Method and apparatus for processing a substrate - Patents.com

Abstract

Methods and apparatuses for processing a substrate are provided herein, for example, a matching network configured for use with a plasma processing chamber, comprising an input configured to receive one or more radio frequency (RF) signals, an output configured to deliver one or more RF signals to the processing chamber, a first sensor operably connected to the input and a second sensor operably connected to the output and configured to measure impedance during operation, at least one variable capacitor connected to the first sensor and the second sensor, and a controller configured to tune the at least one variable capacitor of the matching network to a first target position based on weighted output impedance values ​​measured during a pulsed state of a voltage waveform and tune the at least one variable capacitor to a second target position based on weighted input impedance values ​​measured during a pulsed state of a voltage waveform based on the measured impedance.

Description

[Technical field]

[0001] Embodiments of the present disclosure generally relate to methods and apparatus for processing a substrate, for example, using weighted average tuning in a radio frequency (RF) matching network configured for use with an RF processing chamber. [Background technology]

[0002] Methods and apparatus are known for processing a substrate in a vacuum processing chamber using one or more of the RF power supplies (e.g., one or more RF power supplies can be configured for single level pulsing, dual level pulsing, or multi-level pulsing). For example, in single level pulsing (e.g., pulsing between an on state and an off state), there is only one state to regulate (e.g., an on state). However, in dual level pulsing, the RF power supply is switched between a high state and a low state (the low state is not, for example, an off state). In multi-level pulsing, the RF power supply can be switched between multiple states.

[0003] An RF matching network is often connected between the RF power source and the vacuum processing chamber and configured to ensure that the output of the RF power source is efficiently coupled to the plasma to maximize the amount of energy coupled to the plasma (e.g., referred to as regulating the RF power supply). For example, in dual-level pulsing, there are two or more impedance states that require impedance matching. Current RF matching networks are configured to tune to one state in time average and perform frequency tuning in the other state in real time using electromotive capacitors (e.g., in series or shunt). However, frequency tuning is limited in impedance matching due to single-axis tuning, which may result in limited process capability and increased reflected power. Furthermore, the plasma load impedance state may vary due to pulsed power levels, e.g., bias power on and off, or pulse voltage waveforms. Motors in RF matching cannot follow the rapidly changing impedance states. For example, conventional RF matching networks are configured to match to the first state in multi-level pulsing. For example, in ultrafast pulsed signals or pulse voltage waveforms, e.g., on a microsecond time scale, frequency tuning may not follow the plasma impedance variations and may not even tune well within the pulse cycle.

[0004] Accordingly, the inventors have provided herein an improved method and apparatus for processing substrates using weighted average tuning in a radio frequency (RF) matching network configured for use with an RF processing chamber. Summary of the Invention

[0005] Methods and apparatuses for processing a substrate are provided herein. For example, in some embodiments, a matching network configured for use with a plasma processing chamber comprises an input configured to receive one or more radio frequency (RF) signals, an output configured to send one or more RF signals to the processing chamber, a first sensor operably connected to the input, and a second sensor operably connected to the output and configured to measure impedance during operation, at least one variable capacitor connected to the first sensor and the second sensor, and a controller configured to tune the at least one variable capacitor of the matching network to a first target position based on a weighted output impedance value measured in a pulsed state and tune the at least one variable capacitor to a second target position based on a weighted input impedance value measured in a pulsed state based on the measured impedance.

[0006] According to at least some embodiments, a plasma processing chamber comprises a chamber body and a chamber lid, an RF source power connected to the chamber lid and configured to create a plasma from a gas disposed in a processing region of the chamber body, one or more RF bias power supplies configured to sustain a plasma discharge, and a matching network, the matching network comprising an input configured to receive one or more radio frequency (RF) signals, an output configured to deliver one or more RF signals to the processing chamber, a first sensor operably connected to the input and a second sensor operably connected to the output and configured to measure impedance during operation, at least one variable capacitor connected to the first sensor and the second sensor, and a controller configured to tune the at least one variable capacitor of the matching network to a first target position based on a weighted output impedance value measured in a pulsed state and to tune the at least one variable capacitor to a second target position based on a weighted input impedance value measured in a pulsed state based on the measured impedance.

[0007] According to at least some embodiments, a method for processing a substrate includes measuring impedance at an input of a matching network configured to receive one or more radio frequency (rf) signals and at an output of the matching network configured to deliver one or more rf signals to a processing chamber, and based on the measured impedance, tuning at least one variable capacitor of the matching network to a first target position based on weighted output impedance values ​​measured in a pulsed state and tuning at least one variable capacitor to a second target position based on weighted input impedance values ​​measured in a pulsed state.

[0008] Other and further embodiments of the present disclosure are described below.

[0009] Embodiments of the present disclosure, briefly summarized above and described in more detail below, can be understood by reference to the exemplary embodiments of the present disclosure that are illustrated in the accompanying drawings, which, however, depict only typical embodiments of the present disclosure and therefore should not be considered limiting in scope, since the present disclosure may admit of other equally effective embodiments. [Brief description of the drawings]

[0010] [Figure 1] 1 illustrates a cross-sectional view of a processing chamber in accordance with at least some embodiments of the present disclosure. [Diagram 2] FIG. 1 is a diagram of a system, in accordance with at least some embodiments of the present disclosure. [Diagram 3] FIG. 2 is a diagram of a matching network according to some embodiments of the present disclosure. [Figure 4] 1 is a graph of sampling impedance, in accordance with at least some embodiments of the present disclosure. [Diagram 5] FIG. 1 is a diagram of a system, in accordance with at least some embodiments of the present disclosure. [Figure 6]FIG. 13 is a diagram of internal synchronization for dual level pulsing, in accordance with at least some embodiments of the present disclosure. [Figure 7] 1 is a flowchart of a method for processing a substrate in accordance with at least some embodiments of the present disclosure.

[0011] For ease of understanding, the same reference numbers have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Embodiments of a method and apparatus for processing a substrate are provided herein. For example, a matching network configured for use with a plasma processing chamber may include an input configured to receive one or more radio frequency (RF) signals, and an output may be configured to send one or more RF signals to the processing chamber. A first sensor may be operably connected to the input, and a second sensor may be operably connected to the output and configured to measure impedance during operation. At least one variable capacitor may be connected to the first sensor and the second sensor. A controller may be configured to tune at least one variable capacitor of the matching network to a first target position based on a weighted output impedance value measured in a pulsed state, and tune at least one variable capacitor to a second target position based on a weighted input impedance value measured in a pulsed state, based on the measured impedance. Advantages of the apparatus and methods described herein include, but are not limited to, tuning optimized weighted plasma impedance values ​​to achieve minimum total reflected power for all states during multi-level pulsing, spatial power distribution and uniformity, and flexibility to define tuning targets based on different process and pulsing conditions.

[0013] 1 is a cross-sectional view of one example of a processing chamber 100 suitable for performing an etching process according to the present disclosure. Suitable processing chambers that may be adapted for use with the teachings disclosed herein include, for example, one or more etch processing chambers available from Applied Materials, Inc. of Santa Clara, Calif. Other processing chambers may be adapted to benefit from one or more of the methods of the present disclosure.

[0014] The processing chamber 100 includes a chamber body 102 and a chamber lid 104 that encloses an internal volume 106. The chamber body 102 is typically fabricated from aluminum, stainless steel, or other suitable material. The chamber body 102 generally includes a sidewall 108 and a bottom 110. A substrate support pedestal access port (not shown) is typically defined in the sidewall 108 and selectively sealed by a slit valve to facilitate passage of the substrate 103 out of the processing chamber 100. An exhaust port 126 is defined in the chamber body 102 and couples the internal volume 106 to a pumping system 128. The pumping system 128 generally includes one or more pumps and a throttle valve that are utilized to vent and adjust the pressure of the internal volume 106 of the processing chamber 100. In embodiments, the pump system 128 maintains the pressure within the internal volume 106 at an operating pressure, typically between about 1 mTorr and about 500 mTorr, between about 5 mTorr and about 100 mTorr, or between about 5 mTorr and about 50 mTorr, depending on process needs.

[0015] In an embodiment, the chamber lid 104 may be sealingly supported on a sidewall 108 of the chamber body 102. The chamber lid 104 may be opened to allow overfilling of the interior volume 106 of the processing chamber 100. The chamber lid 104 includes a window 142 to facilitate optical process monitoring. In one embodiment, the window 142 is constructed of quartz or other suitable material that is transparent to signals utilized by an optical monitoring system 140 mounted outside of the processing chamber 100.

[0016] The optical monitoring system 140 is positioned to view at least one of the interior volume 106 of the chamber body 102 and / or the substrate 103 disposed on the substrate support pedestal assembly 148 through a window 142. In one embodiment, the optical monitoring system 140 is coupled to the chamber lid 104 and facilitates an integrated deposition process that uses optical metrology to provide information enabling process adjustments, if necessary, to compensate for inconsistencies in incoming substrate pattern features (e.g., thickness) and to provide process state monitoring (plasma monitoring, temperature monitoring, etc.).

[0017] Process and / or cleaning gases may be introduced into the interior volume 106 of the chamber body 102 through a showerhead assembly 130 from a gas panel 158 coupled to the processing chamber 100. A vacuum pumping system, such as pump system 128, maintains pressure within the chamber body 102 while removing deposition by-products.

[0018] In the example shown in FIG. 1 , inlet ports 132′, 132″ are provided in the chamber lid 104 to allow gas to be delivered to the interior volume 106 of the processing chamber 100 from a gas panel 158. In an embodiment, the gas panel 158 is adapted to provide oxygen and an inert gas, such as argon, or oxygen and helium process gas or a mixed gas, to the interior volume 106 of the processing chamber 100 through the inlet ports 132′, 132″. In one embodiment, the process gas provided from the gas panel 158 includes at least a process gas including an oxidizer, such as oxygen gas. In an embodiment, the process gas including an oxidizer may further include an inert gas, such as argon or helium. In some embodiments, the process gas includes a reducing agent, such as hydrogen, and may be mixed with an inert gas, such as argon, or other gas, such as nitrogen or helium. In some embodiments, chlorine gas may be provided alone or in combination with at least one of an inert gas, such as nitrogen, helium, argon, etc. Non-limiting examples of oxygen-containing gases include O 2 , CO 2 , N 2 O, NO 2 , O 3 , H 2 Non-limiting examples of nitrogen-containing gases include N 2 , N.H. 3 Non-limiting examples of chlorine-containing gases include HCl, Cl 2 , CCl 4 etc. In an embodiment, a showerhead assembly 130 is coupled to the interior surface 114 of the chamber lid 104. The showerhead assembly 130 includes a plurality of apertures that allow gases to flow from inlet ports 132′, 132″ through the showerhead assembly 130 and into the interior volume 106 of the processing chamber 100 in a predefined distribution across the surface of the substrate 103 being processed in the processing chamber 100.

[0019] In some embodiments, the processing chamber 100 may utilize capacitively coupled RF energy for plasma processing, or in some embodiments, the processing chamber 100 may use inductively coupled RF energy for plasma processing. In some embodiments, a remote plasma source 177 may be optionally coupled to the gas panel 158 to facilitate separating the gas mixture from the remote plasma prior to entering the internal volume 106 for processing. In some embodiments, the RF source power 143 is coupled to the showerhead assembly 130 through a matching network 141. The RF source power 143 may generally be generated up to about 5000 W, for example, between about 200 W and about 5000 W, or between 1000 W and 3000 W, or about 1500 W, and optionally at a tunable frequency within a range of about 50 kHz to about 200 MHz.

[0020] The showerhead assembly 130 further includes an area that is transparent to the optical metrology signals. The optically transparent area or passage 138 is suitable for allowing the optical monitoring system 140 to view the interior volume 106 and / or the substrate 103 disposed on the substrate support pedestal assembly 148. The passage 138 may be a material, one or more apertures formed or disposed in the showerhead assembly 130 that is substantially transparent to the wavelengths of energy provided by and reflected to the optical monitoring system 140. In one embodiment, the passage 138 includes a window 142 to prevent gas leakage through the passage 138. The window 142 may be a sapphire plate, a quartz plate, or other suitable material. The window 142 may alternatively be disposed in the chamber lid 104.

[0021] The showerhead assembly 130 may be configured with multiple zones that allow separate control of gases flowing into the interior volume 106 of the processing chamber 100. In the example shown in FIG. 1, the showerhead assembly 130 is configured with an inner zone 134 and an outer zone 136 that are separately coupled to a gas panel 158 through inlet ports 132′, 132″.

[0022] A substrate support pedestal assembly 148 is disposed within the interior volume 106 of the processing chamber 100 below a gas distribution assembly, such as the showerhead assembly 130. The substrate support pedestal assembly 148 holds the substrate 103 during processing. The substrate support pedestal assembly 148 generally includes a plurality of lift pins (not shown) disposed therethrough that are configured to lift the substrate 103 from the substrate support pedestal assembly 148 and facilitate exchange of the substrate 103 by a robot (not shown) in a conventional manner. An inner liner 118 may closely circumscribe the periphery of the substrate support pedestal assembly 148.

[0023] The substrate support pedestal assembly 148 includes a mounting plate 162, a base 164, and an electrostatic chuck 166. The mounting plate 162 is coupled to the bottom 110 of the chamber body 102 and includes passages for routing utilities, such as fluids, power lines, and sensor leads, among other things, to the base 164 and the electrostatic chuck 166. The electrostatic chuck 166 includes an electrode 180 (e.g., a clamping electrode) for holding the substrate 103 below the showerhead assembly 130. The electrostatic chuck 166 is powered by a chuck power supply 182 to generate an electrostatic force that holds the substrate 103 against the chuck surface, as is known in the art. Alternatively, the substrate 103 may be held against the substrate support pedestal assembly 148 by clamps, vacuum, or gravity.

[0024] The base 164 or electrostatic chuck 166 may include a heater 176, at least one optional embedded isolator 174, and a number of conduits 168, 170 to control a lateral temperature profile of the substrate support pedestal assembly 148. The conduits 168, 170 are fluidly coupled to a fluid source 172 that circulates a temperature regulating fluid therethrough. The heater 176 is regulated by a power supply 178. The conduits 168, 170 and heater 176 are utilized to control the temperature of the base 164, to control the heating and / or cooling of the electrostatic chuck 166, and ultimately to control the temperature profile of the substrate 103 disposed on the electrostatic chuck 166. The temperatures of the electrostatic chuck 166 and base 164 may be monitored using a number of temperature sensors 190, 192. The electrostatic chuck 166 may further include a number of gas passages, such as grooves (not shown), formed in a substrate support pedestal support surface of the electrostatic chuck 166 and fluidly coupled to a source of heat transfer (or backside) gas, such as helium (He). During operation, a backside gas is provided in the gas passages at a controlled pressure to enhance heat transfer between the electrostatic chuck 166 and the substrate 103. In an embodiment, the temperature of the substrate may be maintained between 20 degrees Celsius and 450 degrees Celsius, such as between 100 degrees Celsius and 300 degrees Celsius, or between 150 degrees Celsius and 250 degrees Celsius.

[0025] The substrate support pedestal assembly 148 may be configured as a cathode assembly and includes an electrode 180 coupled to a number of RF bias power supplies 184, 186. The RF bias power supplies 184, 186 are coupled between the electrode 180 disposed in the substrate support pedestal assembly 148 and another electrode, such as the showerhead assembly 130 of the chamber body 102 (or the chamber lid 104). The RF bias power excites and sustains a plasma discharge formed from gases disposed in the processing region of the chamber body 102.

[0026] Still referring to FIG. 1, in some embodiments, the dual RF bias power supplies 184, 186 are coupled to an electrode 180 disposed in the substrate support pedestal assembly 148 through a matching network 188. The signals provided by the RF bias power supplies 184, 186 are delivered through a single feed to the substrate support pedestal assembly 148 through the matching network 188 to ionize a gas mixture provided in a plasma processing chamber, such as the processing chamber 100, thus providing the necessary ion energy to perform an etch deposition or other plasma enhanced process. The RF bias power supplies 184, 186 are generally capable of generating RF signals having a frequency from about 50 kHz to about 200 MHz (e.g., about 13.56 MHz + / - 5%) and a power between about 0 watts to about 10,000 watts (e.g., from about 50 W for low power operation to about 10,000 W for high power operation), 1 watt (W) to about 100 W, or between about 1 W to about 30 W. Additional bias power may be coupled to the electrode 180 to control the characteristics of the plasma.

[0027] In at least some embodiments, the impedance at the input and output ports of the matching network 188 and / or the matching network 141 may be measured in all states in multi-level pulsing. The impedance at the input and output ports of the matching network may be used to determine weighted input and output impedances for tuning. For example, the apparatus and methods described herein use weighted average tuning in multi-level pulsing. In at least some embodiments, a weighted combination of measured output impedances may be selected for feed-forward tuning, and weighted impedances may be defined from the input impedances measured in the multi-level pulsing states. Furthermore, in at least some embodiments, frequency tuning may be used with weighted average tuning for hybrid tuning. The matching networks described herein may receive a TTL synchronization signal from the RF generator and / or the advanced waveform generator 202, as described in more detail below. Alternatively or additionally, the matching network may receive a TTL synchronization signal that is internally triggered on a detected pulse rising edge.

[0028] A controller 150 is coupled to the processing chamber 100 for controlling the operation of the processing chamber 100. The controller 150 includes a central processing unit 152, a memory 154, and support circuits 156 that are utilized to control process sequences and regulate gas flows from a gas panel 158. The central processing unit 152 may be any form of general-purpose computer processor that may be used in an industrial setting. Software routines may be stored in the memory 154, such as random access memory, read-only memory, floppy or hard disk drives, or other forms of digital storage. The support circuits 156 are conventionally coupled to the central processing unit 152 and may include cache, clock circuits, input / output systems, power supplies, and the like. Bidirectional communication between the controller 150 and the various components of the processing chamber 100 is handled through a number of signal cables.

[0029] FIG. 2 is a diagram of a system 200 in accordance with at least some embodiments of the present disclosure.

[0030] For example, in at least some embodiments, one or more RF power supplies (e.g., RF bias power supply 184 and / or RF source power 143) may be configured to supply RF power for plasma generation to an RF base plate (e.g., electrostatic chuck 166) of the cathode assembly. In such embodiments, the upper electrode (e.g., showerhead assembly 130 (or chamber lid 104)) may be grounded. The frequency of the one or more RF power supplies may be from 13.56 MHz to an ultra-high frequency band such as 60 MHz, 120 MHz, or 162 MHz. In at least some embodiments, the one or more RF power supplies may also be supplied through the upper electrode. The one or more RF power supplies may be operated in a continuous mode or a pulsed mode. For example, in a pulsed mode, the pulse frequency may be from 100 Hz to about 10 kHz and the duty cycle may be from about 5% to about 95%.

[0031] An RF impedance matching network, e.g., matching network 188 and / or matching network 141, is connected between one or more RF power supplies and processing chamber 100 to optimize power supply efficiency. The matching network is configured for use with a plasma processing chamber, e.g., a physical vapor deposition chamber, a chemical vapor deposition chamber, an atomic layer deposition, an etch chamber, or other processing chamber that employs a matching network. For purposes of explanation, the matching networks (e.g., matching network 141 and / or matching network 188) are described herein with respect to an etch chamber, e.g., processing chamber 100.

[0032] The matching network includes an input stage 201 configured to connect to one or more RF power supplies (e.g., RF bias supplies 184, 186) of a plasma processing chamber and configured to receive one or more radio frequency (RF) signals. The matching network also includes an output stage 203 configured to connect to a substrate support pedestal assembly (e.g., substrate support pedestal assembly 148) of the processing chamber and configured to deliver one or more RF signals to the processing chamber.

[0033] The matching network includes one or more variable (tunable) capacitors, such as a first variable capacitor 205 (e.g., as a series variable capacitor) and a second variable capacitor 207 (e.g., a shunt variable capacitor), which may be connected in series or in parallel with each other. The first variable capacitor 205 and the second variable capacitor 207 have a variable capacitance that allows the first variable capacitor 205 and the second variable capacitor 207 to be tuned to one or more frequencies. For example, in at least some embodiments, the first variable capacitor 205 and the second variable capacitor 207 can have a capacitance of about 3 pF to about 2500 pF. In at least some embodiments, such as when the processing chamber is operating in a high power state or a low power state, the first variable capacitor 205 and the second variable capacitor 207 can be tuned to one or more of the frequencies described above, such as a target frequency +-10%, and a target frequency from 100 kHz to about 250 MHz.

[0034] In at least some embodiments, one or more additional capacitors, inductors, transistors, etc. (not shown) may also be provided and connected in parallel and / or in series with the first variable capacitor 205 and the second variable capacitor 207.

[0035] The first variable capacitor 205 and the second variable capacitor 207 may be the same as each other or different from each other. In at least some embodiments, the first variable capacitor 205 may be coupled to the output stage 203 and the second variable capacitor 207 may be connected to the input stage 201, or vice versa.

[0036] In at least some embodiments, one or more RF filters may be connected to the matching network to allow power in selected frequency ranges and to isolate the RF sources from each other. For example, in at least some embodiments, an RF filter 204 is connected to the matching network 188 and to the substrate support pedestal assembly 148.

[0037] In at least some embodiments, an advanced waveform generator 202 may be used to provide one or more waveforms (e.g., a pulsed voltage waveform and / or a tailored voltage waveform, which may be a sum of harmonic frequencies associated with the tailored voltage waveform). The one or more voltage waveforms may be coupled to a bias electrode (e.g., the electrode 180 of the substrate support pedestal assembly 148) through one or more filter assemblies. For example, in at least some embodiments, an RF filter 206 is connected to the advanced waveform generator 202 and to the electrode 180. The advanced waveform generator 202 may output a synchronization signal to the matching network 188. For example, in at least some embodiments, the synchronization signal may be a transistor-transistor logic (TTL) 209 signal, as described in more detail below. Alternatively or additionally, the RF source power may be configured to output a synchronization signal to the matching network 188. Alternatively or additionally, the matching network may be configured to provide an internal synchronization signal, as described in more detail below.

[0038] 3 is a diagram of a matching network 188 configured for use with the processing chamber 100, in accordance with at least some embodiments of the present disclosure. In at least some embodiments, the matching network 188 can be an L-type or a π-type matching network.

[0039] The matching network 188 comprises a local controller, one or more sensors, and one or more electromotive capacitors, all of which are connected via EtherCAT (shown by dashed line 301). EtherCAT is a real-time industrial Ethernet protocol, and with short cycle times and low jitter, EtherCAT provides fast and accurate synchronization during plasma processing. One or more other interfaces may be used to connect the components of the matching network 188 to each other and / or to connect an RF generator and a plasma processing chamber to the matching network 188. For example, a transmission line 303 (shown by a solid line) may be used to connect an RF generator to the matching network 188 and to connect the matching network 188 to a plasma processing chamber, for example, to supply RF power to the plasma processing chamber.

[0040] In at least some embodiments, the local controller 300 acts as a local EtherCAT master, and all matching network components, e.g., sensors, electromotive capacitors, are EtherCAT slave devices controlled by the local controller 300. For example, commands sent by the local controller 300 (e.g., an EtherCAT master controller) are passed to all EtherCAT slave devices. A first electromotive capacitor 302 (vacuum capacitor) with an EtherCAT interface may be connected to the local controller 300 and to a second electromotive capacitor 304 (vacuum capacitor) with an EtherCAT interface. The first electromotive capacitor 302 may be connected to the second electromotive capacitor 304 in a series or parallel configuration. For example, in the illustrated embodiment, the first electromotive capacitor 302 (e.g., a shunt variable capacitor) is connected in parallel with the second electromotive capacitor 304 (e.g., a series variable capacitor). The first electromotive capacitor 302 and the second electromotive capacitor 304 are electromotive variable capacitors and are configured to be adjusted during operation. For example, the local controller 300 can be configured to adjust the first electromotive capacitor 302 and the second electromotive capacitor 304 to minimize reflected power during plasma processing.

[0041] The local controller 300 may be connected (directly or indirectly) to a first sensor 306 disposed at the input of the matching network 188 and a second sensor 308 (when used) disposed at the output of the matching network 188 to obtain in-line RF voltage, current, phase, harmonic, and impedance data, respectively. In at least some embodiments, the first sensor 306 and the second sensor 308 may be multi-frequency voltage / current probes. The measured data may be used for automatic impedance tuning, load impedance monitoring, etc.

[0042] In at least some embodiments, an interlock circuit 307 may be connected to the local controller 300 and configured to prevent RF generator failure. For example, the interlock circuit 307 may include a fault protection circuit configured to stop RF power output from the RF generator when the reflected RF power exceeds a certain percentage (e.g., >20%) of the forward power, which is the RF power delivered by the RF generator through the matching network 188 to a load, e.g., a plasma in a processing chamber.

[0043] As described above, the EtherCAT communication interface connects the local controller 300 to the first electromotive capacitor 302, the second electromotive capacitor 304, the first sensor 306, and the second sensor 308. The EtherCAT communication interface directly connects an RF generator (e.g., RF bias power supplies 184, 186 (and / or bias power 189)) to each of the first sensor 306 and the second sensor 308, for example, for fast response and short adjustment time, to transmit a TTL signal 305 from the RF generator to each of the first sensor 306 and the second sensor 308.

[0044] In at least some embodiments, when connected to the RF generator and to the plasma processing chamber, the local controller 300 is configured as an EtherCAT master device that controls and monitors local EtherCAT slave devices, such as sensors and stepper motors. The local controller 300 is also integrated with an EtherCAT slave controller, so that the local controller 300 can act as an EtherCAT slave device and the controller 150 operates as an EtherCAT master device. That is, the local controller 300 is configured to perform master-slave conversion with the controller 150. The tool controller may be implemented on an industrial computer and embedded with the required drivers. In such an embodiment, the local controller 300 may receive feedback requests from the controller 150 and provide feedback to the controller 150 during plasma processing. For example, the local controller 300 may receive in-line RF voltage, current, phase, harmonics, and impedance data acquired via the first sensor 306 and the second sensor 308. The sensor data and variable capacitor position are transmitted to the controller 150 and can be combined with other system processed data, such as forward and reflected power data from the RF bias power supplies 184 and 186, thus creating coordinated intelligent real-time control during operation.

[0045] The matching network 188 may comprise at least one of a first network port 310 (e.g., a dual RJ45 type port) configured to connect to the controller 150 and a second serial port configured to connect to an external computing device (e.g., a laptop or other suitable computing device) for manual control of the matching network 188. For example, in at least some embodiments, the controller 150 may connect to the first network port 310 of the matching network 188 for plasma process control. The local controller 300 may receive in-line RF voltage, current, phase, harmonics, and impedance data acquired via the first sensor 306 and the second sensor 308. The sensor data and the variable capacitor position may be transmitted to the controller 150 and combined with other system processing data, such as forward and reflected power data from the RF bias power supplies 184 and 186, thus creating a coordinated intelligent real-time control during operation. In at least some embodiments, the matching network 188 may include a second serial port 312 configured to connect to a computing device 314 for algorithm upload and for manual control of the matching network, for example, by using external software and application programming interfaces (APIs). In at least some embodiments, the external software and APIs may be uploaded, stored in memory 154, accessed by the controller 150, and / or in a memory (not shown) of the local controller 300. In at least some embodiments, sensor data may be obtained from the first sensor 306 and the second sensor 308, and may be accessed from the computing device 314. Additionally, when connected to the second serial port 312, the computing device 314 may be configured to control the first electromotive capacitor 302 and the second electromotive capacitor 304.Providing the first network port 310 and the second serial port 312 provides the matching network 188 with greater flexibility compared to conventional matching networks. For example, advanced process related control algorithms can be deployed in real time, and the matching network 188 can operate fully autonomously, in cooperation with the controller 150, and / or manually controlled via the computing device 314. During processing, if necessary, the EtherCAT-based distributed RF impedance matching network described herein allows a user using the computing device 314 to have full control over the matching network 188 and its associated components.

[0046] 4 is a graph 400 of sampled impedance according to at least some embodiments of the present disclosure. For example, in at least some embodiments, a voltage waveform or RF power pulse applied at a substrate (e.g., substrate 103) in process chamber 100 may include two stages. The plasma sheath impedance varies with the applied pulse voltage waveform and RF power pulse, and matching network 188 monitors a TTL sync signal from the waveform generator 202 or RF power supply. For example, in a pulse cycle, two or more pulse data points may be collected by matching network 188 to collect impedance at different stages. In at least some embodiments, a first data sample is generated for impedance Z 1 In a first stage (e.g., at 404, which may correspond to a sheath collapse stage) for 2The weighted impedance value may be obtained by collecting data samples at a second stage (e.g., at 402, which may correspond to an ion current stage) for the impedance measurement. The collected data samples may be used to obtain a weighted impedance value. In at least some embodiments, the data samples need to be collected after a time delay, defined, for example, based on a pulsed frequency, duty cycle, and / or rising edge of the TTL synchronization signal.

[0047] In at least some embodiments, a high voltage DC power supply 208 may be used to supply power to the electrode 180 to chuck the substrate (e.g., wafer) during processing for temperature control. In at least some embodiments, a third electrode (not shown) may be provided at the edge of the cathode assembly for edge uniformity control. In such embodiments, a third low frequency RF power supply in the frequency range of 50 kHz to 2 MHz may be delivered to the edge electrode and operated in a continuous mode.

[0048] 5 is a diagram of a system 500, in accordance with at least some embodiments of the present disclosure. System 500 is substantially equivalent to system 200. Thus, only features unique to system 500 will be described herein.

[0049] For example, one or more RF power supplies (e.g., RF source power 143) are connected to the top electrode for plasma generation. The frequency of the one or more RF power supplies can be operated at a frequency of about 13.56 MHz to about 200 MHz, such as 60 MHz, 120 MHz, or 162 MHz, as required. The one or more RF power supplies can be operated in a continuous mode or a pulsed mode. The pulsed frequency can be from 100 Hz to 10 kHz, and the duty cycle can be from about 5% to about 95%. An RF bias power (e.g., RF bias power supply 184) is connected to the bottom electrode with a frequency range of about 100 kHz to about 15 MHz. The RF bias power can be operated in either a continuous mode or a pulsed mode. The pulsed frequency can be from 100 Hz to 10 kHz, and the duty cycle can be from about 5% to about 95%. One or both of the RF source power 143 and the RF bias power can be configured to send a synchronization TTL signal to the matching network 141 and the matching network 188, respectively. As mentioned above, a third electrode may be used at the edge of the cathode assembly for edge uniformity control. In such an embodiment, a third low frequency RF power supply in the frequency range of 50 kHz to 2 MHz may be delivered to the edge electrode and operated in a continuous mode. Similar to system 200, an RF filter may be connected (not shown) to matching network 188, and to matching network 141 and high voltage DC power supply 208. In at least some embodiments, an RF filter may be connected to matching network 188.

[0050] FIG. 6 is a diagram 600 of internal synchronization for dual-level pulsing, according to at least some embodiments of the present disclosure. For example, as described above, a trigger signal may be generated externally (e.g., via one or more RF power supplies or advanced waveform generators) or internally (e.g., via a matching network) to obtain impedance values ​​for determining the weighted average. In the latter embodiment, the voltage and current sensors (e.g., the first sensor 306 and the second sensor 308) of the matching network are configured to internally detect the start of the pulse signal. The voltage and current sensors may sense multiple impedance samples during the pulse cycle. For example, at a first sample time and at a second sample time defined relative to the start of the trigger signal, typically the rising edge of the pulse. Multiple impedances may be measured at the same pulse level or different levels and used in the weighted average tuning algorithm. Thus, the matching network uses weighted impedances from all measured samples at the same pulse level or different levels.

[0051] The collected data samples may be measured at a pulse or averaged from multiple pulses, for example, a threshold 601 may be defined for pulse detection. The threshold 601 may be set between two pulse state levels. The start of the pulse is detected when the voltage measured by a sensor (not shown) rises above the threshold 601. In at least some embodiments, sample 1 and sample 2 may be taken from different pulses. In at least some embodiments, sample 1 and sample 2 may be an average of many pulse data points collected from multiple pulses. For example, in at least some embodiments for calculating an averaged value, the pulse high state may be measured 10 times in 10 pulses to obtain averaged sample 1, and the pulse low state may be measured 10 times in the same or different 10 pulses to obtain averaged sample 2. The data point measurements are triggered after a delay of a first sample time and a second sample time relative to the start of the pulse. The first sample time and the second sample time determine when in the pulse the measurements are taken.

[0052] For example, a first data sample 602 and a second data sample 604 may be collected in a high state and a low state, respectively, by defining a first pulse time and a second pulse time relative to a trigger signal, e.g., a rising edge 606 of a pulse.

[0053] The inventors have discovered that the plasma load impedance can vary with multi-level pulse conditions due to different power levels or combinations of RF power sources (e.g., RF bias power supply 184 and RF source power supply 143). Furthermore, conventional matching networks do not allow for tuning both impedances simultaneously because the vacuum capacitor motors typically used cannot respond (e.g., move) quickly enough in the pulse cycle.

[0054] Thus, the inventors have provided a weighted combination of impedances (e.g., various impedance samples acquired via either an external or internal trigger) for single level pulsing or multi-level pulsing. For example, in dual level pulsing, a first impedance Z 1 may be measured at a first sample time at a first pulse level, and a second impedance Z 2 may be measured at a second sample time at a second pulse level. The weighted target impedance may then be calculated using equation (1): Z w =Z 1 *w+Z 2 *(1-w), where w is between 0 and 1.........., (1) where w is a weight value between 0 and 1. In at least some embodiments, if more weight values ​​may be needed, a multi-state weighting algorithm may also be used. For example, w1 and w2 may be weight values ​​in a triple-level pulsing situation. In operation, the weighted target impedance of the matching network described herein changes with the weight value during a dual impedance state. For example, when w is equal to 0, the matching network is tuned to an impedance equal to a second level in the pulse, whereas when w is equal to 1, the matching network is tuned to an impedance equal to a first level.

[0055] In at least some embodiments, an optimized w value may be determined based on the minimum total reflected power for both states. For example, the reflected power used varies with the weight value in dual level pulsing. For example, the first level may have the minimum reflected power at w=1, and the second level may have the minimum reflected power at w=0. For example, when w=0.8, the total reflected power for both states is at the minimum. Other criteria may also be used to select the appropriate weight value.

[0056] Similarly, the matching network provides a measured and weighted output impedance in dual level pulsing. For example, the plasma load impedance may vary with pulsed power level, bias power on and off, or pulse voltage waveform. Thus, Z 1 and Z 2 may be the measured impedance at the output of the matching network, again with either external or internal synchronization. As mentioned above, because motors in conventional matching networks are not able to follow rapidly changing impedance conditions, a weighted output impedance may be calculated and used as the target plasma load impedance. For example, in at least some embodiments, the weighted impedance at the output of the matching network may be used in a feedforward tuning algorithm as a tuning goal.

[0057] In at least some embodiments, the weighted input impedance and the weighted output impedance may be stored in a look-up table (e.g., in memory 154) or a circuit model may be used to directly move the variable capacitor in the RF match to the target position. In some embodiments, a learning-based tuning algorithm may be employed to find the appropriate weighted target impedance at the RF match input and / or output.

[0058] 7 is a flowchart of a method 700 for processing a substrate in accordance with at least some embodiments of the present disclosure. For purposes of illustration, the method 700 is described herein using the processing chamber 100 for etching the substrate 103.

[0059] At 702, the method 700 includes measuring an impedance at an input of a matching network configured to receive one or more radio frequency (RF) signals and at an output of the matching network configured to deliver one or more RF signals to a process chamber. For example, in at least some embodiments, at 702, the first sensor 306 may be configured to measure an impedance at an input of the matching network 188 and the second sensor 308 may be configured to measure an impedance at an output of the matching network 188.

[0060] Next, at 704, the method 700 includes adjusting at least one capacitor of the matching network to a first target position based on the measured impedance, e.g., based on weighted output impedance values ​​measured in a pulsed state of the voltage waveform, and adjusting at least one variable capacitor to a second target position based on weighted input impedance values ​​measured in a pulsed state of the voltage waveform, e.g.

[0061] For example, a variable capacitor (e.g., the second electromotive capacitor 304) may be adjusted based on a weighted output impedance value measured in a pulsed state and a weighted input impedance value measured in a pulsed state. For example, the weighted output impedance value and the weighted input impedance value are calculated using equation (1), as described above. In at least some embodiments, the at least one capacitor may comprise two variable capacitors (e.g., the first electromotive capacitor 302 and the second electromotive capacitor 304). In such embodiments, the at least two variable capacitors may be adjusted simultaneously or at different times.

[0062] In at least some embodiments, such as when the second sensor 308 is not used, the variable capacitor may be adjusted based on a weighted output impedance stored in a look-up table or circuit model (e.g., in memory 154).

[0063] In at least some embodiments (e.g., in an RF signal provided by an RF bias power supply, an RF signal provided by an RF source power, and / or a single-level pulsed signal configuration comprising a pulsed voltage waveform), the impedance value used for equation (1) may be obtained from a pulse-on state. Additionally, the first sample time and the second sample time may be the same or different and are based on at least one of a pulse frequency, a duty cycle, or a rising edge of a transistor-transistor logic (TTL) synchronization signal.

[0064] Similarly, in at least some embodiments (e.g., in a dual-level pulse signal configuration comprising at least one of an RF signal provided by an RF bias power supply, an RF signal provided by an RF source power, and / or a pulse voltage waveform), the impedance values ​​used for equation (1) may be obtained at a high-level pulse stage and a low-level pulse stage. In such embodiments, the high-level pulse stage is obtained at a first sample time and the low-level pulse stage is obtained at a second sample time that is different from the first sample time. Furthermore, the first sample time and the second sample time are triggered after a delay from the start of the pulse detected when the measured voltage of the pulse is equal to or greater than a threshold value.

[0065] A weighted impedance value may be calculated using equation (1) and the impedance data obtained for the single level pulse signal configuration, the dual level pulse signal configuration, or the multi-level pulse signal configuration. The calculated weighted impedance value is stored in memory 154 and is automatically accessed by controller 150 during operation at 704 to tune the first variable capacitor and / or the second variable capacitor to the weighted target impedance value.

[0066] While the forgoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof.

Claims

1. 1. A matching network configured for use with a plasma processing chamber, comprising: an input configured to receive one or more radio frequency (RF) signals; an output configured to deliver the one or more RF signals to a processing chamber; a first sensor operably connected to the input and a second sensor operably connected to the output and configured to measure impedance during operation; at least one variable capacitor coupled to the first sensor and the second sensor; a controller configured based on the measured impedance to adjust the at least one variable capacitor of the matching network to a first target position based on weighted output impedance values ​​measured during a pulsed state and to adjust the at least one variable capacitor to a second target position based on weighted input impedance values ​​measured during the pulsed state; A matching network comprising:

2. The weighted output impedance value and the weighted input impedance value are calculated using the following formula: Z ｗ =Z １ *w+Z ２ *(1-w)、 Here, Z １ is measured at time 1 and pulse level 1, and Z ２ 2. The matching network of claim 1 , wherein: ω is measured at time 2 and pulse level 2, where w is a weight value between 0 and 1.

3. 2. The matching network of claim 1, in a single level pulse signal configuration comprising an RF signal provided by an RF bias power supply, the pulse states corresponding to pulse data points collected to obtain impedance at a first data sample and at a second data sample of a pulse.

4. the first data sample is taken at a first time and the second data sample is taken at a second time different from the first time; 4. The matching network of claim 3, wherein the first time and the second time are based on at least one of a pulse frequency, a duty cycle, or a rising edge of a transistor-transistor logic (TTL) synchronization signal.

5. 2. The matching network of claim 1, in a dual level pulse signal configuration comprising at least one of an RF signal provided by an RF bias power supply or an RF signal provided by an RF source power, wherein the pulse states correspond to pulse data points collected to obtain impedance at a high level pulse stage and a low level pulse stage.

6. the high level pulse stage is taken at a first time and the low level pulse stage is taken at a second time different from the first time; 6. The matching network of claim 5, wherein the first time and the second time are triggered after a delay from the start of a detected pulse when a measured voltage is equal to or greater than a threshold value.

7. 2. The matching network of claim 1, wherein the matching network is connected to an RF bias power supply operable at a frequency of about 100 kHz, 13.56 MHz, 15 MHz, 60 MHz, 120 MHz or 162 MHz and in at least one of a continuous mode or a pulsed mode, wherein in the pulsed mode, the pulse frequency is from about 100 Hz to about 10 kHz and the duty cycle is from about 5% to about 95%.

8. 2. The matching network of claim 1, wherein the matching network is connected to an RF source power operable at a frequency of about 13.56 MHz, 60 MHz, 120 MHz, 162 MHz, or 200 MHz and in at least one of a continuous mode or a pulsed mode, wherein in the pulsed mode, the pulse frequency is from about 100 Hz to about 10 kHz and the duty cycle is from about 5% to about 95%.

9. The matching network of claim 1 , wherein the at least one variable capacitor comprises a series variable capacitor and a shunt variable capacitor.

10. 1. A plasma processing chamber comprising: a chamber body and a chamber lid; an RF power source connected to the chamber lid and configured to create a plasma from a gas disposed in a processing region of the chamber body; one or more RF bias power sources configured to sustain a plasma discharge; Matching network and said matching network comprising: an input configured to receive one or more radio frequency (RF) signals; an output configured to deliver the one or more RF signals to a processing chamber; a first sensor operably connected to the input and a second sensor operably connected to the output and configured to measure impedance during operation; at least one variable capacitor coupled to the first sensor and the second sensor; a controller configured based on the measured impedance to adjust the at least one variable capacitor of the matching network to a first target position based on weighted output impedance values ​​measured during a pulsed state and to adjust the at least one variable capacitor to a second target position based on weighted input impedance values ​​measured during the pulsed state; A plasma processing chamber comprising:

11. The weighted output impedance value and the weighted input impedance value are calculated using the following formula: Z ｗ =Z １ *w+Z ２ *(1-w)、 Here, Z １ is measured at time 1 and pulse level 1, and Z ２ 11. The plasma processing chamber of claim 10, wherein: is measured at time 2 and pulse level 2, where w is a weighting value between 0 and 1.

12. 11. The plasma processing chamber of claim 10, wherein in a single level pulse signal configuration comprising an RF signal provided by an RF bias power supply, the pulse states correspond to pulse data points collected to obtain impedance at a first data sample and at a second data sample of a pulse.

13. the first data sample is taken at a first time and the second data sample is taken at a second time different from the first time; 13. The plasma processing chamber of claim 12, wherein the first time and the second time are based on at least one of a pulse frequency, a duty cycle, or a rising edge of a transistor-transistor logic (TTL) synchronization signal.

14. 11. The plasma processing chamber of claim 10, wherein in a dual level pulse signal configuration comprising at least one of an RF signal provided by an RF bias power supply or an RF signal provided by an RF source power, the pulse states correspond to pulse data points collected to obtain impedance at a high level pulse stage and a low level pulse stage.

15. the high level pulse stage is taken at a first time and the low level pulse stage is taken at a second time different from the first time; 15. The plasma processing chamber of claim 14, wherein the first time and the second time are triggered after a delay from a start of a pulse that is detected when a measured voltage is equal to or greater than a threshold value.

16. 11. The plasma processing chamber of claim 10, wherein the matching network is connected to an RF bias power supply operable at a frequency of about 100 kHz, 13.56 MHz, 15 MHz, 60 MHz, 120 MHz or 162 MHz and in at least one of a continuous mode or a pulsed mode, wherein in the pulsed mode, the pulse frequency is from about 100 Hz to about 10 kHz and the duty cycle is from about 5% to about 95%.

17. 11. The plasma processing chamber of claim 10, wherein the matching network is connected to an RF source power operable at a frequency of about 13.56 MHz, 60 MHz, 120 MHz, 162 MHz, or 200 MHz and in at least one of a continuous mode or a pulsed mode, wherein in the pulsed mode, the pulse frequency is from about 100 Hz to about 10 kHz and the duty cycle is from about 5% to about 95%.

18. The plasma processing chamber of claim 10 , wherein the at least one variable capacitor comprises a series variable capacitor and a shunt variable capacitor.

19. 1. A method for processing a substrate, comprising: Measuring impedance at an input of a matching network configured to receive one or more radio frequency (RF) signals and at an output of the matching network configured to deliver the one or more rf signals to a process chamber; adjusting the at least one variable capacitor of the matching network to a first target position based on weighted output impedance values ​​measured during a pulsed state based on the measured impedance, and adjusting the at least one variable capacitor to a second target position based on weighted input impedance values ​​measured during the pulsed state based on the measured impedance. A method comprising:

20. The weighted output impedance value and the weighted input impedance value are calculated using the following formula: Z ｗ =Z １ *w+Z ２ *(1-w)、 Here, Z １ is measured at time 1 and pulse level 1, and Z ２ 20. The method of claim 19, wherein: is measured at time 2 and pulse level 2, where w is a weight value between 0 and 1.

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