System and method for achieving peak ion energy enhancement with small angular divergence

Abstract

To provide a system and method for achieving peak ionic energy enhancement with small angular divergence.SOLUTION: In a plasma tool 100, a plurality of radio frequency (RF) generators RFGx, RFGy connected to an upper electrode 106 associated with a plasma chamber 108 operates in two different states (e.g. two different frequency levels) for pulsing of the RF generators. The pulsing of the RF generators facilitates the transition of ion energy during one of the states to the other of the states, thereby increasing the ion energy during the other state and further increasing the processing speed of the substrate.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] This embodiment relates to a system and method for achieving enhanced peak ion energy with small angular divergence.

Background Art

[0002] In some plasma processing systems, a radio frequency (RF) signal is supplied to an electrode within a plasma chamber. The RF signal is used to generate plasma within the plasma chamber. The plasma is used for various operations, such as cleaning a substrate disposed on a lower electrode, etching the substrate, and the like. During substrate processing using the plasma, the RF signal is continuous.

[0003] The embodiments described in this disclosure have arisen in such a background.

Summary of the Invention

[0004] Embodiments of this disclosure provide a system, apparatus, method, and computer program for achieving enhanced peak ion energy with small low angular divergence. It should be understood that this embodiment can be implemented in various forms, such as a process, apparatus, system, device, or a method recorded on a computer-readable medium. Some embodiments are described below.

[0005] In some embodiments, the systems and methods described herein enhance ion energy without increasing or substantially increasing the supplied radio frequency (RF) bias voltage or RF bias power, creating a narrow angular divergence at the peak energy. The narrow angular divergence at the peak energy is used to achieve high aspect ratio etching.

[0006] The systems and methods described herein utilize high-frequency and low-frequency levels during a pulse period. The high-frequency level is utilized by a high-frequency RF generator (e.g., a 27-megahertz RF generator or a 60-megahertz RF generator), and the low-frequency level is utilized by another low-frequency RF generator (e.g., a 2-megahertz RF generator, a 13.56-megahertz RF generator, or a 400-kilohertz RF generator). The systems and methods have the advantage of facilitating a tight (narrow, etc.) ion angle while increasing the peak ion energy (e.g., an increase of more than 35%) compared to the peak ion energy achieved by de-pulsing the RF signal (e.g., a continuous-wave RF signal). The tight ion angle and increased peak ion energy are achieved as a result of synchronized low-frequency and high-frequency RF voltage pulses. At the start of the high-frequency level, the plasma ions receive a voltage boost from the previous low-frequency level (e.g., the previous low-frequency level). For example, the voltage from the low-frequency level is added to the voltage from the low-frequency level to the high-frequency level following it. As a result, at the same RF bias voltage, the peak energy in the ion energy-angle distribution function (IEADF) of the systems and methods described herein is higher compared to continuous wave techniques. The sheath voltage of the plasma sheath charges and discharges based on the following equation (1).

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[0007] Furthermore, the systems and methods described herein enhance ion energy without substantially increasing the bias voltage or bias power by causing the amount of energy or voltage from the low-power parameter level to contribute to the amount of energy at the high-power parameter level, thereby producing a narrow angular divergence at the peak energy. The systems and methods described herein utilize the high-power parameter level during the high state and the low-power parameter level during the low state. The low-power parameter level is a certain percentage of the power parameter level during the high state. The high-power and low-power parameter levels are supplied by the same RF generator (e.g., a high-frequency RF generator or a low-frequency RF generator). Thus, at the start of the high state, the plasma sheath, acting as a capacitor, retains the previous low voltage or power at the low-power parameter level, which is later added to the high voltage or power at the high-power parameter level, resulting in higher peak energy in the IEADF. The peak energy is higher during both the high and low states at the same bias voltage compared to continuous-wave techniques. The voltage of the plasma sheath charges and discharges based on equation (1).

[0008] At the start of the high-power parameter level, plasma ions move through the plasma sheath and collide with the substrate at a higher voltage than in continuous-wave technology. The voltage or energy from the previous low-power parameter level (e.g., the previous low-power parameter level) contributes to the high-power parameter level. The addition of voltage to the high-power parameter level increases the voltage of the plasma sheath, further increasing the denominator in equation (2). A larger denominator in equation (2) results in a narrower ion angle. Also, unlike continuous-wave technology, because the plasma sheath is initially thin during the transition from the low-power parameter level to the high-power parameter level, plasma ions experience fewer collisions and scattering, maintaining higher energy and a tighter ion angle. Collisions and scattering are less compared to the thicker sheath in continuous-wave mode. Energy-enhanced ions at peak energy during the high-power parameter level maintain a tighter ion angle, which is utilized in high-aspect-ratio etching, compared to continuous-wave mode. Also, during the low-power parameter level, the ion temperature T at the sheath edge...i Because the power is low, the ion angle divergence during the transition from low-power parameter levels to high-power parameter levels is narrower compared to continuous wave (CW) techniques. All of these factors together enhance the peak energy in the IEDF and narrow the ion angle at this peak energy. Furthermore, pulsing between low-power and high-power parameter levels prevents the mask from being severely corroded compared to continuous wave techniques.

[0009] In one embodiment, a method is disclosed for operating a plasma chamber to increase ion energy and reduce angular divergence of ions directed toward the substrate surface during an etching operation. The method comprises receiving a pulsed signal to drive the operation of the plasma chamber. The pulsed signal has two states, including a first state and a second state. The method further comprises operating a primary RF generator at a primary frequency level during the first state and keeping the primary RF generator off during the second state. The operation of the primary RF generator during the first state creates an increased charge in the plasma sheath formed on the substrate. The increased charge increases the thickness of the plasma sheath. The method further comprises operating a secondary RF generator at a secondary frequency level during the second state and keeping the secondary RF generator off during the first state. The operation of the secondary RF generator during the second state utilizes at least a portion of the increased charge in the plasma sheath generated during the first state as additional power to enhance the ion energy generated during the second state. The additional power reduces angular divergence of ions when directed toward the substrate surface. The primary and secondary RF generators are connected to the upper electrodes associated with the plasma chamber via impedance matching circuits. The method comprises keeping the primary and secondary RF generators operating in the first and second states in accordance with pulse signals to enhance etching operation over multiple cycles of the first and second states.

[0010] In various embodiments, methods are disclosed for operating a plasma chamber to increase ion energy and reduce angular divergence of ions directed toward the substrate surface during etching operations. The method comprises receiving a pulsed signal to drive the operation of the plasma chamber. The method further comprises operating a primary RF generator at a first primary frequency level during a first state and a second primary frequency level during a second state. The operation of the primary RF generator during the first state generates an increased charge in the plasma sheath formed on the substrate. The method further comprises operating a secondary RF generator at a first secondary frequency level during a first state and a second secondary frequency level during a second state. The operation of the secondary RF generator during the second state utilizes at least a portion of the increased charge in the plasma sheath generated during the first state as additional power to enhance the ion energy generated during the second state. Each of the first primary frequency level, second primary frequency level, first secondary frequency level, and second secondary frequency level is not zero. For example, neither the primary nor the secondary RF generator is off during the first and second states. The method comprises keeping primary and secondary RF generators operating in the first and second states in accordance with pulse signals to enhance the etching operation over multiple cycles of the first and second states.

[0011] In some embodiments, systems are disclosed for operating a plasma chamber to increase ion energy and reduce angular divergence of ions directed toward the substrate surface during etching operations. The system comprises a primary RF generator having a primary power supply that generates a primary RF signal. The system further comprises a secondary RF generator having a secondary power supply that generates a secondary RF signal. The system further comprises an impedance matching network connected to the primary and secondary power supplies. The impedance matching network receives the primary and secondary RF signals and generates a modulated RF signal. The system comprises a plasma chamber having an upper electrode connected to the impedance matching network. The plasma chamber receives the modulated RF signal. The primary RF generator comprises one or more processors. One or more processors of the primary RF generator receive pulse signals and drive the operation of the plasma chamber. One or more processors operate the primary RF generator at a primary frequency level during a first state and keep the primary RF generator off during a second state. The operation of the primary RF generator during the first state creates an increased charge in the plasma sheath formed on the substrate. The increased charge increases the thickness of the plasma sheath. The secondary RF generator comprises one or more processors configured to receive pulse signals. The one or more processors of the secondary RF generator operate the secondary RF generator at a secondary frequency level during the second state and keep it off during the first state. The operation of the secondary RF generator during the second state utilizes at least a portion of the increased charge of the plasma sheath generated during the first state as additional power to enhance the ion energy generated during the second state. This additional power reduces the angular divergence of ions when directed toward the substrate surface. The primary and secondary RF generators continue to operate in the first and second states according to the pulse signals to enhance the etching operation over multiple cycles of the first and second states.

[0012] Another embodiment will become apparent from the following detailed description, which will be based on the attached drawings. [Brief explanation of the drawing]

[0013] The embodiments can be best understood by referring to the following description made in connection with the accompanying drawings.

[0014] [Figure 1A] A block diagram showing one embodiment of a plasma tool to explain two-state pulsing of a frequency level to achieve enhanced peak ion energy with low angular divergence.

[0015] [Figure 1B] A diagram showing an embodiment of a graph to explain two-state pulsing of a frequency level where one state is an off state.

[0016] [Figure 1C] A diagram showing an embodiment of a graph to explain two-state pulsing of a frequency level where both states are non-zero states.

[0017] [Figure 2A] A block diagram showing one embodiment of a plasma tool to explain three-state pulsing of a frequency level to achieve enhanced peak ion energy with low angular divergence.

[0018] [Figure 2B] A diagram showing an embodiment of a graph to explain three-state pulsing of a frequency level.

[0019] [Figure 2C] A diagram showing an embodiment of a graph to explain three-state pulsing of a frequency level.

[0020] [Figure 2D] A diagram showing an embodiment of a graph to explain three-state pulsing of a frequency level.

[0021] [Figure 3]This figure shows multiple graphical embodiments to illustrate how pulsing the frequency level of an RF signal generated by a frequency-pulsing RF generator increases the peak energy of plasma ions incident on the substrate surface.

[0022] [Figure 4] A figure illustrating one embodiment of the graph illustrates how the angular distribution of plasma ions decreases as the bias voltage supplied by the bias RF generator increases.

[0023] [Figure 5] A figure illustrating one embodiment of the graph illustrates that an angular divergence equivalent to that achieved by increasing the bias voltage can be achieved by pulsing the frequency level of the RF generator.

[0024] [Figure 6] A diagram illustrating an embodiment of the graph to explain the difference in the critical dimension (CD) of channels formed within the substrate.

[0025] [Figure 7A] A block diagram illustrating one embodiment of a plasma tool to illustrate the pulsation of power parameter levels to achieve peak ion energy enhancement with low angular divergence.

[0026] [Figure 7B] Figure 7A shows a graph illustrating an embodiment of the pulsed power parameters of the RF signal generated by the RF generator of the plasma tool.

[0027] [Figure 8] A figure showing multiple graph embodiments to illustrate how the vertical directionality of plasma ions increases with increasing bias voltage.

[0028] [Figure 9]A figure illustrating multiple graphical embodiments to illustrate how pulsing the power parameter level of the RF signal generated by the RF generator increases the peak energy of plasma ions incident on the substrate surface.

[0029] [Figure 10] Figure 4 shows one embodiment of the graph.

[0030] [Figure 11] A figure illustrating one embodiment of the graph illustrates that an angular divergence equivalent to that achieved by increasing the bias voltage can be achieved by pulsing the power parameter levels of the RF generator.

[0031] [Figure 12] A figure illustrating a graphical embodiment illustrates the difference in critical dimensions achieved between pulsing power parameter levels and applying continuous wave modes.

[0032] [Figure 13A] A block diagram illustrating one embodiment of a plasma tool to illustrate the pulsation of the power parameter levels of a bias RF generator to achieve peak ion energy enhancement with low angular divergence.

[0033] [Figure 13B] Figure 13A shows a graph illustrating an embodiment of the pulsed power parameter of the RF signal generated by the bias RF generator. [Modes for carrying out the invention]

[0034] The following embodiments describe systems and methods for achieving peak ion energy enhancement with low angular divergence. It is evident that these embodiments can be implemented without some or all of these specific details. Furthermore, detailed descriptions of well-known processing operations have been omitted to avoid unnecessarily obscuring these embodiments.

[0035] Figure 1A is a block diagram showing one embodiment of a plasma tool 100 for achieving peak ion energy enhancement with low angular divergence. The plasma tool 100 comprises a radio frequency (RF) generator RFGx, another RF generator RFGy, a host computer 116, an impedance matching network (IMN) 104, a plasma chamber 108, another IMN 112, and a bias RF generator system 114 comprising one or more bias RF generators. The plasma tool 100 further comprises an RF cable system 137 connecting the RF generator system 114 to the IMN 112, and an RF transmission line 139 connecting the IMN 112 to a chuck 110 of the plasma chamber 108. The RF transmission line 139 comprises a metal rod surrounded by an insulator, the insulator further surrounded by a sheath. The metal rod is connected to a cylinder via an RF strap, the cylinder is connected to the chuck 110. Examples of RF generators RFGx include low-frequency RF generators such as 400 kHz RF generators, 2 MHz RF generators, or 13.56 MHz RF generators. Examples of RF generators RFGy include high-frequency RF generators such as 13.56 MHz, 27 MHz, or 60 MHz RF generators. RF generators RFGy operate at higher frequencies than RF generators RFGx. Examples of host computers 116 include desktop computers, laptop computers, smartphones, or tablets.

[0036] The RF cable system 137 comprises one or more RF cables connecting the bias RF generator system 114 to the IMN 112. If multiple RF cables are included in the RF cable system 137, those RF cables are connected to different inputs of the IMN 112. For example, one RF cable connects the output of an RF generator in the bias RF generator system 114 to an input of the IMN 112, and another RF cable connects the output of another RF generator in the bias RF generator system 114 to a different input of the IMN 112.

[0037] The IMN112 includes electrical circuit components (e.g., inductors, capacitors, resistors, or combinations thereof) to match the impedance of a load connected to the output of the IMN112 with the impedance of a source connected to one or more inputs of the IMN112. For example, the IMN112 matches the impedance of the plasma chamber 108 and RF transmission line 139 connected to the output of the IMN112 with the impedance of the bias RF generator system 114 and RF cable system 137 connected to one or more inputs of the IMN112. In one embodiment, one or more of the electrical circuit components of the IMN112 are tuned to facilitate matching the impedance of a load connected to the output of the IMN112 with the impedance of a source connected to one or more inputs of the IMN112. The IMN112 reduces the possibility of RF power being reflected in the direction toward the source (e.g., from the load toward the source).

[0038] The RF generator RFGx comprises a digital signal processor DSPx, a power parameter controller PWRS1x, another power parameter controller PWRS2x, an automatic frequency controller (AFT) AFTS1x, another automatic frequency controller AFTS2x, an RF power supply Psx, and a driver system 118. An example of an RF power supply used herein includes an RF oscillator. For example, an RF power supply is an electronic circuit that generates a high-frequency oscillating signal (such as a sine wave). Another example of an RF power supply is a crystal oscillator having a crystal resonator that is deformed at a predetermined frequency when a voltage is applied near or to an electrode on the crystal resonator. A processor used herein is an application-specific integrated circuit (ASIC), a programmable logic device (PLD), a central processing unit (CPU), a microprocessor, or a microcontroller. A controller used herein is an application-specific integrated circuit (ASIC), a programmable logic device (PLD), a central processing unit (CPU), a microprocessor, a microcontroller, or a processor. Examples of driver systems used herein include one or more transistors.

[0039] The plasma chamber 108 includes a dielectric window 120, which forms part of the upper wall of the plasma chamber 108. The dielectric window 120 isolates the upper electrode 106 from the internal space of the plasma chamber 108. The dielectric window 120 controls (e.g., reduces) the effect of the electric field induced by the upper electrode 106 within the space of the plasma chamber 108. An example of the upper electrode 106 includes a transformer-coupled plasma (TCP) coil, which comprises one or more coil turns. For example, each coil turn is in the same horizontal plane. In another example, each coil turn is in a different horizontal plane. The upper electrode 106 is inductively coupled to the internal space of the plasma chamber 108 via the dielectric window 120. Examples of materials used to manufacture the dielectric window 120 include quartz or ceramics. In some embodiments, the plasma chamber 108 further comprises other components (not shown), such as a lower dielectric ring surrounding the chuck 110, a lower electrode extension surrounding the lower dielectric ring, and a lower plasma exclusion zone (PEZ) ring. The upper electrode 106 is positioned opposite the chuck 110, which has the lower electrode. For example, the chuck 110 comprises a ceramic layer attached to the top of the lower electrode and an equipment plate attached to the bottom of the lower electrode. The lower electrode is made of metal (e.g., anodized aluminum, aluminum alloy, etc.). The upper electrode 106 is also made of metal.

[0040] A substrate 122 (e.g., a semiconductor wafer) is supported on the upper surface of a chuck 110. Integrated circuits (e.g., ASICs, PLDs, etc.) are manufactured on the substrate 122, and these integrated circuits are used in various devices, such as mobile phones, tablets, smartphones, computers, laptops, and network devices.

[0041] One or more inlet ports (such as those formed within the side wall of the plasma chamber 108) are connected to a central gas supply unit (not shown). The central gas supply unit receives one or more process gases from a gas supply source (not shown). Examples of one or more process gases include oxygen-containing gases (such as O2). Other examples of one or more process gases include fluorine-containing gases, such as tetrafluoromethane (CF4), sulfur hexafluoride (SF6), and hexafluoroethane (C2F6).

[0042] The DSPx is connected to the power parameter controllers PWRS1x and PWRS2x, and the automatic frequency adjusters AFTS1x and AFTS2x. Furthermore, the power parameter controllers PWRS1x and PWRS2x, as well as the automatic frequency adjusters AFTS1x and AFTS2x, are connected to the driver system 118. The driver system 118 is connected to the RF power supply Psx. The RF power supply Psx is connected to the RF cable 124, which is connected to the input of the IMN 104 via the output of the RF generator RFGx.

[0043] The output of IMN104 is connected to end E1 of the upper electrode 106 via RF transmission cable 126. The upper electrode 106 is connected to ground potential at its opposite end (end E2, etc.). An example of RF transmission cable 126 is an RF cable.

[0044] The RF generator RFGy comprises a DSPy, a power parameter controller PWRS1y, another power parameter controller PWRS2y, an automatic frequency adjuster AFTS1y, and another automatic frequency adjuster AFTS2y. The RF generator RFGy further comprises an RF power supply Psy and a driver system 128. The DSPy is connected to the power parameter controllers PWRS1y and PWRS2y, and the automatic frequency adjusters AFTS1y and AFTS2y. Furthermore, the power parameter controllers PWRS1y and PWRS2y, as well as the automatic frequency adjusters AFTS1y and AFTS2y, are connected to the driver system 128. The driver system 128 is connected to the RF power supply Psy. The RF power supply Psy is connected to an RF cable 130, which is connected to an input of the IMN 104, via the output of the RF generator RFGy. The other inputs of the IMN 104 to which the RF cable 130 is connected are different from the input to which the RF cable 124 is connected.

[0045] The IMN104 includes electrical circuit components (e.g., inductors, capacitors, resistors, or combinations of two or more thereof) to match the impedance of a load connected to the output of the IMN104 with the impedance of a source connected to the input of the IMN104. For example, the IMN104 matches the impedance of the plasma chamber 108 and RF transmission cable 126 connected to the output of the IMN104 with the impedance of RF generator RFGx, RF cable 124, RF generator RFGy, and RF cable 130. In one embodiment, one or more of the electrical circuit components of the IMN104 are tuned to facilitate matching the impedance of a load connected to the output of the IMN104 with the impedance of a source connected to the input of the IMN104. The IMN104 reduces the possibility of RF power being reflected in the direction toward the source (e.g., from the load toward the source).

[0046] The host computer 116 comprises a processor 132 and a memory device 134. The processor 132 is connected to the memory device 134. Examples of memory devices include random access memory (RAM) and read-only memory (ROM). For example, a memory device may be flash memory, a hard disk, or a storage device. A memory device is an example of a computer-readable medium. The processor 132 is connected to the DSPx via cable 136 and to the DSPy via cable 138. Examples of cables 136 or 138 include cables used for serial data transfer, cables used for parallel data transfer, and cables used for data transfer by applying the Universal Serial Bus (USB) protocol.

[0047] The control circuit of processor 132 is used to generate pulse signals 102 (e.g., transistor-to-transistor logic (TTL) signals, digital pulse signals, clock signals, signals with a duty cycle, etc.). An example of the control circuit of processor 132 used to generate pulse signals 102 includes a TTL circuit.

[0048] The pulse signal 102 comprises multiple states S1 and S2. For example, state S1 of the pulse signal 102 has a logic level of "1" during part of the pulse signal 102 cycle and a logic level of "0" during another part of the cycle. In various embodiments, states S1 and S2 are executed once during the pulse signal 102 cycle and are repeated over multiple cycles of the pulse signal 102. For example, one cycle of the pulse signal 102 comprises states S1 and S2, and another cycle of the pulse signal 102 comprises states S1 and S2. To illustrate, state S1 is executed during part of the duration of the pulse signal 102 cycle, and state S2 is executed for the remainder of the cycle. As another example, the duty cycle for state S1 is the same as the duty cycle for state S2. To illustrate, each state S1 and S2 of the pulse signal 102 has a 50% duty cycle. As yet another example, the duty cycle for state S1 is different from the duty cycle for state S2. To explain, state S1 of pulse signal 102 has a duty cycle of a%, and state S2 of pulse signal 102 has a duty cycle of (100-a)%, where a is an integer greater than zero. An example of a% is in the range of 10% to 50%. Another example of a% is in the range of 20% to 40%. Yet another example of a% is 25%.

[0049] In various embodiments, instead of the control circuit of processor 132, a clock source (e.g., a crystal oscillator) is used to generate an analog clock signal, which is then converted into a digital signal similar to the pulse signal 102 by an analog-to-digital converter. For example, a crystal oscillator is configured to oscillate in an electric field by applying a voltage to electrodes near the crystal oscillator. In various embodiments, instead of processor 132, a digital clock source generates the pulse signal 102.

[0050] The processor 132 accesses recipes from the memory device 134. Examples of recipes include power parameter setpoints applied to RF generator RFGx during state S1, power parameter setpoints applied to RF generator RFGx during state S2, frequency setpoints applied to RF generator RFGx during state S1, frequency setpoints applied to RF generator RFGx during state S2, power parameter setpoints applied to RF generator RFGy during state S1, power parameter setpoints applied to RF generator RFGy during state S2, frequency setpoints applied to RF generator RFGy during state S1, frequency setpoints applied to RF generator RFGy during state S2, the chemistry of one or more processing gases, or a combination thereof. Examples of power parameter setpoints used herein include voltage setpoints and power setpoints.

[0051] The processor 132 transmits a command to the DSPx along with the pulse signal 102 via the cable 136. The command transmitted to the DSPx via the cable 136 includes information about the pulse signal 102, a power parameter setpoint applied to the RF generator RFGx during state S1, a power parameter setpoint applied to the RF generator RFGx during state S2, a frequency setpoint applied to the RF generator RFGx during state S1, and a frequency setpoint applied to the RF generator RFGx during state S2. The information about the pulse signal 102 indicates to the DSPx that the RF signal generated by the RF generator RFGx transitions from state S1 to state S2 at the transition time tst1 of the pulse signal 102, and that the RF signal transitions from state S2 to state S1 at the transition time tst2 of the pulse signal 102. The DSPx determines from the instruction that the power parameter setpoint for state S1 is applied during state S1 of the pulse signal 102, the power parameter setpoint for state S2 is applied during state S2 of the pulse signal 102, the frequency setpoint for state S1 is applied during state S1 of the pulse signal 102, and the frequency setpoint for state S2 is applied during state S2 of the pulse signal 102. Furthermore, the DSPx determines from the instruction and the pulse signal 102 that the RF signal generated by the RF generator RFGx transitions from state S1 to state S2 at the transition time tst1 of the pulse signal 102, and that the RF signal transitions from state S2 to state S1 at the transition time tst2 of the pulse signal 102. The transition times tst1 and tst2 are repeated in each cycle of the pulse signal 102.

[0052] At the cycle transition time tst2 of pulse signal 102, the DSPx transmits the power parameter setpoint for state S1 to the power parameter controller PWRS1x. Similarly, at the cycle transition time tst1 of pulse signal 102, the DSPx transmits the power parameter setpoint for state S2 to the power parameter controller PWRS2x. Furthermore, at the cycle transition time tst2 of pulse signal 102, the DSPx transmits the frequency setpoint for state S1 to the automatic frequency regulator AFTS1x. Also, at the cycle transition time tst1 of pulse signal 102, the DSPx transmits the frequency setpoint for state S2 to the automatic frequency regulator AFTS2x.

[0053] Upon receiving a power parameter setpoint for state S1, the power parameter controller PWRS1x determines the current amount corresponding to the power parameter setpoint for state S1 (e.g., having a one-to-one relationship, associated, linked, etc.). Based on the current amount generated by the driver system 118 during state S1, the power parameter controller PWRS1x generates a command signal and transmits it to the driver system 118. During state S1, in response to receiving the command signal, the driver system 118 generates a current signal with the current amount and transmits it to the RF power supply Psx. After receiving the current signal, the RF power supply Psx generates an RF signal with the power parameter setpoint for state S1 and supplies that RF signal to the output of the RF generator RFGx and to the input of the IMN104 via the RF cable 124. The power parameter setpoint for state S1 is maintained by the RF power supply Psx of the RF generator RFGx during state S1.

[0054] Similarly, upon receiving a power parameter setpoint for state S2, the power parameter controller PWRS2x determines the amount of current corresponding to the power parameter setpoint for state S2. Based on the amount of current generated by the driver system 118 during state S2, the power parameter controller PWRS2x generates a command signal and transmits it to the driver system 118. During state S2, in response to receiving the command signal, the driver system 118 generates a current signal with the amount of current and transmits it to the RF power supply Psx. After receiving the current signal, the RF power supply Psx generates an RF signal with the power parameter setpoint for state S2 and supplies that RF signal to the output of the RF generator RFGx and the input of the IMN 104 via the RF cable 124. The power parameter setpoint for state S2 is maintained by the RF power supply Psx of the RF generator RFGx during state S2.

[0055] Furthermore, upon receiving a frequency setpoint for state S1, the automatic frequency regulator AFTS1x determines the amount of current corresponding to the frequency setpoint for state S1. Based on the amount of current generated by the driver system 118 during state S1, the automatic frequency regulator AFTS1x generates a command signal and transmits it to the driver system 118. During state S1, in response to receiving the command signal, the driver system 118 generates a current signal with the amount of current and transmits it to the RF power supply Psx. After receiving the current signal, the RF power supply Psx generates an RF signal with a frequency setpoint for state S1 and supplies this RF signal to the output of the RF generator RFGx and the input of the IMN104 via the RF cable 124. The frequency setpoint for state S1 is maintained by the RF power supply Psx during state S1. The RF signal with the power parameter setpoint and the frequency setpoint for state S1 is the RF signal generated by the RF generator RFGx during state S1.

[0056] Similarly, upon receiving a frequency setpoint for state S2, the automatic frequency regulator AFTS2x determines the amount of current corresponding to the frequency setpoint for state S2. Based on the amount of current generated by the driver system 118 during state S2, the automatic frequency regulator AFTS2x generates a command signal and transmits it to the driver system 118. During state S2, in response to receiving the command signal, the driver system 118 generates a current signal with the amount of current and transmits it to the RF power supply Psx. After receiving the current signal, the RF power supply Psx generates an RF signal with a frequency setpoint for state S2 and supplies this RF signal to the output of the RF generator RFGx and to the input of the IMN 104 via the RF cable 124. The frequency setpoint for state S2 is maintained by the RF power supply Psx during state S2. The RF signal with the power parameter setpoint and the frequency setpoint for state S2 is the RF signal generated by the RF generator RFGx during state S2.

[0057] The processor 132 sends a command to the DSPy along with the pulse signal 102 via the cable 138. The command sent to the DSPy via the cable 138 includes information about the pulse signal 102, a power parameter setpoint applied to the RF generator RFGy during state S1, a power parameter setpoint applied to the RF generator RFGy during state S2, a frequency setpoint applied to the RF generator RFGy during state S1, and a frequency setpoint applied to the RF generator RFGy during state S2. The information about the pulse signal 102 indicates to the DSPy that the RF signal generated by the RF generator RFGy transitions from state S1 to state S2 at the transition time tst1 of the pulse signal 102 cycle, and that the RF signal transitions from state S2 to state S1 at the transition time tst2 of the pulse signal 102 cycle. DSPx parses the instruction and determines from the instruction that the power parameter setpoint for state S1 is applied during state S1 of the pulse signal 102, the power parameter setpoint for state S2 is applied during state S2 of the pulse signal 102, the frequency setpoint for state S1 is applied during state S1 of the pulse signal 102, and the frequency setpoint for state S2 is applied during state S2 of the pulse signal 102. Furthermore, DSPy determines from the instruction that the RF signal generated by the RF generator RFGy transitions from state S1 to state S2 at the cycle transition time tst1 of the pulse signal 102, and that the RF signal transitions from state S2 to state S1 at the cycle transition time tst2 of the pulse signal 102.

[0058] At the cycle transition time tst2 of pulse signal 102, DSPy transmits the power parameter setpoint for state S1 to the power parameter controller PWRS1y. Similarly, at the cycle transition time tst1 of pulse signal 102, DSPy transmits the power parameter setpoint for state S2 to the power parameter controller PWRS2y. Furthermore, at the cycle transition time tst2 of pulse signal 102, DSPy transmits the frequency setpoint for state S1 to the automatic frequency regulator AFTS1y. Also, at the cycle transition time tst1 of pulse signal 102, DSPy transmits the frequency setpoint for state S2 to the automatic frequency regulator AFTS2y.

[0059] Upon receiving a power parameter setpoint for state S1, the power parameter controller PWRS1y determines the amount of current corresponding to the power parameter setpoint for state S1. Based on the amount of current generated by the driver system 128 during state S1, the power parameter controller PWRS1y generates a command signal and transmits it to the driver system 128. During state S1, in response to receiving the command signal, the driver system 128 generates a current signal with the amount of current and transmits it to the RF power supply Psy. After receiving the current signal, the RF power supply Psy generates an RF signal with the power parameter setpoint for state S1 and supplies this RF signal to the output of the RF generator RFGy and to other inputs of the IMN104 via the RF cable 130. The power parameter setpoint for state S1 is maintained by the RF power supply Psy during state S1.

[0060] Similarly, upon receiving a power parameter setpoint for state S2, the power parameter controller PWRS2y determines the amount of current corresponding to the power parameter setpoint for state S2. Based on the amount of current generated by the driver system 128 during state S2, the power parameter controller PWRS2y generates a command signal and transmits it to the driver system 128. During state S2, in response to receiving the command signal, the driver system 128 generates a current signal with the amount of current and transmits it to the RF power supply Psy. After receiving the current signal, the RF power supply Psy generates an RF signal with the power parameter setpoint for state S2 and supplies that RF signal to the output of the RF generator RFGy and to other inputs of the IMN 104 via the RF cable 130. The power parameter setpoint for state S2 is maintained by the RF power supply Psy during state S2.

[0061] Furthermore, upon receiving a frequency setpoint for state S1, the automatic frequency regulator AFTS1y determines the amount of current corresponding to the frequency setpoint for state S1. Based on the amount of current generated by the driver system 128 during state S1, the automatic frequency regulator AFTS1y generates a command signal and transmits it to the driver system 128. During state S1, in response to receiving the command signal, the driver system 128 generates a current signal with the amount of current and transmits it to the RF power supply Psy. After receiving the current signal, the RF power supply Psy generates an RF signal with a frequency setpoint for state S1 and supplies this RF signal to the output of the RF generator RFGy and to other inputs of the IMN104 via the RF cable 130. The frequency setpoint for state S1 is maintained by the RF power supply Psy during state S1. The RF signal with the power parameter setpoint and the frequency setpoint for state S1 is the RF signal generated by the RF generator RFGy during state S1.

[0062] Similarly, upon receiving a frequency setpoint for state S2, the automatic frequency regulator AFTS2y determines the amount of current corresponding to the frequency setpoint for state S2. Based on the amount of current generated by the driver system 128 during state S2, the automatic frequency regulator AFTS2y generates a command signal and transmits it to the driver system 128. During state S2, in response to receiving the command signal, the driver system 128 generates a current signal with the amount of current and transmits it to the RF power supply Psy. After receiving the current signal, the RF power supply Psy generates an RF signal with a frequency setpoint for state S2 and supplies this RF signal to the output of the RF generator RFGy and to other inputs of the IMN 104 via the RF cable 130. The frequency setpoint for state S2 is maintained by the RF power supply Psy during state S2. The RF signal with the power parameter setpoint and the frequency setpoint for state S2 is the RF signal generated by the RF generator RFGy during state S2.

[0063] The input to IMN104 receives an RF signal generated by RF power supply Psx from the output of RF generator RFGx via RF cable 124, and the other input receives an RF signal generated by RF power supply Psy from the output of RF generator RFGy via RF cable 130. The impedance of the load connected to the output of IMN104 is matched with the impedance of the source connected to the input of IMN104 to generate a modulated RF signal at the output of IMN104. The modulated RF signal is transmitted to the upper electrode 106 (to the end E1 of the TCP coil, etc.) via RF transmission cable 126.

[0064] Furthermore, the RF generator system 114 generates one or more RF signals. For example, one RF generator in the RF generator system 114 generates an RF signal. Another example is when one RF generator in the RF generator system 114 generates an RF signal, and another RF generator in the RF generator system 114 generates another RF signal. Note that the amount of bias voltage or bias power of the one or more RF signals supplied by the RF generator system 114 is within a predetermined range during multiple states (states S1 and S2, or states S1, S2, and state S3, etc.). To illustrate, the processor 132 transmits the level of bias voltage or bias power to the RF generator system 114 via the cable 117 connecting the RF generator system 114 to the processor 132. The RF generator system 114 generates one or more RF signals having that level of bias voltage or bias power during multiple states. One or more RF signals are generated by the RF generator system 114, similar to the methods described herein for generating RF signals generated by RF generators RFGx or RFGy. The bias voltage or bias power of one or more RF signals is constant (e.g., the same as, or within a predetermined range from, the level of bias voltage or bias power received from processor 132). The bias RF generator system 114 operates in continuous wave mode during states S1 and S2 or between states S1 and S3.

[0065] When one or more RF signals are received by the IMN 112 via the RF cable system 137, an output RF signal is generated by matching the impedance of the load connected to the output of the IMN 112 with the impedance of the sources connected to one or more inputs of the IMN 112. The output RF signal is transmitted to the chuck 110 via the RF transmission line 139.

[0066] When one or more processing gases are supplied between the upper electrode 106 and the chuck 110, a modulated RF signal is supplied to the upper electrode 106, an output RF signal is supplied to the chuck 110, and one or more processing gases are ignited to generate or maintain plasma in the plasma chamber 108. The plasma has a plasma sheath 123 and is used to process the substrate 122 (e.g., etching, material deposition, cleaning, sputtering, etc.). The plasma sheath 123 is the boundary of the plasma formed in the plasma chamber 108. For example, the plasma sheath 123 includes an upper boundary 125A of the plasma formed in the plasma chamber 108 and a lower boundary 125B of the plasma formed in the plasma chamber 108. The upper boundary 125A is closer to the upper electrode 106 than to the chuck 110, and the lower boundary 125B is closer to the chuck 110 than to the upper electrode 106.

[0067] In some embodiments, the terms regulator and controller are interchangeable as used herein.

[0068] In various embodiments, the power parameter controllers PWRS1x and PWRS2x, as well as the automatic frequency regulators AFTS1x and AFTS2x, are modules (e.g., parts thereof) of a computer program executed by the DSPx. Similarly, in some embodiments, the power parameter controllers PWRS1y and PWRS2y, as well as the automatic frequency regulators AFTS1y and AFTS2y, are modules (e.g., parts thereof) of a computer program executed by the DSPy.

[0069] In some embodiments, the power parameter controllers PWRS1x and PWRS2x, as well as the automatic frequency regulators AFTS1x and AFTS2x, are separate integrated circuits connected to the integrated circuit of the DSPx. For example, the power parameter controller PWRS1x is the first integrated circuit of the RF generator RFGx, the power parameter controller PWRS2x is the second integrated circuit of the RF generator RFGx, the automatic frequency regulator AFTS1x is the third integrated circuit of the RF generator RFGx, the automatic frequency regulator AFTS2x is the fourth integrated circuit of the RF generator RFGx, and the DSPx is the fifth integrated circuit of the RF generator RFGx. Each of the first to fourth integrated circuits of the RF generator RFGx is connected to the fifth integrated circuit of the RF generator RFGx.

[0070] Similarly, in various embodiments, the power parameter controllers PWRS1y and PWRS2y, as well as the automatic frequency regulators AFTS1y and AFTS2y, are separate integrated circuits connected to the integrated circuit of the DSPy. For example, the power parameter controller PWRS1y is the first integrated circuit of the RF generator RFGy, the power parameter controller PWRS2y is the second integrated circuit of the RF generator RFGy, the automatic frequency regulator AFTS1y is the third integrated circuit of the RF generator RFGy, the automatic frequency regulator AFTS2y is the fourth integrated circuit of the RF generator RFGy, and the DSPy is the fourth integrated circuit of the RF generator RFGy. 5 It is an integrated circuit. Each of the first to fourth integrated circuits of the RF generator RFGy is connected to the fifth integrated circuit of the RF generator RFGy.

[0071] In various embodiments, an example of RF signal state S1 described herein includes a power parameter setpoint for state S1 and a frequency setpoint for state S1. The power parameter setpoint for state S1 is the operating power parameter setpoint, which is the power parameter level (such as the envelope or amplitude from zero to peak) of the energy or voltage of the RF signal in state S1. The frequency setpoint for state S1 is the operating frequency setpoint, which is the frequency level (such as the envelope or amplitude from zero to peak) of the frequency value of the RF signal in state S1. Similarly, an example of RF signal state S2 described herein includes a power parameter setpoint for state S2 and a frequency setpoint for state S2. The power parameter setpoint for state S2 is the operating power parameter setpoint, which is the power parameter level (such as the envelope or amplitude from zero to peak) of the energy or voltage of the RF signal in state S2. The frequency setpoint for state S2 is the operating frequency setpoint, which is the frequency level (such as the envelope or amplitude from zero to peak) of the frequency value of the RF signal in state S2. Note that in one embodiment, a power parameter level of zero is an example of a power parameter setpoint described herein. Similarly, in one embodiment, a frequency level of zero is an example of a frequency setpoint described herein.

[0072] In various embodiments, three RF generators are connected to the IMN104. For example, an additional RF generator is connected to the IMN104 via another RF cable (not shown) to yet another input of the IMN104. The additional RF generator is added to RF generators RFGx and RF generators RFGy. The yet another input is not the same as the input of the IMN104 to which RF cable 124 is connected, nor is it the same as the other input of the IMN104 to which RF cable 130 is connected. The additional RF generator has the same structure and function as RF generator RFGy, except that the additional RF generator has a different operating frequency (e.g., 2 MHz, 27 MHz, 60 MHz, etc.) than RF generator RFGy. For example, RF generator RFGy has an operating frequency of 13.56 MHz, and the additional RF generator has an operating frequency of 2 MHz, 27 MHz, or 60 MHz. IMN104 combines the RF signals received from RF generator RFGx, RF generator RFGy, and further RF generators, and matches the impedance of the load connected to the output of IMN104 with the impedance of the source (e.g., RF generator RFGx, RF generator RFGy, further RF generators, RF cable 124, RF cable 130, and other RF cables) to generate a modulated RF signal at the output of IMN104.

[0073] In one embodiment, the terms impedance matching circuit and impedance matching network are interchangeable herein.

[0074] In some embodiments, the chuck 110 is connected to ground potential instead of being connected to the IMN 112 and bias RF generator system 114.

[0075] In various embodiments, instead of using a TCP coil as the upper electrode 106, a CCP plate is used as the upper electrode 106. For example, the CCP plate is a circular plate having a circular volume and is located in the horizontal plane within the plasma chamber 108. The CCP plate is formed of a metal such as aluminum or an aluminum alloy. In these embodiments, the plasma chamber 108 does not have a dielectric window 120, but instead has an upper wall. The plasma chamber 108 further includes other components such as an upper dielectric ring surrounding the CCP plate, an upper electrode extension surrounding the upper dielectric ring, and an upper PEZ ring. The CCP plate is positioned opposite the chuck 110.

[0076] In some embodiments, instead of the pulse signal 102 being transmitted from processor 132 to RF generators RFGx and RFGy, the pulse signal 102 is transmitted from a master RF generator to a slave RF generator (such as RF generator RFGy). An example of a master RF generator is RF generator RFGx. To illustrate, the digital signal processor DSPx of RF generator RFGx receives the pulse signal 102 from processor 132 and transmits the pulse signal 102 to the digital signal processor DSPy of RF generator RFGy via a cable (such as a parallel transfer cable, serial transfer cable, or USB cable). Figure 1B shows embodiments of graphs 140, 142, and 144. Graph 140 plots the logic level of the pulse signal 102 against time t. Examples of logic levels include level "0" and level "1". Level "0" is an example of a low logic level, and level "1" is an example of a high logic level. Furthermore, Graph 142 plots the power parameter levels (voltage level or power level, etc.) of the RF signals (e.g., RF signal 146A) generated and supplied by RF generator RFGx against time t. Graph 142 further plots the power parameter levels of the RF signals (e.g., RF signal 146B) generated and supplied by RF generator RFGy against time t. Also, Graph 144 plots the power parameter levels of RF signal 146A against time t. Graph 144 further plots the power parameter levels of the RF signals (e.g., RF signal 146C) generated and supplied by RF generator RFGy against time t.

[0077] Referring to graphs 140 and 142, during each cycle of the pulse signal 102, the pulse signal 102 transitions from state S1 to state S2 at transition time tst1, and transition time tst 2The system then transitions from state S2 to state S1. Furthermore, in state S1, RF signal 146A has a power parameter level "Px1", and RF signal 146B has a power parameter level "0". Also, in state S1, RF signal 146A has a frequency level "fx1", and RF signal 146B has a frequency level "0".

[0078] Furthermore, at transition time tst1, each RF signal 146A and 146B transitions from state S1 to state S2. In state S2, RF signal 146A has a power parameter level of "0", and RF signal 146B has a power parameter level of "Py2". Also in state S2, RF signal 146A has a frequency level of "0", and RF signal 146B has a frequency level of "fy2". Any RF generator described herein is turned off (e.g., becomes inactive, is switched off, etc.) when operating at a frequency level of "0" and a power parameter level of "0". The power parameter level "Py2" is the same as the power parameter level "Px1". Furthermore, the frequency level "fy2" is greater than the frequency level "fx1". At transition time tst2, each RF signal 146A and 146B transitions back from state S2 to state S1.

[0079] Furthermore, note that the duty cycle of state S1 of pulse signal 102 or RF signal 146A or RF signal 146B is the same as the duty cycle of state S2 of pulse signal 102 or RF signal 146A or RF signal 146B. For example, the duty cycle of state S1 is 50%, and the duty cycle of state S2 is 50%. State S1 of RF signal 146A or RF signal 146B accounts for 50% of the pulse signal 102 cycle, and state S2 of RF signal 146A or RF signal 146B accounts for the remaining 50% of the pulse signal 102 cycle.

[0080] In various embodiments, the duty cycle of state S1 of a signal, such as pulse signal 102 or RF signal 146A or RF signal 146B, is different from the duty cycle of state S2 of that signal. For example, the duty cycle of state S1 is 25%, and the duty cycle of state S2 is 75%. State S1 of RF signal 146A or RF signal 146B accounts for 25% of the cycle of pulse signal 102, and state S2 of RF signal 146A or RF signal 146B accounts for the remaining 75% of the cycle of pulse signal 102. As another example, the duty cycle of state S1 is a%, and the duty cycle of state S2 is (100-a)%. State S1 of RF signal 146A or RF signal 146B accounts for a% of the cycle of pulse signal 102, and state S2 of RF signal 146A or RF signal 146B accounts for the remaining (100-a)% of the cycle of pulse signal 102. In explanation, during the calibration operation, the frequency level for state S1, the frequency level for state S2, the power parameter level for state S1, and the power parameter level for state S2, one or more types of processing gases, and the type of material of the substrate 122 are determined based on the etching rate to be achieved, and the rate of cycles of the pulse signal 102 generated by the RF generator RFGx. The etching rate is measured by an etching rate measuring device (ERMD) during the calibration operation. 2 Examples of material types include oxide or metal layers of the substrate 122. Furthermore, the cycle rate of the pulsed signal 102 (during which the RF signal is generated by the RF generator RFGx) is related to the amount of threshold charge accumulated in the plasma sheath 123 during state S1. The relationship between the threshold charge amount, the etching rate, and the cycle rate of the pulsed signal 102 (during which the RF signal is generated by the RF generator RFGx) is stored in the memory device 134. During processing of the substrate 122, the cycle rate of the pulsed signal 102 (during which the RF signal is generated by the RF generator RFGx) is used as part of the recipe or as the duty cycle of the pulsed signal 102.

[0081] The ERMD is connected to the processor 132 via a cable and has a line of sight through a window in the plasma chamber 108. The line of sight is oriented in the space where the plasma is generated within the plasma chamber 108. For example, the ERMD includes a spectrophotometer that monitors the plasma within the plasma chamber 108 to measure the radiation intensity emitted by the plasma through the window. In some embodiments, the window is formed of a transparent material (e.g., glass) that allows light emitted by the plasma to pass through. In various embodiments, the window is a translucent window. The intensity is directly proportional to the etching rate of the layers of the dummy wafer being etched by the plasma. As another example, for a known recipe, from the intensity of the radiation emitted by the plasma during a calibration operation, the ERMD measures the thickness of the dummy wafer at time tm1 and at time tm2 after time tm1 and after the etching of the dummy wafer. The ERMD determines the etching rate of the dummy wafer as the ratio of the difference between the thickness at time tm2 and the thickness at time tm1 to the difference between time tm2 and tm1. In various embodiments, the dummy wafer has the same material as the substrate 122.

[0082] In some embodiments, the power parameter level "Py2" of the RF signal 146B is different (lower or higher) from the power parameter level "Px1" of the RF signal 146A.

[0083] Graph 144 is similar to Graph 142, except that RF signals 146B and 146C have different power parameter levels. For example, RF signal 146B has a power parameter level "Py2" in state S2, and the power parameter level "Py2" of RF signal 146B is greater than the power parameter level "Py2" of RF signal 146C.

[0084] Referring to graphs 140 and 144, state S1 of RF signal 146C is the same as state S1 of RF signal 146B. For example, in state S1, RF signal 146C has a power parameter level of "0". Also, in state S1, RF signal 146C has a frequency level of "0".

[0085] Furthermore, at transition time tst1, RF signal 146C transitions from state S1 to state S2. In state S2, RF signal 146C has a power parameter level "Py2". Also, in state S2, RF signal 146C has a frequency level "fy2". The power parameter level "Py2" of RF signal 146C is lower than the power parameter level "Px1" of RF signal 146A, and the frequency level "fy2" of RF signal 146C is the same as the frequency level of RF signal 146B. At transition time tst2, RF signal 146C transitions back from state S2 to state S1.

[0086] Note that the duty cycle of RF signal 146C in state S1 is the same as the duty cycle of RF signal 146C in state S2. For example, the duty cycle of RF signal 146C in state S1 is 50%, and the duty cycle of RF signal 146C in state S2 is 50%. RF signal 146C in state S1 accounts for 50% of the cycle of pulse signal 102, and RF signal 146C in state S2 accounts for the remaining 50% of the cycle of pulse signal 102.

[0087] In various embodiments, the duty cycle of RF signal 146C in state S1 is different from the duty cycle of RF signal 146C in state S2. For example, the duty cycle of RF signal 146C in state S1 is 25%, and the duty cycle of RF signal 146C in state S2 is 75%. RF signal 146C in state S1 accounts for 25% of the cycles of pulse signal 102, and RF signal 146C in state S2 accounts for the remaining 75% of the cycles of pulse signal 102. As another example, the duty cycle of RF signal 146C in state S1 is a%, and the duty cycle of RF signal 146C in state S2 is (100-a)%. RF signal 146C in state S1 accounts for a% of the cycles of pulse signal 102, and RF signal 146C in state S2 accounts for the remaining (100-a)% of the cycles of pulse signal 102.

[0088] In some embodiments, the power parameter level "Py2" of the RF signal 146C is greater than the power parameter level "Px1" of the RF signal 146A.

[0089] Note that the power parameter levels "Px1" and "Py2" are not zero, as shown in Graph 142. Furthermore, the frequency levels "fx1" and "fy2" are not zero, as shown in Graph 142. Also, the power parameter levels "Px1" and "Py2" are not zero, as shown in Graph 144. Furthermore, the frequency levels "fx1" and "fy2" are not zero, as shown in Graph 144.

[0090] Furthermore, note that the RF generator RFGx is controlled to operate at frequency level "fx1" during state S1. Within the plasma chamber 108, the power parameter of the RF signal generated by RF generator RFGx during state S1 is added to the power parameter of the RF signal generated by RF generator RFGy during state S2. The plasma sheath 123 within the plasma chamber 108 functions as a capacitor. The capacitor charges during state S1 from power parameter level "Px1" associated with frequency level "fx1" and discharges during state S2. Power parameter level "Px1" charges the plasma sheath 123, increasing the amount of charge on the plasma sheath 123 during state S1. Furthermore, the charging of the plasma sheath 123 during state S1 increases the thickness of the plasma sheath 123 during state S1. For example, the thickness of the plasma sheath 123 during state S1 increases because a large number of plasma ions generated during state S1 accumulate on the plasma sheath 123 during state S1. When charging occurs, a portion of the power parameter level "Px1" is added to the power parameter level "Py2". Adding a portion of the power parameter level "Px1" to the power parameter level "Py2" and discharging the capacitor during state S2 increases the ionic energy of the plasma ions in the plasma chamber 108 during state S2 and decreases the angular divergence of ionic energy during state S2. For example, the vertical orientation of the plasma in the plasma chamber 108 increases during state S2, along with adding a portion of the power parameter level "Px1" to the power parameter level "Py2". The ionic energy of the plasma formed in the plasma chamber 108 increases as a result of adding a portion of the power parameter level "Px1" to the power parameter level "Py2". The total power parameter level is a portion of the power parameter level "Px1" and the power parameter level "P yThis includes "2" and enhances the ion energy in state S2. At least a portion of the charge of the plasma sheath 123, which stores the enhanced ion energy in state S1, is discharged from the upper boundary 125A to the lower boundary 125B of the plasma sheath 123 in state S2, thereby reducing the angular divergence of plasma ions incident on the upper surface of the substrate 122 and further increasing the etching rate of the substrate 122.

[0091] Furthermore, note that when the RF generator RFGx operates at the frequency setting point of state S1, the reactance of the plasma sheath 123 of the plasma formed in the plasma chamber 108 during state S1 increases. The reactance of the plasma sheath 123 is inversely proportional to the frequency of the RF generator operating to generate or maintain the plasma sheath 123. Since the reactance of the plasma sheath 123 is higher in state S1 compared to state S2, the ion current through the plasma sheath 123 decreases during state S1.

[0092] As the reactance of the plasma sheath 123 increases, the ionic current of plasma ions at the surface of the substrate 122 decreases during state S1. The resistance R associated with the plasma sheath 123 is inversely proportional to the square of the ionic current for the same amount of energy of plasma ions in states S1 and S2. To supply the same amount (e.g., a constant amount) of power in states S1 and S2, the resistance R associated with the plasma sheath 123 increases during state S1 as the ionic current decreases. The increased resistance R in state S1 increases the time constant RC associated with the plasma sheath 123 during state S1, extending the average time constant for states S1 and S2, thereby increasing the peak energy and decreasing the angle (angle divergence, etc.) in the ion energy-angle distribution function (IEADF). Here, C is the capacitance of the plasma sheath 123, and R is the resistance at the output of the plasma sheath 123. In other words, the output of the plasma sheath 123 is the portion of the plasma sheath 123 through which the ionic current flows. As the resistance R in state S1 increases, the average resistance associated with the plasma sheath 123 in states S1 and S2 increases. The average time constant for states S1 and S2 increases with increasing average resistance. As the average time constant increases, the time it takes for the plasma sheath 123 to discharge increases in either or both states S1 and S2. The extension of discharge time increases the peak ion energy of the plasma in the plasma volume between the plasma sheath 123 in states S1 and S2, and decreases the angular divergence of plasma ions in states S1 and S2.

[0093] Furthermore, during state S1, the plasma sheath 123 is charged based on the power parameter level of state S1. For example, during state S1, the plasma sheath 123 functions as a capacitor, accumulating the amount of charge received from the modulated RF signal generated based on the RF signal supplied by the RF generator RFGx. During state S2, the charge generated in the plasma sheath 123 based on the power parameter level of state S1 (or a portion of the power parameter level of state S1) is added to the charge in the plasma sheath 123 based on the power parameter level of state S2 to generate a total charge corresponding to the total power parameter level. The total power parameter level is the sum of a portion of the power parameter level of state S1 and the power parameter level of state S2. The total charge resides in the plasma sheath 123. The total charge discharges during state S2 according to a time constant RC for the plasma sheath 123 to discharge, which functions as a capacitor. For example, it takes time for the plasma sheath 123 to discharge, but if a continuous-wave mode RF generator is used, the sheath does not need to discharge during plasma operation. As a result of the discharge, the ion energy incident on the surface of the substrate 122 increases, which increases the vertical directionality of the plasma ions in the plasma formed in the plasma chamber 108, reduces the angular divergence of the plasma ions, and speeds up the processing speed of the substrate 122 (such as etching speed or sputtering speed).

[0094] In some embodiments, a portion of the power parameter levels in state S1 will be referred to herein as additional power.

[0095] Figure 1C shows embodiments of graphs 140, 152, and 154. Graph 152 plots the power parameter level (voltage level or power level, etc.) of the RF signal (e.g., RF signal 156A) generated and supplied by RF generator RFGx against time t. Furthermore, graph 152 plots the power parameter level of the RF signal (e.g., RF signal 156B) generated and supplied by RF generator RFGy against time t. Also, graph 154 plots the power parameter level of RF signal 156A against time t. Graph 154 further plots the power parameter level of the RF signal (e.g., RF signal 156C) generated and supplied by RF generator RFGy against time t.

[0096] Referring to graphs 140 and 152, in state S1, RF signal 156A has a power parameter level "Px1", and RF signal 156B has a non-zero power parameter level "Py1". Also, in state S1, RF signal 156A has a frequency level "fx1", and RF signal 156B has a non-zero frequency level "fy1".

[0097] Furthermore, at transition time tst1, each RF signal 156A and 156B transitions from state S1 to state S2. In state S2, RF signal 156A has a power parameter level "Px2", and RF signal 156B has a power parameter level "Py2". Also in state S2, RF signal 156A has a frequency level "fx2", and RF signal 156B has a frequency level "fy2". Power parameter levels Px1, Px2, Py1, and Py2 are the same. Furthermore, frequency level "fx2" is higher than frequency level "fx1", and frequency level "fy1" is lower than frequency level "fy2". At transition time tst2, each RF signal 156A and 156B transitions back from state S2 to state S1.

[0098] In some embodiments, the frequency level "fx2" of RF signal 156A is lower than the frequency level "fx1" of RF signal 156A, and the frequency level "fy1" of RF signal 156B is higher than the frequency level "fy2" of RF signal 156B. In some embodiments, the frequency level "fx2" of RF signal 156A is higher than the frequency level "fx1" of RF signal 156A, and the frequency level "fy1" of RF signal 156B is higher than the frequency level "fy2" of RF signal 156B. In various embodiments, the frequency level "fx2" of RF signal 156A is lower than the frequency level "fx1" of RF signal 156A, and the frequency level "fy1" of RF signal 156B is lower than the frequency level "fy2" of RF signal 156B.

[0099] Note that the duty cycle of state S1 for pulse signal 102 or RF signal 156A or RF signal 156B is the same as the duty cycle of state S2 for pulse signal 102 or RF signal 156A or RF signal 156B. For example, the duty cycle of state S1 is 50%, and the duty cycle of state S2 is 50%. State S1 for RF signal 156A or RF signal 156B accounts for 50% of the pulse signal 102 cycle, and state S2 for RF signal 156A or RF signal 156B accounts for the remaining 50% of the pulse signal 102 cycle.

[0100] In various embodiments, the duty cycle of state S1 of a signal, such as pulse signal 102 or RF signal 156A or RF signal 156B, is different from the duty cycle of state S2 of that signal. For example, the duty cycle of state S1 is 25%, and the duty cycle of state S2 is 75%. State S1 of RF signal 156A or RF signal 156B accounts for 25% of the cycle of pulse signal 102, and state S2 of RF signal 156A or RF signal 156B accounts for the remaining 75% of the cycle of pulse signal 102. As another example, the duty cycle of state S1 is a%, and the duty cycle of state S2 is (100-a)%. State S1 of RF signal 156A or RF signal 156B accounts for a% of the cycle of pulse signal 102, and state S2 of RF signal 156A or RF signal 156B accounts for the remaining (100-a)% of the cycle of pulse signal 102.

[0101] Graph 154 is similar to Graph 152, except that RF signals 156A and 156C have different power parameter levels. For example, RF signal 156A has power parameter levels "Px1" and "Px2" in states S1 and S2, and RF signal 156C has power parameter levels "Py1" and "Py2" in states S1 and S2. The power parameter levels "Py1" and "Py2" of RF signal 156C in states S1 and S2 are lower than the power parameter levels "Px1" and "Px2" of RF signal 156A in states S1 and S2. The power parameter level "Px1" of RF signal 156A is the same as the power parameter level "Px2" of RF signal 156A. Similarly, the power parameter level "Py1" of RF signal 156C is the same as the power parameter level "Py2" of RF signal 156C.

[0102] Graph 1 4Referring to 0 and 154, in state S1, RF signal 156C has a power parameter level "Py1" and a frequency level "fy1". Furthermore, at transition time tst1, RF signal 156C transitions from state S1 to state S2. In state S2, RF signal 156C has a power parameter level "Py2". Also, in state S2, RF signal 156C has a frequency level "fy2". The frequency level "fy2" of RF signal 156C is higher than the frequency level "fy1" of RF signal 156C. At transition time tst2, each RF signal 156A and 156C transitions back from state S2 to state S1.

[0103] In some embodiments, the frequency level "fx2" of RF signal 156A is lower than the frequency level "fx1" of RF signal 156A, and the frequency level "fy1" of RF signal 156C is higher than the frequency level "fy2" of RF signal 156C. In some embodiments, the frequency level "fx2" of RF signal 156A is higher than the frequency level "fx1" of RF signal 156A, and the frequency level "fy1" of RF signal 156C is higher than the frequency level "fy2" of RF signal 156C. In various embodiments, the frequency level "fx2" of RF signal 156A is lower than the frequency level "fx1" of RF signal 156A, and the frequency level "fy1" of RF signal 156C is lower than the frequency level "fy2" of RF signal 156C.

[0104] Note that the duty cycle of RF signal 156C in state S1 is the same as the duty cycle of RF signal 156C in state S2. For example, the duty cycle of RF signal 156C in state S1 is 50%, and the duty cycle of RF signal 156C in state S2 is 50%. RF signal 156C in state S1 accounts for 50% of the pulse signal 102 cycle, and RF signal 156C in state S2 accounts for the remaining 50% of the pulse signal 102 cycle.

[0105] In various embodiments, the duty cycle of RF signal 156C in state S1 is different from the duty cycle of RF signal 156C in state S2. For example, the duty cycle of RF signal 156C in state S1 is 25%, and the duty cycle of RF signal 156C in state S2 is 75%. RF signal 156C in state S1 accounts for 25% of the cycles of pulse signal 102, and RF signal 156C in state S2 accounts for the remaining 75% of the cycles of pulse signal 102. As another example, the duty cycle of RF signal 156C in state S1 is a%, and the duty cycle of RF signal 156C in state S2 is (100-a)%. RF signal 156C in state S1 accounts for a% of the cycles of pulse signal 102, and RF signal 156C in state S2 accounts for the remaining (100-a)% of the cycles of pulse signal 102.

[0106] In some embodiments, the power parameter levels "Py1" and "Py2" of the RF signal 156C are greater than the power parameter levels "Px1" and "Px2" of the RF signal 156A.

[0107] In various embodiments, the power parameter level of the RF signal 156C is pulsed between states S1 and S2, in addition to pulsed frequency levels of the RF signal 156C. For example, Py1 of the RF signal 156C in state S1 is different (higher or lower) from the power parameter level "Py2" of the RF signal 156C in state S2.

[0108] In some embodiments, the power parameter level of the RF signal 156A is pulsed between states S1 and S2, in addition to pulsed frequency levels of the RF signal 156A. For example, the power parameter level "Px1" of the RF signal 156A in state S1 is different (higher or lower) from the power parameter level "Px2" of the RF signal 156A in state S2.

[0109] Note that the power parameter levels "Px1", "Px2", "Py1", and "Py2" are not zero, as shown in Graph 152. Furthermore, the frequency levels "fx1", "fx2", "fy1", and "fy2" are not zero, as shown in Graph 152. Also, the power parameter levels "Px1", "Px2", "Py1", and "Py2" are not zero, as shown in Graph 154. Furthermore, the frequency levels "fx1", "fx2", "fy1", and "fy2" are not zero, as shown in Graph 154.

[0110] Figure 2A is a block diagram showing one embodiment of the plasma tool 200 for achieving peak ion energy enhancement with low angular divergence. The plasma tool 200 is similar to the plasma tool 100, except that the plasma tool 200 relates to the three-state operation of pulse signal 202 rather than the two-state operation of pulse signal 102 (Figure 1A). The plasma tool 200 comprises an RF generator RFGa, another RF generator RFGb, a host computer 116, an IMN 104, a plasma chamber 108, an IMN 112, and a bias RF generator system 114. The RF generator RFGa is a low-frequency RF generator, such as a 400 kHz RF generator, a 2 MHz RF generator, or a 13.56 MHz RF generator. The RF generator RFGb is a high-frequency RF generator. Examples of RF generator RFGb include 2 MHz, 13.56 MHz, 27 MHz, or 60 MHz RF generators. The RF generator RFGb operates at a higher frequency than the RF generator RFGa.

[0111] The RF generator RFGa comprises a DSPx, a power controller PWRS1x, a power controller PWRS2x, another power controller PWRS3x, an automatic frequency regulator AFTS1x, an automatic frequency regulator AFTS2x, another automatic frequency regulator AFTS3x, an RF power supply Psx, and a driver system 118.

[0112] The DSPx is connected to the power controllers PWRS1x, PWRS2x, and PWRS3x, and the automatic frequency adjusters AFTS1x, AFTS2x, and AFTS3x. Furthermore, the power controllers PWRS1x, PWRS2x, and PWRS3x, as well as the automatic frequency adjusters AFTS1x, AFTS2x, and AFTS3x, are connected to the driver system 118. The driver system 118 is connected to the RF power supply Psx, which is connected to the RF cable 124 via the output of the RF generator RFGa.

[0113] The RF generator RFGb comprises a DSPy, a power controller PWRS1y, a power controller PWRS2y, another power controller PWRS3y, an automatic frequency adjuster AFTS1y, and an automatic frequency adjuster AFT2y. The RF generator RFGb further comprises another automatic frequency adjuster AFTS3y, an RF power supply Psy, and a driver system 128. The DSPy is connected to the power controllers PWRS1y, PWRS2y, and PWRS3y, and to the automatic frequency adjusters AFTS1y, AFTS2y, and AFTS3y. Furthermore, the power controllers PWRS1y, PWRS2y, and PWRS3y, as well as the automatic frequency adjusters AFTS1y, AFTS2y, and AFTS3y, are connected to the driver system 128. 28 It is connected to driver system 1. 28 It is connected to the RF power supply Psy, which is connected to the RF cable 130 via the output of the RF generator RFGb.

[0114] The control circuit of processor 132 is used to generate pulse signals 202 (e.g., TTL signals, digital pulse signals, square waves, pulse signals, etc., with three duty cycles for three states S1 to S3). An example of the control circuit of processor 132 used to generate pulse signals 202 includes a TTL circuit.

[0115] The pulse signal 202 has states S1, S2, and S3. For example, state S1 of the pulse signal 202 has a logic level of "1" during part of the clock cycle of the clock signal 204 and a logic level of "0" during another part of the clock cycle; state S2 of the pulse signal 202 has a logic level of "1" during part of the clock cycle and a logic level of "0" during another part of the clock cycle; and state S3 of the pulse signal 202 has a logic level of "1" during part of the clock cycle and a logic level of "0" during another part of the clock cycle. In various embodiments, states S1, S2, and S3 are executed once during the clock cycle of the pulse signal 202 and repeated over multiple clock cycles. For example, one clock cycle has states S1 to S3, and another clock cycle of the clock signal 204 has states S1 to S3. To illustrate, state S1 is executed during part of the clock cycle, state S2 is executed during another part of the clock cycle, and state S3 is executed during the remainder of the clock cycle.

[0116] In some embodiments, each of states S1 to S3 has a duty cycle of 1 / 3. In some embodiments, each of states S1 to S3 has a duty cycle different from any of the remaining duty cycles of states S1 to S3. For example, state S1 has a duty cycle of a%, state S2 has a duty cycle of b%, and state S3 has a duty cycle of (100-ab)%, where a and b are positive integers and a is a different number from b.

[0117] In various embodiments, instead of the control circuit of the processor 132 for generating the pulse signal 202, a clock source (e.g., a crystal oscillator) is used to generate an analog clock signal, which is converted into a digital signal similar to the pulse signal 202 by an analog-to-digital converter. For example, a crystal oscillator is formed to oscillate in an electric field by applying a voltage to electrodes near the crystal oscillator. To illustrate, the crystal oscillator oscillates at a first frequency during the first part of the clock cycle of the clock signal 204, at a second frequency during the second part of the clock cycle of the clock signal 204, and at a third frequency during the remainder of the clock cycle of the clock signal 204. The third frequency is different from the second frequency, and the second frequency is different from the first frequency. In some embodiments, the first frequency is the same as the second frequency but different from the third frequency. In various embodiments, the first frequency is the same as the third frequency but different from the second frequency. In various embodiments, instead of the processor 132, a digital clock source generates the pulse signal 202.

[0118] The processor 132 accesses recipes from the memory device 144. Examples of recipes include power parameter setpoints applied to RF generator RFGa during state S1, power parameter setpoints applied to RF generator RFGa during state S2, power parameter setpoints applied to generator RFGa during state S3, frequency setpoints applied to RF generator RFGa during state S1, frequency setpoints applied to RF generator RFGa during state S2, frequency setpoints applied to RF generator RFGa during state S3, power parameter setpoints applied to RF generator RFGb during state S1, power parameter setpoints applied to RF generator RFGb during state S2, power parameter setpoints applied to RF generator RFGb during state S3, frequency setpoints applied to RF generator RFGb during state S1, frequency setpoints applied to RF generator RFGb during state S2, frequency setpoints applied to RF generator RFGb during state S3, the chemistry of one or more processing gases, or a combination thereof.

[0119] The processor 132 sends an instruction to the DSPx via cable 146 along with a pulse signal 202. The instruction sent to the DSPx via cable 146 includes information about the pulse signal 202, a power parameter setpoint applied to the RF generator RFGa during state S1, a power parameter setpoint applied to the RF generator RFGa during state S2, a power parameter setpoint applied to the RF generator RFGa during state S3, a frequency setpoint applied to the RF generator RFGa during state S1, a frequency setpoint applied to the RF generator RFGa during state S2, and a frequency setpoint applied to the RF generator RFGa during state S3. The information about the pulse signal 202 indicates to the DSPx that the RF signal generated by the RF generator RFGa transitions from state S1 to state S2 at clock cycle transition time ts1, from state S2 to state S3 at clock cycle transition time ts2, and from state S3 to state S1 at clock cycle transition time ts3. The DSPx determines from the instructions that the power parameter setpoint for state S1 is applied during state S1 of the pulse signal 202, the power parameter setpoint for state S2 is applied during state S2 of the pulse signal 202, the power parameter setpoint for state S3 is applied during state S3 of the pulse signal 202, the frequency setpoint for state S1 is applied during state S1 of the pulse signal 202, the frequency setpoint for state S2 is applied during state S2 of the pulse signal 202, and the frequency setpoint for state S3 is applied during state S3 of the pulse signal 202. Furthermore, the DSPx determines from the instructions and pulse signal 202 that the RF signal generated by the RF generator RFGa transitions from state S1 to state S2 at clock cycle transition time ts1, from state S2 to state S3 at clock cycle transition time ts2, and from state S3 to state S1 at clock cycle transition time ts3. The transition times ts1 to ts3 are repeated in each clock cycle of the clock signal 204.

[0120] At the clock cycle transition time ts3 of clock signal 204, DSPx transmits the power parameter setpoint for state S1 to power controller PWRS1x. Similarly, at the clock cycle transition time ts1 of clock signal 204, DSPx transmits the power parameter setpoint for state S2 to power controller PWRS2x. Also, at the clock cycle transition time ts2 of clock signal 204, DSPx transmits the power parameter setpoint for state S3 to power controller PWRS3x. Furthermore, at the clock cycle transition time ts3, DSPx transmits the frequency setpoint for state S1 to automatic frequency adjuster AFTS1x. Also, at the clock cycle transition time ts1, DSPx transmits the frequency setpoint for state S2 to automatic frequency adjuster AFTS2x. Furthermore, at the clock cycle transition time ts2, DSPx transmits the frequency setpoint for state S3 to automatic frequency adjuster AFTS3x.

[0121] Upon receiving a power parameter setpoint for state S1, the power controller PWRS1x determines the amount of current corresponding to the power parameter setpoint for state S1. Based on the amount of current generated by the driver system 118 during state S1, the power controller PWRS1x generates a command signal and transmits it to the driver system 118. During state S1, in response to receiving the command signal, the driver system 118 generates a current signal with the amount of current and transmits it to the RF power supply Psx. After receiving the current signal, the RF power supply Psx generates an RF signal with the power parameter setpoint for state S1 and supplies this RF signal to the output of the RF generator RFGa and to the input of the IMN104 via the RF cable 124. The power parameter setpoint for state S1 is maintained by the RF power supply Psx of the RF generator RFGa during state S1.

[0122] Similarly, upon receiving a power parameter setpoint for state S2, the power controller PWRS2x determines the amount of current corresponding to the power parameter setpoint for state S2. Based on the amount of current generated by the driver system 118 during state S2, the power controller PWRS2x generates a command signal and transmits it to the driver system 118. During state S2, in response to receiving the command signal, the driver system 118 generates a current signal with the amount of current and transmits it to the RF power supply Psx. After receiving the current signal, the RF power supply Psx generates an RF signal with the power parameter setpoint for state S2 and supplies that RF signal to the output of the RF generator RFGa and to the input of the IMN 104 via the RF cable 124. The power parameter setpoint for state S2 is maintained by the RF power supply Psx of the RF generator RFGa during state S2.

[0123] Furthermore, upon receiving a power parameter setpoint for state S3, the power controller PWRS3x determines the amount of current corresponding to the power parameter setpoint for state S3. Based on the amount of current generated by the driver system 118 during state S3, the power controller PWRS3x generates a command signal and transmits it to the driver system 118. During state S3, in response to receiving the command signal, the driver system 118 generates a current signal with the amount of current and transmits it to the RF power supply Psx. After receiving the current signal, the RF power supply Psx generates an RF signal with the power parameter setpoint for state S3 and supplies this RF signal to the output of the RF generator RFGa and to the input of the IMN 104 via the RF cable 124. The power parameter setpoint for state S3 is maintained by the RF power supply Psx of the RF generator RFGa during state S3.

[0124] Furthermore, upon receiving a frequency setpoint for state S1, the automatic frequency regulator AFTS1x determines the amount of current corresponding to the frequency setpoint for state S1. Based on the amount of current generated by the driver system 118 during state S1, the automatic frequency regulator AFTS1x generates a command signal and transmits it to the driver system 118. During state S1, in response to receiving the command signal, the driver system 118 generates a current signal with the amount of current and transmits it to the RF power supply Psx. After receiving the current signal, the RF power supply Psx generates an RF signal with a frequency setpoint for state S1 and supplies this RF signal to the output of the RF generator RFGa and to the input of the IMN104 via the RF cable 124. The frequency setpoint for state S1 is maintained by the RF power supply Psx of the RF generator RFGa during state S1. The RF signal with the power parameter setpoint and the frequency setpoint for state S1 is the RF signal generated by the RF generator RFGa during state S1.

[0125] Similarly, upon receiving a frequency setpoint for state S2, the automatic frequency regulator AFTS2x determines the amount of current corresponding to the frequency setpoint for state S2. Based on the amount of current generated by the driver system 118 during state S2, the automatic frequency regulator AFTS2x generates a command signal and transmits it to the driver system 118. During state S2, in response to receiving the command signal, the driver system 118 generates a current signal with the amount of current and transmits it to the RF power supply Psx. After receiving the current signal, the RF power supply Psx generates an RF signal with a frequency setpoint for state S2 and supplies this RF signal to the output of the RF generator RFGa and to the input of the IMN 104 via the RF cable 124. The frequency setpoint for state S2 is maintained by the RF power supply Psx of the RF generator RFGa during state S2. The RF signal with the power parameter setpoint and the frequency setpoint for state S2 is the RF signal generated by the RF generator RFGa during state S2.

[0126] Furthermore, upon receiving a frequency setpoint for state S3, the automatic frequency regulator AFTS3x determines the amount of current corresponding to the frequency setpoint for state S3. Based on the amount of current generated by the driver system 118 during state S3, the automatic frequency regulator AFTS3x generates a command signal and transmits it to the driver system 118. During state S3, in response to receiving the command signal, the driver system 118 generates a current signal with the amount of current and transmits it to the RF power supply Psx. After receiving the current signal, the RF power supply Psx generates an RF signal with a frequency setpoint for state S3 and supplies this RF signal to the output of the RF generator RFGa and to the input of the IMN 104 via the RF cable 124. The frequency setpoint for state S3 is maintained by the RF power supply Psx of the RF generator RFGa during state S3. The RF signal with the power parameter setpoint and the frequency setpoint for state S3 is the RF signal generated by the RF generator RFGa during state S3.

[0127] The processor 132 sends an instruction to the DSPy along with the pulse signal 202 via the cable 148. The instruction sent to the DSPy via the cable 148 includes information about the pulse signal 202, a power parameter setpoint applied to the RF generator RFGb during state S1, a power parameter setpoint applied to the RF generator RFGb during state S2, a power parameter setpoint applied to the RF generator RFGb during state S3, a frequency setpoint applied to the RF generator RFGb during state S1, a frequency setpoint applied to the RF generator RFGb during state S2, and a frequency setpoint applied to the RF generator RFGb during state S3. The information about the pulse signal 202 indicates to the DSPy that the RF signal generated by the RF generator RFGb transitions from state S1 to state S2 at the clock cycle transition time ts1 of the clock signal 204, transitions from state S2 to state S3 at the clock cycle transition time ts2, and transitions from state S3 to state S1 at the clock cycle transition time ts3. DSPy parses the instruction and determines from the instruction that the power parameter setpoint for state S1 is applied to pulse signal 202 in state S1, the power parameter setpoint for state S2 is applied to pulse signal 202 in state S2, the power parameter setpoint for state S3 is applied to pulse signal 202 in state S3, the frequency setpoint for state S1 is applied to pulse signal 202 in state S1, the frequency setpoint for state S2 is applied to pulse signal 202 in state S2, and the frequency setpoint for state S3 is applied to pulse signal 202 in state S3. Furthermore, DSPy determines from the instruction that the RF signal generated by RF generator RFGb transitions from state S1 to state S2 at clock cycle transition time ts1, from state S2 to state S3 at clock cycle transition time ts2, and from state S3 to state S1 at clock cycle transition time ts3.

[0128] At the transition time ts3 of the clock cycle of clock signal 204, DSPy transmits the power parameter setpoint for state S1 to power controller PWRS1y. Similarly, at the transition time ts1 of the clock cycle of clock signal 204, DSPy transmits the power parameter setpoint for state S2 to power controller PWRS2y. Also, at the transition time ts2 of the clock cycle of clock signal 204, DSPy transmits the power parameter setpoint for state S3 to power controller PWRS3y. Furthermore, at the transition time ts3 of the clock cycle, DSPy transmits the frequency setpoint for state S1 to automatic frequency adjuster AFTS1y. Also, at the transition time ts1 of the clock cycle, DSPy transmits the frequency setpoint for state S2 to automatic frequency adjuster AFTS2y. Furthermore, at the transition time ts2 of the clock cycle, DSPy transmits the frequency setpoint for state S3 to automatic frequency adjuster AFTS3y.

[0129] Upon receiving a power parameter setpoint for state S1, the power controller PWRS1y determines the amount of current corresponding to the power parameter setpoint for state S1. Based on the amount of current generated by the driver system 128 during state S1, the power controller PWRS1y generates a command signal and transmits it to the driver system 128. During state S1, in response to receiving the command signal, the driver system 128 generates a current signal with the amount of current and transmits it to the RF power supply Psy. After receiving the current signal, the RF power supply Psy generates an RF signal with the power parameter setpoint for state S1 and supplies this RF signal to the output of the RF generator RFGb and to other inputs of the IMN104 via the RF cable 130. The power parameter setpoint for state S1 is maintained by the RF power supply Psy during state S1.

[0130] Similarly, upon receiving a power parameter setpoint for state S2, the power controller PWRS2y determines the amount of current corresponding to the power parameter setpoint for state S2. Based on the amount of current generated by the driver system 128 during state S2, the power controller PWRS2y generates a command signal and transmits it to the driver system 128. During state S2, in response to receiving the command signal, the driver system 128 generates a current signal with the amount of current and transmits it to the RF power supply Psy. After receiving the current signal, the RF power supply Psy generates an RF signal with the power parameter setpoint for state S2 and supplies that RF signal to the output of the RF generator RFGb and to other inputs of the IMN 104 via the RF cable 130. The power parameter setpoint for state S2 is maintained by the RF power supply Psy during state S2.

[0131] Furthermore, upon receiving a power parameter setpoint for state S3, the power controller PWRS3y determines the amount of current corresponding to the power parameter setpoint for state S3. Based on the amount of current generated by the driver system 128 during state S3, the power controller PWRS3y generates a command signal and transmits it to the driver system 128. During state S3, in response to receiving the command signal, the driver system 128 generates a current signal with the amount of current and transmits it to the RF power supply Psy. After receiving the current signal, the RF power supply Psy generates an RF signal with the power parameter setpoint for state S3 and supplies that RF signal to the output of the RF generator RFGb and to other inputs of the IMN 104 via the RF cable 130. The power parameter setpoint for state S3 is maintained by the RF power supply Psy during state S3.

[0132] Furthermore, upon receiving a frequency setpoint for state S1, the automatic frequency regulator AFTS1y determines the amount of current corresponding to the frequency setpoint for state S1. Based on the amount of current generated by the driver system 128 during state S1, the automatic frequency regulator AFTS1y generates a command signal and transmits it to the driver system 128. During state S1, in response to receiving the command signal, the driver system 128 generates a current signal with the amount of current and transmits it to the RF power supply Psy. After receiving the current signal, the RF power supply Psy generates an RF signal with a frequency setpoint for state S1 and supplies this RF signal to the output of the RF generator RFGb and to other inputs of the IMN104 via the RF cable 130. The frequency setpoint for state S1 is maintained by the RF power supply Psy during state S1. The RF signal with the power parameter setpoint and the frequency setpoint for state S1 is the RF signal generated by the RF generator RFGb during state S1.

[0133] Similarly, upon receiving a frequency setpoint for state S2, the automatic frequency adjuster AFTS2y determines the amount of current corresponding to the frequency setpoint for state S2. Based on the amount of current generated by the driver system 128 during state S2, the automatic frequency adjuster AFTS2y generates a command signal, and the driver system 128 receives that command signal. 28 It sends to the following: During state S2, in response to the receipt of the command signal, the driver system 1 28 It generates a current signal with that amount of current and transmits it to the RF power supply Psy. After receiving the current signal, the RF power supply Psy generates an RF signal with a frequency setpoint for state S2 and supplies that RF signal to the output of the RF generator RFGb and to the other inputs of the IMN104 via the RF cable 130. The frequency setpoint for state S2 is maintained by the RF power supply Psy during state S2. The RF signal with the power parameter setpoint and the frequency setpoint for state S2 is the RF signal generated by the RF generator RFGb during state S2.

[0134] Furthermore, upon receiving a frequency setpoint for state S3, the automatic frequency regulator AFTS3y determines the amount of current corresponding to the frequency setpoint for state S3. Based on the amount of current generated by the driver system 128 during state S3, the automatic frequency regulator AFTS3y generates a command signal and transmits it to the driver system 128. During state S3, in response to receiving the command signal, the driver system 128 generates a current signal with the amount of current and transmits it to the RF power supply Psy. After receiving the current signal, the RF power supply Psy generates an RF signal with a frequency setpoint for state S3 and supplies this RF signal to the output of the RF generator RFGb and to other inputs of the IMN 104 via the RF cable 130. The frequency setpoint for state S3 is maintained by the RF power supply Psy during state S3. The RF signal with the power parameter setpoint and the frequency setpoint for state S3 is the RF signal generated by the RF generator RFGb during state S3.

[0135] The inputs of IMN104 receive an RF signal generated by RF generator RFGa via RF cable 124 from the output of RF generator RFGa, and another RF signal generated by RF generator RFGb via RF cable 130 from the output of RF generator RFGb. The impedance of the load connected to the output of IMN104 is matched with the impedance of the source connected to the input of IMN104 to generate a modulated RF signal at the output of IMN104. The modulated RF signal is transmitted to the upper electrode 106 via RF transmission line 126. When one or more processing gases are supplied between the upper electrode 108 and the chuck 110, the modulated RF signal is transmitted to the lower electrode At the extreme A power RF signal is supplied to the chuck 110, and one or more processing gases are ignited to generate plasma in the plasma chamber 108, or the plasma is maintained in the plasma chamber 108.

[0136] In various embodiments, the power controllers PWRS1x, PWRS2x, and PWRS3x, as well as the automatic frequency regulators AFTS1x, AFTS2x, and AFTS3x, are modules (e.g., parts) of a computer program executed by the DSPx of the RF generator RFGa.

[0137] In some embodiments, the power controllers PWRS1x, PWRS2x, and PWRS3x, as well as the automatic frequency regulators AFTS1x, AFTS2x, and AFTS3x, are separate integrated circuits connected to the integrated circuit of the DSPx of the RF generator RFGa. For example, power controller PWRS1x is the first integrated circuit of the RF generator RFGa, power controller PWRS2x is the second integrated circuit of the RF generator RFGa, power controller PWRS3x is the third integrated circuit of the RF generator RFGa, automatic frequency regulator AFTS1x is the fourth integrated circuit of the RF generator RFGa, automatic frequency regulator AFTS2x is the fifth integrated circuit of the RF generator RFGa, automatic frequency regulator AFTS3x is the sixth integrated circuit of the RF generator RFGa, and the DSPx is the seventh integrated circuit of the RF generator RFGa. Each of the first to sixth integrated circuits of the RF generator RFGa is connected to the seventh integrated circuit of the RF generator RFGa.

[0138] In some embodiments, the power controllers PWRS1y, PWRS2y, and PWRS3y, as well as the automatic frequency adjusters AFTS1y, AFTS2y, and AFTS3y, are modules (e.g., parts) of a computer program executed by the DSPy of the RF generator RFGb.

[0139] In various embodiments, power controllers PWRS1y, PWRS2y, and PWRS3y, as well as automatic frequency regulators AFTS1y, AFTS2y, and AFTS3y, are separate integrated circuits connected to the integrated circuit of the DSPy of the RF generator RFGb. For example, power controller PWRS1y is the first integrated circuit of the RF generator RFGb, power controller PWRS2y is the second integrated circuit of the RF generator RFGb, power controller PWRS3y is the third integrated circuit of the RF generator RFGb, automatic frequency regulator AFTS1y is the fourth integrated circuit of the RF generator RFGb, automatic frequency regulator AFTS2y is the fifth integrated circuit of the RF generator RFGb, automatic frequency regulator AFTS3y is the sixth integrated circuit of the RF generator RFGb, and DSPy is the seventh integrated circuit of the RF generator RFGb. Each of the first to sixth integrated circuits of the RF generator RFGb is connected to the seventh integrated circuit of the RF generator RFGb.

[0140] In some embodiments, an example of RF signal state S3 includes a power parameter setpoint for state S3 and a frequency setpoint for state S3. The power parameter setpoint for state S3 is the operating power parameter setpoint, which is the power parameter level (such as the envelope or amplitude from zero to peak) of the amount of energy or voltage of the RF signal in state S3. The frequency setpoint for state S3 is the operating frequency setpoint, which is the frequency level (such as the envelope or amplitude from zero to peak) of the frequency value of the RF signal in state S3.

[0141] In various embodiments, the clock signal 204 is generated by the processor 132 or a clock source (as exemplified above). In some embodiments, the clock signal 204 is transmitted from the processor 132 to the DSPx of RF generator RFGa via cable 146, and to the DSPy of RF generator RFGb via cable 148.

[0142] In some embodiments, instead of the pulse signal 202 being transmitted from processor 132 to RF generators RFGa and RFGb, the pulse signal 202 is transmitted from a master RF generator to a slave RF generator (such as RF generator RFGb). An example of a master RF generator is RF generator RFGa. For example, the digital signal processor DSPx of RF generator RFGa receives the pulse signal 202 from processor 132 and transmits the pulse signal 202 to the digital signal processor DSPy of RF generator RFGb via a cable (such as a parallel transfer cable, serial transfer cable, or USB cable).

[0143] Figure 2B shows the states S1, S2, and S of the RF signals generated and supplied by RF generator RFGa (e.g., RF signal 216A) and RF signals generated and supplied by RF generator RFGb (e.g., RF signal 216B). 3 To illustrate this, Graphs 210, 212, and 214 show embodiments. Graph 210 plots the logic level of the clock signal 204 against time t. Similarly, Graph 212 plots the logic level of the pulse signal 202 against time t.

[0144] Period t1 is the period within the clock cycle of clock signal 204 during which state S1 of the RF signals generated by RF generators RFGa and RFGb is maintained. Similarly, period t2 is the period within the clock cycle of clock signal 204 during which state S2 of the RF signals generated by RFGa and RFGb is maintained. Also, period t3 is the period within the clock cycle of clock signal 204 during which state S3 of the RF signals generated by RFGa and RFGb is maintained. For example, period t1 occupies a portion of the clock cycle, period t2 occupies another portion of the clock cycle, and period t3 occupies the remainder of the clock cycle. The clock cycle of clock signal 204 consists of periods t1 to t3 and is repeated to generate multiple clock cycles of clock signal 204.

[0145] During period t1, the pulse signal 202 pulses from logic level 1 to logic level 0. Logic level 1 is an example of a high logic level, and logic level 0 is an example of a low logic level. During period t1, the RF signals generated by RF generators RFGa and RFGb are controlled to maintain state S1.

[0146] During the transition time ts1 of the clock cycle in which pulse signal 202 transitions from logic level 0 to logic level 1, the RF signals generated by RF generators RFGa and RFGb are controlled to transition from state S1 to state S2. The transition time ts1 occurs after period t1.

[0147] Period t2 occurs after the transition time ts1. During period t2, the pulse signal 202 pulses from logic level 1 to logic level 0. Furthermore, during period t2, the RF signals generated by RF generators RFGa and RFGb are controlled to maintain state S2.

[0148] During the transition time ts2 of the clock cycle in which pulse signal 202 transitions from logic level 0 to logic level 1, the RF signals generated by RF generators RFGa and RFGb are controlled to transition from state S2 to state S3. The transition time ts2 occurs after period t2.

[0149] Period t3 occurs after the transition time ts2. During period t3, the pulse signal 202 pulses from logic level 1 to logic level 0. Furthermore, during period t3, the RF signals generated by RF generators RFGa and RFGb are controlled to maintain state S3.

[0150] During the transition time ts3 of the clock cycle in which pulse signal 102 transitions from logic level 0 to logic level 1, the RF signals generated by RF generators RFGa and RFGb are controlled to transition from state S3 to state S1. The transition time ts3 occurs after period t3. Period t1 is repeated after the transition time ts3 in the subsequent clock cycle of clock signal 204. After period t1 in the subsequent clock cycle of clock signal 204, periods t2 and t3 of the subsequent clock cycle of clock signal 204 follow again. The subsequent clock cycle of clock signal 204 is continuous, such as continuously following or sequentially following the clock cycle of clock signal 204. The transition times ts1 to ts3 and periods t1 to t3 are repeated in the subsequent clock cycle. Furthermore, the transition times ts1 to ts3 and periods t1 to t3 are repeated in the next cycle of clock signal 204 that follows the subsequent cycle.

[0151] The states S1 to S3 of RF signals 216A and 216B repeat in synchronization with each cycle of clock signal 204. For example, states S1 to S3 of RF signal 216A occur during the clock cycle of clock signal 204, and states S1 to S3 of RF signal 216A repeat in subsequent clock cycles of clock signal 204. As another example, states S1 to S3 of RF signal 216B occur during the clock cycle of clock signal 204, and states S1 to S3 of RF signal 216B repeat in subsequent clock cycles of clock signal 204.

[0152] RF signal 216A has a frequency level "f1x" and a power parameter level "P1x" during state S1. Furthermore, RF signal 216B has a frequency level "f1y" that is 0 during state S1 and a power parameter level "P1y" that is 0 during state S1.

[0153] Similarly, RF signal 216A has a frequency level "f2x" and a power parameter level "P2x" in state S2. The frequency level "f2x" is the same as the frequency level "f1x", and the power parameter level "P2x" is the same as the power parameter level "P1x". Furthermore, RF signal 216B has a frequency level "f2y" and a power parameter level "P2y" in state S2. The power parameter level "P2y" is the same as the power parameter level "P2x". The frequency level "f2y" is higher than the frequency level "f2x".

[0154] Similarly, RF signal 216A has a frequency level "f3x" which is 0 during state S3, and a power parameter level "P3x" which is 0 during state S3. Furthermore, RF signal 216B has a frequency level "f3y" which is 0 during state S3, and a power parameter level "P3y" during state S3. The frequency level "f3y" is lower than the frequency level "f2y" and higher than the frequency level "f2x". Furthermore, the power parameter level "P3y" is the same as the power parameter level "P2y".

[0155] Note that the power parameter levels "P1x", "P2x", "P2y", and "P3y" are not zero, as shown in Graph 214. Similarly, the frequency levels "f1x", "f2x", "f2y", and "f3y" are not zero, as shown in Graph 214.

[0156] In some embodiments, the power parameter levels "P2y" and "P3y" are not the same as (lower or higher than) the power parameter levels "P1x" and "P2x".

[0157] In various embodiments, frequency level "f3y" is higher than frequency level "f2y". In some embodiments, frequency level "f3y" is the same as frequency level "f2y". In some embodiments, power parameter level "P2x" is not the same as power parameter level "P1x" (higher or lower). In various embodiments, power parameter level "P2y" is not the same as power parameter level "P3y" (higher or lower).

[0158] In some embodiments, the frequency level "f2x" is not the same as the frequency level "f1x" (it is higher or lower). In various embodiments, the frequency level "f1x" and the power parameter level "P1x" are 0. In some embodiments, the frequency level "f2x" and the power parameter level "P2x" are 0. In some embodiments, the frequency level "f3y" and the power parameter level "P3y" are 0. In some embodiments, the frequency level "f2y" and the power parameter level "P2y" are 0.

[0159] In some embodiments, each of states S1 to S3 of the RF signal 216A or RF signal 216B has a duty cycle of 1 / 3. In some embodiments, each of states S1 to S3 of the RF signal (such as RF signal 216A or RF signal 216B) has a duty cycle different from the duty cycle of any of the other states of the RF signal S1 to S3. For example, state S1 of the RF signal has a duty cycle of a%, state S2 of the RF signal has a duty cycle of b%, and state S3 of the RF signal has a duty cycle of (100-ab)%. Here, the duty cycle of state S1 of the RF signal is different from the duty cycle of state S2 of the RF signal. As another example, the duty cycle of state S1 of the RF signal is different from the duty cycle of state S2 of the RF signal, and the duty cycle of state S1 of the RF signal is the same as the duty cycle of state S3 of the RF signal. As yet another example, the duty cycle of state S1 of the RF signal is different from the duty cycle of state S3 of the RF signal. As yet another example, the duty cycle of RF signal state S1 is different from the duty cycle of RF signal state S3, while the duty cycle of RF signal state S1 is the same as the duty cycle of RF signal state S2. As yet another example, the duty cycle of RF signal state S2 is different from the duty cycle of RF signal state S3. As yet another example, the duty cycle of RF signal state S2 is different from the duty cycle of RF signal state S3, while the duty cycle of RF signal state S2 is the same as the duty cycle of RF signal state S1.

[0160] Note that the RF generator RFGa is controlled to operate at frequency level "f2x" during state S2. The power parameter of the RF signal generated by RF generator RFGa during state S2 is added to the power parameter of the RF signal generated by RF generator RFGb during state S3. The plasma sheath 123 of the plasma formed in plasma chamber 108 acts as a capacitor, which charges during state S2 from power parameter level "P2x" associated with frequency level "f2x" and discharges during state S3. The addition of the power parameter and the discharge of the capacitor increase the ionic energy of the plasma ions in plasma chamber 108 during state S3 and decrease the angular divergence of ionic energy during state S3. For example, the vertical orientation of the plasma in plasma chamber 108 increases during state S3 along with the addition of the power parameter during state S3.

[0161] Figure 2C shows the states S1, S2, and S of the RF signal generated and supplied by RF generator RFGa (e.g., RF signal 220A), and the RF signal generated and supplied by RF generator RFGb (e.g., RF signal 220B). 3 To illustrate this, Graphs 210, 212, and 218 show embodiments.

[0162] The states S1-S3 of RF signals 220A and 220B repeat in synchronization with each cycle of clock signal 204. For example, states S1-S3 of RF signal 220A occur during the clock cycle of clock signal 204, and states S1-S3 of RF signal 220A repeat in subsequent clock cycles of clock signal 204. As another example, states S1-S3 of RF signal 220B occur during the clock cycle of clock signal 204, and states S1-S3 of RF signal 220B repeat in subsequent clock cycles of clock signal 204.

[0163] RF signal 220A has a frequency level "f1x" that is 0 during state S1 and a power parameter level "P1x" that is 0 during state S1. Furthermore, RF signal 220B has a frequency level "f1y" that is 0 during state S1 and a power parameter level "P1y" that is 0 during state S1.

[0164] Similarly, RF signal 220A has a frequency level "f2x" and a power parameter level "P2x" in state S2. Furthermore, RF signal 220B has a frequency level "f2y" and a power parameter level "P2y" in state S2. The power parameter level "P2y" is the same as the power parameter level "P2x", and the frequency level "f2y" is higher than the frequency level "f2x".

[0165] Similarly, RF signal 220A has a frequency level "f3x" and a power parameter level "P3x" during state S3. The frequency level "f3x" is higher than the frequency level "f2x", and the power parameter level "P3x" is the same as the power parameter level "P2x". Furthermore, RF signal 220B has a frequency level "f3y" and a power parameter level "P3y" during state S3. The frequency level "f3y" is lower than the frequency level "f2y". Furthermore, the power parameter level "P3y" is the same as the power parameter level "P2y". Also, the frequency level "f3x" is higher than the frequency level "f2x".

[0166] In some embodiments, the power parameter levels "P2y" and "P3y" are not the same as (lower or higher than) the power parameter levels "P2x" and "P3x".

[0167] In various embodiments, the frequency level "f3x" is the same as the frequency level "f2x". In some embodiments, the frequency level "f3x" is lower than the frequency level "f2x". In various embodiments, the frequency level "f3y" is higher than the frequency level "f2y". In some embodiments, the frequency level "f3y" is the same as the frequency level "f2y".

[0168] In some embodiments, the power parameter level "P2x" is not the same as (higher or lower than) the power parameter level "P3x". In various embodiments, the power parameter level "P2y" is not the same as (higher or lower than) the power parameter level "P3y".

[0169] In some embodiments, the frequency level "f2x" and the power parameter level "P2x" are 0. In various embodiments, the frequency level "f3x" and the power parameter level "P3x" are 0. In some embodiments, the frequency level "f2y" and the power parameter level "P2y" are 0. In some embodiments, the frequency level "f3y" and the power parameter level "P3y" are 0.

[0170] In some embodiments, each of states S1 to S3 of RF signal 220A or RF signal 220B has a duty cycle of 1 / 3. In some embodiments, each of states S1 to S3 of the RF signal (such as RF signal 220A or RF signal 220B) has a duty cycle different from the duty cycle of any of the other states of RF signal S1 to S3. For example, RF signal state S1 has a duty cycle of a%, RF signal state S2 has a duty cycle of b%, and RF signal state S3 has a duty cycle of (100-ab)%.

[0171] Note that the RF generator RFGa is controlled to operate at frequency level "f2x" during state S2. The power parameter of the RF signal generated by RF generator RFGa during state S2 is added to the power parameter of the RF signal generated by RF generator RFGb during state S3. The plasma sheath 123 of the plasma formed in plasma chamber 108 acts as a capacitor, which charges during state S2 from power parameter level "P2x" associated with frequency level "f2x" and discharges during state S3. The addition of the power parameter and the discharge of the capacitor increase the ionic energy of the plasma ions in plasma chamber 108 during state S3 and decrease the angular divergence of ionic energy during state S3. For example, the vertical orientation of the plasma in plasma chamber 108 increases during state S3 along with the addition of the power parameter during state S3.

[0172] Note that the power parameter levels "P2x", "P3x", "P2y", and "P3y" are not zero, as shown in Graph 218. Furthermore, the frequency levels "f2x", "f3x", "f2y", and "f3y" are not zero, as shown in Graph 218.

[0173] Figure 2D shows the states S1, S2, and S of the RF signals generated and supplied by RF generator RFGa (e.g., RF signal 224A), and the RF signals generated and supplied by RF generator RFGb (e.g., RF signal 224B). 3 To illustrate this, Graphs 210, 212, and 222 show embodiments.

[0174] The states S1-S3 of RF signals 224A and 224B repeat in synchronization with each cycle of clock signal 204. For example, states S1-S3 of RF signal 224A occur during the clock cycle of clock signal 204, and states S1-S3 of RF signal 224A repeat in subsequent clock cycles of clock signal 204. As another example, states S1-S3 of RF signal 224B occur during the clock cycle of clock signal 204, and states S1-S3 of RF signal 224B repeat in subsequent clock cycles of clock signal 204.

[0175] RF signal 224A has a frequency level "f1x" that is 0 during state S1 and a power parameter level "P1x" that is 0 during state S1. Furthermore, RF signal 224B has a frequency level "f1y" that is 0 during state S1 and a power parameter level "P1y" that is 0 during state S1.

[0176] Similarly, RF signal 224A has a frequency level "f2x" and a power parameter level "P2x" that is 0 during state S2. Furthermore, RF signal 224B has a frequency level "f2y" and a power parameter level "P2y" during state S2. The frequency level "f2y" of RF signal 224B is higher than the frequency level "f2x" of RF signal 224A during state S2, and the power parameter level "P2y" of RF signal 224B is the same as the power parameter level "P2x" of RF signal 224A during state S2.

[0177] Similarly, RF signal 224A has a frequency level "f3x" which is 0 in state S3, and a power parameter level "P3x" which is 0 in state S3. Furthermore, RF signal 224B has a frequency level "f3y" which is 0 in state S3, and a power parameter level "P3y" in state S3. The frequency level "f3y" of RF signal 224B in state S3 is the same as the frequency level "f2y" of RF signal 224B in state S2. Furthermore, the power parameter level "P3y" of RF signal 224B in state S3 is the same as the power parameter level "P2y" of RF signal 224B in state S2.

[0178] In some embodiments, the power parameter levels "P2y" and "P3y" are not the same as (lower or higher than) the power parameter level "P2x".

[0179] In various embodiments, the frequency level "f3y" is not the same as the frequency level "f2y" (it is higher or lower). In some embodiments, the frequency level "f2y" and the power parameter level "P2y" are 0. In various embodiments, the frequency level "f3y" and the power parameter level "P3y" are 0.

[0180] In some embodiments, each of states S1 to S3 of the RF signal 224A or RF signal 224B has a duty cycle of 1 / 3. In some embodiments, each of states S1 to S3 of the RF signal (such as RF signal 224A or RF signal 224B) has a duty cycle different from the duty cycle of any of the other states of the RF signal S1 to S3. For example, state S1 of the RF signal has a duty cycle of a%, state S2 of the RF signal has a duty cycle of b%, and state S3 of the RF signal has a duty cycle of (100-ab)%, where a is an integer different from b.

[0181] Note that the RF generator RFGa is controlled to operate at frequency level "f2x" during state S2. The power parameter of the RF signal generated by RF generator RFGa during state S2 is added to the power parameter of the RF signal generated by RF generator RFGb during state S3. The plasma sheath 223 of the plasma formed in plasma chamber 108 acts as a capacitor, which charges during state S2 from power parameter level "P2x" associated with frequency level "f2x" and discharges during state S3. The addition of the power parameter and the discharge of the capacitor increase the ionic energy of the plasma ions in plasma chamber 108 during state S3 and decrease the angular divergence of ionic energy during state S3. For example, the vertical orientation of the plasma in plasma chamber 108 increases during state S3 along with the addition of the power parameter during state S3.

[0182] Note that the power parameter levels "P2x", "P2y", and "P3y" are not zero, as shown in Graph 222. Furthermore, the frequency levels "f2x", "f2y", and "f3y" are not zero, as shown in Graph 222.

[0183] Figure 3 shows several embodiments of graphs 302A and 302B to illustrate how pulsing the frequency level of an RF signal generated by a frequency-pulsed RF generator (such as RF generator RFGx or RF generator RFGa) increases the peak energy of plasma ions incident on the surface of the substrate 122 (such as the surface of a channel in the substrate 122). Each graph 302a and 302b plots the IEAD, which is a plot of the energy of plasma ions (measured in electron volts (eV)) against an angle θ (degrees) measured in a channel formed in the substrate 122. Graph 302a plots the energy when the frequency level of the RF generator is not pulsed (e.g., operating in continuous wave (CW) mode). Graph 302b plots the energy when a frequency-pulsed RF generator is used. Note that when the frequency level of the RF generator RFGx or RFGa is pulsed between multiple states, the peak ion energy of the plasma ions in the plasma chamber 108 increases compared to the peak ion energy of the plasma ions when a CW mode RF generator is used. Furthermore, when the frequency level of the RF generator RFGx or RFGa is pulsed between multiple states, the angular divergence of the plasma ions in the channel decreases compared to the angular divergence of the plasma ions when a CW mode RF generator is used. Additionally, note that the amount of bias voltage supplied by the bias RF generator system 114 is the same (e.g., 300 volts) regardless of whether a frequency-pulsed RF generator or a CW mode RF generator is used, as shown in graphs 302a and 302b. The increase in peak ion energy and decrease in angular divergence increase the etching rate of the substrate 122, and the bias voltage does not need to be increased for the increased etching rate. For example, the bias voltage of one or more RF signals generated and supplied by the bias RF generator system 114 is constant when the frequency level of the RF generator RFGx or RFGa is pulsed.As another example, the bias voltage of one or more RF signals generated and supplied by the bias RF generator system 114 is substantially constant (e.g., within a predetermined threshold, within 5-10% of a predetermined value, etc.) when the frequency level of the RF generator RFGx or RFGa is pulsed.

[0184] Figure 4 shows one embodiment of Graph 400 to illustrate how the angular distribution of plasma ions decreases with increasing bias voltage supplied by the bias RF generator system 114. Graph 400 plots the angular distribution (degrees) against the bias voltage. Clearly, as the bias voltage increases from 200 volts to 1600 volts, there is a decrease in the angular divergence distribution and an increase in the etching rate. The angular distribution is also referred to as angular divergence in this specification.

[0185] During etching, the bias voltage is increased to increase the etching rate. As the bias voltage increases, the peak ion energy increases and the angular divergence of plasma ions decreases, so the increased bias voltage etches high aspect ratio features into the substrate 122 faster while maintaining a nearly vertical profile (such as appropriate critical dimensions). However, the increased bias voltage narrows the angular divergence, which increases corrosion of the mask layer, which is the top layer of the substrate 122. Furthermore, increasing the bias voltage introduces complexity to the hardware implementation. Moreover, beyond a certain amount of bias voltage (e.g., above 5 kilovolts), the angular divergence does not narrow further due to the increased thickness of the plasma sheath 123.

[0186] In one embodiment, it should be noted that the amount of bias voltage supplied by the RF generator system 114 is less than 5 kilovolts.

[0187] Figure 5 shows one embodiment of Graph 500 to illustrate that the same angular divergence achieved by increasing the bias voltage can be achieved by pulsing one or more frequency levels of the RF generator RFGx or RFGy or RFGa or RFGb or a combination thereof. For the same bias voltage, when one or more frequency levels of the RF generator (RF generator RFGx or RFGy or RFGa or RFGb or a combination thereof) connected to the upper electrode 106 are pulsed, the angular divergence is reduced compared to when the RF generator operates in CW mode. The reduction in angular divergence increases the etching rate of the substrate 122. When one or more frequency levels of the RF generator RFGx or RFGy or RFGa or RFGb or a combination thereof are pulsed, it is not necessary to increase the bias voltage.

[0188] Figure 6 shows embodiments of Graph 602A and Graph 602B to illustrate the difference in critical dimension (CD) of channels formed within the substrate 122. Graph 602A plots the channel height in nanometers (nm) compared to the channel width in nanometers. The critical dimension of the channel is shown as 22.2 nm in Graph 602A. The critical dimension in Graph 602A is achieved when a CW mode RF generator is used instead of RFGx or RFGy or RFGa or RFGb or a combination thereof. Graph 602B plots the channel height of the substrate 122 in nanometers compared to the channel width of the substrate 122 in nanometers. The critical dimension is shown as 20.1 nm in Graph 602B. The lower critical dimension in Graph 602B compared to Graph 602A is achieved when one or more frequency levels of RFGx or RFGy or RFGa or RFGb or a combination thereof are pulsed. A low critical dimension is achieved when the vertical orientation of plasma ions in the plasma chamber 108 is increased by a decrease in the angular divergence of plasma ions. When the vertical orientation is increased to increase the etching rate, the plasma ions concentrate more on the bottom surface of the channels in the substrate 122.

[0189] Figure 7A is a block diagram showing one embodiment of a plasma tool 700 for achieving peak ion energy enhancement with low angular divergence. The plasma tool 700 comprises an RF generator RFGx1, a host computer 116, an IMN 104, a plasma chamber 108, an IMN 112, and a bias RF generator system 114. Examples of RF generator RFGx1 include low-frequency RF generators such as a 400 kHz RF generator, a 2 MHz RF generator, or a 13.56 MHz RF generator. Other examples of RF generator RFGx1 include high-frequency RF generators such as a 13.56 MHz RF generator, a 27 MHz RF generator, or a 60 MHz RF generator.

[0190] The RF generator RFGx1 comprises a digital signal processor DSPx, a power parameter controller PWRS1x, another power parameter controller PWRS2x, an automatic frequency adjuster AFTx1, an RF power supply Psx, and a driver system 118.

[0191] The DSPx is connected to the power parameter controllers PWRS1x and PWRS2x, and the automatic frequency regulator AFTx1. Furthermore, the power parameter controllers PWRS1x and PWRS2x, as well as AFTx1, are connected to the driver system 118. The RF power supply Psx is connected to the RF cable 124 via the output of the RF generator RFGx1.

[0192] The processor 132 accesses recipes from the memory device 134. Examples of recipes include power parameter setpoints applied to the RF generator RFGx1 during state S1, power parameter setpoints applied to the RF generator RFGx1 during state S2, frequency setpoints applied to the RF generator RFGx1 during states S1 and S2, the chemistry of one or more processing gases, or a combination thereof.

[0193] The processor 132 transmits a command along with the pulse signal 102 to the DSPx of the RF generator RFGx1 via cable 136. The command transmitted to the DSPx of the RF generator RFGx1 via cable 136 includes information about the pulse signal 102, a power parameter setpoint applied to the RF generator RFGx1 during state S1, a power parameter setpoint applied to the RF generator RFGx1 during state S2, and a frequency setpoint applied to the RF generator RFGx1 during states S1 and S2. The information about the pulse signal 102 indicates to the DSPx of the RF generator RFGx1 that the RF signal generated by the RF generator RFGx1 transitions from state S1 to state S2 at the transition time tst1 of the pulse signal 102, and that the RF signal transitions from state S2 to state S1 at the transition time tst2 of the pulse signal 102. The DSPx of the RF generator RFGx1 determines from the command that the power parameter setpoint for state S1 is applied during state S1 of the pulse signal 102, the power parameter setpoint for state S2 is applied during state S2 of the pulse signal 102, and the frequency setpoints for states S1 and S2 are applied during states S1 and S2 of the pulse signal 102. Furthermore, the DSPx of the RF generator RFGx1 determines from the command and the pulse signal 102 that the RF signal generated by the RF generator RFGx1 transitions from state S1 to state S2 at the transition time tst1 of the pulse signal 102, and that the RF signal transitions from state S2 to state S1 at the transition time tst2 of the pulse signal 102.

[0194] At the cycle transition time tst2 of pulse signal 102, the DSPx of RF generator RFGx1 transmits the power parameter setpoint for state S1 to power parameter controller PWRS1x. Similarly, at the cycle transition time tst1 of pulse signal 102, the DSPx transmits the power parameter setpoint for state S2 to power parameter controller PWRS2x. Furthermore, at the cycle transition time tst2 or tst1 of pulse signal 102, the DSPx transmits the frequency setpoint for states S1 and S2 to automatic frequency controller AFTx1.

[0195] Upon receiving a power parameter setpoint for state S1, the power parameter controller PWRS1x of the RF generator RFGx1 determines the amount of current corresponding to the power parameter setpoint for state S1. Based on the amount of current generated by the driver system 118 of the RF generator RFGx1 during state S1, the power parameter controller PWRS1x of the RF generator RFGx1 generates a command signal and transmits the command signal to the driver system 118. During state S1, in response to receiving the command signal, the driver system 118 of the RF generator RFGx1 generates a current signal with the amount of current and transmits it to the RF power supply Psx. After receiving the current signal, the RF power supply Psx of the RF generator RFGx1 generates an RF signal with the power parameter setpoint for state S1 and supplies the RF signal to the output of the RF generator RFGx1 and to the input of the IMN104 via the RF cable 124. The power parameter setpoint for state S1 is maintained by the RF power supply Psx of the RF generator RFGx1 during state S1.

[0196] Similarly, upon receiving a power parameter setpoint for state S2, the power parameter controller PWRS2x of the RF generator RFGx1 determines the amount of current corresponding to the power parameter setpoint for state S2. Based on the amount of current generated by the driver system 118 of the RF generator RFGx1 during state S2, the power parameter controller PWRS2x of the RF generator RFGx1 generates a command signal and transmits the command signal to the driver system 118. During state S2, in response to receiving the command signal, the driver system 118 of the RF generator RFGx1 generates a current signal with the amount of current and transmits it to the RF power supply Psx. After receiving the current signal, the RF power supply Psx of the RF generator RFGx1 generates an RF signal with the power parameter setpoint for state S2 and supplies the RF signal to the output of the RF generator RFGx1 and the input of the IMN 104 via the RF cable 124. The power parameter setpoint for state S2 is maintained by the RF power supply Psx of the RF generator RFGx1 during state S2.

[0197] Furthermore, upon receiving the frequency setpoints for states S1 and S2, the automatic frequency adjuster AFTx1 of the RF generator RFGx1 determines the amount of current corresponding to the frequency setpoint for state S1. Based on the amount of current generated by the driver system 118 during states S1 and S2, the automatic frequency adjuster AFTx1 generates a command signal and transmits that command signal to the driver system 118 of the RF generator RFGx1. During states S1 and S2, in response to receiving the command signal, the driver system 118 of the RF generator RFGx1 generates a current signal with that amount of current and transmits it to the RF power supply Psx of the RF generator RFGx1. After receiving the current signal, the RF power supply Psx of the RF generator RFGx1 generates an RF signal with the frequency setpoint for state S1 and supplies that RF signal to the output of the RF generator RFGx1 and to the input of the IMN 104 via the RF cable 124. The frequency setpoints for states S1 and S2 are maintained by the RF power supply Psx of the RF generator RFGx1 during states S1 and S2. The RF signal having the power parameter setpoint and the frequency setpoint for state S1 is the RF signal generated by the RF generator RFGx1 during state S1. Similarly, the RF signal having the power parameter setpoint and the frequency setpoint for state S2 is the RF signal generated by the RF generator RFGx1 during state S2.

[0198] The input to IMN104 receives the RF signal generated by the RF power supply Psx of the RF generator RFGx1 from the output of RF generator RFGx1 via RF cable 124. The impedance of the load connected to the output of IMN104 is matched with the impedance of the source connected to the input of IMN104 to generate a modulated RF signal at the output of IMN104. Examples of sources connected to the input of IMN104 include RF cable 124 and RF generator RFGx1. The modulated RF signal is transmitted via RF transmission cable 126 to the upper electrode 106 (e.g., the end E1 of the TCP coil).

[0199] When one or more processing gases are supplied between the upper electrode 106 and the chuck 110, a modulated RF signal is supplied to the upper electrode 106, an output RF signal is supplied to the chuck 110, and one or more processing gases are ignited to generate or maintain plasma in the plasma chamber 108.

[0200] In various embodiments, the power parameter controllers PWRS1x and PWRS2x, as well as the automatic frequency regulator AFTx1, are modules (e.g., parts) of a computer program executed by the DSPx of the RF generator RFGx1.

[0201] In some embodiments, the power parameter controllers PWRS1x and PWRS2x, as well as the automatic frequency regulator AFTx1, are separate integrated circuits connected to the integrated circuit of the DSPx of the RF generator RFGx1. For example, the power parameter controller PWRS1x is the first integrated circuit of the RF generator RFGx1, the power parameter controller PWRS2x is the second integrated circuit of the RF generator RFGx1, the automatic frequency regulator AFTx1 is the third integrated circuit of the RF generator RFGx1, and the DSPx is the fourth integrated circuit of the RF generator RFGx1. Each of the first to third integrated circuits of the RF generator RFGx1 is connected to the fourth integrated circuit of the RF generator RFGx1.

[0202] In various embodiments, two RF generators are connected to the IMN104. For example, RF generator RFGy is connected to the IMN104 via RF cable 130 to another input of the IMN104. The IMN104 combines the RF signals received from RF generator RFGx1 and RF generator RFGy, matches the impedance of the source (e.g., RF generator RFGx1, RF generator RFGy, RF cable 124, RF cable 130, etc.) to generate a modulated RF signal at the output of the IMN104.

[0203] Figure 7B shows embodiments of Graphs 140, 710, and 712 to illustrate the pulsation of the power parameters of the RF signals generated by the RF generator RFGx1 in Figure 7A. Graph 710 plots the power parameter levels of the RF signals (e.g., RF signal 714) generated by the RF generator RFGx1 against time t. Furthermore, Graph 712 plots the power parameter levels of the RF signals (e.g., RF signal 716) generated by the RF generator RFGx1 against time t.

[0204] Referring to graphs 140 and 710, in state S1, the RF signal 714 has a power parameter level "Px1" and a frequency level "fx1". Furthermore, at transition time tst1, the RF signal 714 transitions from state S1 to state S2. In state S2, the RF signal 714 has a power parameter level "0" and a frequency level "0". At transition time tst2, the RF signal 714 transitions back from state S2 to state S1.

[0205] Note that the duty cycle of RF signal 714 in state S1 is the same as the duty cycle of RF signal 714 in state S2. For example, the duty cycle of state S1 is 50%, and the duty cycle of state S2 is 50%. RF signal 714 in state S1 accounts for 50% of the cycle of pulse signal 102, and RF signal 714 in state S2 accounts for the remaining 50% of the cycle of pulse signal 102.

[0206] In various embodiments, the duty cycle of state S1 of the RF signal 714 is different from the duty cycle of state S2 of the RF signal 714. For example, the duty cycle of state S1 is 25%, and the duty cycle of state S2 is 75%. State S1 of the RF signal 714 accounts for 25% of the cycles of the pulse signal 102, and state S2 of the RF signal 714 accounts for the remaining 75% of the cycles of the pulse signal 102. As another example, the duty cycle of state S1 is a%, and the duty cycle of state S2 is (100-a)%. State S1 of the RF signal 714 accounts for a% of the cycles of the pulse signal 102, and state S2 of the RF signal 714 accounts for the remaining (100-a)% of the cycles of the pulse signal 102.

[0207] Note that the power parameter level "Px1" and frequency level "fx1" are not zero, as shown in Graph 710.

[0208] Graph 712 is similar to Graph 710, except that RF signals 714 and 716 have different power parameter levels in state S2. For example, RF signal 714 has a power parameter level of "0" in state S2, and RF signal 716 has a power parameter level of "Px2" in state S2. Furthermore, RF signal 716 has a frequency level of "fx2" in state S2, and the frequency level of "fx2" in state S2 is the same as the frequency level of RF signal 716 in state S1, "fx1". RF signal 716 has a power parameter level of "Px1" in state S1.

[0209] Referring to graphs 140 and 712, state S1 of RF signal 716 is the same as state S1 of RF signal 714. For example, the power parameter level "Px1" of RF signal 716 is the same as the power parameter level "Px1" of RF signal 714 in state S1. Also, the frequency level "fx1" of RF signal 716 is the same as the frequency level "fx1" of RF signal 714 in state S1.

[0210] Furthermore, at transition time tst1, RF signal 716 transitions from state S1 to state S2. In state S2, the power parameter level "Px2" of RF signal 716 is higher than the power parameter level Px1 of RF signal 714 in state S1 (which is 0), but lower than the power parameter level "Px1" of RF signal 716 in state S1. At transition time tst2, RF signal 716 transitions back from state S2 to state S1.

[0211] Note that the power parameter levels "Px1" and "Px2," as well as the frequency levels "fx1" and "fx2," are not zero, as shown in Graph 712.

[0212] Note that the duty cycle of RF signal 716 in state S1 is the same as the duty cycle of RF signal 716 in state S2. For example, the duty cycle of RF signal 716 in state S1 is 50%, and the duty cycle of RF signal 716 in state S2 is 50%. RF signal 716 in state S1 accounts for 50% of the cycle of pulse signal 102, and RF signal 716 in state S2 accounts for the remaining 50% of the cycle of pulse signal 102.

[0213] In various embodiments, the duty cycle of RF signal 716 in state S1 is different from the duty cycle of RF signal 716 in state S2. For example, the duty cycle of RF signal 716 in state S1 is 25%, and the duty cycle of RF signal 716 in state S2 is 75%. RF signal 716 in state S1 accounts for 25% of the cycles of pulse signal 102, and RF signal 716 in state S2 accounts for the remaining 75% of the cycles of pulse signal 102. As another example, the duty cycle of RF signal 716 in state S1 is a%, and the duty cycle of RF signal 716 in state S2 is (100-a)%. RF signal 716 in state S1 accounts for a% of the cycles of pulse signal 102, and RF signal 716 in state S2 accounts for the remaining (100-a)% of the cycles of pulse signal 102.

[0214] Note that the RF generator RFGx1 is controlled to operate at power parameter level "Px2" during state S2. The power parameter of the RF signal generated by RF generator RFGx1 during state S2 is added to the power parameter of the RF signal generated by RF generator RFGx1 during state S1. The plasma sheath 123 of the plasma formed in the plasma chamber 108 acts as a capacitor, which charges during state S2 from power parameter level "Px2" associated with frequency level "fx2" and discharges during state S1. The addition of the power parameter and the discharge of the capacitor increase the ionic energy of the plasma ions in the plasma chamber 108 during state S1 and decrease the angular divergence of ionic energy during state S1. For example, the vertical orientation of the plasma in the plasma chamber 108 increases during state S1 along with the addition of the power parameter during state S1.

[0215] Figure 8 shows several embodiments of graphs 800, 802, 804, and 806 to illustrate how the vertical directionality of plasma ions increases with increasing bias voltage. Each graph 800, 802, 804, and 806 plots the energy of plasma ions against the angle measured in the channel formed in the substrate 122. As shown in the figure, the peak ion energy of the plasma in the plasma chamber 108 increases with increasing bias voltage supplied by the bias RF generator system 114. With increasing peak ion energy, the angular divergence of plasma ions in the channel decreases, and the vertical directionality of plasma ions increases.

[0216] Figure 9 shows several embodiments of graphs 902 and 904 to illustrate how pulsing the power parameter level of an RF signal generated by a power parameter pulsed RF generator, e.g., RF generator RFGx or RFGy or RFGa or RFGb or RFGx1, increases the peak energy of plasma ions incident on the surface of substrate 122. Each graph 902 and 904 plots the ion energy distribution function (IEDF), which is a plot of the energy of plasma ions against an angle measured in a channel formed in substrate 122. Graph 902 plots the energy when the power parameter level of the RF generator is not pulsed (e.g., operating in CW mode). Graph 904 plots the energy when the power parameter level is pulsed between multiple states using a power parameter pulsed RF generator. Note that when the power parameter level of a power parameter pulsed RF generator is pulsed between multiple states, the peak ion energy of plasma ions in the plasma within the plasma chamber 108 increases compared to the peak ion energy of plasma ions when using a CW mode RF generator. Furthermore, when the power parameter level of the power parameter pulsed RF generator is pulsed between multiple states, the angular distribution of plasma ions in the channel decreases compared to the angular distribution of plasma ions when a CW mode RF generator is used. It should also be noted that the amount of bias voltage supplied by the bias RF generator system 114 is the same (e.g., 300 volts) regardless of whether a power parameter pulsed RF generator or a CW mode RF generator is used. The increase in peak ion energy and decrease in angular distribution increase the etching rate of the substrate 122, and the bias voltage does not need to be increased to increase the etching rate. For example, the bias voltage of one or more RF signals generated and supplied by the bias RF generator system 114 is constant when the power parameter level of the power parameter pulsed RF generator is pulsed.

[0217] Figure 10 shows one embodiment of Graph 400.

[0218] Figure 11 shows one embodiment of Graph 1100 to illustrate that the same angular divergence achieved by increasing the bias voltage is achieved by pulsing the power parameter level of the power parameter pulsed RF generator. For the same bias voltage, the angular divergence is greater when the power parameter level of the RF generator connected to the upper electrode 106 operates in CW mode (e.g., not pulsed). The angular divergence is greater than that achieved using the power parameter pulsed RF generator. To increase the etching rate by achieving a smaller angular divergence, it is not necessary to increase the bias voltage when pulsing the power parameter level of the power parameter pulsed RF generator.

[0219] Figure 12 shows embodiments of Graph 1202A and Graph 1202B to illustrate the difference in the critical dimension of the channel formed within the substrate 122. Graph 1202A plots the channel height in nanometers compared to the channel width in nanometers. The critical dimension of the channel is shown as 21.9 nm in Graph 1202A. The critical dimension in Graph 1202A is achieved when a CW mode RF generator is used instead of a power parameter pulsed RF generator. Graph 1202B plots the channel height in substrate 122 in nanometers compared to the channel width in substrate 122 in nanometers. The critical dimension is shown as 19.2 nm in Graph 1202B. The lower critical dimension in Graph 1202B compared to Graph 1202A is achieved when the power parameter level of the power parameter pulsed RF generator is pulsed. A low critical dimension is achieved when the vertical orientation of plasma ions in the plasma chamber 108 is increased by a decrease in the angular divergence of plasma ions in the plasma chamber 108.

[0220] Figure 13A is a block diagram showing one embodiment of a plasma tool 1300 for achieving peak ion energy enhancement with low angular divergence. Plasma tool 1300 is the same as plasma tool 100 in Figure 1A, except that within plasma tool 1300, a bias RF generator RFGbs is used instead of the bias RF generator system 114. Unlike the bias RF generator system 114, which is a continuous-wave mode RF generator, the bias RF generator RFGbs is a multi-state RF generator. Plasma tool 1300 further comprises a host computer 116, an IMN 112, a plasma chamber 108, an RF generator RFGx (shown in Figure 1A), an RF generator RFGy (shown in Figure 1A), and an IMN 104 (shown in Figure 1A).

[0221] The RF generator RFGbs comprises a digital signal processor DSPbs, a power parameter controller PWRS1, another power parameter controller PWRS2, an automatic frequency adjuster AFTS, an RF power supply Pbs, and a driver system 1302. The digital signal processor DSPbs is connected to the power parameter controllers PWRS1 and PWRS2 and the automatic frequency adjuster AFTS. Furthermore, the power parameter controllers PWRS1 and PWRS2, as well as the automatic frequency adjuster AFTS, are connected to the driver system 1302. The driver system 1302 is connected to the RF power supply Pbs. The RF power supply Pbs is connected to the RF cable system 137 (to the RF cable of the RF cable system 137, etc.) via the output of the RF generator RFGbs.

[0222] The processor 132 accesses recipes from the memory device 134. Examples of recipes include power parameter setpoints applied to RF generator RFGbs during state S1, power parameter setpoints applied to RF generator RFGbs during state S2, and RF generator RFG during states S1 and S2. bs This includes the frequency setting points to which they apply, or a combination thereof.

[0223] The processor 132 transmits a command to the DSPbs along with the pulse signal 102 via the cable 117. The command transmitted to the DSPbs via the cable 117 includes information about the pulse signal 102, a power parameter setpoint applied to the RF generator RFGbs during state S1, a power parameter setpoint applied to the RF generator RFGbs during state S2, and a frequency setpoint applied to the RF generator RFGbs during states S1 and S2. The information about the pulse signal 102 indicates to the DSPbs that the RF signal generated by the RF generator RFGbs transitions from state S1 to state S2 at the transition time tst1 of the pulse signal 102, and that the RF signal transitions from state S2 to state S1 at the transition time tst2 of the pulse signal 102. DSPbs determines from the instruction that a power parameter setpoint for state S1 is applied during state S1 of the pulse signal 102, a power parameter setpoint for state S2 is applied during state S2 of the pulse signal 102, and frequency setpoints for states S1 and S2 are applied during states S1 and S2 of the pulse signal 102. Furthermore, DSPbs determines from the instruction and the pulse signal 102 that the RF signal generated by the RF generator RFGbs transitions from state S1 to state S2 at transition time tst1 of the pulse signal 102, and that the RF signal transitions from state S2 to state S1 at transition time tst2 of the pulse signal 102. Transition times tst1 and tst2 are repeated in each cycle of the pulse signal 102.

[0224] At the cycle transition time tst2 of pulse signal 102, DSPbs transmits the power parameter setpoint for state S1 to the power parameter controller PWRS1. Similarly, at the cycle transition time tst1 of pulse signal 102, DSPbs transmits the power parameter setpoint for state S2 to the power parameter controller PWRS2. Furthermore, at the cycle transition time tst2 or tst1 of pulse signal 102, DSPbs transmits the frequency setpoint for states S1 and S2 to the automatic frequency controller AFTS.

[0225] Upon receiving a power parameter setpoint for state S1, the power parameter controller PWRS1 determines the current amount corresponding to the power parameter setpoint for state S1. Based on the current amount generated by the driver system 1302 during state S1, the power parameter controller PWRS1 generates a command signal and transmits it to the driver system 1302. During state S1, in response to receiving the command signal, the driver system 1302 generates a current signal with the current amount and transmits it to the RF power supply Pbs. After receiving the current signal, the RF power supply Pbs generates an RF signal with the power parameter setpoint for state S1 and supplies this RF signal to the output of the RF generator RFGbs and to the input of the IMN 112 via the RF cable of the RF cable system 137. The power parameter setpoint for state S1 is maintained by the RF power supply Pbs of the RF generator RFGbs during state S1.

[0226] Similarly, upon receiving a power parameter setpoint for state S2, the power parameter controller PWRS2 determines the current amount corresponding to the power parameter setpoint for state S2. Based on the current amount generated by the driver system 1302 during state S2, the power parameter controller PWRS2 generates a command signal and transmits that command signal to the driver system 1302. During state S2, in response to receiving the command signal, the driver system 1302 generates a current signal having that current amount and controls the RF power supply Pbs The RF power supply Pbs, after receiving the current signal, generates an RF signal with a power parameter setpoint for state S2 and supplies that RF signal to the input of IMN 112 via the output of RF generator RFGbs and the RF cable of RF cable system 137. The power parameter setpoint for state S2 is maintained by the RF power supply Pbs of RF generator RFGbs during state S2.

[0227] Furthermore, upon receiving the frequency setpoints for states S1 and S2, the automatic frequency regulator AFTS determines the amount of current corresponding to the frequency setpoints for states S1 and S2. Based on the amount of current generated by the driver system 1302 during states S1 and S2, the automatic frequency regulator AFTS generates a command signal and transmits it to the driver system 1302. During states S1 and S2, in response to receiving the command signal, the driver system 1302 generates a current signal with the amount of current and transmits it to the RF power supply Pbs. After receiving the current signal, the RF power supply Pbs generates an RF signal with the frequency setpoints for states S1 and S2 and supplies that RF signal to the output of the RF generator RFGbs and to the input of the IMN 112 via the RF cable of the RF cable system 137. The frequency setpoints for states S1 and S2 are maintained by the RF power supply Pbs during states S1 and S2. The RF signal having a power parameter setpoint for state S1 and frequency setpoints for states S1 and S2 is the RF signal generated by the RF generator RFGbs during state S1. Similarly, the RF signal having a power parameter setpoint for state S2 and frequency setpoints for states S1 and S2 is the RF signal generated by the RF generator RFGbs during state S 2 Inside is the RF signal generated by the RF generator RFGbs.

[0228] The input to IMN112 receives the RF signal generated by the RF power supply Pbs from the output of the RF generator RFGbs via the RF cable of the RF cable system 137. The impedance of the load connected to the output of IMN112 is matched with the impedance of the source connected to the input of IMN112 to generate the output RF signal at the output of IMN112. Examples of sources connected to the input of IMN112 include the RF cable system 137 and the RF generator RFGbs. The output RF signal is transmitted to the chuck 110 (such as the lower electrode of the chuck 110) via the RF transmission line 139.

[0229] When one or more processing gases are supplied between the upper electrode 106 and the chuck 110, a modulated RF signal is supplied to the upper electrode 106, an output RF signal is supplied to the chuck 110, and one or more processing gases are ignited to generate or maintain plasma in the plasma chamber 108.

[0230] In various embodiments, the power parameter controllers PWRS1 and PWRS2, as well as the automatic frequency regulator AFTS, are modules (e.g., parts) of a computer program executed by DSPbs.

[0231] In some embodiments, the power parameter controllers PWRS1 and PWRS2, as well as the automatic frequency regulator AFTS, are separate integrated circuits connected to the integrated circuits of the DSPbs. For example, the power parameter controller PWRS1 is the first integrated circuit of the RF generator RFGbs, the power parameter controller PWRS2 is the second integrated circuit of the RF generator RFGbs, the automatic frequency regulator AFTS is the third integrated circuit of the RF generator RFGbs, and the DSPbs are the fourth integrated circuit of the RF generator RFGbs. Each of the first to third integrated circuits of the RF generator RFGbs is connected to the fourth integrated circuit of the RF generator RFGbs.

[0232] Figure 13B shows embodiments of Graphs 140, 1310, and 1312 to illustrate the pulsation of the power parameters of the RF signals generated by the RF generator RFGbs in Figure 13A. Graph 1310 plots the power parameter levels of the RF signals (e.g., RF signal 1314) generated by the RF generator RFGbs against time t. Furthermore, Graph 1312 plots the power parameter levels of the RF signals (e.g., RF signal 1316) generated by the RF generator RFGbs against time t.

[0233] Referring to Graphs 140 and 1310, in state S1, the RF signal 1314 has a power parameter level of "0" and a frequency level of "0". Furthermore, at transition time tst1, the RF signal 1314 transitions from state S1 to state S2. In state S2, the RF signal 1314 has a power parameter level of "Pb2" and a frequency level of "fb2". At transition time tst2, the RF signal 1314 transitions back from state S2 to state S1. The zero power parameter level of the RF signal 1314 prevents the plasma ions generated in state S1 from being directed towards the chuck 110. Thus, the plasma ions are saved to be utilized in state S2 to increase the vertical directionality of the plasma ions and further accelerate the etching rate.

[0234] Note that the duty cycle of RF signal 1314 in state S1 is the same as the duty cycle of RF signal 1314 in state S2. For example, the duty cycle of state S1 is 50%, and the duty cycle of state S2 is 50%. RF signal 1314 in state S1 accounts for 50% of the cycle of pulse signal 102, and RF signal 1314 in state S2 accounts for the remaining 50% of the cycle of pulse signal 102.

[0235] In various embodiments, the duty cycle of state S1 of the RF signal 1314 is different from the duty cycle of state S2 of the RF signal 1314. For example, the duty cycle of state S1 is 25%, and the duty cycle of state S2 is 75%. State S1 of the RF signal 1314 accounts for 25% of the cycles of the pulse signal 102, and state S2 of the RF signal 1314 accounts for the remaining 75% of the cycles of the pulse signal 102. As another example, the duty cycle of state S1 is a%, and the duty cycle of state S2 is (100-a)%. State S1 of the RF signal 1314 accounts for a% of the cycles of the pulse signal 102, and state S2 of the RF signal 1314 accounts for the remaining (100-a)% of the cycles of the pulse signal 102.

[0236] Note that the power parameter level "Pb2" and frequency level "fb2" are not zero, as shown in Graph 1310.

[0237] Graph 1312 is similar to Graph 1310, except that RF signals 1314 and 1316 have different power parameter levels in state S1. For example, RF signal 1314 has a power parameter level of "0" in state S1, and RF signal 1316 has a power parameter level of "Pb1" in state S1. Furthermore, RF signal 1316 has a frequency level of "fb1" in state S1, and the frequency level of "fb1" in state S1 is the same as the frequency level of RF signal 1316 "fb2" in state S2. RF signal 1316 has a power parameter level of "Pb2" in state S2. The lower power parameter level of RF signal 1316 in state S1 compared to state S2 prevents the plasma ions generated in state S1 from being directed towards the chuck 110 in state S1. Thus, the plasma ions are saved to be utilized in state S2 to increase the vertical directionality of the plasma ions and further accelerate the etching rate.

[0238] Referring to graphs 140 and 1312, state S2 of RF signal 1316 is the same as state S2 of RF signal 1314. For example, in state S2, RF signal 1316 has a power parameter level "Pb2", which is the same as the power parameter level "Pb2" of RF signal 1314 in state S2. Also, in state S2, RF signal 1316 has a frequency level "fb2", which is the same as the frequency level of RF signal 1314 in state S2.

[0239] Furthermore, at transition time tst1, RF signal 1316 transitions from state S1 to state S2. The power parameter level "Pb1" is higher than the power parameter level "0" of RF signal 1314 in state S1, but lower than the power parameter level "Pb2" of RF signal 1316 in state S2. At transition time tst2, RF signal 1316 transitions back from state S2 to state S1.

[0240] Note that the power parameter levels "Pb1" and "Pb2," as well as the frequency levels "fb1" and "fb2," are not zero, as shown in Graph 1312.

[0241] Note that the duty cycle of RF signal 1316 in state S1 is the same as the duty cycle of RF signal 1316 in state S2. For example, the duty cycle of RF signal 1316 in state S1 is 50%, and the duty cycle of RF signal 1316 in state S2 is 50%. RF signal 1316 in state S1 accounts for 50% of the cycle of pulse signal 102, and RF signal 1316 in state S2 accounts for the remaining 50% of the cycle of pulse signal 102.

[0242] In various embodiments, the duty cycle of RF signal 1316 in state S1 is different from the duty cycle of RF signal 1316 in state S2. For example, the duty cycle of RF signal 1316 in state S1 is 25%, and the duty cycle of RF signal 1316 in state S2 is 75%. RF signal 1316 in state S1 accounts for 25% of the cycles of pulse signal 102, and RF signal 1316 in state S2 accounts for the remaining 75% of the cycles of pulse signal 102. As another example, the duty cycle of RF signal 1316 in state S1 is a%, and the duty cycle of RF signal 1316 in state S2 is (100-a)%. RF signal 1316 in state S1 accounts for a% of the cycles of pulse signal 102, and RF signal 1316 in state S2 accounts for the remaining (100-a)% of the cycles of pulse signal 102.

[0243] In some embodiments, the frequency level "fb1" is different from (lower or higher than) the frequency level "fb2".

[0244] The embodiments described herein may be implemented in a variety of computer system configurations, including handheld hardware units, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, and mainframe computers. The embodiments may also be implemented in a distributed computing environment in which tasks are performed by remote processing hardware units connected over a network.

[0245] In some embodiments, the controller is part of the system, and the system may be part of the examples described above. Such a system comprises a semiconductor processing apparatus, including one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (such as a wafer pedestal, a gas flow system, etc.). These systems are integrated with electronic equipment for controlling the operation of the system before, during, and after processing of semiconductor wafers or substrates. The electronic equipment may also be called a “controller,” and can control various components or sub-components of one or more systems. Depending on the processing requirements and / or the type of system, the controller is programmed to control any of the processing disclosed herein, such as the supply of processing 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 rate settings, fluid supply settings, position and operation settings, and wafer movement in and out of a load lock connected to or coupled with tools and other moving tools and / or systems.

[0246] Generally, in various embodiments, a controller is defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. 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 that are communicated to the controller in the form of various individual settings (or program files) and define parameters, factors, variables, etc., to perform specific processing on or for semiconductor wafers or to the system. In some embodiments, program instructions are part of a recipe defined by a processing engineer to achieve one or more processing steps during the processing of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0247] In some embodiments, the controller is part of or connected to a computer, such computer is integrated with the system, connected to the system, networked with the system in other ways, or combined with the system. For example, the controller is in the “cloud” or is all or part of a fab host computer system that enables remote access to wafer processing. The computer enables remote access to the system to monitor the current progress of a manufacturing operation, examine the history of past manufacturing operations, or examine trends or performance indicators from multiple manufacturing operations, in order to change the parameters of the current operation, set up a processing step according to the current operation, or start a new operation.

[0248] In some embodiments, a remote computer (e.g., a server) provides processing recipes to the system via a network (including a local network or the Internet). The remote computer has a user interface that allows input or programming of parameters and / or settings, which are communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of data, which specify parameters, factors, and / or variables for each of the processing steps performed during one or more operations. It should be understood that the parameters, factors, and / or variables are specific to the type of processing to be performed and the type of tools that the controller is configured to interface with or control. Thus, as described above, the controller is distributed, for example, by comprising one or more separate controllers that are networked and operate toward a common purpose (such as the processing and control described herein). An example of a distributed controller for such a purpose includes one or more integrated circuits on a chamber that communicate with one or more integrated circuits located remotely (e.g., at the platform level or as part of a remote computer) that cooperate to control processing in the chamber.

[0249] Examples of systems to which the method is applied in various embodiments include, but are not limited to, plasma etching chambers or modules, deposition chambers or modules, spin rinse chambers or modules, metal plating chambers or modules, cleaning chambers or modules, bevel edge etching 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 etching (ALE) chambers or modules, ion implantation chambers or modules, track chambers or modules, and any other semiconductor processing systems that are related to or may be used in the processing and / or manufacturing of semiconductor wafers.

[0250] It should also be noted that in some embodiments, the above-described operation applies to several types of plasma chambers, such as inductively coupled plasma (ICP) reactors, transformer-coupled plasma chambers, plasma chambers with conductive tools, dielectric tools, and plasma chambers with electron cyclotron resonance (ECR) reactors. For example, one or more RF generators are connected to inductors within an ICP reactor. Examples of inductor shapes include solenoids, dome-shaped coils, and flat-shaped coils.

[0251] As described above, depending on the one or more processing steps performed by the tool, the host computer communicates with one or more of the following: other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, the main computer, another controller, or tool locations within the semiconductor manufacturing plant and / or tools used for material transport to or from load ports to carry containers of wafers.

[0252] With the embodiments described above in mind, it should be understood that some of the embodiments utilize various operations performed by a computer, including data stored in a computer system. These operations are operations that physically handle physical quantities. Any of the operations described herein that form part of these embodiments are useful mechanical operations.

[0253] Some embodiments further relate to hardware units or devices for performing these operations. The devices are specifically configured for dedicated computers. When defined as a dedicated computer, the computer can operate for a particular purpose while performing other processes, program executions, or routines not included in the particular purpose.

[0254] In some embodiments, the operation may be processed on a computer selectively activated or configured by one or more computer programs stored in computer memory, a cache, or retrieved via a computer network. Once data is retrieved via a computer network, that data may be processed by other computers on the computer network (e.g., a cloud of computing resources).

[0255] In one or more embodiments, the computer-readable code may be manufactured on a non-temporary computer-readable medium. The non-temporary computer-readable medium is any data storage hardware unit (e.g., a memory device) that stores data, which is then read by a computer system. Examples of non-temporary computer-readable media include hard drives, network-attached storage (NAS), ROM, RAM, compact disc-ROM (CD-ROM), CD-recordable (CD-R), CD-rewritable (CD-RW), magnetic tape, and other optical and non-optical data storage hardware units. In some embodiments, the non-temporary computer-readable medium includes a computer-readable tangible medium distributed across a network-attached computer system so that the computer-readable code is stored and executed in a distributed manner.

[0256] While the method operations described above are presented in a specific order, it should be understood that in various embodiments, other housekeeping processes may be performed between operations, or the method operations may be distributed to a system that allows for method operations to occur at slightly different times or at various intervals, or they may be arranged to be performed in a different order than described above.

[0257] Furthermore, in one embodiment, note that one or more features of any embodiment described herein may be combined with one or more features of any other embodiment without departing from the scope described in the various embodiments described in the present disclosure.

[0258] For better understanding, this embodiment has been described in some detail, but it is clear that some changes and modifications may be made within the scope of the appended claims. Therefore, this embodiment is regarded as illustrative and not restrictive, and the embodiment is not limited to the details shown herein. [Application Example 1] A method for operating a plasma chamber during etching to increase ion energy and reduce angular divergence of ions directed toward the substrate surface, A pulse signal is received to drive the operation of the plasma chamber, and the pulse signal has two states, including a first state and a second state. Operating the primary radio frequency (RF) generator at the primary frequency level during the first state, keeping the primary RF generator in the off state during the second state, and operating the primary RF generator during the first state generates an increased charge in the plasma sheath formed on the substrate, and the increased charge increases the thickness of the plasma sheath. Operating the secondary RF generator at a secondary frequency level during the second state, keeping the secondary RF generator in the off state during the first state, and operating the secondary RF generator during the second state utilizes at least a portion of the increased charge of the plasma sheath generated during the first state as additional power to enhance the ion energy generated during the second state, the additional power reduces the angular divergence of the ions when directed toward the surface of the substrate, the primary and secondary RF generators are connected to the upper electrode associated with the plasma chamber via an impedance matching circuit, In order to enhance the etching operation over multiple cycles of the first and second states, the primary and secondary RF generators are kept running in the first and second states in accordance with the pulse signal. A method that includes [a certain feature]. [Example 2] A method according to Example 1, wherein the primary RF generator operates to turn on during the first state for a predetermined period of time that is qualified to generate at least a threshold amount of charge for increasing the plasma sheath. [Example 3] A method according to Example 2, wherein the predetermined period is determined during a recipe calibration routine for etching a certain type of material on the surface of the substrate. [Example 4] A method relating to Example 2, wherein the predetermined period is in the range of 10% to 50% of the duty cycle of the pulse signal. [Application Example 5] A method according to Application Example 1, wherein the primary RF generator is a low-frequency RF generator, the secondary RF generator is a high-frequency RF generator, and the high-frequency RF generator has a higher operating frequency than the low-frequency RF generator. [Example 6] A method according to Example 1, wherein during the first state, the time constant associated with the plasma sheath increases, and at least a portion of the primary power level of the RF signal generated by the primary RF generator during the first state is added to the secondary power level of the RF signal generated by the secondary RF generator during the second state in order to enhance the etching operation during the second state. [Example 7] The method according to Example 1, further comprising operating the bias RF generator such that it has a first bias power parameter level during the first state and a second bias power parameter level during the second state, The first bias power parameter level is lower than the second bias power parameter level, the bias RF generator is connected to the chuck of the plasma chamber via another impedance matching circuit, and the first bias power parameter level of the bias RF generator assists the transition of ion energy formed in the first state to the second state, in this method. [Application Example 8] A method according to Application Example 1, wherein operating the primary RF generator at the primary frequency level during the first state increases the reactance of the plasma sheath, the increase in the reactance of the plasma sheath reduces the current through the plasma sheath accordingly, the decrease in the current increases the average resistance associated with the plasma sheath, the increase in the average resistance increases the average time constant associated with the plasma sheath and the first and second states, thereby extending the discharge time of the plasma sheath during the first and second states, the extension of the discharge time increases the peak ion energy of the ions and decreases the angular divergence of the ions. [Application Example 9] The method described in Application Example 1, further, It is determined that the primary RF generator operates at the primary power parameter level during the first state, During the first state, the primary RF generator is controlled to operate at the primary power parameter level, It is determined that the secondary RF generator operates at the secondary power parameter level during the second state, Controlling the secondary RF generator to operate at the secondary power parameter level during the second state, A method that includes [a certain feature]. [Example 10] A method according to Example 9, wherein the primary power parameter level is the same as the secondary power parameter level. [Example 11] A method according to Example 9, wherein the primary power parameter level is different from the secondary power parameter level. [Application Example 12] A method according to Application Example 1, wherein the upper electrode faces the chuck of the plasma chamber, the upper electrode is a transformer-coupled plasma coil, and the chuck is connected to a bias RF generator via another impedance matching circuit. [Application Example 13] A method according to Application Example 1, wherein the upper electrode faces the chuck of the plasma chamber, the upper electrode is a transformer-coupled plasma coil, and the chuck is connected to ground potential. [Application Example 14] A method for operating a plasma chamber during etching to increase ion energy and reduce angular divergence of ions directed toward the substrate surface, A pulse signal is received to drive the operation of the plasma chamber, and the pulse signal has two states, including a first state and a second state. Operating the primary radio frequency (RF) generator at a first primary frequency level during the first state and at a second primary frequency level during the second state, and operating the primary RF generator during the first state generates an increased charge in the plasma sheath formed on the substrate, and the increased charge increases the thickness of the plasma sheath. Operating the secondary RF generator at a first secondary frequency level during the first state and at a second secondary frequency level during the second state, and operating the secondary RF generator during the second state utilizes at least a portion of the increased charge of the plasma sheath generated during the first state as additional power to enhance the ion energy generated during the second state, the additional power reduces the angular divergence of the ions when directed toward the surface of the substrate, the primary and secondary RF generators are connected to upper electrodes associated with the plasma chamber via impedance matching circuits, and each of the first primary frequency level, second primary frequency level, first secondary frequency level, and second secondary frequency level is not zero, In order to enhance the etching operation over multiple cycles of the first and second states, the primary and secondary RF generators are kept running in the first and second states in accordance with the pulse signal. A method that includes [a certain feature]. [Example 15] A method according to Example 14, wherein the primary RF generator operates to turn on during the first state for a predetermined period of time that is qualified to generate a threshold amount of charge for increasing the plasma sheath. [Example 16] A method according to Example 15, wherein the predetermined period is determined during a recipe calibration routine for etching a certain type of material on the surface of the substrate. [Example 17] A method relating to Example 15, wherein the predetermined period is in the range of 10% to 50% of the duty cycle of the pulse signal. [Example 18] A method according to Example 14, wherein the primary RF generator is a low-frequency RF generator, the secondary RF generator is a high-frequency RF generator, and the high-frequency RF generator has a higher operating frequency than the low-frequency RF generator. [Example 19] A method according to Example 14, wherein during the first state, the time constant associated with the plasma sheath increases, and at least a portion of the primary power level of the RF signal generated by the primary RF generator during the first state is added to the secondary power level of the RF signal generated by the secondary RF generator during the second state in order to enhance the etching operation during the second state. [Example 20] The method according to Example 14, further comprising operating the bias RF generator such that it has a first bias power parameter level during the first state and a second bias power parameter level during the second state, The first bias power parameter level is lower than the second bias power parameter level, the bias RF generator is connected to the chuck of the plasma chamber via another impedance matching circuit, and the first bias power parameter level of the bias RF generator helps the transition of ion energy formed in the first state to the second state, in this method. [Example 21] A method according to Example 14, wherein operating the primary RF generator at the first primary frequency level during the first state increases the reactance of the plasma sheath, the increase in the reactance of the plasma sheath accordingly decreases the current through the plasma sheath, the decrease in the current increases the average resistance associated with the plasma sheath, the increase in the average resistance increases the average time constant associated with the plasma sheath and the first and second states, thereby extending the discharge time of the plasma sheath during the first and second states, the extension of the discharge time increases the peak ion energy of the ions and decreases the angular divergence of the ions. [Application Example 22] The method described in Application Example 14, further, The primary RF generator is determined to operate at a first primary power parameter level during the first state and at a second primary power parameter level during the second state. The primary RF generator is controlled to operate at the first primary power parameter level during the first state and at the second primary power parameter level during the second state. The secondary RF generator is determined to operate at a first secondary power parameter level during the first state and at a second secondary power parameter level during the second state. Controlling the secondary RF generator to operate at the first secondary power parameter level during the first state and at the second secondary power parameter level during the second state, A method that includes [a certain feature]. [Example 23] The method according to Example 22, wherein the first primary power parameter level, the second primary power level, the first secondary power parameter level, and the second secondary power level are the same. [Example 24] The method according to Example 22, wherein the first primary power parameter level and the second primary power level are different from the first secondary power parameter level and the second secondary power level. [Application Example 25] A method relating to Application Example 14, wherein the upper electrode faces the chuck of the plasma chamber, the upper electrode is a transformer-coupled plasma coil, and the chuck is connected to a bias RF generator via another impedance matching circuit. [Example 26] A method relating to Example 14, wherein the upper electrode faces the chuck of the plasma chamber, the upper electrode is a transformer-coupled plasma coil, and the chuck is connected to ground potential. [Application Example 27] A system for operating a plasma chamber to increase ion energy and reduce angular divergence of ions directed toward the substrate surface during etching, A primary radio frequency (RF) generator having a primary power supply configured to generate a primary RF signal, A secondary RF generator having a secondary power supply configured to generate a secondary RF signal, An impedance matching network connected to the primary power supply and the secondary power supply, configured to receive the primary RF signal and the secondary RF signal and generate a modulated RF signal, A plasma chamber having an upper electrode connected to the impedance matching network, wherein the plasma chamber is configured to receive the modulated RF signal, Equipped with, The primary RF generator is, A pulse signal is received to drive the operation of the plasma chamber, and the pulse signal has two states, including a first state and a second state. The system comprises one or more processors configured to operate the primary RF generator at a primary frequency level during the first state and to keep the primary RF generator in the off state during the second state, wherein the operation of the primary RF generator during the first state generates an increased charge in the plasma sheath formed on the substrate, and the increased charge increases the thickness of the plasma sheath, The aforementioned secondary RF generator is Upon receiving the aforementioned pulse, The system comprises one or more processors, which operate the secondary RF generator at a secondary frequency level during the second state and keep the secondary RF generator in the off state during the first state, wherein the operation of the secondary RF generator during the second state is configured to utilize at least a portion of the increased charge of the plasma sheath generated during the first state as additional power to enhance the ion energy generated during the second state, and the additional power reduces the angular divergence of the ions when directed toward the surface of the substrate. A system in which the primary and secondary RF generators are configured to continue operating in the first and second states in accordance with the pulse signal in order to enhance the etching operation over multiple cycles of the first and second states. [Example 28] A system according to Example 27, wherein the primary RF generator is configured to be turned on during the first state for a predetermined period of time that is qualified to generate a threshold amount of charge for increasing the plasma sheath. [Example 29] A system according to Example 28, wherein the predetermined period is determined during a recipe calibration routine for etching a certain type of material on the surface of the substrate. [Application Example 30] A system according to Application Example 28, wherein the predetermined period is in the range of 10% to 50% of the duty cycle of the pulse signal. [Application Example 31] A system according to Application Example 27, wherein the primary RF generator is a low-frequency RF generator, the secondary RF generator is a high-frequency RF generator, and the high-frequency RF generator has a higher operating frequency than the low-frequency RF generator. [Example 32] A system according to Example 27, wherein, in the first state, the time constant associated with the plasma sheath increases, the primary RF signal has a primary power level in the first state, and at least a portion of the primary power level is added to the secondary power level of the secondary RF signal in the second state to enhance the etching operation in the second state. [Application Example 33] The system described in Application Example 27, wherein the plasma chamber is equipped with a chuck, and the system further comprises A bias RF generator configured to have a first bias power parameter level in the first state and a second bias power parameter level in the second state, wherein the first bias power parameter level is lower than the second bias power parameter level. A system comprising an impedance matching circuit connected to the bias RF generator and the chuck of the plasma chamber, wherein the first bias power parameter level of the bias RF generator assists the transition of ion energy formed in the first state to the second state. [Application Example 34] A system according to Application Example 27, wherein the primary RF generator is configured to operate at the primary frequency level during the first state to increase the reactance of the plasma sheath, the increase in the reactance of the plasma sheath correspondingly reduces the current through the plasma sheath, the decrease in the current increases the average resistance associated with the plasma sheath, the increase in the average resistance increases the average time constant associated with the plasma sheath and the first and second states, thereby extending the discharge time of the plasma sheath during the first and second states, the extension of the discharge time increases the peak ion energy of the ions and decreases the angular divergence of the ions. [Application Example 35] The system described in Application Example 27, The primary RF generator is configured to operate at the primary power parameter level during the first state, The system is configured such that the secondary RF generator operates at the secondary power parameter level during the second state. [Application Example 36] A system according to Application Example 35, wherein the primary power parameter level is the same as the secondary power parameter level. [Application Example 37] A system according to Application Example 35, wherein the primary power parameter level is different from the secondary power parameter level. [Application Example 38] The system described in Application Example 27, wherein the plasma chamber comprises a chuck, the upper electrode faces the chuck, the upper electrode is a transformer-coupled plasma coil, and the system further comprises: A bias RF generator, An impedance matching circuit connected to the bias RF generator and the chuck, A system that includes these features. [Application Example 39] A system according to Application Example 27, wherein the plasma chamber comprises a chuck, the upper electrode faces the chuck, the upper electrode is a transformer-coupled plasma coil, and the chuck is connected to ground potential.

Claims

1. A method for pulsing a primary radio frequency (RF) signal and a secondary RF signal, The primary RF signal is supplied to the first impedance matching network connected to the upper electrode of the plasma chamber. The secondary RF signal is supplied to the first impedance matching network. The primary RF signal is pulsed between a first primary frequency level associated with the first state and a second primary frequency level associated with the second state, and the second primary frequency level differs from the first primary frequency level. A method comprising pulsing the secondary RF signal between a first secondary frequency level associated with the first state and a second secondary frequency level associated with the second state, wherein the second secondary frequency level is different from the first secondary frequency level.

2. The method according to claim 1, further, A method comprising supplying a bias RF signal to a second impedance matching network connected to the lower electrode of the plasma chamber, wherein the bias RF signal is a continuous wave signal.

3. The method according to claim 1, A method for pulsing the primary RF signal, comprising correcting the first primary frequency level of the primary RF signal to the second primary frequency level during a first transition time and correcting the second primary frequency level of the primary RF signal to the first primary frequency level during a second transition time, and for pulsing the secondary RF signal, comprising correcting the first secondary frequency level of the secondary RF signal to the second secondary frequency level during a first transition time and correcting the second secondary frequency level of the secondary RF signal to the first secondary frequency level during a second transition time.

4. The method according to claim 3, A method for pulsing the primary RF signal, comprising maintaining the first primary frequency level during a first state and maintaining the second primary frequency level during a second state, and for pulsing the secondary RF signal, comprising maintaining the first secondary frequency level during a first state and maintaining the second secondary frequency level during a second state.

5. The method according to claim 1, The method wherein the second primary frequency level is lower than the first primary frequency level.

6. The method according to claim 5, A method wherein the second secondary frequency level is higher than the first secondary frequency level.

7. The method according to claim 1, further, The primary RF signal is pulsed between a first primary power level associated with the first state and a second primary power level associated with the second state, and the second primary power level differs from the first primary power level. A method comprising pulsing the secondary RF signal between a first secondary power level associated with the first state and a second secondary power level associated with the second state, wherein the second secondary power level is different from the first secondary power level.

8. A system for pulsing primary radio frequency (RF) signals and secondary RF signals, A first RF generator having a first RF power supply configured to supply a primary RF signal to a first impedance matching network, wherein the first RF generator is configured to pulse the primary RF signal between a first primary frequency level associated with a first state and a second primary frequency level associated with a second state, and the first impedance matching network is configured to be connected to the upper electrode of a plasma chamber, and the second primary frequency level is different from the first primary frequency level. A system comprising: a second RF generator having a second RF power supply configured to supply a secondary RF signal to the first impedance matching network, the second RF generator configured to pulse the secondary RF signal between a first secondary frequency level associated with a first state and a second secondary frequency level associated with a second state, wherein the second secondary frequency level is different from the first secondary frequency level.

9. The system according to claim 8, further, A system comprising a third high-frequency generator having a third RF power supply configured to supply a bias RF signal to a second impedance matching network, wherein the second impedance matching network is configured to be connected to the lower electrode of the plasma chamber, and the bias RF signal is a continuous wave signal.

10. The system according to claim 8, A system in which, in order to pulse the primary RF signal, the first RF generator is configured to correct the first primary frequency level of the primary RF signal to the second primary frequency level during a first transition time and correct the second primary frequency level of the primary RF signal to the first primary frequency level during a second transition time, and in order to pulse the secondary RF signal, the second RF generator is configured to correct the first secondary frequency level of the secondary RF signal to the second secondary frequency level during a first transition time and correct the second secondary frequency level of the secondary RF signal to the first secondary frequency level during a second transition time.

11. The system according to claim 10, A system in which, in order to pulse the primary RF signal, the first RF generator is configured to maintain the first primary frequency level during a first state and the second primary frequency level during a second state, and in order to pulse the secondary RF signal, the second RF generator is configured to maintain the first secondary frequency level during a first state and the second secondary frequency level during a second state.

12. The system according to claim 8, A system in which the second primary frequency level is lower than the first primary frequency level.

13. The system according to claim 12, A system in which the second secondary frequency level is higher than the first secondary frequency level.

14. The system according to claim 8, The first RF generator is configured to pulse the primary RF signal between a first primary power level associated with the first state and a second primary power level associated with the second state, wherein the second primary power level differs from the first primary power level. The second RF generator is configured to pulse the secondary RF signal between a first secondary power level associated with the first state and a second secondary power level associated with the second state, wherein the second secondary power level is different from the first secondary power level.

15. A system for pulsing primary radio frequency (RF) signals and secondary RF signals, One or more primary controllers configured to control a primary RF power supply to generate the primary RF signal which is pulsed between a first primary frequency level associated with a first state and a second primary frequency level associated with a second state, wherein the second primary frequency level differs from the first primary frequency level. The system comprises one or more secondary controllers configured to control a secondary RF power supply to generate the secondary RF signal which is pulsed between a first secondary frequency level associated with the first state and a second secondary frequency level associated with the second state, wherein the second secondary frequency level differs from the first secondary frequency level. The primary RF power supply is configured to supply the primary RF signal to a first impedance matching network connected to the upper electrode of the plasma chamber. The system is configured such that the secondary RF power supply supplies the secondary RF signal to the first impedance matching network.

16. The system according to claim 15, further, A system comprising one or more bias controllers configured to control a bias RF power supply to generate a bias RF signal, wherein the bias RF signal is a continuous wave signal.

17. The system according to claim 15, A system in which, in order to pulse the primary RF signal, one or more primary RF controllers are configured to modify the first primary frequency level of the primary RF signal to the second primary frequency level during a first transition time and to modify the second primary frequency level of the primary RF signal to the first primary frequency level during a second transition time, and in order to pulse the secondary RF signal, one or more secondary RF controllers are configured to modify the first secondary frequency level of the secondary RF signal to the second secondary frequency level during a first transition time and to modify the second secondary frequency level of the secondary RF signal to the first secondary frequency level during a second transition time.

18. The system according to claim 15, The one or more primary controllers are configured to control the primary RF power supply to pulse the primary RF signal between a first primary power level associated with the first state and a second primary power level associated with the second state, wherein the second primary power level differs from the first primary power level. The one or more secondary controllers are configured to control the secondary RF power supply to pulse the secondary RF signal between a first secondary power level associated with a first state and a second secondary power level associated with a second state, wherein the second secondary power level is different from the first secondary power level.

19. The system according to claim 15, A system in which the second primary frequency level is lower than the first primary frequency level.

20. The system according to claim 19, A system in which the second secondary frequency level is higher than the first secondary frequency level.

21. A controller for pulsing primary radio frequency (RF) signals and secondary RF signals, It is a processor, The primary RF power supply is configured to control the primary RF power supply to generate the primary RF signal which is pulsed between a first primary frequency level associated with a first state and a second primary frequency level associated with a second state, wherein the second primary frequency level differs from the first primary frequency level. A processor configured to control a secondary RF power supply to generate the secondary RF signal pulsed between a first secondary frequency level associated with the first state and a second secondary frequency level associated with the second state, wherein the second secondary frequency level differs from the first secondary frequency level, the primary RF power supply is configured to supply the primary RF signal to a first impedance matching network connected to the upper electrode of the plasma chamber, and the secondary RF power supply is configured to supply the secondary RF signal to the first impedance matching network. A memory device connected to the aforementioned processor, A controller equipped with the following features.

22. A controller according to claim 21, The processor is configured to control a bias RF power supply to generate a bias RF signal, the bias RF signal being a continuous wave signal, and is a controller.

23. A controller according to claim 21, A controller configured such that, in order to pulse the primary RF signal, the processor corrects the first primary frequency level of the primary RF signal to the second primary frequency level during a first transition time, and corrects the second primary frequency level of the primary RF signal to the first primary frequency level during a second transition time, and in order to pulse the secondary RF signal, the processor corrects the first secondary frequency level of the secondary RF signal to the second secondary frequency level during a first transition time, and corrects the second secondary frequency level of the secondary RF signal to the first secondary frequency level during a second transition time.

24. A controller according to claim 21, The processor is configured to control the primary RF power supply to pulse the primary RF signal between a first primary power level associated with the first state and a second primary power level associated with the second state, wherein the second primary power level differs from the first primary power level. The processor is configured to control the secondary RF power supply to pulse the secondary RF signal between a first secondary power level associated with the first state and a second secondary power level associated with the second state, wherein the second secondary power level is different from the first secondary power level, and is a controller.

25. A controller according to claim 21, A controller in which the second primary frequency level is lower than the first primary frequency level.

26. A controller according to claim 25, A controller in which the second secondary frequency level is higher than the first secondary frequency level.

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