Hybrid Frequency Plasma Source

Abstract

The plasma system includes a first matchless plasma source (MPS) generating a first sinusoidal waveform having a first frequency. The plasma system includes a first filter coupled to the first MPS to filter a second frequency. The plasma system further includes a first capacitive circuit coupled to the first filter to balance between a reactance of the first filter and a radio frequency (RF) coil and provide a first RF signal to the point. The plasma system includes a second MPS generating a second sinusoidal waveform having a second frequency. The plasma system includes a second filter coupled to the second MPS to filter the first frequency. The plasma system includes a second capacitive circuit coupled to the second filter to balance a reactance of the second filter and a reactance of the RF coil and further provide a second RF signal to the point.

Description

[Technical field]

[0001] The present embodiment relates to a hybrid frequency plasma source. [Background technology]

[0002] Plasma systems are used to perform various operations on wafers. The plasma system includes a radio frequency (RF) generator, an RF matcher, and a plasma chamber. The RF generator is coupled to the RF matcher via an RF cable, which is coupled to the plasma chamber. RF power is provided to the plasma chamber in which the wafer is processed via the RF cable and the RF matcher. Also, one or more gases are provided to the plasma chamber, which generates or sustains a plasma in the plasma chamber upon receiving the RF power. When RF power is provided, a plasma may not be struck in the plasma chamber, or arcing may occur in the plasma chamber.

[0003] It is against this background that the embodiments described in this disclosure arise. Summary of the Invention

[0004] The embodiments of the present disclosure provide a system, an apparatus, a method, and a computer program for providing a hybrid frequency plasma source. It should be understood that the embodiments can be implemented in numerous ways, such as, for example, a process, or an apparatus, or a system, or hardware, or a method, or a computer readable medium. Several embodiments are described below.

[0005] Each inductively coupled plasma (ICP) coil in a plasma chamber is driven at any given moment by one radio frequency (RF) generator at one RF frequency. The choice of RF frequency is limited by several factors. The coil voltage of the ICP coil increases with increasing RF frequency, which can cause arcing in the ICP coil or sputtering on the dielectric window of the plasma chamber. Arcing or sputtering is caused by ions accelerated by capacitively coupled RF power from the coil. On the other hand, at lower radio frequencies, the effect of coupling becomes smaller, especially at lower plasma densities. Also, with lower voltages in the ICP coil, it is more difficult for the RF generator to chemically transform the neutral gas to strike a plasma.

[0006] In one embodiment, a dual frequency ICP source is presented that operates at two radio frequencies. For example, two independent RF sources (e.g., RF generators, or matchless plasma sources (MPS)) tuned to two widely separated RF frequencies are used to simultaneously power the ICP coil through a single power feed. Illustratively, two MPSs (e.g., a low frequency MPS and a high frequency MPS) are used to drive the same ICP coil. The two MPSs operate at two separate frequencies, a low frequency and a high frequency. As an example, the low frequency is in the range of 1.8 megahertz (MHz) to 2.2 MHz, and the high frequency is in the range of 12.35 MHz to 13.65 MHz. As another example, the low frequency is in the range of 400 kilohertz (kHz) to 2 MHz, and the high frequency is in the range of 12 MHz to 27 MHz. The corresponding output of each MPS is attached to a filter circuit for isolation. Each filter circuit is also coupled to a corresponding capacitor to cancel the reactance remaining from the ICP coil and the filter circuit, such that a series resonance at low frequency and a series resonance at high frequency are presented to the low frequency MPS and the high frequency MPS, respectively. Each capacitor can be either a fixed value capacitor or a variable value capacitor. For example, the network between each of the MPS and the ICP coil includes fixed elements (e.g., fixed capacitors and fixed inductors) and no variable elements, thereby not requiring active control of the network during operation.

[0007] In an embodiment, a low pass filter and a high pass filter may be coupled to the outputs of the low frequency MPS and the high frequency MPS, respectively.

[0008] In one embodiment, a bandpass filter can be coupled to the output of either of the two MPSs. For example, a series resonant circuit including a series circuit of a capacitor and an inductor can be used as a bandpass filter to provide suitable isolation from low or high frequencies.

[0009] In one embodiment, a first bandpass filter is coupled to the output of the low frequency MPS and a second bandpass filter is coupled to the output of the high frequency MPS.

[0010] In one embodiment, two 50 Ω RF generators operate at separate RF frequencies to energize the same ICP coil. The two RF generators employed are capable of outputting RF tuned to a low frequency band of 400 kHz to 2 MHz and a high frequency band of 12 MHz to 27 MHz, respectively. The two RF generators provide inputs to a dual frequency impedance matching network, which transforms the impedance of the ICP coil at its output port to 50 ohms and presents it to the two RF generators.

[0011] In one embodiment, the dual frequency impedance matching network includes one or more isolation filter circuits. The dual frequency impedance matching network includes two sub-networks, one for transmitting low frequencies and the other for transmitting high frequencies. The isolation filter circuits can be placed on either the input side or the output side, or both the input side and the output side, of each of the two sub-networks. Each of the two sub-networks transforms the load impedance of the corresponding low frequency and high frequency to 50 Ω. For example, the isolation filter circuit is placed on the output side to minimize the change seen in one sub-network when the circuit elements on the other sub-network are changed. Examples of each sub-network include an L-network and a T-network.

[0012] In one embodiment, an MPS and a 50 ohm RF generator are used to energize the same ICP coil, with the MPS operating at a different frequency than the 50 ohm RF generator.

[0013] In one embodiment, the low and high frequencies are independent of each other, allowing a variety of pulsed operations to be achieved. For example, one frequency can be pulsed and the other a continuous wave (cw) output. In another example, both the low and high frequencies can be pulsed with different pulse output frequencies and duty cycles.

[0014] In one embodiment, a current splitting circuit is provided for use with a dual coil plasma system (e.g., a plasma system having two transformer-coupled plasma (TCP) coils). The current splitting circuit is added to the output of a first MPS at one frequency (e.g., low frequency or high frequency), with the same MPS driving both TCP coils. In this embodiment, a second MPS can be added to the first of the TCP coils. An additional filter can be added such that the frequency of the second MPS is blocked to the second of the TCP coils.

[0015] In one embodiment, a hybrid frequency plasma system is provided. The hybrid frequency plasma system includes a first matchless plasma source that generates a first sinusoidal waveform. The first sinusoidal waveform is generated based on a first square waveform and has a first frequency. The hybrid frequency plasma system includes a first filter coupled to the first matchless plasma source. The first filter filters a second frequency from interfering with the first sinusoidal waveform. The hybrid frequency plasma system further includes a first capacitive circuit coupled to the first filter. The first capacitive circuit outputs a first RF signal by balancing a reactance of the first filter with a reactance of an RF coil of the plasma chamber. The first capacitive circuit provides the first RF signal to a point coupled to the RF coil. The hybrid frequency plasma system includes a second matchless plasma source that generates a second sinusoidal waveform. The second sinusoidal waveform is generated based on a second square waveform and has a second frequency. The hybrid frequency plasma system includes a second filter coupled to the second matchless plasma source. The second filter filters the first frequency from interfering with the second sinusoidal waveform. The hybrid frequency plasma system includes a second capacitive circuit coupled to the second filter. The second capacitive circuit balances a reactance of the second filter with a reactance of the RF coil to output a second RF signal. The second capacitive circuit provides the second RF signal to the point.

[0016] In an embodiment, a hybrid frequency plasma system is provided. The hybrid frequency plasma system includes a matchless plasma source that generates a sinusoidal waveform. The sinusoidal waveform is generated based on a square waveform and has a first frequency. The hybrid frequency plasma system further includes a first filter coupled to the matchless plasma source. The first filter filters a second frequency from interfering in the sinusoidal waveform. The hybrid frequency plasma system includes a capacitive circuit coupled to the first filter. The capacitive circuit balances a reactance of the first filter with a reactance of an RF coil of the plasma chamber to output a first RF signal. The capacitive circuit provides the first RF signal to a point coupled to the RF coil. The hybrid frequency plasma system includes a source RF generator that generates a second RF signal having a second frequency. The hybrid frequency plasma system includes an impedance matching network coupled to the source RF generator. The impedance matching network receives the second RF signal and modifies an impedance of the second RF signal to output a modified RF signal. The impedance matching network includes a second filter that filters the first frequency from interfering with the second RF signal. The impedance matching network provides the modified RF signal to the point.

[0017] In an embodiment, a hybrid frequency plasma system is provided. The hybrid frequency plasma system includes a first matchless plasma source that generates a first sinusoidal waveform. The first sinusoidal waveform is generated based on a first square waveform and has a first frequency. The hybrid frequency plasma system further includes a first filter coupled to the first matchless plasma source. The first filter filters a second frequency from interfering with the first sinusoidal waveform. The hybrid frequency plasma system includes a first capacitive circuit coupled to the first filter. The first capacitive circuit outputs a first RF signal by balancing a reactance of the first filter with a reactance of a first RF coil of the plasma chamber. The first capacitive circuit provides the first RF signal to a point. The hybrid frequency plasma system includes a second matchless plasma source that generates a second sinusoidal waveform. The second sinusoidal waveform is generated based on a second square waveform and has a second frequency. The hybrid frequency plasma system includes a second filter coupled to the second matchless plasma source. The second filter filters the first frequency from interfering with the second sinusoidal waveform. The hybrid frequency plasma system includes a second capacitive circuit coupled to the second filter. The second capacitive circuit outputs a second RF signal balancing a reactance of the second filter, a reactance of the first RF coil, and a reactance of the second RF coil of the plasma chamber. The hybrid frequency plasma system includes a signal splitter coupled to the second capacitive circuit. The signal splitter splits the second RF signal into a third RF signal and a fourth RF signal. The signal splitter also includes a third capacitive circuit and a fourth capacitive circuit. The third capacitive circuit receives the third RF signal and provides a fifth RF signal to the point balancing a reactance of the first RF coil of the plasma chamber and a reactance of the second filter. A fourth capacitive circuit receives the fourth RF signal and provides a sixth RF signal to the second RF coil, balancing the reactance of the second RF coil and the reactance of the second filter.

[0018] Some advantages of the systems and methods described herein include an increased amount of plasma stability. Plasma instabilities occur in different regions of the operating space that spans an ICP coil with a single frequency (such as a low frequency or a high frequency). By having two RF frequencies available on the same ICP coil, the stability window is expanded relative to the combination of the individual stability windows of at least two frequencies. Thus, an unstable radio frequency can be avoided if the other radio frequency is stable. Furthermore, a stability window can be created by applying two frequencies simultaneously.

[0019] Further advantages of the systems and methods described herein include lower coil voltage and smaller window sputtering. Typically, when a lower frequency is applied, the ICP coil voltage is lower. By replacing some of the high frequency power with low frequency power while maintaining the same plasma density, the ICP coil voltage can be lowered below the sputtering threshold of the dielectric window, thereby extending the life of the dielectric window.

[0020] Additional advantages of the systems and methods described herein include rapid plasma ignition. A coil voltage higher than the amount of voltage used to sustain the plasma is applied to strike the plasma. Rapid plasma ignition is achieved by applying a high frequency. A high frequency can be used to strike the plasma upon initial power up, and then power can be partially or completely switched to a lower frequency to sustain the plasma.

[0021] Additional advantages of the systems and methods described herein include increased control over uniformity when processing a substrate and increased control over the amount of tilt with which plasma ions are incident on the substrate. For many process conditions, the plasma density profile is different when two frequencies are applied to the same ICP coil. Having two frequencies available provides an additional knob for tuning etch and tilt uniformity.

[0022] Other aspects will become apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0023] The embodiments are understood by reference to the following description taken in conjunction with the accompanying drawings.

[0024] [Figure 1] FIG. 1 is a diagram of one embodiment of a system to illustrate a hybrid matchless plasma source (MPS).

[0025] [Figure 2A] FIG. 2A is a diagram of one embodiment of a low pass filter.

[0026] [Figure 2B] FIG. 2B is a diagram of one embodiment of a high pass filter.

[0027] [Figure 2C] FIG. 2C is a diagram of one embodiment of a bandpass filter.

[0028] [Figure 2D] FIG. 2D is a diagram of one embodiment of a bandpass filter.

[0029] [Figure 3A] FIG. 3A is a diagram of one embodiment of a plasma system to illustrate the use of low frequency (LF) and high frequency (MPS) in the plasma system.

[0030] [Figure 3B] FIG. 3B is a diagram of one embodiment of a plasma system to illustrate the use of LFMPS and HFMPS when the lower electrode is coupled to ground potential.

[0031] [Figure 4]FIG. 4 is a diagram of one embodiment of a system to illustrate the use of an LF source radio frequency generator (RFG) and an HF source RFG to provide RF power to an RF coil.

[0032] [Figure 5A] FIG. 5A is a diagram of one embodiment of a dual-frequency matching box.

[0033] [Figure 5B] FIG. 5B is a diagram of an embodiment of another dual-frequency matching box.

[0034] [Figure 5C] FIG. 5C is a diagram of yet another embodiment of a dual-frequency matching box.

[0035] [Figure 6A] FIG. 6A is a diagram of one embodiment of a plasma system having LF bias RFG and HF bias RFG to illustrate the use of an LF source RFG and an HF source RFG.

[0036] [Figure 6B] FIG. 6B is a diagram of one embodiment of a system having a plasma chamber with a bottom electrode coupled to ground potential to illustrate the use of an LF source RFG and an HF source RFG.

[0037] [Figure 7A] FIG. 7A is a diagram of one embodiment of a system having an HF source RFG to illustrate the use of an LFMPS.

[0038] [Figure 7B] FIG. 7B is a diagram of an embodiment of a system having an HFMPS to illustrate the use of an LF source RFG.

[0039] [Figure 8A] FIG. 8A is a diagram of one embodiment of a system having LF bias RFG and HF bias RFG to illustrate the use of LF RFG and HF source RFG.

[0040] [Figure 8B] FIG. 8B is a diagram of one embodiment of a system to illustrate the use of an LFMPS and an HF source RFG when the bottom electrode is coupled to ground potential.

[0041] [Figure 8C] FIG. 8C is a diagram of an embodiment of a system having LF Bias RFG and HF Bias RFG to illustrate the use of LF Source RFG and HFMPS.

[0042] [Figure 8D] FIG. 8D is a diagram of one embodiment of a system to illustrate the use of LF sources RFG and HFMPS when the lower electrode is coupled to ground potential.

[0043] [Figure 9A] FIG. 9A is a diagram of one embodiment of a system to provide high frequency to multiple RF coils and to illustrate how low and high frequencies can be provided to an RF coil.

[0044] [Figure 9B] FIG. 9B is a diagram of one embodiment of a system to provide low frequencies to multiple RF coils and to illustrate how low and high frequencies can be provided to an RF coil.

[0045] [Figure 9C] FIG. 9C is a diagram of an embodiment of a plasma system to illustrate a method for filtering low frequencies from being applied to an RF coil.

[0046] [Figure 9D] FIG. 9D is a diagram of an embodiment of a plasma system to illustrate a method for filtering high frequencies from being applied to an RF coil.

[0047] [Figure 10A]FIG. 10A is a diagram of an embodiment of a plasma system to illustrate the use of a signal splitter within the plasma system.

[0048] [Figure 10B] FIG. 10B is a diagram of an embodiment of a plasma system having a plasma chamber with a lower electrode coupled to ground potential to illustrate the use of the signal splitter of FIG. 10A.

[0049] [Figure 10C] FIG. 10C is a diagram of an embodiment of a plasma system to illustrate the use of an alternative signal splitter.

[0050] [Figure 10D] FIG. 10D is a diagram of one embodiment of a plasma system having a plasma chamber with a lower electrode coupled to ground potential to illustrate the use of the signal splitter of FIG. 10C.

[0051] [Figure 11A] FIG. 11A is one embodiment of a graph to illustrate a clock signal.

[0052] [Figure 11B] FIG. 11B is one embodiment of a graph to illustrate parameters of an RF signal generated by the LFMPS or LF bias RFG or LF source RFG.

[0053] [Figure 11C] FIG. 11C is one embodiment of a graph to illustrate parameters of an RF signal generated by the HFMPS or HF bias RFG or HF source RFG.

[0054] [Figure 11D] FIG. 11D is one embodiment of a graph to illustrate a low frequency RF signal.

[0055] [Figure 11E]FIG. 11E is one embodiment of a graph to illustrate a high frequency RF signal.

[0056] [Figure 11F] FIG. 11F is an embodiment of a graph of the RF signal of FIG. 11D.

[0057] [Figure 11G] FIG. 11G is one embodiment of a graph to illustrate a pulsed RF signal output that is out of phase with the pulsed RF signal output of FIG. 11F.

[0058] [Figure 11H] FIG. 11H is an embodiment of a graph of the RF signal of FIG. 11D.

[0059] [Figure 11I] FIG. 11I is one embodiment of a graph to illustrate that the pulse output frequency of the parameter of the RF signal of FIG. 11F is different from the pulse output frequency of the parameter of the RF signal.

[0060] [Figure 12A-1] FIG. 12A-1 is a diagram of one embodiment of the system to illustrate details of the MPS.

[0061] [Figure 12A-2] FIG. 12A-2 is a diagram of one embodiment of a system to illustrate further details of the inputs and outputs of the MPS of FIG. 12A-1.

[0062] [Figure 12B] FIG. 12B is a diagram of one embodiment of the system to illustrate details of the RF generator.

[0063] [Figure 13] FIG. 13 is a diagram of one embodiment of a system to illustrate control of a variable capacitor.

[0064] [Figure 14]FIG. 14 is a diagram of one embodiment of a plasma chamber to illustrate the solenoid coil.

[0065] [Figure 15] FIG. 15 is a diagram of one embodiment of a plasma system to illustrate the use of LFMPS and HFMPS with a substrate support.

[0066] [Figure 16A] FIG. 16A is a diagram of one embodiment of a system to illustrate a master-slave configuration in which the LFMPS is the controlling side and the HFMPS is the controlled side.

[0067] [Figure 16B] FIG. 16B is a diagram of one embodiment of a system to illustrate a master-slave configuration in which the HFMPS is the controlling side and the LFMPS is the controlled side.

[0068] [Figure 16C] FIG. 16C is a diagram of one embodiment of a system to illustrate a master-slave configuration in which the LF source RFG is the controlling side and the HFMPS is the controlled side.

[0069] [Figure 16D] FIG. 16D is a diagram of one embodiment of a system to illustrate a master-slave configuration where the HF source RFG is the controlling side and the LFMPS is the controlled side.

[0070] [Figure 16E] FIG. 16E is a diagram of one embodiment of a system to illustrate a master-slave configuration in which the LFMPS is the controlling side and the HF source RFG is the controlled side.

[0071] [Figure 16F] FIG. 16F is a diagram of one embodiment of a system to illustrate a master-slave configuration in which the HFMPS is the controlling side and the LF source RFG is the controlled side. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0072] In the following embodiments, systems and methods for providing a hybrid frequency plasma source are described. It will be understood that the embodiments may be practiced without some or all of these specific details. In other instances, well-known operations have not been described in detail so as not to unnecessarily obscure the embodiments.

[0073] FIG. 1 is a diagram of an embodiment of a system 100 to illustrate a hybrid matchless plasma source (MPS). The hybrid MPS is a dual frequency MPS. The system 100 includes a low frequency (LF) MPS 102 and a high frequency (HF) MPS 104. The combination of the LFMPS 102 and the HFMPS 104 is a hybrid MPS. The system 100 further includes a first filter 106 and a second filter 108. The system 100 includes a first capacitor 110 and a second capacitor 112. The first capacitor 110 may be referred to herein as a capacitive circuit, and the second capacitor may be referred to herein as a capacitive circuit. By way of example, each capacitor is described herein as a fixed capacitor or a variable capacitor. The system 100 also includes a radio frequency (RF) coil 114. As used herein, an RF coil may be referred to as an inductively coupled plasma (ICP) coil or a transformer coupled plasma (TCP) coil. The RF coil 114 is an example of an upper electrode of the plasma chamber and has one or more turns or windings.

[0074] An example of a low frequency MPS is a matchless plasma source that operates at a low frequency, such as a frequency in the range of 400 kilohertz (kHz) to 2 megahertz (MHz), inclusive, to generate an RF signal having a low frequency. Illustratively, the operating frequency of the low frequency MPS is 400 kHz or 2 MHz. An example of a high frequency MPS is a matchless plasma source that operates at a high frequency, such as a frequency in the range of 12 MHz to 60 MHz, inclusive, to generate an RF signal having a high frequency. Illustratively, the operating frequency of the high frequency MPS is 13.56 MHz or 27 MHz or 60 MHz. An example of a capacitor as used herein is a fixed capacitor or a variable capacitor. Illustratively, the high frequency is greater than the low frequency and is excluded from the low frequency. For example, the value of the high frequency does not match the value of the low frequency. An example of the first filter 106 is a low pass filter or a band pass filter, and an example of the second filter 108 is a high pass filter or a band pass filter.

[0075] The LFMPS 102 is coupled to a first filter 106, which is coupled to a first capacitor 110. Similarly, the HFMPS 104 is coupled to a second filter 108, which is coupled to a second capacitor 112. The capacitors 110 and 112 are coupled to each other at a point 122. An example of the point 122 is a connection, such as a connector, between a first RF connection, a second RF connection, and a third RF connection. The first RF connection is between the first capacitor 110 and the point 122, the second RF connection is between the second capacitor 112 and the point 122, and the third RF connection is between the point 122 and the RF coil 114. Illustratively, the point 122 is a solder between the first, second, and third RF straps. The first RF strap is an example of a first RF connection, the second RF strap is an example of a second RF connection, and the third RF strap is an example of a third RF connection. As another example, the point 122 is a bolt that connects the first, second, and third RF straps. The point 122 is coupled to the end E1 of the RF coil 114 via the RF connection 125. Examples of RF connections used herein include RF cables, RF straps, RF cylinders, RF transmission lines, and combinations of two or more thereof. By way of example, the RF straps are long and flat. By way of further example, the RF straps are rectangular. By way of example, the RF cable has an RF sheath and an RF conductor. The opposite end E2 of the RF coil 114 is coupled to ground potential.

[0076] The LFMPS 102 generates an RF signal 116A and provides the RF signal 116A to a first filter 106. The RF signal 116A is a sinusoidal waveform. For example, the RF signal 116A has the shape of a sinusoidal signal. The first filter 106 passes a low frequency of the RF signal 116A and outputs a filtered signal 118A. For example, the low frequency of the filtered signal 118A is the same as the low frequency of the RF signal 116A.

[0077] The first filter 106 provides the filtered signal 118A to the first capacitor 110. The first capacitor 110 receives the filtered signal 118A and provides the output RF signal 120A. For example, the first capacitor 110 has a capacitance that balances the reactance of the first filter 106 with respect to the reactance of the RF coil 114. For example, the first capacitor 110 has a capacitance that achieves a first reactance of the first filter 106 and a second reactance of the RF coil 114. In this example, the first reactance is within a predetermined range from the amplitude of the second reactance and has an amplitude in an opposite direction to the direction of the second reactance. In this example, the capacitance of the first capacitor 110 reduces the low-frequency resonant frequency of the LFMPS 102. As another example, the first capacitor 110 has a capacitance that cancels the reactance of the first filter 106 with respect to the reactance of the RF coil 114. Illustratively, the first capacitor 110 has a capacitance that achieves a first reactance of the first filter 106 and a second reactance of the RF coil 114. In this illustration, the first reactance is equal in magnitude and opposite in direction to the second reactance. In this illustration, the capacitance of the first capacitor 110 lowers the low frequency resonant frequency of the LFMPS 102. An output RF signal 120A is provided from the capacitor 110 to a point 122.

[0078] As an example, the first reactance described herein has a first sign (e.g., a positive sign or a negative sign, etc.) and the second reactance described herein has a second sign (e.g., a negative sign or a positive sign, etc.). In this example, the second sign is the opposite of the first sign. For example, when the first reactance is positive, the second reactance is negative, and when the first reactance is negative, the second reactance is positive. As another example, when the first reactance is a positive value, the second reactance is negative, and when the first reactance is a negative value, the second reactance is positive.

[0079] Similarly, the HFMPS 104 generates an RF signal 116B and provides the RF signal 116B to the second filter 108. The RF signal 116B is a sinusoidal waveform. For example, the RF signal 116B has the shape of a sinusoidal signal. The second filter 108 passes the high frequency of the RF signal 116B and outputs a filtered signal 118B. For example, the high frequency of the filtered signal 118B is the same as the high frequency of the RF signal 116B.

[0080] The second filter 108 provides the filtered signal 118B to the second capacitor 112. The second capacitor 112 receives the filtered signal 118B and provides the output RF signal 120B. For example, the second capacitor 112 has a capacitance that balances the reactance of the second filter 108 with respect to the reactance of the RF coil 114. For example, the second capacitor 112 has a capacitance that achieves a first reactance of the second filter 108 and a second reactance of the RF coil 114. In this example, the first reactance is within a predetermined range from the amplitude of the second reactance and has an amplitude in a direction opposite to that of the second reactance. In this example, the capacitance of the second capacitor 112 increases the high-frequency resonant frequency of the HFMPS 104. As another example, the second capacitor 112 has a capacitance that cancels the reactance of the second filter 108 with respect to the reactance of the RF coil 114. To further illustrate, the second capacitor 112 has a capacitance that achieves a first reactance of the second filter 108 and a second reactance of the RF coil 114. In this example, the first reactance is equal in magnitude and opposite in direction to the second reactance. In this example, the capacitance of the second capacitor 112 increases the high frequency resonant frequency of the HFMPS 104. The second capacitor 112 provides an output RF signal 120B to a point 122. The output RF signals 120A and 120B are combined at the point 122 to generate a combined RF signal 123, which is provided to the end E1.

[0081] A plasma is generated or maintained in the plasma chamber when one or more process gases are supplied to the plasma chamber in addition to the output RF signals 120A and 120B. Examples of the one or more process gases include an oxygen-containing gas, a nitrogen-containing gas, a fluorine-containing gas, and combinations of two or more thereof.

[0082] The RF power from the plasma is reflected in the form of a reflected RF signal 115. The reflected RF signal 115 is received by a point 122 from the plasma in the plasma chamber and split into a reflected RF signal 124A and a reflected RF signal 124B. The RF power of the reflected RF signal 115 is reflected from the plasma chamber through the RF coil 114 towards the point 122. The reflected RF signal 124A is provided from the point 122 to the second capacitor 112. The reflected RF signal 115 and the reflected RF signal 124A have a combination of low and high frequencies. The second capacitor 112 modifies the impedance of the reflected RF signal 124A to provide an output RF signal 126A to the filter 108. For example, the second capacitor 112 balances between the reactances of the RF coil 114 and the second filter 108 in a manner similar to that described above to provide the output RF signal 126A. Illustratively, the second capacitor 112 reduces the impedance of the reflected RF signal 124A to a minimal amount, such as to zero or near zero, and provides the output RF signal 126A to the second filter 108. The second filter 108 filters out low frequencies from the output RF signal 126A and outputs a filtered signal 128A. An example of filtering out frequencies includes removing frequencies. An example of filtering out frequencies includes lowering frequencies. The filtered signal 128A has a small amount or no amount of low frequencies to protect the HFMPS 104 from damage from low frequencies.

[0083] Similarly, the reflected RF signal 124B is reflected from the point 122 to the first capacitor 110. The reflected RF signal 124B has a combination of low and high frequencies. The first capacitor 110 modifies the impedance of the reflected RF signal 124B to provide the output RF signal 126B to the first filter 106. For example, the first capacitor 110 balances the reactance of the RF coil 114 and the first filter 106 in a similar output manner to the above to provide the output RF signal 126B. By way of example, the first capacitor 110 reduces the impedance of the reflected RF signal 124B to a minimum amount, such as to zero or close to zero, to provide the output RF signal 126B to the first filter 106. The first filter 106 filters out, such as by lowering or removing, the high frequencies of the output RF signal 126B to output a filtered signal 128B. The filtered signal 128B has a low or zero amount of high frequencies to protect the LFMPS 102 from being damaged by high frequencies.

[0084] The first filter 106 filters out high frequencies, which include a certain range of frequencies. For example, the first filter 106 filters out frequencies within a predetermined range from the high frequencies. For example, the first filter 106 removes frequencies in a range from 26.7 MHz to 27.3 MHz in order to filter out the high frequency of 27 MHz of the output RF signal 126B. Similarly, the second filter 108 filters out low frequencies, which include a certain range of frequencies. For example, the second filter 108 filters out frequencies within a predetermined range from the low frequencies. For example, the second filter 108 filters out frequencies in a range from 380 kHz to 430 kHz in order to filter out the low frequency of 400 kHz of the output RF signal 126A.

[0085] It should further be noted that there is no matcher, such as an impedance matching network or impedance matching circuit or impedance matching system or impedance matching electrical circuit or impedance matcher, between the LFMPS 102 and the RF coil 114. For example, there is no physical housing, such as a housing or physical container for the matcher, between the LFMPS 102 and the RF coil 114. Similarly, there is no matcher between the HFMPS 104 and the RF coil 114. For example, there is no physical housing, such as a housing or physical container for the matcher, between the HFMPS 104 and the RF coil 114.

[0086] In one embodiment, a substrate support such as a chuck is used rather than the RF coil 114. The chuck is made from a metal such as aluminum or an alloy of aluminum.

[0087] In one embodiment, the system 100 does not include the first filter 106. In this embodiment, the LFMPS 102 is coupled to the first capacitor 110 rather than being coupled to the first filter 106.

[0088] In one embodiment, the system 100 does not include the second filter 108. In this embodiment, the HFMPS 104 is coupled to the second capacitor 112 rather than being coupled to the second filter 108.

[0089] In one embodiment, the LFMPS 102 is coupled to the first filter 106 via an RF connection, the first filter 106 is coupled to the first capacitor 110 via an RF connection, and the first capacitor 110 is coupled to point 122 via an RF connection. Similarly, the HFMPS 104 is coupled to the second filter 108 via an RF connection, the second filter 108 is coupled to the second capacitor 112 via an RF connection, and the second capacitor 112 is coupled to point 122 via an RF connection. In this embodiment, RF signals 116A and 128B are communicated between the LFMPS 102 and the first filter 106 via the RF connection between the LFMPS 102 and the first filter 106. Also, RF signals 118A and 126B are communicated between the first filter 106 and the first capacitor 110 via the RF connection between the first filter 106 and the first capacitor 110. Further, RF signals 120A and 124B are communicated between the first capacitor 110 and point 122 via an RF connection between the first capacitor 110 and point 122. Further, RF signals 116B and 128A are communicated between the HFMPS 104 and the second filter 108 via an RF connection between the HFMPS 104 and the second filter 108. Further, RF signals 118B and 126A are communicated between the second filter 108 and the second capacitor 112 via an RF connection between the second filter 108 and the second capacitor 112. Further, RF signals 120B and 124A are communicated between the second capacitor 112 and point 122 via an RF connection between the second capacitor 112 and point 122.

[0090] In one embodiment, a bottom electrode, such as a plate or ring in the substrate support, is used rather than the RF coil 114. For example, the point 122 is coupled to the bottom electrode. Examples of bottom electrodes and substrate supports are described below.

[0091] In one embodiment, HFMPS 104 is turned on to generate RF signal 116B for a predetermined time while LFMPS 102 remains off. Once a plasma is ignited or struck in the plasma chamber within the predetermined time, LFMPS 102 is turned on to generate RF signal 116A. Once LFMPS 102 is turned on, HFMPS 104 is turned off or remains on.

[0092] In one embodiment, the LFMPS 102 is turned on to generate the RF signal 116A for a predetermined time and the HFMPS 104 is turned on to generate the RF signal 116B for a predetermined time. Once a plasma is ignited or struck in the plasma chamber within the predetermined time, the HFMPS 104 is turned off or remains on.

[0093] In one embodiment, an LFMPS is used instead of the HFMPS 104. The operating frequency of the LFMPS is the same as the operating frequency of the LFMPS 102.

[0094] In one embodiment, the HFMPS is used instead of the LFMPS 102. The operating frequency of the HFMPS is the same as the operating frequency of the HFMPS 104.

[0095] In one embodiment, the end E2 of the RF coil 114 is coupled to ground potential via a termination capacitor, for example, the end E2 of the RF coil 114 is coupled to a first end of a termination capacitor, and the second end of the termination capacitor is coupled to ground potential.

[0096] 2A is a diagram of one embodiment of a low pass filter 200. Filter 200 is an example of first filter 106 of FIG. 1. Filter 200 includes an inductor 202, another inductor 204, a capacitor 206, and another capacitor 208.

[0097] An input In of the filter 200 is coupled to the LFMPS 102, and an output Out of the filter 200 is coupled to a first capacitor 110 (FIG. 1). The input In of the filter 200 is coupled to an inductor 202, which is coupled to an inductor 204 and to a first end of a capacitor 206. The inductor 204 is coupled to an output Out of the filter 200 and to a first end of a capacitor 208. A first end of the capacitor 208 is coupled to the output Out of the filter 200. A second end of the capacitor 208 is coupled to ground potential, and a second end of the capacitor 206 is coupled to ground potential.

[0098] The first filter 200 receives the RF signal 116A, passes low frequencies of the RF signal 116A, and outputs a filtered RF signal 118A. The filter 200 also receives the output RF signal 126B at an output Out of the filter 200, filters out high frequencies of the output RF signal 126B, and provides a filtered signal 128B at an input In of the filter 200.

[0099] 2B is a diagram of one embodiment of a high pass filter 230. Filter 230 is an example of second filter 108 of FIG. 1. Filter 230 includes a capacitor 232, a capacitor 234, an inductor 236, and an inductor 238.

[0100] An input In of filter 230 is coupled to HFMPS 104 and an output Out of filter 230 is coupled to second capacitor 112 (FIG. 1). The input In of filter 230 is coupled to capacitor 232, which is coupled to a first end of inductor 236 and to capacitor 234. Capacitor 234 is coupled to an output Out of filter 230 and to a first end of inductor 238. A second end of inductor 236 is coupled to ground potential and a second end of inductor 238 is coupled to ground potential.

[0101] A first filter 230 receives RF signal 116B and passes high frequencies of RF signal 116B to output a filtered RF signal 118B. Filter 230 also receives output RF signal 126A at an output Out of filter 230 and filters out low frequencies of output RF signal 126A to provide a filtered signal 128A at an input In of filter 230.

[0102] 2C is a diagram of an embodiment of a bandpass filter 250, such as a lowpass filter or a highpass filter. Filter 250 is an example of first filter 106 or second filter 108 of FIG. 1. Filter 250 includes an inductor 252, another inductor 254, an inductor 256, a capacitor 258, a capacitor 260, and a capacitor 262.

[0103] When the filter 250 is used as the first filter 106 (e.g., a low-pass filter), the input In of the filter 250 is coupled to the LFMPS 102 and the output Out of the filter 250 is coupled to the first capacitor 110 (FIG. 1). When the filter 250 is used as the second filter 108 (e.g., a high-pass filter), the input In of the filter 250 is coupled to the HFMPS 104 and the output Out of the filter 250 is coupled to the second capacitor 112 (FIG. 1).

[0104] An input In of filter 250 is coupled to inductor 252, which is coupled in series with capacitor 258. Capacitor 258 is coupled to a first end of capacitor 260, to a first end of inductor 256, and to inductor 254. A first end of capacitor 260 is coupled to a first end of inductor 256 and to inductor 254. Inductor 254 is coupled in series with capacitor 262, which is coupled to an output Out of filter 250. A second end of capacitor 260 is coupled to ground potential, and a second end of inductor 256 is coupled to ground potential.

[0105] When filter 250 is used as first filter 106, filter 250 receives RF signal 116A, passes low frequencies of RF signal 116A, and outputs filtered RF signal 118A. Filter 250 also receives output RF signal 126B at an output Out of filter 250, filters out high frequencies of output RF signal 126B, and provides filtered signal 128B at an input In of filter 250.

[0106] When filter 250 is used as second filter 108, filter 250 receives RF signal 116B, passes the high frequencies of RF signal 116B, and outputs filtered RF signal 118B. In this case, filter 250 receives output RF signal 126A at an output Out of filter 250, filters out the low frequencies of output RF signal 126A, and provides filtered signal 128A at an input In of filter 250.

[0107] 2D is a diagram of an embodiment of a bandpass filter 270, such as a lowpass filter or a highpass filter. The bandpass filter 270 is a series resonant circuit. The filter 270 is an example of the first filter 106 or 108 of FIG. 1. The filter 270 includes an inductor 272 and a capacitor 274 coupled in series with each other.

[0108] When the filter 270 is used as the low-pass first filter 106, the input In of the filter 270 is coupled to the LFMPS 102 and the output Out of the filter 270 is coupled to the first capacitor 110 (FIG. 1). When the filter 270 is used as the high-pass second filter 108, the input In of the filter 270 is coupled to the HFMPS 104 and the output Out of the filter 270 is coupled to the second capacitor 112 (FIG. 1).

[0109] An input In of filter 270 is coupled to an inductor 272, which is coupled in series with a capacitor 274. Capacitor 274 is coupled to an output Out of filter 270.

[0110] When filter 270 is used as first filter 106, filter 270 receives RF signal 116A, passes low frequencies of RF signal 116A, and outputs filtered RF signal 118A. Filter 270 also receives output RF signal 126B at an output Out of filter 270, filters out high frequencies of output RF signal 126B, and provides filtered signal 128B at an input In of filter 270.

[0111] When filter 270 is used as second filter 108, filter 270 receives RF signal 116B, passes the high frequencies of RF signal 116B, and outputs filtered RF signal 118B. In this case, filter 270 receives output RF signal 126A at an output Out of filter 270, filters out the low frequencies of output RF signal 126A, and provides filtered signal 128A at an input In of filter 270.

[0112] 3A is a diagram of an embodiment of a plasma system 300 to illustrate the use of the LFMPS 102 and the HFMPS 104 in the plasma system 300. The plasma system 300 includes the LFMPS 102, the HFMPS 104, a first filter 106, a second filter 108, a first capacitor 110, a second capacitor 112, an LF bias RF generator (RFG) 302, an HF bias RFG 304, a matcher 306, and a plasma chamber 308.

[0113] An example of the LF bias RFG is an RF generator that operates at a low frequency to generate an RF signal having a low frequency. For example, the operating frequency of the LF bias RFG 302 is different from the operating frequency of the LFMPS 102. For further example, the operating frequency of the LF bias RFG 302 is 2 MHz, and the operating frequency of the LFMPS 102 is 400 kHz. For another example, the frequency of the RF signal generated by the LF bias RFG 302 is the same (e.g., equal) to the frequency of the RF signal 116A generated by the LFMPS 102. Similarly, an example of the HF bias RFG 304 is an RF generator that operates at a high frequency to generate an RF signal having a high frequency. For example, the operating frequency of the HF bias RFG 304 is different from the operating frequency of the HFMPS 104. For further example, the operating frequency of the HF bias RFG 304 is 60 MHz, and the operating frequency of the HFMPS 104 is 27 MHz. For another example, the operating frequency of the HF bias RFG 304 is the same as the operating frequency of the HFMPS 104.

[0114] The matching box described herein includes one or more branch circuits. As an example, the matching box has a housing or enclosure. Examples of the matching box include an impedance matching network and an impedance matching circuit. For example, each branch circuit of the matching box includes one or more electric circuit components, such as an inductor, a resistor, and a capacitor. For further example, each branch circuit includes a series circuit, a shunt circuit, or a combination thereof. The shunt circuit is coupled to the series circuit at one end and coupled to a ground potential at the opposite end. As an example, the series circuit includes two or more electric circuit components coupled in series with each other, and the shunt circuit includes two or more electric circuit components coupled in series with each other. As another example, the series circuit includes at least one electric component, and the shunt circuit includes at least one electric circuit component.

[0115] The matcher 306 includes a first branch circuit coupled between an input 324A of the matcher 306 and an output 326 of the matcher 306. The matcher 306 also includes a second branch circuit coupled between another input 324B of the matcher 306 and the output 326.

[0116] The plasma chamber 308 includes a substrate support 310 and an RF coil 312. A substrate S, such as a semiconductor wafer, is placed on the upper surface of the substrate support 310. The RF coil 312 has two turns and is an example of the RF coil 114 (FIG. 1). An example of the substrate support 310 is a chuck, such as an electrostatic chuck (ESC). The substrate support 310 includes a lower electrode 311, which is made of a metal, such as aluminum or an alloy of aluminum. The plasma chamber 308 includes a dielectric window 314. For example, the dielectric window 314 forms a top wall of the plasma chamber 308. The RF coil 312 is located above the dielectric window 314.

[0117] Point 122 is coupled to end 316 of RF coil 312 via RF connection 125. The opposite end 318 of RF coil 312 is coupled to ground potential.

[0118] The LF bias RFG 302 is coupled to an input 324A of the matcher 306 via an RF cable 320, and the HF bias RFG 304 is coupled to an input 324B of the matcher 306 via an RF cable 322. The output 326 of the matcher 306 is coupled to the bottom electrode 311 of the substrate 310 via an RF transmission line 328. An example of an RF transmission line used herein is an RF rod surrounded by an RF sheath. There is an insulating material between the RF rod and the RF sheath. Another example of an RF transmission line is a combination of an RF rod and one or more RF straps. Illustratively, an RF rod is surrounded by an RF sheath, coupled to the bottom electrode 311, and coupled to the output 326 via an RF strap.

[0119] The composite RF signal 123 is transmitted from point 122 through RF connection 125 to end 316. LF bias RFG 302 generates RF signal 330 and transmits RF signal 330 to input 324A. Similarly, HF bias RFG 304 generates RF signal 332 and transmits RF signal 332 through RF cable 322 to input 324B. Matching device 306 receives RF signals 330 and 332 and modifies the impedance of RF signals 330 and 332 to match the impedance of a load coupled to output 326 and the impedance of a source coupled to inputs 324A and 324B. Examples of loads coupled to output 326 include RF transmission line 328 and plasma chamber 308. Examples of sources coupled to inputs 324A and 324B include RF cables 320 and 322, and bias RF generators 302 and 304. The impedance of RF signal 330 is modified by a first branch of matcher 306 to output a first modified RF signal, and the impedance of RF signal 332 is modified by a second branch of matcher 306 to output a second modified RF signal. The first and second modified RF signals are combined, such as by being added, at output 326 to provide modified RF signal 334 at output 326. Modified RF signal 334 is transmitted from output 326 via RF transmission line 328 to lower electrode 311.

[0120] When one or more process gases are provided to the plasma chamber 308 in addition to the composite RF signals 123 and 334, a plasma is generated or maintained in the plasma chamber 308. When a plasma is generated or maintained in the plasma chamber 308, the substrate S is processed and the reflected RF signal 115 is reflected from the plasma chamber 308 to the point 122 through the RF connection 125. For example, the reflected RF signal 115 is reflected from the plasma chamber 308 to the point 122 through the RF connection 125. Examples of processing the substrate S include depositing a metal or oxide on top of the substrate S, etching the substrate S, cleaning the substrate S, and sputtering the substrate S.

[0121] In one embodiment, the RF coil 312 has a different number of turns than shown in FIG. 3A.

[0122] In one embodiment, each turn of the RF coil 312 lies in a different plane.

[0123] 3B is a diagram of an embodiment of a plasma system 350 to illustrate the use of the LFMPS 102 and HFMPS 104 when the lower electrode 311 is coupled to ground potential. The plasma system 350 includes the LFMPS 102, the HFMPS 104, the first filter 106, the second filter 108, the first capacitor 110, the second capacitor 112, and a plasma chamber 308. While the lower electrode 311 is coupled to ground potential, the composite RF signal 123 is generated in a similar manner as described above and provided to the RF coil 312.

[0124] A plasma is generated or sustained in the plasma chamber 308 when one or more process gases are provided to the plasma chamber 308 in addition to the composite RF signal 123. When the plasma is generated or sustained, the reflected RF signal 115 is reflected from the plasma chamber 308 towards a point 122.

[0125] 4 is a diagram of an embodiment of a system 400 to illustrate the use of an LF source RFG 402 and an HF source RFG 404 to provide RF power to the RF coil 114. The system 400 includes an LF source RFG 402 and an HF source RFG 404. The system 400 further includes a dual frequency matcher 406 and the RF coil 114.

[0126] An example of an LF source RFG is an RF generator that operates at a low frequency to generate an RF signal having a low frequency. Illustratively, the operating frequency of the LF source RFG 402 is different from the operating frequency of the LFMPS 102 (FIG. 1). Illustratively, the operating frequency of the LF source RFG is 2 MHz, and the operating frequency of the LFMPS 102 is 400 kHz. As another example, the frequency of the RF signal 420 generated by the LF source RFG 402 is different from the frequency of the RF signal 116A generated by the LFMPS 102. As yet another example, the frequency of the RF signal 420 generated by the LF source RFG 402 is the same (e.g., equal) as the operating frequency of the LFMPS 102.

[0127] Similarly, an example of the HF source RFG 404 is an RF generator that operates at a high frequency to generate an RF signal having a high frequency. Illustratively, the operating frequency of the HF source RFG 404 is different from the operating frequency of the HFMPS 104. Illustratively, the operating frequency of the HF source RFG 404 is 60 MHz, and the operating frequency of the HFMPS 104 is 27 MHz. As another illustrative example, the operating frequency of the HF source RFG 404 is the same as the operating frequency of the HFMPS 104.

[0128] The LF source RFG 402 is coupled to an input 410 of a dual frequency matcher 406 via an RF cable 408, and the HF source RFG is coupled to another input 414 of the dual frequency matcher 406 via another RF cable 412. An output 416 of the dual frequency matcher 406 is coupled to end E1 of the RF coil 114 via an RF connection 418.

[0129] The LF source RFG 402 generates an RF signal 420 and provides the RF signal 420 to the input 410 via an RF cable 408. The RF signal 420 has a low frequency. Additionally, the HF source RFG 404 generates an RF signal 422 and provides the RF signal 422 to the input 414 via an RF cable 412. The RF signal 422 has a high frequency. The dual frequency matcher 406 receives the RF signals 420 and 422 and modifies the impedance of the RF signals 420 and 422 to match the impedance of the load coupled to the output 416 and the impedance of the source coupled to the inputs 410 and 414. Examples of the load coupled to the output 416 include an RF connection 418 and a plasma chamber including an RF coil 114. Examples of the source coupled to the inputs 410 and 414 include the RF cables 408 and 412 and the source RF generators 402 and 404. The impedance of the RF signal 420 is modified by a first branch of the dual frequency matcher 406 to output a first modified RF signal, and the impedance of the RF signal 422 is modified by a second branch of the dual frequency matcher 406 to output a second modified RF signal. The first and second modified RF signals are combined, such as by being added, at the output 416 to provide a modified RF signal 426 at the output 416. The modified RF signal 426 is transmitted from the output 416 via an RF connection 418 to the RF coil 114.

[0130] A plasma is generated or maintained in the plasma chamber when one or more process gases are supplied to the plasma chamber, including the RF coil 114, in addition to the modified RF signal 426. When the plasma is generated or maintained, RF power is reflected back towards the dual frequency matcher 406 in the form of a reflected RF signal 428.

[0131] In one embodiment, HF source RFG 404 is turned on to generate RF signal 422 for a predetermined time while LF source RFG 402 remains off. Once a plasma is ignited or struck in the plasma chamber within the predetermined time, LF source RFG 402 is turned on to generate RF signal 420. Once LF source RFG 402 is turned on, HF source RFG 404 is turned off or remains on.

[0132] In one embodiment, LF source RFG 402 is turned on to generate RF signal 420 for a predetermined time and HF source RFG 404 is turned on to generate RF signal 422 for a predetermined time. Once a plasma is ignited or struck in the plasma chamber within the predetermined time, HF source RFG 404 is turned off or remains on.

[0133] 5A is a diagram of an embodiment of a dual-frequency matching device 500, which is an example of the dual-frequency matching device 406. The dual-frequency matching device 500 includes a branch circuit 501, which includes a filter 506, a shunt circuit 504, a series circuit 507, and another filter 508. The dual-frequency matching device 500 includes another branch circuit 503, which includes a filter 510, a series circuit 512, a shunt circuit 514, another series circuit 516, and a filter 518. An example of the filter 506 is the first filter 106 (FIG. 1), and an example of the filter 508 is the first filter 106. Also, an example of the filter 510 is the second filter 108 (FIG. 1), and an example of the filter 518 is the second filter 108. An example of the shunt circuit is a variable capacitor or a fixed capacitor, and an example of the series circuit is a variable capacitor or a fixed capacitor.

[0134] The filter 506 is coupled to the input 410 and to an end of the shunt circuit 504. The opposite end of the shunt circuit 504 is coupled to ground potential. The filter 506 is coupled to a series circuit 507, which is coupled to a filter 508. The filter 508 is coupled to the output 416.

[0135] Similarly, filter 510 is coupled to the input 414 and to an end of series circuit 512. Series circuit 512 is coupled to an end of shunt circuit 514. The opposite end of shunt circuit 514 is coupled to ground potential. Shunt circuit 514 and series circuit 512 are coupled to series circuit 516. Series circuit 516 is coupled to filter 518, which is coupled to output 416.

[0136] Filter 506 receives RF signal 420 at its input, passes low frequencies of RF signal 420, and provides a filtered signal 505 at its output. Shunt circuit 504 and series circuit 507 modify the impedance of filtered RF signal 505 to provide a modified RF signal 509 at the output of series circuit 507. Filter 508 passes low frequencies of modified RF signal 509 to provide a filtered signal 511 at its output.

[0137] Similarly, filter 510 receives RF signal 422 at its input, passes high frequencies of RF signal 422, and outputs filtered RF signal 513 at its output. Series circuit 512, shunt circuit 514, and series circuit 516 modify the impedance of filtered RF signal 513 to provide modified RF signal 515 at the output of series circuit 516. Filter 518 passes high frequencies of modified RF signal 515 and outputs filtered signal 517 at its output. Filtered signal 511 is combined, such as by being summed, with filtered signal 517 to generate modified RF signal 426, which is transmitted to RF coil 114 via output 416.

[0138] The reflected RF signal 428 is split at the output 416 into a reflected RF signal 520 and another reflected RF signal 522. The reflected RF signal 520 is transmitted from the output 416 to a filter 508, and the reflected RF signal 522 is transmitted from the output 416 to a filter 518.

[0139] The reflected RF signal 520 has high frequencies, which are filtered by the filter 508 to provide a filtered signal 524 at the input of the filter 508. The impedance of the filtered signal 524 is modified by the series circuit 507 and the shunt circuit 504 to output a modified RF signal 526. The filter 506 filters out the high frequencies of the modified RF signal 526 to provide a filtered signal 528 at the input of the filter 506. As an example, the filtered signal 528 has low frequencies and does not include high frequencies. As another example, the filtered signal 528 has a minimal amount of high frequencies and a maximal amount of low frequencies. The filtered signal 528 has a minimal amount or no high frequencies that interfere with the low frequencies of the RF signal 420. The filtered signal 528, when received by the LF source RFG 402 via the RF cable 408, does not damage the LF source RFG 402 or causes minimal damage to the LF source RFG 402.

[0140] Similarly, the reflected RF signal 522 has low frequencies that are filtered by the filter 518 to provide a filtered signal 530 at the input of the filter 518. The impedance of the filtered signal 530 is modified by the series circuit 516, the shunt circuit 514, and the series circuit 512 to output a modified RF signal 532. The filter 510 filters out the low frequencies of the modified RF signal 532 to provide a filtered signal 534 at the input of the filter 510. As an example, the filtered signal 534 has high frequencies and does not include low frequencies. As another example, the filtered signal 534 has a minimum amount of low frequencies and a maximum amount of high frequencies. The filtered signal 524 has a minimum amount or no low frequencies that interfere with the high frequencies of the RF signal 422. The filtered signal 534, when received by the HF source RFG 404 via the RF cable 412, does not damage the HF source RFG 404 or causes minimal damage to the HF source RFG 404.

[0141] 5B is a diagram of an embodiment of a dual-frequency matching device 550, which is another example of the dual-frequency matching device 406 of FIG. 4. The dual-frequency matching device 550 has the same structure and function as the dual-frequency matching device 500 and FIG. 5A, except that the dual-frequency matching device 550 does not include filters 508 and 518. Instead, the series circuit 507 is coupled to the output 416, and the series circuit 516 is coupled to the output 416. For example, the dual-frequency matching device 550 includes a branch circuit 531, which includes a filter 506, a shunt circuit 504, and a series circuit 507. Also, in this example, the low-frequency matching device 550 includes a branch circuit 533, which includes a filter 510, a series circuit 512, a shunt circuit 514, and a series circuit 516.

[0142] The impedance of the reflected RF signal 520 is modified by the series circuit 507 and the shunt circuit 504 to provide a modified RF signal 552 to the filter 506. The filter 506 filters, such as removing or reducing high frequencies, the modified RF signal 552 to provide a filtered signal 554 at the input of the filter 506. As an example, the filtered signal 554 has low frequencies and does not include high frequencies. As another example, the filtered signal 554 has a minimal amount of high frequencies and a maximal amount of low frequencies. The filtered signal 554 has a minimal amount or no high frequencies interfering with the low frequencies of the RF signal 420. The filtered signal 554, when received by the LF source RFG 402 via the RF cable 408, does not damage the LF source RFG 402 or causes a negligible amount of damage to the LF source RFG 402.

[0143] Similarly, the impedance of the reflected RF signal 522 is modified by the series circuit 516, the shunt circuit 514, and the series circuit 512 to provide a modified RF signal 555 to the filter 510. The filter 510 filters, such as removing or reducing low frequencies, the modified RF signal 555 to provide a filtered signal 556 at the input of the filter 510. As an example, the filtered signal 556 has high frequencies and no low frequencies. As another example, the filtered signal 556 has a minimal amount of low frequencies and a maximal amount of high frequencies. The filtered signal 556 has a minimal amount or no low frequencies that interfere with the high frequencies of the RF signal 422. The filtered signal 556, when received by the HF source RFG 404 via the RF cable 412, does not damage the HF source RFG 404 or causes a negligible amount of damage to the HF source RFG 404.

[0144] 5C is a diagram of an embodiment of a dual-frequency matcher 570, which is yet another example of the dual-frequency matcher 406 of FIG. 4. The dual-frequency matcher 570 has the same structure and function as the dual-frequency matcher 500 and FIG. 5A, except that the dual-frequency matcher 570 does not include filters 506 and 510. Instead, a shunt circuit 504 and a series circuit 507 are coupled to the input 410. Also, a series circuit 512 is coupled to the input 414. For example, the dual-frequency matcher 570 includes a branch circuit 571, which includes a shunt circuit 504, a series circuit 507, and a filter 508. Also, in this example, the dual-frequency matcher 570 includes a branch circuit 573, which includes a series circuit 512, a shunt circuit 514, a series circuit 516, and a filter 518.

[0145] The modified RF signal 526 is reflected back towards the LF source RFG 402 (FIG. 4) via the RF cable 408. The modified RF signal 526 is generated based on the filtered signal 524. Thus, as an example, the modified RF signal 526 has low frequencies and does not include high frequencies. As another example, the modified RF signal 526 has a minimal amount of high frequencies and a maximal amount of low frequencies. The modified RF signal 526 has a minimal amount or no high frequencies interfering with the low frequencies of the RF signal 420. The modified RF signal 526, when received via the RF cable 408 by the LF source RFG 402, does not damage the LF source RFG 402 or causes a negligible amount of damage to the LF source RFG 402.

[0146] Similarly, the modified RF signal 532 is reflected back through the RF cable 412 towards the HF source RFG 404 (FIG. 4). The modified RF signal 532 is generated based on the filtered signal 530. Thus, as an example, the modified RF signal 532 has high frequencies and does not include low frequencies. As another example, the modified RF signal 532 has a minimal amount of low frequencies and a maximal amount of high frequencies. The modified RF signal 532 has a minimal amount or no low frequencies interfering with the high frequencies of the RF signal 422. The modified RF signal 532, when received through the RF cable 412 by the HF source RFG 405, does not damage the HF source RFG 404 or causes a negligible amount of damage to the HF source RFG 404.

[0147] 6A is a diagram of an embodiment of a plasma system 600 having an LF bias RFG 302 and an HF bias RFG 304 to illustrate the use of an LF source RFG 402 and an HF source RFG 404. The plasma system 600 includes an LF source RFG 402, an HF source RFG 404, a dual frequency matcher 406, a plasma chamber 308, an LF bias RFG 302, an HF bias RFG 304, and a matcher 306.

[0148] An output 416 of the dual frequency matcher 406 is coupled to the RF coil 312 of the plasma chamber 308 via an RF connection 418. A modified RF signal 426 is transmitted from the output 416 via the RF connection 418 to the RF coil 312, and a modified RF signal 334 is transmitted from the output 326 via an RF transmission line 328 to the lower electrode 311. A plasma is generated or sustained in the plasma chamber 308 when one or more process gases are supplied to the plasma chamber 308 in addition to the modified RF signals 326 and 334. When a plasma is generated or sustained, RF power embedded in the reflected RF signal 428 is reflected back towards the dual frequency matcher 406.

[0149] 6B is a diagram of one embodiment of a system 650 having a plasma chamber 308 with a lower electrode 311 coupled to ground potential to illustrate the use of an LF source RFG 402 and an HF source RFG 404. The system 650 includes an LF source RFG 402, an HF source RFG 404, a dual frequency matcher 406, and a plasma chamber 308. A plasma is generated or maintained in the plasma chamber 308 when a modified RF signal 426 is provided to the plasma chamber 308 and one or more process gases are provided to the plasma chamber 308. RF power is reflected from the plasma chamber 308 in a direction toward the LF source RFG 402 and the HF source RFG 404 in the form of a reflected RF signal 428.

[0150] 7A is a diagram of an embodiment of a system 700 having an HF source RFG 404 to illustrate the use of the LFMPS 102. The system 700 includes the LFMPS 102, the HF source RFG 404, the first filter 106, the first capacitor 110, a matching box 702, and an RF coil 114. As an example, referring to FIG. 5A, the matching box 702 does not include the branch circuit 501 but includes the branch circuit 503. As another example, referring to FIG. 5B, the matching box 702 does not include the branch circuit 531 but includes the branch circuit 533. As yet another example, referring to FIG. 5C, the matching box 702 does not include the branch circuit 571 but includes the branch circuit 573.

[0151] The HF source RFG 404 is coupled to a matcher 702, which is coupled to point 122. Upon receiving an RF signal 422 at its input, the matcher 702 modifies the impedance of the RF signal 422 to output a modified RF signal 704. For example, upon receiving an RF signal 422 at its input, the matcher 702 matches the impedance of a load coupled to the output of the matcher 702 with the impedance of a source coupled to the input of the matcher 702 to output a modified RF signal 704. An example of a load coupled to the output of the matcher 702 includes a plasma chamber having an RF coil 114. Another example of a load coupled to the output of the matcher 702 includes an RF connection between the output and point 122, another RF connection between point 122 and the RF coil 114, and a plasma chamber including the RF coil 114. An example of a source coupled to the input of the matcher 702 includes the HF source RFG 404 and an RF cable 412. The output RF signal 120 A and the modified RF signal 704 are combined, such as by being added, at point 122 to generate a combined RF signal 706 that is provided to the RF coil 114 via RF connection 125 .

[0152] When one or more process gases are supplied to the plasma chamber 308 (FIG. 3A) in addition to the composite RF signal 706, a plasma is generated or maintained in the plasma chamber. When the plasma is generated or maintained, RF power is reflected from the plasma in the form of a reflected RF signal 708. The reflected RF signal 708 is transmitted through the RF connection 125 and split at point 122 into a reflected RF signal 124B and a reflected RF signal 522. The reflected RF signal 124B is processed in the same manner by the first capacitor 110 and the first filter 106 as described above with reference to FIG. 1, and the reflected RF signal 522 is processed in the same manner as described above by the branch circuit 503 (FIG. 5A), or 533 (FIG. 5B), or 573 (FIG. 5C) to output a modified RF signal 710. The modified RF signal 710 is an example of any of the RF signals 534 (FIG. 5A), 556 (FIG. 5B), and 532 (FIG. 5C).

[0153] In one embodiment, the HF source RFG 404 is turned on to generate the RF signal 422 for a predetermined time while the LFMPS 102 remains off. Once a plasma is ignited or struck in the plasma chamber within the predetermined time, the LFMPS 102 is turned on to generate the RF signal 116A. Once the LFMPS 102 is turned on, the HF source RFG 404 is either turned off or remains on.

[0154] In one embodiment, the LFMPS 102 is turned on to generate the RF signal 116A for a predetermined time and the HF source RFG 404 is turned on to generate the RF signal 422 for a predetermined time. Once a plasma is ignited or struck in the plasma chamber within the predetermined time, the HF source RFG 404 is turned off or remains on.

[0155] In one embodiment, the matcher 702 is coupled to point 122 via an RF connection.

[0156] 7B is a diagram of an embodiment of a system 750 having an HFMPS 104 to illustrate the use of an LF source RFG 402. The system 750 includes an LF source RFG 402, a matcher 752, an HFMPS 104, a second filter 108, a second capacitor 112, and an RF coil 114. As an example, referring to FIG. 5A, the matcher 752 includes a branch circuit 501 without including a branch circuit 503. As another example, referring to FIG. 5B, the matcher 752 includes a branch circuit 531 without including a branch circuit 533. As yet another example, referring to FIG. 5C, the matcher 752 includes a branch circuit 571 without including a branch circuit 573.

[0157] The LF source RFG 402 is coupled to a matcher 752, which is coupled to point 122. Upon receiving an RF signal 420 at its input, the matcher 752 modifies the impedance of the RF signal 420 to output a modified RF signal 754. For example, the matcher 752 matches the impedance of a load coupled to the output of the matcher 752 with the impedance of a source coupled to the input of the matcher 752 to output the modified RF signal 754. An example of a load coupled to the output of the matcher 752 includes a plasma chamber having an RF coil 114. Another example of a load coupled to the output of the matcher 752 includes an RF connection between the output and point 122, another RF connection between point 122 and the RF coil 114, and a plasma chamber including the RF coil 114. An example of a source coupled to the input of the matcher 752 includes the LF source RFG 402 and an RF cable 408. The modified RF signal 754 and the output RF signal 120 B are combined, such as by being added, at point 122 to generate a combined RF signal 756 that is provided to the RF coil 114 via RF connection 125 .

[0158] A plasma is generated or maintained in the plasma chamber when one or more process gases are supplied to the plasma chamber in addition to the composite RF signal 756. When the plasma is generated or maintained, RF power is reflected from the plasma in the form of a reflected RF signal 758. The reflected RF signal 758 travels through the RF connection 125 and is split at point 122 into a reflected RF signal 124A and a reflected RF signal 520. The reflected RF signal 124A is processed in the same manner by the second capacitor 112 and the second filter 108 as described above with reference to FIG. 1, and the reflected RF signal 520 is processed in the same manner as described above by the branch circuit 501 (FIG. 5A), or 531 (FIG. 5B), or 571 (FIG. 5C) to output a modified RF signal 760. The modified RF signal 760 is an example of any of the RF signals 528 (FIG. 5A), 554 (FIG. 5B), and 526 (FIG. 5C).

[0159] In one embodiment, HFMPS 104 is turned on to generate RF signal 116B for a predetermined time while LF source RFG 402 remains off. Once a plasma is ignited or struck in the plasma chamber within the predetermined time, LF source RFG 402 is turned on to generate RF signal 420. Once LF source RFG 402 is turned on, HFMPS 104 is either turned off or remains on.

[0160] In one embodiment, LF source RFG 402 is turned on to generate RF signal 420 for a predetermined time and HFMPS 104 is turned on to generate RF signal 116B for a predetermined time. Once a plasma is ignited or struck in the plasma chamber within the predetermined time, HFMPS 104 is turned off or remains on.

[0161] In one embodiment, the matcher 752 is coupled to point 122 via an RF connection.

[0162] 8A is a diagram of an embodiment of a system 800 having an LF bias RFG 302 and an HF bias RFG 304 to illustrate the use of the LFMPS 102 and the HF source RFG 404. The system 800 includes the LFMPS 102, the HF source RFG 404, the filter 106, the first capacitor 110, the matcher 702, the plasma chamber 308, the LF bias RFG 302, the HF bias RFG 304, and the matcher 306. The point 122 is coupled to the end 314 of the RF coil 312 via an RF connection 125.

[0163] The composite RF signal 706 is provided from point 122 via RF connection 125 to the RF coil 312. The modified RF signal 334 is also provided to the lower electrode 311 and a plasma is generated or maintained in the plasma chamber 308 when one or more process gases are provided to the plasma chamber 308. When the plasma is generated or maintained, a reflected RF signal 708 is reflected from the RF coil 312 via RF connection 125 towards point 122.

[0164] 8B is a diagram of one embodiment of a system 820 to illustrate the use of the LFMPS 102 and the HF source RFG 404 when the lower electrode 311 is coupled to ground potential. The system 820 includes the LFMPS 102, the first filter 106, the first capacitor 110, the HF source RFG 404, the matcher 702, and the plasma chamber 308. A plasma is generated or maintained in the plasma chamber 308 when a composite RF signal 706 is provided to the RF coil 312, the lower electrode is coupled to ground potential, and one or more process gases are provided to the plasma chamber 308. When the plasma is generated or maintained, a reflected RF signal 708 is reflected from the RF coil 312 through the RF connection 125 toward point 122.

[0165] 8C is a diagram of an embodiment of a system 840 having an LF bias RFG 302 and an HF bias RFG 304 to illustrate the use of an LF source RFG 402 and an HFMPS 104. The system 840 includes an LF source RFG 402, a matcher 752, an HFMPS 104, a second filter 108, a second capacitor 112, a plasma chamber 308, an LF bias RFG 302, an HF bias RFG 304, and a matcher 306. The point 122 is coupled to an RF coil 312 via an RF connection 125.

[0166] A plasma is generated or sustained in the plasma chamber 308 when the composite RF signal 756 is provided to the plasma chamber 308 via RF connection 125 in addition to the modified RF signal 334 and one or more process gases. When the plasma is generated or sustained, a reflected RF signal 758 is generated and transmitted to point 122 via RF connection 125.

[0167] 8D is a diagram of an embodiment of a system 860 to illustrate the use of the LF source RFG 402 and the HFMPS 104 when the lower electrode 311 is coupled to ground potential. The system 860 includes the LF source RFG 402, the HFMPS 104, the matcher 752, the second filter 108, the second capacitor 112, and the plasma chamber 308.

[0168] When the composite RF signal 756 is supplied along with one or more process gases to the plasma chamber 308 via RF connection 125 and the lower electrode 311 is coupled to ground potential, a plasma is generated or maintained in the plasma chamber 308. When a plasma is generated or maintained, RF power of the reflected RF signal 758 is reflected back towards point 122 via RF connection 125.

[0169] 9A is a diagram of an embodiment of a system 900 to illustrate a method of providing high frequencies to multiple RF coils 114 and 902 and providing low and high frequencies to the RF coil 114. The system 900 includes the LFMPS 102, a first filter 106, a first capacitor 110, the HFMPS 104, a second filter 108, a second capacitor 112, a signal splitter 906, and the RF coils 114 and 902. The signal splitter 906 includes a third capacitor 908 and a fourth capacitor 910. Both the RF coils 114 and 902 are of the same plasma chamber, which will be described below.

[0170] The second capacitor 112 is coupled to the capacitors 908 and 910 via a split point 912. As an example, the second capacitor 112 is coupled to the capacitors 908 and 910 via a split RF connection, such as a single RF strap split into two RF straps. In this example, the single RF strap is split at the split point 912. The third capacitor 908 is coupled to point 122 and the fourth capacitor 910 is coupled to end E3 of the RF coil 904. For example, the third capacitor 908 is coupled to point 122 via an RF connection and the fourth capacitor 910 is coupled to end E3 via an RF connection. The opposite end E4 of the RF coil 904 is coupled to ground potential.

[0171] The second capacitor 112 receives the filtered signal 118B from the second filter 108 and balances the reactance of the second filter 108 with the combined reactance of the RF coils 114 and 904 to provide the output RF signal 901. For example, the second capacitor 112 has a capacitance that achieves a first reactance of the second filter 108 and a second reactance that is the combined reactance of the RF coils 114 and 904. In this example, the first reactance is within a predetermined range from the amplitude of the second reactance and has an amplitude in the opposite direction to the direction of the second reactance. In this example, the capacitance of the second capacitor 112 increases the high-frequency resonant frequency of the HFMPS 104. As another example, the second capacitor 112 has a capacitance that cancels the reactance of the second filter 108 against the combined reactance of the RF coils 114 and 904. In this example, the second capacitor 112 has a capacitance that achieves a first reactance of the second filter 108 and a second reactance that is the combined reactance of the RF coils 114 and 904. In this example, the first reactance is equal in magnitude and opposite in direction to the second reactance. In this example, the capacitance of the second capacitor 112 increases the high frequency resonant frequency of the HFMPS 102. As an example, the combined reactance of the RF coils 114 and 904 is the sum or sum of the reactance of the RF coil 114 and the reactance of the RF coil 904. The output RF signal 901 is provided from the second capacitor 112 to a split point 912.

[0172] The output RF signal 901 is split at a split point 912 into an output RF signal 914 and an output RF signal 916. For example, the RF power of the output RF signal 902 is split into an RF power of the output RF signal 914 and an RF power of the output RF signal 916. The third capacitor 908 modifies the impedance of the output RF signal 914 to provide an output RF signal 918. For example, the third capacitor 908 balances the reactance of the second filter 108 with the reactance of the RF coil 114 to provide the output RF signal 918. Illustratively, the third capacitor 908 has a capacitance that achieves a first reactance of the second filter 108 and a second reactance of the RF coil 114. In this illustrative example, the first reactance is within a predetermined range from the amplitude of the second reactance and has an amplitude in a direction opposite to that of the second reactance. In this example, the capacitance of the third capacitor 908 increases the high frequency resonant frequency of the HFMPS 104. As another example, the third capacitor 908 has a capacitance that cancels the reactance of the second filter 108 with respect to the reactance of the RF coil 114. In this example, the third capacitor 908 has a capacitance that achieves a first reactance of the second filter 108 and a second reactance of the RF coil 114. In this example, the first reactance is equal in magnitude and opposite in direction to the second reactance. In this example, the capacitance of the third capacitor 908 increases the high frequency resonant frequency of the HFMPS 104. An output RF signal 918 is provided from the third capacitor 908 to a point 122.

[0173] Also, the fourth capacitor 910 modifies the impedance of the output RF signal 916 to provide the output RF signal 920. For example, the fourth capacitor 910 balances the reactance of the second filter 108 with respect to the reactance of the RF coil 904 to provide the output RF signal 920. For example, the fourth capacitor 910 has a capacitance that achieves a first reactance of the second filter 108 and a second reactance of the RF coil 904. In this example, the first reactance is within a predetermined range from the amplitude of the second reactance and has an amplitude in a direction opposite to that of the second reactance. In this example, the capacitance of the fourth capacitor 910 increases the high-frequency resonant frequency of the HFMPS 104. As another example, the fourth capacitor 910 has a capacitance that cancels the reactance of the second filter 108 with respect to the reactance of the RF coil 904. In one example, the fourth capacitor 910 has a capacitance that achieves a first reactance of the second filter 108 and a second reactance of the RF coil 904. In this example, the first reactance is equal in magnitude and opposite in direction to the second reactance. In this example, the capacitance of the fourth capacitor 910 increases the high frequency resonant frequency of the HFMPS 104. An output RF signal 920 is provided from the fourth capacitor 910 to the RF coil 904.

[0174] Output RF signals 914, 916, 918, and 920 have a high frequency. Output RF signal 120A has a low frequency.

[0175] Output RF signal 918 is combined, such as by being added, with output RF signal 120A to generate a combined RF signal 922 at point 122. The combined RF signal 922 has a combination of the high frequency of output RF signal 918 and the low frequency of output RF signal 120A. The combined RF signal 922 is communicated to end E1 of RF coil 114 via RF connection 125. Output RF signal 920 is also communicated from the fourth capacitor 910 to end E3 of RF coil 904.

[0176] When the composite RF signal 922 is provided to the RF coil 114 and the output RF signal 920 is provided to the RF coil 904, a plasma is generated or maintained in the plasma chamber. When the plasma is generated or maintained in the plasma chamber, RF power is reflected from the plasma chamber in the form of a reflected RF signal 924. The reflected RF signal 924 is transmitted to the point 122 via the RF coil 114, the end E1, and the RF connection 125. The reflected RF signal 124 is split into a reflected RF signal 124B and a reflected RF signal 926. The reflected RF signal 124B is provided from the point 122 to the first capacitor 110. The reflected RF signal 926 is provided from the point 122 to the third capacitor 908.

[0177] The third capacitor 908 modifies the impedance of the reflected RF signal 926 to provide an RF signal 928 to the capacitor 112. For example, the third capacitor 908 receives the RF signal 928 and balances the reactance of the second filter 108 and the RF coil 904 in a manner similar to that described above to provide the RF signal 928. Illustratively, the third capacitor 908 reduces the impedance of the reflected RF signal 926 to a minimal amount, such as to zero or close to zero, to provide the RF signal 928.

[0178] Also, when a plasma is generated or maintained in the plasma chamber, RF power is reflected from the plasma chamber in the form of a reflected RF signal 930. The reflected RF signal 930 is transmitted to the fourth capacitor 910 via the RF coil 904 and end E3. The fourth capacitor 910 modifies the impedance of the reflected RF signal 930 to output an RF signal 932 at its input. For example, the fourth capacitor 910 reduces the impedance of the reflected RF signal 930 to a minimal amount, such as to zero or close to zero, to provide the RF signal 932. The RF signals 928 and 932 are combined at the split point 912 to generate the reflected RF signal 124A. The reflected RF signal 124A is reflected from the split point 912 towards the second capacitor 112.

[0179] In one embodiment, the second capacitor 112 is coupled to a division point 912 via an RF connection, which is coupled to a third capacitor 908 via another RF connection. The division point 912 is also coupled to a capacitor bank 910 via an RF connection. The third capacitor 908 is further coupled to a point 122 via an RF connection, and the fourth capacitor 910 is coupled to an end E3 via an RF connection. In this embodiment, RF signals 124A and 120B are communicated between the second capacitor 112 and the division point 912 via an RF connection between the second capacitor 112 and the division point 912. RF signals 914 and 928 are also communicated between the division point 912 and the third capacitor 908 via an RF connection between the division point 912 and the third capacitor 908. Additionally, RF signals 916 and 932 are communicated between the division point 912 and the fourth capacitor 910 via an RF connection between the division point 912 and the fourth capacitor 910. Also, RF signals 918 and 926 are communicated between the third capacitor 908 and point 122 via an RF connection between the third capacitor 908 and point 122. Additionally, RF signals 920 and 930 are communicated between the fourth capacitor 910 and terminal E3 via an RF connection between the fourth capacitor 910 and terminal E3.

[0180] 9B is a diagram of an embodiment of a system 950 to illustrate a method for providing low frequencies to multiple RF coils 114 and 902 and providing low and high frequencies to RF coil 904. System 950 includes LFMPS 102, first filter 106, first capacitor 110, HFMPS 104, second filter 108, second capacitor 112, a signal splitter 952, and RF coils 114 and 902. Signal splitter 952 includes a third capacitor 954 and a fourth capacitor 956.

[0181] The first capacitor 110 is coupled to the capacitors 954 and 956 via a split point 958. As an example, the first capacitor 110 is coupled to the capacitors 954 and 956 via a split RF connection, such as a single RF strap split into two RF straps. In this example, the single RF strap is split at the split point 958. The fourth capacitor 956 is coupled to a point 960, and the third capacitor 954 is coupled to the end E1 of the RF coil 114. For example, the fourth capacitor 956 is coupled to the point 960 via an RF connection, and the third capacitor 954 is coupled to the end E1 via an RF connection. Also, the second capacitor 112 is coupled to the point 960. The point 960 is coupled to the end E3 of the RF coil 904 via an RF connection 972.

[0182] The first capacitor 110 receives the filtered signal 118A and balances the reactance of the first filter 106 with the combined reactance of the RF coils 114 and 904 to provide the output RF signal 951. As an example, the first capacitor 110 has a capacitance that achieves a first reactance of the first filter 106 and a second reactance that is the combined reactance of the RF coils 114 and 904. In this example, the first reactance is within a predetermined range from the amplitude of the second reactance and has an amplitude in an opposite direction to that of the second reactance. In this example, the capacitance of the first capacitor 110 reduces the low-frequency resonant frequency of the LFMPS 102. As another example, the first capacitor 110 has a capacitance that cancels the reactance of the first filter 106 against the combined reactance of the RF coils 114 and 904. Illustratively, the first capacitor 110 has a capacitance that achieves a first reactance of the first filter 106 and a second reactance that is the combined reactance of the RF coils 114 and 904. In this illustration, the first reactance is equal in magnitude and opposite in direction to the second reactance. In this illustration, the capacitance of the first capacitor 110 lowers the low frequency resonant frequency of the LFMPS 102. An output RF signal 951 is provided from the first capacitor 110 to a point 958.

[0183] The output RF signal 951 is split at point 958 into an output RF signal 962 and an output RF signal 964. The third capacitor 954 modifies the impedance of the output RF signal 962 to provide an output RF signal 966. For example, the third capacitor 954 balances the reactance of the first filter 106 with the reactance of the RF coil 114 to provide the output RF signal 966. Illustratively, the third capacitor 954 has a capacitance that achieves a first reactance of the first filter 106 and a second reactance of the RF coil 114. In this illustration, the first reactance is within a predetermined range from the magnitude of the second reactance and has an amplitude in an opposite direction to that of the second reactance. In this illustration, the capacitance of the third capacitor 908 reduces the low frequency resonant frequency of the LFMPS 102. As another example, the third capacitor 954 has a capacitance that cancels the reactance of the first filter 106 with respect to the reactance of the RF coil 114. By way of example, the third capacitor 954 has a capacitance that achieves a first reactance of the first filter 106 and a second reactance of the RF coil 114. In this example, the first reactance is equal in magnitude and opposite in direction to the second reactance. In this example, the capacitance of the third capacitor 954 lowers the low frequency resonant frequency of the LFMPS 102. The output RF signal 966 is provided from the third capacitor 954 to the RF coil 114.

[0184] Also, the fourth capacitor 956 modifies the impedance of the output RF signal 964 to provide the output RF signal 968. For example, the fourth capacitor 956 balances the reactance of the first filter 106 with respect to the reactance of the RF coil 114 to provide the output RF signal 968. For example, the fourth capacitor 956 has a capacitance that achieves a first reactance of the first filter 106 and a second reactance of the RF coil 114. In this example, the first reactance is within a predetermined range from the amplitude of the second reactance and has an amplitude in a direction opposite to that of the second reactance. In this example, the capacitance of the fourth capacitor 956 reduces the low-frequency resonant frequency of the LFMPS 102. As another example, the fourth capacitor 956 has a capacitance that cancels the reactance of the first filter 106 with respect to the reactance of the RF coil 114. Illustratively, the fourth capacitor 956 has a capacitance that achieves a first reactance of the first filter 106 and a second reactance of the RF coil 114. In this illustration, the first reactance is equal in magnitude and opposite in direction to the second reactance. In this illustration, the capacitance of the fourth capacitor 956 lowers the low frequency resonant frequency of the LFMPS 102. An output RF signal 968 is provided from the fourth capacitor 956 to a point 960.

[0185] Output RF signals 962, 964, 966, and 968 have a low frequency. Output RF signal 120B has a high frequency.

[0186] Output RF signal 968 is combined, such as by being added, with output RF signal 120B to generate a combined RF signal 970 at point 960. Combined RF signal 970 has a combination of the low frequency of output RF signal 968 and the high frequency of output RF signal 120B. Combined RF signal 970 is communicated to end E3 of RF coil 904 via RF connection 972. Output RF signal 966 is also communicated from third capacitor 954 to end E1 of RF coil 114.

[0187] When the composite RF signal 970 is provided to the RF coil 904 and the output RF signal 966 is provided to the RF coil 114, a plasma is generated or maintained in the plasma chamber including the RF coils 114 and 904. When the plasma is generated or maintained in the plasma chamber, RF power is reflected from the plasma chamber in the form of a reflected RF signal 974. The reflected RF signal 974 is transmitted to a point 960 via the RF coil 904, end E3, and RF connection 972. The reflected RF signal 974 is split at the point 960 into a reflected RF signal 124A and a reflected RF signal 976. The reflected RF signal 124A is provided from the point 960 to the second capacitor 112. The reflected RF signal 976 is provided from the point 960 to a fourth capacitor 956. The fourth capacitor 956 modifies the impedance of the reflected RF signal 976 to provide an RF signal 978 at its input. For example, the fourth capacitor 956 balances the reactance of the first filter 106 and the RF coil 904 in a manner similar to that described above to provide the RF signal 978 to the split point 958. Illustratively, the fourth capacitor 956 reduces the impedance of the reflected RF signal 976 to a minimal amount, such as to zero or close to zero, to output the RF signal 978 to the split point 958.

[0188] Also, when a plasma is generated or maintained in the plasma chamber, RF power is reflected from the plasma chamber in the form of a reflected RF signal 980. The reflected RF signal 980 is transmitted to the third capacitor 954 via the RF coil 114 and the end E1. The third capacitor 954 modifies the impedance of the reflected RF signal 980 to output an RF signal 982 at its input. For example, the third capacitor 954 balances the reactance of the first filter 106 and the RF coil 114 in a manner similar to that described above to provide the RF signal 982 to the split point 958. By way of example, the third capacitor 954 reduces the impedance of the reflected RF signal 980 to a minimal amount, such as zero or close to zero, to output the RF signal 982 to the split point 958. The RF signals 982 and 978 are combined at the split point 958 to generate the reflected RF signal 124B. The reflected RF signal 124B is reflected from the split point 958 toward the first capacitor 110.

[0189] In one embodiment, the first capacitor 110 is coupled to the division point 958 via an RF connection. The division point 958 is also coupled to the third capacitor 954 via an RF connection, and the division point 958 is coupled to the fourth capacitor 956 via an RF connection. The third capacitor 954 is also coupled to the end E1 via an RF connection, and the fourth capacitor 956 is also coupled to a point 960 via an RF connection. The second capacitor 112 is also coupled to the point 960 via an RF connection. In this embodiment, the RF signals 951 and 124B are communicated between the first capacitor 110 and the division point 958 via the RF connection between the first capacitor 110 and the division point 958. The RF signals 962 and 982 are communicated between the division point 958 and the third capacitor 954 via the RF connection between the division point 958 and the third capacitor 954. Additionally, RF signals 966 and 980 are communicated between the third capacitor 954 and the end E1 via an RF connection between the third capacitor 954 and the end E1. Also, RF signals 964 and 978 are communicated between the division point 958 and the fourth capacitor 956 via an RF connection between the division point 958 and the fourth capacitor 956. Additionally, RF signals 968 and 976 are communicated between the fourth capacitor 956 and the point 960 via an RF connection between the fourth capacitor 956 and the point 960. Also, RF signals 120B and 124A are communicated between the point 960 and the second capacitor 112 via an RF connection between the point 960 and the second capacitor 112.

[0190] 9C is a diagram of an embodiment of a plasma system 980 to illustrate a method for filtering low frequencies from being applied to the RF coil 904. The plasma system 980 is similar in structure and function to the plasma system 900 (FIG. 9A) except that the plasma system 980 uses a filter 983. Examples of the filter 983 include the high pass filter 230 (FIG. 2B), the band pass filter 250 (FIG. 2C), and the band pass filter 270 (FIG. 2D).

[0191] The filter 983 is coupled between the capacitor 910 and the RF coil 904. For example, one end of the filter 983 is coupled to the capacitor 910 and the opposite end of the filter 983 is coupled to the end E3 of the RF coil 904.

[0192] If the output signal 920 includes low frequencies, the filter 983 receives the output RF signal 920 from the capacitor 910, filters out the low frequencies, and outputs a filtered signal 984. As an example, the low frequencies are embedded in the output signal 920 when received by the filter 983 from the LFMPS 102 via the filter 106, the capacitor 110, the point 122, the capacitor 908, the split point 912, and the capacitor 910. The filtered signal 984 is provided to the RF coil 904. In this manner, the RF coil 904 is not damaged by the low frequencies.

[0193] A plasma is generated in a plasma chamber including RF coils 114 and 904 when the combined RF signal 922 is provided to RF coil 114 and the filtered signal 984 is provided to RF coil 904. When the plasma is generated, RF power from the plasma is reflected towards filter 983 in the form of reflected RF signal 986. Filter 983 passes high frequencies of reflected RF signal 986 and filters out low frequencies of reflected RF signal 986 to output reflected RF signal 930. Reflected RF signal 930 is transmitted from filter 983 to capacitor 910.

[0194] 9D is a diagram of an embodiment of a plasma system 990 to illustrate a method for filtering high frequency waves from being applied to the RF coil 114. The plasma system 990 is similar in structure and function to the plasma system 950 (FIG. 9B) except that the plasma system 990 uses a filter 992. Examples of the filter 992 include the low pass filter 200 (FIG. 2A), the band pass filter 250 (FIG. 2C), and the band pass filter 270 (FIG. 2D).

[0195] The filter 992 is coupled between the capacitor 954 and the RF coil 114. For example, one end of the filter 992 is coupled to the capacitor 954 and the opposite end of the filter 992 is coupled to the end E1 of the RF coil 114.

[0196] If the output RF signal 966 includes high frequencies, the filter 992 receives the output RF signal 966 from the capacitor 954, filters out the high frequencies, and outputs a filtered signal 994. As an example, the high frequencies are embedded in the output RF signal 966 when received by the filter 992 from the HFMPS 104 via the second filter 108, the second capacitor 112, the point 960, the capacitor 956, the split point 958, and the capacitor 954. The filtered signal 994 is provided to the RF coil 114. In this manner, the RF coil 114 is not damaged by the high frequencies.

[0197] A plasma is generated in a plasma chamber including RF coils 114 and 904 when the composite RF signal 970 is provided to RF coil 904 and the filtered signal 994 is provided to RF coil 114. When the plasma is generated, RF power from the plasma is reflected towards filter 992 in the form of reflected RF signal 996. Filter 992 passes low frequencies of reflected RF signal 996 and filters out high frequencies of reflected RF signal 996 to output reflected RF signal 980. Reflected RF signal 980 is transmitted from filter 992 to capacitor 954.

[0198] 10A is a diagram of an embodiment of a plasma system 1000 to illustrate the use of a signal splitter 906 in the plasma system 1000. The plasma system 1000 includes an LFMPS 102, a first filter 106, a first capacitor 110, an HFMPS 104, a second filter 108, a second capacitor 112, a signal splitter 906, an LF bias RFG 302, an HF bias RFG 304, a matching box 306, and a plasma chamber 1002. The plasma chamber 1002 is similar in structure to the plasma chamber 308 (FIG. 3A) except that the plasma chamber 1002 includes an RF coil 1004.

[0199] The RF coil 1004 is in the periphery of the RF coil 312. For example, the RF coil 1004 surrounds the RF coil 312 and is disposed in the same horizontal plane as the RF coil 312. The RF coil 1004 is an example of the RF coil 904 (FIG. 9A). The capacitor 910 is coupled to an end E3 of the RF coil 1004.

[0200] A plasma is generated in the plasma chamber 1002 when the composite RF signal 922 is provided to the RF coil 312, the output RF signal 920 is provided to the RF coil 1004, the modified RF signal 334 is provided to the lower electrode 311, and one or more process gases are provided to the plasma chamber 1002. RF power of the plasma is reflected in the form of reflected RF signals 930 and 924.

[0201] In one embodiment, RF coil 1004 is disposed in a different horizontal plane than the horizontal plane in which RF coil 302 is disposed.

[0202] 10B is a diagram of an embodiment of a plasma system 1020 having a plasma chamber 1002 with a lower electrode 311 coupled to ground potential to illustrate the use of a signal splitter 906. The plasma system 1020 includes a LFMPS 102, a first filter 106, a first capacitor 110, a HFMPS 104, a second filter 108, a second capacitor 112, a signal splitter 906, and a plasma chamber 1002.

[0203] A plasma is generated in the plasma chamber 1002 when the composite RF signal 922 is provided to the RF coil 312, the output RF signal 920 is provided to the RF coil 1004, the lower electrode 311 is coupled to ground potential, and one or more process gases are provided to the plasma chamber 1002. The RF power of the plasma is reflected in the form of reflected RF signals 930 and 924.

[0204] 10C is a diagram of an embodiment of a plasma system 1040 to illustrate the use of a signal splitter in the plasma system 1040. The plasma system 1040 includes an LFMPS 102, a first filter 106, a first capacitor 110, an HFMPS 104, a second filter 108, a second capacitor 112, a signal splitter 952, an LF bias RFG 302, an HF bias RFG 304, a matching box 306, and a plasma chamber 1002. A point 960 is coupled to an end E3 of an RF coil 1004.

[0205] A plasma is generated in the plasma chamber 1002 when the composite RF signal 970 is provided to the RF coil 1004, the output RF signal 966 is provided to the RF coil 312, the modified RF signal 334 is provided to the lower electrode 311, and one or more process gases are provided to the plasma chamber 1002. RF power of the plasma is reflected in the form of reflected RF signals 974 and 980.

[0206] 10D is a diagram of an embodiment of a plasma system 1050 having a plasma chamber 1002 with a lower electrode 311 coupled to ground potential to illustrate the use of a signal splitter 952. The plasma system 1050 includes a LFMPS 102, a first filter 106, a first capacitor 110, a HFMPS 104, a second filter 108, a second capacitor 112, a signal splitter 952, and a plasma chamber 1002.

[0207] A plasma is generated in the plasma chamber 1002 when the composite RF signal 970 is provided to the RF coil 1004, the output RF signal 966 is provided to the RF coil 312, the lower electrode 311 is coupled to ground potential, and one or more process gases are provided to the plasma chamber 1002. The RF power of the plasma is reflected in the form of reflected RF signals 974 and 980.

[0208] FIG. 11A is an embodiment of a graph 1100 to illustrate a clock signal 1102. In the graph 1100, the logic levels of the clock signal 1102 are plotted against time t. The clock signal 1102 transitions periodically between logic level 1 and logic level 0. For example, during cycle 1 of the clock signal 1102, at time t0, the clock signal 1102 transitions from logic level 0 to logic level 1. During cycle 1, the clock signal 1102 remains at logic level 1 from time t0 to time t8. Further, during cycle 1, at time t8, the clock signal 1102 transitions from logic level 1 to logic level 0. The clock signal 1102 remains at logic level 0 from time t8 to time t16. During cycle 2 of the clock signal 1102, at time t16, the clock signal 1102 transitions from logic level 0 to logic level 1. Cycle 2 is consecutive to cycle 1. During cycle 2, clock signal 1102 remains at logic level 1 from time t16 to time t24. Further, during cycle 1, at time t24, clock signal 1102 transitions from logic level 1 to logic level 0. Clock signal 1102 remains at logic level 0 from time t24 to time t32. In this manner, the logic levels 0 and 1 of clock signal 1102 are periodically repeated during additional cycles of clock signal 1102.

[0209] FIG. 11B is an embodiment of a graph 1104 for illustrating a parameter, such as power or voltage, of an RF signal 1106 generated by the LFMPS 102 (FIG. 1) or the LF bias RFG 302 (FIG. 3A) or the LF source RFG 402 (FIG. 4). The RF signal 1106 is an example of the RF signal 116A (FIG. 1) or the RF signal 330 (FIG. 3A) or the RF signal 420 (FIG. 4). The RF signal 1106 is a continuous wave (CW) signal, such as a sinusoidal signal, having peak-to-peak parameter levels of PR2 and -PR2, or a zero-to-peak amplitude of PR2. For example, the RF signal 1106 oscillates periodically between parameter levels PR2 and -PR2 during each clock cycle of the clock signal 1102. The parameter level PR2 is greater than the parameter level PR0, which is greater than the parameter level -PR2.

[0210] FIG. 11C is an embodiment of a graph 1108 for illustrating a parameter of an RF signal 1110 generated by the HFMPS 104 (FIG. 1) or the HF bias RFG 304 (FIG. 3A) or the HF source RFG 404 (FIG. 4). The graph 1108 plots the parameter of the RF signal 1110 on the Y-axis and time t on the X-axis. The RF signal 1110 is an example of the RF signal 116B (FIG. 1) or the RF signal 332 (FIG. 3A) or the RF signal 422 (FIG. 4). The RF signal 1110 is a continuous wave signal and has peak-to-peak parameter levels of PRb and -PRb, or a zero-to-peak amplitude of PRb. For example, the RF signal 1110 oscillates periodically between parameter levels PRb and -PRb during each clock cycle of the clock signal 1102. The parameter level PRb is greater than the parameter level PR0, which is greater than the parameter level -PRb. As an example, parameter level PRb is lower than parameter level PR2 and parameter level -PRb is higher than parameter level -PR2. As another example, parameter level PR2 is lower than parameter level PRb and parameter level -PR2 is higher than parameter level -PRb.

[0211] It should be noted that the frequency of oscillation of RF signal 1110 is greater than the frequency of oscillation of RF signal 1106. Therefore, RF signal 1110 has a higher frequency than RF signal 1106.

[0212] FIG. 11D is an embodiment of a graph 1112 to illustrate an RF signal 1114 pulsed between parameter levels PR2 and -PR2 and parameter levels PR1 and -PR1. In the graph 1112, the parameters of the RF signal 1114 are plotted on the Y-axis and time t on the X-axis. The parameter levels PR2 and -PR2 represent a state S1 of the parameter of the RF signal 1114. Also, the parameter levels PR1 and -PR1 represent a state S2 of the parameter of the RF signal 1114. The parameter level PR1 is lower than the parameter level PR2 and higher than the parameter level PR0. Similarly, the parameter level -PR1 is higher than the parameter level -PR2 and lower than the parameter level PR0. The RF signal 1114 is an example of the RF signal 116A (FIG. 1) or the RF signal 330 (FIG. 3A) or the RF signal 420 (FIG. 4).

[0213] During cycle 1 of the clock signal 1102, at time t0, a parameter of the RF signal 1114 is pulsed, transitioning from parameter level PR1 to parameter level PR2, and from parameter level -PR1 to parameter level -PR2, etc. The RF signal 1114 oscillates between parameter levels PR2 and -PR2 from time t0 to time t8. Also, the peak-to-peak parameter levels of the RF signal 1114 from time t0 to time t8 are PR2 and -PR2.

[0214] Additionally, during cycle 1 of the clock signal 1102, at time t8, a parameter of the RF signal 1114 is pulsed from parameter level PR2 to parameter level PR1, and from parameter level -PR2 to parameter level -PR1. The RF signal 1114 oscillates between parameter levels PR1 and -PR1 from time t8 to time t16. Also, the peak-to-peak parameter levels of the RF signal 1114 from time t8 to time t16 are parameter levels PR1 and -PR1. In a similar manner, parameter levels PR2 and -PR2, and parameter levels PR1 and -PR1 are repeated during cycle 2 of the clock signal 1102.

[0215] FIG. 11E is an embodiment of a graph 1116 to illustrate an RF signal 1118 pulsed between parameter levels PRb and PRa, and between parameter levels -PRb and -PRa. In the graph 1116, the parameters of the RF signal 1118 are plotted on the Y-axis and time t on the X-axis. The parameter levels PRb and -PRb represent a state S1 of the parameter of the RF signal 1118. Also, the parameter levels PRa and -PRa represent a state S2 of the parameter of the RF signal 1118. The parameter level PRa is lower than the parameter level PRb and higher than the parameter level PR0. Similarly, the parameter level -PRa is higher than the parameter level -PRb and lower than the parameter level PR0. The RF signal 1118 is an example of the RF signal 116B (FIG. 1) or the RF signal 332 (FIG. 3A) or the RF signal 422 (FIG. 4).

[0216] During cycle 1 of clock signal 1102, at time t0, a parameter of RF signal 1118 is pulsed from parameter level PRa to parameter level PRb, and from parameter level -PRa to parameter level -PRb. RF signal 1118 oscillates between parameter levels PRb and -PRb from time t0 to time t8.

[0217] Additionally, during cycle 1 of the clock signal 1102, at time t8, the parameter of the RF signal 1118 is pulsed from parameter level PRb to parameter level PRa, and from parameter level -PRb to parameter level -PRa. The RF signal 1118 oscillates between parameter levels PRa and -PRa from time t8 to time t16. Also, the peak-to-peak parameter levels of the RF signal 1118 from time t8 to time t16 are PRa and -PRa. In a similar manner, the parameter levels PRb and -PRb, and parameter levels PRa and -PRa are repeated during cycle 2 of the clock signal 1102. Note that the frequency of oscillation of the RF signal 1118 is greater than the frequency of oscillation of the RF signal 1114.

[0218] FIG. 11F is an embodiment of a graph 1112 of an RF signal 1114.

[0219] 11G is an embodiment of a graph 1120 to illustrate a pulsed RF signal 1122 out of phase with the pulsed RF signal 1114 (FIG. 11F). In the graph 1120, a parameter of the RF signal 1122 is plotted versus time t. The RF signal 1122 is an example of the RF signal 116B (FIG. 1) or the RF signal 332 (FIG. 3A) or the RF signal 422 (FIG. 4).

[0220] During cycle 1 of the clock signal 1102, from time t0 to time t2, the parameter of the RF signal 1122 is pulsed between parameter levels PRa and -PRa. Additionally, during cycle 1 of the clock signal 1102, at time t2, the parameter of the RF signal 1122 is pulsed from parameter level PRa to parameter level PRb, and from parameter level -PRa to parameter level -PRb. The parameter levels PRa and -PRa represent a state S1 of the parameter of the RF signal 1122. Additionally, the parameter levels PRb and -PRb represent a state S2 of the parameter of the RF signal 1122. Time t2 occurs after time t0. During cycle 1 of the clock signal 1102, from time t2 to time t10, the parameter of the RF signal 1122 is pulsed between parameter levels PRb and -PRb. Time t10 occurs after time t8.

[0221] Also during cycle 1 of clock signal 1102, at time t10, a parameter of RF signal 1122 is pulsed from parameter level PRb to parameter level PRa, and from parameter level -PRb to parameter level -PRa. RF signal 1122 oscillates between parameter levels PRa and -PRa from time t10 to time t16. In a similar manner, parameter levels PRa and -PRa, and parameter levels PRb and -PRb, are repeated during cycle 2 of clock signal 1102. Note that the frequency of oscillation of RF signal 1122 is greater than the frequency of oscillation of RF signal 1114.

[0222] Parameter levels PRb and PRa of RF signal 1122 are pulsed out of phase with the pulsed parameter levels PR2 and PR1 of RF signal 1114, and parameter levels -PRb and -PRa of RF signal 1122 are pulsed out of phase with the pulsed parameter levels -PR2 and -PR1 of RF signal 1114. As an example, rather than transitioning from parameter level PRa to parameter level PRb at time t0 during cycle 1 of clock signal 1102 (FIG. 11A), the parameter of RF signal 1122 transitions from parameter level PRa to parameter level PRb at time t2. As another example, rather than transitioning from parameter level PRb to parameter level PRa at time t8 during cycle 1 of clock signal 1102 (FIG. 11A), the parameter of RF signal 1122 transitions from parameter level PRb to parameter level PRa at time t10. As yet another example, during cycle 2 of the clock signal 1102, rather than transitioning from parameter level PRa to parameter level PRb at time t16, the parameter of the RF signal 1122 transitions from parameter level PRa to parameter level PRb at time t18, which occurs after time t16.

[0223] In one embodiment, the parameter of the RF signal transitions from parameter level PRb to parameter level PRa at time t6 instead of time t10, similar to RF signal 1122. Time t6 occurs before time t8. Also, the parameter of the RF signal transitions from parameter level PRa to parameter level PRb at time t14 instead of time t18, similar to RF signal 1122. Time t14 occurs before time t16.

[0224] FIG. 11H is an embodiment of a graph 1112 of an RF signal 1114.

[0225] 11I is an embodiment of a graph 1124 to illustrate that the pulse output frequency of a parameter of RF signal 1114 (FIG. 11F) is lower than the pulse output frequency of a parameter of RF signal 1126. In graph 1124, a parameter of RF signal 1126 is plotted versus time t. RF signal 1126 is an example of RF signal 116B (FIG. 1) or RF signal 332 (FIG. 3A) or RF signal 422 (FIG. 4).

[0226] During cycle 1 of the clock signal 1102, at time t0, a parameter of the RF signal 1126 is pulsed from parameter level PRa to parameter level PRb and from parameter level -PRa to parameter level -PRb. The parameter levels PRb and -PRb represent a state S1 of the parameter of the RF signal 1126. Also, the parameter levels PRa and -PRa represent a state S2 of the parameter of the RF signal 1126. The parameter levels of the RF signal 1126 from time t0 to time t16 are PRb and -PRb. For example, the RF signal 1126 oscillates between parameter levels PRb and -PRb from time t0 to time t16.

[0227] Furthermore, during cycle 2 of the clock signal 1102, at time t16, the parameter of the RF signal 1126 is pulsed from parameter level PRb to parameter level PRa, and from parameter level -PRb to parameter level -PRa. During cycle 2 of the clock signal 1102, from time t16 to time t32, the parameter levels of the RF signal 1126 are PRa and -PRa. For example, the RF signal 1126 oscillates between parameter levels PRa and -PRa from time t16 to time t32. Time t32 occurs after time t16. In a similar manner, the parameter levels PRa and -PRa, and the parameter levels PRb and -PRb are repeated during cycle 3 of the clock signal 1102. Cycle 3 is consecutive to cycle 2 of the clock signal 1102. Note that the frequency of oscillation of the RF signal 1126 is greater than the frequency of oscillation of the RF signal 1114.

[0228] The parameter levels PR2, -PR2, PR1, and -PR1 of the RF signal 1114 have a greater pulse output frequency than the parameter levels PRb, -PRb, PRa, and -PRa of the RF signal 1126. As an example, during cycle 1 of the clock signal 1102 (FIG. 11A), the parameters of the RF signal 1114 are pulsed twice and the parameter levels of the RF signal 1126 are pulsed once. By way of example, during cycle 1 of the clock signal 1102, the parameters of the RF signal 1114 are pulsed at time t0 for the first instance and at time t8 for the second instance. In this example, during cycle 1 of the clock signal 1102, the parameters of the RF signal 1126 are pulsed once at time t0. In this way, during each cycle of the clock signal 1102, the parameters of the RF signal 1114 are pulsed at a greater pulse output frequency than the parameters of the RF signal 1126.

[0229] Also, the duty cycle of the pulsed output of the parameter of RF signal 1114 is different from the duty cycle of the pulsed output of the parameter of RF signal 1126. For example, the duty cycle of the pulsed output of the parameter of RF signal 1114 is 50% and the duty cycle of the pulsed output of the parameter of RF signal 1126 is 100%. To illustrate, the parameter level of RF signal 1114 is PR2 for half the period of each clock cycle of clock signal 1102 (FIG. 11A). In this example, the parameter level of RF signal 1126 is PRb for the full period of each clock cycle of clock signal 1102.

[0230] In one embodiment, the parameter of another RF signal similar to RF signal 1126 has a pulse frequency greater than the pulse frequency of the parameter of RF signal 1114. For example, the parameter of the other RF signal is pulsed three times during each cycle of clock signal 1102. Illustratively, the parameter of the other RF signal is pulsed from parameter level PRa to parameter level PRb at time t0, pulsed from parameter level PRb to parameter level PRa at time t4, and pulsed from parameter level PRa to parameter level PRb at time t8. Time t4 occurs after time t0 and before time t8.

[0231] It should be noted that the pulsing of the parameters of the RF signal described herein between a set of positive parameter levels (e.g., from PRa to PRb, or vice versa) occurs synchronously with the pulsing of the parameters of the RF signal between a set of negative parameter levels (e.g., from -PRa to -PRb, or vice versa). For example, the parameters of the RF signal 1114 transition from parameter level PR1 to parameter level PR2 at time t0. In this example, the parameters of the RF signal 1114 transition simultaneously from parameter level -PR1 to parameter level -PR2 at time t0. As another example, the parameters of the RF signal 1114 transition from parameter level PR2 to parameter level PR1 at time t8. In this example, the parameters of the RF signal 1114 transition simultaneously from parameter level -PR2 to parameter level -PR1 at time t8.

[0232] FIG. 12A-1 is a diagram of an embodiment of a system 1200 to illustrate details of an MPS 1202. The MPS 1202 is an example of either the LFMPS 102 or the HFMPS 104 (FIG. 1). The system 1200 includes the MPS 1202 and a host computer 1204. The host computer 1204 includes a processor 1206 and a memory device 1208. The processor 1206 is coupled to the memory device 1208. Examples of processors used herein include application specific integrated circuits (ASICs), programmable logic devices (PLDs), microprocessors, microcontrollers, central processing units (CPUs), and the like. Examples of memory devices used include random access memory (RAM) and read only memory (ROM). Illustratively, the memory device is a flash memory, or a redundant array of independent disks (RAID).

[0233] The MPS 1202 includes an input section 1210, an output section 1212, and a reactance circuit 1214. Examples of the input section 1210 include a signal generator and a part of a gate driver. An example of a signal generator is a square wave oscillator that generates a square wave signal, such as a digital waveform or a pulse train. The square wave signal may be referred to as a square waveform herein. The square waveform is pulsed between a first logic level (e.g., high or 1) and a second logic level (e.g., low or zero). Examples of the output section 1212 include the rest of the gate driver and a half-bridge transistor circuit. Additionally, an example of the reactance circuit 1214 includes a variable capacitor. Another example of the reactance circuit 1214 includes a fixed capacitor.

[0234] The input 1210 is coupled to the output 1212, which is coupled to the reactance circuit 1214. The reactance circuit 1214 is coupled to the filter 1218 via an RF connection 1510. The filter 1218 is an example of any of the filters 106 and 108 (FIG. 1). For example, if the MPS 1202 is an example of the LFMPS 102, the filter 1218 is an example of the first filter 106. In this example, if the MPS 1202 is an example of the LFMPS 104, the filter 1218 is an example of the second filter 108. The processor 1206 is coupled to the input 1210 via a transfer cable 1226. Examples of transfer cables as used herein include cables that transfer data in a serial manner, or in a parallel manner, or via a Universal Serial Bus (USB) protocol.

[0235] The processor 1206 generates a recipe signal 1224. The recipe signal 1224 includes one or more parameter levels of a parameter of the RF signal 1222 output from the MPS 1202. The recipe signal 1224 further includes a frequency of the RF signal 1222. For example, the recipe signal 1224 includes an operating frequency of the MPS 1202. The recipe signal 1224 also includes one or more transition times. For example, if the recipe signal 1224 indicates that two parameter levels of the RF signal 1222 are achieved during each cycle of the clock signal 1102 (FIG. 11A), the recipe signal 1224 further includes a time for a transition from a first one of the parameter levels to a second one of the parameter levels and a time for a transition from the second one of the parameter levels to the first one of the parameter levels. The recipe signal 1224 is transmitted from the processor 1206 to the input 1210 via a transfer cable 1226.

[0236] In response to receiving the recipe signal 1224, the input 1210 generates a plurality of square wave signals and provides the square wave signals to the output 1212. Each of the square wave signals has a frequency received in the recipe signal 1224. The output 1212 generates an amplified square waveform based on the plurality of square wave signals received from the input 1210. Furthermore, the output 1212 shapes an envelope, such as a peak-to-peak magnitude or a zero-to-peak magnitude, of the amplified square waveform. For example, a shaping control signal 1220 is provided from the input 1210 to the output 1212 to generate the envelope. As an example, the input 1210 generates the shaping control signal 1220 based on one or more parameter levels and one or more transition times received in the recipe signal 1224. The shaping control signal 1220 has a plurality of voltage values ​​for shaping the amplified square waveform. For example, a first voltage value shapes the amplified square waveform to have a first parameter level, and a second voltage value shapes the amplified square waveform to have a second parameter level.

[0237] The shaped amplified rectangular waveform is transmitted from the output 1212 to a reactance circuit 1214. The reactance circuit 1214 filters out or otherwise removes higher order harmonics of the amplified rectangular waveform to generate an RF signal 1222, which is a shaped sinusoidal waveform having a fundamental frequency. The fundamental frequency is a frequency received from the recipe signal 1224. The RF signal 1222 is an example of an RF signal 116A or 116B. For example, if the MPS 1202 is an example of an LFMPS 102, then the RF signal 1222 is an example of an RF signal 116A. In this example, if the MPS 1202 is an example of an LFMPS 104, then the RF signal 1222 is an example of an RF signal 116B. The shaped sinusoidal waveform has an envelope having a shape, such as a digital pulse shape, a continuous wave shape, an arbitrary pulse shape, a multi-level pulse shape, etc. The multi-level pulse shape has multiple parameter levels of the RF signal 1222.

[0238] The RF signal 1222 is transmitted from the reactance circuit 1214 via connection 1216 to the filter 1218. An example of an MPS 1202 is described in U.S. Patent No. 10,264,663, which is incorporated herein by reference in its entirety.

[0239] In some embodiments, the input section 1210 includes a controller board having a signal generator and further includes a gate driver, and the output section includes a half-bridge transistor circuit. The controller board includes a controller coupled to the signal generator to control the signal generator to generate a square wave signal at a predetermined frequency (e.g., high frequency or low frequency, etc.).

[0240] 12A-2 is a diagram of one embodiment of a system 1250 to illustrate further details of the input section 1210 and the output section 1212. The input section 1210 includes a controller 1252, a signal generator 1254, and a gate driver system 1256. The output section includes a FET circuit 1258, a direct current (DC) voltage source 1262, and a field effect transistor (FET) circuit 1258. Examples of controllers as used herein include a combination of a processor and a memory device, where the processor is coupled to the memory device.

[0241] An example of the signal generator 1254 is a square wave oscillator, which generates a square wave signal (e.g., a square wave signal that is a digital waveform or a pulse train). The square waveform pulses periodically and has square pulses. For example, the square waveform transitions between a first logic level (e.g., high or 1) and a second logic level (e.g., low or zero) during each cycle of the clock signal 1102 (FIG. 11A). The signal generator 306 generates the square wave signal at a high or low frequency. An example of the gate driver system 1256 includes a combination of a first gate driver, a second gate driver, and a NOT gate. The second gate driver is coupled to the NOT gate. An example of the FET circuit 1258 is a half-bridge FET circuit. Illustratively, the half-bridge FET circuit has a first transistor and a second transistor, and the first transistor and the second transistor are both coupled to each other. To further illustrate, the drain of the first transistor is coupled to a DC voltage source 1262, the source of the first transistor is coupled to a drain of the second transistor, and the source of the second transistor is coupled to ground potential. Additionally, a first gate driver of the gate driver system 1256 is coupled to a gate of the first transistor, and a NOT gate of the gate driver system 1256 is coupled to a gate of the second transistor. The output of the FET circuit 1258 is between the source of the first transistor and the drain of the second transistor.

[0242] The processor 1206 is coupled to a controller 1252 via a transfer cable 1226. The controller 1252 is coupled to a signal generator 1254. The signal generator 1254 is coupled to inputs of a first and a second gate driver of a gate driver system 1256. An output of the first gate driver and an output of the NOT gate are coupled to a FET circuit 1258. The FET circuit 1258 is coupled to a DC voltage source 1262 and the reactance circuit 1214.

[0243] The controller 1252 receives the recipe signal 1224 from the processor 1206 via the transfer cable 1226. Upon receiving the recipe signal 1224, the controller 1252 determines the frequency of the RF signal 1222 generated by the MPS 1202 and determines one or more parameter levels and one or more transition times between the parameter levels from the recipe signal 1224. The processor 1206 generates a trigger signal (e.g., an on-command signal, etc.) and provides the trigger signal to the controller 1252 via the transfer cable 1226. For example, the processor 1206 transmits the trigger signal to the controller 1252 after a predetermined time. By way of example, the processor 1206 transmits the trigger signal to the controller 1252 of the LFMPS 102 (FIG. 1) after a predetermined time after the trigger signal is transmitted to the controller 1252 of the HFMPS 104 (FIG. 1). The LFMPS 102 and the HFMPS 104 are turned off until the trigger signal is received.

[0244] Upon receiving the trigger signal, the controller 1252 provides a frequency to the signal generator 1254. Also upon receiving the trigger signal, the controller 1252 generates a shaped control signal 1220 based on the one or more parameter levels and the one or more transition times. The controller 1252 provides the shaped control signal 1220 to a DC voltage source 1262.

[0245] Upon receiving the frequency, the signal generator 1254 generates a square wave signal 1264 and provides the square wave signal 1264 to a gate driver of the gate driver system 1256. A first gate driver of the gate driver system 1256 amplifies a parameter of the square wave signal 1264 to output a first amplified square wave signal 1266. A second gate driver of the gate driver system 1256 amplifies a parameter of the square wave signal 1264 to output a second amplified square wave signal and provides the second amplified square wave signal to a NOT gate. The NOT gate inverts the second amplified square wave signal to output an inverted signal 1268, which is also a square wave signal.

[0246] Signals 1266 and 1268 are provided to the gate of FET circuit 1258. A first transistor in FET circuit 1258 is turned on and off according to the first amplified square wave signal 1266, and a second transistor in FET circuit 1258 is turned on and off according to the inverted signal 1268 to provide an amplified square wave signal 1272 at the output of FET circuit 1258.

[0247] Upon receiving the shaped control signal 1220, the DC voltage source 1262 provides a voltage signal 1270 to the FET circuit 1258. The voltage signal 1270 has a voltage level that is pulsed according to one or more transition times indicated by the shaped control signal 1220. Furthermore, the voltage signal 1270 has one or more voltage levels that are generated based on one or more parameter levels indicated by the shaped control signal 1220. The parameters of the amplified square wave signal 1272 are pulsed at one or more transition times indicated by the voltage signal 1270 and have one or more parameter levels also indicated by the voltage signal 1270. The reactance circuit receives the amplified square wave signal 1272 and removes harmonics from the amplified square wave signal 1272 to output an RF signal 1222 having a fundamental frequency (e.g., high frequency or low frequency).

[0248] It should be noted that if the RF signal 1222 is a continuous wave signal, then the recipe signal 1224 includes a single parameter level and does not include transition times. Upon receiving the recipe signal 1224, the controller 1252 generates the shaped control signal 1220 to indicate the single parameter level and no transition times. In response to receiving the shaped control signal 1220, the DC voltage source 1262 generates a voltage signal 1270 having a single voltage level. Upon receiving the single voltage level and signals 1266 and 1268, the FET circuit 1258 outputs an amplified square waveform 1262 having a single parameter level based on the single voltage level.

[0249] When the processor 1206 sends the OFF command signal to the controller 1252 via the transfer cable 1226, the controller 1252 sends an OFF control signal to the signal generator 1254. For example, the processor 1206 sends the OFF command signal to the controller 1252 after a predetermined time. Upon receiving the OFF control signal, the signal generator 1254 stops generating the square wave signal 1264 and the MPS 1202 does not generate the RF signal 1222.

[0250] 12B is a diagram of an embodiment of a system 1280 to illustrate details of the RF generator 1280. The system 1280 includes the host computer 1204 and an RF generator 1282. The RF generator 1282 is an example of any of the LF source RFG 402, HF source RFG 404, LF bias RFG 302, and HF bias RF 304 (FIGS. 3A and 4).

[0251] The RF generator 1282 includes a digital signal processor (DSP) 1284, a parameter controller PRS1, a parameter controller PRS2, a frequency controller FC, a driver DRVR, and a power supply PS. An example of a driver used herein includes one or more transistors. An example of a power supply PS is an oscillator that generates a sinusoidal RF signal.

[0252] The processor 1206 is coupled to the DSP 1284 via a transfer cable 1290. The DSP 1284 is coupled to the parameter controllers PRS1 and PRS2 and to the frequency controller FC. The frequency controller FC and the parameter controllers PRS1 and PRS2 are coupled to the driver DRVR, which is coupled to the power supply PS. The DSP 1284 is coupled to the driver DRVR.

[0253] The processor 1206 generates a recipe signal 1286 and provides the recipe signal 1286 to the DSP 1284 via a transfer cable 1290. As an example, the recipe signal 1286 includes a first parameter level of an RF signal 1288 generated by the RF generator 1282, a second parameter level of the RF signal 1288, and a frequency of the RF signal 1288. The RF signal 1288 is an example of any of the RF signals 330, 332, 420, and 422 (FIGS. 3A and 4). Also, in this example, the first parameter level represents a state S1 of the RF signal 1288, the second parameter level represents a state S2 of the RF signal 1288, and the recipe signal 1286 includes a first transition time of a transition from the second parameter level to the first parameter level and a second transition time of a transition from the first parameter level to the second parameter level during each clock cycle of the clock signal 1102 (FIG. 11A).

[0254] The DSP 1284 receives the recipe signal 1286 from the processor 1206 and identifies a first and a second parameter level from the recipe signal 1286. The DSP 1284 also identifies a first and a second transition time from the recipe signal 1286. The DSP 1284 provides the first parameter level and the first transition time to the parameter controller PRS1 and provides the second parameter level and the second transition time to the parameter controller PRS2. The parameter controller PRS1 stores the first parameter level and the first transition time in a memory device of the parameter controller PRS1, and the parameter controller PRS2 stores the second parameter level and the second transition time in a memory device of the parameter controller PRS2. The DSP 1284 also provides a frequency to the frequency controller FC. The frequency controller FC stores the frequency in a memory device of the frequency controller FC.

[0255] The processor 1206 generates a trigger signal and transmits it to the DSP 1284 via the transmission cable 1290. For example, the processor 1206 transmits the trigger signal to the DSP 1284 after a predetermined time. By way of example, the processor 1206 transmits the trigger signal to the DSP 1284 of the LF source RFG 402 after a predetermined time after the trigger signal is transmitted to the DSP 1284 of the HF source RFG 404.

[0256] Upon receiving a trigger signal (e.g., a digital pulse) from the processor 1206, the DSP 1284 sends the trigger signal to the parameter controllers PRS1 and PRS2 and the frequency controller FC. Upon receiving the trigger signal, the parameter controller PRS1 generates a control signal at a first transition time based on a first parameter level of the state S1 and sends the control signal to the driver DRVR. Also upon receiving the trigger signal, the frequency controller FC generates a control signal and sends the control signal to the driver DRVR. In response to receiving the control signal from the parameter controller PRS1 and the frequency controller FC, the driver generates a drive signal for the state S1 and sends the drive signal to the power supply PS. In response to receiving the drive signal for the state S1, the power supply PS generates a first parameter level of the RF signal 1288 at a first transition time.

[0257] Furthermore, upon receiving the trigger signal, the parameter controller PRS2 generates a control signal at a second transition time based on the second parameter level of the state S2 and transmits the control signal to the driver DRVR. In response to receiving the control signal from the parameter controller PRS2 and the frequency controller FC, the driver generates a drive signal of the state S2 and transmits the drive signal to the power supply PS. In response to receiving the drive signal of the state S2, the power supply PS generates a second parameter level of the RF signal 1288 at a second transition time. In this manner, the parameter of the RF signal 1288 transitions from the second parameter level to the first parameter level at the first transition time and transitions from the first parameter level to the second parameter level at the second transition time.

[0258] When the processor 1206 sends an off command signal to the DSP 1284 via the transmission cable 1290, the DSP 1284 sends an off control signal to the driver DRVR. For example, the processor 1206 sends an off command signal to the DSP 1284 after a predetermined time. Upon receiving the off control signal, the driver DRVR stops sending a drive signal to the power supply PS. When no drive signal is received, the power supply PS turns off and stops generating the RF signal 1288.

[0259] In one embodiment, the separate RF generator is used when the RF signal generated by the RF generator 1282 includes a single parameter level (e.g., a first parameter level). The separate RF generator has the same structure as the RF generator 1282, except that the separate RF generator does not include a parameter controller PRS2. The processor 1206 generates a separate recipe signal and provides the separate recipe signal to the DSP 1284. As an example, the separate recipe signal is similar to the recipe signal 1286, except that the separate recipe signal does not include the first and second transition times and does not include the second parameter level in state S2. The DSP 1284 receives the separate recipe signal from the processor 1206 and identifies the first parameter level from the recipe signal 1286. The DSP 1284 provides the first parameter level to the parameter controller PRS1. The parameter controller PRS1 stores the first parameter level in a memory device of the parameter controller PRS1. Upon receiving a trigger signal from the processor 1206, the DSP 1284 sends the trigger signal to the parameter controller PRS1 and the frequency controller FC. Upon receiving the trigger signal, the parameter controller PRS1 generates a control signal based on the first parameter level of the state S1 and sends the control signal to the driver DRVR. Also upon receiving the trigger signal, the frequency controller FC generates a control signal and sends the control signal to the driver DRVR. In response to receiving the control signal from the parameter controller PRS1 and the frequency controller FC, the driver generates a drive signal for the state S1 and sends the drive signal to the power supply PS. In response to receiving the drive signal for the state S1, the power supply PS generates a first parameter level of the RF signal 1288.

[0260] 13 is a diagram of one embodiment of a system 1300 to illustrate control of a variable capacitor 1306. The system 1300 includes a host computer 1204, a driver 1302, a motor 1304, and a variable capacitor 1306. The variable capacitor 1306 is an example of any of the first capacitor 110, the second capacitor 112, the third capacitor 908 (FIG. 9A), the fourth capacitor 910 (FIG. 9B), the third capacitor 954 (FIG. 9B), and the fourth capacitor 956 (FIG. 9B).

[0261] An example of the motor 1304 is an AC motor including a stator and a rotor. An example of the driver 1302 includes one or more transistors. The processor 1206 is coupled to the driver 1302, which is coupled to the motor 1304, which is coupled to the capacitor 1306. The processor 1206 generates and transmits a control signal based on the capacitance achieved by the capacitor 1306. Upon receiving the control signal, the driver 1302 generates a drive signal (e.g., a current signal, etc.) and transmits the drive signal to the motor 1304. The motor 1304 operates to change the amount of overlap between a first plate and a second plate of the capacitor 1306, thereby changing the capacitance of the capacitor 1306.

[0262] FIG. 14 is a diagram of one embodiment of a plasma chamber 1400 to illustrate a solenoid coil 1402. The plasma chamber 1400 includes a solenoid coil 1402 and a substrate support 310. The solenoid coil 1402 is located above a dielectric window 314 and is wrapped around a dielectric mandrel 1403. The solenoid coil 1402 has an end 1404 and an opposite end 1406. As an example, if the solenoid coil 1402 is used rather than the RF coil 114, the end 1404 is coupled to the point 122 (FIGS. 1, 7A, 7B, and 9A). As another example, if the solenoid coil 1402 is used rather than the RF coil 114, the end 1404 is coupled to the output 416 (FIG. 4). As yet another example, if the solenoid coil 1402 is used rather than the RF coil 904, the end 1404 is coupled to the fourth capacitor 910 (FIG. 9A). As yet another example, if a solenoid coil 1402 is used rather than an RF coil 904, end 1404 is coupled to point 960 (FIG. 9B). As another example, if a solenoid coil 1402 is used rather than an RF coil 904, end 1404 is coupled to filter 983 (FIG. 9C). As yet another example, if a solenoid coil 1402 is used rather than an RF coil 904, end 1404 is coupled to filter 992 (FIG. 9D).

[0263] When the RF signal 1408 is received by the solenoid coil 1402, a magnetic field is generated by the solenoid coil 1402 and spreads through the dielectric window 314 into the plasma chamber 1400. The RF signal 1408 is an example of any of the RF signals 123 (FIG. 1), 426 (FIG. 4), 706 (FIG. 7A), 756 (FIG. 7B), 922 (FIG. 9A), 920 (FIG. 9A), 966 (FIG. 9B), 970 (FIG. 9D), 984 (FIG. 9E), and 994 (FIG. 9F). When one or more process gases are supplied to the plasma chamber 1400 in addition to the RF signal 1408, a plasma is struck or sustained in the plasma chamber 1400 to process the substrate S. When the plasma is formed in the plasma chamber 1400, RF power is reflected from the plasma chamber 1400 in the form of a reflected RF signal 1410 through the solenoid coil 1402 toward the point 1404. The reflected RF signal 1410 is an example of any of the reflected RF signals 115 (FIG. 1), 428 (FIG. 4), 708 (FIG. 7A), 758 (FIG. 7B), 924 (FIG. 9A), 930 (FIG. 9A), 980 (FIG. 9B), 974 (FIG. 9B), 986 (FIG. 9C), and 996 (FIG. 9D).

[0264] In one embodiment, referring to FIG. 9A, a solenoid coil 1402 is used instead of the RF coil 114 and another solenoid coil is used instead of the RF coil 904.

[0265] In one embodiment, referring to FIG. 9B, a solenoid coil 1402 is used in place of the RF coil 114 and another solenoid coil is used in place of the RF coil 904.

[0266] 15 is a diagram of one embodiment of a plasma system 1500 having a substrate support 310 to illustrate the use of the LFMPS 102 and the HFMPS 102. The plasma system 1500 includes an LF source RFG 402, an HF source RFG 404, a dual frequency matcher 406, a plasma chamber 308, an LFMPS 102, an HFMPS 104, a first filter 106, a second filter 108, a first capacitor 110, and a second capacitor 112. In the plasma system 1500, the point 122 is coupled to the lower electrode 311 via an RF connection 125 (e.g., an RF transmission line, etc.).

[0267] A plasma is generated or maintained in the plasma chamber 308 when the modified RF signal 426 is provided to the RF coil 312, the composite RF signal is provided to the lower electrode 311, and one or more process gases are provided to the plasma chamber 308. When the plasma is generated or maintained, RF power is reflected from the plasma through the lower electrode 311 towards the RF connection 125 in the form of a reflected RF signal 115.

[0268] FIG. 16A is a diagram of an embodiment of a system 1600 to illustrate a master-slave configuration. In this master-slave configuration, the LFMPS 102 is the controlling side and the HFMPS 104 is the controlled side. For example, the controller of the LFMPS 102 is coupled to the controller of the HFMPS 104 via a transfer cable 1602. Rather than the host computer 1204 (FIG. 12) providing the RF frequency, one or more parameter levels, and transition times between parameter levels of the RF signal 116B generated by the HFMPS 104 in the recipe signal 1224 (FIG. 12A-1), the controller of the LFMPS 102 generates the recipe signal 1604 and transmits the recipe signal 1604 to the controller of the HFMPS 104 via the transfer cable 1602. The recipe signal 1604 is an example of the recipe signal 1224 (FIG. 12A-2). The recipe signal 1604 includes a radio frequency, one or more parameter levels, and a transition time between the parameter levels, of the RF signal 116B output by the HFMPS 104. The HFMPS 104 generates the RF signal 116B based on the radio frequency, one or more parameter levels, and the transition time between the parameter levels indicated in the recipe signal 1604.

[0269] FIG. 16B is a diagram of an embodiment of a system 1610 to illustrate a master-slave configuration. In this master-slave configuration, the HFMPS 104 is the controlling side and the LFMPS 102 is the controlled side. For example, the controller of the HFMPS 104 is coupled to the controller of the LFMPS 102 via a transfer cable 1612. Rather than the host computer 1204 (FIG. 12) providing the low frequency, one or more parameter levels, and transition times between parameter levels of the RF signal 116A generated by the LFMPS 104 in the recipe signal 1224 (FIG. 12A-1), the controller of the HFMPS 104 generates a recipe signal 1614 and transmits the recipe signal 1614 to the controller of the LFMPS 102 via the transfer cable 1612. The recipe signal 1614 is an example of the recipe signal 1224 (FIG. 12A-2). The recipe signal 1614 includes a low frequency, one or more parameter levels, and a transition time between the parameter levels for the RF signal 116A output by the LFMPS 102. The LFMPS 102 generates the RF signal 116A based on the low frequency, one or more parameter levels, and the transition time between the parameter levels indicated in the recipe signal 1614.

[0270] FIG. 16C is a diagram of an embodiment of a system 1620 to illustrate a master-slave configuration. In this master-slave configuration, the LF source RFG 402 is the controlling side and the HFMPS 104 is the controlled side. For example, the DSP of the LF source RFG 402 is coupled to the controller of the HFMPS 104 via a transfer cable 1622. Rather than the host computer 1204 (FIG. 12) providing the high frequency, one or more parameter levels, and transition times between parameter levels of the RF signal 116B generated by the HFMPS 104 in the recipe signal 1224 (FIG. 12A-1), the DSP of the LF source RFG 402 generates the recipe signal 1624 and transmits the recipe signal 1624 to the controller of the HFMPS 104 via the transfer cable 1622. The recipe signal 1624 is an example of the recipe signal 1224 (FIG. 12B). The recipe signal 1624 includes a radio frequency, one or more parameter levels, and a transition time between the parameter levels, of the RF signal 116B output by the HFMPS 104. The HFMPS 104 generates the RF signal 116B based on the radio frequency, one or more parameter levels, and the transition time between the parameter levels indicated in the recipe signal 1624.

[0271] FIG. 16D is a diagram of one embodiment of a system 1630 to illustrate a master-slave configuration. In this master-slave configuration, the HF source RFG 404 is the controlling side and the LFMPS 102 is the controlled side. For example, the DSP of the HF source RFG 404 is coupled to the controller of the LFMPS 102 via a transfer cable 1632. Rather than the host computer 1204 (FIG. 12) providing the low frequency, one or more parameter levels, and transition times between parameter levels of the RF signal 116A generated by the LFMPS 102 in the recipe signal 1224 (FIG. 12A-1), the DSP of the HF source RFG 404 generates a recipe signal 1634 and transmits the recipe signal 1634 to the controller of the LFMPS 102 via the transfer cable 1632. The recipe signal 1634 is an example of the recipe signal 1224 (FIG. 12A-2). The recipe signal 1634 includes a low frequency, one or more parameter levels, and a transition time between the parameter levels of the RF signal 116A output by the LFMPS 102. The LFMPS 102 generates the RF signal 116A based on the low frequency, one or more parameter levels, and the transition time between the parameter levels indicated in the recipe signal 1634.

[0272] FIG. 16E is a diagram of an embodiment of a system 1640 to illustrate a master-slave configuration. In this master-slave configuration, the LFMPS 102 is the controlling side and the HF source RFG 404 is the controlled side. For example, the controller of the LFMPS 102 is coupled to the DSP of the HF source RFG 404 via a transfer cable 1642. Rather than the host computer 1204 (FIG. 12) providing the high frequency, one or more parameter levels, and transition times between parameter levels of the RF signal 422 generated by the HF source RFG 404 in the recipe signal 1286 (FIG. 12B), the controller of the LFMPS 102 generates a recipe signal 1644 and sends the recipe signal 1644 to the DSP of the HF source RFG 404 via the transfer cable 1642. The recipe signal 1644 is an example of the recipe signal 1286 (FIG. 12B). The recipe signal 1644 includes a radio frequency, one or more parameter levels, and transition times between the parameter levels of the RF signal 422 output by the HF source RFG 404. The HF source RFG 404 generates the RF signal 422 based on the radio frequency, one or more parameter levels, and transition times between the parameter levels indicated in the recipe signal 1644.

[0273] FIG. 16F is a diagram of an embodiment of a system 1650 to illustrate a master-slave configuration. In this master-slave configuration, the HFMP 104 is the controlling side and the LF source RFG 402 is the controlled side. For example, the controller of the HFMPS 104 is coupled to the DSP of the LF source RFG 402 via a transfer cable 1652. Instead of the host computer 1204 (FIG. 12) providing the low frequency, one or more parameter levels, and transition times between parameter levels of the RF signal 420 generated by the LF source RFG 402 in the recipe signal 1286 (FIG. 12B), the controller of the HFMPS 104 generates the recipe signal 1654 and sends the recipe signal 1654 to the DSP of the LF source RFG 402 via the transfer cable 1652. The recipe signal 1654 is an example of the recipe signal 1286 (FIG. 12B). The recipe signal 1654 includes a low frequency, one or more parameter levels, and transition times between the parameter levels of the RF signal 420 output by the LF source RFG 402. The LF source RFG 402 generates the RF signal 420 based on the low frequency, one or more parameter levels, and transition times between the parameter levels indicated in the recipe signal 1654.

[0274] The embodiments described herein may be practiced with a variety of computer system configurations including handheld hardware units, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers, etc. The embodiments may also be practiced in distributed computing environments where tasks are performed by remote processing hardware units that are linked through a network.

[0275] In some embodiments, the controller is part of a system that may be part of the above examples. Such systems include semiconductor processing equipment such as one or more processing tools, one or more chambers, one or more processing platforms, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems are integrated with electronics for the creation of integrated circuits to control the operation of the system before, during, and after processing of a semiconductor wafer or substrate. The electronics are referred to as "controllers" that may control various parts or sub-parts of one or more systems. Depending on the processing requirements and / or type of system, the controller is programmed to control any of the processes disclosed herein, such as delivery of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, RF generator settings, RF matching circuit settings, frequency settings, flow settings, fluid delivery settings, position and operation settings, wafer loading and unloading to and from the tool and other transport tools and / or load locks that are connected or interfaced to the system.

[0276] Broadly speaking, in various embodiments, a controller is defined as electronic equipment having various integrated circuits, logic, memory, and / or software that, for example, receive instructions, issue instructions, control operations, enable cleaning operations, enable end-point measurements, and the like. Integrated circuits include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as ASICs, PLDs, and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). Program instructions are instructions communicated to the controller in the form of various individual settings (or program files) that define parameters, factors, variables, etc., for performing a particular process on or for a semiconductor wafer or for a system. Program instructions, in some embodiments, are part of a recipe defined by a process engineer to accomplish one or more processing steps during the manufacture of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer types.

[0277] The controller, in some embodiments, is part of a computer that is integrated into the system, coupled to the system, or otherwise networked to the system, or a combination thereof. For example, the controller may be all or part of a host computer system in the "cloud" or at a fab that allows remote access of wafer processing. By allowing remote access to the system, the computer may monitor the current progress of an assembly operation, review the history of past assembly operations, review trends or performance criteria from multiple assembly operations, modify parameters of a current process, set up processing steps following a current process, or initiate a new process.

[0278] In some embodiments, a remote computer (e.g., a server) provides the process recipe to the system over a network, including a local network or the Internet. The remote computer includes a user interface that allows for input or programming of parameters and / or settings, which are then communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of data that defines parameters, factors, and / or variables for each processing step performed during one or more operations. It should be understood that the parameters, factors, and / or variables are specific to the type of process being performed and the type of tool the controller is configured to interface with or control. Thus, as described above, the controller is distributed, such as by including one or more separate controllers that are networked together and work toward a common purpose, such as the process and control described herein. An example of a controller distributed for such purposes includes one or more integrated circuits on the chamber that are combined to control the process on the chamber and communicate with one or more integrated circuits located remotely (e.g., at the platform level or as part of the remote computer).

[0279] Without being limited thereto, in various embodiments, exemplary systems to which the present methods may be applied include plasma etch chambers or modules, deposition chambers or modules, spin rinse chambers or modules, metal plating chambers or modules, clean chambers or modules, bevel edge etch chambers or modules, physical vapor deposition (PVD) chambers or modules, chemical vapor deposition (CVD) chambers or modules, atomic layer deposition (ALD) chambers or modules, atomic layer etch (ALE) chambers or modules, ion implantation chambers or modules, track chambers or modules, and any other semiconductor processing systems associated with or used in the fabrication and / or manufacturing of semiconductor wafers.

[0280] It is further noted that in some embodiments, the above operations are applicable to various types of plasma chambers, such as plasma chambers including inductively coupled plasma (ICP) reactors, transformer coupled plasma chambers, capacitively coupled plasma chambers, conductor tools, dielectric tools, plasma chambers including electron cyclotron resonance (ECR) reactors, etc. For example, one or more RF generators are coupled to an inductor in an ICP reactor. Example shapes of the inductor include a solenoid, a dome coil, a flat coil, etc.

[0281] As described above, depending on the process step or steps being performed by the tool, the host computer communicates with one or more of other tool circuits or modules, other tool parts, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, main computers, other controllers, or tools used in material transport to move containers of wafers in and out of tool locations and / or load ports within a semiconductor manufacturing factory.

[0282] In view of the above embodiments, it should be understood that some of the embodiments employ various computer-implemented operations involving data stored in computer systems. These operations physically manipulate physical quantities. Any of the operations described herein that form part of the embodiments are useful machine operations.

[0283] Some embodiments also relate to a hardware unit or apparatus for performing these operations. An apparatus is specially configured for a special purpose computer. When defined as a special purpose computer, the computer performs other processes, program execution, or routines that are not part of the special purpose while remaining operable for the special purpose.

[0284] In some embodiments, the operations may be processed by a computer selectively activated or configured by one or more computer programs stored in a computer memory or cache, or obtained over a computer network. When data is obtained over a computer network, the data may be processed by other computers on the computer network, e.g., a cloud of computing resources.

[0285] Also, in one or more embodiments, it may be made as computer readable code on a non-primary computer readable medium. A non-primary computer readable medium is a data storage hardware unit (such as a memory device) that stores data, which is then read by a computer system. Examples of non-primary computer readable media include hard drives, network attached storage (NAS), ROM, RAM, compact disc-ROM (CD-ROM), recordable CD (CD-R), rewritable CD (CD-RW), magnetic tape, and other optical and non-optical data storage hardware units. In some embodiments, the non-primary computer readable medium includes computer readable tangible media distributed over network-coupled computer systems such that the computer readable code is stored and executed in a distributed manner.

[0286] Although the method operations above have been described in a particular order, it should be understood that in various embodiments, other housekeeping operations are performed between operations, the method operations are coordinated to occur at slightly different times, are distributed in a system that allows the method operations to occur at various intervals, or are performed in an order different from that described above.

[0287] It should be further noted that in some embodiments, one or more features from any of the above-described embodiments may be combined with one or more features of any of the other embodiments also described above without departing from the scope of the various embodiments described in this disclosure.

[0288] Although the foregoing embodiments have been described in some detail for clarity of understanding, it will be apparent that certain changes and modifications can be practiced within the scope of the appended claims. The present embodiments are therefore to be considered as illustrative and not restrictive, and the embodiments are not to be limited to the details given herein.

Claims

1. 1. A system comprising: a first matchless plasma source configured to generate a first sinusoidal waveform generated based on a first rectangular waveform, the first sinusoidal waveform having a first frequency; a first filter coupled to the first matchless plasma source and configured to filter a second frequency so that it does not interfere with the first sinusoidal waveform; a first capacitive circuit coupled to the first filter and configured to output a first radio frequency (RF) signal by balancing a reactance of the first filter and a reactance of an RF coil of a plasma chamber, and configured to provide the first RF signal to a point coupled to the RF coil; a second matchless plasma source configured to generate a second sinusoidal waveform generated based on a second rectangular waveform, the second sinusoidal waveform having the second frequency; a second filter coupled to the second matchless plasma source and configured to filter the first frequency so that it does not interfere with the second sinusoidal waveform; a second capacitive circuit coupled to the second filter and configured to output a second RF signal by balancing a reactance of the second filter and the reactance of the RF coil, and configured to provide the second RF signal to the point; A system comprising:

2. 10. The system of claim 1, The system wherein the first RF signal is combined with the second RF signal at the point to provide a combined RF signal to the RF coil.

3. 10. The system of claim 1, The second frequency is greater than the first frequency.

4. 10. The system of claim 1, The system further comprises the plasma chamber including the RF coil and a substrate support.

5. 5. The system of claim 4, a first bias RF generator configured to generate a third RF signal; a matcher coupled to the first bias RF generator; a second bias RF generator coupled to the matcher and configured to generate a fourth RF signal, the matcher configured to receive the third RF signal and the fourth RF signal, modify impedance of the third RF signal and the fourth RF signal to output a modified RF signal, and provide the modified RF signal to the substrate support; The system further comprises:

6. 5. The system of claim 4, The substrate support is coupled to a ground potential.

7. 10. The system of claim 1, The system, wherein the first capacitive circuit is configured to receive a reflected RF signal having RF power reflected from the plasma chamber, the reflected RF signal having the second frequency.

8. 10. The system of claim 1, The system, wherein the second capacitive circuit is configured to receive a reflected RF signal having RF power reflected from the plasma chamber, the reflected RF signal having the first frequency.

9. 10. The system of claim 1, A system in which there is no match box between the first matchless plasma source and the RF coil, and there is no match box between the second matchless plasma source and the RF coil.

10. 1. A system comprising: a matchless plasma source configured to generate a sinusoidal waveform generated based on a square waveform, the sinusoidal waveform having a first frequency; a first filter coupled to the matchless plasma source and configured to filter a second frequency from interfering in the sinusoidal waveform; a capacitive circuit coupled to the first filter and configured to output a first radio frequency (RF) signal by balancing a reactance of the first filter and a reactance of an RF coil of a plasma chamber, and configured to provide the first RF signal to a point coupled to the RF coil; a source RF generator configured to generate a second RF signal having the second frequency; an impedance matching network coupled to the source RF generator and configured to receive the second RF signal and modify the impedance of the second RF signal to output a modified RF signal, the impedance matching network including a second filter configured to filter the first frequency from interfering with the second RF signal, the impedance matching network configured to provide the modified RF signal to the point; A system comprising:

11. 11. The system of claim 10, The point is configured to combine the first RF signal with the modified RF signal and provide a combined RF signal to the RF coil.

12. 11. The system of claim 10, The system wherein the second frequency is greater than, equal to, or less than the first frequency.

13. 11. The system of claim 10, The system further comprises the plasma chamber including the RF coil and a substrate support.

14. 14. The system of claim 13, a first bias RF generator configured to generate a third RF signal; a matcher coupled to the first bias RF generator; a second bias RF generator coupled to the matcher and configured to generate a fourth RF signal, the matcher configured to receive the third RF signal and the fourth RF signal, modify impedance of the third RF signal and the fourth RF signal to output a modified RF signal, and provide the modified RF signal to the substrate support; The system further comprises:

15. 14. The system of claim 13, The substrate support is coupled to a ground potential.

16. 11. The system of claim 10, The capacitive circuit is configured to receive a reflected RF signal having RF power reflected from the plasma chamber, the reflected RF signal having the second frequency.

17. 11. The system of claim 10, A system in which there is no match box, including a physical housing, between the matchless plasma source and the RF coil.

18. 1. A system comprising: a first matchless plasma source configured to generate a first sinusoidal waveform generated based on a first rectangular waveform, the first sinusoidal waveform having a first frequency; a first filter coupled to the first matchless plasma source and configured to filter a second frequency so that it does not interfere with the first sinusoidal waveform; a first capacitive circuit coupled to the first filter and configured to output a first radio frequency (RF) signal by balancing a reactance of the first filter with a reactance of a first RF coil of a plasma chamber, and configured to provide the first RF signal to a point coupled to the first RF coil; a second matchless plasma source configured to generate a second sinusoidal waveform generated based on a second rectangular waveform, the second sinusoidal waveform having the second frequency; a second filter coupled to the second matchless plasma source and configured to filter the first frequency so that it does not interfere with the second sinusoidal waveform; a second capacitive circuit coupled to the second filter and configured to output a second RF signal by balancing a reactance of the second filter, a reactance of the first RF coil, and a reactance of a second RF coil of the plasma chamber; a signal splitter coupled to the second capacitive circuit and configured to split the second RF signal into a third RF signal and a fourth RF signal, the signal splitter including a third capacitive circuit and a fourth capacitive circuit; the third capacitive circuit is configured to receive the third RF signal and provide a fifth RF signal to the point by balancing the reactance of the first RF coil and the reactance of the second filter in the plasma chamber, and the fourth capacitive circuit is configured to receive the fourth RF signal and provide a sixth RF signal to the second RF coil by balancing the reactance of the second RF coil and the reactance of the second filter.

19. 20. The system of claim 18, The system, wherein the point is configured to combine the first RF signal with the fifth RF signal to provide a seventh RF signal to the first RF coil.

20. 20. The system of claim 18, The second frequency is greater than the first frequency.

21. 20. The system of claim 18, The system further comprises the plasma chamber including the first RF coil, the second RF coil, and a substrate support.

22. 22. The system of claim 21, a first bias RF generator configured to generate a seventh RF signal; a matcher coupled to the first bias RF generator; a second bias RF generator coupled to the matcher and configured to generate an eighth RF signal, the matcher configured to receive the seventh RF signal and the eighth RF signal, modify impedance of the seventh RF signal and the eighth RF signal to output a modified RF signal, and provide the modified RF signal to the substrate support; The system further comprises:

23. 22. The system of claim 21, The substrate support is coupled to a ground potential.

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