, such that a lower portion 303 of the substrate support 301 is located between the bias electrode 123 and the intermediate electrode 302, and an upper portion 305 of the substrate support 301 is located between the intermediate electrode 302 and a top surface 301T of the substrate support 301. The bias voltage supply system 333 also includes voltage supply systems 341, 391 connected to supply a bias voltage customized RF waveform to the bias electrode 123. In some embodiments, the bias voltage customized RF waveform is defined as a continuous series of pulse cycles, wherein each pulse cycle includes an on period in which the bias voltage customized RF waveform has a negative voltage and an off period in which the bias voltage customized RF waveform has a positive voltage. The bias voltage supply system 333 also includes a voltage measurement system connected to measure a first voltage on the bias electrode 123 and a second voltage on the intermediate electrode 302. The bias voltage supply system 333 also includes a controller 351 (or a portion of the controller 351), which is configured to use the measured first voltage, the measured second voltage, the capacitance of the lower portion 303 of the substrate support 301, and the capacitance of the upper portion 305 of the substrate support 301 to determine the voltage on the top surface 105T of the substrate 105 when the substrate is present on the top surface 301T of the substrate support 301. The controller 351 is configured to communicate the voltage on the top surface 105T of the substrate 105 to the voltage supply systems 341, 391.

In some embodiments, the voltage supply system 341, 391 is configured to adjust the bias voltage customized RF waveform to minimize the difference between the set point voltage and the voltage on the top surface 105T of the substrate 105. In some embodiments, the voltage supply system 341, 391 is configured to adjust the bias voltage customized RF waveform within a pulse cycle of the bias voltage customized RF waveform. In some embodiments, the controller 351 is configured to determine the voltage on the top surface 105T of the substrate 105 by calculating the sum of a first term and a second term, wherein the first term is equal to the second voltage on the intermediate electrode 302, wherein the second term is equal to the product of a constant and a differential voltage, wherein the constant is equal to the ratio of the capacitance of the lower portion 303 of the substrate support 301 to the capacitance of the upper portion 305 of the substrate support 301, and wherein the differential voltage is equal to the second voltage on the intermediate electrode 302 minus the first voltage on the bias electrode 123.

In some embodiments, the bias voltage supply system 333 also includes an edge ring electrode 323 configured within the edge ring 315, and the edge ring 315 is configured to confine the substrate support 301. The edge ring electrode 323 is configured to control the voltage on the top surface 315T of the edge ring 315. The bias voltage customized RF waveform supplied to the bias electrode 123 in the substrate support 301 is a first bias voltage customized RF waveform. The edge ring electrode 323 is connected to receive a second bias voltage customized RF waveform from the voltage supply system 341, 396. In some embodiments, the second bias voltage customized RF waveform is defined as a continuous series of pulse cycles, wherein each pulse cycle includes an on period in which the second bias voltage customized RF waveform has a negative voltage and an off period in which the second bias voltage customized RF waveform has a positive voltage. The bias voltage supply system 333 also includes an edge ring intermediate electrode 317 configured in the edge ring 315, so that the lower portion 319 of the edge ring 315 exists between the edge ring electrode 323 and the edge ring intermediate electrode 317, and the upper portion 321 of the edge ring 315 exists between the edge ring intermediate electrode 317 and the top surface 315T of the edge ring 315.

The voltage measurement system is connected to measure a third voltage on the edge ring electrode 323 and a fourth voltage on the edge ring intermediate electrode 317. The controller 351 is configured to use the measured third voltage on the edge ring electrode 323, the measured fourth voltage on the edge ring intermediate electrode 317, the capacitance of the lower portion 319 of the edge ring 315, and the capacitance of the upper portion 321 of the edge ring 315 to determine the voltage on the top surface 315T of the edge ring 315. In some embodiments, the controller 351 is configured to determine the voltage on the top surface 315T of the edge ring 315 by calculating the sum of a first term and a second term, wherein the first term is equal to the fourth voltage on the edge ring mid-stage electrode 317, wherein the second term is equal to the product of a constant and a differential voltage, wherein the constant is equal to the ratio of the capacitance of the lower portion 319 of the edge ring 315 to the capacitance of the upper portion 321 of the edge ring 315, and wherein the differential voltage is equal to the fourth voltage on the edge ring mid-stage electrode 317 minus the third voltage on the edge ring electrode 323. The controller 351 is configured to transmit the voltage on the top surface 315T of the edge ring 315 to the voltage supply system.

In some embodiments, the bias voltage supply system 333 includes variable capacitors 359, 361, 363, 365, which are configured to individually control the second bias voltage customized RF waveform supplied to the edge ring electrode 323 relative to the first bias voltage customized RF waveform supplied to the bias electrode 123. In some embodiments, the voltage supply system 341, 396 is configured to adjust the second bias voltage customized RF waveform supplied to the edge ring electrode 323 to minimize the difference between the set point voltage and the voltage on the top surface 315T of the edge ring 315. In some embodiments, the voltage supply system 341, 396 is configured to adjust the second bias voltage customized RF waveform supplied to the edge ring electrode 323 within a pulse cycle of the second bias voltage customized RF waveform.

In certain embodiments, a substrate support system for a plasma processing system 300 is disclosed. The substrate support system includes a substrate support 301 having a top surface 301T configured to support a substrate 105. The substrate support system includes a bias electrode 123 disposed within the substrate support 301. The bias electrode 123 is configured to control a voltage on a top surface 105T of the substrate 105. The bias electrode 123 is connected to receive a bias voltage customized RF waveform from a voltage supply system 341, 391. The substrate support system also includes an intermediate electrode 302 disposed within the substrate support 301 such that a lower portion 303 of the substrate support 301 is located between the bias electrode 123 and the intermediate electrode 302, and an upper portion 305 of the substrate support 301 is located between the intermediate electrode 302 and a top surface 301T of the substrate support 301. The substrate support system also includes a first connector 313 electrically connected to the bias electrode 123 for measuring a first real-time voltage on the bias electrode 123. The bias electrode 123 is configured to electrically receive the first connector 313 for measuring the first real-time voltage on the bias electrode 123. The substrate support system also includes a second connector 309 electrically connected to the intermediate electrode 302 for measuring a second real-time voltage on the intermediate electrode 302. The intermediate electrode 302 is configured to electrically receive the second connector 309 for measuring the second real-time voltage on the intermediate electrode 302. The substrate support system also includes a controller 351, which is configured to use the measured first real-time voltage on the bias electrode 123, the measured second real-time voltage on the intermediate electrode 302, the capacitance of the lower portion 303 of the substrate support 301, and the capacitance of the upper portion 305 of the substrate support 301 to determine the real-time voltage on the top surface 105T of the substrate 105.

In certain embodiments, an edge ring system for a plasma processing system 300 is disclosed. The edge ring system includes an edge ring 315 configured to confine a substrate support 301. The edge ring system also includes an edge ring electrode 323 configured within the edge ring 315. The edge ring electrode 323 is configured to control a voltage on a top surface 315T of the edge ring 315. The edge ring electrode 323 is connected to receive a bias voltage custom RF waveform from a voltage supply system 341, 396. The edge ring system also includes an edge ring intermediate electrode 317 disposed in the edge ring 315 such that a lower portion 319 of the edge ring 315 exists between the edge ring electrode 323 and the edge ring intermediate electrode 317, and an upper portion 321 of the edge ring 315 exists between the edge ring intermediate electrode 317 and a top surface 315T of the edge ring 315. The edge ring system also includes a first connector 327 electrically connected to the edge ring electrode 323 for measuring a first real-time voltage on the edge ring electrode 323. The edge ring electrode 323 is configured to electrically receive the first connector 327 for measuring a first real-time voltage on the edge ring electrode 323. The edge ring system also includes a second connector 331 electrically connected to the edge ring intermediate electrode 317 for measuring a second real-time voltage on the edge ring intermediate electrode 317. The edge ring intermediate electrode 317 is configured to electrically receive the second connector 331 for measuring a second real-time voltage on the edge ring intermediate electrode 317. The controller 351 is configured to use the measured first real-time voltage on the edge ring electrode 323, the measured second real-time voltage on the edge ring middle electrode 317, the capacitance of the lower portion 319 of the edge ring 315, and the capacitance of the upper portion 321 of the edge ring 315 to determine the real-time voltage on the top surface 315T of the edge ring 315.

According to some embodiments, FIG. 10A shows a flow chart of a method for controlling voltage on a substrate 105. The method includes operation 1001 for operating a voltage supply system 341, 391 to supply a bias voltage customized RF waveform to a bias electrode 123 in a substrate support 301. The method also includes operation 1003 for measuring a first voltage on the bias electrode 123 at a given time. It should be understood that other related parameters may be used to determine/calculate a variety of electrical parameters such as voltage, for example, V=IR, where V is voltage, I is current, and R is resistance. Thus, it should be understood that the various voltage measurements mentioned herein can be performed by direct voltage measurement or indirect voltage measurement, wherein the indirect voltage measurement includes the determination/measurement of one or more parameters related to the voltage to be measured and the subsequent determination/calculation of the voltage to be measured using one or more parameters related to the voltage to be measured. The method also includes operation 1005 for measuring a second voltage on the intermediate electrode 302 at a given time. The method also includes an operation 1007 for using a first voltage on the bias electrode 123 measured at a given time, a second voltage on the intermediate electrode 302 measured at a given time, a capacitance of a lower portion 303 of the substrate support 301, and a capacitance of an upper portion 305 of the substrate support 301 to determine a voltage on a top surface 105T of the substrate 105 when the substrate 105 is present on a top surface 301T of the substrate support 301 at the given time.

According to certain embodiments, FIG. 10B shows a flow chart of an optional continuation of the method of FIG. 10A for controlling a voltage on a substrate 105. The method includes an operation 1009 for determining a difference between a voltage on a top surface 105T of the substrate 105 at a given time and a set point voltage. The method also includes an operation 1011 for determining an adjustment to a bias voltage custom RF waveform that will reduce the difference between a voltage on a top surface 105T of the substrate 105 at a given time and the set point voltage. The method also includes an operation 1013 for operating a voltage supply system 341, 391 to implement the adjustment to the bias voltage custom RF waveform.

In some embodiments, the given time occurs during a negative portion of a cycle of the bias voltage customized RF waveform, and operation 1013 is performed to implement an adjustment to the bias voltage customized RF waveform during the negative portion of a cycle under the bias voltage customized RF waveform. In some embodiments, the adjustment to the bias voltage customized RF waveform is a change in voltage as a function of time during the negative portion of a cycle under the bias voltage customized RF waveform. In some embodiments, the adjustment to the bias voltage customized RF waveform is a change in the duration of the negative portion of a cycle under the bias voltage customized RF waveform.

According to some embodiments, FIG. 10C shows a flow chart of an optional continuation of the method of FIG. 10A or FIG. 10B. The method also includes an operation 1015 for operating the voltage supply system 341, 396 to supply a second bias voltage customized RF waveform to the edge ring electrode 323 within the edge ring 315 of the confined substrate support 301. In this embodiment, the bias voltage customized RF waveform supplied to the bias electrode 123 in the substrate support 301 is referred to as the first bias voltage customized RF waveform. The method also includes an operation 1017 for measuring a third voltage on the edge ring electrode 323 at a given time. The method also includes an operation 1019 for measuring a fourth voltage on the edge ring intermediate electrode 317 at a given time. The method also includes an operation 1021 for using the third voltage on the edge ring electrode 323 measured at a given time, the fourth voltage on the edge ring intermediate electrode 317 measured at a given time, the capacitance of the lower portion 319 of the edge ring 315, and the capacitance of the upper portion 321 of the edge ring 315 to determine the voltage on the top surface 315T of the edge ring 315 at a given time.

According to certain embodiments, FIG. 10D shows a flow chart of an optional continuation of the method of FIG. 10C for controlling the voltage on the edge ring 315. The method includes an operation 1023 for determining the difference between the voltage on the top surface 315T of the edge ring 315 at a given time and the set point voltage. The method also includes an operation 1025 for determining an adjustment for the second bias voltage custom RF waveform that will reduce the difference between the voltage on the top surface 315T of the edge ring 315 at a given time and the set point voltage. The method also includes an operation 1027 for operating the voltage supply system 341, 396 to implement the adjustment for the second bias voltage custom RF waveform. In some embodiments, the given time occurs during a negative portion of a cycle of the second bias voltage customized RF waveform, and operation 1027 is performed to implement an adjustment to the second bias voltage customized RF waveform during the negative portion of a cycle under the second bias voltage customized RF waveform. In some embodiments, the adjustment to the second bias voltage customized RF waveform is a voltage change as a function of time during the negative portion of a cycle under the second bias voltage customized RF waveform. In some embodiments, the adjustment of the second bias voltage customized RF waveform is a change in the duration of a negative segment of a cycle under the second bias voltage customized RF waveform.

The embodiments described herein may be practiced in conjunction with a variety of computer system configurations, including handheld hardware units, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers, and the like. The embodiments described herein may also be practiced in conjunction with a distributed computing environment in which remote processing hardware units connected via a computer network perform tasks. It should also be understood that the embodiments disclosed herein include the execution of a variety of computer-implemented operations involving data stored in a computer system. These computer-implemented operations are operations that manipulate physical quantities. In many embodiments, the computer-implemented operations are performed by a general-purpose computer or a special-purpose computer. In some embodiments, the computer is operated by executing selectively activated computers and/or by directing one or more computer programs stored in the computer memory or obtained via a computer network. When the computer program and/or digital data are obtained via a computer network, the digital data can be processed by other computers on the computer network, for example, a computing resource cloud. The computer program and digital data are stored as computer-readable code on non-transitory computer-readable media. Non-transitory computer-readable media is any data storage hardware unit that stores data, such as a memory device, etc., and the data can then be read by a computer system. Examples of non-transitory computer-readable media include hard disks, network attached storage (NAS), ROM, RAM, compact disk-ROMs (CD-ROMs), recordable CDs (CD-Rs), rewritable CDs (CD-RWs), digital video/optical disks (DVDs), magnetic tapes, and other optical and non-optical data storage hardware units. In some embodiments, a computer program and/or digital data is distributed among multiple computer-readable media located in different computer systems in a network of coupled computer systems, so that the computer program and/or digital data can be executed and/or stored in a distributed form.

Although the above disclosure includes certain details for the purpose of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. For example, it is understood that one or more features of any embodiment disclosed herein may be combined with one or more features of any other embodiment disclosed herein. Therefore, the embodiments herein should be regarded as illustrative and not restrictive, and the scope of the claims is not limited to the details given herein, but may be modified within the scope of the embodiments and equivalents.

100,300: Plasma processing system 101: Chamber 102: Plasma processing zone 103: Substrate support 103T: Top surface of substrate support 103 104: Reference ground potential 105: Substrate 105T: Top surface of substrate 107: Window 109: Coil 111,127: Impedance matching network 113: TCP RF generator 115,129,309,327,313,331,335,337,347,349: Connections 117,121: Arrows 119: Plasma 123: Bias electrode 125: Bias RF generator 201: Curve V (output) 203: Curve V (1 Amp at the top of the substrate) 205: Curve V (0.5 Amp at the top of the substrate) 301: Substrate support 301T: Top surface of substrate support 301 302: Intermediate electrode 303: Lower portion of substrate support 301 305: Upper portion of substrate support 301 307,311,325,329: Voltage measuring device 315: Edge ring 315T: Top surface of edge ring 315 317: Intermediate electrode of edge ring 319: Lower portion 319 of edge ring 315 321: Upper part of edge ring 315 323: Edge ring electrode 333,333A,333B: Bias voltage supply system 341,391,396: Voltage supply system 342,342-1,342-2: Custom waveform for specifying bias voltage 342A: Bias voltage step portion (Vstep) 342B: Time-dependent bias voltage portion (dV/dT) 342A1,342A2: Step portion 342B1,342B2: Slope portion 343,392,397: Filter 344A: First voltage supply 344B: second voltage supply 345: bias voltage supply node 351: controller 353: shunt circuit 355: first branch 357: second branch 359,363: series capacitor 360,362,369,371: switching device 361,365: parallel capacitor 367: reference ground potential 372: corresponding bias voltage waveform on the top surface 105T of the substrate 105 372A: step portion 372B: ramp portion 374: corresponding bias voltage waveform on the top surface 315T of the edge ring 315 374A: step portion 374B: ramp section 373,375,377: voltage sensor 379-1 … 379-N, 393-1 … 393-N, 398-1 … 398-N: RF generator 381-1 … 381-N, 394-1 … 394-N, 399-1 … 399-N: impedance matching network 383: electrical connection 385: pulse voltage waveform 387: time-dependent pulse voltage waveform 390: first voltage supply system 395: second voltage supply system 401: input HU 403: input/output (I/O) interface 405: output HU 407: I/O interface 409: Processor 411: Storage hardware unit (HU) 413: Data communication bus 415: Network interface controller (NIC) 501,701: Bias voltage custom waveform 503,703,803,903: Corresponding voltage waveform 601,705,805,905: Voltage waveform 707,709: Region of waveform 703 711,811,911: Constant set point voltage 801,901: Feedback control bias voltage custom waveform 1001,1003,1005,1007,1009,1011,1013,1015,1017,1019,1021,1023,1025,1027: Operation

According to some embodiments, FIG. 1A shows a vertical cross-section through a plasma processing system.

According to some embodiments, referring to view A-A in FIG. 1A , FIG. 1B shows a top view of a substrate disposed on a substrate support.

2 shows the voltage on the top surface of the substrate in response to the supply of a fixed amplitude RF voltage to the bias electrode by the bias RF generator, with two different ion flux conditions occurring at the top surface of the substrate, according to some embodiments.

According to some embodiments, FIG. 3A shows a vertical cross-section through a plasma processing system.

According to some embodiments, referring to view A-A in FIG. 3A , FIG. 3B shows a top view of a substrate disposed on a substrate support having an edge ring surrounding the substrate support.

According to some embodiments, referring to view plane B-B in FIG. 3A , FIG. 3C shows a top view of a mid-level electrode in a substrate support and a mid-level electrode in an edge ring in an edge ring.

According to some embodiments, FIG. 3D shows a bias voltage supply system that is an exemplary implementation of the bias voltage supply system of FIG. 3A .

According to some embodiments, FIG. 3E shows an exemplary implementation of a voltage supply system within the bias voltage supply system of FIG. 3D .

According to some embodiments, FIG. 3F shows an exemplary bias voltage customized waveform generated by the voltage supply system of FIG. 3E , and a corresponding bias voltage waveform on the top surface of the substrate, and a corresponding bias voltage waveform on the top surface of the edge ring.

According to some embodiments, FIG. 3G shows a bias voltage supply system that is an exemplary implementation of the bias voltage supply system of FIG. 3A .

FIG. 4 shows an example diagram of a controller according to some embodiments.

FIG. 5 shows an example of a bias voltage customized waveform supplied to a bias electrode by the bias voltage supply system of FIG. 3A and a corresponding voltage waveform generated on a top surface of a substrate, according to some embodiments.

According to some embodiments, FIG. 6 shows a voltage waveform on an intermediate electrode in a substrate support corresponding to the customized waveform of the bias voltage supplied to the bias electrode by the bias voltage supply system as shown in FIG. 5 .

According to some embodiments, FIG. 7 shows an example of a bias voltage customized waveform supplied to a bias electrode by the bias voltage supply system of FIG. 3A and a corresponding voltage waveform generated on a top surface of a substrate.

According to some embodiments, FIG. 8 shows a feedback-controlled bias voltage customized waveform supplied to a bias electrode by the bias voltage supply system of FIG. 3A and a corresponding voltage waveform generated on a top surface of a substrate.

FIG. 9 illustrates another feedback-controlled bias voltage customized waveform supplied to a bias electrode by the bias voltage supply system of FIG. 3A and a corresponding voltage waveform generated on a top surface of a substrate, according to some embodiments.

According to some embodiments, FIG. 10A shows a flow chart of a method for controlling a voltage on a substrate.

According to some embodiments, FIG. 10B shows a flow chart of an optional continuation of the method of FIG. 10A for controlling a voltage on a substrate.

According to some embodiments, FIG. 10C is a flow chart showing an optional continuation of the method of either FIG. 10A or FIG. 10B .

According to some embodiments, FIG. 10D shows a flow chart of an optional continuation of the method of FIG. 10C for controlling the voltage on the edge ring.

Claims (25)

A system for controlling a voltage on a substrate comprises: a bias electrode disposed in a substrate support having a top surface configured to support a substrate; an intermediate electrode disposed in the substrate support such that a lower portion of the substrate support is located between the bias electrode and the intermediate electrode, and an upper portion of the substrate support is located between the intermediate electrode and the top surface of the substrate support; a voltage supply system connected to supply a bias voltage customized RF waveform to the bias electrode; a voltage measurement system connected to measure a first voltage on the bias electrode and a second voltage on the intermediate electrode; and a controller configured to use the measured first voltage, the measured second voltage, the capacitance of the lower portion of the substrate support, and the capacitance of the upper portion of the substrate support to determine a voltage on a top surface of the substrate when the substrate is present on the top surface of the substrate support, the controller being configured to transmit information about the voltage on the top surface of the substrate to the voltage supply system. A system as in claim 1, wherein the bias voltage customized RF waveform is defined as a continuous series of pulse cycles, each pulse cycle including an on period in which the bias voltage customized RF waveform has a negative voltage and an off period in which the bias voltage customized RF waveform has a positive voltage. A system as in claim 2, wherein the voltage supply system is configured to adjust the bias voltage custom RF waveform to minimize a difference between a set point voltage and the voltage on the top surface of the substrate. A system as in claim 3, wherein the voltage supply system is configured to adjust the bias voltage customized RF waveform within a pulse cycle of the bias voltage customized RF waveform. A system as in claim 1, wherein the controller is configured to determine the voltage on the top surface of the substrate by calculating the sum of a first term and a second term, wherein the first term is equal to the second voltage, wherein the second term is equal to a product of a constant and a differential voltage, wherein the constant is equal to a ratio of the capacitance of the lower portion of the substrate support to the capacitance of the upper portion of the substrate support, and wherein the differential voltage is equal to the second voltage minus the first voltage. The system of claim 1 further comprises: an edge ring electrode disposed in an edge ring, the edge ring being configured to confine the substrate support, the edge ring electrode being configured to control a voltage on a top surface of the edge ring, wherein the bias voltage customized RF waveform supplied to the bias electrode in the substrate support is a first bias voltage customized RF waveform, and the edge ring electrode is connected to receive a second bias voltage customized RF waveform from the voltage supply system; and An edge ring intermediate electrode is arranged in the edge ring so that a lower portion of the edge ring exists between the edge ring electrode and the edge ring intermediate electrode, and an upper portion of the edge ring exists between the edge ring intermediate electrode and the top surface of the edge ring, wherein the voltage measurement system is connected to measure a third voltage on the edge ring electrode and a fourth voltage on the edge ring intermediate electrode, The controller is configured to use the measured third voltage, the measured fourth voltage, the capacitance of the lower portion of the edge ring, and the capacitance of the upper portion of the edge ring to determine the voltage on the top surface of the edge ring, and the controller is configured to transmit information about the voltage on the top surface of the edge ring to the voltage supply system. The system of claim 6 further comprises: A variable capacitor configured to individually control the second bias voltage customized RF waveform relative to the first bias voltage customized RF waveform. A system as in claim 6, wherein the second bias voltage customized RF waveform is defined as a continuous series of pulse cycles, wherein each pulse cycle includes an on period in which the second bias voltage customized RF waveform has a negative voltage and an off period in which the second bias voltage customized RF waveform has a positive voltage. A system as in claim 8, wherein the voltage supply system is configured to adjust the second bias voltage customized RF waveform to minimize a difference between a set point voltage and the voltage on the top surface of the edge ring. The system of claim 9, wherein the voltage supply system is configured to adjust the second bias voltage customized RF waveform within a pulse cycle of the second bias voltage customized RF waveform. A system as in claim 7, wherein the controller is configured to determine the voltage on the top surface of the edge ring by calculating the sum of a first term and a second term, wherein the first term is equal to the fourth voltage, wherein the second term is equal to a product of a constant and a differential voltage, wherein the constant is equal to a ratio of the capacitance of the lower portion of the edge ring to the capacitance of the upper portion of the edge ring, and wherein the differential voltage is equal to the fourth voltage minus the third voltage. A substrate support system for a plasma processing system, comprising: a substrate support having a top surface configured to support a substrate; a bias electrode disposed in the substrate support, the bias electrode being configured to control a voltage on a top surface of the substrate, the bias electrode being connected to receive a bias voltage customized RF waveform from a voltage supply system, wherein the bias electrode is configured to electrically receive a first connector for measuring a first voltage on the bias electrode; and An intermediate electrode is disposed in the substrate support so that a lower portion of the substrate support is located between the bias electrode and the intermediate electrode, and an upper portion of the substrate support is located between the intermediate electrode and the top surface of the substrate support, wherein the intermediate electrode is configured to electrically receive a second connector for measuring a second voltage on the intermediate electrode. The substrate support system for the plasma processing system of claim 12 further comprises: A controller configured to use the measured first voltage, the measured second voltage, the capacitance of the lower portion of the substrate support, and the capacitance of the upper portion of the substrate support to determine the voltage on the top surface of the substrate. An edge ring system for a plasma processing system, comprising: an edge ring, configured to confine a substrate support; an edge ring electrode, configured in the edge ring, the edge ring electrode being configured to control a voltage on a top surface of the edge ring and to receive a bias voltage customized RF waveform from a voltage supply system, wherein the edge ring electrode is configured to electrically receive a first connector for measuring a first voltage on the edge ring electrode; and An edge ring intermediate electrode is arranged in the edge ring so that a lower portion of the edge ring exists between the edge ring electrode and the edge ring intermediate electrode, and an upper portion of the edge ring exists between the edge ring intermediate electrode and the top surface of the edge ring, wherein the edge ring intermediate electrode is arranged to electrically receive a second connector for measuring a second voltage on the edge ring intermediate electrode. The edge ring system for the plasma processing system as claimed in claim 14 further comprises: A controller configured to use the measured first voltage, the measured second voltage, the capacitance of the lower portion of the edge ring, and the capacitance of the upper portion of the edge ring to determine the voltage on the top surface of the edge ring. A method for controlling voltage on a substrate, comprising: Operating a voltage supply system to supply a bias voltage customized RF waveform to a bias electrode in a substrate support; Measuring a first voltage on the bias electrode at a given time; Measuring a second voltage on an intermediate electrode at the given time, the intermediate electrode being arranged in the substrate support so that a lower portion of the substrate support is between the bias electrode and the intermediate electrode, and so that an upper portion of the substrate support is between the intermediate electrode and a top surface of the substrate support; and The measured first voltage, the measured second voltage, the capacitance of the lower portion of the substrate support, and the capacitance of the upper portion of the substrate support are used to determine a voltage on a top surface of the substrate when the substrate is present on the top surface of the substrate support at the given time. The method for controlling the voltage on the substrate as claimed in claim 16 further comprises: determining the difference between the voltage on the top surface of the substrate at the given time and a set point voltage; determining an adjustment to the bias voltage custom RF waveform that will reduce the difference between the voltage on the top surface of the substrate at the given time and the set point voltage; and operating the voltage supply system to implement the adjustment to the bias voltage custom RF waveform. A method for controlling the voltage on the substrate as claimed in claim 17, wherein the given time occurs during a negative segment of a cycle of the bias voltage customized RF waveform, and wherein the adjustment of the bias voltage customized RF waveform is implemented during a negative segment of a next cycle of the bias voltage customized RF waveform. A method for controlling voltage on the substrate as in claim 18, wherein the adjustment of the bias voltage customized RF waveform is a voltage change as a function of time during the negative segment of the next cycle of the bias voltage customized RF waveform. A method for controlling the voltage on the substrate as in claim 18, wherein the adjustment of the bias voltage customized RF waveform is a change in the duration of the negative segment of the next cycle of the bias voltage customized RF waveform. The method for controlling the voltage on the substrate as claimed in claim 16 further comprises: Operating the voltage supply system to supply a second bias voltage customized RF waveform to an edge ring electrode confined within an edge ring of the substrate support, wherein the bias voltage customized RF waveform supplied to the bias electrode within the substrate support is a first bias voltage customized RF waveform; Measuring a third voltage on the edge ring electrode at the given time; Measuring a fourth voltage on a middle electrode of an edge ring at the given time, the middle electrode of the edge ring being arranged in the edge ring so that a lower portion of the edge ring exists between the edge ring electrode and the middle electrode of the edge ring, and an upper portion of the edge ring exists between the middle electrode of the edge ring and a top surface of the edge ring; and Using the measured third voltage, the measured fourth voltage, the capacitance of the lower portion of the edge ring, and the capacitance of the upper portion of the edge ring to determine a voltage on the top surface of the edge ring at the given time. The method for controlling the voltage on the substrate as claimed in claim 21 further comprises: determining the difference between the voltage on the top surface of the edge ring at the given time and a set point voltage; determining an adjustment for the second bias voltage customized RF waveform that will reduce the difference between the voltage on the top surface of the edge ring at the given time and the set point voltage; and operating the voltage supply system to implement the adjustment for the second bias voltage customized RF waveform. A method for controlling the voltage on the substrate as claimed in claim 22, wherein the given time occurs during a negative segment of a cycle of the second bias voltage customized RF waveform, and wherein the adjustment of the second bias voltage customized RF waveform is implemented during a negative segment of a next cycle of the second bias voltage customized RF waveform. A method for controlling voltage on the substrate as in claim 23, wherein the adjustment of the second bias voltage customized RF waveform is a voltage change as a function of time during the negative segment of the next cycle of the second bias voltage customized RF waveform. A method for controlling the voltage on the substrate as in claim 23, wherein the adjustment of the second bias voltage customized RF waveform is a change in the duration of the negative segment of the next cycle of the second bias voltage customized RF waveform.

Images