High voltage plasma control

Abstract

The invention discloses a high-voltage pulse power supply system which comprises a direct-current power supply, a switching circuit electrically coupled with the direct-current power supply, a voltage drop control circuit coupled with the switching circuit and / or an output. The switching circuit includes a plurality of switching modules and generates a plurality of pulses. The voltage drop control circuit includes a voltage drop diode, a voltage drop inductor, and a voltage drop element. The voltage drop diode may be electrically coupled in series between the switching circuit and the transformer primary to allow a negative pulse portion of the pulse to pass from the switching circuit to the transformer primary. The voltage drop inductor and the voltage drop element may be arranged in series across the voltage drop diode to allow a negative pulse portion of the pulse to pass from the switching circuit to the transformer primary and / or store energy from the negative pulse portion of the pulse.

Description

Background Art

[0001] The use of radio frequency excited gas discharges in thin film and semiconductor manufacturing technologies has become standard. Positive ions generated in the plasma volume are accelerated in the plasma sheath and arrive at electrodes with an ion energy distribution function (IEDF) that is determined by the magnitude and waveform of the time-varying potential difference between the sheaths, the gas pressure, the physical geometry of the reactor, and / or other factors. The ion bombardment energy distribution can determine the degree of anisotropy of thin film etching, the amount of surface damage caused by ion impact, the aspect ratio and / or diameter and / or depth of holes and other etched features, the rate at which features are etched, etc. Controlling the IEDF is critical to the plasma etching process.

[0002] A high voltage power system is required to create the potential required to accelerate the ions within the plasma. The high voltage power system can provide a well-shaped power waveform (e.g., substantially flat between pulses) to create a variety of desired ion energy distribution functions. Different waveforms can be used on a pulse-by-pulse basis, each of which may produce a different ion energy distribution function, resulting in a completely different and convergent effective ion energy distribution function over time. Controlling the ion energy distribution function can control specific characteristics of the etching process.

[0003] In certain applications, the chamber or plasma may modify portions of the waveform that creates the ion energy distribution function. For example, in a semiconductor processing system, the ion current within the plasma may cause a voltage drop between successive pulses of the waveform at the wafer. These waveform changes may directly affect and / or alter the desired ion energy distribution function, thereby reducing the effectiveness of any process within the chamber. For example, a pulse-to-pulse voltage drop tends to broaden the ion energy distribution function and introduce more low energy ions. Summary of the invention

[0004] A high voltage pulse power supply system is disclosed. The high voltage pulse power supply system includes a DC power supply, a switching circuit electrically coupled to the DC power supply, a voltage drop control circuit coupled to the switching circuit, and an output. For example, the output can be coupled to a plasma chamber. The high voltage pulse power supply system can also include an energy recovery circuit. The switching circuit can include a plurality of switch modules arranged in a full bridge, a half bridge, or other bridge configurations, and can generate a plurality of pulses having a positive pulse portion and a negative pulse portion. The transformer can include a transformer core, a primary winding, and a secondary winding. The voltage drop control circuit can include a voltage drop diode, a voltage drop inductor, and / or a voltage drop element, which can be a resistive element or an energy recovery circuit. For example, the energy recovery circuit can be a collection of any electrical elements typically found in a DC-DC converter that moves energy from one potential to another.

[0005] For example, the voltage drop element can be any component or combination of components for regulating the amount of current flowing through the voltage drop inductor. The voltage drop element can work by limiting the energy injected into the voltage drop inductor so that a balanced current can be maintained, or a specified current can be maintained. Passive voltage drop elements such as fixed resistors allow a stable balanced current to be maintained, while active voltage drop elements allow the current flowing through the voltage drop inductor to vary over time. The voltage drop diode can be electrically coupled in series between the switching circuit and the primary winding of the transformer, and / or can allow the positive pulse portion of multiple pulses to be transferred from the switching circuit to the primary winding of the transformer. The inductor connected in series with the voltage drop diode can be specially selected to achieve a positive pulse with a specific shape. The inductor connected in series with the voltage drop diode can be set so that the forward pulse has a clean, round, sine-like shape without notches, dents or multiple peaks / ringings. The voltage drop inductor and the voltage drop element can be arranged in series at both ends of the voltage drop diode to allow the negative pulse portion of multiple pulses to be transferred from the switching circuit to the primary winding of the transformer. The combination of the voltage drop inductor and the voltage drop element can control how much energy is stored in the voltage drop inductor and / or how much current flows through the voltage drop inductor. The current flowing through the voltage drop inductor can be closely related to the voltage applied to the plasma and / or the ion energy distribution function created. The disclosed high voltage pulsed power supply system can, for example, change its output over time, whether pulse to pulse, burst to burst, or sequence to sequence, to create different, time-varying composite ion energy distribution functions.

[0006] The abstract and the various embodiments described herein are not intended to limit or define the scope of the disclosure or the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a circuit diagram of a high voltage pulse power supply and a plasma system.

[0008] Figure 2A and Figure 2B Shows Figure 1 The output waveforms of the high voltage pulse power supply and plasma system shown in .

[0009] Figure 3A and Figure 3B Shows Figure 1 The output waveforms of the high voltage pulse power supply and plasma system shown in .

[0010] Figure 4 It is a circuit diagram of a high voltage pulse power supply and a plasma system.

[0011] Figure 5A and Figure 5B Shows Figure 4 The output waveforms of the high voltage pulse power supply and plasma system shown in .

[0012] Fig. 6A and Figure 6B Shows Figure 4 The output waveforms of the high voltage pulse power supply and plasma system shown in .

[0013] Figure 7 It is a circuit diagram of a high voltage pulse power supply and a plasma system with an energy recovery circuit.

[0014] Fig. 8A and 8B Shows Figure 7 The output waveforms of the high voltage pulse power supply and plasma system shown in .

[0015] Fig. 9 Shows Figure 7 Output waveforms of medium and high voltage pulse power supplies and plasma systems.

[0016] Fig. 10A and 10B Shows Figure 7 The output waveforms of the high voltage pulse power supply and plasma system shown in .

[0017] Fig.11 Shows Figure 7 The output waveforms of the high voltage pulse power supply and plasma system are shown.

[0018] Fig.12 The invention discloses a circuit diagram of a high voltage pulse power supply and a plasma system having an active voltage drop control circuit.

[0019] Fig.13 Shows Fig.12 The output waveforms of the high voltage pulse power supply and plasma system are shown.

[0020] Fig.14A Shows Fig.12 The output waveforms of the high voltage pulse power supply and plasma system shown in .

[0021] Fig. 14B Shown is the method for generating Fig.14A Switching logic of the waveform shown.

[0022] Fig.15A Shows Fig.12 The output waveforms of the high voltage pulse power supply and plasma system shown in .

[0023] Fig. 15B Shows Fig.12 The output waveforms of the high voltage pulse power supply and plasma system shown in .

[0024] Fig.16A Shows Fig.12The output waveforms of the high voltage pulse power supply and plasma system shown in .

[0025] Fig. 16B Shown is the method for generating Fig.16A Switching logic of the waveform shown.

[0026] Fig.17A Shows Fig.16A A zoomed-in view of the waveform in .

[0027] Fig. 17B Shows Fig.16A A zoomed-in view of the waveform.

[0028] Fig. 17C Shows Fig.16A A zoomed-in view of the waveform.

[0029] Fig.17D Shows Fig.16A A zoomed-in view of the waveform.

[0030] Fig.18 Shows Fig.12 Ion energy distribution within the chamber of an example high voltage pulse power supply and plasma system shown in FIG.

[0031] Fig.19 Shows Fig.12 Ion energy distribution within the chamber of an example high voltage pulse power supply and plasma system shown in FIG.

[0032] Fig. 20A The low-end energy distribution function is shown.

[0033] Fig. 20B The low-end energy distribution function is shown.

[0034] Fig.21 It is a circuit diagram of a high voltage pulse power supply and a plasma system with a voltage drop control circuit and an energy control circuit.

[0035] Fig. 22 Shows Fig.21 The high voltage pulse power supply and ion energy distribution within the plasma system are shown.

[0036] Fig.23A The low-end energy distribution function is shown.

[0037] Fig. 23B The high end energy distribution function is shown.

[0038] Fig.24 A circuit diagram of a high voltage pulse power supply and a plasma system with an active voltage drop control circuit is shown.

[0039] Fig.25is a flow chart of an example plasma for controlling the voltage drop across a wafer between pulses.

[0040] Fig.25 is a flow chart of an example plasma controlling ion energy distribution on a wafer.

[0041] Fig.26 is a diagram showing example waveforms of two pulse trains.

[0042] Fig. 27 is a block diagram of a computing system that may be used or implemented to perform some embodiments described herein. DETAILED DESCRIPTION

[0043] A high voltage pulse power supply for generating high voltage pulses is disclosed. For example, the high voltage pulse power supply can be coupled to one or more plasma chambers. For example, the high voltage pulse power supply can compensate for voltage drops on a wafer within a plasma processing chamber. For example, the high voltage pulse power supply can provide energy recovery within a pulse circuit. For example, the high voltage pulse power supply can allow a narrow or specific ion energy distribution ("ion energy distribution function") to be created in a plasma. For example, the high voltage pulse power supply can allow a wide range of ion energy distribution functions to be created in a plasma. For example, the high voltage pulse power supply can allow an ion energy distribution function that varies over time to be created in a plasma. For example, the high voltage pulse power supply can allow operation at many different wafer voltage levels, which voltage levels can vary over time ("multi-level control") and / or the duration of the positive portion or the negative portion or both of the pulse can vary over time, and so on.

[0044] A pulse is a high voltage waveform that typically includes a voltage at a first voltage, quickly reaches a peak value of a second voltage for a short period of time, and then returns to about the first voltage. A pulse can be positive, negative, or bipolar (both positive and negative). A pulse can have a pulse width (e.g., full width, half peak), an amplitude (e.g., a second voltage), a rise time (e.g., the time it takes for the waveform to change from the first voltage to the second voltage), and / or a fall time (e.g., the time it takes for the waveform to change from the second voltage back to the first voltage).

[0045] A pulse train (or a train of pulses) is a series of pulses. A sequence (or a pulse train) is a train of multiple pulses. Fig.26 An example of a pulse sequence with two pulse trains is shown. Each pulse train has at least a pulse repetition frequency, a pulse train duration and / or a pulse train period.

[0046] The high voltage pulse power supply can compensate for the voltage drop (e.g., the slope of the voltage between pulses) on the wafer in the plasma processing chamber. For example, the voltage drop can be partially eliminated, completely eliminated, partially reversed, and / or completely reversed. For example, a wafer with a peak negative voltage of -6kV may experience a voltage drop of -2kV at the end of the negative portion of the pulse. For example, the high voltage pulse power supply can keep the wafer voltage at a constant -6kV or so during the entire negative pulse, during most of the negative pulse, or during part of the negative pulse, after which the wafer voltage drops. For example, the high voltage pulse power supply can also allow the wafer voltage to gradually become more negative over time, so that the wafer voltage changes from -6kV to -10kV during the negative portion of the pulse. For example, the high voltage pulse power supply can operate in the range of ±100V to ±100kV. The voltage range may include an absolute voltage range applied to the wafer, and a voltage range over which the power supply can change due to a drop in the wafer voltage. For example, the high voltage pulse power supply can control a negative wafer voltage greater than 100V.

[0047] The average power delivered by the high-voltage pulse power supply (averaged over many pulse trains and / or sequences) may be, for example, greater than 10W, 100W, 1000W, or 100kW. For example, the typical average power delivered by the high-voltage pulse power supply may be greater than 1kW. For example, the power output by the high-voltage pulse power supply in a single pulse train may be, on average, 1, 5, or 30 times the average output power.

[0048] The duration of the voltage drop control (eg, wafer waveform control) of the negative portion of the pulse may be, for example, 100 ns, 1 μs, 10 μs, 100 μs, and / or 1 ms.

[0049] For example, the positive portion of the pulse can be used to collapse the sheath / electron potential and scan electrons onto a wafer within a plasma processing chamber to neutralize charge accumulated when ion current flows to the wafer during the negative portion of the pulse. The positive portion of the pulse can operate, for example, for a duration of about 100 ns, 1 μs, 10 μs, 100 μs, and / or 1 ms. For example, the width and / or rise time of the positive portion of the pulse can be used to control the plasma potential relaxation time and the degree of ionization, among other plasma characteristics.

[0050] The high voltage pulse power supply can control the ratio of the positive portion of the pulse to the negative portion of the pulse. For example, the ratio may be between 1% and 100%. For example, the ratio can be set to control the magnetic flux within the transformer core, control various plasma properties, such as how the positive and negative plasma sheaths form and collapse, how much negative charge is transferred to the wafer during the positive portion of the pulse, and / or how much chamber wall etching occurs during the positive portion of the pulse, etc. The ratio can be set to optimize single or multiple aspects of the etching process and features. For example, if features with small size and high aspect ratio are required, the ratio can be set to the smaller end of its range, where the positive portion of the pulse is much shorter than the negative portion of the pulse. The ratio can be adjusted to keep the magnetic flux within the transformer core below 1T.

[0051] The high voltage pulse power supply can generate high voltage pulses with a plasma ion current between about 10 mA and about 300 A. The high voltage pulse power supply can generate high voltage pulses with an adsorption capacitance (for example, represented by capacitor 12) between about 0.3 nF and about 1,000 nF. The high voltage pulse power supply can generate high voltage pulses in a plasma with a neutral density between about 0.1 mT and about 1,000 mT and / or a plasma composed of a single gas or multiple gases. The high voltage pulse power supply can generate high voltage pulses in a plasma with an ionized particle count of 1015–1019 per cubic meter. The high voltage pulse power supply can generate high voltage pulses in a variety of plasma conditions and / or chamber types.

[0052] For example, an inductor 184 in series with a voltage drop diode 183 can help produce a positive pulse with a particular shape. The inductor 184 in series with the voltage drop diode 183 can be set so that the forward pulse has a clean, round, sine-like shape, such as without notches, dents, or multiple peaks / transient ringing, as shown in the pulse waveform 210 in FIG. 2. For example, the inductor 184 can vary between about 0.1nH and about 10H when measured on the primary side of the transformer. The inductor 184 can include and / or only include parasitic stray inductance (no physical components). The inductor 184 can be, for example, less than about 100nH.

[0053] The high voltage pulse power supply may include an energy recovery circuit (e.g., Figure 7 and Fig.12As shown). The energy recovery circuit may, for example, include a DC-DC converter (e.g., a rectifier bridge 730) that converts energy from one voltage level to another voltage level. For example, the energy recovery circuit may operate at a voltage between about 1V and about 5,000V. For example, the energy recovery circuit may operate at a power level between about 10W and 100kW. For example, the energy recovery circuit may be represented as a simple DC-DC converter that operates between two fixed voltages that remain constant over time or vary over time. The time required for a DC-DC converter (direct current-to-direct current converter) to adjust its operating voltage range is about 1 second to 1 millisecond. For example, the DC-DC converter may be based on various bridge topologies, such as a half bridge or a full bridge, as well as many possible topologies. For example, the energy recovery circuit may recover energy that would otherwise be lost from a circuit (e.g., a voltage drop inductor). While recovering the energy, the energy recovery circuit may, for example, adjust the current flowing through the voltage drop inductor and / or adjust the voltage waveform and / or amplitude applied to the wafer and / or plasma.

[0054] For example, a high voltage pulse power supply can produce a narrow ion energy distribution function within a plasma by reducing and / or eliminating wafer voltage drops. For example, a uniform voltage maintained in a plasma can produce a narrow ion energy distribution function. When a high voltage pulse power supply changes the voltage waveform applied to a plasma, a wide range of ion energy distribution functions can be created in a plasma, for example, these functions can range from a very sharp function (e.g., see Fig. 22 ) to a flat function, and an ion energy distribution function similar to that created by a standard sinusoidal power supply used for plasma etching.

[0055] For another example, a high voltage pulse power supply can generate an ion energy distribution function that varies with time. For example, the high voltage pulse power supply can adjust the wafer voltage and / or the wafer waveform (e.g., pulse width, pulse repetition frequency, period between pulses, etc.) from one pulse to another, from one pulse train to another, and / or from one pulse sequence to another. For example, a series of pulses, each pulse having a peak ion energy distribution function at a different position, can be combined to create a substantially flat composite ion energy distribution function. Such a composite ion energy distribution function can be created by, for example, any number of pulses containing any distributed waveform, voltage, and / or ion energy distribution function.

[0056] The high voltage pulse power supply can create any composite ion energy distribution function. The ion energy distribution function can be programmed and / or adjusted in real time to optimize various wafer etching parameters or ion energy distribution function parameters, such as etching rate, mask erosion rate, feature aspect ratio, feature bow growth rate, feature profile, feature size, bottom hole diameter, etc. An ion energy distribution function can be created, for example, in which 90% of the ions fall within a band representing 10% of the total width of the energy distribution and / or in which the distribution is almost flat throughout its entire range. The ion energy distribution function can change on a time scale as low as 100 μ seconds, for example, or on a time scale between about 10 seconds and about 100 seconds. The rate at which the ion energy distribution function changes can be set, for example, by adjusting the rate at which the DC voltage level at which the high voltage pulse power supply operates through an energy recovery circuit.

[0057] High voltage pulse power supplies can allow operation at many different wafer voltage levels (or voltage states) that vary over time in discrete pulse trains or sequences, such as Fig.16A This operation can be called multi-level control or two-level control.

[0058] For example, when current flows in the negative portion of the applied waveform, the voltage in the plasma chamber may drop (e.g., Figure 2B The drop 221 shown). For example, this drop can charge the plasma surface and / or discharge the series capacitor, which can cause the voltage seen by the plasma to drop over time. For example, this often occurs in semiconductor plasma etching plasmas because the etching current flows to the wafer surface and reduces the voltage across the adsorption capacitor. As the voltage across the adsorption capacitor drops, the etching voltage (i.e., the voltage applied across the plasma) will also drop.

[0059] The voltage drop can be controlled by the following equation Where I is the plasma current flowing into the plasma and C is the series capacitance (e.g., wafer clamping capacitance (e.g., capacitor 12)). dV / dt is the rate at which the voltage across the series capacitance changes due to the flow of plasma current in the etching plasma. When the plasma current flows into the series capacitance, it changes according to the equation Release the voltage built up when the series capacitor is charged at the beginning of the pulse. The high voltage pulse power supply can be operated in a way to eliminate the drop in voltage between the series capacitor and the plasma, for example, by preventing the series capacitor from discharging. It can do this by applying a ramp voltage to the other side of the relevant series capacitor, which effectively cancels the dV / dt voltage drop caused by the ion current flow, thereby maintaining a constant voltage between the series capacitor and the plasma.

[0060] To eliminate the voltage drop caused by the ion and / or etching current, the high voltage pulse power supply can create an additional voltage drop and / or voltage change on the other side of the series capacitor to offset the voltage drop that would otherwise occur. A voltage drop inductor (e.g., voltage drop inductor 187) can, for example, establish the ramp voltage required to maintain a constant plasma voltage between pulses.

[0061] If the voltage drop inductor is sized to maintain a relatively constant current during the pulse, for example, when the current is matched to the plasma ion and / or etching current, the natural operation of the voltage drop inductor will impose the desired dV / dt on the opposite side of the series capacitor so that the voltage across the plasma and the series capacitor remains constant. Since the current flowing through the voltage drop inductor is offset from the ion current flowing in the plasma during the negative portion of the pulse, the ion energy distribution function and the corresponding voltage drop across the plasma will change accordingly. The current flowing through the voltage drop inductor can set the voltage and / or voltage waveform in the plasma.

[0062] The high voltage pulse power supply can control the current flowing through the voltage drop inductor. For example, the voltage drop inductor can include physical elements, such as stray inductance in an inductor and / or other circuit elements. The voltage drop inductor and / or the energy recovery circuit can control the current flowing through the voltage drop inductor.

[0063] The size of the voltage drop inductor can be set anywhere between about 1 μH to about 10 mH. The size of the voltage drop inductor can be used to set specific characteristics of the desired waveform, as well as adjust the rate of the waveform applied to the plasma, among other factors.

[0064] Ion energy distribution is an important factor in semiconductor plasma processing. For example, a relatively flat and low ion energy distribution versus a sharp ion energy distribution at a specific energy level can improve etching or other processes. For example, this can focus most of the energy from the power supply into the plasma at a specific energy level. The high voltage pulse power supply disclosed herein may be able to control the ion energy distribution within the plasma.

[0065] Real-time feedback and control can be used to control the voltage waveform applied to the wafer. The voltage waveform can be measured directly at or near the chamber or wafer (e.g., at point 134 and / or point 135) and / or calculated based on current and voltage measurements from other circuit elements. For example, the amount of energy recovered and / or dissipated in the energy recovery circuit can be adjusted to create a specific wafer voltage waveform. For example, the amount of current flowing through the voltage drop inductor (e.g., voltage drop inductor 187) can be adjusted by real-time feedback to optimize plasma and wafer etching parameters (e.g., ion energy distribution function). The time scale of real-time feedback and control may be faster than 1Hz, 1kHz, or 100kHz. Active energy recovery circuits can achieve such real-time feedback and control. Passive energy recovery circuits can also allow real-time feedback and control using variable passive elements (e.g., time variable resistors). Real-time feedback and control adjustments can include, for example, the width of the positive portion of the pulse (e.g., rise time), the width of the negative portion of the pulse (e.g., fall time), the time between the positive and negative portions of the pulse, the pulse repetition frequency, the switch timing signal, etc. Multiple timing elements can be used to achieve real-time feedback and control. Real-time feedback and control can be achieved by varying the voltage applied to the pulse power supply.

[0066] Figure 1 1 is a circuit diagram of a high voltage pulse power supply and plasma system 100. The high voltage pulse power supply and plasma system 100 may include, for example, a high voltage pulse power supply 105 and a plasma chamber 106. The plasma chamber 106 represents an active circuit of a plasma in the plasma chamber.

[0067] The high voltage pulse power supply 105 is shown as a full bridge configuration, but can also be operated in a half bridge configuration or any other bridge configuration. The high voltage pulse power supply 105 can include a plurality of switch modules in a full bridge configuration, which are coupled to the DC power supply 150 and the energy storage capacitor 155 and the DC power supply 151 and the energy storage capacitor 156. The energy storage capacitor 156 and the DC power supply 151 are switched through the switch module 162 and the switch module 164 to generate positive pulses. The energy storage capacitor 155 and the DC power supply 150 are switched through the switch module 161 and the switch module 163 to generate the negative pole of each pulse. The DC power supply 150 and the DC power supply 151 can be the same power supply, and the energy storage capacitor 155 and the energy storage capacitor 156 can be the same capacitor charged to the same voltage. The charging voltage range of the DC power supply 150 and the DC power supply 151 can be, for example, between about 0 and about 1,000V, or between about 0 and about 3,000V.

[0068] The high voltage pulse power supply 105 may be coupled to a voltage drop control circuit 110. The voltage drop control circuit 110 may, for example, be coupled to a transformer 145. The voltage drop control circuit 110 may, for example, mitigate or reduce a voltage drop within a plasma chamber, such as on a wafer within the plasma chamber.

[0069] The high voltage pulse power supply and plasma system 100 can generate bipolar pulses, for example. For example, the bipolar pulse can generate a pulse including a positive pulse and a negative pulse. The bipolar pulse can be described as a single pulse having a positive pulse portion and a negative pulse portion, such as Figure 2A and Figure 2B The output waveform 205 and the wafer waveform 210 are shown in FIG. The peak-to-peak voltage between the positive pulse and the negative pulse can be greater than about 500V, 1kV, 2kV, 5kV, 10kV, 15kV, 20kV, 100kV, etc.

[0070] The high voltage pulse power supply and plasma system 100 can, for example, generate pulses including positive pulses, the peak voltage of which can be greater than about 250V, 500V, 1kV, 2kV, 5kV, 10kV, 15kV, 100kV, etc. The high voltage pulse power supply 105 can, for example, generate pulses including negative pulses, the negative pulses having a negative peak voltage less than about -250V, -500V, -1kV, -2kV, -5kV, -10kV, -15kV, -100kV, etc.

[0071] The high voltage pulse power supply and plasma system 100 can, for example, generate a high pulse repetition frequency (e.g., a frequency greater than 1 kHz, 10 kHz, 100 kHz, 200 kHz, 500 kHz, 1 MHz, etc.), a fast rise time (e.g., a rise time of less than about 1 ns, 10 ns, 50 ns, 100 ns, 250 ns, 500 ns, 1,000 ns, 10 s, etc.), a fast fall time (e.g., a fall time of less than about 1 ns, 10 ns, 50 ns, 100 ns, 250 ns, 500 ns, 1,000 ns, 10 μs, etc.), and / or a short pulse width (e.g., a pulse width of less than about 10 μs, 1,000 ns, 500 ns, 250 ns, 100 ns, 20 ns, etc.).

[0072] The high voltage pulse power supply and plasma system 100 can, for example, generate pulses including a combination of pulses, which can include any combination of positive pulses, negative pulses, and / or bipolar pulses.

[0073] The high voltage pulse power supply and plasma system 100 may include, for example, a high voltage pulse power supply 105 . The high voltage pulse power supply 105 may be, for example, a half-bridge circuit or a full-bridge circuit. The high voltage pulse power supply 105 may include a DC power supply 150 with an energy storage capacitor 155 .

[0074] The high voltage pulse power supply 105 may include, for example, four switch modules 161, 162, 163, 164. For example, each of the switch modules 161, 162, 163, and 164 may include any number of solid-state switches arranged in series or in parallel. The switch modules 161, 162, 163, and 164 may include, for example, any type of solid-state switch, such as an IGBT, a MOSFET, a SiCMOSFET, a SiC junction transistor, a FET, a SiC switch, a GaN switch, a photoconductive switch, and the like. The switch modules 161, 162, 163, and 164 may switch at a high frequency and / or may generate high voltage pulses. These frequencies may include, for example, frequencies of about 10kHz, 400kHz, 0.5MHz, 2.0MHz, 4.0MHz, 13.56MHz, 27.12MHz, 40.68MHz, 50MHz, and the like. These frequencies may, for example, be greater than 10kHz. Each switch module 161, 162, 163, and 164 may or may not include the same number or type of solid-state switches as the other switch modules.

[0075] Each switch in the switch modules 161 , 162 , 163 , and 164 may include one or more solid-state switches S1 (eg, solid-state switches such as IGBTs, MOSFETs, SiC MOSFETs, SiC junction transistors, FETs, SiC switches, GaN switches, photoconductive switches, etc.).

[0076] Each switch in the switch modules 161, 162, 163, 164 may be coupled in parallel with a corresponding bridge diode 171, 172, 173, 174 and may include stray inductance and / or stray resistance. Multiple diodes may be used for each switch, while some switches may not have a diode associated therewith, and other switches may share one or more diodes. For example, the stray inductance of the switch modules may be equal. The stray inductance of the switch modules may be, for example, less than about 10nH, 50nH, 100nH, 150nH, 500nH, 1,000nH, etc. The stray inductance of each switch module may be, for example, less than about 200nH. The stray inductance of each switch module may be, for example, between about 100nH and about 500nH. The combination of the switch module and the corresponding bridge diode may be coupled in series with the corresponding bridge inductor.

[0077] Transformer 145 (or transformer T1 ), for example, may include a transformer as disclosed in US Patent Application No. 15 / 365,094, entitled “High Voltage Transformer,” which is incorporated herein for all purposes.

[0078] For example, the duty cycle of the switch module can be adjusted by changing the duty cycle of the signal Sig1, which turns on and off the switch module 161 and the switch; the duty cycle of the switch module can be adjusted by changing the duty cycle of the signal Sig2, which turns on and off the switch module 162; the duty cycle of the switch module can be adjusted by changing the duty cycle of the signal Sig3, which turns on and off the switch module 163; and the duty cycle of the switch module can be adjusted by changing the duty cycle of the signal Sig4, which turns on and off the switch module 164.

[0079] For example, each switch module 161, 162, 163 or 164 in the high voltage pulse power supply 105 can be switched independently or switched in combination with one or more other switch modules. For example, the signal Sig1 can be the same signal as the signal Sig3. As another example, the signal Sig2 can be the same signal as the signal Sig4. As another example, each signal can be independent, and each switch module 161, 162, 163 or 164 can be controlled independently or individually.

[0080] The high voltage pulse power supply and plasma system 100 may not include a conventional matching network, such as a 50Ω matching network or an external matching network or an independent matching network. In fact, the embodiments described herein do not require a 50Ω matching network to adjust the switching power applied to the wafer chamber. In addition, the embodiments described herein provide a variable output impedance RF generator that does not require a conventional matching network. This can allow for rapid changes in the power consumed by the plasma chamber. Typically, the adjustment of the matching network requires at least about 100 μs to about 200 μs. For example, the power change can occur within one or two RF cycles, for example, about 2.5 μs to about 5.0 μs at a frequency of about 400 kHz.

[0081] The high voltage pulse power supply 105 can be replaced by a half-bridge circuit with two switch modules, for example. For example, the high voltage pulse power supply 105 can provide power in a variety of configurations. For example, multiple power supplies and energy storage capacitor combinations can be used to power a full bridge (or half bridge), such as Figure 1 and Fig.24 As another example, a single power supply and storage capacitor combination can be used to power a full bridge (or half bridge), as shown in Figure 7 , Fig.12 and Fig.21 shown.

[0082] The voltage drop control circuit 110 may include a voltage drop inductor 187 coupled in series with the voltage drop resistor 186. The series combination of the voltage drop inductor 187 and the voltage drop resistor 186 may be arranged in parallel or connected across the voltage drop diode 183 and / or the inductor 184.

[0083] The voltage drop diode 183 may include, for example, one or more diodes arranged in series or in parallel. For example, the rated carrying current of the voltage drop diode 183 may be greater than about 100 amperes. For example, the rated carrying current of the voltage drop diode 183 may be greater than about 10, 100, 1000, 10,000, etc.

[0084] The inductor 184 may include, for example, a physical inductor and / or represent parasitic inductance and / or stray inductance. The parasitic inductance and / or stray inductance may include, for example, the inductance of components between the high voltage pulse power supply 105 and the plasma chamber 106 and / or the inductance of the transformer 145. The inductor 184 may have, for example, an inductance of about 0.1 nH, 1 nH, 10 nH, 100 nH, 1 μH, or 10 μH. The inductor 184 may have, for example, an inductance of less than about 500 nH.

[0085] For example, the inductance value of inductor 184 may be set so that the positive pulse has a nice sinusoidal top. If the inductance value of inductor 184 is too small, the instantaneous ringing on the positive pulse will be too short, and the step in the positive pulse may occur at a later time. For example, if the inductance value of inductor 184 is too small, then ringing may be seen at the top of the positive pulse. For example, if the inductance value of inductor 184 is too large, the smooth sinusoidal top will not be completed in time, and the sinusoidal wave may be truncated. For example, if the inductance value of inductor 184 is too large, then the positive pulse may increase while the positive pulse is truncated by the transition to a negative pulse.

[0086] The voltage drop control circuit 110 controls the voltage ramp across the transformer 145 so that the peak voltage is reached in the later stages of the pulse. The drop inductor 187 is energized during the negative voltage portion of the bipolar pulse while the drop resistor 186 extracts energy from the drop inductor 187. The shape of the applied negative pulse in combination with the drop resistor 186 sets the balancing current in the drop inductor 187. For example, the pulse-to-pulse ripple of the balancing current may be less than 1%, 5%, 20%, or 100% of its average value. For example, the drop inductor may have an inductance such that during a train of pulses, balance is reached in less than the first 2, 5, 70, or 100 pulses. For example, the drop inductor 187 may have an inductance that allows the balancing current through the drop inductor 187 to be reached in less than 20 pulses. During the positive portion of the pulse of the bipolar pulse, current flows through the drop diode 183 and the inductor 184 into the transformer 145.

[0087] Inductor 184 may have an inductance of, for example, about 0.1 nH, 3 nH, 100 nH, or 10 μH. Typically, it is set to be less than 200 nH. For example, drop inductor 187 may have an inductance of about 1 μH, 10 μH, 100 μH, or 3000 μH.

[0088] The voltage drop resistor 186 may have a resistance of, for example, about 0.01 ohms, 0.3 ohms, 30 ohms, or 100 ohms. It is typically set to less than 4 ohms.

[0089] For example, plasma chamber 106 may represent an idealized or effective circuit of a semiconductor processing chamber, such as a plasma deposition system, a semiconductor manufacturing system, a plasma sputtering system, a plasma etching system, etc. The capacitance of capacitor 12 may, for example, represent the capacitance of an electrostatic chuck on which a semiconductor processing wafer may be placed. For example, the chuck may include a dielectric material (e.g., alumina or other ceramic material and a conductor contained within the dielectric material). For example, capacitor 23 may have a small capacitance (e.g., approximately 10 pF, 100 pF, 500 pF, 1 nF, 10 nF, 100 nF, etc.).

[0090] For example, capacitor 13 can represent the sheath capacitance between the plasma and the wafer. For example, resistor 56 can represent the sheath resistance between the plasma and the wafer. For example, inductor 40 can represent the sheath inductance between the plasma and the wafer. For example, current source I2 can represent the ion current through the sheath. For example, capacitor 23 or capacitor 13 can have a small capacitance (e.g., about 10 pF, 100 pF, 500 pF, 1 nF, 10 nF, 100 nF, etc.).

[0091] For example, capacitor 18 can represent the plasma sheath capacitance to the chamber wall. For example, resistor 57 can represent the resistance between the plasma and the chamber wall. For example, current source I1 can represent the ion current in the plasma. For example, capacitor 23 or capacitor 18 can have a small capacitance (e.g., about 10 pF, 100 pF, 500 pF, 1 nF, 10 nF, 100 nF, etc.).

[0092] The plasma chamber may include one or more electrodes that can be used to ignite the plasma and / or drive the plasma. The one or more electrodes may be electrically coupled to a high voltage pulse power supply.

[0093] Figure 2A and Figure 2BAn output waveform 205 at point 134 and a wafer waveform 210 at point 135 are shown in an example circuit of a high voltage pulse power supply and plasma system 100. For example, the wafer waveform 210 can show the voltage on a wafer within a plasma chamber (e.g., a dielectric etching plasma chamber). Waveform 215 shows the switching logic of the SIG±2 switch module 162 and the switch module 164. Waveform 220 shows the switching logic of the SIG±1 switch module 161 and the switch module 163. As shown, the portion of the output waveform 205 between pulses has a negative slope, which causes the portion of the wafer waveform 210 between pulses to be substantially flat.

[0094] For example, the output waveform 205 is created by a 600V charging voltage from the DC power supply 151, a positive pulse width of 450ns, and a negative pulse width of 1,950ns. In this example, the voltage drop inductor 187 is approximately 6μH, the resistance of the voltage drop resistor 186 is 0.5 ohms, and the inductance of the inductor 184 is approximately 16nH. For example, this can mitigate or reduce the voltage drop within the plasma chamber, for example, on the wafer within the plasma chamber, as shown by the flat portion of the wafer waveform 210 between the two positive pulses.

[0095] Figure 2B It is also an example of two high voltage pulses. Each pulse of the wafer waveform 210 has a positive pulse portion 211 and a negative pulse portion 212. The positive pulse portion 211 is the portion of the pulse where the voltage is greater than zero, and the negative pulse portion 212 is the portion of the pulse where the voltage is less than zero. Between the negative pulse portion 212 and the positive pulse portion 211, the pulse may have a fast rise time (i.e., a steep positive slope). And between the positive pulse portion 211 and the negative pulse portion 212, the pulse may have a fast fall time (i.e., a steep negative slope). For example, the fall time may be slower than the rise time.

[0096] Between the positive pulse portions 211, for example, there may be an upper relatively flat portion (or at least a gradually rising and / or falling slope). The positive pulse portion 211 may have any length. For example, the negative pulse portion 212 may have a lower relatively flat portion (or at least a gradually rising and / or falling slope). For example, the negative pulse portion 212 may have any length. The length of the negative pulse portion 212 may be longer than the length of the positive pulse portion 211.

[0097] The height of the positive pulse portion 211 relative to the negative pulse portion 212 is the amplitude of the pulse. The time between consecutive positive pulse portions 211 can be the pulse period, and the inverse of the pulse period can be the pulse repetition frequency. The pulse waveform is not a sinusoidal waveform or a radio frequency waveform. In fact, an ideal pulse waveform on a wafer (e.g., wafer waveform 210) is more like a square wave than a sinusoidal waveform. In addition, a sinusoidal waveform cannot have a fast rise time and / or a fast fall time, a long upper relatively flat portion and / or a lower flat portion, which is not necessarily the case with a pulse waveform. In addition, in a sinusoidal waveform, the positive pulse portion 211 and the negative pulse portion 212 have approximately the same length, which is not necessarily the case with a pulse waveform.

[0098] Figure 2B The output waveform 205 in FIG. 2 shows an example drop 221 between pulses. As shown, the drop between pulses is a negative slope in the negative pulse portion 212.

[0099] For example, a lower output voltage can be achieved by adjusting the timing constraints to keep the charging voltage substantially constant. This can be referred to as multi-state operation, which includes a series of pulses with different voltages. For example, multi-state operation can be achieved by adjusting the positive and negative pulse widths, such as Figure 3A and Figure 3B , which shows the output waveform 305 at point 134 and the wafer waveform 310 at point 135. Figure 3A In the example, a positive pulse of 50 ns and a negative pulse of 350 ns are used. Figure 3B The positive pulse width is 90ns and the negative pulse width is 2,310ns.

[0100] For example, multi-state operation may be achieved by increasing the value of the voltage dropping resistor 186, where a higher resistance value may result in a lower output voltage. Figure 3B The waveform is shown when the voltage drop resistor 186 is set to 6 ohms, instead of generating Figure 2B When using 0.5 ohm.

[0101] Figure 41 is a circuit diagram of an example high voltage pulse power supply and plasma system 400. The voltage drop resistor 186 in the plasma system 100 has been replaced by a voltage drop capacitor 486 connected in series with a voltage drop inductor 187. The voltage drop capacitor 486 can, for example, have a capacitance of about 10mF, 25mF, 50mF, 100mF, 250mF, 500mF, 1,000mF, 38F, 200F, etc. The voltage drop capacitor 486 can, for example, extract energy from the voltage drop inductor. Although the voltage drop resistor 186 dissipates energy in the form of ohmic losses, the voltage drop capacitor 486 can convert energy into stored capacitive energy. The stored energy can, for example, increase the potential difference across the voltage drop capacitor 486. For example, the stored energy can be recovered by an energy recovery circuit (e.g., an energy recovery circuit 701 or an active voltage drop control circuit 1201 or an energy compensation circuit 2101) so that the voltage across the voltage drop capacitor 486 remains approximately constant during the pulse train. The energy recovery circuit may include, for example, a DC-DC converter that maintains the voltage on the voltage drop capacitor 486 while delivering excess energy to the high voltage pulse power supply 105. When the energy recovery circuit is used, the value of the voltage drop capacitor 486 may be less than about 100 mF, 10 mF, 100 μF, 10 μF, or 1 μF. Typically, for a full-bridge topology, the value is set to less than about 30 μF, and for a half-bridge topology, the value is set to less than about 100 μF.

[0102] Figure 5A and Figure 5B An output waveform 505 measured at point 134 of the high voltage pulsed power supply and plasma system 400 and a wafer waveform 510 measured at point 135 in an example circuit of the high voltage pulsed power supply and plasma system 400 are shown. For example, the wafer waveform 510 can show the voltage across a wafer within a plasma chamber. Waveform 515 shows the switching logic of the SIG±2 switch module 162 and switch 164. Waveform 520 shows the switching logic of the SIG±1 switch module 161 and switch 163. As shown, the portion of the output waveform 505 between pulses has a negative slope, which causes the portion of the wafer waveform 510 between pulses to be substantially flat.

[0103] For example, the output waveform 505 and the wafer waveform 510 may be created using a 600V charging voltage from a DC power supply, a 450ns positive pulse width, and a 1950ns negative pulse width. An initial charge of -270V may be added across the voltage drop capacitor 486. Figure 5A and Figure 5B In the example shown, the voltage dropping capacitor 486 may have a capacitance of approximately 200 mF.

[0104] Fig. 6A and Figure 6BAn output waveform 605 at point 134 and a wafer waveform 610 at point 135 are shown. Fig. 6A A waveform with a positive pulse width of 50 ns and a negative pulse width of 350 ns is shown. Figure 6B A waveform with a positive pulse width of 90ns, a negative pulse width of 2310ns, and an initial charging voltage of -575V on the voltage drop capacitor is shown.

[0105] Figure 7 is a circuit diagram of a high voltage pulse power supply and plasma system 700, which may include a power supply 705 coupled to a plasma chamber 106. The high voltage pulse power supply and plasma system 700 may include a voltage drop control circuit 110 and / or an energy recovery circuit 701. The power supply 705 may be similar to the high voltage pulse power supply 105, having a DC power supply 150 and an energy storage capacitor 155.

[0106] The energy recovery circuit 701 is coupled to the voltage drop inductor 187 of the voltage drop control circuit 110. The energy recovery circuit 701 may also be coupled to the DC power supply 150 and the energy storage capacitor 155. The energy recovery circuit 701 may include a DC-DC converter coupled between the voltage drop control circuit 110 and the energy storage capacitor 155, for example.

[0107] The energy recovery circuit 701 may include a switch module 731 and a switch module 732 arranged in a half-bridge configuration (a full-bridge configuration or other bridge configurations may also be used). Each switch module 731, 732 may include a corresponding switch diode 741, 742. The energy recovery circuit 701 may also include a transformer 715 coupled to the switch module 731 and / or the switch module 732. The transformer 715 may be inductively coupled to the rectifier bridge 730, which is coupled to the energy storage capacitor 155 through the energy recovery inductor 706 and / or the energy recovery diode 710. For example, the energy recovery diode 710 may allow charge from the voltage drop capacitor 720 and / or the voltage drop capacitor 725 to flow to charge the energy storage capacitor 155. The value of each component in the energy recovery circuit may be set to allow the voltage on the voltage drop capacitor 720 and the voltage drop capacitor 725 to change in a time of less than, for example, 2 pulses, 20 pulses, or 200 pulses.

[0108] For example, the energy recovery inductor 706 may have a low inductance. The energy recovery inductor 706 may have an inductance of, for example, less than about 1 nH, 10 nH, 50 nH, 100 nH, 150 nH, 500 nH, 1,000 nH, etc. The energy recovery inductor 706 may include, for example, the inductance of the rectifier bridge 730, the transformer 715, the switch module 731, and / or the switch module 732.

[0109] For example, switch module 731 and / or switch module 732 may be turned on or off to control the amount of energy removed from voltage drop inductor 187. This may be accomplished, for example, by adjusting the duty cycle of switch module 731 and / or switch module 732. This may be accomplished, for example, based on feedback from one or more sensors monitoring the voltage at capacitor 12.

[0110] The energy recovery circuit 701 can, for example, transfer energy from the voltage drop inductor 187 to charge the energy storage capacitor 155. The energy recovery circuit 701 is coupled across the voltage drop capacitor 720 and / or the voltage drop capacitor 725.

[0111] Fig. 8A and 8B An output waveform 805 at point 134 and a wafer waveform 810 at point 135 are shown in an example circuit of a high voltage pulsed power supply and plasma system 700. As shown, the portion of the output waveform 805 between pulses has a negative slope, which causes the portion of the wafer waveform 810 between pulses to be substantially flat.

[0112] In this example, a 600V charging voltage output can be created using a DC power supply with a positive pulse width of 450ns and a negative pulse width of 1950ns. In this example, the switching frequencies of switch module 731 and switch module 732 are both set to 250kHz. Typical operating frequencies may be greater than 1kHz, 10kHz, 100kHz, or 3MHz. In this example, each switch is closed for about 1.65μs, equivalent to 8 duty cycles of about 2.5%. In this example, the initial charging voltage applied across the voltage drop capacitor 720 and / or the voltage drop capacitor 725 is about -135V, with a total initial charging voltage of -270V across the two capacitors. In this example, each of the voltage drop capacitor 720 and / or the voltage drop capacitor 725 has a capacitance of about 25μF, but other values ​​may also be used, such as less than about 1μF, 33μF, 500μF, or 3mF. The specific value of the capacitor can be selected to set the ripple of the plasma current and the rate at which the wafer voltage is adjusted by the action of the energy recovery circuit. For example, a typical adjustment time may be greater than about 0.1 microseconds, 1 millisecond, or about 10 minutes. Although this initial electromotive force enables the output voltage to quickly reach equilibrium, the energy recovery circuit duty cycle maintains the equilibrium.

[0113] Fig. 9 An output waveform 905 at point 134 and a wafer waveform 910 at point 135 are shown in an example circuit of a high voltage pulse power supply and plasma system 700. In this example, no initial electromotive force is applied to the voltage drop capacitor 720 and / or the voltage drop capacitor 725. In this example, the output voltage still reaches equilibrium.

[0114] Fig. 10A and Fig. 10B The output waveform 1005 at point 134 and the wafer waveform 1010 at point 135 of the example circuit of the high voltage pulse power supply and plasma system 700 are shown. In this example, the circuit values ​​are the same as those used to generate Fig. 8A and 8B The circuit values ​​for the waveforms shown in are the same, but Fig. 10A The timing is 50 nanoseconds for positive pulse and 350 nanoseconds for negative pulse. Fig. 10B The timing is 90 nanoseconds for the positive part of the pulse and 2310 nanoseconds for the negative part of the pulse. In this example, the duty cycle of the energy recovery circuit is reduced to 15%. The duty cycle of the energy recovery circuit can range from 0% to 100%, which is a typical feature of a DC-DC converter.

[0115] Fig.11 The output waveform 1105 at point 134 and the wafer waveform 1110 at point 135 of the example circuit of the high voltage pulse power supply and plasma system 700 are shown. In this example, the output voltage switches between a high voltage pulse train 1120 of about 27.5 μs, a multi-state pulse train 1125 of about 32.5 μs, and a high voltage pulse train 1130 of about 27.5 μs. The conversion can occur by simply setting / programming the voltage across the voltage drop capacitor 720 and / or the voltage drop capacitor 725 using the energy recovery circuit. Increasing the voltage across these capacitors may result in lower voltage and / or multi-stage operation, while reducing the voltage across these capacitors may result in higher voltage operation. By adjusting the voltage across these capacitors, the energy recovery circuit or DC-DC converter can be used to create any general combination of output voltages to form any desired time-related pattern. During the transition from the high voltage pulse train 1120 to the multi-state pulse train 1125, the transformer flux may swing negatively for several transition pulse trains 1125A. For example, the multi-state positive pulse width may be adjusted and / or the multi-state negative pulse width may be reduced to avoid transformer saturation during this transition period, thereby reducing the negative magnetic flux injected into the transformer core.

[0116] Fig.12 1 is a circuit diagram of a high voltage pulse power supply and a plasma system 1200 having an active voltage drop control circuit 1201. The active voltage drop control circuit 1201 may also include, for example, an energy recovery element (e.g., an energy recovery inductor 1225 and a diode 1226) for recovering energy from the voltage drop inductor 187 to the energy storage capacitor 156.

[0117] The high voltage pulse power supply and plasma system 1200 includes a high voltage pulse power supply 705 coupled to an active voltage drop control circuit 1201 and a plasma chamber 106 .

[0118] The active voltage drop control circuit 1201 may include, for example, a voltage drop inductor 187 coupled in series with a voltage drop capacitor 486 and a second voltage drop inductor 1205. The total voltage drop inductance may be evenly divided between the voltage drop inductor 187 and the voltage drop inductor 1205, or may be unevenly divided between the voltage drop inductor 187 and the voltage drop inductor 1205. Selecting the precise division may simplify the design and construction of each individual inductor. A switching circuit (e.g., a half-bridge switching circuit or a full-bridge switching circuit) may be coupled across the voltage drop capacitor 486. The switching circuit may also be coupled to a transformer 1210.

[0119] The active voltage drop control circuit 1201 may include, for example, a switch module 1215, a switch module 1216, a switch module 1217, a switch module 1218, a transformer 1210, a diode rectifier bridge 1220, an energy recovery inductor 1225, and / or an energy recovery diode 1226. For example, the diode rectifier bridge 1220 may be coupled to the energy recovery inductor 1225 and the transformer 1210, or located between the energy recovery inductor 1225 and the transformer 1210. The energy recovery inductor 1225 may be coupled to the energy storage capacitor 156 as part of the power supply 705.

[0120] Charge may be removed from and / or added to the voltage drop capacitor 486 by controlling the timing of switches in the active voltage drop control circuit 1201. The active voltage drop control circuit 1201 may be or include any converter that moves energy from the voltage drop capacitor 486 to the energy storage capacitor 156 or moves energy from the energy storage capacitor 156 to the voltage drop capacitor 486.

[0121] The active voltage drop control circuit 1201 may include or comprise any of various forms of DC-DC converters, for example. The active voltage drop control circuit 1201 may include, for example, a set of switches, transformers, rectifier stages, and filter inductors arranged in a bridge configuration. An example function of the active voltage drop control circuit 1201 may be to regulate the voltage across the voltage drop capacitor 486. This may be done, for example, on a desired time scale to produce a desired wafer voltage waveform and / or plasma voltage waveform.

[0122] The voltage drop capacitor 486 may have a value of less than about 10 mF, 1 mF, 20 μF, or 1 μF. For example, the voltage drop capacitor 486 may have a value of less than about 100 μF. For example, the specific value of the voltage drop capacitor 486 may be selected to allow and / or facilitate the ability of the active voltage drop control circuit 1201 to adjust the voltage across the voltage drop capacitor 486 on a desired time scale. The time scale of adjustment may be greater than about 1 microsecond, 1 millisecond, or 1 hour. A smaller inductance value of the voltage drop capacitor 486 may, for example, allow for faster adjustment of the output voltage and, therefore, both faster adjustment of the ion energy distribution in the plasma and more fine-tuning of the composite ion energy distribution in the plasma, which includes the sum of the individual ion energy distributions in the plasma.

[0123] The time scale over which the active voltage drop control circuit 1201 adjusts the voltage on the voltage drop capacitor 486 may be less than 2 pulses, 20 pulses, or 200 pulses, where each pulse may have a positive portion and a negative portion that when combined last 100 nanoseconds, 1 microsecond, 2.5 microseconds, 100 microseconds, or 1 millisecond. The time scale over which the active voltage drop control circuit 1201 adjusts the voltage on the voltage drop capacitor 486 may be considered fast for the typical 100 ms to 1 s time scale over which a DC-DC converter typically operates / regulates voltage.

[0124] By adjusting the voltage across the voltage drop capacitor 486, the active voltage drop control circuit 1201 can, for example, control the ion energy distribution in the plasma and / or control the voltage drop between pulses on the wafer. For example, either or both can be done in real time, such as within about 100 microseconds, 10 microseconds, 5 microseconds, 1 microsecond, 500 nanoseconds, 250 nanoseconds, 100 nanoseconds, etc. There may be advantages to rapidly changing the voltage across the voltage drop capacitor 486 and / or slowly changing the voltage. When it changes slowly, a relatively uniform ion energy distribution function can be achieved pulse by pulse, while when it changes rapidly, a very different ion energy distribution function can be achieved pulse by pulse. Whether the voltage across the chuck capacitance (e.g., capacitor 12) changes slowly or rapidly, the accumulated ion energy distribution function may be the same. However, by rapidly changing the voltage across the voltage drop capacitor 486, a completely new and / or different cumulative ion energy distribution function can be achieved than the ion energy distribution function of any single pulse.

[0125] Fig.13 The waveforms of a series of pulses generated by the high voltage pulse power supply and plasma system 1200 are shown. Fig.14A A zoomed-in view of two pulses is shown, Fig. 14B shows the various switches used to generate Fig.13 and 14A Various control waveforms of the waveform shown in .

[0126] For example, output waveform 1305 is a waveform measured at point 134, and wafer waveform 1310 is a corresponding waveform measured at point 135. Output waveform 1305 shows the voltage at capacitor 12. Wafer waveform 1310 shows the voltage on the wafer in the plasma chamber. Control waveform 1420 shows the switching logic of SIG±2, which turns on and off switch module 162 and switch module 164, which produce positive pulse portion 1305 when they are turned off. Control waveform 1415 shows the switching logic of SIG±1, which turns on and off switch module 161 and switch module 163, thereby producing negative pulse portion 1315. Energy recovery waveform 1425 shows the switching logic of SIG±3, which turns on and off ER switch 1215 and ER switch 1217, and energy recovery waveform 1430 shows the switching logic of SIG±4, which turns on and off ER switch 1216 and ER switch 1218.

[0127] The positive pulse portions in waveforms 1305 and 1310 correspond to control waveform 1415 closing switch 161 and switch 163, and control waveform 1420 opening switch 162 and switch 164. The peak and minimum voltage of the positive and negative pulse portions in waveforms 1305 and 1310 may be proportional to the duration of either or both of the on-time of waveform 1425 and / or the on-time of waveform 1430. The duration of the on-time of waveforms 1425 and 1430 may be used to set the voltage on voltage drop capacitor 486. Changing the duration of the on-time of waveforms 1425 and 1430 may be used to change the voltage on voltage drop capacitor 486.

[0128] Additionally, while the negative pulse portion of the output waveform 1305 has a negative slope or drop, the negative pulse portion of the wafer waveform 1310 is substantially flat. In this example, the output waveform 1305 and the wafer waveform 1310 may be created by the plasma system 1200, for example, using a 600V charging voltage from a DC power supply having a 450ns positive pulse width and a 1950ns negative pulse width.

[0129] Fig.13 , Fig.14A and Fig. 14BThe waveforms shown are created using a drop capacitor having a capacitance of less than about 10 μF. For example, the transformer 1201 can have a lower turns ratio, such as a 3:1 or 2:1 turns ratio, or the turns ratio can be set higher, about 10:1 or 40:1. The specific value of the selected turns ratio will partially set the ripple in the current flowing through the energy recovery circuit, and the rate at which the active drop control circuit 1201 can adjust the voltage on the drop capacitor 486. The higher the turns ratio is set, the greater the ripple in the current, and the faster the active drop control circuit 1201 can adjust the voltage on the drop capacitor 486. The switching frequency of the switching modules 1215, 1216, 1217, 1218 can be about 200kHz. The operating frequency between about 1kHz and about 10MHz can be selected. As another example, each switch of the switch modules 1215, 1216, 1217, 1218 may be closed for approximately 1.98 μs, and / or have a duty cycle of approximately 79.2%. The selected duty cycle may vary between 0% and 100%, which allows the active voltage drop control circuit 1201 to recover anywhere from its minimum energy to its maximum energy. The active voltage drop control circuit 1201 may be any form of DC-DC converter.

[0130] Fig.12 A full bridge topology is shown. Many other DC-DC converter topologies are also possible. The DC-DC converter topology can be designed to allow the voltage on the voltage drop capacitor 486 to be adjusted quickly, such as in less than 100 microseconds, 10 microseconds, or 1 microsecond. It can also allow the voltage on the voltage drop capacitor 486 to be adjusted very slowly, such as greater than 1 second, 1000 seconds, or 1 day. Standard operation of the active voltage drop control circuit 1201 can allow the voltage across the voltage drop capacitor 486 to draw any waveform desired on any time scale between very fast and very slow. Some plasma processes may require rapid voltage adjustments, while other plasma processes may require slow adjustments to plasma conditions over hours to days.

[0131] For example, the active voltage drop control circuit 1201 can allow operation under a certain range of wafer voltages without changing the input charging voltage. For example, by changing the positive and negative pulse widths of the switch modules 1215, 1216, 1217, 1218 and / or the duty cycle of the switch modules 1215, 1216, 1217, 1218, the duration of the negative wafer voltage time can be increased and / or the output voltage can be increased. Fig.15A A wafer waveform 1510 is shown having a 1 kV wafer voltage generated by the plasma system 1200 with an 85 ns positive pulse, a 2315 ns negative pulse, and a 300 ns energy recovery pulse from the switch modules 1215 , 1216 , 1217 , 1218 . Fig. 15BA wafer waveform 1510 is shown having a 4 kV wafer voltage generated by the plasma system 1200 with a 200 ns positive pulse width, a 2200 ns negative pulse, and a 730 ns energy recovery pulse from the switching modules 1215 , 1216 , 1217 , 1218 .

[0132] Also disclosed the use Fig. 14B The logic represented by the waveform in the Fig.14A For example, at a first time, the process may include closing a first switch module (e.g., switch module 162 and / or switch module 164) of the high voltage pulse power supply 705 and opening a second switch module (e.g., switch module 161 and / or switch module 163) to generate a positive pulse portion 211 of the first high voltage pulse 1305. The positive pulse portion may have an amplitude greater than about 1 kV, for example.

[0133] At about the first time or shortly thereafter, the plasma may include closing a third switch module (e.g., switch module 1216 and / or switch module 1218) of the energy recovery circuit 2101 and opening a fourth switch module (e.g., switch module 1215 and / or switch module 1217) of the energy recovery circuit 2101.

[0134] At a second time after the first time, the process may, for example, include opening a first switch module (e.g., switch module 162 and / or switch module 164) and closing a second switch module (e.g., switch module 161 and / or switch module 163) to generate a negative pulse portion 212 of the first high voltage pulse.

[0135] At a third time after the second time, the process may, for example, include opening a third switching module.

[0136] At a fourth time after the third time, the process may include, for example, closing the first switch module and opening the second switch module to generate another positive pulse portion of the second high voltage pulse, the positive pulse portion having an amplitude greater than about 1 kV.

[0137] At about the fourth time or shortly thereafter, the process may include, for example, closing the fourth switching module at about the fourth time.

[0138] At a fifth time after the fourth time, the plasma may include, for example, turning on the first switch module and turning off the second switch module to generate a negative pulse portion of the second high voltage pulse.

[0139] Fig.16AAn output waveform 1600 at point 134 and a wafer waveform 1610 at point 135 in an example circuit of a high voltage pulse power supply and plasma system 1200 are shown. In this example, the output waveform 1600 and the wafer waveform 1610 have four different voltage states (e.g., a first state 1605, a second state 1610, a third state 1615, and a fourth state 1620) that are controlled by changing the pulse width and / or duty cycle of the switch in the active voltage drop control circuit 1201 and / or the pulse width of the pulse generated by the power supply 705 and / or the pulse width of the switch in the driving energy recovery circuit. The energy recovery control waveform 1625 controls the switching logic of SIG±3, which turns on and off the ER switch 1215 and the ER switch 1217, and the energy recovery waveform 1630 shows the switching logic of SIG±4, which turns on and off the ER switch 1216 and the ER switch 1218, where ER is an abbreviation for energy recovery.

[0140] The first state 1605 has a duration of about 22.5 μs and a negative voltage of about -10 kV, for example. For example, the first state 1605 can be generated by a 450 ns positive pulse width (+PW) and a 1950 ns negative pulse width (-PW) from the power supply 705 and a symmetrical 1980 ns pulse width of about 200 kHz from the active voltage drop control circuit 1201.

[0141] The second state 1610 has a duration of about 22.5 μs and a negative voltage of about −7.5 kV, for example. The second state 1610 can be generated by a 320 ns positive pulse width (+PW) and a 2080 ns negative pulse width (−PW) from the power supply 705 and a symmetrical 1200 ns pulse width of about 200 kHz from the active voltage drop control circuit 1201.

[0142] The third state 1615 has a duration of about 22.5 μs and a negative voltage of about -5 kV, for example. The third state 1615 can be generated by a 215 ns positive pulse width (+PW) and a 2185 ns negative pulse width (-PW) from the power supply 705 and a symmetrical 1020 ns pulse width of about 200 kHz from the active voltage drop control circuit 1201.

[0143] The fourth state 1620 has a duration of about 22.5 μs and a negative voltage of about −2.5 kV, for example. The fourth state 1620 can be generated by a 115 ns positive pulse width (+PW) and a 2285 ns negative pulse width (−PW) from the power supply 705 and a symmetrical 900 ns pulse width of about 200 kHz from the active voltage drop control circuit 1201.

[0144] Various other voltage states of different durations and voltages may be created by varying the pulse width and / or duty cycle of the switches in active voltage drop control circuit 1201 and / or the pulse width of the pulses produced by power supply 705. DC power supply 151 may also be regulated to create various voltage states.

[0145] Fig.17A Shows Fig.16A , which shows two pulses within the first state 1605 at approximately 20 μs, as well as the control waveform 1415 , the control waveform 1420 , the energy recovery waveform 1425 , and the energy recovery waveform 1430 .

[0146] Fig. 17B Shows Fig.16A , which shows two pulses within the second state 1610 at approximately 40 μs, as well as the control waveform 1415 , the control waveform 1420 , the energy recovery waveform 1425 , and the energy recovery waveform 1430 .

[0147] Fig. 17C Shows Fig.16A , which shows two pulses within the third state 1615 at approximately 60 μs, as well as the control waveform 1415 , the control waveform 1420 , the energy recovery waveform 1425 , and the energy recovery waveform 1430 .

[0148] Fig.17D Shows Fig.16A , which shows two pulses within fourth state 1620 at approximately 80 μs, as well as control waveform 1415 , control waveform 1420 , energy recovery waveform 1425 , and energy recovery waveform 1430 .

[0149] The timing of all control waveforms can be continuously adjusted within all relevant or required time ranges to create the desired output waveform. The timing accuracy of the waveform adjustment may be less than 1 second, 1 millisecond, 1 microsecond, 1 nanosecond or less to create the desired waveform. A specific waveform or pattern of waveforms is usually selected to optimize a specific plasma process, such as increasing the rate of plasma etching, controlling the width of etching features, controlling the aspect ratio of etching features, controlling the mask etching rate, etc. The waveform can be adjusted to control a variety of plasma processes and features. By adjusting the output waveform, the generated ion energy distribution function can be adjusted. The voltage across the voltage drop capacitor 486 and all switch timings can be adjusted to adjust the output waveform, output current, resulting ion energy distribution function and any number of specific plasma and / or etching features. The present invention particularly allows the adjustment of plasma and etching parameters, such as ion energy distribution functions, within a wide and generally continuous operating space. It can achieve this in a steady state manner, where all pulses have a specific ion energy distribution function, or by modulating the output pulses to create a polymer waveform with a specific polymer ion energy distribution function. In any particular etching process, it may be advantageous to continuously optimize the ion energy distribution function throughout the etching process.

[0150] Fig.18 Shown with a combination Fig. 17B Ion energy distribution function (IEDF) of ions within the plasma chamber 106 of the pulsed and configured plasma system 1200 is described.

[0151] Fig.19 Shown with a combination Fig.17A Ion energy distribution of ions within the plasma chamber 106 of the pulsed and configured plasma system 1200 is described.

[0152] Fig. 20A Shows Fig.19 The low-end energy distribution function shown, Fig. 20B Shows Fig.19 The high end energy distribution function is shown. The plasma system 1200 can produce a substantially flat ion energy distribution for various ion energies, which can result in the wafer voltage remaining nearly constant over a longer period of time.

[0153] Fig.21 2 is a circuit diagram of a high voltage pulse power supply and a plasma system 2100 having a voltage drop control circuit 2150 and an energy control circuit 2101. The voltage drop control circuit 2150 includes a diode 2140 connected in series with an inductor 2145. A forward pulse from the secondary side of the transformer 145 reaches the plasma chamber 106 through the diode 2140 and the inductor 2145. Fig.21The case where the voltage drop control element and energy recovery element are placed on the secondary of the transformer is shown. In general, the voltage drop control element and active voltage drop control circuit 1201 can be placed on the primary side of the transformer or on the secondary side of the transformer. Although the specific values ​​used are scaled by the turns ratio of the transformer, the overall function of the elements is the same, with inductors getting larger by the square of the turns ratio and capacitors getting smaller by the square of the turns ratio.

[0154] The series combination of the voltage drop inductor 2120 and the voltage drop capacitor 2130 can be arranged in parallel or across the diode 2140 and / or the inductor 2145. The voltage drop control circuit 2101 controls the voltage ramp on the transformer 145 so that the peak voltage is reached at the later stage of the pulse. The voltage drop inductor 2120 is energized during the negative voltage portion of the bipolar pulse, and once the full charge voltage appears across the inductor 2145 or the plasma chamber 106, an equilibrium is reached where energy is extracted from the voltage drop inductor 2120 at a rate approximately equal to the energy obtained during the positive pulse. During the positive pulse of the bipolar pulse, current flows from the secondary side of the transformer 145 through the diode 2140 and the inductor 2145 to the plasma chamber 106.

[0155] Capacitor 2130 may also be a resistor or an inductor. If it is a capacitor, it may be coupled with an active energy recovery circuit that adjusts the voltage across capacitor 2130 to select the desired output voltage waveform.

[0156] The energy compensation circuit 2101 is coupled to the secondary side of the transformer 145 and the energy storage capacitor 156. The energy compensation circuit 2101 includes, for example, an energy recovery diode 2105 and an energy recovery inductor 2110. The energy recovery diode 2105 and the energy recovery inductor 2110 may be coupled to the secondary side of the transformer 145 via a diode 2115 and a voltage drop control circuit. The inductor 2105 may have a value greater than 1 μH, 10 μH, 100 μH, or 10 mH.

[0157] Fig. 22 Ion energy distribution of ions within the plasma chamber 106 of the plasma system 2100 (or any plasma system disclosed herein) is shown.

[0158] Fig.23A Shows Fig. 22 The low end of the ion energy distribution shown in Fig. 23B Shows Fig. 22. The plasma system 2100 (or any plasma system disclosed herein) can produce an ion energy distribution that is substantially flat for a variety of ion energies (e.g., substantially flat for most ion energies) and peaks in a narrow band of ion energies, which can result in the wafer voltage remaining nearly constant for a long time. By adjusting various voltage drop control and energy recovery elements, any number of potential ion energy distribution functions can be created, and specific elements can be adjusted in real time to maintain specific plasma parameters, or to scan or control various plasma parameter ranges.

[0159] Fig.24 is a circuit diagram of a high voltage pulse power supply and plasma system 2400 having an active voltage drop control circuit 2401. The high voltage pulse power supply and plasma system 2400 includes a high voltage pulse power supply 105 coupled to the active voltage drop control circuit 2401 and a plasma chamber 106. The active voltage drop control circuit can be operated in a manner equivalent to the operation of the voltage drop control and active energy recovery circuit described above to produce various output waveforms and various ion energy distribution functions. Fig.24 is another instance of this creation.

[0160] The active voltage drop control circuit 2401 can be coupled to the voltage drop inductor 187 on the primary side of the transformer 145, for example. The active voltage drop control circuit 2401 can add charge to and / or remove charge from the voltage drop capacitor 486. When the switch 2408 is closed and the switch 2410 is open, the charge stored in the voltage drop capacitor 486 can be dissipated into the resistor 2406. The resistor 2406 can have a resistance of, for example, approximately 0.1 ohms, 3 ohms, or 367 ohms.

[0161] When switch 2408 is open and switch 2410 is closed, voltage drop capacitor 486 may be charged from voltage source 2412 through inductor 2404. Voltage source 2412 may, for example, have a voltage of approximately 0 V, 100 V, 500 V, or 5000 V. Voltage source 2412 may, for example, provide a voltage that is always within approximately 10 V, 300 V, or 5000 V of DC power source 150 and / or DC power source 151.

[0162] Fig.25 25 is a flow chart of an example process 2500 for controlling ion energy distribution on a wafer. In block 2505, a plurality of high voltage pulses (eg, a train of pulses) are introduced into a plasma by a high voltage pulse generator. The process 2500 may be applicable to the plasma system 2400, the plasma system 2100, and / or the plasma system 1200.

[0163] At block 2510, the ion energy distribution on the wafer may be measured, estimated, or calculated. The ion energy distribution on the wafer may be estimated by measuring the voltage of the pulse power supply, the voltage of capacitor 12, the current of the pulse power supply, and / or the plasma density within the chamber.

[0164] In block 2515, it may be determined whether the ion energy distribution (if any) on the wafer is within tolerance. If so, the process 2500 may return to block 2505. If not, the process 2505 may proceed to block 2520.

[0165] At block 2520, ion energy distribution adjustments may be determined based on the measured ion energy distribution and / or the prescribed or desired ion energy distribution.

[0166] At block 2525 , the duty cycle and / or pulse width (open / close duration) of the energy recovery switch may be adjusted. The process 2500 may then return to block 2505 .

[0167] Many other controlled plasmas of the system can be envisioned. Parameters that can be measured and / or adjusted using some form of real-time feedback and control include all aspects of the output voltage and current waveforms, any and / or all switch timings, various component values, ion energy distribution functions, and any number of plasma and / or etching parameters. For example, the voltage across the voltage drop capacitor 720 and / or the voltage drop capacitor 725 can be controlled to maintain a specific etching rate, aspect ratio, mask erosion rate, and / or feature size. For example, the output voltage waveform can be monitored and set in real time to maintain a specific ion energy distribution function, or a set of specific ion energy distribution functions can be plotted / scanned. The selected ion energy distribution function can be selected to optimize one or more specific etching parameters, such as etching rate, aspect ratio, and / or feature size. For example, the voltage drop rate can be changed to control the mask erosion rate.

[0168] Fig.26 is an illustration of an example waveform with two ideal pulse trains: a first pulse train 2605 and a second pulse train 2606. A single pulse train may include multiple pulses 2610. The pulse train duration is the time period when the pulse train is on (Ton) and the pulse train is off (Toff). The pulse width Pwidth is the time period that the pulse lasts. The pulse period Period is the time period when the pulse is on and off. The duty cycle can be expressed as the on time Ton divided by the pulse train duration: The pulse train repetition frequency can be expressed as the inverse of the pulse train period: fburst = 1 / (Ton + Toff). The pulse repetition frequency can be expressed as the inverse of the pulse period: fpulse = 1 / Pperiod.

[0169] A positive waveform has a pulse train where both the lowest voltage V0 and the pulse amplitude V1 are above zero. A negative waveform has a pulse train where both the lowest voltage V0 and the pulse amplitude V1 are below zero. A bipolar waveform has a pulse train where both the lowest voltage V0 and the pulse amplitude V1 are above zero.

[0170] Fig. 27 The computing system 2700 shown can be used to perform any embodiment of the present invention. For example, the computing system 2700 can be used to perform any or all of the process 2500 and / or any feedback and control plasma discussed above. As another example, the computing system 2700 can perform any calculation, identification and / or determination described in this text. The computing system 2700 includes hardware elements that can be electrically coupled via a bus 2705 (or can communicate in other ways as needed). The hardware unit may include one or more processors 2710, including but not limited to one or more general-purpose processors and / or one or more special-purpose processors (e.g., digital signal processing chips, graphics acceleration chips, and / or the like); one or more input devices 2715, which may include but are not limited to a mouse, a keyboard, and / or the like; and one or more output devices 2720, which may include but are not limited to a display device, a printer, and / or the like.

[0171] The computing system 2700 may also include (and / or communicate with) one or more storage devices 2725, which may include, but are not limited to, local and / or network accessible memory, and / or may include, but are not limited to, disk drives, drive arrays, optical storage devices, solid-state storage devices, such as random access memory ("RAM") and / or read-only memory ("ROM"), which may be programmable, flash memory-updatable, and / or the like. The computing system 2700 may also include a communication subsystem 2730, which may include, but are not limited to, a modem, a network card (wireless or wired), an infrared communication device, a wireless communication device and / or a chipset (e.g., a Bluetooth device, an 802.6 device, a Wi-Fi device, a WiMax device, a cellular communication facility, etc.), and / or the like. The communication subsystem 2730 may allow data to be exchanged with a network (e.g., the network described below, to name just one example) and / or any other device described herein. In many embodiments, the computing system 2700 will also include a working memory 2735, which may include a RAM or ROM device as described above.

[0172] The computing system 2700 may also include software elements, shown as currently located in the working memory 2735, including an operating system 2740 and / or other code, such as one or more application programs 2745, which may include the computer program of the present invention, and / or may be designed to implement the method of the present invention as described herein and / or configure the system of the present invention. For example, one or more programs described with respect to the methods discussed above may be implemented as codes and / or instructions executable by a computer (and / or a processor within a computer). A set of these instructions and / or codes may be stored on a computer-readable storage medium, such as the storage device 2725 described above.

[0173] In some cases, the storage medium may be incorporated into or in communication with the computing system 2700. In other embodiments, the storage medium may be separate from the computing system 2700 (e.g., removable media such as a compact disc, etc.), and / or provided in the form of an installation package such that the storage medium can be used to program a general purpose computer using the instructions / code stored thereon. These instructions may be in the form of executable code that can be executed by the computing system 2700, and / or may be in the form of source and / or installable code that, after being compiled and / or installed on the computing system 2700 (e.g., using various commonly available compilers, installers, compression / decompression utilities, etc.), then in the form of executable code.

[0174] The above general description and related optimization / operating space descriptions may be generally applicable in one form or another to all circuits disclosed in the specification or any of the figures. All circuits may operate in a similar manner; for example, a brief positive pulse may reset the system and cancel the charge accumulated on the wafer by the previously flowing ion current; wherein the current in a voltage drop inductor (e.g., voltage drop inductor 187) may set the voltage on the wafer and / or may reduce, eliminate, or reverse any voltage drop; wherein the current may be set by balancing the energy flowing into the voltage drop inductor with the energy flowing out of the voltage drop inductor (e.g., by balancing positive volt-seconds with negative volt-seconds across the inductor); and / or the net energy balance of energy flowing into and out of the voltage drop inductor may be set by an energy recovery circuit, whether the energy recovery circuit is active or passive in nature.

[0175] Unless otherwise specified, the term "substantially" means within 5% or 10% of the stated value or within a manufacturing tolerance. Unless otherwise specified, the term "about" means within 5% or 10% of the stated value or within a manufacturing tolerance.

[0176] The conjunction "or" is inclusive.

[0177] The terms "first", "second", "third" and the like are used to distinguish between various elements and are not used to indicate a particular order of these elements, unless otherwise specified or an order is explicitly described or required.

[0178] Numerous specific details are set forth to provide a thorough understanding of the claimed subject matter. However, it will be understood by those skilled in the art that the claimed subject matter may be practiced without these specific details. In other cases, methods, devices, or systems known to those skilled in the art are not described in detail in order to avoid obscuring the claimed subject matter.

[0179] Some parts are presented in the form of algorithms or symbolic representations of operations on data bits or binary digital signals stored in a computing system memory (e.g., computer memory). These algorithmic descriptions or representations are examples of techniques used by those of ordinary skill in the data processing arts to convey the substance of their work to others skilled in the art. An algorithm is a self-consistent series of operations or similar processes that achieve a desired result. In this case, the operations or processes involve physical manipulation of physical quantities. Typically, although not necessarily, these quantities may take the form of electrical or magnetic signals that can be stored, transferred, combined, compared, or otherwise manipulated. It turns out that it is sometimes convenient to refer to these signals as bits, data, values, elements, symbols, characters, terms, numbers, numerical values, etc., primarily for reasons of common usage. It should be understood, however, that all of these and similar terms are associated with the appropriate physical quantities and are merely convenient labels. Unless expressly stated otherwise, it should be understood that terms such as "processing," "computing," "determining," and "identifying" are used throughout the discussion of this specification to refer to the actions or plasma of a computing device (such as one or more computers or similar electronic computing devices) that operates or transforms data represented as physical electronic or magnetic quantities in the memory, registers, or other information storage devices, transmission devices, or display devices of a computing platform.

[0180] The one or more systems discussed are not limited to any particular hardware architecture or configuration. The computing device may include any suitable arrangement of components to provide a result based on one or more inputs. Suitable computing devices include multi-purpose microprocessor-based computer systems that access stored software that can program or configure the computing system from a general-purpose computing device to a special-purpose computing device that implements one or more embodiments of the present subject matter. Any suitable programming, scripting, or other type of language or combination of languages ​​may be used to implement the teachings contained in the software for programming or configuring the computing device.

[0181] Embodiments of the disclosed method may be performed in the operation of such a computing device. The order of the blocks presented in the above examples may be changed, for example, they may be reordered, combined and / or decomposed into sub-blocks. Certain blocks or processes may be performed in parallel.

[0182] The use of "suitable for" or "configured to" is intended to express open and inclusive language and does not exclude devices adapted or configured to perform additional tasks or steps. In addition, the use of "based on" is intended to be open and inclusive, as plasmas, steps, calculations, or other actions based on one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated. The included headings, lists, and numbers are for ease of explanation only and are not intended to be limiting.

[0183] Although the subject matter has been described in detail with respect to specific embodiments, it should be understood that those skilled in the art can easily make changes, variations and equivalents to these embodiments after understanding the foregoing. Therefore, it should be understood that the present disclosure is provided for the purpose of illustration rather than limitation, and does not exclude modifications, variations and / or additions to the subject matter that are obvious to those skilled in the art.

Claims

1. A high voltage pulse power supply system, comprising: DC power supply; a switching circuit electrically coupled to the DC power source, the switching circuit comprising a plurality of switch modules arranged in a full-bridge configuration, the switching circuit generating a plurality of pulses having a positive pulse portion, a negative pulse portion, and an amplitude greater than about 10 kV; Transformer, including: Transformer core; a primary winding wound on the transformer core; and A secondary winding wound on the transformer core; A voltage drop control circuit, the voltage drop control circuit is electrically coupled to the switch circuit and the primary winding, the voltage drop control circuit comprising: a voltage drop diode electrically coupled in series between the switching circuit and the primary winding to allow the negative pulse portion of the plurality of pulses to pass from the switching circuit to the primary winding of the transformer; and a voltage-drop inductor and a voltage-drop element arranged in series across the voltage-drop diode, allowing the negative pulse portion of the plurality of pulses to pass from the switching circuit to the primary winding of the transformer and storing energy from the negative pulse portion of the plurality of pulses; and An output electrically coupled to the secondary winding outputs the plurality of pulses having a substantially flat negative pulse portion. 2 . The high-voltage pulse power supply according to claim 1 , wherein the voltage drop element comprises a capacitor or a resistor. 3 . The high-voltage pulse power supply according to claim 1 , wherein the inductance of the voltage drop inductor is between about 1 μH and about 10 mH.

4. The high-voltage pulse power supply according to claim 1 further includes an energy recovery circuit electrically coupled to the voltage drop element and the high-voltage power supply, and includes one or more switch modules that are opened and closed to add charge to or remove charge from the voltage drop element.

5. The high voltage pulse power supply of claim 1 , wherein the high voltage pulse power supply is coupled to a plasma chamber having a plasma, and wherein the output produces an ion energy distribution that is substantially flat for most ion energies and peaks in a narrow band of ion energies. 6 . The high-voltage pulse power supply according to claim 4 , wherein the one or more switch modules of the energy recovery circuit are arranged in a full-bridge configuration or a half-bridge configuration.

7. The high-voltage pulse power supply according to claim 4, wherein the energy recovery circuit comprises a diode and an inductor arranged in series between the voltage drop element and the high-voltage power supply.

8. The high-voltage pulse power supply according to claim 4, wherein the energy recovery circuit comprises a DC-DC converter.

9. The high voltage pulse power supply of claim 1 further comprising a plasma chamber having one or more electrodes electrically coupled to the output, wherein the plurality of pulses produces an ion energy distribution within the plasma that is substantially flat for a majority of ion energies and peaks in a narrow band of ion energies.

10. A plasma system comprising: DC power supply; a switching circuit electrically coupled to the DC power source, the switching circuit comprising a plurality of switch modules arranged in a full-bridge configuration, the switching circuit generating a plurality of pulses having a positive pulse portion, a negative pulse portion, and an amplitude greater than about 10 kV; Transformer, including: Transformer core; a primary winding wound on the transformer core; and A secondary winding wound on the transformer core; A voltage drop control circuit, the voltage drop control circuit is electrically coupled to the switch circuit and the primary winding, the voltage drop control circuit comprising: a voltage drop diode electrically coupled in series between the switching circuit and the primary winding to allow the negative pulse portion of the plurality of pulses to pass from the switching circuit to the primary winding of the transformer; and a voltage-drop inductor and a voltage-drop capacitor arranged in series across the voltage-drop diode, allowing the negative pulse portion of the plurality of pulses to pass from the switching circuit to the primary winding of the transformer and storing energy from the negative pulse portion of the plurality of pulses; an energy recovery circuit electrically coupled to the voltage drop capacitor and the high voltage power supply, the energy recovery circuit comprising one or more switch modules that open and close to add charge to or remove charge from the voltage drop capacitor; and A plasma chamber having one or more electrodes electrically coupled to the secondary winding, wherein the plurality of pulses produces an ion energy distribution within the plasma that is substantially flat for a majority of ion energies and peaks in a narrow band of ion energies.

11. The high voltage pulse power supply according to claim 10, wherein the plurality of pulses include a substantially flat negative pulse portion. 12 . The high voltage pulse power supply according to claim 10 , wherein the inductance of the voltage drop inductor is between about 1 μH and about 10 mH.

13. The high voltage pulse power supply according to claim 10, wherein the energy recovery circuit comprises a DC-DC converter.

14. The high-voltage pulse power supply according to claim 10, wherein the energy recovery circuit comprises a transformer located between the plurality of switch modules and the DC-DC converter. 15 . The high-voltage pulse power supply according to claim 10 , wherein the energy recovery circuit comprises an energy recovery inductor and a diode connected in series between the high-voltage power supply and the one or more switch modules. 16 . The high-voltage pulse power supply according to claim 10 , wherein the one or more switch modules of the energy recovery circuit are arranged in a full-bridge configuration or a half-bridge configuration.

17. A high voltage pulse power supply system, comprising: DC power supply; a switching circuit electrically coupled to the DC power source, the switching circuit comprising a plurality of switch modules arranged in a full-bridge configuration, the switching circuit generating a plurality of pulses having a positive pulse portion, a negative pulse portion, and an amplitude greater than about 10 kV; Transformer, including: Transformer core; a primary winding wound on the transformer core; and A secondary winding wound on the transformer core; A voltage drop control circuit, the voltage drop control circuit is electrically coupled to the switch circuit and the primary winding, the voltage drop control circuit comprising: a voltage drop diode electrically coupled in series between the switching circuit and the primary winding to allow the negative pulse portion of the plurality of pulses to pass from the switching circuit to the primary winding of the transformer; and a voltage-drop inductor and a voltage-drop capacitor arranged in series across the voltage-drop diode, which allow the negative pulse portion of the plurality of pulses to pass from the switching circuit to the primary winding of the transformer and store energy from the negative pulse portion of the plurality of pulses; an energy recovery circuit electrically coupled to the voltage drop capacitor, the energy recovery circuit comprising a plurality of switch modules and a DC-DC converter arranged in a half-bridge or full-bridge, the plurality of switch modules being turned on and off to add charge to or remove charge from the voltage drop capacitor; and An output electrically coupled to the secondary winding outputs the plurality of pulses having a substantially flat negative pulse portion.

18. The high voltage pulse power supply of claim 17, further comprising a plasma chamber having one or more electrodes electrically coupled to the output, wherein the plurality of pulses produces an ion energy distribution within the plasma that is substantially flat for most ion energies and peaks in a narrow band of ion energies.

19. The high voltage pulse power supply according to claim 17, wherein the inductance of the voltage drop inductor is between about 1 μH and about 10 mH.

20. The high-voltage pulse power supply according to claim 17, wherein the energy recovery circuit comprises an energy recovery inductor and a diode arranged in series between the high-voltage power supply and the DC-DC converter.

21. A method comprising: Generating a first high-voltage pulse train into a plasma chamber having plasma, wherein the high-voltage pulse train has a plurality of high-voltage pulses, the high-voltage pulses have a first duty cycle, and each of the plurality of high-voltage pulses has a pulse amplitude greater than 1 kV and a first pulse width; estimating an ion energy distribution function within the plasma; comparing the estimated ion energy distribution function to a desired ion energy distribution function; and If the estimated ion energy function differs from the desired ion energy distribution function by more than a threshold: determining either or both of a second duty cycle and a second pulse width based on a difference between the estimated ion energy function and a desired ion energy distribution function; as well as A second high-voltage pulse train is generated into a plasma chamber having plasma, wherein the high-voltage pulse train has a plurality of high-voltage pulses having a second duty cycle, and each of the plurality of high-voltage pulses has a pulse amplitude greater than 1 kV and a second pulse width.

22. A method comprising: Turning off the first switch module of the high-voltage pulse power supply and turning on the second switch module to generate a positive pulse portion of a first high-voltage pulse at a first time, wherein the amplitude of the positive pulse portion is greater than about 1 kV; Closing the third switch module of the energy recovery circuit at the first time and opening the fourth switch module; Opening the first switch module and closing the second switch module to generate a negative pulse portion of the first high voltage pulse at a second time, wherein the second time is after the first time; Turning on the third switch module at a third time, wherein the third time is after the second time; closing the first switch module and opening the second switch module to generate a positive pulse portion of a second high voltage pulse, the positive pulse portion having a magnitude greater than about 1 kV at a fourth time, wherein the fourth time is after the third time; Closing the fourth switch module at about the fourth time; as well as The first switch module is opened and the second switch module is closed to generate a negative pulse portion of the second high-voltage pulse at a fifth time, wherein the fifth time is located after the fourth time.

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