A radio wave generator that provides complex RF pulse patterns

Abstract

The radio frequency (RF) generator includes a pulse generation circuit configured to obtain an input signal indicative of a pulse pattern that defines an envelope of a pulsed RF signal. The pulse generation circuit stores data values ​​that define power levels and durations of segments of the pulse pattern. The pulse generator generates pulse modulation control signals in response to the stored data values, the pulse modulation control signals indicative of the power levels and durations of each segment of the pulse pattern, and the pulse modulation control signals are provided to a control circuit to generate control signals to adjust the amplitude and duration or width of the RF signal to generate a pulsed RF signal having the pulse pattern.

Description

Technical Field

[0001] The present invention relates to a radio frequency (RF) generator, and more particularly, to an RF generator that can generate a complex pulse pattern as an RF output signal using a simple circuit.

Background Art

[0002] A radio frequency (RF) generator or RF power supply is industrial equipment used to provide RF energy to a load device. RF generators are commonly used in the semiconductor industry, such as plasma semiconductor devices for generating plasma to manufacture silicon wafers. A typical RF system may include an RF generator and an impedance matching network that drives a load such as a plasma chamber. The RF power generated by the RF generator is precisely controlled to achieve desired process conditions. In semiconductor applications, the RF generator can generate a continuous wave (CW) signal or a pulse-modulated signal. The pulse-modulated RF generator applies an RF signal to the load by pulsing the RF signal.

[0003] More specifically, modern plasma semiconductor processes often use pulsed RF energy. Pulsed plasma (pulse plasma) provides higher etching rates, better uniformity, and less structural, electrical, or radiation (e.g., vacuum ultraviolet) damage. Pulse plasma can also improve unwanted artifacts in etched fine processed parts such as notches, bowing, microtrenching, and aspect ratio-dependent etching. Thus, pulse plasma can be essential for etching next-generation microdevices with feature sizes less than 10 nm.

[0004] The parsing requirements for an RF generator driving a plasma process have evolved from simple on / off output power parsing to a more complex level of parsing with multiple output levels having different timing requirements. The more complex these requirements become, the more complex circuitry is required to provide a pulse signal for modulating the RF power output. Current solutions for providing a pulse signal may involve using timing circuitry for each pulse power level, but in such implementations, there is a limit to the complexity of the RF pulse signal modulation that can be achieved. For example, in conventional solutions, when 3-level RF signal parsing is required, typically 4 to 6 timing circuits are needed to implement the pulse pattern. Conventional pulse timing control solutions are not practical when larger process control requirements are demanded for a large number of pulse levels such as 10 or 100.

Brief Description of the Drawings

[0005] Various embodiments of the present invention are disclosed in the following detailed description and the accompanying drawings.

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[0012] According to an embodiment of the present disclosure, a radio frequency (RF) generator incorporates a pulse generation circuit to generate a complex and arbitrary pulse modulation of an RF signal. In some embodiments, the pulse generation circuit includes a divide-by-N timer that communicates with a digital memory storage device that stores specifications for a desired pulse modulation at a set of memory locations. The pulse generation circuit generates a pulse modulation control signal that defines an envelope for the pulse-modulated RF output signal. The shape of the envelope of the pulse-modulated RF output signal can have a complex form as specified by the specifications stored in the digital memory storage device. Specifically, the pulse generation circuit of the present disclosure enables the RF generator to deliver a pulse-modulated RF output signal having an arbitrary pattern shape. Providing a complex pattern of RF power delivery leads to a new level of process control in RF-driven semiconductor devices.

[0013] The pulse generation circuit of the present disclosure enables the generation of a pulse-modulated RF signal with a high level of RF envelope complexity, which is a level of complexity that an RF generator cannot easily achieve while using conventional RF pulse generation methods. Specifically, the pulse generation circuit of the present disclosure does not require a large number of timing circuits. For example, conventional RF pulse generation methods often require one timing circuit for each desired pulse level. The pulse generation circuit of the present disclosure is simple to implement, provides higher flexibility and improved performance, and is cost-effective to construct compared to conventional RF pulse generation methods.

[0014] FIG. 1 is a schematic diagram of an RF system incorporating an RF generator in some embodiments. Referring to FIG. 1, RF system 1 is configured to supply an RF signal 8 for supplying RF power to a load 6. For example, the load 6 may be a semiconductor device such as a plasma semiconductor device. The RF signal 8 can be applied to generate plasma within a plasma tool, such as for etching semiconductor components. The RF system 1 includes an RF generator 2 that generates an RF signal 8 having a predetermined RF frequency. In some embodiments, the RF signal 8 can be a continuous wave, such as a sine wave, and the amplitude and / or frequency of the sine wave can be changed to vary the output power delivered to the load 6.

[0015] In other embodiments, the RF signal 8 can be a burst signal or a pulse-modulated RF signal, i.e., the RF signal is provided as a burst of sine wave signals of different pulse widths. As used herein, a pulse-modulated RF signal, also referred to as a "pulse RF signal," refers to a burst RF signal or a modulated RF signal. In other words, a pulse RF signal is an RF sine wave signal modulated by a pulse modulation control signal that defines the envelope of the modulated sine wave signal. In some embodiments, the RF sine wave signal is provided at a constant frequency and amplitude, but the power delivery to the load is changed by changing the pulse modulation control signal.

[0016] The RF signal 8 generated by the RF generator 2 is provided to the impedance matching network 4, which generates a matched RF signal 9 and provides it to the load 6. Specifically, the impedance matching network 4 operates to maximize the power provided to the load 6 and minimize the reflected power returned to the RF generator. The impedance matching network 4 attempts to adjust the input impedance of the matching network in order to match the characteristic impedance of the transmission line connecting the RF generator 2 to the matching network 4. As a result, the impedance matching network 4 modifies the RF signal 8, such as the phase of the RF signal, to generate the impedance-matched RF signal 9.

[0017] In this embodiment, the RF generator 2 obtains an input signal "RF power target" 7a that specifies the supplied RF power level(s). When the RF generator 2 provides a pulsed RF signal, the RF generator 2 may further obtain a second input signal "RF pulse target" 7B that specifies the pulse width or pulse duration of the pulsed RF signal. The RF generator 2 generates a pulsed RF signal 8 according to the power level and pulse width indicated by the RF power target 7A and the RF pulse target 7B. Further, the RF generator 2 performs RF signal level control by measuring or sampling the RF signal at its output terminal. Typically, the sampled RF signal 3, which includes the forward RF signal and the reflected RF signal, is fed back to the RF generator 2 to form a control loop for adjusting the level or amplitude of the RF signal. On the other hand, the impedance matching network 4 samples the pulsed RF signal 8, and the sampled RF signal 5 is used to adjust the input impedance of the matching network in order to match the characteristic impedance of the transmission line connecting the RF generator 2 to the matching network 4, as described above.

[0018] Embodiments of the present disclosure describe an RF generator incorporating a pulse generation circuit for controlling the pulse modulation of an output RF signal.

[0019] Figure 2 is a schematic diagram of an RF generator incorporating a pulse generation circuit according to an embodiment of the present disclosure. Referring to Figure 2, an RF generator 10 (also referred to as an "RF power supply") generates an RF signal from an RF signal source 22 and provides an RF signal for driving a load to an output terminal 36, usually via an impedance matching network. The RF generator 10 obtains an input signal RF power target (node 12) and an input signal RF pulse target (node 14) that specify a desired power level and a desired pulse width or pulse duration for which the RF signal is to be generated. In this embodiment, the generated RF signal is a pulse-modulated RF signal or a pulsed RF signal. In an embodiment of the present disclosure, the RF power target signal 12 can include one or more RF power setting values, and the RF pulse target signal 14 can include one or more pulse duration setting values.

[0020] The RF generator 10 includes a control device 40 that forms a feedback control loop within the RF generator to adjust the power level or amplitude of the RF signal. Specifically, the control device 40 generates a modulation control signal 49 for controlling the power level of the RF signal in response to the feedback control loop. The control device 40 further communicates with a pulse generation circuit 50 to generate the modulation control signal 49 and control the pulse envelope of the output RF signal to provide a desired pulse modulation pattern. As a result, the control device 40 generates an output RF signal (node 36) having an amplitude indicative of the RF power target (node 12) and a pulse envelope defined by the RF pulse target (node 14). The RF generator 10 may include other circuits and components (not shown) to assist in the function of the RF generator. Other circuits and components of the RF generator 10 are omitted in Figure 2 for simplicity of explanation.

[0021] More specifically, in the RF generator 10, the oscillator 22 functions as an RF signal source and provides an RF source signal at a predetermined RF frequency as the function of the RF clock CLK1. In one embodiment, the oscillator 22 generates an RF source signal that is a fixed amplitude sine wave at the RF frequency. The RF source signal is modulated by the signal modulator 26. In the embodiments of the present disclosure, the signal modulator 26 is configured to gate or modulate the RF source signal to generate a pulse-modulated RF signal as the output RF signal. The signal modulator 26 is connected to pulse-modulate the RF source signal in response to the modulation control signal 49 from the control device 40 and to adjust the signal level or amplitude of the RF source signal. The modulated RF signal generated by the signal modulator 26 may be amplified by the power amplifier 30 at a predetermined amplification factor. The power amplifier 30 amplifies the power of the RF signal to achieve the desired signal amplitude for the output RF signal. The RF signal generated in this way is provided to the output terminal 36 and can be transmitted to the load on the transmission line via the impedance matching network.

[0022] To implement feedback control, the RF signal is provided to output terminal 36 via directional coupler 31. Directional coupler 31 attenuates and extracts the respective forward RF power (node 33) and reflected RF power (node 35) at output terminal 36, and the sampled signal here is used in the feedback control loop to adjust the amplitude level of the output RF signal. In some embodiments, the directional coupler samples a small portion of the output power (forward RF signal or reflected RF signal) and routes the sample to control device 40. Control device 40 processes the forward and reflected RF signal samples to generate a measured signal level value. Next, control device 40 generates an error signal indicating the difference between the measured signal level value of the RF signal and a reference signal level. In some embodiments, the reference signal level is indicated by an RF power target (node 12) indicating the desired RF power level(s) for the output RF signal. Control device 40 generates a modulation control signal 49 in response to the error signal and controls the amplitude of the output RF signal via signal modulator 26. Configured in this way, a feedback control loop is formed within RF generator 10, enabling control device 40 to continuously monitor and control the output power level of the RF signal.

[0023] During operation, the control device 40 acquires a pulse modulation control signal 58 from the pulse generation circuit 50. The pulse generation circuit 50 acquires an RF power target (node 12) and an RF pulse target (node 14). The pulse generation circuit 50 generates a pulse modulation control signal 58 indicating a desired power level specified by the RF power target signal 12 and a desired pulse width specified by the RF pulse target signal 14. In one embodiment, the pulse modulation control signal 58 is a signal having a signal level indicating the desired power level and a signal pulse width indicating the desired pulse width. The pulse modulation control signal 58 is provided to the control device 40 as a reference signal level used to control or adjust the amplitude of the output RF signal within the feedback control loop. Further, the signal pulse width of the pulse modulation control signal 58 is provided to the control device 40 to indicate the duration for which pulse modulation is to be applied to the RF signal to generate the pulse-modulated RF signal. Specifically, the combination of the signal level and the signal pulse width of the pulse modulation control signal 58 specifies the shape or envelope of the pulse-modulated RF signal. In other embodiments, the pulse modulation control signal 58 can be provided as two signals, one of which indicates the power level and the other of which indicates the pulse duration. The exact structure of the pulse modulation control signal 58 is not critical to the practice of the present disclosure.

[0024] The control device 40 compares the forward RF power signal 33 with the pulse modulation control signal 58 to generate an error signal that drives the modulation control signal 49. As a result, the modulation control signal 49 drives the signal modulator 26 to correct the amplitude and control the modulation of the RF source signal 22 to generate an output RF signal having a desired signal amplitude (or RF power level) and a desired pulse modulation pattern. In some examples, the signal modulator 26 can be a multiplier that combines the RF source signal and the modulation control signal 49 provided by the control unit 40.

[0025] In this embodiment, the generated RF signal is a pulse - modulated RF signal. As used herein, a pulse - modulated RF signal, also referred to as a pulsed RF signal, means an RF signal of a predetermined RF frequency having an on - period during which the RF signal is provided to the output terminal and an off - period during which the RF signal is not provided. That is, the RF signal of the predetermined RF frequency is provided only during the on - period. The on - period and the off - period may be repeated, and the pulsed RF signal may have the same or different pulse widths for each pulse of the RF signal. Also, as used herein, the pulse - modulated RF signal may have various pulse patterns during the on - period in which the pulse pattern is specified by the RF power target signal 12 and the RF pulse target signal 14. For example, the pulse pattern may include two or more power levels, and each power level may have the same or different durations. The pulse generation circuit 50 in the RF generator 10 of the present disclosure is configured to generate a pulse - modulated RF signal having any desired modulation pattern for optimal RF power delivery to the load.

[0026] FIG. 3 is a schematic diagram of an RF generator incorporating a pulse generation circuit according to an embodiment of the present disclosure. Referring to FIG. 3, an RF generator 100 (also referred to as an “RF power supply”) includes an RF circuit 20, a control device 40, and a pulse generation circuit 50. The RF generator 100 generates an RF signal from an RF signal source 22 and provides the RF signal to an output terminal 36 for driving a load, usually via an impedance - matching network. The RF generator 100 may include other circuits and components (not shown) for assisting the function of the RF generator. Other circuits and components of the RF generator 100 are omitted in FIG. 3 for simplicity of explanation.

[0027] In the RF circuit 20, the oscillator 22 generates an RF source signal at a predetermined RF frequency as the function of the RF clock CLK1. In one embodiment, the oscillator 22 generates an RF source signal that is a fixed amplitude sine wave at the RF frequency. The RF source signal may be amplified by the driver 24. Next, the RF source signal is modulated by the signal modulator 26. The signal modulator 26 is configured to gate or modulate the RF source signal to generate a pulse-modulated RF signal as the output RF signal. The signal modulator 26 pulse-modulates the RF source signal in response to the modulation control signal 49 from the control device 40 and is connected to adjust the signal level or amplitude of the RF source signal. The modulated RF signal may be further amplified by the driver 28 and the power amplifier 30. For example, the power amplifier 30 amplifies the power of the RF signal output from the signal modulator 26 at a predetermined amplification rate. The power amplifier 30 amplifies the power of the RF signal to achieve the desired signal amplitude for the output RF signal. The RF signal generated in this way is provided to the output terminal 36 and can be transmitted to the load on the transmission line via the impedance matching network.

[0028] To implement feedback control, the RF signal is provided to the output terminal 36 of the RF circuit 20 via a pair 31 of directional couplers 32, 34. The directional couplers 32, 34 attenuate and extract the respective forward power (node 33) and reflected power (node 35) at the output terminal 36, where the sampled signal is used to monitor the output level of the RF generator 100. In other words, each directional coupler samples a small part of the output power (forward RF signal or reflected RF signal) and routes the sample to the control device 40.

[0029] In this embodiment, in the control device 40, the sample of the forward RF signal output by the directional coupler 32 is provided to an analog-to-digital converter (ADC) 42 and converted into a digital data sample. Similarly, the sample of the reflected RF signal output by the directional coupler 34 is provided to an analog-to-digital converter (ADC) 44 and converted into a digital data sample. The digital data samples of the forward RF signal and the reflected RF signal are processed by an error processor 45. The error processor 45 generates an error signal (node 46) indicating the difference between the measured signal level value of the RF signal as indicated by the digital data sample and the reference signal level. In the embodiments of the present disclosure, as will be described in more detail below, the reference signal level is indicated by a pulse modulation control signal 58 generated by a pulse generation circuit 50.

[0030] The control device 40 includes a control modulator 47 that combines the error signal 46 and the pulse modulation control signal 58 to generate a modulation control signal 49. In some embodiments, the modulation control signal 49 is a digital signal and is converted into an analog form by a digital-to-analog converter 48. The converted modulation control signal is then provided to the signal modulator 26 to control the modulation of the RF source signal 22 and to correct the level or amplitude of the RF source signal 22 to generate an output RF signal having a desired pulse modulation and a desired signal amplitude at the output terminal 36. Because of this configuration, a feedback control loop is formed within the RF generator 100, enabling the control device 40 to continuously monitor and control the output power or output level of the RF signal. The control device 40 generates a pulsed RF signal (node 36) having an amplitude indicating an RF power target (node 12) and a pulse envelope defined by an RF pulse target (node 14). In some embodiments, the signal modulator 26 is a multiplier that combines the RF source signal 22 and the modulation control signal 49 provided by the control device 40.

[0031] In this specification, the generated RF signal is a pulse - modulated RF signal. The pulse - modulated RF signal can have any pulse shape or pulse envelope as defined by an RF power target and an RF pulse target. The RF generator 100 includes a pulse generation circuit 50 that generates a pulse - modulation control signal 58 containing information on a desired signal level and a desired pulse duration for the pulse - modulated RF signal, and these desired signal level and desired pulse duration specify by combining the shape or envelope for the pulse - modulated RF signal.

[0032] In some embodiments, the pulse generation circuit 50 includes a digital memory 52 containing a series of memory locations, and each memory location stores the power level and pulse duration of a segment of the pulse RF signal to be generated. The pulse generation circuit 50 also includes a divide - N timer 54 that communicates with the digital memory 52 to generate a pulse - modulation control signal 58 for the control device 40. The logic circuit 56 controls the operation of the divide - N timer 54 and the digital memory 52.

[0033] In some embodiments, the digital memory 52 is an arrangement of random - access memory cells such as DRAM memory cells or SRAM memory cells. In some embodiments, the digital memory 52 includes a given number of memory locations to support programming of any pulse pattern for the pulse RF signal, including complex pulse patterns.

[0034] In some embodiments, the N-divider timer 54, also referred to as an N-divider clock or an N-divider counter, is a circuit for dividing a reference clock signal. For example, the N-divider timer 54 obtains a reference clock signal 53 having a clock frequency F = 1 / T, where T represents the clock period T of the reference clock signal. The N-divider timer 54 generates an output clock signal (also referred to as a "timing signal") that is reset by the Nth clock pulse of the reference clock signal. In this way, the N-divider timer is used to specify a given duration based on the frequency or clock period of the reference clock signal.

[0035] More specifically, the N-divider timer generates an output clock signal with a frequency that is the value of F divided by 2 N and a corresponding period that is the value of T multiplied by 2N. For example, when N = 1, the N-divider timer 54 generates an output clock signal with a frequency of 1 / 2T and a period of 2T. When N = 2, the N-divider timer 54 generates an output clock signal with a frequency of 1 / 4T and a period of 4T. In some embodiments, the N-divider timer 54 is implemented as one or more D flip-flops. In the case of two or more D flip-flops, the D flip-flops are connected in a serial chain.

[0036] In an embodiment of the present disclosure, the N-divider timer 54 and the digital memory 52 operate under the control of the logic circuit 56 to generate a pulse modulation control signal 58 in response to the RF power target 12 and the RF pulse target 14. Specifically, the RF power target signal 12 and the RF pulse target signal 14 provide set values that collectively specify the pulse pattern to be applied to the pulse-modulated RF signal. In this embodiment, each pulse pattern is divided into pulse segments (or "segments"), and each pulse segment is a part or interval of the pulse pattern having the same power level.

[0037] In the digital memory 52, each digital memory location stores data related to a pulse segment or pulse interval of a desired pulse pattern as programmed by the RF power target signal 12 and the RF pulse target signal 14. In some embodiments, each digital memory location stores two values for each pulse interval, namely, (1) the output power level of the pulse interval and (2) the duration of the pulse interval in time. The pulse generation circuit 50 sets the signal level of the pulse modulation control signal 58 using the power level number stored for each pulse interval. The signal level of the pulse modulation control signal 58 is provided to the control device 40 to adjust the power level of the RF signal within the feedback control loop. In this embodiment, the signal level of the pulse modulation control signal 58 is provided to the error processor 45 of the control device 40.

[0038] On the other hand, the N-divider timer 54 is given the number of interval durations stored for each pulse interval, and based on this number of interval durations, the N-divider timer 54 counts the clock pulses of the reference clock signal. In other words, the number of interval durations is used to set the Nth clock pulse of the reference clock signal 53, at which the interval duration ends and the output clock signal (or timing signal) of the N-divider timer 54 is reset. The timing signal of the N-divider timer 54 is used to set the pulse width or pulse duration of the pulse modulation control signal 58, which is used to control the pulse envelope of the RF signal. The pulse modulation control signal 58 thus generated includes a signal level indicating the desired power level and a signal pulse width indicating the desired pulse duration, and is provided to the control device 40.

[0039] During operation, when the timer reaches a programmed time interval indicating that a pulse segment has been completed, the digital memory 52 advances the digital memory position to the next pulse interval. The sequence continues until it reaches a memory position that includes an "end power level" or an "end duration value". The end power level or end duration value points the operation back to the start memory position. Since it is configured in this way, the pulse generator 50 can be programmed to generate pulse patterns of any level of complexity. The complexity of the pulse modulation pattern is limited only by the number of digital memory positions provided in the digital memory 52.

[0040] FIG. 4 includes FIGS. 4(a) and 4(b) and shows the configuration of the digital memory in the pulse generation circuit in an embodiment of the present disclosure. Referring to FIG. 4(a), the digital memory 52 in the pulse generation circuit 50 includes a series of digital memory positions 60a to 60n. In this embodiment, each memory position 60 stores a pair of values that specify the pulse interval or the power level and duration of the pulse segment of the pulse RF signal pattern. Specifically, the output power level (e.g., in watts) and duration (e.g., in microseconds) for a given pulse interval are stored in each memory position 60. The series of memory positions 60a to 60n stores a sequence of pulse intervals for defining a pulse pattern. The digital memory 52 starts at a start memory position such as 60a and operates by incrementing to each subsequent memory position until it reaches a memory position having an end power level or an end duration value. In this case, the digital memory 52 returns to the start memory position 60a and the sequence is repeated.

[0041] In one embodiment, a simple on-off pulse pattern requires programming three memory locations. In a first memory location, the value (500, 10) is stored for a pulse interval having a power level of 500 watts and a duration of 10 ms (on period). In a second memory location, the value (0, 90) is stored for a pulse interval having a power level of 0 watts and a duration of 90 ms (off period). In a third memory location, the value (-1, 0) is stored to indicate the end of the pulse sequence. In this example, a power level of "-1" indicates an end power level and a duration of "0" indicates an end duration value. The pulse RF signal specified by these three memory locations is as follows. The "on" power at the first memory location is 500 watts and persists for a duration of 10 ms. At the second memory location, an "off" power of 0 watts is held for 90 ms. When the third memory location is reached, the end of the pulse sequence is indicated and the memory pointer is immediately returned to the first memory location, and the process is repeated to generate the pulse pattern. The pulse pattern generated in this way has a repetition rate of 10 KHZ and a duty cycle of 10%.

[0042] Figure 4(b) shows another example of a pulse pattern that can be generated using the pulse generation circuit 50 in an embodiment of the present disclosure. Referring to Figure 4(b), the digital memory 52 includes several memory locations 60 that store pairs of data values that specify the power level and duration between pulses. At memory location 60-1, the values (500, 10) are stored. At memory location 60-2, the values (300, 40) are stored. At memory location 60-3, the values (0, 90) are stored. At memory location 60-4, the value (-1, 0) is stored to indicate the end of the pulse pattern sequence. The pulse RF signal specified by these four memory locations is as follows and is also shown in Figure 5(a). The "on" power at the first memory location is 500 watts and persists for a duration of 10 ms. The "on" power at the second memory location is 300 watts and persists for a duration of 40 ms. At the third memory location, an "off" power of 0 watts is held for 90 ms. When the fourth memory location is reached, the memory pointer is returned to the first memory location 60-1, and the pulse pattern is repeated by applying the values stored in each memory location in order from the first memory location 60-1 to the last memory location 60-4.

[0043] Figure 5, including Figures 5(a) and 5(b), includes exemplary pulse-modulated RF signal waveforms that can be generated by the pulse generation circuit of an RF generator in an embodiment of the present disclosure. Referring to Figure 5(a), the pulse-modulated RF signal 70 includes a pulse pattern having two different signal levels during the on period and different pulse durations. Specifically, the pulse-modulated RF signal 70 in Figure 5(a) is specified by the power and duration values stored in the digital memory 52 of Figure 4(b).

[0044] FIG. 5(b) shows another example of a complex pulse pattern of a pulsed RF signal that can be generated using the pulse generation circuit of the present disclosure. Referring to FIG. 5(b), the pulsed RF signal 72 includes a plurality of signal levels during the on-period, and each signal level has a different duration. The pulse pattern of FIG. 5(b) can be programmed using six memory locations in the digital memory of the pulse generation circuit.

[0045] The curves 70 and 72 of FIGS. 5(a) and 5(b) show the pulse envelopes of the pulse-modulated RF signals. During each on-period, the pulse-modulated RF signal has a predetermined RF frequency and provides an RF signal 75 having an amplitude defined by the pulse pattern. In this embodiment, the RF signal 75 is a sine wave form at the RF frequency. In the embodiments shown in FIGS. 5(a) and 5(b), the underlying sine wave form of the RF signal 75 is modulated by the pulse envelopes 72, 74 to generate the respective pulse-modulated RF signals.

[0046] The pulse generation circuit 50 of the present disclosure can advantageously be applied to generate complex pulse patterns for use as pulsed RF signals, thereby enabling improved process control. The simplicity and ease of implementation of the pulse generation circuit of the present disclosure cannot be achieved with conventional solutions.

[0047] FIG. 6 is a flowchart showing a method for generating a pulse-modulated RF signal in an RF generator according to an embodiment of the present disclosure. Referring to FIG. 6, a method 200 for generating a pulse-modulated RF signal (or pulsed RF signal) begins by generating an RF source signal of a first frequency (202). Next, the method 200 modulates the RF source signal in response to a control signal to generate a pulsed RF signal (204).

[0048] Method 200 obtains (206) an input signal indicative of a pulse pattern to be applied to a pulsed RF signal. Specifically, the pulse pattern defines the pulse envelope of the pulsed RF signal. In some embodiments, the input signal can be the RF power target signal and the RF pulse target signal described above. Method 200 stores (208) data values that describe the pulse pattern specified by the input signal in a series of memory locations. In some embodiments, each memory location stores data including the power level and duration value of each segment of the pulse pattern. The series of memory locations includes a last memory location that stores an end power level or an end duration value.

[0049] Method 200 selects (210) a first memory location from the series of memory locations. Method 200 reads (212) the power level and duration value from the selected memory location. Method 200 generates (214) a pulse modulation control signal having a signal level indicative of the read power level and a signal pulse width indicative of the read duration value. Method 200 provides (216) the signal level of the pulse modulation control signal as a reference signal level for controlling the amplitude of the pulsed RF signal and provides the signal pulse width of the pulse modulation control signal as a timing signal. The combination of the reference signal level and the timing signal defines the pulse envelope of the pulse-modulated RF signal. Method 200 generates (218) a control signal in response to the reference signal level and the timing signal. Method 200 modulates (220) the RF source signal in response to the control signal to generate a pulsed RF signal having the pulse pattern as the pulse envelope.

[0050] In some embodiments, when the timing signal indicates that the duration of each segment has ended, Method 200 moves to the next memory location and repeats the process until Method 200 reaches the last memory location having the end power level or the end duration value. In response to reaching the last memory location, Method 200 returns to the first memory location and the process repeats to generate a pulsed RF signal having the desired pulse pattern.

[0051] In embodiments of the present disclosure, the above-described pulse generation circuit 50 may be embodied as a device, system, method, or computer program product. Thus, aspects of the present disclosure, generally referred to herein as circuits, modules, components, or systems, may be embodied in any combination of software and hardware, including hardware, software (including firmware, resident software, microcode, etc.), or a computer program product embodied in a non-transitory computer-readable medium having computer-readable program code embodied thereon. In some embodiments, the pulse generation circuit 50 is implemented as a system including a hardware processor and a memory connected to the hardware processor, and the processor is configured to execute instructions stored in the memory to implement the function of generating a pulse modulation control signal in response to the RF power target signal and the RF pulse target signal as described above. The instructions may be program code, software code, or a software program that exists in firmware and / or on a computer-usable medium having control logic for enabling execution on the processor. For example, in some embodiments, the logic circuit 56 in the pulse generation circuit 50 may be a hardware processor that communicates with a memory storing program code or instructions, the N-divider timer 54 may be implemented in software or firmware stored in the memory, and the digital memory 52 may be implemented using an embedded memory in the hardware processor. The hardware processor in the pulse generation circuit 50 executes the program code or instructions stored in the memory to execute the operation of the N-divider timer and generate a pulse modulation control signal.

[0052] In this detailed description, various embodiments or examples of the present invention may be implemented in many ways, including a process, an apparatus, a system, a composition embodied on a non-transitory computer-readable storage medium, a computer program product, and / or a processor such as a hardware processor or a processor device configured to execute instructions stored on and / or provided by a memory connected to the processor, and / or a series of program instructions on a non-transitory computer-readable medium (e.g., a computer-readable storage medium or a computer network through which program instructions are sent via an optical communication link, an electronic communication link, or a wireless communication link). Generally, the order of the steps of the disclosed process may be changed within the scope of the present invention. Unless otherwise specified, components such as processors or memories described as being configured to perform tasks are implemented as general components temporarily configured to perform the tasks at a given time or as specific components manufactured to perform those tasks. As used herein, the term "processor" means one or more devices, circuits, and / or processing cores configured to process data such as computer program instructions.

[0053] A detailed description of one or more embodiments of the invention is provided above along with the accompanying drawings that illustrate the principles of the invention. The invention is described in relation to such embodiments, but the invention is not limited to any particular embodiment. Many modifications and variations are possible within the scope of the invention. The scope of the invention is limited only by the claims, and the invention encompasses numerous alternatives, modifications, and equivalents. To provide a complete understanding of the invention, many specific details are set forth in the specification. These details are provided for illustrative purposes and the invention may be practiced according to the claims without some or all of these specific details. For clarity, technical content known in the technical field related to the present invention is not described in detail so as not to unnecessarily obscure the invention. The invention is defined by the appended claims. The following items are the contents described in the claims of the international application. (Item 1) A radio wave generator, A radio frequency (RF) circuit comprising an RF signal source that provides an RF source signal of a first frequency and a signal modulator that generates a pulsed radio frequency (RF) signal, wherein the pulsed RF signal has an on period during which the RF signal is provided to an output terminal and an off period during which the RF signal is not provided, the radio frequency (RF) circuit; A control circuit configured to sample the pulsed RF signal at the output terminal and generate a control signal in response to at least the sampled pulsed RF signal to modulate the RF signal in the radio wave circuit; A pulse generation circuit configured to obtain an input signal indicating a pulse pattern that defines a pulse envelope of the pulsed RF signal, the pulse generation circuit storing data values that define a power level and a duration for a segment of the pulse pattern, the pulse generation circuit generating a pulse modulation control signal for each said segment in response to the stored data values, the pulse modulation control signal indicating the power level and the duration of each said segment of the pulse pattern, the pulse modulation control signal generating the control signal to adjust the amplitude and modulating the RF source signal to generate the pulsed RF signal having the pulse pattern as the pulse envelope, provided to the control circuit, the pulse generation circuit; A radio wave generator comprising. (Item 2) The radio wave generator according to item 1, wherein the control circuit provides the control signal to the signal modulator of the radio wave circuit to control the amplitude and modulation of the RF source signal to generate the pulsed RF signal. (Item 3) The pulse generation circuit, A digital memory having a plurality of memory locations, each memory location storing a power level and a duration value associated with a respective segment of the pulse pattern, and the last memory location storing an end power level or an end duration value, the digital memory; A frequency divider timer that receives the duration value of each segment from each memory location and generates a first signal indicating the duration value of each said segment; Comprising, The pulse generation circuit provides the power level stored from each memory location as the signal level of the pulse modulation control signal, and provides the first signal indicating the duration value stored at the same memory location as the pulse width of the pulse modulation control signal. The pulse modulation control signal is provided to the control circuit to generate the control signal, modulate the RF source signal, and generate the pulsed RF signal having the pulse envelope including each segment of the pulse pattern according to Item 1. (Item 4) The pulse generation circuit sequentially selects the memory locations in the digital memory from the first memory location to the last memory location. The pulse generation circuit generates the pulse modulation control signal using the duration value of each selected memory location and the power level of the same selected memory location. The pulse generation circuit returns to the first memory location in response to the selection of the last memory location, and is the radio wave generator according to Item 3. (Item 5) The N-divider timer counts the clock pulses of the reference clock signal based on the duration value, resets the pulse width of the pulse modulation control signal at the end of the duration value, and indicates the end of each segment, and is the radio wave generator according to Item 3. (Item 6) The pulse pattern includes two or more segments. Each segment includes a part of the pulse pattern having the same power level, and is the radio wave generator according to Item 1. (Item 7) The pulse pattern includes a plurality of segments. Each segment has a power level different from that of at least one other segment. Each segment has a duration different from that of at least one other segment, and is the radio wave generator according to Item 6. (Item 8) The control circuit further is configured with a first analog-to-digital converter and a second analog-to-digital converter that sample the respective forward RF signal and the reflected RF signal at the output terminal and generate digital samples of the respective forward RF signal and the reflected RF signal. An error processor configured to compare a measured signal level value with a reference signal level and generate an error signal indicating the difference, wherein the measured signal level is derived from the digital samples of the respective forward RF signal and the reflected RF signal, and the reference signal level is the power level indicated by the pulse modulation control signal provided by the pulse generation circuit, the error processor; A control modulation device configured to generate the control signal in response to the error signal and the pulse modulation control signal generated by the pulse generation circuit, wherein the pulse modulation control signal indicates the duration of each segment of the pulse pattern to be applied to the pulse RF signal, the control modulation device; The radio wave generator according to item 1, comprising: (Item 9) The radio wave generator according to item 1, further comprising a digital-to-analog converter configured to convert the control signal into an analog signal and connect the analog signal for controlling the signal modulator of the radio wave circuit. (Item 10) The radio wave generator according to item 1, wherein the digital memory comprises a plurality of randomly accessible memory cells. (Item 11) The radio wave generator according to item 3, wherein the N-divider timer comprises a plurality of D flip-flops connected in a series chain. (Item 12) The pulse generation circuit comprises a hardware processor and a memory coupled to the hardware processor, The memory is configured to provide instructions to the processor, and when the instructions are executed, the processor obtains the input signal indicating the pulse pattern defining the pulse envelope of the pulse RF signal, stores the data values defining the power level and duration of the segments of the pulse pattern, generates the pulse modulation control signal for each segment in response to the stored data values, wherein the pulse modulation control signal indicates the power level and the duration of each segment of the pulse pattern, the generating; To provide the pulse modulation control signal to the control circuit in order to generate the control signal, adjust the amplitude, modulate the RF source signal, and generate the pulse RF signal having the pulse pattern as the pulse envelope. The radio wave generator according to item 1, which executes the above. (Item 13) A method for generating a pulsed radio frequency (RF) signal in an RF generator, comprising: Generating an RF source signal of a first frequency; Modulating the RF source signal in response to a control signal to generate the pulse RF signal; Obtaining an input signal indicating a pulse pattern to be applied to the pulse RF signal, wherein the pulse pattern defines a pulse envelope of the pulse RF signal; Storing data values describing the pulse pattern specified by the input signal in a series of memory locations, each of the memory locations storing data including power level and duration values for respective segments of the pulse pattern, and the series of memory locations comprising a last memory location storing an end power level or an end duration value; Selecting a first memory location from the series of memory locations; Reading the power level and the duration value from the selected memory location; Generating a pulse modulation control signal having a signal level indicating the read power level and a signal pulse width indicating the read duration value; Providing the signal level of the pulse modulation control signal as a reference signal level for controlling the amplitude of the pulse RF signal; Providing the signal pulse width of the pulse modulation control signal as a timing signal; Generating the control signal in response to the reference signal level and the timing signal; Modulating the RF source signal in response to the control signal to generate the pulse RF signal having the pulse pattern as the pulse envelope; A method comprising the above. (Item 14) Selecting the memory locations in a series of memory locations from the first memory location to the last memory location. Repeating, for each selected memory location, reading the RF power level and the duration value to modulate the RF source signal and generate the pulsed RF signal having the pulse pattern as the pulse envelope; Responding to selection of the last memory location, returning to the first memory location and repeating selecting the memory location at the first memory location, the method according to item 13, further comprising. (Item 15) Modulating the RF source signal in response to the control signal comprises controlling the amplitude and width of the RF source signal by modulating the RF source signal in response to the control signal to generate the pulsed RF signal having the pulse pattern as the pulse envelope, the method according to item 13. (Item 16) Generating a pulse modulation control signal having a signal level indicating the read power level and a signal pulse width indicating the read duration value comprises generating the pulse modulation control signal having a signal pulse width indicating the duration value associated with a segment of the pulse pattern stored at the selected memory location using a N-divider timer, the method according to item 13. (Item 17) Using the N-divider timer to generate the pulse modulation control signal comprises Counting clock pulses of a reference clock signal based on the duration value; Resetting the timing signal at the end of the duration value to indicate the end of each segment, the method according to item 16. (Item 18) The pulse pattern comprises two or more segments; Each segment comprises a part of the pulse pattern having the same power level, the method according to item 13. (Item 19) The pulse pattern comprises a plurality of segments; Each segment has a power level different from at least one other segment; Each segment has a duration different from at least one other segment, the method according to item 18. (Item 20) Sampling a forward RF signal and a reflected RF signal related to the previous pulsed RF signal to generate digital samples of the forward RF signal and the reflected RF signal; Processing the selected digital samples to generate a measured signal level value; Determining an error signal indicative of a difference between the measured signal level value and the reference signal level; Generating the control signal in response to the error signal and the timing signal, wherein the timing signal indicates a duration of the segment of the pulse pattern to be applied to the pulsed RF signal; Applying the control signal to modulate the RF source signal to generate the pulsed RF signal having the pulse pattern, the method according to item 13 further comprising.

Claims

1. A radio wave generator, comprising a radio frequency (RF) circuit including an RF signal source that provides an RF source signal at a first frequency and a signal modulator that generates a pulsed radio frequency (RF) signal, the pulsed RF signal having an on period during which the RF signal is provided to an output terminal and an off period during which the RF signal is not provided, the radio frequency (RF) circuit; a control circuit configured to sample the pulsed RF signal at the output terminal and generate a control signal in response to at least the sampled pulsed RF signal to modulate the RF signal in the radio wave circuit; a pulse generation circuit configured to obtain an input signal indicating a pulse pattern that defines a pulse envelope of the pulsed RF signal, the pulse generation circuit storing data values that define power levels and durations for two or more respective segments of the pulse pattern, each segment being a portion of the pulse pattern having the same power level, the pulse generation circuit generating a pulse modulation control signal for each segment in response to the stored data values, the pulse modulation control signal indicating the power level and the duration of each segment of the pulse pattern, the pulse modulation control signal generating the control signal to adjust the amplitude and modulating the RF source signal to generate the pulsed RF signal having the pulse pattern as the pulse envelope, the pulse generation circuit being provided to the control circuit; A radio wave generator comprising the above.

2. The radio wave generator according to claim 1, wherein the control circuit provides the control signal to the signal modulator of the radio wave circuit to control the amplitude and modulation of the RF source signal to generate the pulsed RF signal.

3. The pulse generation circuit, A digital memory having a plurality of memory locations, each of said memory locations storing a power level and a duration value associated with a respective segment of said pulse pattern, and a last memory location storing an end power level or an end duration value, said digital memory; A divide-by-N timer that receives the duration value of each segment from each memory location and generates a first signal indicating the duration value of each segment; Comprising; The pulse generation circuit provides the power level stored from each memory location as the signal level of the pulse modulation control signal, and provides the first signal indicating the duration value stored in the same memory location as the pulse width of the pulse modulation control signal. The pulse modulation control signal generates the control signal and modulates the RF source signal to generate the pulse RF signal having the pulse envelope including each segment of the pulse pattern, and is provided to the control circuit. The radio wave generator according to claim 1.

4. The pulse generation circuit sequentially selects the memory locations in the digital memory from a first memory location to the last memory location. The pulse generation circuit generates the pulse modulation control signal using the duration value of each selected memory location and the power level of the same selected memory location. The pulse generation circuit returns to the first memory location in response to the selection of the last memory location. The radio wave generator according to claim 3.

5. The divide-by-N timer counts clock pulses of a reference clock signal based on the duration value and resets the pulse width of the pulse modulation control signal at the end of the duration value to indicate the end of each segment. The radio wave generator according to claim 3.

6. Each segment has a different power level from at least one other segment. The radio wave generator according to claim 1, wherein each of the segments has a duration different from that of at least one other segment.

7. The control circuit further a first analog-to-digital converter and a second analog-to-digital converter configured to sample respective forward RF signals and reflected RF signals at the output terminals and generate digital samples of the respective forward RF signals and reflected RF signals; an error processor configured to compare a measured signal level value with a reference signal level and generate an error signal indicating the difference, wherein the measured signal level is derived from the digital samples of the respective forward RF signals and reflected RF signals, and the reference signal level is the power level indicated by the pulse modulation control signal provided by the pulse generation circuit; the error processor; a control modulation device configured to generate the control signal in response to the error signal and the pulse modulation control signal generated by the pulse generation circuit, wherein the pulse modulation control signal indicates the duration of each segment of the pulse pattern to be applied to the pulse RF signal; the control modulation device; The radio wave generator according to claim 1, comprising

8. The radio wave generator according to claim 1, further comprising a digital-to-analog converter configured to convert the control signal into an analog signal and connect the analog signal for controlling the signal modulator of the radio wave circuit.

9. The radio wave generator according to claim 3, wherein the digital memory comprises a plurality of randomly accessible memory cells.

10. The radio wave generator according to claim 3, wherein the N-divider timer comprises a plurality of D flip-flops connected in a series chain.

11. The pulse generation circuit includes a hardware processor and a memory coupled to the hardware processor, The memory is configured to provide instructions to the processor, and when the instructions are executed, the processor acquires the input signal indicating the pulse pattern that defines the pulse envelope of the pulse RF signal, stores the data values that define the power level and duration of each segment of the pulse pattern, generates the pulse modulation control signal for each segment in response to the stored data values, the pulse modulation control signal indicating the power level and the duration of each segment of the pulse pattern, the generating provides the pulse modulation control signal to the control circuit to generate the control signal to adjust the amplitude and modulate the RF source signal to generate the pulse RF signal having the pulse pattern as the pulse envelope, The radio wave generator according to claim 1, which causes the above to be executed.

12. A method of generating a pulsed radio frequency (RF) signal in an RF generator, comprising: generating an RF source signal of a first frequency; modulating the RF source signal in response to a control signal to generate the pulse RF signal; acquiring an input signal indicating a pulse pattern to be applied to the pulse RF signal, the pulse pattern defining a pulse envelope of the pulse RF signal, the acquiring Storing data values that describe the pulse pattern specified by the input signal in a series of memory locations, each of the memory locations storing data including power levels and duration values for two or more respective segments of the pulse pattern, each of the segments being a part of the pulse pattern having the same power level, the series of memory locations comprising a last memory location that stores an end power level or an end duration value, the storing; Selecting a first memory location from the series of memory locations; Reading the power level and the duration value from the selected memory location; Generating a pulse modulation control signal for each segment having a signal level indicating the read power level and a signal pulse width indicating the read duration value; Providing the signal level of the pulse modulation control signal as a reference signal level for controlling the amplitude of the pulse RF signal; Providing the signal pulse width of the pulse modulation control signal as a timing signal; Generating the control signal in response to the reference signal level and the timing signal; Modulating the RF source signal in response to the control signal to generate the pulse RF signal having the pulse pattern as the pulse envelope; A method comprising.

13. Selecting the memory locations at a series of memory locations from the first memory location to the last memory location; Repeating reading the power level and the duration value for each selected memory location to modulate the RF source signal and generate the pulse RF signal having the pulse pattern as the pulse envelope; Responding to the selection of the last memory location, returning to the first memory location and repeating selecting the memory location at the first memory location, the method according to claim 12, further comprising.

14. Modulating the RF source signal in response to the control signal comprises modulating the RF source signal in response to the control signal to control the amplitude and width of the RF source signal in order to generate the pulsed RF signal having the pulse pattern as the pulse envelope, the method according to claim 12.

15. Generating a pulse modulation control signal for each segment having a signal level indicating the read power level and a signal pulse width indicating the read duration value comprises generating, using an N-divider timer, the pulse modulation control signal having a signal pulse width indicating the duration value associated with each segment of the pulse pattern stored in the selected memory location, the method according to claim 12.

16. Generating the pulse modulation control signal using the N-divider timer comprises counting clock pulses of a reference clock signal based on the duration value and resetting the timing signal at the end of the duration value to indicate the end of each segment, the method according to claim 15.

17. Each segment has a power level different from at least one other segment, and each segment has a duration different from at least one other segment, the method according to claim 12.

18. Sampling a forward RF signal and a reflected RF signal associated with the previous pulsed RF signal to generate digital samples of the forward RF signal and the reflected RF signal, processing the selected digital samples to generate a measured signal level value, determining an error signal indicating a difference between the measured signal level value and the reference signal level, Generating the control signal in response to the error signal and the timing signal, wherein the timing signal indicates the duration of each segment of the pulse pattern to be applied to the pulsed RF signal, and the generating; The method according to claim 12, further comprising modulating the RF source signal by applying the control signal to generate the pulsed RF signal having the pulse pattern.

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