Real-time measurement of microwave resonators as plasma diagnostics for process monitoring

Abstract

The embodiments disclosed herein include an apparatus comprising a board having a signal generator for generating chirp signals on the board. In an embodiment, a first mixer is on the board and is electrically coupled to the signal generator, and a circulator is on the board. In an embodiment, the circulator includes a first port electrically coupled to the mixer, a second port electrically coupled to a connector, and a third port. In an embodiment, a second mixer is on the board and is electrically coupled to the third port of the circulator. In an embodiment, an analog-to-digital converter (ADC) is on the board and is electrically coupled to the second mixer.

Description

Technology Field

[0001] Cross-reference of related applications

[0002] This application claims priority to U.S. Patent Application No. 18 / 401,112 filed December 29, 2023, the entire contents of which are incorporated herein by reference.

[0003] field

[0004] The embodiments relate to the field of semiconductor manufacturing, and in particular, to real-time measurement of microwave resonators for plasma diagnosis. Background Technology

[0005] Semiconductor processing environments often utilize plasma sources. To provide highly repeatable and stable processing environments, it is desirable to measure various plasma properties, such as electron density, electron temperature, and similar parameters. In some cases, high-density plasmas are used. High-density plasmas are particularly difficult to measure with conventional measurement tools.

[0006] One limitation of existing tools is that providing real-time measurements of plasmas is inherently difficult. Without the ability to capture real-time information regarding plasma conditions, the necessary control of process parameters cannot be accurately maintained. In such cases, applications such as chamber alignment are also limited. Furthermore, current solutions can be relatively invasive to the processing environment, making them unsuitable for high-volume manufacturing (HVM).

[0007] The embodiments disclosed herein include an apparatus comprising a board having a signal generator for generating chirped signals on the board. In an embodiment, a first mixer is on the board and is electrically coupled to the signal generator, and a circulator is on the board. In an embodiment, the circulator includes a first port electrically coupled to the mixer, a second port electrically coupled to a connector, and a third port. In an embodiment, a second mixer is on the board and is electrically coupled to the third port of the circulator. In an embodiment, an analog-to-digital converter (ADC) is on the board and is electrically coupled to the second mixer.

[0008] The embodiments disclosed herein may also include a method for monitoring plasma properties in real time. In an embodiment, the method includes the step of generating a chirp signal having a first frequency range and the step of converting the first frequency range to a second frequency range higher than the first frequency range. In an embodiment, the method further includes the step of providing the chirp signal to a resonator for interaction with the plasma, wherein the plasma-modified resonant frequency of the resonator is measured by the reflected chirp carrier signal. In an embodiment, the process further includes converting the reflected signal to a third frequency range lower than the second frequency range. In an embodiment, the method further includes the step of extracting plasma properties from the reflected signal.

[0009] The embodiments disclosed herein further comprise a tool. In an embodiment, the tool comprises a chamber suitable for generating plasma. In an embodiment, the tool further comprises a pedestal within the chamber to support a substrate, and a sensor at least partially within the chamber to measure plasma properties. In an embodiment, the sensor comprises a resonator or a transmission line, and an RF circuit coupled to the resonator. In an embodiment, the RF circuit is configured to generate chirp pulses supplied to the resonator. Brief explanation of the drawing

[0010] FIG. 1a is a schematic diagram of a device including an RF circuit for generating chirp pulses that are up-converted and down-converted for use in measuring plasma properties, according to an embodiment. FIG. 1b is a schematic diagram of a device including an RF circuit for generating chirped pulses that are down-converted for use in measuring plasma properties, according to an embodiment. FIG. 1c is a schematic diagram of a device including an RF circuit for generating chirp pulses including a digital domain for parts of the device, according to an embodiment. FIG. 2 is a sequential diagram of chirp pulses when the chirp pulses are up-converted and down-converted for use in measuring plasma properties according to an embodiment. FIG. 3 is a plot of a plurality of chirp pulses generated over a time duration according to an embodiment. FIG. 4a is a schematic diagram of an RF circuit section for a real-time plasma sensor according to an embodiment. FIG. 4b is a schematic diagram of an RF circuit section for a real-time plasma sensor according to an additional embodiment. FIG. 5a is a cross-sectional view of a tool including a plasma chamber and a real-time plasma sensor provided on the wall of the plasma chamber, according to an embodiment. FIG. 5b is a cross-sectional view of a tool according to an embodiment, comprising a plasma chamber and a real-time plasma sensor provided on a probe extending from the wall of the plasma chamber. FIG. 6 is a plan view of a real-time plasma sensor integrated into a substrate that can be placed in a plasma chamber according to an embodiment. FIG. 7 is a process flowchart of a process for measuring plasma properties in real time with a chirped pulse signal according to an embodiment. FIG. 8 is a process flowchart of a process for measuring plasma properties in real time with a chirped pulse signal according to an additional embodiment. FIG. 9 illustrates a block diagram of an exemplary computer system that can be used with a processing tool according to an embodiment. Specific details for implementing the invention

[0011] The systems described herein include systems for providing real-time measurements of plasma properties using chirped pulse carrier signals. In the following description, many specific details are provided to provide a thorough understanding of the embodiments. It will be apparent to those skilled in the art that the embodiments may be practiced without these specific details. In other cases, well-known aspects are not described in detail so as not to unnecessarily obscure the embodiments. Furthermore, it should be understood that the various embodiments depicted in the accompanying drawings are exemplary representations and are not necessarily drawn to actual scale.

[0012] As mentioned above, plasma diagnostics are limited by several factors. One prominent limiting factor is that real-time monitoring of plasma behavior is not possible with existing sensor solutions, particularly when considering implementation in High Volume Manufacturing (HVM) environments. Currently, boxcar averaging methods are used to obtain time-resolved measurements. However, these approaches require a triggering signal and are inherently delayed; that is, they do not approach "real-time" capabilities. Boxcar solutions can require time durations of approximately 0.1 to 1 second or more. This is particularly problematic when the plasma is pulsed or undergoes other rapid changes.

[0013] As used herein, “real-time” monitoring may refer to monitoring the properties of plasma (or other forms of matter) with a minimum delay between the detection of a signal and the output of a measurement. More specifically, “real-time” may refer to a measurement process in which the delay between the detection of a signal and the output of a measurement is approximately 10 μs or less, approximately 5.0 μs or less, approximately 1.0 μs or less, or approximately 0.1 μs or less. The real-time sensing provided by the embodiments disclosed herein allows for improvements in time resolution of three orders of magnitude or more compared to existing solutions. As used herein, “approximately” may refer to a value within 10 percent of the mentioned value. For example, approximately 10 μs may refer to a range of 9.0 μs to 11 μs.

[0014] The embodiments disclosed herein may provide real-time detection through the use of electronic circuits and systems that rely on pulsed chirp signals. The chirp signal may measure a large bandwidth within short time periods (e.g., 10 μs or less). For example, the bandwidth of the chirp may be up to approximately 1 GHz or up to approximately 5 GHz. Thus, a wide spectrum may be detected in a single pulse cycle to allow for real-time analysis.

[0015] In an embodiment, the sensing system may include a resonator exposed to a plasma environment. For the resonator, a shift in the resonant frequency of the resonator when exposed to plasma (as opposed to vacuum) may be used to measure one or more plasma properties. The resonator may be coupled to an electrical circuit configured to generate chirps and process the resulting signals. While resonator-based plasma monitoring techniques may be used in some embodiments, other applications for chirp pulse methods may utilize non-resonator type plasma diagnostic implementations. For example, cutoff probe techniques including electrically conductive transmission lines may be used in place of the resonator component. In the case of a cutoff probe, the transmission line may measure the frequency of the plasma to calculate one or more plasma properties. In an embodiment, the electrical circuit may include a chirp generator. This allows for rapid monitoring of microwave resonances that can be used as plasma diagnostics. After the chirp pulse is generated, some additional circuitry (e.g., RF circuitry) may be used to transform the chirp pulse to a suitable carrier frequency. After interacting with the resonator, the reflected chirp pulse is down-converted and sampled. These circuit components can be integrated onto a board such as a motherboard, a printed circuit board (PCB), or a similar board.

[0016] The sensor (including the circuit and resonator) can be integrated into the processing tool via various approaches depending on the needs of the device. In one case, the sensor may be a wall-mounted component on the inner surface of a plasma chamber. This embodiment may be suitable for HVM tools. Other embodiments may involve mounting the resonator on a probe extending toward the center of the chamber. These embodiments may be more suitable for diagnostic or research and development purposes. In yet another embodiment, the sensor may be integrated as a diagnostic wafer (or substrate) that can be transferred between tools.

[0017] The embodiments disclosed herein may allow for improved process monitoring of plasma conditions and environments. Chamber fingerprinting may also be implemented. Thus, improved control of a given process may be implemented to improve process uniformity and other metrics. Additionally, chamber matching processes may be used when multiple chambers are monitored by sensors. Furthermore, the real-time nature of process monitoring allows pulsed plasma conditions to be accurately monitored and controlled.

[0018] Now, referring to FIG. 1a, a schematic diagram of a sensor (100) according to an embodiment is shown. In an embodiment, the sensor (100) may include a resonator (120) coupled to an associated circuit. In an embodiment, the circuit may include an RF circuit. Components described as being "electrically coupled" to each other as used herein are components connected to each other by an electrical circuit or similar. In some embodiments, the components may be directly connected to each other such that a trace has a first end in the first component and a second end in the second component. In other embodiments, the electrically coupled components may have one or more interposed components. For example, the first component may be electrically coupled to the second component, and a third component is provided along an electrical path between the first component and the second component.

[0019] In an embodiment, the electrical circuit may include a signal generator (110). To provide real-time measurements, the signal generator (110) may include a function for generating a chirp signal. In an embodiment, the signal generator (110) may generate a signal at constant power by forming a time-varying frequency at a variable frequency ramp generation time. The chirp signal may have a pulse length of approximately 10 μs or less, approximately 5.0 μs or less, approximately 1.0 μs or less, or approximately 0.1 μs or less. The bandwidth of the chirp may be up to 1.0 GHz, up to 2.0 GHz, or up to 5.0 GHz. For example, in some embodiments, the frequency range of the chirp pulse may be from 0.01 GHz to 1.0 GHz. In an embodiment, the signal generator (110) may include a direct digital synthesizer (DDS).

[0020] In an embodiment, the signal generator (110) may be electrically coupled to the first mixer (112). In an embodiment, a digital-to-analog converter (DAC) (107) and a band-pass filter (BPF) (106) may be provided between the signal generator (110) and the first mixer (112). This allows the signal generator (110) to generate a digital signal that is converted into an analog signal for use in measuring the properties of the plasma. Additionally, in some embodiments, a high-pass filter (HPF) (not shown) may be provided after the first mixer (112). The first mixer (112) may include an RF port (117) for receiving the chirp signal. In an embodiment, the first mixer (112) is configured to upconvert the chirp pulse to a suitable carrier frequency for subsequent use by the resonator (120). For example, the chirp pulse may have a first frequency range that is converted to a second frequency range by the first mixer (112). The second frequency range may be higher than the first frequency range. For example, when the first frequency range is 0.01 GHz to 1.0 GHz, the second frequency range may be 9.01 GHz to 10 GHz.

[0021] In an embodiment, the first mixer (112) may be electrically coupled to the circulator (114). The circulator (114) may have three ports (121, 122, and 123). The first port (121) may be electrically coupled to the mixer (112). Thus, the modified chirp pulse is transmitted to the first port (121). Subsequently, the circulator (114) propagates the modified chirp pulse to the second port (122). The modified chirp pulse is propagated to a resonator (120) electrically coupled to the second port (122) of the circulator (114).

[0022] In an embodiment, the resonator (120) may be exposed to a plasma environment. For example, the resonator (120) may be located along the sidewall of a plasma chamber (not shown), on a probe within the plasma chamber, or on a wafer inserted into the plasma chamber. The resonator (120) may have any suitable architecture to interact with the plasma. In a specific embodiment, the resonator (120) may be a half-wave probe resonator or other microwave resonator (120) structure. The resonator (120) interacts with the plasma so that the resonant frequency is detected by a chirp pulse after being dielectrically modified.

[0023] In an embodiment, the reflected signal from the resonator (120) is transmitted back to the circulator (114), and the circulator (114) routes the reflected signal to the third port (123). In an embodiment, the circulator (114) is electrically coupled to the second mixer (116). For example, the third port (123) is electrically coupled to the RF port (117) of the second mixer (116). In an embodiment, the second mixer (116) downconverts the chirp pulse to a frequency range more suitable for sampling. For example, the frequency range may be converted back to the original frequency range generated by the signal generator (110). However, in other embodiments, the frequency range may be any frequency range below the frequency range of the chirp pulse after the first mixer (112).

[0024] In an embodiment, the first mixer (112) may be electrically coupled to the second mixer (116). For example, a phase-locked loop (PLL) synthesizer (115) may be provided between the first mixer (112) and the second mixer (116). The PLL synthesizer (115) may be coupled to a first local oscillator (LO) (111) in the first mixer (112) and a second LO (113) in the second mixer (116). The PLL synthesizer (115) may allow both of these mixers to be phase-locked to allow for improved signal distortion in the first mixer (112) and the second mixer (116) and to allow for improved measurement accuracy during frequency recovery.

[0025] In an embodiment, the second mixer (116) may be electrically coupled to the sampling component (118). The sampling component (118) may be used to extract the frequency of the plasma from the chirp pulse carrier signal. In an embodiment, the sampling component (118) may include an analog-to-digital converter (ADC). Subsequently, the extracted resonant frequency may be used to determine one or more plasma properties. For example, plasma electron density, electron temperature, or something similar may be determined by analyzing the resonant frequency. In an embodiment, an LPF (119) may be provided between the second mixer (116) and the sampling component (118) to improve the quality of the signal provided to the sampling component (118).

[0026] Now, referring to FIG. 1b, a schematic diagram of a sensor (101) according to an additional embodiment is shown. In an embodiment, the sensor (101) may include a resonator (120) electrically coupled to a circuit. For example, the circuit may be an RF circuit. In an embodiment, the circuit may be provided on a board such as a motherboard, a PCB, or something similar.

[0027] In an embodiment, the electrical circuit may include a signal generator (110). The signal generator (110) of FIG. 1b may be similar to the signal generator (110) of FIG. 1a except for the frequency range. Instead of providing a low frequency range (e.g., having an upper frequency of about 1.0 GHz or about 2.0 GHz), the frequency range may have an upper frequency of approximately 5 GHz or 10 GHz or higher. For example, the frequency range of the chirp pulse may be 9.0 GHz to 11.0 GHz. A higher frequency range may allow up-conversion before the circulator (114) to be removed. Alternatively, the signal generator (110) may be directly coupled to the circulator (114). However, a DAC (107) and a BPF (106) may be provided between the signal generator (110) and the circulator (114). This allows a digital signal to be generated by a signal generator (110) that is converted into an analog signal for use in measuring the properties of the plasma.

[0028] After receiving a chirp pulse signal at the first port (121), the circulator (114) propagates the signal from the second port (122) to the resonator (120). Subsequently, the reflected signal (which contains information regarding plasma properties) is propagated by the circulator (114) from the second port (122) to the third port (123). In an embodiment, the third port (123) of the circulator (114) is coupled to the RF port (117) of the mixer (116). The mixer (116) can downconvert the signal so that the signal is suitable for sampling by the sampling component (118). The mixer (116) and / or sampling component (118) of FIG. 1b may be similar to the mixer (116) and / or sampling component (118) of FIG. 1a. Additionally, it should be recognized that the mixer (116) may be arbitrary in some embodiments.

[0029] Now, referring to FIG. 1c, a schematic diagram of a sensor (102) according to an additional embodiment is shown. In an embodiment, the sensor (102) may include a resonator (120) electrically coupled to a circuit. For example, the circuit may include an RF circuit and a digital domain (109). In an embodiment, the circuit may be provided on a board such as a motherboard, a PCB, or something similar.

[0030] In an embodiment, the digital domain (109) may include a signal generator (110), a first mixer (112), and a BPF (106) as part of the input chain to the circulator (114). Additionally, a DAC (107) and an additional BPF (106) may be included between the circulator (114) and the input chain outside the digital domain (109). Similarly, a part of the output chain may be incorporated into the digital domain (109). For example, after the BPF (106) and ADC (118), the output chain may continue in the digital domain (109) to an LPF (119) and a second mixer (116). A PLL synthesizer (115) between the first mixer (112) and the second mixer (116) may also be included in the digital domain (109).

[0031] Now, referring to FIG. 2, a sequential diagram of the chirp pulse as it passes through the electrical circuit of the sensor according to an embodiment is shown. A snapshot (231) is a view of the signal immediately after it is generated by a signal generator. As shown, the signal may have a pulse length (P). For example, the pulse length (P) may be approximately 10 μs or less, approximately 5.0 μs or less, approximately 1.0 μs or less, or approximately 0.1 μs or less. In an embodiment, the signal may have a first range (R1) having a low frequency (L1) and a high frequency (H1). In an embodiment, the first range (R1) may be from 1.0 GHz to 5 GHz. In an embodiment, the low frequency (L1) may be approximately 0.01 GHz and the high frequency (H1) may be 1.0 GHz. However, it should be recognized that any first range (R1) having a suitable low frequency (L1) and high frequency (H1) may be used in other embodiments.

[0032] In the illustrated embodiments, the chirp pulse is depicted as a linear chirp. However, the embodiments are not limited to these embodiments. For example, the chirp pulse may also include an exponential chirp, a parabolic chirp, or any other non-linear signal. Additionally, while chirps having increasing frequencies are illustrated in FIG. 2, chirps may also include decreasing frequencies (i.e., negative chirps).

[0033] A snapshot (232) is a drawing of the signal after it has been modified (e.g., up-converted) after passing through the first mixer. As illustrated, the second range (R2) is higher than the first range (R1). That is, the high frequency (H2) is higher than the high frequency (H1) and / or the low frequency (L2) is higher than the low frequency (L1). In an embodiment, the bandwidth of the second range (R2) may be similar to the bandwidth of the first range (R1). For example, the second range (R2) may have a bandwidth of approximately 1 GHz at most, approximately 2 GHz at most, or approximately 5 GHz at most. In a specific embodiment, the high frequency (H2) may be approximately 11 GHz and the low frequency (L2) may be approximately 9 GHz.

[0034] The snapshot (233) is a drawing of the signal after it has been transformed (e.g., up-converted) after passing through the second mixer. As illustrated, the third range (R3) is lower than the second range (R2). That is, the high frequency (H3) is lower than the high frequency (H2) and / or the low frequency (L3) is lower than the low frequency (L2). In an embodiment, the bandwidth of the third range (R3) may be similar to the bandwidth of the first range (R1) and / or the bandwidth of the second range (R2). For example, the second range (R2) may have a bandwidth of up to approximately 1 GHz, up to approximately 2 GHz, or up to approximately 5 GHz. In a specific embodiment, the high frequency (H3) and the low frequency (L3) may be similar to the high frequency (H1) and the low frequency (L1) of the signal in the first snapshot (231). For example, the high frequency (H3) may be approximately 1.0 GHz, and the low frequency (L3) may be approximately 0.01 GHz.

[0035] Now, referring to FIG. 3, a plot of a plurality of chirp pulse signals (335A-335C) generated over a time duration according to an embodiment is shown. In an embodiment, the signals (335) may be similar to any of the chirp pulse waveforms described in more detail herein. The signals (335) may have a pulse duration (P) of approximately 1,000 μs or less, 100 μs or less, 10 μs or less, approximately 5.0 μs or less, approximately 1.0 μs or less, or approximately 0.1 μs or less. However, in some embodiments, real-time monitoring may also be applicable to pulse durations (P) of up to 100 ms (e.g., 50 ms to 100 ms). The bandwidth range (R) of the chirp may be up to 1.0 GHz, up to 2.0 GHz, or up to 5.0 GHz. For example, in some embodiments, the frequency range of the chirp pulse may include a low frequency (L) of approximately 0.01 GHz and a high frequency (H) of approximately 1.0 GHz.

[0036] As described, the chirp pulse signals (335) may be spaced apart by a time gap (G) at locations (336A and 336B). In an embodiment, the time gap (G) may be used to allow each signal (335) to pass through the system to extract useful information regarding the plasma. In an embodiment, the time gap (G) may have a duration similar to the pulse duration (P). However, in other embodiments, the time gap (G) may be larger or smaller than the pulse duration (P). In some embodiments, the time gap (G) may be from 0.5 μs to 10 μs. In another embodiment, the time gap (G) may be omitted. That is, in some embodiments, a continuous chirp signal may be used. For example, a first part of the signal may include an increasing frequency, a second part of the signal (immediately after the first part) may include a decreasing frequency, and a third part of the signal (immediately after the second part) may include an increasing frequency.

[0037] Now, referring to FIG. 4a, a plan view of a portion of a sensor (400) according to an embodiment is shown. The illustrated portion of the sensor (400) includes an electrical circuit. A resonator coupled to the electrical circuit is omitted for clarity. In the embodiment, the electrical circuit may be provided on a board (405), such as a motherboard, a PCB, or something similar. Although a single board (405) is illustrated, it should be recognized that embodiments may integrate components and circuits on two or more boards (405).

[0038] In an embodiment, the sensor (400) may include a signal generating device (410) on the board (405). The signal generating device (410) may be a digital-to-analog converter (DAC) or similar. The signal generating device (410) may be suitable for generating chirp pulse signals similar to those described in more detail herein. In some embodiments, a processor (442) (e.g., a field programmable gate array (FPGA)) may be responsible for (or partially responsible for) generating the chirp waveform. Thus, a line connecting the signal generating device (410) to the processor (442) may be used to indicate an input to the signal generating device (410). In an embodiment, the signal generating device (410) may be electrically coupled to a mixer (412). The mixer (412) may also include associated filters, transmission lines, and similar elements. In an embodiment, the mixer (412) converts the chirp pulse signal from the signal generating device (410). For example, a chirp pulse signal can upconvert the signal to a higher frequency range.

[0039] In an embodiment, the mixer (412) is coupled to the circulator (414). The circulator (414) may have a port coupled to the connector (447). The connector (447) may be any suitable I / O connector architecture for coupling with the resonator. For example, the connector (447) may be a subminiature (SMA) port. After the signal propagates to the resonator, interacts with the plasma, and is reflected back to the circulator (414), the signal is routed to another mixer (416). The mixer (416) may also include associated filters, transmission lines, and similar elements. In an embodiment, the mixer (416) downconverts the chirp pulse signal to a frequency range suitable for sampling. In an embodiment, the mixer (416) may be electrically coupled to the mixer (412) via a PLL synthesizer (415).

[0040] In an embodiment, the mixer (412) may be coupled to a sampling component (418), such as an ADC. The sampling component (418) may be electrically coupled to a processor (442). For example, the processor (442) may include an FPGA capable of performing short-time Fourier transform (STFT) operations and / or Lorentzian fit calculations before subsequent pulses are received (e.g., within 10 μs or less, within 5 μs or less, or within 1 μs or less). A real-time processing unit (RPU) (444) may be electrically coupled to the processor (442) to implement some of the processing and / or improve processing performance. The RPU (444) may be coupled to an interconnect module (446) (e.g., an ECAT module). The interconnect module (446) may include a connector interface (448). Additionally, the RPU (444) may be directly coupled to the connector interface (449). The connector interfaces (448 and 449) may provide data / signals to one or more external devices (not shown) (e.g., a computer, a server, etc.) for controlling or monitoring the plasma process and / or tool. In some embodiments, one or more controllers (not shown) for various components may also be included on the board (405) and / or on the board (405).

[0041] Now, referring to FIG. 4b, a plan view of a portion of the sensor (401) according to an embodiment is shown. The portion of the illustrated sensor (401) includes an electrical circuit. A resonator coupled to the electrical circuit is omitted for clarity. In the embodiment, the electrical circuit may be provided on a board (405), such as a motherboard, a PCB, or something similar. In the embodiment, the sensor (401) may be similar to the sensor (400) shown in FIG. 4a, and the mixers (e.g., a first mixer (412) and a second mixer (416)) and the PLL (415) are omitted. Instead of using mixers, a doubler is used to increase the frequency of the chirp pulse. For example, the frequency can be doubled up to approximately 8.0 GHz. The doubler may be integrated into a processor (442) to supply a higher frequency chirp to a DAC. RF transmission lines (445 and 443) can replace the first mixer (412) and the second mixer (416). Such embodiments may enable pulse durations at shorter ends of the ranges described herein (e.g., 1.0 μs or less or 0.5 μs or less). Shorter pulses may allow higher measurement bandwidths or improved measurement time resolution. However, the sampling component (418) may need to have increased performance to accommodate faster sampling rates.

[0042] Now, referring to FIG. 5a, a cross-sectional view of a tool (550) according to an embodiment is shown. In some cases, the tool (550) may be a semiconductor processing tool. For example, the tool (550) may be a deposition chamber (e.g., chemical vapor deposition (CVD), atomic layer deposition (ALD), physical vapor deposition (PVD), etc.), an etching chamber, a plasma processing chamber, or something similar. More generally, the tool (550) may be suitable for supporting a plasma (556).

[0043] In an embodiment, the tool (550) may include a chamber (552). The chamber may include inlets, exhaust ports, etc. (not shown) for flowing gases into and out of the chamber. In an embodiment, the tool (550) may include a pedestal (554) for supporting a substrate (555). The pedestal (554) may include features (e.g., electrostatic chucking features) for securing the substrate (555) as well as thermal control features (e.g., heaters, coolant loops, etc.). The substrate (555) may be a semiconductor wafer, such as a silicon wafer. However, any substrate may be processed in the tool (550).

[0044] In an embodiment, the sensor (500) may be integrated with the tool (550). In FIG. 5a, the sensor (500) includes a resonator component (562) provided within the chamber (552). For example, the resonator component (562) may be provided on the sidewall of the chamber (552). This embodiment may be suitable for HVM environments because the resonator component (562) does not substantially interfere with the processing of the substrate (556). Although shown as being on the sidewall of the chamber (552), it should be recognized that the resonator component (562) may be provided on any internal surface of the chamber (552).

[0045] In an embodiment, the resonator component (562) may be coupled to a board (505) located outside the chamber (552) by a link (563) passing through the wall of the chamber (552). The board (505) may include electrical components and circuits similar to those in embodiments described in more detail herein. For example, the electrical circuit may include a signal generator for generating chirp pulses to enable real-time measurement of the plasma (556).

[0046] Now, referring to FIG. 5b, a cross-sectional view of a tool (551) according to an additional embodiment is shown. The tool (551) may be similar to the tool (550) of FIG. 5a, except for the sensor (500). Instead of providing a resonator component (562) on the side wall of the chamber (552), the resonator component (556) is extended toward the center of the chamber (552) by a probe arm (564). The probe arm (564) may be coupled to a link (563) passing through the wall of the chamber (552). This embodiment may be more suitable for research and development setups or other non-production monitoring environments because the probe arm (564) and the resonator component (556) can perturb the plasma (556) to alter the processing conditions of the lower substrate (555).

[0047] Now, referring to FIG. 6, a top view of a sensor (600) according to an additional embodiment is shown. In an embodiment, the sensor (600) may be integrated on a substrate (665). The substrate (665) may be sized to be inserted into and removed from plasma processing chambers. Thus, a single sensor (600) may be circulated through a plurality of chambers and / or tools to provide plasma monitoring. In an embodiment, the substrate (665) may be any suitable substrate material. In one embodiment, the substrate (665) may comprise a semiconductor material. Other embodiments may comprise PCB materials, metals (e.g., stainless steel, titanium, etc.) and / or similar materials.

[0048] In an embodiment, one or more resonators (662) may be provided on the substrate (665). In some embodiments, the resonators (662) may be adjacent to ground planes (667). Although a specific structure for the resonators (662) is illustrated, it should be recognized that any resonant structure may be used in the sensor (600). In an embodiment, a board (605) may be provided on the substrate (665). The board (605) may house electrical components and structures to enable real-time monitoring of the plasma. For example, a signal generator may generate chirp pulses. Also, although illustrated as a separate component, it should be recognized that the board (605) may be omitted. In such cases, electrical components and / or structures may be fabricated directly on the substrate (665), particularly when the substrate (665) comprises PCB materials.

[0049] Now, referring to FIG. 7, a process flowchart of a process (770) for measuring plasma properties according to an embodiment is illustrated. In the embodiment, the process (770) may be initiated by an operation (771), the operation (771) includes generating a chirp carrier signal. In the embodiment, the chirp carrier signal may have a pulse length of up to 100 ms. The chirp carrier signal may be similar to any of the chirp signals described in more detail herein.

[0050] In an embodiment, the process (770) may continue to an operation (772), the operation (772) includes providing a chirped carrier signal to a resonator for interaction with the plasma. In an embodiment, the plasma-modified resonant frequency of the resonator is measured by the reflected chirped carrier signal. In an embodiment, information regarding plasma properties is encoded on the chirped carrier signal within the reflected signal. The resonator may be provided within a plasma chamber similar to any of the chamber configurations described in more detail herein.

[0051] In an embodiment, the process (770) may continue to an operation (773), the operation (773) comprising extracting plasma properties from a reflected signal in real-time or near real-time. In an embodiment, the plasma properties are extracted through the use of a sampling component, such as an ADC or similar. In an embodiment, the plasma properties may be related to the frequency of the plasma added to the chirp carrier signal. For example, the plasma properties may include plasma electron density, electron temperature, or similar properties.

[0052] Now, referring to FIG. 8, a process flowchart of a process (880) for measuring plasma properties according to an embodiment is illustrated. In an embodiment, the process (880) may be initiated by an operation (881), the operation (881) comprising generating a chirp carrier signal having a first frequency range. The chirp carrier signal may be similar to any of the chirp signals described in more detail herein. In a particular embodiment, the first frequency range may be from 0.01 GHz to 1.0 GHz.

[0053] In an embodiment, the process (880) may continue to an operation (882), the operation (882) includes converting a first frequency range to a second frequency range higher than the first frequency range. In an embodiment, the conversion may be implemented by a mixer or similar. In an embodiment, the second frequency range may have a lower frequency higher than the high frequency of the first frequency range. In a specific embodiment, the second frequency range may be 9.0 GHz to 11.0 GHz.

[0054] In an embodiment, the process (880) may continue to an operation (883), the operation (883) includes providing a chirped carrier signal to a resonator for interaction with the plasma. In an embodiment, the plasma-modified resonant frequency of the resonator is measured by the reflected chirped carrier signal. In an embodiment, information regarding plasma properties is encoded on the chirped carrier signal within the reflected signal. The resonator may be provided within a plasma chamber similar to any of the chamber configurations described in more detail herein.

[0055] In an embodiment, the process (880) may continue to an operation (884), the operation (884) includes converting the reflected signal to a third frequency range lower than the second frequency range. For example, the high frequency of the third frequency range may be lower than the low frequency of the second frequency range. In some embodiments, the third frequency range may be similar to or identical to the first frequency range. In an embodiment, the conversion to the third frequency range may be implemented by a mixer or similar. In some embodiments, the mixer used in operation (882) may be coupled to the mixer used in operation (884) through a PLL or similar.

[0056] In an embodiment, the process (880) may continue to an operation (885), the operation (885) comprising extracting plasma properties from a reflected signal in real-time or near real-time. In an embodiment, the plasma properties are extracted through the use of a sampling component, such as an ADC or similar. In an embodiment, the plasma properties may relate to changes in resonance frequency resulting from the interaction between the plasma and the resonators, measured by a chirp carrier signal. For example, the plasma properties may include plasma electron density, electron temperature, or similar properties.

[0057] In the embodiments described in more detail herein, applications including plasma monitoring are described in detail. However, it should be recognized that similar circuits may be used to determine the properties of different states of matter (e.g., gases, liquids, or solids) using dielectric spectroscopy methods.

[0058] Now, referring to FIG. 9, a block diagram of an exemplary computer system (900) of a processing tool is illustrated according to an embodiment. In an embodiment, the computer system (900) is coupled to the processing tool and controls processing within the processing tool. The computer system (900) may be connected (e.g., networked) to other machines in a local area network (LAN), intranet, extranet, or the Internet. The computer system (900) may operate as a server or client machine in a client-server network environment or as a peer machine in a peer-to-peer (or distributed) network environment. The computer system (900) may be a personal computer (PC), tablet PC, set-top box (STB), personal digital assistant (PDA), cellular phone, web device, server, network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by the machine. Additionally, although only a single machine is exemplified for the computer system (900), the term “machine” should also be understood to include any set of machines (e.g., computers) that execute a set (or a number of sets) of instructions individually or collectively to perform any one or more of the methods described herein.

[0059] A computer system (900) may include a computer program product or software (922) having a non-transient machine-readable medium that stores instructions that can be used to program the computer system (900) (or other electronic devices) to perform a process according to embodiments. The machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, a machine-readable (e.g., computer-readable) medium includes a machine-readable storage medium (e.g., read-only memory (“ROM”), random access memory (“RAM”), magnetic disk storage media, optical storage media, flash memory devices, etc.), a machine-readable transmission medium (electrical, optical, acoustic, or other forms of radio signals (e.g., infrared signals, digital signals, etc.)), etc.

[0060] In an embodiment, the computer system (900) includes a system processor (902), main memory (904) (e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM), such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM), etc.), static memory (906) (e.g., flash memory, static random access memory (SRAM), etc.), and secondary memory (918) (e.g., data storage device), and they communicate with each other via a bus (930).

[0061] The system processor (902) represents one or more general-purpose processing devices, such as a microsystem processor, a central processing unit, or similar devices. More specifically, the system processor may be a complex instruction set computing (CISC) microsystem processor, a reduced instruction set computing (RISC) microsystem processor, a very long instruction word (VLIW) microsystem processor, a system processor implementing other instruction sets, or a system processor implementing a combination of instruction sets. The system processor (902) may also be one or more special-purpose processing devices, such as an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal system processor (DSP), a network system processor, or similar devices. The system processor (902) is configured to execute processing logic (926) for performing the operations described herein.

[0062] The computer system (900) may further include a system network interface device (908) for communicating with other devices or machines. The computer system (900) may also include a video display unit (910) (e.g., a liquid crystal display (LCD), a light-emitting diode display (LED), or a cathode ray tube (CRT)), an alphanumeric input device (912) (e.g., a keyboard), a cursor control device (914) (e.g., a mouse), and a signal generating device (916) (e.g., a speaker).

[0063] The secondary memory (918) may include a machine-accessible storage medium (932) (or more specifically, a computer-readable storage medium) in which one or more sets of instructions (e.g., software (922)) that perform any one or more of the methods or functions described herein are stored. The software (922) may also reside in the system processor (902) and / or in the main memory (904) in whole or at least partially during its execution by the computer system (900), and the main memory (904) and the system processor (902) also constitute machine-readable storage media. Additionally, the software (922) may be transmitted or received through the network (960) via the system network interface device (908). In an embodiment, the network interface device (908) may operate using RF coupling, optical coupling, acoustic coupling, or inductive coupling.

[0064] Although the machine-accessible storage medium (932) is depicted as a single medium in exemplary embodiments, the term “machine-readable storage medium” should be understood to include a single medium or multiple media (e.g., centralized or distributed databases and / or associated caches and servers) that store one or more sets of instructions. The term “machine-readable storage medium” should also be understood to include any medium capable of storing or encoding a set of instructions for execution by a machine and enabling the machine to perform any one or more of the methods. Accordingly, the term “machine-readable storage medium” should be understood to include, but not be limited to, solid-state memories and optical and magnetic media.

[0065] In the foregoing description, specific exemplary embodiments have been described. It will be apparent that various modifications may be made to the embodiments without departing from the scope of the following claims. Accordingly, this specification and drawings should be conceived as exemplary rather than restrictive.

Claims

Claim 1 A device comprising: a board; a signal generator for generating chirped signals on the board; a first mixer on the board and electrically coupled to the signal generator; a circulator on the board — the circulator comprises a first port electrically coupled to the mixer, a second port electrically coupled to a connector, and a third port —; a second mixer on the board and electrically coupled to the third port of the circulator; and an analog-to-digital converter (ADC) on the board and electrically coupled to the second mixer. Claim 2 The device according to claim 1, further comprising a phase-locked loop (PLL) synthesizer on the board and electrically coupled between the first mixer and the second mixer. Claim 3 In claim 1, the device is configured such that the signal generator generates the chirp signal having a pulse length of up to 100 ms. Claim 4 A device according to claim 1, wherein the chirp signal is a linear chirp, an exponential chirp, or a hyperbolic chirp. Claim 5 A device according to claim 1, wherein the chirp signal has a frequency range having a low frequency of up to 0.01 GHz and a high frequency of up to 10.0 GHz. Claim 6 A device according to claim 1, wherein the first mixer is configured to up-convert a signal and the second mixer is configured to down-convert the signal. Claim 7 The device according to claim 1, further comprising a low-pass filter on the board and electrically coupled between the signal generator and the first mixer, and / or a high-pass filter on the board and electrically coupled between the first mixer and the circulator. Claim 8 A method for monitoring plasma properties in real time, comprising: generating a chirp signal having a first frequency range; converting the first frequency range to a second frequency range higher than the first frequency range; providing the chirp signal to a resonator for interaction with the plasma — the plasma-modified resonant frequency of the resonator is measured by a reflected chirp carrier signal —; converting the reflected signal to a third frequency range lower than the second frequency range; and extracting plasma properties from the reflected signal. Claim 9 In claim 8, the method wherein the chirp signal comprises a pulse length of up to 100 ms. Claim 10 In paragraph 8, the plasma properties are plasma electron density and / or electron temperature, method. Claim 11 In paragraph 8, the method wherein the resonator is a microwave resonator probe. Claim 12 A method according to claim 8, wherein the first frequency range has a low frequency of up to 0.01 GHz and a high frequency of up to 1.0 GHz, and the second frequency range has a low frequency of up to 9.0 GHz and a high frequency of up to 11.0 GHz. Claim 13 In claim 8, the chirp signal is one of a series of chirps, and each chirp is spaced apart by a duration of up to 10 μs. Claim 14 In paragraph 8, the chirp signal is a linear chirp, an exponential chirp, or a hyperbolic chirp. Claim 15 A tool comprising: a chamber suitable for generating plasma; a pedestal within the chamber to support a substrate; and a sensor at least partially within the chamber to measure plasma properties, wherein the sensor, Resonator or transmission line; and A tool comprising an RF circuit coupled to the above-mentioned resonator, wherein the RF circuit is configured to generate chirp pulses supplied to the above-mentioned resonator. Claim 16 In paragraph 15, the tool, wherein the resonator is provided along the wall of the chamber and the RF circuit is coupled to the resonator through a link passing through the wall of the chamber. Claim 17 In paragraph 15, the sensor is a tool integrated into a substrate supported on the pedestal. Claim 18 In paragraph 15, the RF circuit comprises: a board; a direct digital synthesizer (DDS) on the board; a first mixer on the board and electrically coupled to the DDS; a circulator on the board — the circulator comprises a first port electrically coupled to the mixer, a second port electrically coupled to a connector, and a third port —; a second mixer on the board and electrically coupled to the third port of the circulator; and an analog-to-digital converter (ADC) on the board and electrically coupled to the second mixer. Claim 19 In paragraph 15, the tool is configured such that the sensor measures the resonant frequency shift of the resonator induced by interaction with the plasma or the frequency of the plasma generated within the chamber using the transmission line. Claim 20 In paragraph 19, the frequency of the plasma or the resonant frequency shift is a tool used to measure plasma properties.

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