Surface charge and power feedback as well as control using switch mode bias system

Abstract

To provide surface charge and power feedback as well as control using a switch mode bias system.SOLUTION: There are provided systems, methods and apparatus for regulating ion energies in a plasma chamber and avoiding excessive and damaging charge buildup on the substrate surface and within capacitive structures being built on the surface. An exemplary method includes placing a substrate in the plasma chamber, forming a plasma in the plasma chamber, controllably switching power to the substrate so as to apply a periodic voltage function (or a modified periodic voltage function) to the substrate, and modulating, over multiple cycles of the periodic voltage function, the periodic voltage function responsive to a defined distribution of energies of ions at the surface of the substrate so as to effectuate the defined distribution of ion energies on a time-averaged basis, and to maintain surface charge buildup below a threshold.SELECTED DRAWING: Figure 52

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to plasma processing, and more particularly, but not exclusively, to systems, methods, and apparatus for monitoring and controlling surface charge on a wafer during plasma processing of the wafer. [Background technology]

[0002] Description of Related Art During semiconductor processing, surface charge accumulation on a wafer can affect many aspects of the plasma process, including device damage and etch profiles as well as the dimensional integrity of patterned structures. For example, charge accumulation can lead to capacitive breakdown between capacitively coupled features in a chip stack. As another example, charge accumulation on surface features can deflect ions used in the etch process, leading to undesirable etch or deposition profiles (i.e., non-vertical sidewalls). Existing processes use offline experimental data accumulation and analysis to identify flags and other triggers that can be used to take corrective action during processing. However, such methods are not real-time and are prone to errors when real-time processing conditions differ somewhat from experimentally derived models. Therefore, there is a need for more accurate, real-time monitoring and control of surface charge accumulation. Summary of the Invention [Means for solving the problem]

[0003] (Summary of Disclosure) The following presents a simplified summary related to one or more aspects and / or embodiments disclosed herein. As such, the following summary is not intended to be an extensive overview related to all discussed aspects and / or embodiments, nor is it intended to identify key or essential elements related to all discussed aspects and / or embodiments or to delineate the scope associated with any particular aspect and / or embodiment. As such, the following summary is intended only to present certain concepts related to one or more aspects and / or embodiments related to the mechanisms disclosed herein in a simplified form, to preface the detailed description presented below.

[0004] In one aspect of the present disclosure, a so-called eV source uses a switch-mode power supply in conjunction with a current, voltage, or voltage source to generate a modified waveform (e.g., an asymmetric periodic waveform) that is provided to a substrate and results in charge buildup and discharge on a wafer substrate in a plasma processing chamber. The waveform can include periods of linearly decreasing voltage application to a chuck holding the wafer, followed by periodic voltage steps or ramps (e.g., voltage reversals with a finite slope between the top and bottom of each reversal) that remove charge from the wafer surface. While the voltage steps or ramps remove charge buildup on the wafer surface, the periods of linearly decreasing voltage provide a sustained negative voltage (e.g., a slight voltage slope) to the wafer surface, which attracts ions to the surface for processing. Because the linearly decreasing voltage is controlled, a controller can also monitor or control the slope of this decreasing voltage, which in turn determines the "ion current" I. I , i.e., provides knowledge of the current passing from the plasma, through the wafer, and into the eV source.

[0005] Knowledge of ionic current: Ionic current I I The surface charge accumulation Q i =I I × t, providing an accurate estimate of the surface charge accumulation Q iHowever, if the surface charge buildup Q exceeds a threshold, such as one known to lead to structural damage or other undesirable effects of surface charge buildup, a positive voltage reversal (or a sudden change in the direction of the voltage gradient) can be initiated to remove the surface charge buildup. In other words, the asymmetric periodic voltage waveform has a duration of linearly decreasing voltage between voltage reversals, and this duration is proportional to the surface charge buildup Q. i from becoming too large. Thus, the timing of the voltage reversal can be modified or controlled to provide specific charge removal or blocking of charge from exceeding a threshold.

[0006] At the same time, since the current and voltage are known, the controller also has knowledge and control of the power delivered, since P=I×V.

[0007] Some embodiments of the present disclosure may be characterized as a system for plasma-based processing, including a plasma processing chamber, a substrate support, and a power supply. The plasma processing chamber may be configured to contain a plasma including ions. The substrate support may be positioned within the plasma processing chamber and arranged to support a substrate. The power supply may be configured to provide an asymmetric periodic voltage function to an output configured to couple to the substrate support. The asymmetric periodic voltage function may have a positive voltage ramp, a first negative voltage ramp, and a second negative voltage ramp, with a duration t2 between the first negative voltage ramp and the next positive voltage ramp. The power supply is also configured to obtain a measurement of ion current in the plasma processing chamber based on monitoring at least one of current or voltage during the duration t2, and further to measure surface charge accumulation Q on the substrate as a function of ion current and duration t2. i The power supply may also include an ion current compensation component configured to obtain an estimate of the surface charge accumulation Q. i or surface charge accumulation Q i The switch controller may include a switch controller configured to keep the

[0008] Another embodiment of the present disclosure may also be characterized as an apparatus for plasma-based processing, comprising a means for obtaining measurements of ion current in a plasma processing chamber having a power supply, and a surface charge accumulation Q i and a controller for adjusting a duration t2 of the waveform. Specifically, the power supply can be configured to provide an asymmetric periodic voltage function to an output configured to couple to the substrate support. The asymmetric periodic voltage function can have a positive voltage ramp, a first negative voltage ramp, and a second negative voltage ramp, with a duration t2 between the first negative voltage ramp and the next positive voltage ramp. The means for obtaining a measurement of ion current in the plasma processing chamber can monitor at least one of the current or the voltage for the duration t2. Surface charge accumulation Q on a substrate held by the substrate support i is the means to obtain an estimate of the ion current I i and the duration t2. The controller adjusts the duration t2 to achieve the desired charge accumulation Q i can be achieved, or the surface charge accumulation Q i can be kept below a threshold.

[0009] Some embodiments of the present disclosure may be characterized as a method for biasing a substrate in a plasma processing chamber. The method may include biasing with a waveform including (1) periodic positive pulses and (2) a linearly decreasing voltage between each of the positive pulses. The linearly decreasing voltage may last for a duration t2 and have a rate of decrease dv / dt. The method then comprises: I can be calculated from the current measurements of the waveform during duration t2 or from the rate of decay dv / dt. The method then calculates the surface charge buildup Q i The ion current I I Calculate the surface charge accumulation Q from iThe method can then compare the surface charge accumulation Q i When meets or exceeds a first threshold, the duration t2 can be changed.

[0010] In one embodiment, the power supply can include a switch-mode power supply and an ion current compensation component. The power supply can include at least two switching components, including a first switching component coupled to the DC power supply and a second switching component coupled to a ground terminal. The two switching components can be configured to alternately couple the positive DC voltage and ground terminal of the DC power supply to the output of the power supply to provide a controllable narrow or monoenergetic distribution of ion energy (e.g., a single focus of specific ion energy) at the surface of the substrate. The at least two switching components can be in either a half-bridge or full-bridge configuration.

[0011] Some embodiments of the present disclosure may be characterized as a system for providing a voltage, and may include a plasma processing chamber, a substrate support, and a power supply. The plasma processing chamber may be configured to contain a plasma including ions. The substrate support may be positioned within the plasma processing chamber and arranged to support a substrate. The power supply may be configured to provide an asymmetric periodic voltage function to an output configured to couple to the substrate support, the asymmetric periodic voltage function having a positive voltage ramp, a first negative voltage ramp, and a second negative voltage ramp, with a duration t2 between the first negative voltage ramp and the next positive voltage ramp. The power supply may be configured to obtain a measurement of ion current in the plasma processing chamber based on monitoring at least one of current or voltage during the duration t2, and further to determine a surface charge accumulation Q on the substrate as a function of the ion current and the duration t2. i The power supply may further include an ion current compensation component configured to obtain an estimate of the duration t2 to achieve a desired surface charge accumulation Qi or surface charge accumulation Q i The device may include a switching controller configured to keep the voltage Vcc below a threshold.

[0012] Another embodiment of the present disclosure may be characterized as an apparatus for providing a voltage and may include a power supply. The power supply may be configured to provide an asymmetric periodic voltage function to an output configured to couple to a substrate support, the asymmetric periodic voltage function having a positive voltage ramp, a first negative voltage ramp, and a second negative voltage ramp, with a duration t2 between the first negative voltage ramp and the next positive voltage ramp. The power supply may include means for obtaining a measurement of ion current in the plasma processing chamber based on monitoring at least one of current or voltage during the duration t2. The power supply may measure a surface charge accumulation Q on a substrate carried by the substrate support as a function of the ion current and the duration t2. i The power supply may include means for adjusting the duration t2 to obtain an estimate of the desired surface charge accumulation Q i or surface charge accumulation Q i can be configured to keep the .DELTA..times ...

[0013] Yet another embodiment of the present disclosure may be characterized as a non-transitory tangible processor-readable storage medium encoded with processor-executable code for implementing a method for providing a voltage. The method may include biasing a substrate in a plasma processing chamber, the bias waveform comprising: (1) periodic positive pulses; and (2) a linearly decreasing voltage between each positive pulse, the voltage lasting for a duration t2 and having a decrease rate dv / dt. The method may further comprise: determining a voltage drop across the substrate relative to the ion current I. I from current measurements of the waveform during duration t2 or from the rate of decay dv / dt. The method still further includes calculating the surface charge buildup Q integrated during duration t2. i The ion current I IThe method may also include calculating the surface charge accumulation Q i The method may further include comparing the surface charge accumulation Q i may include varying the duration t2 when t meets or exceeds a first threshold. The present invention provides, for example, the following. (Item 1) 1. A system for providing a voltage, comprising: a plasma processing chamber configured to contain a plasma including ions; a substrate support positioned within the plasma processing chamber and arranged to support a substrate; a power supply configured to provide an asymmetric periodic voltage function to an output configured to be coupled to a substrate support, the asymmetric periodic voltage function having a positive voltage ramp, a first negative voltage ramp, and a second negative voltage ramp, the power supply having a duration t2 between the first negative voltage ramp and a next positive voltage ramp; Equipped with The power supply is configured to obtain a measurement of ion current in the plasma processing chamber based on monitoring at least one of current or voltage during the duration t2, and further to obtain a surface charge accumulation Q on the substrate as a function of the ion current and the duration t2. i an ion current compensation component configured to obtain an estimate of The power supply adjusts the duration t2 to achieve a desired surface charge accumulation Q i or the surface charge accumulation Q i a switching controller configured to keep the current below a threshold. (Item 2) Item 10. The system of item 1, wherein the ion current compensation component provides a controllable range of ion energy to the surface of the substrate. (Item 3) Item 3. The system of item 2, wherein the ion current compensation component provides a controllable narrow or monoenergetic distribution of ion energies to the surface of the substrate. (Item 4) Item 4. The system of item 3, wherein the ion current compensation component is further configured to maintain a fixed magnitude voltage or current at the output for the duration t2 to provide the controllable narrow or mono-energy distribution of ion energies at the surface of the substrate. (Item 5) Item 4. The system of item 3, wherein the power supply includes at least two switching components, the at least two switching components including a first switching component coupled to a DC power supply and a second switching component coupled to a ground terminal, the two switching components being configured to alternately couple a positive DC voltage of the DC power supply and the ground terminal to the output to provide the controllable narrow or mono-energy distribution of ion energy to the surface of the substrate. (Item 6) 6. The system of claim 5, wherein the switching controller is configured to provide first and second separate drive control signals, respectively, to first and second of the at least two switching components via corresponding ones of first and second separate drive control signal lines, control the timing of the drive control signals, alternately switch the positive DC voltage and ground potential at the output, and generate the asymmetric periodic voltage function, which, when applied to a dielectric or semiconductor substrate on the substrate support, produces a sustained negative voltage at a surface of the substrate for the duration t2, and the sustained negative voltage results in the controllable narrow or monoenergetic distribution of ion energies. (Item 7) 7. The system of claim 6, further comprising a waveform memory, the waveform memory programmed to contain timing information for the drive control signal, including the timing of the duration t2. (Item 8) Item 10. The system of item 1, wherein the estimate of surface charge accumulation is derived as an integral of the ionic current over the duration t2. (Item 9) The estimated surface charge accumulation is the series capacitance C times the rate of change of the voltage dv / dt. chuckItem 1. The system according to item 1, wherein (Item 10) 1. An apparatus for providing a voltage, comprising: a power supply configured to provide an asymmetric periodic voltage function to an output configured to couple to a substrate support, the asymmetric periodic voltage function having a positive voltage ramp, a first negative voltage ramp, and a second negative voltage ramp, with a duration t2 between the first negative voltage ramp and a next positive voltage ramp; the power supply includes means for obtaining a measurement of ion current within the plasma processing chamber based on monitoring at least one of current or voltage during the duration t2; The power supply measures the surface charge accumulation Q on the substrate carried by the substrate support as a function of the ion current and the duration t2. i means for obtaining an estimate of The power supply adjusts the duration t2 to achieve a desired surface charge accumulation Q i or the surface charge accumulation Q i a controller configured to keep a value below a threshold. (Item 11) Item 11. The apparatus of item 10, wherein the power supply provides a controllable range of ion energy to the surface of the substrate. (Item 12) Item 12. The apparatus of item 11, wherein the power supply provides a controllable narrow or mono-energetic distribution of ion energy to the surface of the substrate. (Item 13) Item 13. The apparatus of item 12, wherein the power supply is further configured to maintain a fixed magnitude voltage or current at the output for the duration t2 to provide the controllable narrow or mono-energy distribution of ion energies to the surface of the substrate. (Item 14) Item 13. The apparatus of item 12, wherein the power supply comprises at least two switching components, the at least two switching components comprising a first switching component coupled to a DC power supply and a second switching component coupled to a ground terminal, the two switching components being configured to alternately couple a positive DC voltage of the DC power supply and the ground terminal to the output to provide the controllable narrow or mono-energy distribution of ion energy to the surface of the substrate. (Item 15) Item 15. The apparatus of item 14, wherein the controller is configured to provide first and second separate drive control signals to first and second of the at least two switching components, respectively, via corresponding ones of first and second separate drive control signal lines, and control timing of the first and second separate drive control signals to alternately switch the positive DC voltage and ground potential at the output to generate the asymmetric periodic voltage function, which, when applied to a dielectric or semiconductor substrate on the substrate support, produces a sustained negative voltage at a surface of the substrate for duration t2, and the sustained negative voltage results in the controllable narrow or monoenergetic distribution of ion energies. (Item 16) Item 16. The apparatus of item 15, further comprising a waveform memory, the waveform memory programmed to contain timing information for the first and second distinct drive control signals comprising the timing of the duration t2. (Item 17) Item 11. The apparatus of item 10, further comprising the plasma processing chamber. (Item 18) 1. A non-transitory tangible processor-readable storage medium encoded with processor-executable code for implementing a method for providing a voltage, the method comprising: biasing a substrate in a plasma processing chamber, the bias waveform comprising: (1) periodic positive pulses; and (2) a linearly decreasing voltage during each of the positive pulses, the voltage lasting for a duration t2 and having a decrease rate dv / dt; Ion current I Ifrom current measurements of said waveform during said duration t2 or from said rate of decay dv / dt; The surface charge accumulation Q accumulated during said duration t2 i The ion current I I Calculating from The surface charge accumulation Q i comparing the first threshold value to the second threshold value; The surface charge accumulation Q i Varying the duration t2 when a non-transitory tangible processor-readable storage medium, (Item 19) Item 19. The non-transitory tangible processor-readable medium of item 18, wherein the duration t1 of each of the pulses is held constant during the variation of the duration t2, thereby maintaining a constant ion energy delivered to the substrate. (Item 20) The ion current I I The decrease rate dv / dt and the series capacitance C between the substrate and the power supply providing the bias chuck 20. The non-transitory tangible processor-readable medium of item 18, further comprising: (Item 21) During the duration t2, the surface charge accumulation Q i Item 21. The non-transitory tangible processor-readable medium of item 20, further comprising calculating:

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[0014] Various objects and advantages of the present disclosure as well as a more complete understanding will become apparent and readily appreciated by reference to the following detailed description and appended claims when considered in conjunction with the accompanying drawings.

[0015] [Figure 1] FIG. 1 illustrates a block diagram of a plasma processing system in accordance with one implementation of the present invention.

[0016] [Figure 2] FIG. 2 is a block diagram depicting an exemplary embodiment of the switched mode power system depicted in FIG.

[0017] [Figure 3] FIG. 3 is a schematic diagram of components that may be utilized to implement the switch-mode bias supply described with reference to FIG.

[0018] [Figure 4] FIG. 4 is a timing diagram depicting two drive signal waveforms.

[0019] [Figure 5] FIG. 5 is a graphical representation of a single mode of operating a switch mode bias supply that results in an ion energy distribution that is focused to a particular ion energy.

[0020] [Figure 6] FIG. 6 is a graph depicting a bimodal mode of operation in which two distinct peaks in the ion energy distribution are generated.

[0021] [Figure 7] 7A and 7B are graphs depicting actual direct ion energy measurements made in a plasma.

[0022] [Figure 8] FIG. 8 is a block diagram depicting another embodiment of the present invention.

[0023] [Figure 9A] FIG. 9A is a graph depicting an exemplary periodic voltage function modulated by a sinusoidal modulation function.

[0024] [Figure 9B] FIG. 9B is an exploded view of a portion of the periodic voltage function depicted in FIG. 9A.

[0025] [Figure 9C] FIG. 9C depicts the resulting distribution of ion energies resulting from sinusoidal modulation of the periodic voltage function based on time averaging.

[0026] [Figure 9D] FIG. 9D depicts actual direct ion energy measurements made in a plasma of the resulting time-averaged IEDF when the periodic voltage function is modulated by a sinusoidal modulation function.

[0027] [Figure 10] Figure 10A depicts a periodic voltage function modulated by a sawtooth modulation function. Figure 10B is an exploded view of a portion of the periodic voltage function depicted in Figure 10A. Figure 10C is a graph depicting the resulting distribution of ion energies, based on time averages, resulting from sinusoidal modulation of the periodic voltage function in Figures 10A and 10B.

[0028] [Figure 11] FIG. 11 is a graph showing the IEDF function in the right column and the associated modulation function in the left column.

[0029] [Figure 12] FIG. 12 is a block diagram depicting an embodiment in which an ion current compensation component compensates for ion current in a plasma chamber.

[0030] [Figure 13] FIG. 13 is a diagram depicting an exemplary ion current compensation component.

[0031] [Figure 14] FIG. 14 is a graph illustrating an example voltage at node Vout illustrated in FIG.

[0032] [Figure 15] 15A-15C are voltage waveforms that appear on the surface of the substrate or wafer in response to the compensation current.

[0033] [Figure 16] FIG. 16 is an exemplary embodiment of a current source that may be implemented to realize the current source described with reference to FIG.

[0034] [Figure 17] 17A and 17B are block diagrams depicting other embodiments of the present invention.

[0035] [Figure 18] FIG. 18 is a block diagram depicting yet another embodiment of the present invention.

[0036] [Figure 19] FIG. 19 is a block diagram depicting yet another embodiment of the present invention.

[0037] [Figure 20] FIG. 20 is a block diagram input parameters and control outputs that may be utilized in connection with the embodiments described with reference to FIGS. 1-19.

[0038] [Figure 21] FIG. 21 is a block diagram depicting yet another embodiment of the present invention.

[0039] [Figure 22] FIG. 22 is a block diagram depicting yet another embodiment of the present invention.

[0040] [Figure 23] FIG. 23 is a block diagram depicting yet another embodiment of the present invention.

[0041] [Figure 24] FIG. 24 is a block diagram depicting yet another embodiment of the present invention.

[0042] [Figure 25] FIG. 25 is a block diagram depicting yet another embodiment of the present invention.

[0043] [Figure 26] FIG. 26 is a block diagram depicting yet another embodiment of the present invention.

[0044] [Figure 27] FIG. 27 is a block diagram depicting yet another embodiment of the present invention.

[0045] [Figure 28] FIG. 28 illustrates a method according to an embodiment of the present disclosure.

[0046] [Figure 29] FIG. 29 illustrates another method according to an embodiment of the present disclosure.

[0047] [Figure 30] FIG. 30 illustrates one embodiment of a method for controlling the ion energy distribution of ions impacting the surface of a substrate.

[0048] [Figure 31] FIG. 31 illustrates a method for setting the IEDF and ion energy.

[0049] [Figure 32] FIG. 32 illustrates two modified periodic voltage function waveforms delivered to a substrate support according to one embodiment of the present disclosure.

[0050] [Figure 33] FIG. 33 illustrates an ion current waveform that may indicate instability in the plasma source or changes in plasma density.

[0051] [Figure 34] FIG. 34 illustrates the ion current II of a modified periodic voltage function waveform having a non-periodic shape.

[0052] [Figure 35] FIG. 35 illustrates a modified periodic voltage function waveform that may indicate a fault in the bias supply.

[0053] [Figure 36] FIG. 36 illustrates a modified periodic voltage function waveform that can indicate dynamic changes in system capacitance.

[0054] [Figure 37] FIG. 37 illustrates a modified periodic voltage function waveform that can indicate changes in plasma density.

[0055] [Figure 38] FIG. 38 illustrates a sampling of ion current for different process runs, where drift in ion current can indicate system drift.

[0056] [Figure 39] FIG. 39 illustrates a sampling of ion current for different process parameters.

[0057] [Figure 40] FIG. 40 illustrates two bias waveforms monitored without a plasma in the chamber.

[0058] [Figure 41] FIG. 41 illustrates two bias waveforms that can be used to validate a plasma process.

[0059] [Figure 42] FIG. 42 illustrates several plots of power supply voltage and ion energy showing the relationship between power supply voltage and ion energy.

[0060] [Figure 43] FIG. 43 illustrates one embodiment of a method for controlling the ion energy distribution of ions impacting the surface of a substrate.

[0061] [Figure 44] FIG. 44 illustrates various waveforms at different points in the system disclosed herein.

[0062] [Figure 45] FIG. 45 illustrates the effect of making a final incremental change in ion current compensation Ic to match ion current II.

[0063] [Figure 46] FIG. 46 illustrates the selection of ion energy.

[0064] [Figure 47] FIG. 47 illustrates the selection and expansion of the ion energy distribution function width.

[0065] [Figure 48] FIG. 48 illustrates one pattern of power supply voltage VPS that can be used to achieve more than one ion energy level, with each ion energy level having a narrow IEDF width.

[0066] [Figure 49] FIG. 49 illustrates another pattern of power supply voltage VPS that can be used to achieve more than one ion energy level, with each ion energy level having a narrow IEDF width.

[0067] [Figure 50]FIG. 50 illustrates one combination of power supply voltage VPS and ion current compensation IC that can be used to generate a defined IEDF. [Figure 51] (Not specified) [Figure 52] (Not specified) [Figure 53] (Not specified) [Figure 54] (Not specified) [Figure 55] (Not specified) [Figure 56] (Not specified) [Figure 57] (Not specified) [Figure 58] (Not specified)

[0068] [Figure 59] FIG. 59 is a diagram depicting aspects of an exemplary control system.

[0069] [Figure 60] FIG. 60 is a diagram depicting a side view of an exemplary bias supply.

[0070] [Figure 61] FIG. 61 includes a graph of the voltage waveform output from the bias supply, a graph of the corresponding sheath voltage, and a corresponding switch timing diagram.

[0071] [Figure 62] FIG. 62 is a graph depicting an example bias source waveform and example voltage values.

[0072] [Figure 63] Figure 63A depicts an implementation that uses two voltage sources to provide voltage to the bias source depicted in Figure 52. Figure 63B depicts another implementation that uses two voltage sources to provide voltage to the bias source depicted in Figure 52. Figure 63C depicts yet another implementation that uses two voltage sources to provide voltage to the bias source depicted in Figure 52.

[0073] [Figure 64] Figure 64A depicts an implementation that uses three voltage sources to provide voltages to the bias sources depicted in Figure 52. Figure 64B depicts another implementation that uses three voltage sources to provide voltages to the bias sources depicted in Figure 52. Figure 64C depicts yet another implementation that uses three voltage sources to provide voltages to the bias sources depicted in Figure 52.

[0074] [Figure 65] FIG. 65 is a diagram depicting a side view of an exemplary bias supply that interfaces with a control system.

[0075] [Figure 66] FIG. 66 illustrates a method for operating a plasma processing system in which surface charge accumulation on a substrate surface can be controlled.

[0076] [Figure 67] FIG. 67 illustrates another method for operating a plasma processing system in which surface charge accumulation on the substrate surface can be controlled.

[0077] [Figure 68] FIG. 68 illustrates a timing diagram for a power supply of a plasma processing system in which the duration t2 can be adjusted to control the surface charge accumulation Qi.

[0078] [Figure 69] FIG. 69 shows a block diagram depicting physical components that may be utilized to realize a device for operating or manufacturing a remote plasma source as disclosed herein, according to an example embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0079] (Detailed explanation) An exemplary embodiment of a plasma processing system is generally shown in Figure 1. As depicted, a plasma power supply 102 is coupled to a plasma processing chamber 104, and a switch-mode power supply 106 is coupled to a support 108 on which a substrate 110 rests within the chamber 104. Also shown is a controller 112 coupled to the switch-mode power supply 106.

[0080] In this exemplary embodiment, the plasma processing chamber 104 may be implemented by a chamber of substantially conventional construction (e.g., including a vacuum enclosure that is evacuated by a pump or pumps (not shown)). As one skilled in the art would also understand, plasma excitation within the chamber 104 may be by any one of a variety of sources, such as, for example, a helicon-type plasma source, including a magnetic coil and antenna for igniting and sustaining the plasma 114 within the reactor, and a gas inlet may be provided for introducing gas into the chamber 104.

[0081] As depicted, the exemplary plasma chamber 104 is arranged and configured to perform plasma-assisted etching of materials using energetic ion bombardment and other plasma processing (e.g., plasma deposition and plasma-assisted ion implantation) of a substrate 110. The plasma power supply 102 in this embodiment is configured to apply power (e.g., RF power) to the chamber 104 at one or more frequencies (e.g., 13.56 MHz) via a matching network (not shown) to ignite and sustain a plasma 114. It should be understood that the present invention is not limited to any particular type of plasma power supply 102 or source for coupling power to the chamber 104, and that various frequencies and power levels can be capacitively or inductively coupled to the plasma 114.

[0082] As depicted, a dielectric substrate 110 (e.g., a semiconductor wafer) to be processed is at least partially supported by a support 108, which may comprise a portion of a conventional wafer chuck (e.g., for semiconductor wafer processing). The support 108 has an insulating layer between it and the substrate 110, which may be configured to be capacitively coupled to the platform but may float at a different voltage than the support 108.

[0083] As discussed above, if the substrate 110 and the support 108 are conductors, a constant voltage can be applied to the support 108, and as a result of electrical conduction through the substrate 110, the voltage applied to the support 108 will also be applied to the surface of the substrate 110.

[0084] However, when the substrate 110 is dielectric, application of a constant voltage to the support 108 is not effective to apply a voltage across the surface of the substrate 110 being processed. As a result, the exemplary switch-mode power supply 106 is configured to be controlled to provide a voltage on the surface of the substrate 110 that is capable of attracting ions within the plasma 114 to collide with the substrate 110 to perform controlled etching and / or deposition and / or other plasma-assisted processes of the substrate 110.

[0085] Additionally, as discussed further herein, embodiments of the switch-mode power supply 106 are configured to operate to provide negligible interaction between the power applied by the plasma power supply 102 (to the plasma 114) and the power applied by the switch-mode power supply 106 to the substrate 110. The power applied by the switch-mode power supply 106 is controllable, for example, to allow control of ion energy without substantially affecting the density of the plasma 114.

[0086] 1 are realized with relatively inexpensive components that can be controlled by relatively simple control algorithms. Also, compared to prior art approaches, many embodiments of the switch-mode power supply 106 are much more efficient, reducing energy costs and expensive materials associated with removing excess heat energy.

[0087] One known technique for applying a voltage to a dielectric substrate utilizes a high-power linear amplifier in conjunction with a complex control scheme for applying power to the substrate support, which induces a voltage at the surface of the substrate. However, this technique has not been adopted by commercial entities because it has proven to be neither cost-effective nor sufficiently manageable. In particular, the linear amplifiers utilized are typically large, very expensive, inefficient, and difficult to control. Furthermore, linear amplifiers inherently require AC coupling (e.g., blocking capacitors) and auxiliary functions such as chucking, which are accomplished by parallel feed circuits that, together with the chucking, impair the AC spectral purity of the system relative to the source.

[0088] Another technique that has been considered is to apply radio frequency power to the substrate (e.g., by one or more linear amplifiers), but this technique has been found to have a detrimental effect on plasma density, since the radio frequency power applied to the substrate affects plasma density.

[0089] 1 may be implemented with buck, boost, and / or buck-boost power techniques. In these embodiments, the switch-mode power supply 106 may be controlled to apply variable levels of pulsed power and induce an electrical potential on the surface of the substrate 110.

[0090] In other embodiments, the switch-mode power supply 106 is implemented with other, more advanced switch-mode power and control techniques. Referring now to Figure 2, for example, the switch-mode power supply described with reference to Figure 1 is implemented with a switch-mode bias supply 206 that is utilized to apply power to the substrate 110 and to effect one or more desired energies of ions impacting the substrate 110. Also shown are ion energy control components 220, arc detection components 222, and a controller 212 that is coupled to both the switch-mode bias supply 206 and a waveform memory 224.

[0091] The illustrated arrangement of these components is logical. Thus, the components may be combined or further separated in an actual implementation, and the components may be connected in various ways without changing the basic operation of the system. In some embodiments, the controller 212, which may be realized, for example, by hardware, software, firmware, or a combination thereof, may be utilized to control both the power supply 202 and the switch-mode bias supply 206. However, in alternative embodiments, the power supply 202 and the switch-mode bias supply 206 are realized by completely separate functional units. As a further example, the controller 212, waveform memory 224, ion energy control portion 220, and switch-mode bias supply 206 may be integrated into a single component (e.g., residing within a common housing) or distributed among discrete components.

[0092] The switch-mode bias supply 206 in this embodiment is generally configured to apply a voltage to the support 208 in a controllable manner to produce a desired (or defined) distribution of ion energies impacting the surface of the substrate. More specifically, the switch-mode bias supply 206 is configured to produce a desired (or defined) distribution of ion energies by applying one or more specific waveforms to the substrate at specific power levels. Even more specifically, in response to input from the ion energy control portion 220, the switch-mode bias supply 206 produces specific ion energies by applying specific power levels, and applies the specific power levels using one or more voltage waveforms defined by waveform data in the waveform memory 224. As a result, one or more specific ion bombardment energies can be selected by the ion control portion to produce controlled etching (or other forms of plasma processing) of the substrate.

[0093] As depicted, the switch-mode power supply 206 includes switching components 226′, 226″ (e.g., high-power field-effect transistors) adapted to switch power to the support 208 of the substrate 210 in response to drive signals from corresponding drive components 228′, 228″. Additionally, the drive signals 230′, 230″ generated by the drive components 228′, 228″ are controlled by the controller 212 based on timing defined by the contents of the waveform memory 224. For example, the controller 212 in many embodiments is adapted to interpret the contents of the waveform memory and generate drive control signals 232′, 232″, which are utilized by the drive components 228′, 228″ to control the drive signals 230′, 230″ to the switching components 226′, 226″. Two switch components 226′, 226″, which may be arranged in a half-bridge (or full-bridge) configuration, are depicted for illustrative purposes, although it is of course contemplated that fewer or additional switch components may be implemented in various architectures (e.g., an H-bridge configuration).

[0094] In many modes of operation, the controller 212 (e.g., using waveform data) modulates the timing of the drive control signals 232′, 232″ to result in a desired waveform at the support 208 of the substrate 210. In addition, the switch-mode bias supply 206 is adapted to supply power to the substrate 210 based on an ion energy control signal 234, which may be a DC signal or a time-varying waveform. Thus, the present embodiment allows for control of ion distribution energy by controlling the timing signals to the switching components and controlling the power (controlled by the ion energy control component 220) applied by the switching components 226′, 226″.

[0095] Additionally, the controller 212 in this embodiment is configured to perform arc management functions in response to an arc in the plasma chamber 204 being detected by the arc detection component 222. In some embodiments, when an arc is detected, the controller 212 alters the drive control signals 232′, 232″ such that the waveform applied at the output 236 of the switch-mode bias supply 206 extinguishes the arc in the plasma 214. In other embodiments, the controller 212 extinguishes the arc by simply discontinuing application of the drive control signals 232′, 232″ such that the application of power at the output 236 of the switch-mode bias supply 206 is discontinued.

[0096] Referring now to FIG. 3, which is a schematic diagram of components that may be utilized to implement the switch-mode bias supply 206 described with reference to FIG. 2. As shown, switching components T1 and T2 in this embodiment are arranged in a half-bridge (also referred to as a totem-pole) topology (although a full-bridge configuration is also contemplated without departing from the spirit of the present disclosure). Collectively, R2, R3, C1, and C2 represent the plasma load, C10 is the effective capacitance (also referred to herein as the series capacitance or chuck capacitance), and C3 is any physical capacitor that prevents DC current from the voltage induced on the surface of the substrate or the voltage of the electrostatic chuck (not shown) from flowing through the circuit. C10 is referred to as the effective capacitance because it includes the series capacitance (also referred to as the chuck capacitance) of the substrate support and electrostatic chuck (or E-chuck), as well as other capacitances inherent in the application of bias, such as insulation and the substrate. As depicted, L1 is a stray inductance (e.g., the natural inductance of the conductor supplying power to the load). Also, in this embodiment, there are three inputs: V bus , V2, and V4 exist.

[0097] V2 and V4 represent drive signals (e.g., drive signals 230′, 230″ output by drive components 228′, 228″ described with reference to FIG. 2), and in this embodiment, V2 and V4 represent voltage outputs V out The switching components T1 and T2 can be synchronized (e.g., the length and / or mutual delay of the switch pulses) so that the shape of V can be controlled. In many implementations, the transistors used to realize the switching components T1 and T2 are not ideal switches, and therefore transistor-specific characteristics are taken into account to arrive at the desired waveform. In many operating modes, simply changing the timing of V2 and V4 can adjust V out This allows the application of a desired waveform at

[0098] For example, switches T1, T2 may be operated so that the voltage at the surface of the substrate 110, 210 is generally negative, with periodic voltage reversals that approach and / or slightly exceed a positive voltage reference. The value of the voltage at the surface of the substrate 110, 210 defines the energy of the ions and may be characterized in terms of an ion energy distribution function (IEDF). To produce a desired voltage at the surface of the substrate 110, 210, V out The waveform portion at may be generally rectangular (or have ramp sides, as shown in Figures 61-62) and have a width long enough to induce a short positive voltage at the surface of the substrate 110, 210 to attract enough electrons to the surface of the substrate 110, 210 to achieve the desired voltage and corresponding ion energy.

[0099] The periodic voltage reversals approaching and / or slightly exceeding the positive voltage reference may have a minimum time limited by the switching capabilities of switches T1 and T2. The generally negative portion of the voltage may extend as long as the voltage does not build up to a level that damages the switches. In some embodiments, the length of the negative portion of the voltage may be selected based on the sheath transit time of the ions.

[0100] V in this embodiment bus is the measured V of the waveform portion that defines the voltage at the surface of the substrate and, consequently, the ion energy. out Referring briefly to Figure 2 again, V bus may be coupled to an ion energy control portion, the ion energy control portion being V bus This may be achieved by a DC power supply adapted to apply a DC signal or a time-varying waveform to the

[0101] The switch pulse width, switch pulse shape, and / or mutual delay of the two signals V2, V4 are determined by V out (also referred to herein as a modified periodic voltage function) can be modulated to arrive at a desired waveform, V busThe voltage applied to V can affect the characteristics of the switch pulse. bus can affect the switch pulse width, switch pulse shape, and / or relative phase of signals V2, V4. Referring briefly to FIG. 4, for example, V out A timing diagram is shown depicting two drive signal waveforms (as V2 and V4) that can be applied to T1 and T2 to generate a periodic voltage function at V out To modulate the shape of the waveform part at out In this case, the timing of the two gate drive signals V2, V4 can be controlled (to achieve the minimum time of the switch pulse but reach the peak value of the voltage waveform).

[0102] For example, each switch pulse is V out Two gate drive signals V2, V4 may be applied to the switching components T1, T2 such that the time applied at V is short compared to the time T between switch pulses, but may be long enough to induce a positive voltage at the surface of the substrate 110, 210 and attract electrons to the surface of the substrate 110, 210. Furthermore, by changing the gate voltage level between the switch pulses, the voltage V between waveform portions may be varied. out It has been found that the slope of the voltage applied to the gate pulse can be controlled (e.g., to achieve a substantially continuous or constant voltage at the surface of the substrate between voltage reversals). In some modes of operation, the repetition rate of the gate pulses is about 400 kHz, although this rate can, of course, be variable from application to application. A waveform portion can be defined, for example, as the rising portion between the plateau voltage regions in Figures 9b and 10b, or the portion during t1 in Figure 14 (the waveform portion includes first, second, and third portions 1402, 1404, and 1406 in Figure 14), or the portion during t1 in Figure 61 (the waveform portion includes first, second, and third portions 6160, 6162, and 6164 in Figure 61).

[0103] In practice, although not required, a waveform may be defined that can be used to generate a desired (or defined) ion energy distribution based on modeling and refinement of the actual implementation, and the waveform may be stored (e.g., as a duration of voltage levels in the waveform memory portion described with reference to FIG. 1). Additionally, in many implementations, the waveform may be generated directly (e.g., V out (without feedback from ), thus avoiding undesirable aspects of feedback control systems (e.g., settling time).

[0104] Referring again to Figure 3, V bus can be modulated to control the energy of the ions, and the stored waveforms are used to control the gate drive signals V2, V4, and V out The switch pulse width can be minimized while achieving the desired waveform amplitude at V. Again, this is done according to the specific characteristics of the transistor, which can be modeled or implemented and established experimentally. Referring to Figure 5, for example, bus Graphs are shown depicting the voltage at the surface of the substrate 110, 210 versus time, and the corresponding ion energy distribution.

[0105] 5 depicts a single mode of operating the switch-mode bias supplies 106, 206, which results in an ion energy distribution that is focused to a particular ion energy. As depicted, to achieve a single focus of ion energy in this example, V bus is held constant, while the voltages applied to V2 and V4 are controlled (e.g., using the drive signals depicted in FIG. 3) to generate pulses at the output of the switch-mode bias supplies 106, 206 that result in the corresponding ion energy distribution shown in FIG. 5.

[0106] 5, the potential at the surface of the substrate 110, 210 is generally negative, attracting ions that bombard and etch the surface of the substrate 110, 210. Periodic short pulses (pulses Vout (by applying to V bus These pulses have a magnitude defined by the potential applied to the substrate 110, 210, and cause a short change in potential (e.g., a near-positive or weakly positive potential) at the substrate 110, 210, which attracts electrons to the surface of the substrate to achieve a generally negative potential along the surface of the substrate 110, 210. As depicted in FIG. bus A constant voltage applied to V results in a single focused ion flux at a specific ion energy. Therefore, a specific ion bombardment energy is obtained by applying a specific potential to V. bus In other modes of operation, two or more separate concentrations of ion energy may be generated (see, for example, FIG. 49).

[0107] Those skilled in the art will recognize that the power supply need not be limited to a switch mode power supply, and therefore the output of the power supply can also be controlled to achieve a certain ion energy. Thus, the output of the power supply, whether switch mode or otherwise, when considered without ion current compensation or in combination with the ion current, can be expressed as the power supply voltage V PS This power supply voltage V PS is also equal to the voltage drop ΔV in Figs.

[0108] 6, for example, a graph is shown depicting a bimodal mode of operation in which two distinct peaks in the ion energy distribution are generated. As shown, in this mode of operation, the substrate is subjected to two different levels of voltage and periodic pulses, resulting in two distinct concentrations of ion energy. As depicted, to produce the two different ion energy concentrations, V bus The voltage applied at alternates between two levels, each level defining an energy level for two ion energy concentrations.

[0109] 6 depicts the two voltages at the substrate 110, 210 as alternating after each pulse (e.g., FIG. 48), this is not necessarily required. In other modes of operation, for example, the voltages applied to V2 and V4 may be alternating between V1 and V2 such that the voltage induced at the surface of the substrate alternates from a first voltage to a second voltage (or vice versa) after two or more pulses (e.g., FIG. 49). out (eg, using the drive signals depicted in FIG. 3) relative to the voltage applied to the

[0110] Prior art attempts to achieve multiple ion energies have been made by applying a combination of two waveforms (generated by a waveform generator) to a linear amplifier and then applying the amplified combination of two or more waveforms to the substrate. However, this approach is significantly more complex than the approach described with reference to FIG. 6 and therefore requires expensive linear amplifiers and waveform generators.

[0111] Referring now to Figures 7A and 7B, V bus Graphs are shown depicting actual direct ion energy measurements made in a plasma corresponding to controllable narrow single-energy and dual-level adjustments of the DC voltage applied to V. As depicted in FIG. 7A, the ion energy distribution varies with V. bus ion energy is focused at approximately 80 eV (e.g., as depicted in FIG. 5) in response to a constant application of voltage to V. Also, in FIG. 7B, two separate focuses of ion energy are shown at V bus , located at approximately 85 eV and 115 eV in response to dual level modulation (e.g., as depicted in FIG. 6).

[0112] 8, a block diagram depicting another embodiment of the present invention is shown. As depicted, a switch-mode power supply 806 is coupled to a substrate support 808 via a controller 812, an ion energy control component 820, and an arc detection component 822. The controller 812, the switch-mode power supply 806, and the ion energy control component 820 collectively operate to provide power to the substrate support 808 to produce a desired (or defined) ion energy distribution at the surface of the substrate 810 on a time-averaged basis.

[0113] For example, referring briefly to FIG. 9A, a periodic voltage function with a frequency of approximately 400 kHz is shown modulated by a sinusoidal modulation function of approximately 5 kHz over multiple cycles of the periodic voltage function. FIG. 9B is an exploded view of the portion of the periodic voltage function circled in FIG. 9A, and FIG. 9C depicts the resulting distribution of ion energies, based on time averages, resulting from the sinusoidal modulation of the periodic voltage function. Also, FIG. 9D depicts actual direct ion energy measurements made in a plasma of the time-averaged IEDF that results when the periodic voltage function is modulated by a sinusoidal modulation function. As discussed further herein, achieving a desired (or defined) ion energy distribution based on time averages can be achieved by simply varying the modulation function applied to the periodic voltage.

[0114] As another example, with reference to Figures 10A and 10B, a 400 kHz periodic voltage function is modulated by an approximately 5 kHz sawtooth modulation function to achieve the time-averaged distribution of ion energies depicted in Figure 10C. As depicted, the periodic voltage function utilized in connection with Figure 10 is the same as that in Figure 9, except that the periodic voltage function in Figure 10 is modulated by a sawtooth function instead of a sinusoidal function.

[0115] It should be appreciated that the ion energy distribution functions depicted in Figures 9C and 10C do not represent the instantaneous distribution of ion energies at the surface of the substrate 810, but instead represent a time average of ion energies. With reference to Figure 9C, for example, at a particular instant in time, the distribution of ion energies will be a subset of the depicted distribution of ion energies that exists over the course of one cycle of the modulation function.

[0116] It should also be recognized that the modulation function need not be a fixed function or fixed frequency. For example, in some cases it may be desirable to modulate the periodic voltage function by one or more cycles of a particular modulation function to result in a particular time-averaged ion energy distribution, and then modulate the periodic voltage function by one or more cycles of another modulation function to result in a different time-averaged ion energy distribution. Such changes to the modulation function (modulating the periodic voltage function) can be beneficial in many cases. For example, if a particular ion energy distribution is needed to etch a particular geometric structure or to etch through a particular material, a first modulation function can be used, and then a different modulation function can be subsequently used to result in a different etch geometry or to etch through a different material.

[0117] Similarly, periodic voltage functions (e.g., the 400 kHz component in Figures 9A, 9B, 10A, and 10B, and the V out ) need not be strictly fixed (e.g., the shape and frequency of the periodic voltage function can vary). In some embodiments, the frequency is established by the transit time of the ions through the sheath, such that the acceleration of the ions is affected by the voltage applied to the substrate 810 in a desired manner.

[0118] 8, controller 812 provides drive control signals 832′, 832″ to switch-mode source 806 such that switch-mode source 806 generates a periodic voltage function. Switch-mode source 806 may be realized by the components depicted in FIG. 3 (e.g., to generate the periodic voltage function depicted in FIG. 4), although it is of course envisioned that other switching architectures may be utilized.

[0119] In general, ion energy control component 820 functions to apply a modulation function to a periodic voltage function (generated by controller 812 in conjunction with switch-mode power supply 806). As shown in Figure 8, ion energy control component 820 includes a modulation controller 840 in communication with a custom IEDF portion 850, an IEDF function memory 848, a user interface 846, and a power component 844. It should be recognized that the depiction of these components is intended to convey functional components that may, in fact, be provided by common or separate components.

[0120] Modulation controller 840 in this embodiment generally controls power component 844 (and thus its output 834) based on data defining a modulation function, which generates modulation function 834 (based on control signal 842 from modulation controller 840) that is applied to the periodic voltage function generated by switch-mode supply 806. User interface 846 in this embodiment is configured to allow a user to select a pre-defined IEDF function stored in IEDF function memory 848 or, in association with custom IEDF component 850, define a custom IEDF.

[0121] In many implementations, the power component 844 applies a modulation function (e.g., a variable DC voltage) to a switch-mode power supply (e.g., the V bus) In these implementations, modulation controller 840 controls the voltage level output by power component 844 such that power component 844 applies a voltage that matches the modulation function.

[0122] In some implementations, the IEDF function memory 848 includes multiple data sets corresponding to each of multiple IEDF distribution functions, and the user interface 846 allows a user to select a desired (or defined) IEDF function. For example, referring to FIG. 11 , the right column shows exemplary IEDF functions that may be available for user selection. The left column also depicts an associated modulation function that the modulation controller 840, in conjunction with the power component 844, would apply to the periodic voltage function to result in the corresponding IEDF function. It should be appreciated that the IEDF function depicted in FIG. 11 is merely exemplary, and other IEDF functions may also be available for selection.

[0123] The custom IEDF component 850 generally functions to allow a user to define a desired (or defined) ion energy distribution function via the user interface 846. For example, in some implementations, the custom IEDF component 850 allows a user to establish values ​​for particular parameters that define the distribution of ion energies.

[0124] For example, the custom IEDF component 850 may allow an IEDF function to be defined in terms of relative levels of flux (e.g., in terms of flux percentages) at a high level (IF-high), a mid-level (IF-mid), and a low level (IF-low), in conjunction with a function that defines the IEDF between these energy levels. In many cases, the IF-high, IF-low, and IEDF functions between these levels alone are sufficient to define the IEDF function. As a specific example, a user may request 1,200 eV at the 20% contribution level (contribution to the overall IEDF) and 700 eV at the 30% contribution level, with a sinusoidal IEDF between these two levels.

[0125] It is also envisioned that custom IEDF portion 850 may enable a user to import a table with a list of one or more (e.g., multiple) energy levels and each energy level's corresponding percentage contribution to the IEDF. It is also envisioned that in a further alternative embodiment, custom IEDF component 850, in conjunction with user interface 846, enables a user to graphically generate a desired (or defined) IEDF by presenting the user with a graphical tool that enables the user to draw the desired (or defined) IEDF.

[0126] In addition, it is also envisioned that the IEDF function memory 848 and the custom IEDF component 850 may interoperate to allow a user to select a predetermined IEDF function and then modify the predetermined IEDF function to produce a custom IEDF function that is derived from the predetermined IEDF function.

[0127] Once the IEDF function is defined, modulation controller 840 converts data defining the desired (or defined) IEDF function into control signals 842 that control power components 844 such that power components 844 provide a modulation function corresponding to the desired (or defined) IEDF. For example, control signals 842 control power components 844 such that power components 844 output a voltage defined by the modulation function.

[0128] 12, a block diagram of an embodiment is depicted in which an ion current compensation component 1260 compensates for ion current within the plasma chamber 1204. Applicants have discovered that at higher energy levels, the higher level of ion current within the chamber affects the voltage at the surface of the substrate, and as a result, the ion energy distribution is also affected. For example, referring briefly to Figures 15A-15C, the voltage waveform as it appears at the surface of the substrate 1210 or wafer and its relationship to the IEDF are shown.

[0129] More specifically, FIG. 15A shows the ion current I I 15B depicts the periodic voltage function at the surface of the substrate 1210 when the ion current I I 15C depicts the voltage waveform at the surface of the substrate 1210 when the ion current is greater than the compensation current Ic, and FIG. 15D depicts the voltage waveform at the surface of the substrate when the ion current is less than the compensation current Ic.

[0130] As depicted in FIG. 15A, I I When I = Ic, the spread of ion energy 1470 is depicted in FIG. 15B. I >Ic, or the uniform spread of ion energies 1472 depicted in FIG. 15C, I ICompared with the uniform spread 1474 of the ion energy at Ic, it is relatively narrow. Therefore, the ion current compensation component 1260 enables a narrow spread of ion energy when the ion current is high (e.g., by compensating for the influence of the ion current), and also enables control of the width of the uniform ion energy spreads 1572, 1574 (e.g., when it is desirable to have a spread of ion energy).

[0131] As depicted in FIG. 15B, when there is no ion current compensation (I I >Ic), the voltage at the surface of the substrate between the positive portions of the periodic voltage function becomes less negative in a ramp-like fashion, which produces a wider spread 1572 of ion energy. Similarly, when ion current compensation is utilized to increase the level of the compensation current beyond the level of the ion current (I I <Ic) as depicted in FIG. 15C, the voltage at the surface of the substrate becomes more negative in a ramp-like fashion between the positive portions of the periodic voltage function, and a wider spread 1574 of uniform ion energy is produced.

[0132] Referring back to FIG. 12, the ion current compensation component 1260 can be realized as a separate attachment that can optionally be added to the switch mode power supply 1206 and the controller 1212. In other embodiments (e.g., as depicted in FIG. 13), the ion current compensation component 1260 can share a common housing 1366 with other components described herein (e.g., switch mode power supplies 106, 206, 806, 1206 and ion energy control 220, 820 components). In this embodiment, the periodic voltage function provided to the plasma chamber 1204 can be referred to as a modified periodic voltage function since it comprises the periodic voltage function modified by the ion current compensation from the ion current compensation component 1260. The controller 1212 can sample the voltage at different times at an electrical node where the outputs of the switch mode power supply 1206 and the ion current compensation 1260 combine.

[0133] 13, an exemplary ion current compensation component 1360 is shown including a current source 1364 coupled to an output 1336 of the switch mode supply, and a current controller 1362 coupled to both the current source 1364 and the output 1336. Also depicted in FIG. 13 is a plasma chamber 1304, within which are capacitive elements C1, C2 and a current controller 1362 for controlling the ion current I. I As depicted, C1 represents the intrinsic capacitance (also referred to herein as effective capacitance) of components associated with the chamber 1304, which may include, but are not limited to, insulation, the substrate, the substrate support, and the electrostatic chuck, and C2 represents the sheath capacitance and stray capacitance. In this embodiment, the plasma provided to the plasma chamber 1304, V out The periodic voltage function measurable at π / (V) may be referred to as a modified periodic voltage function because it comprises a periodic voltage function modified by the ion current compensation Ic.

[0134] The sheath (also referred to herein as the plasma sheath) is a layer within the plasma near the substrate surface and possibly the walls of the plasma processing chamber with a high density of positive ions and therefore an overall excess of positive charge. Surfaces that the sheath contacts typically have a preponderance of negative charges. The sheath arises due to the faster velocity of electrons than the positive ions, thus causing a majority of the electrons to reach the substrate surface or walls, thus stealing electrons from the sheath. The sheath thickness λ sheath is a function of plasma properties such as plasma density and plasma temperature.

[0135] Note that C1 in this embodiment is the inherent (also referred to herein as effective) capacitance of components associated with chamber 1304, and is not an accessible capacitance that is added to gain process control. For example, some prior art approaches utilizing linear amplifiers couple bias power to the substrate with a blocking capacitor and then use the monitored voltage of the blocking capacitor as feedback to control the linear amplifier. While a capacitor may couple the switch-mode power supply to the substrate support in many of the embodiments disclosed herein, doing so is unnecessary because feedback control using a blocking capacitor is not required in some embodiments of the present invention.

[0136] With reference to FIG. 13, the V depicted in FIG. out Reference is also made to FIG. 14, which is a graph depicting an example voltage (e.g., a modified periodic voltage function) at V. In operation, the current controller 1362 controls the out The voltage at is monitored and the ionic current is calculated over an interval t (depicted in FIG. 14) as follows:

number

[0137] Ion current I I and the intrinsic capacitance C1 (also called effective capacitance) can be either or both time-varying waveforms. Since C1 is essentially a constant for a given tool and can be measured, V out Only the compensation current needs to be monitored to allow for continuous control of the compensation current. As described above, to obtain a more monoenergetic distribution of ion energies (e.g., as depicted in FIG. 15A), the current controller adjusts Ic to be substantially equal to I I15B and 15C , where ion energy spread is controlled such that ion energy is equal to (or alternatively related according to Equation 2) . In this way, a narrow spread of ion energies can be maintained even when the ion current reaches a level that affects the voltage at the surface of the substrate. Additionally, if desired, the spread of ion energies can be controlled, as depicted in FIGS. 15B and 15C , so that additional ion energy is realized at the surface of the substrate.

[0138] Also depicted in Figure 13 is a feedback line 1370 that may be utilized in connection with controlling the ion energy distribution. For example, the value of ΔV depicted in Figure 14 (also referred to herein as the voltage step or third portion 1406) indicates the instantaneous ion energy and may be used in many embodiments as part of a feedback control loop. In one embodiment, the voltage step ΔV is related to the ion energy according to Equation 4. In other embodiments, the peak-to-peak voltage V PP can be related to the instantaneous ion energy. Alternatively, the peak-to-peak voltage V multiplied by time t PP and the product dV / dt of the slope of the fourth portion 1408 can be correlated to the instantaneous ion energy (e.g., V PP -dV0 / dt·t).

[0139] 16, there is shown an exemplary embodiment of a current source 1664 that may be implemented to realize the current source 1364 described with reference to FIG. 13. In this embodiment, a controllable negative DC voltage source, in conjunction with series inductor L2, functions as the current source, although those skilled in the art will understand in light of this specification that the current source may be realized with other components and / or configurations.

[0140] 43 illustrates one embodiment of a method for controlling the ion energy distribution of ions impacting a surface of a substrate. The method 4300 begins with applying a modified periodic voltage function 4302 (see modified periodic voltage function 4402 in FIG. 44) to a substrate support supporting a substrate in a plasma processing chamber. The modified periodic voltage function is applied to an ion current compensation I C (Figure 44 I C 4404) and power supply voltage V PS (see power supply voltage 4406 in FIG. 44). An exemplary component for generating the power supply voltage is the switched mode power supply 106 in FIG. 1. The power supply voltage V PS To help explain this, it is illustrated herein as if it were measured without coupling to the ion current and ion current compensation. The modified periodic voltage function is then calculated using the ion current compensation I C 4304. At least two samples of the voltage of the modified periodic voltage function are sampled at first and second values ​​of ion current compensation I C The sampling 4304 is performed for each value of the ion current I I and sheath capacitance C sheath Such determination is performed to enable calculation 4306 (or determination) of an ion current compensation I 4306 that, when applied to the substrate support (or as applied to the substrate support), would produce a narrow (e.g., minimum) ion energy distribution function (IEDF) width. C Calculation 4306 may also optionally include determining a voltage step ΔV (also known as the third portion of the modified periodic voltage function 1406) based on sampling 4304 of the waveform of the modified periodic voltage function. The voltage step ΔV may be related to the ion energy of the ions arriving at the surface of the substrate. Initially, the ion current I I The voltage step ΔV can be neglected when finding {overscore (V)}. Details of sampling 4304 and calculation 4306 will be provided in the discussion of FIG. 30 below.

[0141] Once the ion current I I and sheath capacitance C sheath Once this is known, method 4300 may proceed to method 3100 of FIG. 31, which involves setting and monitoring the ion energy and the shape (e.g., width) of the IEDF. For example, FIG. 46 illustrates how a change in power supply voltage can result in a change in ion energy. In particular, the magnitude of the power supply voltage shown is reduced, resulting in a decrease in the magnitude of the ion energy. Additionally, FIG. 47 illustrates how, given a narrow IEDF 4714, ion current compensation I C Alternatively, or in parallel, method 4300 may adjust the ion current I I , sheath capacity C sheath , and other aspects of the waveform of the modified periodic voltage function, various measurements can be performed as described with reference to FIGS. 32-41.

[0142] In addition to setting the ion energy and / or IEDF width, the method 4300 may adjust the modified periodic voltage function 4308 to maintain the ion energy and IEDF width. In particular, the ion current compensation I provided by the ion current compensation component C and power supply voltage adjustment may be performed 4308. In some embodiments, the power supply voltage is adjusted to the power supply bus voltage V bus (For example, the bus voltage V in Figure 3 bus ) can be controlled by the ion current compensation I C controls the IEDF width and the power supply voltage controls the ion energy.

[0143] After these adjustments 4308, the modified periodic voltage function can be sampled again 4304, and the ionic current I I , sheath capacity C sheath , and the calculation of the voltage step ΔV can again be performed 4306. The ion current I Ior if the voltage step ΔV is other than a defined value (or alternatively a desired value), the ion current compensation I C And / or the power supply voltage can be adjusted 4308. A loop of sampling 4304, calculation 4306, and adjustment 4308 can occur to maintain the ion energy eV and / or IEDF width.

[0144] FIG. 30 illustrates another embodiment of a method for controlling the ion energy distribution of ions impacting the surface of a substrate. In some embodiments, as discussed above, it may be desirable to achieve a narrow IEDF width (e.g., a minimum IEDF width or alternatively, about 6% full width at half maximum). Accordingly, method 3000 can provide a modified periodic voltage function to the chamber and substrate support such that a constant substrate voltage (or sustained or substantially constant substrate voltage), and thus a sheath voltage, is present at the surface of the substrate. This, in turn, accelerates ions across the sheath at a substantially constant voltage, thus allowing the ions to impact the substrate with substantially the same ion energy, which in turn provides a narrow IEDF width. For example, in FIG. 45, ion current compensation I C By adjusting the substrate voltage V between pulses, sub It can be seen that this allows the IEDF to be narrowed by having a constant or substantially constant (or sustained) voltage.

[0145] Such a modified periodic voltage function does not assume any stray capacitance and has an ionic current compensation I C is the ion current I I (See the last five cycles of the periodic voltage function (V0) in Figure 45.) stray In the alternative, where is considered, the ion current compensation I C is the ionic current I according to Equation 2 I Related to.

number

[0146] where C1 is the effective capacitance (e.g., the intrinsic capacitance described with reference to Figures 3 and 13). The effective capacitance C1 may vary over time or may be constant. For purposes of this disclosure, a narrow IEDF width is defined as I I =I C or alternatively, when Equation 2 is satisfied. Figures 45-50 illustrate Nomenclature I I =I C It should be understood that these equations are merely simplifications of Equation 2, and thus Equation 2 can be substituted for the equations used in Figures 45-50. stray is the cumulative capacity of the plasma chamber as seen by the power supply. There are eight cycles illustrated in FIG.

[0147] The method 3000 may begin with application of a modified periodic voltage function (e.g., the modified periodic voltage function depicted in FIG. 14 or the modified periodic voltage function 4402 of FIG. 44) to a substrate support 3002 (e.g., the substrate support 108 of FIG. 1). The voltage of the modified periodic voltage function may be sampled two or more times 3004, and from this sampling, a slope dV0 / dt for at least a portion of a cycle of the modified periodic voltage function may be calculated 3006 (e.g., the slope of the portion during the pulse or the fourth portion 1408). At some point before the decision 3010, a previously determined value of the effective capacitance C1 (e.g., the intrinsic capacitance C1 of FIG. 13 and the intrinsic capacitance C10 of FIG. 3) may be accessed (e.g., from memory or from user input) 3008. The slope dV0 / dt, the effective capacitance C1, and the ion current compensation I C Based on this, the function f (Equation 3) is calculated as follows to calculate the ion current compensation I C can be evaluated for each.

number

[0148] If the function f is true, then the ion current compensation I C is the ion current II or alternatively, Equation 2 is made true and a narrow IEDF width is achieved 3010 (see, for example, FIG. 45). If the function f is not true, the ion current compensation I is C can be further adjusted 3012. From another perspective, the ion current I I (or alternatively, satisfy the relationship in Equation 2) C can be adjusted, at which point there will be a narrow IEDF width. Such an adjustment to the ion current compensation Ic and the resulting narrowing of the IEDF can be seen in Figure 45. The ion current I I and the corresponding ion current compensation Ic can be stored (e.g., in a memory) in a storage operation 3014. C may vary over time, as may the effective capacity C1.

[0149] When equation 3 is satisfied, (I C =I I (either because Equation 2 is true or because I Therefore, the method 3000 can measure the ion current I in real time without affecting the plasma. I This leads to several novel measurements such as those that will be described with reference to Figures 32-41 (e.g., remote monitoring of plasma density and remote fault detection of the plasma source).

[0150] Compensation current I C While adjusting 3012, the ion energy will likely be broader than the delta function and will resemble either of Figures 15B, 15C, or 44. However, once the compensation current I satisfies Equation 2, C When I is found, the IEDF will appear to have a narrow IEDF width (e.g., minimum IEDF width), as shown in the right portion of FIG. 15A or FIG. 45. This is because I C =I I(or alternatively, when Equation 2 is true), the voltage between pulses of the modified periodic voltage function will result in a substantially constant sheath or substrate voltage, and therefore ion energy. In Figure 46, the substrate voltage 4608 includes pulses (or voltage reversals) between constant voltage portions (or substantially constant voltage portions or sustained voltage portions). Because these pulses have very short durations, their effect on ion energy and IEDF is negligible, and therefore the substrate voltage 4608 is referred to as substantially constant (or sustained).

[0151] The following provides further details about each of the method steps illustrated in FIG. 30. In one embodiment, the modified periodic voltage function may have a waveform such as that illustrated in FIG. 14 and may include a first portion (e.g., first portion 1402), a second portion (e.g., 1404), a third portion (e.g., third portion 1406), and a fourth portion (e.g., fourth portion 1408), where the third portion may have a voltage step ΔV and the fourth portion may have a slope dV / dt. The slope dV / dt may be positive, negative, or zero. The modified periodic voltage function 1400 may also be represented as having pulses, comprising first portion 1402, second portion 1404, and third portion 1406, as well as a portion between the pulses (fourth portion 1408). In practice, the transitions between the portions are more likely to each have a sloped voltage rise and fall, as shown, for example, in FIG.

[0152] The modified periodic voltage function is shown in Figure 3 as V outand can appear in FIG. 44 as modified periodic voltage function 4402. Modified periodic voltage function 4402 is produced by combining power supply voltage 4406 (known as the periodic voltage function) with ion current compensation 4404. Power supply voltage 4406 is largely responsible for generating and shaping the pulses of modified periodic voltage function 4402, and ion current compensation 4404 is largely responsible for generating and shaping the inter-pulse portion, which is often a linearly decreasing voltage with a slope. Increasing ion current compensation Ic causes a decrease in the magnitude of the slope of the inter-pulse portion, as seen in FIG. 45. Decreasing the magnitude of power supply voltage 4606 causes a decrease in the magnitude of the pulses and peak-to-peak voltage amplitude of modified periodic voltage function 4602, as seen in FIG. 46.

[0153] In the case where the power supply is a switched-mode power supply, the switching diagram 4410 of the first switch T1 and the second switch T2 can be applied. For example, the first switch T1 can be implemented as switch T1 in FIG. 3, and the second switch T2 can be implemented as switch T2 in FIG. 3. The two switches are shown as closed at the beginning and end of each pulse provided by the switched-mode power supply. When the first switch T1 is on or closed, the power supply has a negative bus voltage, so the power supply voltage is pulled to its maximum magnitude, which is a negative value in FIG. 44. The second switch T2 is turned off during this period so that the power supply voltage 4406 is isolated from ground. The first switch T1 is only turned on or closed momentarily and then turned off, and the ion current compensation component maintains the output V for a second duration t2 between pulses (i.e., the linearly decreasing portion between pulses). outWhen the second switch T2 is turned on, the power supply voltage 4406 approaches and slightly exceeds ground. Both the first duration t1 of each pulse as well as the second duration of the linearly decreasing voltage between pulses can be adjusted to different requirements. For example, the second duration t2 can be adjusted to accommodate the surface charge accumulation Q i can be controlled to prevent it from exceeding a threshold or moving outside a desired range.

[0154] Apply the modified periodic voltage function to the substrate support 3002 and V out 3004. The uncorrected periodic voltage function (or power supply voltage 4406 in FIG. 44) can be provided from a power supply such as switch mode power supply 1206 in FIG. 12. The ion current compensation 4404 in FIG. 44 can be provided from a voltage or current source such as ion current compensation component 1260 in FIG. 12 or 1360 in FIG. 13.

[0155] A portion or the entirety of the modified periodic voltage function may be sampled 3004. For example, the fourth portion (e.g., fourth portion 1408) may be sampled. The sampling 3004 may be performed between the power supply and the substrate support. For example, in FIG. 1, the sampling 3004 may be performed between the switch mode power supply 106 and the support 108. In FIG. 3, the sampling 3004 may be performed between the inductor L1 and the intrinsic capacitance C10. In one embodiment, the sampling 3004 may be performed between the V between the capacitance C3 and the intrinsic capacitance C10. out3. Because the intrinsic capacitance C10 and the elements representing the plasma (R2, R3, C1, and C2) are not accessible for real-time measurement, sampling 3004 is typically performed to the left of the intrinsic capacitance C10 in FIG. 3. The intrinsic capacitance C10 is typically not measured during processing, but is typically a known constant and therefore can be set during manufacturing. At the same time, it is possible that the intrinsic capacitance C10 may vary over time.

[0156] In some embodiments, only two samples of the modified periodic voltage function are required, while in other embodiments, hundreds, thousands, or tens of thousands of samples can be obtained per cycle of the modified periodic voltage function. For example, sampling rates can be greater than 400 kHz. These sampling rates enable more accurate and detailed monitoring of the modified periodic voltage function and its shape. Similarly, more detailed monitoring of the periodic voltage function enables more accurate comparison of waveforms between cycles, different process conditions, different processes, different chambers, different sources, etc. For example, these sampling rates can distinguish the first, second, third, and fourth portions 1402, 1404, 1406, 1408 of the periodic voltage function illustrated in FIG. 14 , which may not be possible with conventional sampling rates. In some embodiments, higher sampling rates enable resolution of the voltage step ΔV and slope dV0 / dt, which is not possible with conventional techniques. In some embodiments, portions of the modified periodic voltage function can be sampled while other portions are not sampled.

[0157] The calculation 3006 of the slope dV0 / dt is performed using a number of V out For example, a linear fit can be used to fit a line to V out A fit to the values ​​can be performed, and the slope of the line is the slope dV o In another example, V at the beginning and end of time t (e.g., fourth portion 1408) in FIG. outThe value can be resolved as dV o A line can be fitted between these two points, with the slope of the line given as dV / dt. o These are just two of the many ways in which / dt can be calculated.

[0158] The determination 3010 may be part of an iterative loop used to adjust the IEDF to a narrow width (e.g., a minimum width or alternatively 6% full width at half maximum). Equation 3 shows that the ion current compensation Ic is proportional to the ion current I I (or alternatively, according to Equation 2, I I ) which only happens when there is a constant substrate voltage 4608 (V sub ) can be seen in Figure 46. Therefore, the ion current I I Alternatively, any ion current compensation, Ic, can be used in Equation 3.

[0159] Alternatively, two values ​​along the fourth portion 1408 (also referred to as the portion between voltage reversals) can be sampled over the first and second cycles, and a first and second slope can be determined for each cycle, respectively. From these two slopes, the ion current compensation I can be determined, which is expected to correspond to a narrow IEDF width by applying Equation 3 to the third, yet-to-be-measured slope. I can be estimated. These allow the narrow IEDF width to be determined and the corresponding ion current compensation Ic and / or the corresponding ion current I I are just two of the many ways in which this can be found.

[0160] The adjustment 3012 to the ion current compensation, Ic, can involve either an increase or decrease of the ion current compensation, Ic, with no limit on the step size per adjustment. In some embodiments, the sign of the function f in Equation 3 can be used to determine whether to increase or decrease the ion current compensation. If the sign is negative, the ion current compensation, Ic, can be decreased, while a positive sign can indicate a need to increase the ion current compensation, Ic.

[0161] Once the ion current I I Once the ion current compensation Ic is identified as being equal to (or alternatively related to according to Equation 2), the method 3000 can proceed to further setpoint operations (see FIG. 31) or remote chamber and source monitoring operations (see FIGS. 32-41). Further setpoint operations can include setting the ion energy (see also FIG. 46) and the ion energy distribution or IEDF width (see also FIG. 47). Source and chamber monitoring can include monitoring plasma density, source anomalies, plasma arcing, and so forth.

[0162] Additionally, method 3000 can optionally return to sampling 3004 to continuously (or alternatively periodically) update the ion current compensation Ic. For example, sampling 3004, calculation 3006, determination 3010, and adjustment 3012 can be performed periodically given the current ion current compensation Ic to ensure that Equation 3 continues to be satisfied. At the same time, if the ion current compensation Ic is updated to satisfy Equation 3, the ion current Ic I may also be updated and the updated value may be stored 3014.

[0163] The method 3000 calculates the ion current I I Although the ion current compensation Ic can be found and set to be equal to or alternatively satisfy Equation 2, the value of the ion current compensation Ic required to achieve a narrow IEDF width depends on the ion current I Ccan be determined without (or alternatively before) setting Ic1 to that value. For example, applying a first ion current compensation Ic1 over a first cycle and determining a first slope dV of the voltage between voltage reversals 01 / dt and applying a second ion current compensation Ic2 over the second cycle and determining a second slope of the voltage between voltage reversals dV 02 / dt, Equation 3 is expected to be true, and a third slope dV associated with the third ion current compensation Ic3 03 The third ion current compensation Ic3 can be one that, when applied, would result in a narrow IEDF width. Thus, only a single adjustment of the ion current compensation is required to satisfy Equation 3 and thus the ion current I I The ion current compensation Ic can then be determined, which corresponds to the ion current I C 31 and / or 32-41 without even setting t to the value required to achieve a narrow IEDF width. Such an embodiment may be implemented to increase the adjustment speed.

[0164] Figure 31 illustrates a method for setting the IEDF width and ion energy. The method originates from method 3000 illustrated in Figure 30 and can take either the left path 3100 (also referred to as the IEDF branch) or the right path 3101 (also referred to as the ion energy branch), which involves setting the IEDF width and ion energy, respectively. The ion energy eV is proportional to the voltage step ΔV or the third portion 1406 of the modified periodic voltage function 1400 of Figure 14. The relationship between the ion energy eV and the voltage step ΔV can be written as Equation 4:

number

[0165] where C1 is the effective capacitance (e.g., the chuck capacitance, the specific capacitance C10 in FIG. 3, or the specific capacitance C1 in FIG. 13), and C2 is the sheath capacitance (e.g., the sheath capacitance C4 in FIG. 3, or the sheath capacitance C2 in FIG. 13). The sheath capacitance C2 may include stray capacitance and is the capacitance that is proportional to the ion current I I The voltage step ΔV can be measured as the change in voltage between the second portion 1404 and the fourth portion 1408 of the modified periodic voltage function 1400. The voltage step ΔV (power supply voltage or bus voltage V in FIG. 3) bus By controlling and monitoring the ion energy eV, which is a function of the bus voltage, eV, the ion energy can be controlled and known.

[0166] At the same time, the IEDF width can be estimated according to Equation 5.

number

[0167] In the formula, I is C series I I or I is C is C effective I C The second duration t2 is the time between pulses, V PP is the peak-to-peak voltage and ΔV is the voltage step.

[0168] Additionally, the sheath capacitance C2 can be used in various calculations and monitoring operations, such as the device-sheath distance λ sheath can be estimated as follows:

number

[0169] where ε is the vacuum dielectric constant and A is the area of ​​the substrate (or alternatively the surface area of ​​the substrate support). In some high voltage applications, Equation 6 is written as Equation 7:

number

[0170] In addition, the electric field in the sheath is determined by the sheath capacitance C2 and the sheath distance λ sheath , and can be estimated as a function of the ion energy eV. The sheath capacitance C2 can also be estimated as a function of the ion current I I Along with the saturation current I sat Compensating current I for a plasma in which C From Equation 8, the plasma density n is linearly related to e It can also be used to determine

number

[0171] Sheath capacitance C2 and saturation current I sat Using the plasma density n, the effective mass of ions at the substrate surface can be calculated. e , the electric field in the sheath, the ion energy eV, the effective mass of the ion, and the DC potential of the substrate V DC are fundamental plasma parameters that are typically monitored in the art only through indirect means. The present disclosure allows for direct measurement of these parameters, thus enabling more accurate monitoring of plasma properties in real time.

[0172] As seen in Equation 4, the sheath capacitance C2 can also be used to monitor and control the ion energy eV, as illustrated in the ion energy branch 3101 of FIG. 31. The ion energy branch 3101 begins by receiving a user selection of ion energy 3102. The ion energy branch 3101 can then set 3104 an initial power supply voltage for a switch mode power supply that provides a periodic voltage function. At some point prior to a periodic voltage operation 3108, the ion current can also be accessed (e.g., accessed from memory) 3106. The periodic voltage can be sampled 3108, and a measurement of a third portion of the modified periodic voltage function can be measured 3110. The ion energy I I can be calculated 3112 from the voltage step ΔV of the modified periodic voltage function (also referred to as the third portion (e.g., third portion 1406)). The ion energy branch 3101 can then determine 3114 whether the ion energy is equal to the defined ion energy; if so, the ion energy is at the desired set point and the ion energy branch 3101 can end. If the ion energy is not equal to the defined ion energy, the ion energy branch 3101 can adjust 3116 the power supply voltage and again sample 3108 the periodic voltage. The ion energy branch 3101 can then cycle through sampling 3108, measuring 3110, calculating 3112, determining 3114, and setting 3116 until the ion energy is equal to the defined ion energy.

[0173] A method for monitoring and controlling the IEDF width is illustrated in IEDF branch 3100 of FIG. 31. IEDF branch 3100 includes receiving 3150 a user selection of an IEDF width and sampling 3152 a current IEDF width. A decision 3154 then determines whether the defined IEDF width is equal to the current IEDF width; if decision 3152 is satisfied, the IEDF width is as desired (or defined), and IEDF branch 3100 can end. However, if the current IEDF width is not equal to the defined IEDF width, the ion current compensation Ic can be adjusted 3156. This decision 3154 and adjustment 3156 can continue in a cyclical manner until the current IEDF width is equal to the defined IEDF width.

[0174] In some embodiments, the IEDF branch 3100 can also be implemented to ensure a desired IEDF shape. Various IEDF shapes can be generated, each associated with a different ion energy and IEDF width. For example, a first IEDF shape can be a delta function, while a second IEDF shape can be a square function. Another IEDF shape can be cup-shaped. Examples of various IEDF shapes can be seen in FIG. 11.

[0175] Ion current I I With knowledge of ρ and the voltage step ΔV, Equation 4 can be solved for ion energy eV. The voltage step ΔV can be controlled by changing the power supply voltage, which in turn changes the voltage step ΔV. A larger power supply voltage causes an increase in the voltage step ΔV, and a decrease in the power supply voltage causes a decrease in the voltage step ΔV. In other words, increasing the power supply voltage results in a larger ion energy eV.

[0176] Furthermore, because the above systems and methods operate on a continuously varying feedback loop, the desired (or defined) ion energy and IEDF width can be maintained despite changes in the plasma due to variations or intentional adjustments to the plasma source or chamber conditions.

[0177] 30-41 are described in terms of a single ion energy, those skilled in the art will recognize that these methods of generating and monitoring a desired (or defined) IEDF width (or IEDF shape) and ion energy may also be utilized to produce and monitor two or more ion energies, each having its own respective IEDF width (or IEDF shape). For example, if the first power supply voltage V PS By providing a second power supply voltage on the second, fourth, and sixth cycles, two distinctly different narrow ion energies can be achieved for ions reaching the surface of the substrate (e.g., FIG. 42A). Using three different power supply voltages results in three different ion energies (e.g., FIG. 42B). By varying the time each of the multiple power supply voltages is applied or the number of cycles each power supply voltage level is applied, the ion flux of different ion energies can be controlled (e.g., FIG. 42C).

[0178] The above discussion illustrates how a periodic voltage function provided by a power supply, in combination with ion current compensation provided by an ion current compensation component, can be used to control the ion energy and IEDF width and / or IEDF shape of ions reaching the surface of a substrate during plasma processing.

[0179] Some of the control described above is made possible by using some combination of (1) a fixed waveform (where the waveform cycle duration is identical), (2) a waveform with at least two portions proportional to ion energy and IEDF (e.g., third and fourth portions 1406 and 1408 illustrated in FIG. 14), and (3) a high sampling rate (e.g., 125 MHz) that allows accurate monitoring of distinct features of the waveform. For example, when prior art such as linear amplifiers transmit waveforms to the substrate that resemble a modified periodic voltage function, undesirable cycle-to-cycle variations make it difficult to use these prior art waveforms to characterize ion energy or IEDF width (or IEDF shape).

[0180] When a linear amplifier is used to bias the substrate support, the need to sample at a high rate is not recognized because the waveform is not consistent from cycle to cycle, and therefore resolving waveform features (e.g., partial slopes between pulses) would typically not provide useful information that does not arise when fixed waveforms are used, as in this and related disclosures.

[0181] The fixed waveform and high sampling rate disclosed herein further lead to more accurate statistical observations. This increased accuracy allows for monitoring of plasma operation and processing characteristics within the plasma source and chamber through monitoring various characteristics of the modified periodic voltage function. For example, measurement of the modified periodic voltage function allows for remote monitoring of sheath capacitance and ion current, which can be monitored without knowledge of the chamber process or other chamber details. Several examples follow to illustrate only a few of the many ways in which the systems and methods described thus far can be used for non-invasive monitoring and fault detection of sources and chambers.

[0182] As a monitoring example, referring to FIG. 14, the DC offset of waveform 1400 can indicate the health of the plasma source (hereafter referred to as the "source"). In another example, the slope of the top portion 1404 (second portion) of the pulses of the modified periodic voltage function can be correlated to damping effects within the source. The standard deviation of the slope of top portion 1404 from horizontal (illustrated as having a slope equal to 0) is another way to monitor the health of the source based on one aspect of waveform 1400. Another aspect is the V sampled along the fourth portion 1408 of the modified periodic voltage function. out This involves measuring the standard deviation of the points and correlating the standard deviation to chamber resonances. For example, if this standard deviation is monitored during a sustained pulse and the standard deviation increases over time, this may indicate that there is resonance in the chamber, for example, in the electrostatic chuck. Resonance may be an indication of a poor electrical connection to or within the chamber, or additional unwanted inductance or capacitance.

[0183] 32 illustrates two modified periodic voltage function waveforms delivered to a substrate support according to one embodiment of the present disclosure. When compared, the two modified periodic voltage functions can be used for chamber matching or in-situ anomaly or fault detection. For example, one of the two modified periodic voltage functions can be a reference waveform, and the second function can be obtained from a plasma processing chamber during calibration. To calibrate a plasma processing chamber, the difference between the two modified periodic voltage functions (e.g., peak-to-peak voltage V PP Alternatively, the second modified periodic voltage function can be compared to the reference waveform during processing, and any difference (e.g., deviation) in the waveform characteristics may indicate a fault (e.g., a difference in the slope of the fourth portion 3202 of the modified periodic voltage function).

[0184] 33 illustrates an ion current waveform, which may indicate instability in the plasma source or changes in plasma density. Ion current I, such as that illustrated in FIG. IThe fluctuations in ion current I can be analyzed to identify faults and anomalies in the system. For example, the periodic fluctuations in Figure 33 may indicate low-frequency instabilities in the plasma source (e.g., plasma power supply 102). I Fluctuations in the ion current I can also indicate periodic changes in the plasma density. This indicator and the possible faults or anomalies it can indicate are particularly advantageous in that it I This is just one of many ways in which remote monitoring can be used.

[0185] FIG. 34 shows the ionic current I of a modified periodic voltage function waveform with a non-periodic shape. I The ion current I I This embodiment may indicate non-periodic fluctuations such as plasma source instabilities or changes in plasma density. Such fluctuations may also indicate various plasma instabilities such as arcing, parasitic plasma formation, or drift in plasma density.

[0186] 35 illustrates a modified periodic voltage function waveform that may indicate a fault in the bias supply. The top portion (also referred to as the second portion) of the third illustrated cycle shows anomalous behavior that may indicate a resonance in the bias supply (e.g., power supply 1206 of FIG. 12). This resonance may be an indication of a fault in the bias supply. Further analysis of the resonance may identify characteristics that are useful in identifying faults in the power system.

[0187] 36 illustrates modified periodic voltage function waveforms that may indicate dynamic (or nonlinear) changes in system capacitance. For example, stray capacitance that depends nonlinearly on voltage may result in such a modified periodic voltage function. In another example, plasma breakdown or failure in the chuck may also result in such a modified periodic voltage function. In each of the three illustrated cycles, nonlinearity in the fourth portion 3602 of each cycle may indicate dynamic changes in system capacitance. For example, the nonlinearity may indicate changes in sheath capacitance, since other components of the system capacitance are largely fixed.

[0188] 37 illustrates a modified periodic voltage function waveform that may indicate changes in plasma density. The illustrated modified periodic voltage function exhibits monotonic shifts in slope dV / dt, which may indicate changes in plasma density. These monotonic shifts can provide a direct indication of a predicted event, such as a process etch endpoint. In other embodiments, these monotonic shifts can indicate a process failure where no predicted event exists.

[0189] FIG. 38 illustrates sampling of ion current for different process runs, where drift in ion current can indicate system drift. Each data point can represent the ion current for a given run, with tolerance limits being user-defined or automatic limits that define the allowable ion current. A drift in ion current that gradually pushes the ion current above the tolerance limit can indicate that substrate damage may be occurring. This type of monitoring can also be combined with any number of other conventional monitoring, such as optical sieving, thickness measurement, etc. In addition to monitoring ion current drift, these conventional types of monitoring can enhance existing monitoring and statistical control.

[0190] FIG. 39 illustrates sampling of ion current for different process parameters. In this illustration, ion current can be used as a figure of merit to distinguish between different processes and different process characteristics. Such data can be used in plasma recipe and process development. For example, the 11 process conditions resulting in the 11 illustrated ion current data points can be tested, and the process resulting in the preferred ion current can be selected as the ideal process, or alternatively, as the preferred process. For example, the lowest ion current may be selected as the ideal process, and then the ion current associated with the preferred process can be used as a metric to determine whether the process is being performed using the preferred process conditions. This figure of merit can be used in addition to, or as a replacement for, similar traditional performance characteristics such as rate, selectivity, and profile angle, to name a few non-limiting examples.

[0191] 40 illustrates two modified periodic voltage functions monitored without plasma in the chamber. These two modified periodic voltage functions can be compared and used to characterize the plasma chamber. In an embodiment, the first modified periodic voltage function can be a reference waveform, while the second modified periodic voltage function can be a currently monitored waveform. These waveforms can be obtained without plasma in the processing chamber, for example, after chamber cleaning or preventative maintenance, and thus the second waveform can be used to provide verification of the chamber's electrical condition prior to releasing the chamber into (or back into) production.

[0192] FIG. 41 illustrates two modified periodic voltage functions that can be used to verify the validity of a plasma process. The first modified periodic voltage function can be a reference waveform, while the second modified periodic voltage function can be a currently monitored waveform. The currently monitored waveform can be compared to the reference waveform, and any differences can indicate parasitic and / or non-parasitic impedance problems that would not otherwise be detectable using conventional monitoring methods. For example, resonances seen on the waveforms of FIG. 35 can be detected and used to indicate resonances in the power supply.

[0193] Ion current compensation Ic, ion current I I , and / or sheath capacitance C sheath Any of the measurements illustrated in FIGS. 32-41 can be monitored while the method 3000 cycles to update each ion current I. I After the sample is taken in FIG. 38, the method 3000 calculates the updated ion current I I In another embodiment, the monitoring operation may result in the ion current I I , ion energy eV, or IEDF width may be desired. The corresponding corrections can be made, and the method 3000 can return to sampling 3004 to find a new ion current compensation I that satisfies Equation 3.

[0194] Those skilled in the art will recognize that the methods illustrated in Figures 30, 31, and 43 do not require any particular or described order of operations or are not limited to any order depicted or suggested by the figures. For example, measurements (Figures 32-41) can be monitored before, during, or after setting and monitoring the IEDF width and / or ion energy eV.

[0195] 44 illustrates various waveforms at different points in the system disclosed herein. The illustrated switching pattern 4410 for the switching components of the switch mode power supply, the power supply voltage VPS 4406 (also referred to herein as the periodic voltage function), the ion current compensation Ic 4404, the modified periodic voltage function 4402, and the substrate voltage V sub Given 4412, the IEDF has the illustrated width 4414 (which may not be drawn to scale) or IEDF shape 4414. This width is wider than what this disclosure refers to as a "narrow width." As shown, the ion current compensation Ic 4404 is proportional to the ion current I I When the substrate voltage V sub The IEDF width 4412 is not constant. The IEDF width 4414 varies with the substrate voltage V sub It is proportional to the voltage difference of the slope between the voltage reversals of 4412.

[0196] Given this non-narrow IEDF width 4414, the method disclosed herein C =I I ion current compensation Ic is adjusted until (or alternatively related according to Equation 2). I 1 illustrates the effect of producing a final incremental change in ion current compensation Ic to match I C =I I When the substrate voltage V sub 4512 remains substantially constant and the IEDF width 4514 transitions from non-narrow to narrow.

[0197] Once a narrow IEDF is achieved, the ion energy can be adjusted to a desired or defined value, as illustrated in Figure 46, where the power supply voltage (or alternatively the bus voltage V of a switch mode power supply) bus ) is reduced in magnitude (e.g., the maximum negative swing of the power supply voltage 4606 during the voltage reversal is reduced). As a result, ΔV1 is reduced when the peak-to-peak voltage is V PP1 From V PP2 As the substrate voltage V sub The magnitude of 4608 is reduced, thus reducing the magnitude of the ion energy from 4615 to 4614 while maintaining a narrow IEDF width.

[0198] Whether the ion energy is adjusted or not, after a narrow IEDF width is achieved, the IEDF width can be widened as shown in FIG. 47, where I I =I C (or alternatively I I and I C Given equation 2, which gives the relationship between C can be adjusted, thus changing the slope of the pulse-to-pulse portion of the modified periodic voltage function 4702. The ion current compensation Ic and the ion current I I As a result of the unequal IEDFs, the substrate voltage transitions from substantially constant to non-constant. A further consequence is that the IEDF width 4714 expands from a narrow IEDF 4714 to a non-narrow IEDF 4702. C I I The further away it is adjusted, the larger the IEDF4714 width.

[0199] 48 illustrates one pattern of power supply voltages that may be used to achieve more than one ion energy level, each ion energy level having a narrow IEDF 4814 width. The magnitude of the power supply voltage 4806 alternates every cycle. This results in an alternating ΔV and peak-to-peak voltage every cycle of the modified periodic voltage function 4802. The substrate voltage 4812, in turn, has two substantially constant voltages (or sustaining voltages) that alternate between pulses of the substrate voltage. This results in two different ion energies, each with a narrow IEDF 4814 width.

[0200] 49 illustrates another pattern of power supply voltages that can be used to achieve more than one ion energy level, with each ion energy level having a narrow IEDF 4914 width. Here, the power supply voltage 4906 alternates between two different magnitudes, but does so for two cycles at a time before alternating. As shown, the average ion energy is V PS4906 are alternated every cycle. This means that to achieve the same ion energy, V PS This is just one example of how various other patterns of 4906 can be used.

[0201] FIG. 50 shows the power supply voltage V that can be used to generate the defined IEDF5014. PS 5006 and Ion Current Compensation I C 5004, where alternating power supply voltages 5006 result in two different ion energies. In addition, the ion current I I By adjusting the ion current compensation 5004 away from V, the IEDF 5014 width for each ion energy can be expanded. If the ion energies are close enough together, as in the illustrated embodiment, the IEDFs 5014 for both ion energies will overlap, resulting in one large IEDF 5014. While other implementations are possible, this implementation uses V to achieve a defined ion energy and a defined IEDF 5014. PS 5006 and I C It is intended to show how combinations of adjustments to 5004 can be used.

[0202] Although the term "monoenergetic ion energy distribution" is used throughout this disclosure, it will be understood by those skilled in the art that in practice there may be some small finite width for the ion energy distribution despite the use of a constant or substantially constant substrate surface voltage. Thus, the term "controllable narrow or monoenergetic distribution of ion energies" is used to refer to the narrowest ion energy distribution possible via the systems and methods disclosed herein.

[0203] 17A and 17B, block diagrams depicting other embodiments of the present invention are shown. As shown, the substrate support 1708 in these embodiments includes an electrostatic chuck 1782, and an electrostatic chuck supply 1780 is utilized to apply power to the electrostatic chuck 1782. In some variations, as depicted in FIG. 17A, the electrostatic chuck supply 1780 is positioned to apply power directly to the substrate support 1708, while in other variations, the electrostatic chuck supply 1780 is positioned to apply power in conjunction with a switch-mode power supply. Note that in-line chucking can be delivered by a separate source or through the use of a controller, resulting in a net DC chucking function. This DC-coupled (e.g., no blocking capacitor) in-line chucking function can minimize undesired interference with other RF sources.

[0204] 18 is a block diagram depicting yet another embodiment of the present invention in which a plasma power supply 1884, which generally functions to generate plasma density, is also configured to drive a substrate support 1808 along with a switch-mode power supply 1806 and an electrostatic chuck supply 1880. In this implementation, the plasma power supply 1884, the electrostatic chuck supply 1880, and the switch-mode power supply 1806 may each reside in a separate assembly, or two or more of the sources 1806, 1880, 1884 may be constructed to reside in the same physical assembly. Advantageously, the embodiment depicted in FIG. 18 electrically grounds the upper electrode 1886 (e.g., a showerhead) to achieve electrical symmetry, allowing for reduced damage levels due to fewer arcing events.

[0205] 19, a block diagram depicting yet another embodiment of the present invention is shown. As depicted, a switch-mode power supply 1906 in this embodiment is configured to apply power to the substrate support and chamber 1904 to bias the substrate and ignite (and sustain) a plasma without the need for an additional plasma power supply (e.g., without plasma power supplies 102, 202, 1202, 1702, 1884). For example, the switch-mode power supply 1806 can be operated at a duty cycle that is sufficient to provide a bias to the substrate support while igniting and sustaining a plasma.

[0206] Referring now to Figure 20, a block diagram of input parameters and control outputs of a control portion that may be utilized in connection with the embodiments described with reference to Figures 1-19 is depicted. The depiction of the control portion is intended to provide a simplified depiction of example control inputs and outputs that may be utilized in connection with the embodiments discussed herein; i.e., it is not intended to be a hardware schematic. In an actual implementation, the depicted control portion may be distributed among several discrete components that may be realized by hardware, software, firmware, or a combination thereof.

[0207] With reference to embodiments previously discussed herein, the controller depicted in FIG. 20 may provide the functionality of one or more of the controller 112 described with reference to FIG. 1, the controller 212 and ion energy control 220 components described with reference to FIG. 2, the controller 812 and ion energy control portion 820 described with reference to FIG. 8, the ion current compensation component 1260 described with reference to FIG. 12, the current controller 1362 described with reference to FIG. 13, the Icc control depicted in FIG. 16, the controllers 1712A, 1712B depicted in FIGS. 17A and 17B, respectively, and the controllers 1812, 1912 depicted in FIGS. 18 and 19, respectively.

[0208] As shown, parameters that may be utilized as inputs to the control portion include dVo / dt and ΔV, which will be described in more detail with reference to FIGS. 13 and 14. As discussed, dVo / dt may be utilized in conjunction with an ion energy distribution spread input ΔE to provide a control signal Icc that controls the width of the ion energy distribution spread, as will be described with reference to FIGS. 12, 13, 14, 15A-C, and 16. Additionally, an ion energy control input (Ei) may be utilized in conjunction with an optional feedback ΔV to provide an ion energy control signal (e.g., V depicted in FIG. 3) as will be described in more detail with reference to FIGS. 1-11. bus (affecting the ion energy distribution) to produce a desired (defined) ion energy distribution. Another parameter that may also be utilized in connection with many electrostatic chuck embodiments is a DC offset input, which provides the electrostatic force to hold the wafer to the chuck for efficient thermal control.

[0209] 21 illustrates a plasma processing system 2100 according to an embodiment of the present disclosure. The system 2100 includes a plasma processing chamber 2102 that contains a plasma 2104 for etching an upper surface 2118 of a substrate 2106 (and other plasma processes). The plasma is generated (e.g., in situ, remote, or projected) by a plasma source 2112 that is powered by a plasma power supply 2122. The plasma sheath voltage V measured between the plasma 2104 and the upper surface 2118 of the substrate 2106 is sheath The plasma 2104 accelerates ions from the plasma 2104 across the plasma sheath 2115, causing the accelerated ions to strike the upper surface 2118 of the substrate 2106 and etch the substrate 2106 (or portions of the substrate 2106 not protected by photoresist). The plasma 2104 is at a plasma potential V3 relative to ground (e.g., the plasma processing chamber 2102 walls). The substrate 2106 is at a chuck potential V3 between the electrostatic chuck 2111 and the upper surface 2121 of the electrostatic chuck 2111 and the substrate 2106. chuckThe substrate 2106 has a bottom surface 2120 that is electrostatically held to the support 2108 via a first potential V1 at the top surface 2118 and a second potential V2 at the bottom surface 2120. The top surface of the electrostatic chuck 2121 contacts the bottom surface 2120 of the substrate, and therefore these two surfaces 2120, 2121 are at the same potential V2. The first potential V1, the chuck potential V chuck , and second potential V2 are controlled via an AC waveform with a DC bias or offset generated by the switch-mode power supply 2130 and provided to the electrostatic chuck 2111 via a first conductor 2124. Optionally, an AC waveform is provided via the first conductor 2124 and a DC waveform is provided via an optional second conductor 2125. The AC and DC outputs of the switch-mode power supply 2130 can likewise be controlled via a controller 2132 configured to control various aspects of the switch-mode power supply 2130.

[0210] The ion energy and ion energy distribution are a function of the first potential V1. The switch-mode power supply 2130 provides an AC waveform adjusted to produce a desired first potential V1 known to generate a desired (or defined) ion energy and ion energy distribution. The AC waveform can be RF and have a non-sinusoidal waveform such as those illustrated in Figures 9B, 10B, 14, 32, 37, 40, 41, and 44-50. The first potential V1 can be proportional to the change in voltage ΔV illustrated in Figure 14. The first potential V1 also varies the voltage from the plasma voltage V3 to the plasma sheath voltage V sheath However, the plasma voltage V3 is often equal to the plasma sheath voltage V sheath (e.g., 50 V-2000 V) because the first potential V1 and the plasma sheath voltage V sheath are approximately equal and can be treated as equal for implementation purposes. Therefore, the plasma sheath voltage V sheathSince V controls the ion energy, the first potential V is proportional to the ion energy distribution. By maintaining a constant first potential V (or a substantially constant voltage portion or sustained voltage portion), the plasma sheath voltage V sheath becomes constant (or substantially constant or continuous), and therefore substantially all ions are accelerated through the same energy, and thus a narrow ion energy distribution is achieved. The plasma voltage V3 results from the energy imparted to the plasma 2104 via the plasma source 2112.

[0211] A first potential V1 at the upper surface 2118 of the substrate 2106 is formed through a combination of capacitive charging from the electrostatic chuck 2111 and charge accumulation from electrons and ions passing through the sheath 2115. The AC waveform from the switch-mode power supply 2130 is adjusted to offset the effects of ion and electron movement through the sheath 2115 and the resulting charge accumulation at the upper surface 2118 of the substrate 2106 so that the first potential V1 remains substantially constant (or continuous).

[0212] The chucking force that holds the substrate 2106 to the electrostatic chuck 2111 is the chucking potential V chuck The switch-mode power supply 2130 provides a DC bias, i.e., a DC offset, to the AC waveform so that the second potential V2 is at a different potential than the first potential V1. This potential difference is a function of the chuck voltage V chuck The chuck voltage V chuck may be measured from the top surface 2221 of the electrostatic chuck 2111 to a reference layer inside the substrate 2106, including at any elevation inside the substrate except the bottom surface 2120 of the substrate 2106 (the exact location within the substrate 2106 of the reference layer may vary). The chuck is therefore controlled by and proportional to the second potential V2.

[0213] In one embodiment, the second potential V2 is equal to the DC offset of the switched-mode power supply 2130 that is modified by an AC waveform (in other words, an AC waveform with a DC offset, where the DC offset exceeds the peak-to-peak voltage of the AC waveform). The DC offset may be substantially larger than the AC waveform so that the DC component of the output of the switched-mode power supply 2130 dominates the second potential V2 and the AC component may be excluded or ignored.

[0214] The potential within the substrate 2106 varies between the first and second potentials V1, V2. The chuck potential V chuck is positive or negative (e.g., V1 > V2 or V1 < V2) because the Coulomb attraction between the substrate 2106 and the electrostatic chuck 2111 exists regardless of the polarity of the chuck potential V chuck .

[0215] The switched-mode power supply 2130 can be used in combination with the controller 2132 to monitor various voltages deterministically and without sensors. In particular, the ion energy (e.g., average energy and ion energy distribution) is monitored deterministically based on the parameters of the AC waveform (e.g., slope and step). For example, the plasma voltage V3, ion energy, and ion energy distribution are proportional to the parameters of the AC waveform produced by the switched-mode power supply 2130. In particular, the ΔV of the falling edge of the AC waveform (see, e.g., FIG. 14) is proportional to the first potential V1 and thus the ion energy. By maintaining the first potential V1 constant (or a substantially constant voltage portion or holding voltage portion), the ion energy distribution is maintained within a narrow range.

[0216] If the first potential V1 cannot be measured directly and the correlation between the switch-mode power supply output and the first voltage V1 may vary based on the capacitance of the substrate 2106 and process parameters, the proportionality constant between ΔV and the first potential V1 can be determined experimentally after a short processing time. For example, if the falling edge ΔV of the AC waveform is 50 V and the proportionality constant is experimentally found to be 2 for a given substrate and process, the first potential V1 can be expected to be 100 V. The proportionality between the voltage step ΔV and the first potential V1 (and thus the ion energy eV) is expressed by Equation 4. Therefore, the first potential V1 with ion energy and the ion energy distribution can be determined based on knowledge of the AC waveform of the switch-mode power supply without any sensors inside the plasma processing chamber 2102. Additionally, the switch mode power supply 2130, in conjunction with the controller 2132, determines whether chucking is occurring (e.g., whether the substrate 2106 is at a chucking potential V chuck Whether the workpiece is being held by the electrostatic chuck 2111 or not can be monitored via the

[0217] Dechucking is performed at a chuck potential V chuck This can be done by setting the second potential V2 equal to the first potential V1. In other words, the DC offset and AC waveform are chuckcan be adjusted to approach 0V. Compared to conventional dechucking methods, the system 2100 achieves faster dechucking, and therefore higher throughput, because both the DC offset and AC waveform can be adjusted to achieve dechucking. Also, when the DC and AC power sources are in the switch-mode power supply 2130, the circuits are more integrated, closer together, and controlled via a single controller 2132 (compared to a typical parallel arrangement of DC and AC power sources), allowing for faster output changes. The dechucking speed enabled by the embodiments disclosed herein also allows for dechucking after the plasma 2104 has been extinguished, or at least after power from the plasma source 2112 has been turned off.

[0218] The plasma source 2112 can take a variety of forms. For example, in one embodiment, the plasma source 2112 includes electrodes inside the plasma processing chamber 2102 that establish an RF field within the chamber 2102 that both ignites and sustains the plasma 2104. In another embodiment, the plasma source 2112 includes a remotely projected plasma source that remotely generates an ionizing electromagnetic field, projects or extends the ionizing electromagnetic field into the processing chamber 2102, and uses the ionizing electromagnetic field to both ignite and sustain the plasma 2104 within the plasma processing chamber. Additionally, a remotely projected plasma source also includes a field transfer section (e.g., a conductive tube) through which the ionizing electromagnetic field passes on its way to the plasma processing chamber 2102, during which the ionizing electromagnetic field is attenuated so that the field strength within the plasma processing chamber 2102 is only a tenth, a hundredth, a thousandth, or even a smaller fraction of the field strength when the field is initially generated in the remotely projected plasma source. Plasma source 2112 is not drawn to scale.

[0219] The switch-mode power supply 2130 can be floating and therefore biased with any DC offset by a DC power supply (not shown) connected in series between ground and the switch-mode power supply 2130. The switch-mode power supply 2130 can provide a DC offset to the AC waveform either via AC and DC power supplies internal to the switch-mode power supply 2130 (see, e.g., FIGS. 22, 23, 26) or via an AC power supply internal to the switch-mode power supply 2130 and a DC power supply external to the switch-mode power supply 2130 (see, e.g., FIGS. 24, 27). In an embodiment, the switch-mode power supply 2130 can be grounded and coupled in series to a floating DC power supply coupled in series between the switch-mode power supply 2130 and the electrostatic chuck 2111.

[0220] The controller 2132 can control the AC and DC outputs of the switch-mode power supply 2130 when the switch-mode power supply 2130 includes both an AC and a DC power source. When the switch-mode power supply 2130 is connected in series with a DC power source, the controller 2132 may control only the AC output of the switch-mode power supply 2130. In alternative embodiments, the controller 2130 can control both the switch-mode power supply 2130 and a DC power source coupled to the switch-mode power supply 2130. Those skilled in the art will recognize that although a single controller 2132 is illustrated, other controllers can also be implemented to control the AC waveform and DC offset provided to the electrostatic chuck 2111.

[0221] The electrostatic chuck 2111 can be a dielectric (e.g., ceramic) and therefore can substantially block the passage of DC voltages, or can be a semiconducting material such as a doped ceramic. In either case, the electrostatic chuck 2111 can have a second voltage V2 on its upper surface 2121 that capacitively couples a voltage to the (typically dielectric) upper surface 2118 of the substrate 2106, forming a first voltage V1.

[0222] The plasma 2104 shape and size are not necessarily drawn to scale. For example, the edge of the plasma 2104 can be defined by a certain plasma density, and the illustrated plasma 2104 is not drawn with any particular plasma density in mind. Similarly, at least some plasma density fills the entire plasma processing chamber 2102 regardless of the illustrated plasma 2104 shape. The illustrated plasma 2104 shape is intended primarily to show the sheath 2115, which has a plasma density substantially less than the plasma 2104.

[0223] 22 illustrates another embodiment of a plasma processing system 2200. In the illustrated embodiment, a switch-mode power supply 2230 includes a DC power supply 2234 and an AC power supply 2236 connected in series. A controller 2232 is configured to control the AC waveform via a DC offset output of the switch-mode power supply 2230 by controlling both the AC power supply 2236 waveform and the DC power supply 2234 bias or offset. This embodiment also includes an electrostatic chuck 2211 having a grid or mesh electrode 2210 embedded within the chuck 2211. The switch-mode power supply 2230 provides both an AC and a DC bias to the grid electrode 2210. The DC bias, with an AC component that is substantially less than the DC bias and can therefore be eliminated, establishes a third potential V4 on the grid electrode 2210. When the third potential V4 differs from the potential at a reference layer anywhere within the substrate 2206 (excluding the bottom surface 2220 of the substrate 2206), the chuck potential V chuck and a Coulomb chucking force is established, holding the substrate 2206 to the electrostatic chuck 2211. The reference plane is an imaginary plane parallel to the grid electrode 2210. An AC waveform capacitively couples from the grid electrode 2210, through a portion of the electrostatic chuck 2211, and through the substrate 2206 to control a first potential V1 on the upper surface 2218 of the substrate 2206. The plasma potential V3 is determined by the plasma sheath voltage V sheathSince the first potential V1 and the plasma sheath voltage V sheath are approximately equal and are considered equal for practical purposes. Thus, the first potential V1 is equal to the potential used to accelerate ions through the sheath 2215.

[0224] In one embodiment, the electrostatic chuck 2211 may be doped to be sufficiently conductive so that any potential difference across the body of the chuck 2211 can be eliminated, and therefore the grid or mesh electrode 2210 may be at substantially the same voltage as the second potential V2.

[0225] A grid electrode 2210 is embedded in the electrostatic chuck 2211, parallel to the substrate 2206, and biased by a switch-mode power supply 2230 to provide a chuck potential V chuck The grid electrode 2210 can be any conductive planar device configured to establish a potential difference (V) between the substrate 2206 and the grid electrode 2210. While the grid electrode 2210 is illustrated as being embedded in a lower portion of the electrostatic chuck 2211, the grid electrode 2210 can be located closer or farther from the substrate 2206. The grid electrode 2210 also need not have a grid pattern. In some embodiments, the grid electrode 2210 can be a solid electrode or have a non-solid structure with a non-grid shape (e.g., a checkerboard pattern). In some embodiments, the electrostatic chuck 2211 is a ceramic or other dielectric, and therefore the third potential V4 on the grid electrode 2210 is not equal to the first potential V1 on the top surface 2221 of the electrostatic chuck 2211. In another embodiment, the electrostatic chuck 2211 is a doped ceramic that is slightly conductive, and therefore the third potential V4 on the grid electrode 2210 can be equal to the second potential V2 on the top surface 2221 of the electrostatic chuck 2211.

[0226] The switch-mode power supply 2230 generates an AC output, which may be non-sinusoidal. The switch-mode power supply 2230 is capable of operating the DC and AC sources 2234, 2236 in series because the DC power source 2234 is AC conductive and the AC power source 2236 is DC conductive. An example AC power source that is not DC conductive is a linear amplifier, which may be damaged if a DC voltage or current is provided. The use of AC and DC conductive power sources reduces the number of components used in the switch-mode power supply 2230. For example, if the DC power source 2234 provides AC blocking, an AC bypass or DC blocking component (e.g., a capacitor) may need to be arranged in parallel with the DC power source 2234. If the AC power source 2236 provides DC blocking, a DC bypass or AC blocking component (e.g., an inductor) may need to be arranged in parallel with the AC power source 2236.

[0227] In this embodiment, the AC power supply 2238 is generally configured to apply a voltage bias to the electrostatic chuck 2211 in a controllable manner to produce a desired (defined) ion energy distribution for ions bombarding the upper surface 2218 of the substrate 2206. More specifically, the AC power supply 2236 is configured to produce a desired (defined) ion energy distribution by applying one or more specific waveforms at specific power levels to the grid electrode 2210. Also, more specifically, the AC power supply 2236 applies specific power levels, produces specific ion energies, and applies the specific power levels using one or more voltage waveforms defined by waveform data stored in a waveform memory (not shown). As a result, one or more specific ion bombardment energies can be selected to perform controlled etching of the substrate 2206 (or other plasma-assisted process). In one embodiment, the AC power supply 2236 can utilize a switchable mode configuration (see, e.g., FIGS. 25-27). The switch mode power supply 2230, and in particular the AC power supply 2236, is capable of producing AC waveforms as described in various embodiments of the present disclosure.

[0228] Those skilled in the art will recognize that the grid electrode 2210 is not required and other embodiments can be implemented without the grid electrode 2210. Those skilled in the art will also recognize that the grid electrode 2210 is connected to the chuck potential V chuck It will be appreciated that this is just one example of many devices that may be used to establish a

[0229] 23 illustrates another embodiment of a plasma processing system 2300. The illustrated embodiment includes a switch-mode power supply 2330 for providing an AC waveform and a DC bias to an electrostatic chuck 2311. The switch-mode power supply 2330 includes a DC power supply 2334 and an AC power supply 2336, both of which may be grounded. The AC power supply 2336 generates an AC waveform that is provided to a first grid or mesh electrode 2310 embedded within the electrostatic chuck 2311 via a first conductor 2324. The AC power supply 2336 establishes a potential V4 on the first grid or mesh electrode 2310. The DC power supply 2334 generates a DC bias that is provided to a second grid or mesh electrode 2312 embedded within the electrostatic chuck 2311 via a second conductor 2325. The DC power supply 2334 establishes a potential V5 on the second grid or mesh electrode 2312. The potentials V4 and V5 can be independently controlled via AC and DC power supplies 2336 and 2334, respectively. However, the first and second grid or mesh electrodes 2310 and 2312 can also be capacitively coupled, and / or there can be DC coupling between the grid or mesh electrodes 2310 and 2312 through portions of the electrostatic chuck 2311. When either AC or DC coupling is present, the potentials V4 and V5 may be coupled. Those skilled in the art will recognize that the first and second grid electrodes 2310 and 2312 can be arranged in various locations throughout the electrostatic chuck 2311, including arranging the first grid electrode 2310 closer to the substrate 2306 than the second grid electrode 2312.

[0230] 24 illustrates another embodiment of a plasma processing system 2400. In this embodiment, a switch-mode power supply 2430 provides an AC waveform to an electrostatic chuck 2411, and the switch-mode power supply 2430 output is offset by a DC bias provided by a DC power supply 2434. The AC waveform of the switch-mode power supply 2430 has a waveform selected by a controller 2435 to bombard the substrate 2406 with ions from the plasma 2404 having a narrow ion energy distribution. The AC waveform can be non-sinusoidal (e.g., square wave or pulsed) and can be generated via an AC source 2436 of the switch-mode power supply 2430. The chuck is controlled via a DC offset from the DC power supply 2434, which is controlled by a controller 2433. The DC power supply 2434 can be coupled in series between ground and the switch-mode power supply 2430. The switch mode power supply 2430 is floating so that its DC bias can be set by the DC power supply 2434 .

[0231] Those skilled in the art will recognize that while the illustrated embodiment shows two independent controllers 2433, 2435, these may be combined into a single functional unit, device, or system, such as optional controller 2432. Additionally, controllers 2433 and 2435 may be coupled to communicate with each other and share processing resources.

[0232] 25 illustrates a further embodiment of a plasma processing system 2500. The illustrated embodiment includes a switch-mode power supply 2530 that produces an AC waveform that may have a DC offset provided by a DC power supply (not shown). The switch-mode power supply can be controlled via an optional controller 2535, including voltage and current controllers 2537, 2539. The switch-mode power supply 2530 can include a controllable voltage source 2538 having a voltage output controlled by the voltage controller 2537 and a controllable current source 2540 having a current output controlled by the current controller 2539. The controllable voltage and current sources 2538, 2540 can be in a parallel arrangement. The controllable current source 2540 is configured to compensate for ion current between the plasma 2504 and the substrate 2506.

[0233] The voltage and current controllers 2537, 2539 can be coupled to and in communication with each other. The voltage controller 2537 can also control the switched output 2539 of the controllable voltage source 2538. The switched output 2539 can include two switches in parallel, as shown, or can include any circuitry that converts the output of the controllable voltage source 2538 into a desired AC waveform (e.g., a non-sinusoidal wave). Through the two switches, the controlled voltage or AC waveform from the controllable voltage source 2538 can be combined with the controlled current output of the controllable current source 2540 to generate the AC waveform output of the switch mode power supply 2530.

[0234] The controllable voltage source 2538 is shown as having a given polarity, although one skilled in the art will recognize that the opposite polarity is equivalent to that shown. Optionally, the controllable voltage and current sources 2538, 2540, along with the switched output 2539, can be part of an AC power source 2536, which can be arranged in series with a DC power source (not shown) that is internal or external to the switched mode power supply 2530.

[0235] 26 illustrates yet another embodiment of a plasma processing system 2600. In the illustrated embodiment, a switch-mode power supply 2630 provides an AC waveform with a DC offset to an electrostatic chuck 2611. The AC component of the waveform is generated via a parallel combination of a controllable voltage source 2638 and a controllable current source 2640 connected together through a switched output 2639. The DC offset is generated by a DC power supply 2634 coupled in series between ground and the controllable voltage source 2638. In some embodiments, the DC power supply 2634 can be floating rather than grounded. Similarly, the switch-mode power supply 2630 can be floating or grounded.

[0236] The system 2600 can include one or more controllers for controlling the output of the switch-mode power supply 2630. A first controller 2632 can control the output of the switch-mode power supply 2630, for example, via a second controller 2633 and a third controller 2635. The second controller 2633 can control the DC offset of the switch-mode power supply 2630 as generated by the DC power supply 2634. The third controller 2635 can control the AC waveform of the switch-mode power supply 2630 by controlling a controllable voltage source 2638 and a controllable current source 2640. In an embodiment, a voltage controller 2637 controls the voltage output of the controllable voltage source 2638, and a current controller 2639 controls the current of the controllable current source 2640. The voltage and current controllers 2637, 2639 can communicate with each other and can be part of the third controller 2635.

[0237] Those skilled in the art will recognize that the foregoing embodiments describing various configurations of controllers for the power supplies 2634, 2638, 2640 are not limiting, and various other configurations can also be implemented without departing from this disclosure. For example, the third controller 2635 or the voltage controller 2637 can control the switched output 2639 between the controllable voltage source 2638 and the controllable current source 2640. As another example, the second and third controllers 2633, 2635 can be in communication with each other (although not shown as such). It should also be understood that the polarity of the controllable voltage and current sources 2638, 2640 is illustrative only and is not meant to be limiting.

[0238] The switched output 2639 can operate by alternating two parallel switches to shape the AC waveform. The switched output 2639 can include any of a variety of switches, including but not limited to MOSFETs and BJTs. In one variation, the DC power supply 2634 can be arranged between the controllable current source 2640 and the electrostatic chuck 2611 (in other words, the DC power supply 2634 can float), and the switch-mode power supply 2630 can be grounded.

[0239] 27 illustrates another embodiment of a plasma processing system 2700. In this variation, the switch-mode power supply 2734 is again grounded, but instead of being integrated into the switch-mode power supply 2730, the DC power supply 2734 is now a separate component that provides a DC offset to the entire switch-mode power supply 2730, and not just to components within the switch-mode power supply 2730.

[0240] FIG. 28 illustrates a method 2800 according to an embodiment of the present disclosure. The method 2800 includes placing a substrate in a plasma chamber operation 2802. The method 2800 further includes forming a plasma in the plasma chamber operation 2804. Such a plasma can be formed in situ or via a remote projection source. The method 2800 also includes a switch power operation 2806. The switch power operation 2806 involves controllably switching power to the substrate to apply a periodic voltage function to the substrate. The periodic voltage function can be considered a pulsed waveform (e.g., a square wave) or an AC waveform and can include a DC offset generated by a DC power source in series with the switch-mode power supply. In an embodiment, the DC power source can be integrated into the switch-mode power supply and therefore in series with the AC power source of the switch-mode power supply. The DC offset generates a potential difference between the top surface of the electrostatic chuck and a reference layer in the substrate; this potential difference is referred to as the chuck potential. A chucking potential between the electrostatic chuck and the substrate holds the substrate to the electrostatic chuck, thus preventing the substrate from moving during processing. Method 2800 further includes modulating operation 2808, in which the periodic voltage function is modulated over multiple cycles. The modulation is responsive to a desired (or defined) ion energy distribution at the surface of the substrate to result in a desired (or defined) ion energy distribution based on a time average.

[0241] 29 illustrates another method 2900 according to an embodiment of the present disclosure. Method 2900 includes placing a substrate in a plasma chamber operation 2902. Method 2900 further includes forming a plasma in the plasma chamber operation 2904. Such a plasma can be formed in situ or via a remote projection source. Method 2900 also includes receiving at least one ion energy distribution setting operation 2906. The setting received in receiving operation 2906 may indicate one or more ion energies at the surface of the substrate. Method 2900 further includes a switch power operation 2908 in which power to the substrate is controllably switched to provide (1) a desired (or defined) distribution of ion energy based on a time average, and (2) a desired chuck potential based on a time average. The power can have an AC waveform and a DC offset.

[0242] Control of surface charge accumulation During plasma processing, insulating elements can accumulate excess charge, resulting in possible damage to sensitive devices connected to these elements. In other cases, accumulated charge on insulating features can cause deflection of arriving ions, resulting in distortion of the structures being etched or deposited. These are just two of the problems that can result from excess charge accumulation. Conventional plasma processing systems lack the ability to directly measure and control surface charge during plasma processing.

[0243] Referring again to FIG. 14 , an asymmetric periodic voltage function is provided to the substrate support, generating a potential that biases the substrate and attracts ions from the plasma. The waveform undergoes a positive voltage rise, or ramp, at the beginning of period t, which, when applied to the substrate support in the presence of a plasma, attracts electrons to the substrate surface, resulting in the accumulation of negative charge. The power supply, which biases the substrate, may then provide only a small, if any, voltage or current for a first duration t1 until the beginning of a second duration t2. The first voltage drop, or ramp, produces a surface potential that causes positive ions to begin flowing from the plasma to the substrate surface. A second voltage ramp (with slope dv / dt) is then maintained for a second duration t2, causing the plasma sheath (capacitance C sheath At the end of the second duration t2, a positive voltage rise, or ramp, is again repeated to stop the flow of ions, replenish the negative surface charge, and begin the next cycle. When properly adjusted as explained above, the current measured during the second duration t2 is chuck This can allow the ionic current flowing during the second voltage ramp to be determined according to:

number

[0244] In other words, the ion current can be found as follows:

number

[0245] Knowledge of the ionic current is combined with knowledge of the second duration t2 to determine the total surface charge accumulation Q i can be resolved from the accumulation of ion current delivered to the substrate surface during a second duration t2. The total surface charge accumulation Q i can be found as follows:

number

[0246] To avoid excessive surface charge accumulation, the total surface charge accumulation Q i can be monitored and a second duration t2, i.e., the time during which ion current is flowing to the substrate, is monitored to determine the surface charge Q i can be modified or reduced until it meets a desired level or returns below a threshold that is deemed safe. The second duration t2 can be controlled by at least one or both of the repetition rate and the duty cycle.

[0247] FIG. 58 illustrates one embodiment of a system for plasma-based processing in which a power supply 5803 both controls ion energy distribution at the substrate surface and also prevents excessive surface charge accumulation. The system 5800 is similar to that described in FIG. 21 , and therefore only certain components will be described. The power supply 5803 can include a switch-mode power supply 5830 controlled via a controller 5832 (e.g., a switching controller). The switch-mode power supply 5830 provides an AC waveform at an output 5838 that is adjusted to produce a desired first potential V1 known to generate a desired (or defined) ion energy and ion energy distribution. The output 5838 can be configured for coupling to a substrate support 5808 of the processing chamber 5802. The AC waveform from the switch-mode power supply 5830 can be adjusted to offset the effects of ion and electron transport through the sheath 5815 and the resulting charge buildup at the top surface 5818 of the substrate 5806, so that the first potential V1 remains substantially constant (or continuous). The output 5838 combines contributions from the switch-mode power supply 5830 and the ion current compensation component 5836 to form an asymmetric periodic voltage waveform such as that shown in Figures 61-62.

[0248] The switch-mode power supply 5830, in conjunction with the controller 5832, can monitor various voltages deterministically and without sensors. In particular, the ion energy (e.g., average energy and ion energy distribution) is monitored deterministically based on parameters of the AC waveform (e.g., the slope dv / dt and step ΔV in FIG. 14 or the slope and step ΔV=Va-Vb of 6166 in FIG. 61). For example, the plasma voltage V3, ion energy, and ion energy distribution are proportional to parameters of the AC waveform produced by the switch-mode power supply 5830. In particular, the ΔV of the falling edge of the AC waveform, or the voltage drop, or the first negative voltage ramp (6164 in FIG. 61), is proportional to the first potential V1 and, therefore, the ion energy. By keeping the first potential V1 constant (or substantially constant or continuous), the ion energy distribution can be kept narrow or monoenergetic.

[0249] If the first potential V1 cannot be measured directly and the correlation between the switch-mode power supply output and the first voltage V1 may vary based on the capacitance of the substrate 5806 and process parameters, the constant of proportionality between ΔV and the first potential V1 can be determined experimentally after a short processing time has elapsed. For example, if the falling edge ΔV of the AC waveform is 50 V and the constant of proportionality is experimentally found to be 2 for a given substrate and process, the first potential V1 can be expected to be 100 V. The proportionality between the step voltage ΔV and the first potential V1 (and therefore the ion energy eV) is described by Equation 4. Therefore, the first potential V1 can be determined based on knowledge of the AC waveform of the switch-mode power supply, along with the ion energy and ion energy distribution, without any sensors inside the plasma processing chamber 5802.

[0250] Note that Figure 61 shows voltage waveforms similar to those seen in Figure 14, but with somewhat different nomenclature, different reference voltages, and sloped voltage ramps rather than the seemingly vertical voltage steps seen in Figure 14 (although some voltage rise and fall over a finite time period is implied in Figure 14 due to inherent inductive and capacitive loading in most circuits). For example, V in Figure 14 PP corresponds to ΔVa in FIG. 61. ΔVb in FIG. 61 corresponds to V in FIG. PP Corresponds to -ΔV.

[0251] The switch-mode power supply 5830 can be floating and therefore biased to any DC offset by a DC power supply (not shown) connected in series between ground and the switch-mode power supply 5830. The switch-mode power supply 5830 can provide a DC offset to the AC waveform either through AC and DC power supplies internal to the switch-mode power supply 5830 (see, e.g., FIGS. 22, 23, 26) or through an AC power supply internal to the switch-mode power supply 5830 and a DC power supply external to the switch-mode power supply 5830 (see, e.g., FIGS. 24, 27). In an embodiment, the switch-mode power supply 5830 can be grounded and coupled in series to a floating DC power supply that is coupled in series between the switch-mode power supply 5830 and the electrostatic chuck 5811.

[0252] The controller 5832 can control the AC and DC outputs of the switch-mode power supply 5830 when the switch-mode power supply 5830 includes both AC and DC power sources. When the switch-mode power supply 5830 is connected in series with a DC power source, the controller 5832 can control only the AC output of the switch-mode power supply 5830. In an alternative embodiment, the controller 5832 can control both the DC power source coupled to the switch-mode power supply 5830 and the switch-mode power supply 5830. Those skilled in the art will recognize that although a single controller 5832 is shown, other controllers can also be implemented to control the AC waveform and DC offset provided to the electrostatic chuck 5811.

[0253] The controller 5832 may be capable of controlling, in particular, the period and / or duty cycle of the asymmetric periodic voltage function generated by the switched-mode power supply 5830. This control may be particularly useful for controlling the second duration t2 and, hence, the charge Q on the substrate surface. i In some cases, both the period and duty cycle can be simultaneously adjusted to achieve a desired surface charge accumulation Q i can be modified to yield

[0254] Power supply 5803 may also include an ion current compensation component 5836 (either a current or voltage source or a power supply) electrically coupled to output 5838. Ion current compensation component 5836 tends to offset the effect of ion current, i.e., the tendency of ion current to counteract the bias voltage on the surface of the substrate. Ion current compensation component 5836 biases substrate 5806 via output 5838 for at least a second duration t2, thereby providing a second negative voltage ramp (e.g., the dv / dt region in FIG. 14 ).

[0255] The ion current compensation component can be configured to obtain a measurement of the ion current in the plasma processing chamber based on monitoring the current, voltage, or both between the output and the substrate for at least duration t2. As previously described, monitoring the voltage can allow the slope dv / dt during duration t2 to be known. Increasing the output of the ion current compensation component 5836 causes an increase in the magnitude of the negative slope dv / dt, while decreasing the output decreases the magnitude of the negative slope dv / dt. As previously discussed, the ion current compensation component 5836 not only controls its output, and therefore the slope dv / dt, but also controls the ion current I I This allows for the measurement of

[0256] Ion current I I Using the measurement of , the ion current compensation component 5836 also calculates the surface charge accumulation Q on the substrate 5806, for example, using either Equation 10 or 11. i can be estimated.

[0257] Surface charge accumulation Q i can be compared to a threshold or target range, and the surface charge accumulation Q i If Q is equal to or exceeds this threshold, or is outside the target range, the controller 5832 adjusts the surface charge accumulation Q i The second duration t2 can be adjusted via one of the various methods described above until the second duration t2 falls below the threshold or returns to within the target range.

[0258] In an embodiment, the controller 5805 in the ion current compensation component 5836 can perform the above comparison and then pass a command to the controller 5832 to adjust the second duration t2. Alternatively, the controller 5805 in the ion current compensation component 5836 can perform the above comparison and inform the controller 5832 of the results of the comparison, which can decide to adjust the second duration t2 in response to this data. In another alternative, the ion current compensation component 5836 can adjust the second duration t2 by comparing the surface charge accumulation Q i can be estimated and this data passed to controller 5832, which can perform a comparison and then determine whether and how to adjust second duration t2. These methods are reflected in Figures 65-67. Although controller 5832 is shown as part of power supply 5803, in other embodiments controller 5832 can be external to power supply 5803.

[0259] Referring to Figure 59, shown are aspects of an exemplary control system that may be used in connection with embodiments herein. Also shown is the sheath capacitance (C sheath ) and capacitance C1, which represent the intrinsic capacitances of the components associated with the plasma processing chamber 100 discussed throughout this disclosure, which may include an insulator, a substrate, a substrate support, and an electrostatic chuck.

[0260] As shown, the current and / or voltage may be measured by the controller 5960 to indirectly monitor one or more characteristics of the plasma processing chamber environment. Exemplary characteristics of the plasma processing chamber environment include sheath capacitance (C sheath ), which is the measured output voltage V out Another exemplary characteristic of the plasma processing chamber environment is the total surface charge accumulation Q i , which may be calculated using Equation 11. Power supply 5803 is one example of bias supply 5902.

[0261] The plasma can be monitored prior to processing a substrate to obtain stored data (e.g., about sheath capacitance and / or other characteristics of the plasma processing chamber environment), and the data can then be utilized to adjust the bias waveform (e.g., in a feedforward manner). Monitoring can also be performed during plasma processing, and adjustment of plasma parameters (e.g., by adjusting the voltage and / or duty cycle of the bias source 5902) can be made using real-time feedback, for example, using voltage and / or current measurements as shown in FIG.

[0262] Referring now to FIG. 60, shown is a general representation of an exemplary bias supply 6002 that may be used to implement the bias supplies of the present disclosure, including 5803. As shown, bias supply 6002 utilizes three voltages V1, V2, and V3. The output V out is C chuck Generally, V out There is no need to control the DC levels of V1, V2, or V3, and the three voltages can be reduced to two by selecting one of V1, V2, or V3 to be ground (0 V). A separate chuck supply may be used, so V out There is no need to control the DC levels of V. If a separate chuck supply is not used, all three voltages are V out The two switches S1 and S2 can be controlled to control the DC level of the inputs. Although not shown for clarity, the two switches S1 and S2 may be controlled by a switch controller via electrical or optical connections, allowing the switch controller to open and close the switches S1, S2, as disclosed below and discussed above. The depicted switches S1, S2 may be realized by single-pole / single-throw switches, and as a non-limiting example, the switches S1, S2 may be realized by silicon carbide metal oxide semiconductor field effect transistors (SiCMOSFETs).

[0263] In this implementation, the voltages V1, V2, and V3 may be DC source voltages. As shown, a first switch S1 couples a first voltage V1 to an output V out and a second switch S2 is arranged to switchably connect a second voltage V2 through the inductive element to the output V out In this implementation, the two switches connect to a common node 6070, and a common inductive element L1 connects the common node 6070 to the output node V out Other arrangements of inductive elements are also possible. For example, there may be two separate inductive elements, one connecting S1 to V out and another inductive element connects S2 to V out In another embodiment, one inductive element may connect S1 to S2, and another inductive element may connect either S1 or S2 to V out may be connected to

[0264] Referring to FIG. 60 and at the same time to FIG. 61, this is: 1) V out 6 depicts 1) a cycle of the asymmetric periodic voltage waveform (also referred to as a modified periodic voltage function in the preceding sections of this disclosure) of bias source 5202 output at 100 V, 2) the corresponding sheath voltage, and 3) the corresponding switch positions of switches S1 and S2. As shown, the periodic voltage waveform output by bias source 6002 is asymmetric such that the first half-cycle of the voltage waveform does not have a corresponding symmetric component during the second half-cycle of the voltage waveform. In operation, the first switch S1 is momentarily closed, causing a voltage drop across the output node V along a first portion 6160 of the voltage waveform (voltages V0-Va). out to a first voltage level Va. Level Va is maintained along a second portion 6162 of the waveform. The second switch S2 is then momentarily closed, increasing the level of the voltage at the output node V along a third portion 6164 of the waveform. out6164 to a second voltage level Vb. Note that S1 and S2 are open except for a short period of time. As shown, the negative voltage swing along the third portion 6164 reduces the sheath voltage (V sheath ). Thus, the magnitude of Va-Vb may be controlled to affect the sheath voltage and may be adjusted between different cycles of the voltage waveform to affect multiple ion energy peaks in the ion energy distribution function. The duration t2 between the opening of the second switch S2 and the closing of the first switch S1 determines the total surface charge accumulation Q i can be adjusted to control

[0265] In this embodiment, after the second switch S2 is opened and while the first and second switches S1 and S2 are open, a third voltage V3 is applied to the output node V through the second inductive element L2. out , further reducing the level of the voltage at the output node along a fourth portion 6166 of the voltage waveform (e.g., the dv / dt region of FIG. 14). Alternatively, the third voltage V3 can be applied throughout the entire operation of the switch, regardless of its open or closed state. In other words, the application of the third voltage V3 can have a duration that exceeds the second duration t2. As shown in FIG. 53, a negative voltage ramp along the fourth portion 6166 may be established to maintain the sheath voltage by compensating for ions impinging on the substrate. V3 can be applied only during the fourth portion 6166 or throughout the entire cycle of the periodic voltage waveform.

[0266] Therefore, S1 temporarily outputs a first voltage V1 through the first inductive element L1 to the output V out , and then disconnected, and after a period of time, S2 will provide a second voltage (e.g., ground) to the output V through the first inductive element L1. out A third voltage V3 is connected to the output V through the second inductive element L2. out In this implementation, the first voltage V1 may be higher than the third voltage V3, and the output Vout Temporarily connect and disconnect the output V out The voltage of the output increases to a first voltage level Va along a first portion 6160 of the voltage waveform, and the first voltage level Va is sustained along a second portion 6162 of the sustain waveform. The first voltage level Va may be greater than the first voltage V1, and a second voltage V2 (e.g., ground) may be less than the first voltage level Va. The momentary connection, then disconnection, of the second voltage V2 reduces the voltage of the output to a second voltage level Vb, below the second voltage V2 (e.g., ground), in a third portion 6164. Between the opening of the first switch S1 and the closing of the second switch S2, the bias supply may or may not attempt to control the voltage or current supplied to the substrate. However, in other embodiments, the bias supply may not provide any voltage, current, or power to the substrate support during this period between switch activities. In other words, the second portion of waveform 6162 may or may not be controlled by the bias supply.

[0267] As an example, as shown in Figure 62, V1 may be -2,000 V DC, V2 may be ground, V3 may be -5,000 V DC, V0 may be -7,000 V DC, Vb may be -3,000 V DC, and Va may be 3,000 V DC. However, these voltages are merely exemplary and to provide context for the relative magnitudes and polarities of the voltages described with reference to Figures 60 and 61.

[0268] Referring now to Figures 63A-63C, shown are possible arrangements of two DC voltage sources for providing the voltages V1, V2, and V3 depicted in Figures 61 and 62. In Figure 63A, V2 is grounded, forming a common node between the two DC voltage sources. In Figure 63B, V1 is grounded, and V2 forms a common node between the DC voltage sources. Also, in Figure 63C, V1 is grounded, forming a common node between each of the two DC voltage sources.

[0269] In some embodiments, as shown in Figures 64A, 64B, and 64C, three DC voltage sources may be utilized to apply three voltages V1, V2, and V3. As shown in Figure 64A, each of the three DC voltage sources may be coupled to ground, with each of the three DC voltage sources providing a corresponding one of V1, V2, and V3. In Figure 64B, one of the DC voltage sources is grounded, and the three DC voltage sources are arranged in series. In Figure 64C, one of the DC voltage sources is disposed between ground and V2, with each of the DC voltage sources coupled to V2.

[0270] Referring now to FIG. 65, shown is an exemplary bias supply 6502 that can be used to implement the bias supplies of the present disclosure, including 5803. As shown, the bias supply 6502 includes a switch controller 6504 and two voltage sources for providing a first voltage V1, a second voltage V2, and a third voltage V3. While not shown for clarity, two switches S1 and S2 are coupled to the switch controller 6504 (e.g., via electrical or optical connections), as disclosed below, allowing the switch controller 6504 to open and close the switches S1, S2. The depicted switches S1, S2 may be implemented by single-pole / single-throw, normally-open switches that are controllable by electrical or optical signals. As a non-limiting example, the switches S1, S2 may be implemented by silicon carbide metal oxide semiconductor field effect transistors (SiCMOSFETs).

[0271] Also shown is an exemplary controller 6560, which may be implemented within the housing of each bias supply or may be implemented as part of a centralized tool controller. As shown, the controller 6560 controls the output V of the bias supply. out, is coupled to receive information (e.g., voltage and / or current information) indicative of the power applied by bias source 6502 at t. As shown, controller 6560 is also coupled to switch controller 6504 and two DC voltage sources, such that controller 6560 controls bias source 6502 (e.g., controlling the plasma sheath adjacent to the bias electrode, the second duration t2, and hence the surface charge accumulation Q). i (controlling the

[0272] Additionally, the controller 6560 includes monitoring circuitry 6570 for measuring at least one characteristic of the power applied by the bias supply 6502 and a chamber analysis component 6573 configured to calculate characteristics of the environment within the plasma processing chamber based on the measured characteristic of the power obtained from the monitoring circuitry 6570. Also shown within the controller 6560 is control circuitry 6574 for regulating the power applied by the bias supply 6502 and controlling the plasma sheath adjacent to the bias electrode. While the controller 6560 and the switch controller 6504 are depicted as separate structures in FIG. 65, it should be appreciated that the controller 6560 and the switch controller 6504 may be integrated and / or share common underlying components. For example, the controller 6560 and the switch controller 6504 may be co-located on the same printed circuit board or system-on-chip (SoC). As another example, the controller 6560 and the switch controller may be realized by a system including an architecture similar to or identical to the computing device depicted in FIG. 70.

[0273] The monitoring circuitry 6570 may include one or more sensors, such as a directional coupler, a VI sensor, a phase and gain sensor, a voltage sensor, and a current sensor. As one skilled in the art would understand, the measured characteristics of the power may include voltage, current, phase, and power. Additionally, the monitoring circuitry 6570 may include analog-to-digital conversion components to convert analog signals from the sensors into digital representations of the measured characteristics of the power. In other implementations, the sensors are separate from the controller 6560, and the monitoring circuitry 6570 includes analog-to-digital conversion components to convert analog signals from the sensors into digital representations of the measured characteristics of the power. In yet other implementations, the sensors include sensing elements and analog-to-digital conversion components, and the monitoring circuitry 6570 may receive the digital representation of the characteristics of the power. Monitoring one or more characteristics of the environment of the plasma processing chamber may include measuring (using the monitoring circuitry 6570) at least one characteristic of the power applied by the at least one bias supply.

[0274] The chamber analysis component 6573 is generally configured to determine characteristics of the environment within the plasma processing chamber based on measured characteristics of the power obtained from the monitoring circuitry 6570. The power may be measured at a location external to the plasma processing chamber (by the monitoring circuitry 6570), and the measured power characteristics may be used to calculate characteristics of the environment within the plasma processing chamber. For example, using Equation 1, the ion current in the region proximate the bias zone may be calculated as V connecting C1: out As another example, Equation 2 may be used to calculate the sheath capacitance in the region adjacent to the bias zone. As yet another example, Equation 11 may be used to calculate the surface charge accumulation Q i can be used to determine

[0275] The control circuitry 6574 generally operates to adjust the power applied by the bias source and to adjust aspects of the environment within the plasma processing chamber. For example, the plasma sheath (established by the bias source 6502) adjacent to a zone may be adjusted, and / or the ion current may also be adjusted. As shown, the controller 6560 may be coupled to the DC voltage source and switch controller 6504. Thus, with reference to FIG. 61 , the controller 6560 may be used to adjust the voltage Va, the voltage Vb, the first duration t1, the second duration t2, the time T, and the slope of the fourth portion 6166. As discussed with reference to FIG. 61 , the voltage of the plasma sheath adjacent to the bias zone, associated with the bias source 6502, may be adjusted. The surface charge accumulation Q during the second duration t2 i can also be controlled by the controller 6560.

[0276] Referring again to FIG. 65, in this implementation (which incorporates the embodiment depicted in FIG. 63A), the second voltage V2 is provided to a node that is coupled to two DC voltage sources and coupled to ground, although in other implementations (e.g., as described above with reference to FIGS. 63B and 63C), the second voltage V2 need not be grounded. As shown, a first switch S1 is arranged to switchably connect the first voltage V1 to a common node 6571 (common to S1 and S2), and a second switch S2 is arranged to switchably couple the second voltage V2 to the common node 6571. Additionally, a first inductive element L1 couples the common node and the output node V out It is placed between.

[0277] In operation, the switch controller 6504 closes the first switch S1, providing a voltage at the output node V that is maintained along a first portion 6160 of the voltage waveform (voltages V0 to Va) and along a second portion 6162 of the waveform. outThe first switch S1 is then opened to increase the level of the voltage at the output node V along the third portion 6164 of the waveform. out The switch controller 6504 then opens the second switch S2 such that S1 and S2 are open. As shown, the negative voltage swing along the third portion 6164 reduces the sheath voltage (V sheath ) Therefore, the magnitude of Vb is out Vb may be controlled to affect the sheath voltage in close proximity to the electrode plane coupled to V. Those skilled in the art will appreciate that Vb is controllable by controlling V1, but Vb is not equal to V1 in this implementation due to the effect of inductor L1.

[0278] Controlling the second duration t2 between the opening of the second switch S2 and the closing of the first switch S1 controls the surface charge accumulation Q i can be controlled.

[0279] In this embodiment, the second voltage source functions as an ion compensation component and provides a third voltage V3 to the output node V through the second inductive element L2 at least while the first and second switches S1, S2 are open. out , further reducing the level of the voltage waveform at the output node along a fourth portion 6166 of the periodic asymmetric voltage waveform. As shown in FIG. 61, a negative voltage ramp along the fourth portion 6166 may be established to maintain, and optionally modify, the sheath voltage by compensating for ions impinging on the substrate. For example, the negative ramp voltage along the fourth portion 6166 can be adjusted to affect the width of the ion energy peak in the ion energy distribution function, and the duration t2 of the negative ramp voltage can be adjusted to affect the charge accumulation Q on the substrate. i can be used to control

[0280] Therefore, S1 temporarily outputs a first voltage V1 through the first inductive element L1 to the output V out , and then disconnected, and after a period of time, S2 will provide a second voltage (e.g., ground) to the output V through the first inductive element L1. out The third voltage V3 is connected to and then disconnected from the output V through the second inductive element L2. out In this implementation, the first voltage V1 may be higher than the third voltage V3, and the output V out Temporarily connect and disconnect the output V out The voltage at the output increases to a first voltage level Va along a first portion 6160 of the voltage waveform, and the first voltage level Va is sustained along a second portion of the waveform 5362. The first voltage level Va may be greater than the first voltage V1, and a second voltage V2 (e.g., ground) may be less than the first voltage level Va. The momentary connection, then disconnection, of the second voltage V2 reduces the voltage at the output in the third portion 6164 to a second voltage level Vb, which is below the second voltage V2 (e.g., ground).

[0281] In some embodiments, one or more bias sources may be used to measure ion density, sheath capacitance, or other chamber parameters with or without a reference substrate in the chamber. One or more processing steps may be performed, and then the measurements may be repeated. In this manner, changes to the chamber may be monitored.

[0282] If a silicon top lid is used, one or more bias sources 5803, 5960, 6002, and 6502 can be used to monitor regional ion density and / or other chamber parameters. Silicon top lids (also referred to as silicon vacuum seals) are typically consumable, but may not consume in a uniform manner. Measuring regional plasma characteristics using multiple bias sources 5803, 5960, 6002, and 6502 can provide a means for inferring non-uniformity changes in the silicon vacuum seal. This feedback over time can be used to adjust the RF source and / or bias sources 5803, 5960, 6002, and 6502 to account for time-varying non-uniformities in the silicon vacuum seal. Additionally, this feedback can be used to determine when the silicon vacuum seal may need to be replaced. In another embodiment, one or more bias sources 5803, 5960, 6002, and 6502 can be coupled to electrodes adjacent to the silicon vacuum seal (e.g., at the top of the chamber). Because bias sources 5803, 5960, 6002, and 6502 can be used to modify or even eliminate the plasma sheath, the present top-mounted bias sources 5803, 5960, 6002, and 6502 can be used to minimize or even eliminate the plasma sheath between the silicon vacuum seal and the plasma. In this way, erosion or wear of the silicon vacuum seal can be reduced compared to current processes.

[0283] Along these lines, bias sources 5803, 5960, 6002, and 6502 and corresponding electrodes can be arranged at various locations in the processing chamber to locally control the plasma sheath, thereby reducing or eliminating ion bombardment with certain regions or components of the chamber. Ion density and sheath capacitance and their local variations can be used to monitor chamber cleanliness. For example, changes in local ion density over time can indicate that a local chamber surface is accumulating one or more films. In another embodiment, multiple spatially distributed electrostatic chuck voltages can be used to affect regional ion density.

[0284] The present disclosure adjusts the second duration t2 to achieve a desired surface charge accumulation Q i Although the present invention focuses on providing a plasma with a high ion current I, in other embodiments, adjustments to the power supply that sustains the plasma can have a similar effect. In particular, the plasma density can be increased by adjusting the ion current I I and the surface charge accumulation is correlated with the ionic current I I Since the amount of power coupled into the plasma, and hence the plasma density, is a function of the surface charge accumulation Q i For example, feedback to a subsystem that controls plasma density, often referred to as the plasma source, can be used to control or maintain the surface charge accumulation Q i Therefore, both the plasma power as well as the duration of the second negative voltage ramp from the bias supply can be used to independently control the surface charge accumulation Q i At the same time, both the plasma source and the bias source can be used in combination to control the surface charge accumulation Q i (e.g., reducing the plasma power while also reducing the second duration t2).

[0285] FIG. 68 illustrates plots of the output voltage from the power supply (e.g., 5803), the substrate voltage, and the ion flux over different second durations t2. Varying the second duration t2 affects the IEDF (E ion ) but does not affect the position of the charge delivered during each cycle (Q i ) and therefore the nominal ion energy E ion without affecting the surface charge accumulation Q i This establishes a method for controlling second duration t2. The top row shows plots over intermediate values ​​of second duration t2, the middle row shows plots over shorter values ​​of second duration t2, and the bottom row shows plots over longer values ​​of second duration t2. It can be seen that changing the second duration t2 does not affect the amplitude of the substrate voltage, but does affect the length of time the substrate voltage is at a constant negative voltage (or a substantially constant or sustained negative voltage), and therefore affects the ion flux to the substrate. Thus, reducing the second duration t2 too much can lead to reduced production. Extending the second duration t2 can increase the total amount of time during which the plasma is working on the substrate, but can also lead to excessive charge accumulation. Thus, the duration of ion bombardment and surface charge accumulation Q i A balance between often needs to be found.

[0286] FIG. 66 illustrates a method for biasing a substrate and controlling (e.g., limiting) accumulated surface charge. Method 6600 can include applying an asymmetric periodic voltage function to an output (block 6602). A power supply can be configured to provide this voltage function. The output can be configured to couple to a substrate support. The asymmetric periodic voltage function can include a positive voltage ramp (e.g., 6160 in FIG. 61), a first negative voltage ramp (e.g., 6164) having a duration t1, and a second negative-positive ramp (e.g., 6166) having a second duration t2. This second negative voltage ramp can also be referred to as a linearly decreasing voltage. Method 6600 can include monitoring a slope dv / dt over duration t2 (block 6604). This can be used to measure ion current within the plasma processing chamber. In some embodiments, an ion current compensation component, such as 5836, can perform the monitoring of block 6604. The method 6600 then uses Equation 10 to calculate the ion current I I (block 6606), and then calculate the ion current I I and using equation 11, the surface charge accumulation Q i This calculation can be performed by an ion current compensation component such as 5836 or by a controller such as 5832. Surface charge accumulation Q i In parallel with, or prior to, the calculation of Q, the method 6600 can adjust the output of an ion compensation component (e.g., current or voltage), and a switch-mode power supply, such as 5830, can adjust the output voltage drop ΔV (e.g., 6164) to achieve a desired ion energy distribution (e.g., a controllable narrow or monoenergetic ion energy distribution) (block 6608). i Once Q is known, or at least estimated, it can be compared to a threshold or range (decision 6610). i If Q is below or within this threshold, the method 6600 returns to the monitoring step (block 6604) to determine if there is excessive or out-of-range surface charge accumulation Q iThis determination can be made by an ion current compensation component, such as 5836, or by a controller, such as 5832. If the determination 6610 is "yes," the method 6600 adjusts the duration t2 of the linearly decreasing voltage (block 6612) until the determination 6610 determines that the surface charge accumulation Q i The controller may return to monitoring dv / dt until it finds that dv / dt is back within bounds or below the threshold (block 6604). A controller such as 5832 may, in one case, control the second duration t2 of the linearly decreasing voltage via a signal to a switch in a switched mode power supply.

[0287] Figure 67 illustrates another method of biasing a substrate and controlling accumulated surface charge. Method 6700 can include biasing a substrate in a plasma processing chamber with a linearly decreasing voltage between pulses of an asymmetric periodic voltage function, such as those seen in Figures 61 and 62 (block 6702). A power supply can be configured to provide this voltage function. An output can be configured to couple to the substrate support. The linearly decreasing voltage can continue for a duration t2, which is a controllable value. The method then calculates the ion current I using Equation 10: I (block 6704), and then calculate the ion current I I and using equation 11, the surface charge accumulation Q i (block 6704). This calculation can be performed by an ion current compensation component, such as 5836, or by a controller, such as 5832. Surface charge accumulation Q during duration t i can then be compared to a threshold or range (decision 6706). i If (decision 6706) is below or within this threshold, the method 6600 determines whether the ion current I I and surface charge accumulation Q i (block 6704) to calculate the excessive or out-of-range surface charge accumulation Q iThis determination can be made by an ion current compensation component, such as 5836, or by a controller, such as 5832. If the determination 6706 is "yes," the method 6700 adjusts the duration t2 of the linearly decreasing voltage (block 6708) to adjust the ion current I I and surface charge accumulation Q i (block 6704) to calculate the excessive or out-of-range surface charge accumulation Q i A controller such as the 5832 can control the duration t2 of the linearly decreasing voltage, in one case via a signal to a switch in a switched mode power supply.

[0288] In some embodiments, the components and functions of the ionic current compensation component 5836 can be implemented within the switched mode power supply 5830.

[0289] Integration method for determining the slope of a modified periodic voltage function

[0290] In another embodiment, the surface charge accumulation Q i can be estimated without knowing the slope dv / dt of the linearly decreasing voltage during the second duration t2. Instead, the area under the voltage curve during the second duration t2 is used to estimate the surface charge accumulation Q i One method for determining this area is to use the ion current I for the second duration t as shown in Equation 12 below: I via the integral of

[0291]

number

[0292] Ion current I I For example, the ionic compensation current I C may be determined, as described above, by adjusting the ion current I Iis then the ionic compensation current I C (e.g., I C =I I ).

[0293] This disclosure provides a surface charge accumulation Q i Although it explains i Note that σ can refer to the delivered charge because there may be several sources of charge leakage. Similarly, Equations 11 and 12 can refer to the delivered charge rather than the charge accumulation.

[0294] The methods described in connection with the embodiments disclosed herein may be embodied directly in hardware, in processor-executable code encoded in a non-transitory tangible processor-readable storage medium, or in a combination of the two. Referring to FIG. 69, for example, shown is a block diagram depicting physical components that may be utilized to implement control aspects of plasma power supplies 102, 202, 1202, 1702, 2122, 2222, 2322, 2422, 2522, 2622, 2722 and bias supplies 106, 206, 806, 1206, 1366, 1806 and 1884, 1906, 2130, 2230, 2330, 2430, 2530, 2630, 2730, 5102, 5202, 5500, 5803, 5902, 6002, and 6502 in accordance with an exemplary embodiment. As shown, in this embodiment, the display portion 6912 and non-volatile memory 6920 are coupled to a bus 6922, which is also coupled to a random access memory ("RAM") 6924, a processing portion (including N processing components) 6926, a field programmable gate array (FPGA) 6927, and a transceiver component 6928, which includes N transceivers. While the components depicted in FIG. 69 represent physical components, FIG. 69 is not intended to be a detailed hardware diagram, and thus many of the components depicted in FIG. 69 may be realized by a common structure or distributed among additional physical components. Furthermore, it is contemplated that other existing and yet-to-be-developed physical components and architectures may be utilized to implement the functional components described with reference to FIG. 69.

[0295] The display portion 6912 generally operates to provide a user interface for a user, and in some implementations, the display is realized by a touch screen display. Generally, the non-volatile memory 6920 is a non-transitory memory that functions to store (e.g., persistently store) data and processor executable code (including executable code associated with effecting the methods described herein). In some embodiments, for example, the non-volatile memory 6920 includes boot loader code, operating system code, file system code, and non-transitory processor executable code, optionally facilitating execution of methods for biasing a substrate to achieve one or more IEDF energy peaks having different amplitudes, as described with reference to Figures 6, 9-11, 42B, 42C, 46, and 48-50. One or more of the monitoring circuitry 5770, the chamber analysis component 5772, and the control circuitry 5772 may be realized, at least in part, by non-transitory processor executable code.

[0296] In many implementations, non-volatile memory 6920 is realized by flash memory (e.g., NAND or ONENAND memory), although it is contemplated that other memory types may be utilized as well. While it may be possible to execute code from non-volatile memory 6920, executable code in non-volatile memory is typically loaded into RAM 6924 and executed by one or more of the N processing components in processing portion 6926.

[0297] The N processing components in communication with RAM 6924 generally operate to execute instructions stored in non-volatile memory 6920 to enable performance of the algorithms and functions disclosed herein. While several algorithms are disclosed herein, it should be appreciated that some of these algorithms are not represented in flowcharts. Processor-executable code for effecting the methods of biasing different localized regions of a substrate or chamber shown and described with respect to FIGS. 6, 9-11, 42B, 42C, 46, and 48-50 may be persistently stored in non-volatile memory 6920 and executed by the N processing components in communication with RAM 6924. As one skilled in the art would understand, processing portion 6926 may include a video processor, a digital signal processor (DSP), a microcontroller, a graphics processing unit (GPU), or other hardware processing component, or a combination of hardware and software processing components (e.g., an FPGA or FPGAs including digital logic processing portions).

[0298] Additionally or alternatively, the non-transient FPGA configuration instructions may be persistently stored in non-volatile memory 6920 and accessed (e.g., during boot-up) to configure the field programmable gate array (FPGA), implement the algorithms disclosed herein, and effect one or more of the functionality of the controller 5760 or other aspects of the RF sources 102, 202, 1202, 1702, 2122, 2222, 2322, 2422, 2522, 2622, 2722 and bias supplies 106, 206, 806, 1206, 1366, 1806 and 1884, 1906, 2130, 2230, 2330, 2430, 2530, 2630, 2730, 5102, 5202, 5500, 5803, 5902, 6002, and 6502.

[0299] The input component 6930 operates to receive a signal (e.g., current, voltage, and phase information at the output of the bias supply) indicative of one or more aspects of the modified periodic voltage function being supplied to the substrate support. The signal received at the input component may be, for example, V out or V out The output components generally operate to provide one or more analog or digital signals for effecting operational aspects for controlling the bias sources as disclosed herein and / or signals for effecting a desired IEDF. For example, the output section 6932 may provide control signals for controlling the switching of switches within the controllable current sources 2540, 2640, 2740, current sources 1664, or ion current compensation components 1260, 1360, 2136 and / or bias sources 106, 206, 806, 1206, 1366, 1806 and 1884, 1906, 2130, 2230, 2330, 2430, 2530, 2630, 2730, 5102, 5202, 5702.

[0300] The depicted transceiver component 6928 includes N transceiver chains, which may be used to communicate with external devices via wireless or wired networks. Each of the N transceiver chains may represent a transceiver associated with a particular communication scheme (e.g., WiFi, Ethernet, Profibus, etc.).

[0301] As will be appreciated by those skilled in the art, aspects of the present disclosure may be embodied as a system, method, or computer program product. Accordingly, aspects of the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, all generally referred to herein as a "circuit," "module," or "system." Furthermore, aspects of the present disclosure may take the form of a computer program product embodied in one or more computer-readable medium(s) having computer-readable program code embodied thereon.

[0302] In conclusion, the present disclosure provides, among other things, methods and apparatus for selectively generating a desired (or defined) ion energy using a switch-mode power supply. As used herein, the recitation of "at least one of A, B, or C" is intended to mean "any of A, B, C, or any combination of A, B, and C." The foregoing description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present disclosure. Those skilled in the art will readily recognize that numerous modifications and substitutions can be made to the invention, its use, and its configuration to achieve substantially the same results as those achieved by the embodiments described herein. Therefore, it is not intended that the invention be limited to the exemplary forms disclosed. Many modifications, variations, and alternative constructions are within the scope and spirit of the disclosed invention.

Claims

1. A system, comprising: a power supply for providing a waveform to an electrical node of a substrate support, the waveform comprising a plurality of pulses and negative portions between the plurality of pulses; at least one controller for controlling the power control source to adjust the duration of the negative portion between the plurality of pulses, thereby adjusting the surface charge accumulation on the substrate; A system comprising:

2. The power supply source a first power supply for providing the plurality of pulses; a second power supply for providing a current to modify the slope of the negative portion between the plurality of pulses; and The system of claim 1 , comprising:

3. The at least one controller adjusting the steps of the plurality of pulses to establish an initial substrate voltage; adjusting the magnitude of the current to control the derivation of a substrate voltage from the initial substrate voltage; The system of claim 2 , adapted to:

4. The system described in claim 2, wherein the first power supply comprises a DC power supply and at least one switch coupling the DC power supply to the electrical node, and in response to the at least one switch being closed, a peak voltage of the pulse is generated at the electrical node before the pulse drops by a voltage step.

5. The system described in claim 2, wherein the second power supply source is coupled to the electrical node via an inductor.

6. The system described in claim 2, wherein the at least one controller is adapted to calculate surface charge accumulation based on ion current impinging on the substrate.

7. The system described in claim 6, wherein the at least one controller is adapted to calculate the ion current based on at least one of the current or voltage of the waveform.

8. The at least one controller adjusts the surface charge accumulation Q i during the negative portion between the plurality of pulses. [Equation 23] 8. The system of claim 7, wherein Cchuck is a series capacitance between the substrate and the electrical node, and I I is the ion current.

9. A non-transitory, tangible, processor-readable storage medium encoded with processor-executable instructions, the instructions comprising: instructions to provide a waveform to a support, the waveform comprising a plurality of pulses and a negative portion between the plurality of pulses; instructions for calculating a surface charge accumulation on a substrate positioned on the support; instructions for adjusting the surface charge accumulation by adjusting the duration of the negative portion between the plurality of pulses; a non-transitory, tangible processor-readable storage medium, including:

10. The non-transitory, tangible, processor-readable storage medium comprising instructions for calculating ion current from measurements of the waveform; 10. The non-transitory, tangible, processor-readable storage medium of claim 9, wherein the instructions for calculating the surface charge accumulation comprise instructions for calculating the surface charge accumulation based on the calculated ion current.

11. A non-transitory, tangible, processor-readable storage medium as described in claim 10, wherein the instructions for calculating ion current from measurements of the waveform include instructions for calculating ion current from current measurements of the waveform during the negative portions between the multiple pulses.

12. A non-transitory, tangible, processor-readable storage medium as described in claim 10, wherein the instructions for calculating ion current from measurements of the waveform include instructions for calculating ion current from the rate of change of the negative portion between the multiple pulses.

13. The instructions for calculating the surface charge accumulation include: [0000] 11. The non-transitory, tangible processor-readable storage medium of claim 10, comprising instructions for calculating: where Cchuck comprises a series capacitance and I I is an ion current.

14. A non-transitory, tangible, processor-readable storage medium as described in claim 9, wherein the instructions include instructions for maintaining a constant duration of each of the plurality of pulses while adjusting the duration of the negative portion between the plurality of pulses.

15. A method, comprising: providing a waveform to a support, the waveform comprising a plurality of pulses and a negative portion between the plurality of pulses; calculating a surface charge accumulation on a substrate on said support; adjusting the surface charge accumulation by adjusting the duration of the negative portion between the plurality of pulses; A method comprising:

16. The method includes calculating an ion current from measurements of the waveform; The method of claim 15 , wherein calculating the surface charge accumulation comprises calculating the surface charge accumulation based on the calculated ion current.

17. The method of claim 16, wherein calculating the ion current from measurements of the waveform includes calculating the ion current from current measurements of the waveform during the negative portions between the multiple pulses.

18. The method described in claim 16, wherein calculating the ion current from measurements of the waveform includes calculating the ion current from the rate of change of the negative portion between the multiple pulses.

19. The method of claim 18, wherein the calculating step calculates the surface charge accumulation by: [Equation 25] 17. The method of claim 16, comprising calculating I I as: where C chuck comprises series capacitance and I I is ionic current.

20. The method of claim 15, wherein the method includes maintaining a constant duration for each of the plurality of pulses while adjusting the duration of the negative portion between the plurality of pulses.

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