Bias supply with a single controlled switch

Abstract

To provide a bias supply device with a single control type switch.SOLUTION: Bias supplies, plasma processing systems, and methods associated therewith are disclosed. One bias supply comprises a first inductor coupled between the first node of the switch and an output node, wherein a first node of a second inductor is coupled to one of the output node or the first node of the switch. A voltage source is coupled between a second node of the switch and a second node of the second inductor. A connection is made between the return node and one of the second node of the switch and the second node of the second inductor. The bias supply also includes a controller configured to cause application of a periodic voltage between the output node and the return node by repeatedly closing the switch such that a current through the switch completes a full cycle.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] (Claim of priority under 35 U.S.C. § 119) This patent application claims priority to Provisional Application No. 62 / 873,680, entitled "A SINGLE CONTROLLED SWITCH, SINGLE SUPPLY EV SOURCE WITH ION CURRENT COMPENSATION," filed July 12, 2019, which is assigned to the assignee hereof and expressly incorporated by reference herein.

[0002] (background) (Field) The present invention relates generally to power supply devices, and more particularly to power supply devices for applying voltages for plasma processing. [Background technology]

[0003] (background) Many types of semiconductors are made using plasma-based etching techniques. When the item being etched is a conductor, a voltage that is negative with respect to ground can be applied to the conductive substrate to create a substantially uniform negative voltage across the surface of the substrate conductor, which attracts positively charged ions to the conductor, resulting in positive ions that strike the conductor having substantially the same energy.

[0004] However, if the substrate is a dielectric, a static voltage is ineffective at imposing a voltage across the surface of the substrate. However, an alternating current (AC) voltage (e.g., high-frequency AC or radio frequency (RF)) can be applied to a conductive plate (or chuck) such that the AC field induces a voltage on the surface of the substrate. During the positive peak of the AC cycle, the substrate attracts electrons, which are lighter than the mass of positive ions, and therefore many electrons are attracted to the surface of the substrate during the positive peak of the cycle. As a result, the surface of the substrate becomes negatively charged, causing ions to be attracted to the negatively charged surface for the remainder of the AC cycle. Then, when the ions collide with the surface of the substrate, the collisions remove material from the surface of the substrate, achieving etching.

[0005] In many instances, it is desirable to have a narrow ion energy distribution, but applying a sinusoidal waveform to a substrate induces a wide distribution of ion energy, limiting the ability of the plasma process to achieve a desired etch profile. Known techniques for achieving a narrow ion energy distribution are costly, inefficient, difficult to control, and can adversely affect plasma density. As a result, these known techniques have not been commercially adopted. Therefore, there is a need for systems and methods that address the shortcomings of current technology and provide other new and innovative features. Summary of the Invention [Means for solving the problem]

[0006] (overview) Certain aspects of some implementations disclosed herein address the above-mentioned needs by utilizing a switching frequency along with a single controlled switch in a resonant circuit that requires only one variable voltage supply as a means of control, allowing a dramatically simplified circuit to provide the desired narrow energy distribution.

[0007] Another aspect can be characterized as a power supply device including an output node, a return node, a switch, a first inductor, a second inductor, and a voltage source. The first inductor is coupled between a first node of the switch and the output node, and a first node of the second inductor is coupled to one of the output node or the first node of the switch. The voltage source is coupled between a second node of the switch and a second node of the second inductor, and a connection is made between the return node and one of the second node of the switch and the second node of the second inductor. The controller is configured to cause application of a periodic voltage between the output node and the return node by repeatedly closing the switch long enough for a current through the switch to complete a full cycle (going from zero to a peak value, returning to zero, going to the peak value in the opposite direction, and returning to zero).

[0008] Yet another aspect can be characterized as a power supply including an output node, a return node, a switch, a transformer, and a voltage source. A first node of a primary winding of the transformer is coupled to a first node of the switch, a first node of a secondary winding of the transformer is coupled to the output node, and a second node of the secondary winding of the transformer is coupled to the return node. The voltage source is coupled between a second node of the switch and a second node of the primary winding of the transformer. The power supply also includes a controller configured to cause application of a periodic voltage between the output node and the return node by repeatedly closing the switch long enough for a current through the switch to complete a full cycle (going from zero to a peak value, returning to zero, going to the peak value in the opposite direction, and returning to zero).

[0009] Another aspect disclosed herein is a plasma processing system including a plasma chamber and a bias supply. The plasma chamber includes a volume for containing a plasma, an input node, and a return node. The bias supply includes a switch, a first inductor, a second inductor, and a voltage source. The first inductor is coupled between a first node of the switch and an input node of the plasma chamber, and a first node of the second inductor is coupled to one of the input node of the chamber or the first node of the switch. The voltage source is coupled between a second node of the switch and a second node of the second inductor. A connection is made between the return node and one of the second node of the switch or the second node of the second inductor. The plasma processing system also includes means for controlling the switch and the voltage source to achieve a desired waveform of a voltage of a plasma load when a plasma is present in the plasma chamber.

[0010] Yet another aspect can be characterized as a plasma processing system including a plasma chamber and a bias supply. The plasma processing chamber includes a volume for containing a plasma, an input node, and a return node, and the bias supply includes a switch, a transformer, and a voltage source. A first node of a primary winding of the transformer is coupled to a first node of the switch, a first node of a secondary winding of the transformer is coupled to an input node of the plasma chamber, and a second node of the secondary winding of the transformer is coupled to the return node. The voltage source is coupled between the second node of the switch and the second node of the primary winding of the transformer. The plasma processing system also includes means for controlling the switch and the voltage source to achieve a desired waveform of a voltage of the plasma load when a plasma is present in the plasma chamber. The present invention provides, for example, the following. (Item 1) A bias supply device for applying a periodic voltage, the bias supply device comprising: an output node; A return node; Switch and a first inductor coupled between a first node of the switch and the output node; a first node of a second inductor coupled to one of the output node or the first node of the switch; a voltage source coupled between a second node of the switch and a second node of the second inductor; a connection between the return node and one of the second node of the switch and the second node of the second inductor; Control device and Equipped with The control device is configured to cause the application of the periodic voltage between the output node and the return node by repeatedly closing the switch long enough to cause current through the switch to complete a full cycle, the full cycle going from zero to a peak value, back to zero, back to the peak value in the opposite direction, and back to zero. (Item 2) 2. The bias supply apparatus of claim 1, wherein the control device is configured to adjust the voltage of the voltage source and the time between the repeated switch closures to achieve a desired periodic voltage. (Item 3) 2. The bias supply apparatus of claim 1, wherein the control device includes at least one of a processor or a field programmable gate array, and the control device includes a non-transitory computer-readable medium having instructions stored thereon for execution by the processor or for configuring the field programmable gate array to control operation of the switch. (Item 4) A bias supply device for applying a periodic voltage, the bias supply device comprising: an output node; A return node; Switch and a transformer, wherein a first node of a primary winding of the transformer is coupled to a first node of the switch, a first node of a secondary winding of the transformer is coupled to the output node, and a second node of the secondary winding of the transformer is coupled to the return node; a voltage source coupled between a second node of the switch and a second node of the primary winding of the transformer; Control device and Equipped with The control device is configured to cause the application of the periodic voltage between the output node and the return node by repeatedly closing the switch long enough to cause current through the switch to complete a full cycle, the full cycle going from zero to a peak value, back to zero, back to the peak value in the opposite direction, and back to zero. (Item 5) 5. The bias supply apparatus of claim 4, wherein the second node of the switch is coupled to the return node. (Item 6) 5. The bias supply apparatus of claim 4, wherein the second node of the primary winding of the transformer is coupled to the return node. (Item 7) 5. The bias supply apparatus of claim 4, wherein the control device includes at least one of a processor or a field programmable gate array, and the control device includes a non-transitory computer-readable medium having instructions stored thereon for execution by the processor or for configuring the field programmable gate array to control operation of the switch. (Item 8) 1. A plasma processing system, comprising: A plasma chamber, the plasma chamber comprising: a volume for containing the plasma; an input node; Return node and a plasma chamber including: A bias supply device, the bias supply device comprising: Switch and a first inductor coupled between a first node of the switch and the input node of the plasma chamber; a bias supply device including: a first node of a second inductor coupled to one of the input node of the chamber or the first node of the switch; a voltage source coupled between a second node of the switch and a second node of the second inductor; a connection between the return node and one of the second node of the switch or the second node of the second inductor; means for controlling the switch and the voltage source to achieve a desired waveform of the voltage across the plasma load when the plasma is in the plasma chamber; A plasma processing system comprising: (Item 9) 9. The plasma processing system of claim 8, wherein the means for controlling includes means for adjusting the voltage of the voltage source and the time between repeated switch closures to achieve the desired waveform of the voltage of the plasma load. (Item 10) 9. The plasma processing system of claim 8, wherein the means for controlling includes means for closing the switch long enough for current through the switch to complete a full cycle, going from zero to a peak value, back to zero, back to the peak value in the opposite direction, and back to zero, for each closure of the switch. (Item 11) Item 10. The plasma processing system of item 8, wherein the return node comprises a ground return. (Item 12) 1. A plasma processing system, comprising: A plasma chamber, the plasma chamber comprising: a volume for containing the plasma; an input node; Return node and a plasma chamber including: A bias supply device, the bias supply device comprising: Switch and a converter, wherein a first node of a primary winding of the converter is coupled to a first node of the switch, a first node of a secondary winding of the converter is coupled to the input node of the plasma chamber, and a second node of the secondary winding of the converter is coupled to the return node; a voltage source coupled between a second node of the switch and a second node of the primary winding of the transformer; a bias supply device including: means for controlling the switch and the voltage source to achieve a desired waveform of the voltage across the plasma load when the plasma is in the plasma chamber; A plasma processing system comprising: (Item 13) 13. The plasma processing system of claim 12, wherein the means for controlling includes means for adjusting the voltage of the voltage source and the time between repeated switch closures to achieve the desired waveform of the voltage of the plasma load. (Item 14) Item 13. The plasma processing system of item 12, wherein the means for controlling includes means for closing the switch long enough for current through the switch to complete a full cycle, going from zero to a peak value, back to zero, back to the peak value in the opposite direction, and back to zero, for each closure of the switch. (Item 15) Item 13. The plasma processing system of item 12, wherein the second node of the switch is coupled to the return node. (Item 16) Item 13. The plasma processing system of item 12, wherein the second node of the primary winding of the transformer is coupled to the return node. (Item 17) Item 13. The plasma processing system of item 12, wherein the return node comprises a ground return. [Brief explanation of the drawings]

[0011] BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1] FIG. 1 is a block diagram depicting an exemplary plasma processing environment in which the bias supply apparatus disclosed herein may be utilized.

[0012] [Figure 2] FIG. 2 is a circuit diagram depicting an exemplary bias supply.

[0013] [Figure 3] FIG. 3 is a circuit diagram illustrating an electrical representation of an embodiment of a plasma processing chamber.

[0014] [Figure 4] FIG. 4 is a timing diagram depicting the timing of the electrical aspects of the bias supply apparatus of FIG. 2 when operated in conjunction with the plasma processing chamber of FIG.

[0015] [Figure 5A] FIG. 5A is a graphical depiction of sheath voltage versus time and the resulting ion flux versus ion energy.

[0016] [Figure 5B] FIG. 5B is a graph of a periodic voltage waveform that may produce the sheath voltage depicted in FIG. 5A.

[0017] [Figure 6A] FIG. 6A depicts different sheath voltages and the resulting ion flux versus ion energy.

[0018] [Figure 6B] FIG. 6B is a graph of a periodic voltage waveform that may produce the sheath voltage depicted in FIG. 6A.

[0019] [Figure 7A]FIG. 7A depicts yet another sheath voltage and the resulting ion flux versus ion energy.

[0020] [Figure 7B] FIG. 7B is a graph of a periodic voltage waveform that may produce the sheath voltage depicted in FIG. 7A.

[0021] [Figure 8] FIG. 8 includes graphs depicting periodic voltage waveforms and corresponding sheath voltages that may be applied by the bias supply of FIG.

[0022] [Figure 9] FIG. 9 includes graphs depicting alternative periodic voltage waveforms and corresponding sheath voltages that may be applied by the bias supply of FIG.

[0023] [Figure 10] FIG. 10 includes graphs depicting alternative periodic voltage waveforms and corresponding sheath voltages that may be applied by the bias supply of FIG.

[0024] [Figure 11] FIG. 11 is a circuit diagram depicting another exemplary bias supply apparatus.

[0025] [Figure 12] FIG. 12 includes graphs depicting periodic voltage waveforms and corresponding sheath voltages that may be applied by the bias supply of FIG.

[0026] [Figure 13] FIG. 13 includes graphs depicting alternative periodic voltage waveforms and corresponding sheath voltages that may be applied by the bias supply of FIG.

[0027] [Figure 14]FIG. 14 includes graphs depicting yet another periodic voltage waveform and corresponding sheath voltage that may be applied by the bias supply of FIG.

[0028] [Figure 15A] FIG. 15A is a flowchart depicting a method that may be discussed in connection with some embodiments.

[0029] [Figure 15B] FIG. 15B is a flowchart depicting another method that may be discussed in connection with some embodiments.

[0030] [Figure 16A] FIG. 16A is a circuit diagram depicting an exemplary bias supply.

[0031] [Figure 16B] FIG. 16B is a circuit diagram depicting another exemplary bias supply apparatus.

[0032] [Figure 16C] FIG. 16C is a circuit diagram depicting another exemplary bias supply apparatus.

[0033] [Figure 16D] FIG. 16D is a circuit diagram depicting another exemplary bias supply.

[0034] [Figure 16E] FIG. 16E is a circuit diagram depicting another exemplary bias supply.

[0035] [Figure 16F] FIG. 16F is a circuit diagram depicting another exemplary bias supply.

[0036] [Figure 17] FIG. 17 is a block diagram depicting components that may be utilized to implement the controls disclosed herein. DETAILED DESCRIPTION OF THE INVENTION

[0037] (Detailed explanation) The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0038] As a preliminary remark, the flowcharts and block diagrams in the following figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and program products according to various embodiments. In this regard, some blocks in these flowcharts or block diagrams may represent modules, segments, or portions of code comprising one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may in fact be executed substantially simultaneously, or the blocks may sometimes be executed in the reverse order, depending on the functionality involved. It should also be noted that each block of the block diagrams and / or flowchart diagrams, and combinations of blocks in the block diagrams and / or flowchart diagrams, may be implemented by a dedicated hardware-based system that performs the specified functions or acts, or a combination of dedicated hardware and computer instructions.

[0039] For purposes of this disclosure, a source generator is one whose energy is primarily directed to generating and sustaining a plasma, while a "bias supply" is one whose energy is primarily directed to generating a surface potential to attract ions and electrons from the plasma.

[0040] Described herein are several embodiments of a novel bias supply apparatus that can be used to apply a periodic voltage function to a substrate support in a plasma processing chamber.

[0041] Referring first to FIG. 1 , an exemplary plasma processing environment (e.g., a deposition or etching system) in which a bias supply may be utilized is shown. The plasma processing environment may include a number of components coupled directly and indirectly to a plasma chamber 101, which contains a volume containing a plasma 102 and a workpiece 103 (e.g., a wafer). The components may include vacuum handling and gas delivery equipment (not shown), one or more bias supplies 108, one or more source generators 112, and one or more source matching networks 113. In many applications, power from a single source generator 112 is connected to one or more source electrodes 105. The source generator 112 may be a relatively high-frequency RF generator (e.g., 13.56 MHz to 120 MHz). Generally, electrode 105 represents an inductively coupled plasma (ICP) source, a dual capacitively coupled plasma source (CCP) with a secondary upper electrode biased at another RF frequency, a helicon plasma source, a microwave plasma source, a magnetron, or any other independently operated source of plasma energy.

[0042] 1, the source generator 112 and source matching network 113 may be replaced or augmented with a remote plasma source. Other variations of the system may include only a single bias supply 108.

[0043] While the following disclosure generally refers to plasma-based wafer processing, implementations can include any substrate processing in a plasma chamber. In some examples, objects other than substrates can be processed using the systems, methods, and apparatus disclosed herein. In other words, the present disclosure is directed to plasma processing of any object in a sub-atmospheric pressure plasma processing chamber to affect surface modification, sub-surface modification, deposition, or removal by physical or chemical means.

[0044] 2, an exemplary bias supply 208 for applying a periodic voltage function is shown. As shown, the bias supply 208 includes an output 210 (also referred to as an output node 210), a switch 220, and a voltage source 230. Additionally, a first inductor 240 is coupled between the switch and the output, and a second inductor 250 is coupled between the voltage source and the output. A controller 260 is also shown and is configured to open and close the switch 220 to generate a voltage at the output, as described further herein. For example, the controller 260 can be configured to cause application of a periodic voltage between the output 210 (also referred to as an output node 210) and a ground connection 270 (also referred to as a return node 270) by repeatedly closing the switch long enough for the current through the switch to complete a full cycle (going from zero to a peak value, returning to zero, going to the peak value in the opposite direction, and returning to zero). The current delivered to the load through output 210 is returned to bias supply 208 through a ground connection 270 common to the load.

[0045] Referring briefly to Figure 3, a schematic diagram is shown that electrically depicts aspects of the plasma load within the plasma chamber 101. As shown, the plasma chamber 101 has a chuck capacitance C ch (including the capacitance of the chuck and workpiece 103), and the plasma chamber 101 is represented by an input 310 (also referred to as input node 310) to the plasma chamber 101 and a voltage V at the surface of the substrate.S (also referred to herein as sheath voltage). In addition, a return node 307 (which may be a connection to ground) is depicted. The plasma 102 in the processing chamber is connected to a sheath capacitance C S The workpiece 103 is represented by a parallel combination of a diode and a current source. The diode represents the nonlinear, diode-like behavior of the plasma sheath, which results in rectification of the applied AC electric field, causing a direct current (DC) voltage drop to appear between the workpiece 103 and the plasma 102.

[0046] Referring again to FIG. 2 , switch 220 includes a body diode (like many field-effect switches), which allows reverse current even when the switch is not controlled to be in an on state. Applicant has discovered that a body diode can be used to advantage because switch 220 can be turned off at any time during the first reversal of current through the switch (thus reducing the timing criticality of control). While other types of switches can be used, the switch can be embodied by a silicon carbide metal oxide semiconductor field-effect transistor (SiC MOSFET). It should be recognized that the drive signal 211 from the control device can be electrical or optical. It should also be understood that the switches depicted in the other bias supply devices disclosed herein (e.g., in FIGS. 11 and 16A-16F) can also include body diodes, and that the switches of the other bias supply devices can be driven by the drive signal 211.

[0047] Referring to Figure 4, the ion current I イオン 1. Waveforms depicting the electrical behavior of the bias supply 208 and plasma processing chamber 101 when is properly compensated are shown, which indicates that the current i through the second inductor L2 L2 is the ion current I イオン This occurs when the current i through L2 is equal to L2 is the ion current Iイオン 4, switch 220 (also referred to herein as switch S) can be controlled so that the current through first inductor 240 (and thus through switch 220) completes a full cycle (going from zero to a peak value, back to zero, back to the peak value in the opposite direction, and back to zero). L2 The peak value of the current i L2 It should be appreciated that the peak value of V may differ from the peak value of V. Controller 260 adjusts the voltage of voltage source 230 and the time between repeated switch closures to O It may also be configured to achieve a desired periodic voltage at

[0048] 5A-7B, background information useful for understanding the effect of ion current compensation on the distribution of ion energy within the plasma chamber 101 is depicted. First, I L2 =I イオン Reference is now made to Figures 5A and 5B in a mode of operation in which the sheath voltage is substantially constant between pulses. As shown in Figure 5A, when the sheath voltage is substantially constant between pulses, the corresponding ion energy dispersion 570 is relatively narrow to produce a substantially monoenergetic ion energy distribution function. An asymmetric periodic voltage function that may be applied by the bias supply 108 to produce the sheath voltage in Figure 5A is shown in Figure 5B.

[0049] 6A and 6B, aspects of the sheath voltage, ion flux, and asymmetric periodic voltage waveform (output by the bias supply) associated with undercompensated ion current are shown. As shown in FIG. 6A, the ion current I イオンWhen is under-guaranteed, the sheath voltage becomes less negative in its ramping behavior, producing a wider distribution of ion energies 672. A periodic voltage that may be applied to the substrate support to achieve the sheath voltage depicted in FIG. 6A is shown in FIG. 6B. As shown, the negative ramping portion of the periodic voltage waveform drops off with a lower slope than the ramping portion of the periodic voltage waveform of FIG. 5B (shown as a dashed line in FIG. 6B). Note that such a distribution of ion energies 672 may be intentional.

[0050] 7A and 7B depict aspects of the sheath voltage, ion flux, and asymmetric periodic voltage waveform (output by the bias supply) associated with overcompensated ion current. As shown in FIG. 7A, when the ion current is overcompensated, the sheath voltage becomes more negative in its ramp behavior, also producing a wider distribution 774 of ion energies. A periodic voltage waveform that may be applied to the substrate support to achieve the sheath voltage depicted in FIG. 7A is shown in FIG. 7B. As shown, the negative ramp portion of the periodic voltage function drops off at a greater rate than the ramp portion of a periodic voltage waveform that compensates for the ion current (shown as a dotted line). Such a distribution 774 of ion energies may be intentional and may be desired.

[0051] Referring back to FIGS. 2, 3 and 4, Applicant has determined that the bias supply output V O By controlling the pulse repetition rate of the periodic voltage applied at L2 (and therefore the compensation current) can be controlled. The pulse repetition rate can then be controlled by timing the opening and closing of the switches. Applicant has examined what happens if the time to the next on after one switch on is modified. For example, Applicant has found that the second on of switch S occurs slightly earlier, so that V O is a constant, the applied voltage V OIn this case, the second turn-on starts with the same initial conditions, so the shape of the second voltage pulse for the applied voltage V0 should be the same. Now, the time between pulses is shorter and the applied voltage V O is higher, so the current through L2 should increase. L2 The increase in the applied voltage V O Increasing the downward slope of the second pulse further increases the magnitude of the second pulse. Therefore, increasing the pulse repetition rate is a key to increasing ion current compensation. This has been confirmed through simulations, as shown in Figures 8-10.

[0052] Referring to FIG. 8, it shows the bias supply output voltage V for the circuit of FIG. 2 connected to a load as shown in FIG. O and sheath voltage V S In Figure 8, the voltage source is 230V. b provides a DC voltage of 5 kV, V at 300 kHz O When the switch is opened and closed to provide a pulse repetition rate of L1 = 3 μH, L2 = 4 mH, C ch =1.5nF, C S = 1nF, and I イオン = 3 A. Operating the circuit with these parameters results in an initial sheath voltage V of -5 kV, since the ion current is undercompensated. S As shown in Figure 2, the repetition rate of the switch closures is O and closing the switch will cause a current I L1 may be performed for a time long enough to complete a full cycle (going from zero to the peak value, back to zero, going to the peak value in the opposite direction, and back to zero). O During the cycle of the periodic voltage at L2 It should also be appreciated that may be substantially constant.

[0053] Referring now to Figure 9, the output voltage V of the bias supplyO and sheath voltage V S A graph depicting this is shown, which is a voltage source of 230V. b with the same parameters as in Figure 8, except that the switch is opened and closed to provide a DC voltage of 4.5 kV and a pulse repetition rate of 650 kHz. Operating the bias supply with these parameters results in a constant sheath voltage of -5 kV, since the ion current is accurately compensated.

[0054] Referring to FIG. 10, the output voltage V of the bias supply O and sheath voltage V S A graph depicting the voltage source V b provides a DC voltage equal to 4.25 kV, V with a pulse repetition rate of 800 kHz. O With the same parameters as in Figure 8, except the switch is opened and closed to provide . Operating the circuit with these parameters results in an initial sheath voltage of -5 kV being reduced to -5.25 kV because the ion current is overcompensated.

[0055] 11, a schematic diagram of a bias supply circuit including a transformer 1160 that couples a periodic voltage function to an output 1110 (also referred to as an output node 1110) is shown. As shown, the bias supply includes a voltage source 1130 and an inductor 1140 coupled to a switch 1120 and the transformer 1160. A controller 1150 is coupled to the switch, and the controller is configured to open and close the switch to generate an asymmetric voltage at the output. The inductor 1140 may be a separate inductor or may be part of the leakage inductance of the transformer 1160. For simulation purposes, the transformer is modeled as two fully coupled inductors. The parasitic capacitance between the windings of the transformer is C W It is modeled by

[0056] FIG. 12 shows the bias supply output voltage V for the circuit of FIG. 11 connected to a load as shown in FIG. Oand sheath voltage V S 12 is a graph depicting the results when the voltage source of the bias supply of FIG. 11 applies 422 VDC and the control device opens and closes the switch to generate a periodic voltage with a pulse repetition rate of 300 kHz at the output, with L1=50 nH, Lp=56 μH, and L S =5.6mH, C W =1.26nF, C ch =1.5nF, C S = 1nF, and I イオン =3 A. Operating the bias supply with these parameters results in an initial sheath voltage of -5 kV increasing to -2.8 kV because the ion current is undercompensated.

[0057] Figure 13 shows the output voltage V of the bias supply. O and sheath voltage V S 11 with the same parameters as FIG. 12, except that the voltage source of the bias supply of FIG. 11 applies 281 VDC and the controller opens and closes the switch to generate a periodic voltage with a pulse repetition rate of 775 kHz at the output. Operating the circuit with these parameters results in a constant sheath voltage of −5 kV, since the ion current is accurately compensated.

[0058] Figure 14 shows the output voltage V of the bias supply. O and sheath voltage V S 12 with the same parameters as FIG. 12, except that the voltage source of the bias supply of FIG. 11 applies 212 VDC and the controller opens and closes the switch to produce a periodic voltage with a 1 MHz pulse repetition rate at the output. Operating the circuit with these parameters results in an initial sheath voltage of −5 kV decreasing to −5.24 kV because the ion current is overcompensated.

[0059] Referring now to FIG. 15A, a flowchart is shown depicting a method that may be further discussed in connection with embodiments disclosed herein (e.g., in connection with FIGS. 16A-16D). As shown, a first node of a first inductor (also referred to herein as a small inductive element) is connected to a first node of a switch, a second node of the small inductive element is connected to an output node, and a capacitively coupled plasma load is connected between the output node and a return node (block 1510). A first node of the first inductor (also referred to as a large inductive element) may be connected to either node of the small inductive element (block 1520). As shown, a voltage source is connected between a second node of the switch and a second node of the large inductive element, and either node of the voltage source is connected to the return node (block 1530). In operation, the switch is repeatedly closed long enough for current through the switch to complete a full cycle (going from zero to a peak value, returning to zero, going to a peak value in the opposite direction, and returning to zero) (block 1540). Additionally, the voltage of the voltage source and the time between repeated switch closures can each be adjusted to achieve a desired waveform of the voltage of the plasma load (block 1550). For example, the desired waveform can be a sheath voltage that achieves a narrow distribution of ion energies (e.g., as shown in FIG. 5A) or a wider distribution of ion energies (e.g., as shown in FIGS. 6A and 7A).

[0060] FIG. 15B is another flowchart depicting a method that may be discussed in detail with respect to embodiments disclosed herein (e.g., with respect to FIGS. 16E and 16F ). As shown, a first node of a primary winding of a transformer is connected to a first node of a switch, a first node of a secondary winding of the transformer is connected to an output node, and a capacitively coupled plasma load is connected between the output node and a second node of the secondary of the transformer (block 1511). In addition, a voltage source is connected between a second node of the switch and a second node of the primary winding of the transformer (block 1521). In operation, the switch is closed long enough for current through the switch to complete a full cycle (going from zero to a peak value, returning to zero, going to a peak value in the opposite direction, and returning to zero) (block 1531). Additionally, the voltage of the voltage source and the time between repeated switch closures may each be adjusted to achieve a desired waveform of the voltage of the plasma load (block 1541). For example, as discussed above, a desired waveform may be a sheath voltage that achieves a narrow distribution of ion energies (e.g., as shown in FIG. 5A) or a wider distribution of ion energies (e.g., as shown in FIGS. 6A and 7A).

[0061] 16A, an exemplary bias supply 1601 for applying a periodic voltage function to a capacitively coupled plasma load 1602 (such as that present in a plasma chamber, e.g., plasma chamber 101) is shown. An output node 1604 of the bias supply 1601 connects to an input node 1605 of the plasma load 1602, and a return node 1606 of the bias supply 1601 connects to a return node 1607 of the plasma chamber 101. The return nodes 1606 and 1607 are often connected through the chassis or enclosure of both the bias supply and the plasma load, which are typically held at ground potential and are therefore also typically referred to as ground, chassis ground, or earth ground. As shown, the bias supply 1601 utilizes a DC supply 1603 as a voltage source, with the positive output terminal of the DC supply connected to ground and a large inductor L2 connected to the load side of a small inductor L1.

[0062] As shown, a first inductor L1 is coupled between a first node 1670 of switch S and the output node 1604, and a first node 1672 of a second inductor L2 is coupled to the output node 1604. A voltage source is coupled between a second node 1674 of switch S and a second node 1676 of second inductor L2, and a connection is made between the return node 1606 and the second node 1674 of switch S.

[0063] 16B, an exemplary bias supply 1611 for applying a periodic voltage function to a capacitively coupled plasma load 1612 is shown. As shown, the bias supply 1611 utilizes a DC supply 1613, with the negative output terminal of the DC supply 1613 connected to ground and a large inductor L2 connected to the load side of the small inductor L1. As shown, a first inductor L1 is coupled between a first node 1670 of a switch S and the output node 1604, and a first node 1672 of a second inductor L2 is coupled to the output node 1604. A voltage source is coupled between a second node 1674 of the switch S and a second node 1676 of the second inductor L2, and a connection is made between the return node 1606 and the second node 1676 of the second inductor L2.

[0064] 16C, an exemplary bias supply 1621 for applying a periodic voltage function to a capacitively coupled plasma load 1622 is shown. As shown, the bias supply 1621 utilizes a DC supply 1623, with the positive output terminal of the DC supply 1623 connected to ground and a large inductor L2 connected to the switch side of a small inductor L1. As shown, a first inductor L1 is coupled between a first node 1670 of a switch S and the output node 1604, and a first node 1672 of a second inductor L2 is coupled to the first node 1670 of the switch S. A voltage source is coupled between a second node 1674 of the switch S and a second node 1676 of the second inductor L2, and a connection is made between the return node 1606 and the second node 1674 of the switch S.

[0065] Referring to FIG. 16D, an exemplary bias supply 1631 for applying a periodic voltage function to a capacitively coupled plasma load 1632 is shown. As shown, the bias supply 1631 utilizes a DC supply 1633, with the negative output terminal of the DC supply 1633 connected to ground and a large inductor L2 connected to the switch side of a small inductor L1. As shown, a first inductor L1 is coupled between a first node 1670 of a switch S and the output node 1604, and a first node 1672 of a second inductor L2 is coupled to the first node 1670 of the switch S. A voltage source is coupled between a second node 1674 of the switch S and a second node 1676 of the second inductor L2. As shown, a connection is made between the return node 1606 and the second node 1676 of the second inductor L2.

[0066] Referring to FIG. 16E, an exemplary bias supply 1641 is shown for applying a periodic voltage function to a capacitively coupled plasma load 1642. As shown, the bias supply 1641 utilizes a DC supply 1643 (as a voltage source), with the positive output terminal of the DC supply 1643 connected to ground, and a transformer 1644 is used to connect to the plasma load 1642. The transformer has a primary winding (L LP and L P ) and the secondary winding (L S and L LS A first node 1680 of the primary winding of the transformer is coupled to a first node 1670 of the switch S. A first node 1682 of the secondary winding of the transformer is coupled to the output node 1604. And a second node 1684 of the secondary winding of the transformer is coupled to the return node 1606. A DC supply 1643 (voltage source) is coupled between a second node 1674 of the switch S and a second node 1686 of the primary winding of the transformer.

[0067] Referring to FIG. 16F, an exemplary bias supply 1651 for applying a periodic voltage function to a capacitively coupled plasma load 1652 is shown. As shown, the bias supply 1651 utilizes a DC supply 1653 as a voltage source, with the negative output terminal of the DC supply 1653 connected to ground, and a transformer 1654 is used to connect to the load. The bias supplies 1641, 1651 in both FIG. 16E and FIG. 16F include a transformer. And, as shown, a first node of a primary winding of the transformer is coupled to a first node of a switch, a first node of a secondary winding of the transformer is coupled to an output node, and a second node of the secondary winding of the transformer is coupled to a return node. The transformer has a primary winding (L LP and L P ) and the secondary winding (L S and L LS 16A and 16B, a first node 1680 of the primary winding of the transformer is coupled to a first node 1670 of the switch S. A first node 1682 of the secondary winding of the transformer is coupled to the output node 1604. And a second node 1684 of the secondary winding of the transformer is coupled to a return node 1606. A DC supply 1643 (voltage source) is coupled between a second node 1674 of the switch S and a second node 1686 of the primary winding of the transformer. As shown, the second node 1686 of the primary winding of the transformer is configured to couple to the return node 1607.

[0068] The methods described with respect to 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. For example, referring to FIG. 17, a block diagram depicting physical components that may be utilized to embody the control aspects disclosed herein is shown. As shown, in this embodiment, a display 1312 and non-volatile memory 1320 are coupled to a bus 1322, which is also coupled to a random access memory (“RAM”) 1324, a processing portion 1326 (including N processing components), a field programmable gate array (FPGA) 1327, and a transceiver component 1328 including N transceivers. While the components depicted in FIG. 17 represent physical components, FIG. 17 is not intended to be a detailed hardware diagram, and thus many of the components depicted in FIG. 17 may be embodied by a common construct 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.

[0069] Generally, the display 1312 operates to provide a user interface to a user, and in some implementations, the display is embodied by a touchscreen display. Generally, the non-volatile memory 1320 is non-transitory memory that functions to store (e.g., persistently store) data and machine-executable code (including executable code associated with implementing the methods described herein). For example, in some embodiments, the non-volatile memory 1320 includes boot loader code, operating system code, file system code, and non-transitory processor-executable code to facilitate execution of a method for biasing a substrate with a single controlled switch.

[0070] In many implementations, non-volatile memory 1320 is embodied 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 1320, executable code in non-volatile memory is typically loaded into RAM 1324 and executed by one or more of the N processing components in processing portion 1326.

[0071] Generally, the N processing components associated with RAM 1324 operate to execute instructions stored in non-volatile memory 1320, enabling performance of the algorithms and functions disclosed herein. It should be appreciated that while several algorithms are disclosed herein, some of these algorithms are not represented in the flowcharts. Processor-executable code for implementing the methods described herein may be persistently stored in non-volatile memory 1320 and executed by the N processing components associated with RAM 1324. As one skilled in the art will appreciate, processing portion 1326 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 an FPGA including a digital logic processing portion).

[0072] Additionally or alternatively, non-transitory FPGA configuration instructions may be persistently stored in non-volatile memory 1320 and accessed (e.g., during power-up) to configure a field programmable gate array (FPGA) to implement the algorithms disclosed herein (e.g., including, but not limited to, the algorithms described with reference to Figures 15A and 15B).

[0073] The input component 1330 may receive signals (e.g., signals indicative of the current and voltage obtained at the output of the disclosed bias supply apparatus). Additionally, the input component 1330 may receive phase information and / or synchronization signals between the bias supply apparatus 108 and the source generator 112, where the phase information and / or synchronization signals indicate one or more aspects of the environment within the plasma processing chamber 101 and / or synchronization control between the source generator and the single-switch bias supply apparatus. The signals received at the input component may include, for example, synchronization signals, power control signals to various generators and power supply units, or control signals from a user interface. Those skilled in the art will readily appreciate that any of a variety of types of sensors, such as, but not limited to, directional couplers and voltage-current (VI) sensors, can be used to sample power parameters such as voltage and current, and that signals indicative of the power parameters can be generated in the analog domain and converted to the digital domain.

[0074] Generally, the output components operate to provide one or more analog or digital signals to effectuate the opening and closing of switches and control of voltage sources as described herein.

[0075] The depicted transceiver component 1328 includes N transceiver chains that can be used to communicate with external devices over wireless or wired networks, each of which can represent a transceiver associated with a particular communication scheme (e.g., WiFi, Ethernet, Profibus, etc.).

[0076] 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 of which may be 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), the one or more computer-readable medium(s) having computer-readable program code embodied thereon.

[0077] As used herein, the phrase "at least one of A, B, or C" is intended to mean "any of A, B, or C, or any combination of A, B, and C." The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0078] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

[Claim 1] The invention as described in the drawings of this application.

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