Cost-effective high-frequency impedance matching network

Abstract

Embodiments provided herein generally include an apparatus and method in a plasma processing system for fast and inexpensive repair and replacement of radio frequency (RF) sensors required for operation of RF power generation and impedance matching equipment used to generate plasma in a plasma chamber during semiconductor processing in the plasma chamber. Flexible communication between the equipment in this plasma processing system enables sharing of process information and equipment settings for batch processing of multiple semiconductor wafers during a manufacturing process. Operational settings of a master plasma processing system can be used to control the operation of multiple slave processing systems. Additionally, operational settings of the master plasma processing system can be recorded and reused to control multiple slave processing systems.

Description

[Background technology]

[0001] Technical Field Embodiments of the present disclosure generally relate to high-power radio frequency (RF) power sources and impedance matching networks adapted for generating plasma in semiconductor processing reactor chambers, and more particularly to cost-effective RF impedance matching networks and associated subassemblies of RF impedance matching networks.

[0002] 2. Description of Related Art In a plasma reactor chamber, an RF power source provides RF power to the plasma reactor chamber to generate plasma in the plasma reactor chamber through an impedance matching network coupled between the RF power source and the plasma reactor chamber. The RF impedance of the plasma is a complex and highly variable function of many process parameters and conditions. The impedance matching network maximizes power transfer from the RF power source to the plasma in the reactor chamber. This is achieved when the output impedance of the impedance matching network is equal to the complex conjugate of the input impedance of the plasma in the reactor chamber. The impedance matching network transforms the impedance of the plasma in the reactor chamber to the characteristic operating output impedance of the RF power source, e.g., 50 ohms, for optimal RF power transfer from the RF power source.

[0003] An RF impedance matching network is an electrical circuit disposed between an RF power source and a plasma reactor to optimize RF power transfer efficiency. To optimize RF power transfer, it is important that the RF impedance matching network be accurately tuned to the desired complex impedance at the desired frequency. This is crucial for providing reliable, efficient, and predictable plasma process results. To ensure operational accuracy, the RF impedance matching network relies on the accuracy of associated RF sensors, such as RF voltage, RF current, and RF power sensors, used to provide real-time plasma processing conditions, e.g., plasma chamber impedance and RF power supplied to the plasma chamber during semiconductor manufacturing process operation. However, maintaining the operation and accuracy of plasma chamber RF sensors can be very time-consuming and labor-intensive, resulting in costly semiconductor process downtime.

[0004] Therefore, there is a need for lower cost, faster repair, calibration, and / or replacement of RF sensors to maintain longer operating times of RF sources and RF impedance matching networks, and thereby increased plasma chamber processing utilization. Summary of the Invention

[0005] An embodiment of the present disclosure includes a radio frequency (RF) impedance matching unit adapted for coupling between an RF power generator and a plasma processing chamber. The RF impedance matching unit includes an RF tuning circuit having a first node adapted for coupling to the RF power generator, a second node adapted for coupling to the plasma processing chamber, and an adjustable tuning element for transforming an output resistance of the RF power generator into a plurality of impedances at the second node. The RF impedance matching unit further includes a match controller coupled to the adjustable tuning element of the RF tuning circuit, the match controller controlling and monitoring a position of the adjustable tuning element of the RF tuning circuit, and a communication interface coupled to the match controller for receiving position information and transmitting position information to the adjustable tuning element of the RF tuning circuit.

[0006] An embodiment of the present disclosure includes a system for controlling and monitoring a radio frequency (RF) power generator and an impedance matching unit adapted to generate plasma in a plasma processing chamber. The RF power generator has an RF output and is coupled to a first communication interface for monitoring and controlling the RF power generator. An RF power measurement module is coupled to the output of the RF power generator to measure forward and reflected RF power at the output of the RF power generator and calculate a standing wave ratio (SWR) from the measured forward and reflected RF power. A second communication interface is coupled to the RF power measurement module for transmitting the measured forward and reflected RF power and the calculated SWR. An RF tuning circuit has a first node coupled to the RF power measurement module and an adjustable tuning element for converting the output resistance of the RF power generator into multiple impedances at a second node of the RF tuning circuit. A match controller is coupled to the adjustable tuning element of the RF tuning circuit, and the match controller controls and monitors the position of the adjustable tuning element of the RF tuning circuit. A third communication interface is coupled to the match controller for receiving and transmitting position information of the adjustable tuning element of the RF tuning circuit. An RF impedance measurement module is coupled between a second node of the RF tuning circuit and the plasma processing chamber, and measures an RF voltage, an RF current, and a frequency at the second node of the RF tuning circuit, determines an RF phase from the measured RF voltage and RF current, and calculates an RF impedance at the second node from the measured RF voltage, RF current, RF phase, and frequency. A fourth communication interface is coupled to the RF impedance measurement module for transmitting the measured RF voltage, RF current, RF phase, frequency, and calculated impedance at the second node. A tool controller is adapted to control the RF power output of the RF power generator and to instruct the match controller using process recipe tuning element settings when generating the plasma. A fifth communication interface is coupled to the tool controller.At least two of the first communication interface, the second communication interface, the third communication interface, the fourth communication interface, and the fifth communication interface communicate with each other during an operation to generate a plasma in the plasma processing chamber.

[0007] An embodiment of the present disclosure includes a method for group processing of multiple semiconductor wafers using multiple plasma processing systems by providing a master plasma processing system comprising: a master radio frequency (RF) power generator; a master impedance matching unit having a first node coupled to the master RF power generator and a second node adapted for coupling to a master plasma processing chamber, the master impedance matching unit further comprising a master RF tuning circuit having an adjustable tuning element; and a communication interface coupled to the master RF power generator and the master impedance matching unit, each of the multiple slave plasma processing systems comprising: a slave RF power generator; a slave impedance matching unit having a first node coupled to the slave RF power generator and a second node adapted for coupling to the slave plasma processing chamber, the slave impedance matching unit further comprising a slave RF tuning circuit having an adjustable tuning element; and a communication interface coupled to the slave RF power generator and the slave impedance matching unit. The method further provides for reading a master power setting of the master RF power generator during the master plasma processing operation and communicating the master power setting to each of the slave RF power generators, wherein each of the slave RF power generators operates at the master power setting during the slave plasma processing operation; and reading a master position setting of an adjustable tuning element of the master RF tuning circuit during the master plasma processing operation and communicating the master position setting to each of the slave impedance matching units, wherein each of the adjustable tuning elements of the slave impedance matching units operates at the same position setting of the adjustable tuning element of the master RF tuning circuit during the slave plasma processing operation.The method further provides for recording the master power setting and the master position setting of the adjustable tuning element prior to communicating the master power setting and the master position setting to the slave RF power generator and the slave impedance matching unit.

[0008] So that the above-recited features of the present disclosure may be better understood in detail, a more particular description of the present disclosure, briefly summarized herein, may be made by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only exemplary embodiments and therefore should not be considered limiting of its scope, as other equally effective embodiments may be recognized. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 illustrates a schematic block diagram of a semiconductor wafer plasma processing system having a field replaceable sensor module, in accordance with certain exemplary embodiments of the present disclosure. [Figure 2] FIG. 1 illustrates a schematic block diagram of a semiconductor wafer plasma processing system having a field-replaceable external quick connect sensor module, in accordance with certain exemplary embodiments of the present disclosure. [Figure 3] FIG. 1 illustrates a schematic block diagram of an RF impedance measurement module, in accordance with certain exemplary embodiments of the present disclosure. [Figure 4] FIG. 1 illustrates a schematic block diagram of an RF RF power measurement module, in accordance with certain exemplary embodiments of the present disclosure. [Figures 5A-5C] FIG. 1 illustrates a schematic diagram of an RF tuning circuit, in accordance with certain exemplary embodiments of the present disclosure. [Figure 6] FIG. 1 illustrates a schematic block diagram of a match controller, in accordance with certain exemplary embodiments of the present disclosure. [Figure 7] 1 is a schematic view of a plasma processing chamber having two impedance matching units, in accordance with certain exemplary embodiments of the present disclosure. [Figure 8] 1 is a schematic view of a plasma processing chamber having one impedance matching unit controlled by a remote sensor, in accordance with certain exemplary embodiments of the present disclosure. [Figure 9] FIG. 1 illustrates a schematic block diagram of a slave semiconductor wafer plasma processing system, in accordance with certain exemplary embodiments of the present disclosure. [Figure 10] FIG. 1 illustrates a schematic block diagram of a multiple semiconductor wafer plasma processing system having one master plasma processing subsystem and multiple slave plasma processing subsystems, in accordance with certain exemplary embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] For ease of understanding, like reference numerals have been used, where possible, to designate like elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0011] FIELD OF THE DISCLOSURE Embodiments of the present disclosure generally relate to apparatus and methods for rapid, inexpensive defect analysis, repair, and replacement of equipment used in the manufacture of semiconductor devices. More particularly, embodiments provided herein generally include apparatus and methods for rapid, inexpensive repair and replacement of radio frequency (RF) sensors required for the operation of RF power generation and impedance matching equipment used to generate plasma in a plasma chamber during semiconductor processing in the plasma chamber.

[0012] Embodiments of the present disclosure relate to input and output process sensors, e.g., RF voltage and current, frequency, and RF power, that may be independent of an associated RF impedance matching unit in a plasma processing system and may be replaced upon failure or for periodic recalibration without disturbing or disassembling other parts of the plasma processing system. The sensors may be internal or external to the RF impedance matching unit structure, adapted for quick connection and disconnection, and have RF power and communication connectors (used for monitoring and control) that may be replaceable and reusable for design and operational scalability; for example, sensor modules may be swapped for periodic recalibration to ensure accuracy, resulting in reduced long-term operation and maintenance costs.

[0013] Process sensors can be configured into independent, autonomous modules with application-specific sensor interfaces, data processing, calculations, and control. Independent module communication uses a fast, secure communication protocol that provides global communication between modules, tool controllers, and monitoring systems. Communication can be provided using industrial-quality software protocols, such as, but not limited to, Ethernet for Control Automation Technology (EtherCAT or ECAT). EtherCAT communication enables quick and easy module and system updates and maintenance in the field, as well as efficient in-process testing and qualification of manufacturing systems. Testing, qualification, and firmware / software updates of sensor and controller modules can be performed remotely using Failover EtherCAT (FoE), which can reduce maintenance, calibration, and logistics costs. Each EtherCat communication interface has a unique address and can be adapted to communicate sensor and control data to other EtherCat communication interfaces, thereby making all process information available to all modules in the system.

[0014] RF impedance and RF power sensor information from independent RF impedance and power modules can be shared throughout the plasma processing system for diagnostic purposes and algorithm pre-training. Modules providing sensor information can be reusable for impedance matching unit design scalability. Sensor modules can be adapted for use with other impedance matching units and / or operate at other RF frequencies and load impedances. Each sensor module can have a unique communication address and be accessible, with its data available for process data logging in all other plasma processing system modules, controllers, and production monitoring systems.

[0015] In another embodiment of a plasma processing system including multiple plasma processing chambers, each chamber having a slave RF generator and a slave impedance matching unit, one set of process sensor modules may be used to control the operation of the slave RF generators and slave impedance matching units associated with the multiple plasma processing chambers. If the chambers and plasma processes are substantially the same, sensor information from only one process chamber may be needed, and the operation of the associated slave RF generators and impedance matching units of the other process chambers may be controlled by the lead or master process chamber / sensor module information (process data). This synchronization between multiple ongoing plasma processes may also be shared for diagnostic purposes and algorithm pre-training.

[0016] In some embodiments, sensor data of the plasma process can be used and recorded for learning purposes, and then the sensor can be disconnected and the recorded learning process data can be used in place of the sensor data. Process control settings, such as impedance matching element setting positions and RF power process levels, can be stored in the tool controller and then used by the tool controller for multiple different process recipes. This allows a well-established and consistent manufacturing process to be implemented without the need for sensor monitoring of the manufacturing process. This is especially advantageous for the multiple chamber plasma processes that occur during a semiconductor device manufacturing day. The same process recipe does not need to be applied to all of the plasma processing systems at the same time. Different plasma processing recipes can be distributed among manufacturing plasma chamber systems depending on the manufacturing requirements for different semiconductor products.

[0017] Referring now to the drawings, details of exemplary embodiments are generally illustrated, in which like elements are represented by like numbers and similar elements are represented by like numbers with different lower case suffixes.

[0018] Referring to FIG. 1 , a schematic block diagram of a semiconductor wafer plasma processing system is depicted in accordance with certain exemplary embodiments of the present disclosure. The plasma processing system, generally designated by the numeral 100, may include a plasma chamber 102 for processing semiconductor wafers therein, an RF impedance matching unit 104, an RF power generator 106, a tool controller 108, and a user interface 110. The RF impedance matching unit 104, the RF power generator 106, the tool controller 108, and the user interface 110 may communicate, control, and monitor the delivery of RF power to the plasma chamber during processing using protocols such as, but not limited to, Ethernet for control automation technology (EtherCAT or ECAT), USB, serial RS-232, Ethernet, WiFi, and Bluetooth. For purposes of discussion herein, the primary means of communication, control, and monitoring used will be EtherCAT. “EtherCAT” or “ECAT” is a high-performance, low-cost, and easy-to-use industrial Ethernet technology with a flexible topology. Further information about EtherCat can be found at the EtherCat technology website https: / / www.ethercat.org, which is incorporated herein by reference for all purposes. EtherCat uses Ethernet packet-based communications, but is much faster and more robust than typical Ethernet systems and other similar communications protocols. EtherCat is particularly applicable to industrial manufacturing processes that require a high degree of security and reliability while maintaining high data and control throughput in real time.

[0019] Flexibility, compatibility, reliability, and rapid repair and replacement of defective modules are addressed in the embodiments disclosed herein. Allowing subsystems, e.g., equipment modules, to be field replaceable without requiring special installation and calibration procedures allows for increased manufacturing uptime and reduced overall system maintenance and manufacturing costs. Standardization and interoperability among subsystems also reduces equipment costs and improves ease of maintenance of equipment so designed and deployed.

[0020] The impedance matching unit 104 may include an RF tuning circuit 112, a match controller 114 for controlling the RF integrated circuit 112, a memory 116 coupled to the match controller 114, a safety and operational interlock 118, an RF power measurement module 120 having an input coupled to the output of the RF power generator 106, an RF filter 122 coupled between the RF power measurement module 120 and the input of the RF tuning circuit 112, another RF filter 122a coupled to the output of the RF tuning circuit 112, an RF impedance measurement module 124, and a temperature sensor 126. The match controller 114 may include a communication interface adapted for a communication protocol such as, but not limited to, EtherCat (ECAT) communication. The match controller 114 may be an ECAT master or a slave; when the tool controller 108 is the ECAT master, the match controller 114 is an ECAT slave of the outer control loop. On the other hand, the match controller 114 is the ECAT master of the inner control loop, while the variable capacitors in the RF tuning circuit 112, RF sensor modules 120 and / or 124 can be ECAT slaves. All of the above-mentioned modules are accessible for monitoring and control through EtherCat (ECAT) communication.

[0021] The user interface 110, e.g., a computer (laptop computer), may communicate with the tool controller 108 (EtherCat master) using a USB to EtherCat adapter 128, or may be coupled to the tool controller 108 using RS-232, WiFi, or other standard communication protocols (not shown). This communication link may give the user interface 110 access to all sensor information and control of the plasma processing system 100, e.g., via EtherCat communications coupled to each subsystem of the plasma processing system 100. RF power from the RF power generator 106 may be coupled to the RF power measurement module 120 via a power supply line 130, e.g., a coaxial cable type LMR-600, TRU-500, or the like, and RF power from the impedance matching unit 104 may be coupled to an RF coil (not shown) of the plasma chamber 102 via a power supply line 130a. It is contemplated and within the scope of this disclosure that the electrical conductors used to supply RF power between the module and the plasma chamber 102 may include, but are not limited to, (a) a coaxial cable or a combination of coaxial cables, such as a flexible coaxial cable connected in series with a rigid coaxial cable, (b) an insulated high voltage corona resistant hook-up wire, (c) bare wire, (d) a metal rod, (e) an electrical connector, or (f) any combination of the electrical conductors / cables in (a)-(e).

[0022] 2, a schematic block diagram of a semiconductor wafer plasma processing system having a field-replaceable external quick-connect sensor module is depicted in accordance with certain exemplary embodiments of the present disclosure. The plasma processing system, generally designated by the numeral 200, may include a plasma chamber 102 for processing semiconductor wafers therein, an RF impedance matching unit 204, an RF power generator 106, a tool controller 108, and a user interface 110. The RF impedance matching unit 204, the RF power generator 106, the tool controller 108, and the user interface 110 may communicate, control, and monitor using the protocols described for the semiconductor wafer plasma processing system 100 described above.

[0023] Impedance matching unit 204 is substantially similar to impedance matching unit 104 described above, except that at least one RF measurement module, e.g., RF impedance measurement module 224, in this embodiment, is external to the housing of impedance matching unit 204 and is coupled to RF filter 122a using a quick-connect coaxial connector 232, e.g., but not limited to, a flangeless coaxial connector available from Myat Corporation at www.myat.com. Functionally, plasma processing system 200 functions similarly to plasma processing system 100 shown in FIG. 1, but with an external RF measurement module, e.g., RF impedance measurement module 224, that can be easily removed and replaced with a replacement module without disturbing other components or having to disassemble impedance matching unit 204 in the field. The only operations required for field replacement of a defective RF impedance measurement module 224 are to disconnect the coaxial cables 230a and 230b from the coaxial connectors 232a and 232b and from the EtherCat communication cable, respectively, then replace the defective impedance measurement unit 204 with a functional one, reconnect the coaxial cables 230a and 230b to the coaxial connectors 232a and 232b, and reconnect the EtherCat communication / power cable (EtherCat-P). The impedance matching unit 204 can be configured so that either the RF measurement module and / or the RF filter are externally mounted for ease of field maintenance and / or replacement. The RF impedance measurement module 224 can be an ECAT slave that communicates with the tool controller 108 or the match controller 114.

[0024] High Frequency Impedance and Power Determination Radio frequency (RF) impedance is determined by the RF voltage V(t), RF current I(t), phase angle θ, and frequency of the RF waveform. RF voltage and current sensors measure the RF voltage V(t) and RF current I(t), and the phase angle θ is determined from the RF voltage V(t) and RF current I(t). Frequency is measured using a frequency detector. The phase angle is the lead or lag time between the RF voltage V(t) and RF current I(t) waveforms, expressed in degrees θ. RF power P(t) is the product of voltage and current, or P(t) = V(t) × I(t), while the root mean square (RMS) value of each after sensor detection is P = V × I × cosθ, where θ is the ratio of the voltage waveform to the is the phase angle between the current waveform. Using Ohm's Law, Z(t) = V(t) / I(t) or Z can be expressed as Z = R + jX, where R = Z cosθ and jX = Z sinθ. jX = jωL-j / ωC, where ω = 2πf, f is in frequency, C is in farads, and L is in henrys. R is the resistance in ohms, and jX is the reactance in ohms, where +jX is the inductive reactance and -jX is the capacitive reactance. Power is frequency independent, and impedance is frequency dependent.

[0025] 3, a schematic block diagram of an RF impedance measurement module is depicted in accordance with certain exemplary embodiments of the present disclosure. RF impedance measurement module 124 may include an RF current sensor 302, an RF voltage sensor 304, an RF frequency detector 306, an RF phase detector 308, a temperature sensor 310, a microcontroller 312 with memory 314 and digital signal processing (DSP) / fast Fourier transform (FFT) 316 capabilities, and an EtherCat communication interface 318. RF impedance measurement module 124 may further include a coaxial connector 320, which may be quick-connect and flangeless for ease of removal and installation of RF impedance measurement module 300 and EtherCat connectors 322a and 322b. RF coaxial connectors 320a and 320b may be bidirectional, such that either one may be used as an RF input and the other may be used as an RF output. The EtherCat communication interface 318 may be adapted for EtherCat-P, which may provide DC power to the electronic circuitry of the RF impedance measurement module 124 .

[0026] The RF current sensor 302 senses the RF current I(t), and the RF voltage sensor 304 senses the RF voltage V(t). The RF current I(t) and voltage V(t) are received by analog inputs of the microcontroller 312 and then converted to digital representations of the RF current I(t) and voltage V(t). The phase angle θ (the time difference between I(t) and V(t)) can be determined using the phase detector 308, or can be determined after I(t) and V(t) are converted to digital representations. In either case, the phase angle θ can be converted to digital format by the microcontroller 312. The RF frequency detector 306 provides frequency information to the microcontroller 312 in digital format, for example, from a time-based digital counter. Once the RF current, voltage, phase, and frequency are known, the impedance at the RF coaxial connector 320 and the RF power entering the load (plasma processing chamber) can be calculated as described above using the DSP / FFT 316 function of the microcontroller 312. The memory 314 may be adapted to store calculated real-time impedance and power, and may also be used to store calibration coefficients for the RF current and voltage sensors and frequency and phase detectors. The sensor, detector, impedance, and power information may also be presented in digital format from the microcontroller 312 to an EtherCat communication interface 318 for use (information and control) by the plasma processing system 100 and other subsystems of the plasma processing system 100.

[0027] High frequency forward and reverse power and voltage standing wave ratio Measurement of forward and reverse RF power is useful for maximizing the most efficient power transfer from the RF generator by adjusting the impedance matching network to match the RF generator's output impedance, typically 50 ohms, to the complex load impedance of the plasma processing chamber. Forward and reverse RF power sensors (detectors) are useful in obtaining information for adjusting the impedance matching network for maximum forward RF power acceptance and minimum reverse RF power returned to the RF generator. The forward and reverse power sensors can also be used to determine the standing wave ratio (SWR) along the transmission line from the output of the RF generator to the input of the matching network. Because the length of the transmission line (e.g., coaxial cable) between the RF generator and the impedance matching network is very short with respect to the wavelength of the RF signal from the RF generator, the length of the transmission line can be ignored, and as a result, the SWR is used as a measure of the match quality of the impedance matching network to the RF generator. Since the output of the RF generator is at a fixed impedance (e.g., 50 ohms), the SWR is usually thought of in terms of the maximum and minimum RF voltage along the transmission line (in this case, at the output of the RF generator), and is called the voltage standing wave ratio, or VSWR.

[0028] SWR can be determined from the effective forward and reflected voltages at the output of the RF generator for the characteristic impedance for which the SWR detector is designed. Because the power of the forward and reflected RF waves is proportional to the square of the voltage component due to each forward and reflected RF wave, SWR can be expressed in terms of forward and reflected power as follows, where Pf is the forward power and Pr is the reflected power: TIFF2025536234000002.tif19170

[0029] As noted above, measurements of forward and reflected RF power are not frequency dependent like measurements of RF impedance, but are based on a fixed, known resistance, e.g., 50 ohms, and thus SWR measurements are similarly not frequency dependent. However, to be accurate, SWR measurements must be taken at a known, fixed resistance, and for this reason, power and SWR measurements are made at the known, fixed resistance output of the RF generator and not used at the complex impedance load side of the impedance matching network on which RF voltage, current, and frequency sensors must be relied upon to determine the plasma process impedance.

[0030] 4, a schematic block diagram of an RF power measurement module is depicted in accordance with a specific exemplary embodiment of the present disclosure. RF power measurement module 120 may include a forward RF power sensor 402, a reflected RF power sensor 404, a temperature sensor 410, a microcontroller 412 with memory 414, and an EtherCat communication interface 418. RF power measurement module 120 may further include a coaxial connector 420, which may be quick-connect and flangeless for ease of removal and installation of RF power measurement module 120 and EtherCat connectors 422a and 422b. EtherCat communication interface 418 may be adapted for EtherCat-P, which may provide DC power to the electronics of RF power measurement module 120.

[0031] The forward RF power sensor 402 senses the RF power going to the input of the RF tuning unit 112, and the reflected RF power sensor 404 senses the RF power reflected back from the RF tuning unit 112. The SWR and reflected RF power may be used to verify proper operation of the RF tuning unit 112 and / or assist in the matching operation of the RF tuning unit 112 (e.g., adjust the RF tuning unit 112 for minimum SWR and / or reflected RF power). The forward and reflected RF power values ​​from the forward RF power sensor 402 and the reflected RF power sensor 404, respectively, may be received by analog inputs of the microcontroller 412 and then converted to digital representations of the forward and reflected RF power values. The SWR at the RF output coaxial connector 420b may be calculated from the forward and reflected RF power values, as described above. The forward and reflected power and SWR information may be presented in digital format from the microcontroller 412 to the EtherCat communication interface 418 for use (information and control) by the plasma processing system 100 and other subsystems of the plasma processing system 100, such as the match controller 114.

[0032] Impedance Matching Unit Control and Tuning 5A, 5B, and 5C, schematic diagrams of RF tuning circuits are depicted in accordance with certain exemplary embodiments of the present disclosure. FIGS. 5A and 5B show three variable capacitors VC1, VC2, and VC3, and FIG. 5C shows two variable capacitors VC1 and VC3, e.g., motor-driven vacuum variable capacitors, in combination with inductor L1 (and L2) for RF tuning circuit 112. Variable capacitors VC1, VC2, and VC3 may have a capacitive range, but not limited to, from about 3 pF to about 5000 pF. L1 is an inductor and may have an inductive range, but not limited to, from about 0.01 μH to about 1000 μH. VC3 may be used to adjust a target frequency from about 100 kHz to about 250 MHz, and VC1 and VC2 may be used to tune to a target impedance. In some embodiments, particularly for complex loads at low frequencies, the schematic configuration of the RF circuit shown in FIG. 5B may be implemented. An additional inductor L2 may be added to tune the RF tuning circuit 112 to a desired value. The inductor L2 may be in the range of, but is not limited to, approximately 0.01 μH to approximately 1000 μH. A low-pass Pi matching circuit is shown in FIGS. 5A and 5B. In some embodiments, the RF tuning circuit 112 may be an L-type circuit shown in FIG. 5C that uses only two motor-driven vacuum variable capacitors, e.g., VC1 and VC3. The capacitance and / or inductance values ​​of the variable elements, e.g., VC1, VC2, and VC3, may be controlled and monitored by a position control and monitoring circuit 502 for each variable element (one shown). Additional capacitors and / or inductors may also be switched into the matching circuit as needed (not shown). The motor position actuator of the position control and monitoring circuit 502 may also include a position sensor that indicates the mechanical position of an adjustable element, for example, the amount of shaft rotation of a variable vacuum capacitor or a synchronous stepper motor position count after the minimum and maximum rotational positions have been determined (detection of maximum and minimum clockwise and counterclockwise shaft rotation).The position values ​​may be correlated in a capacitance (or inductance)-position value table, so that capacitance and / or inductance values ​​may be monitored and set to desired positions based on the required capacitance / inductance values. The tuning element position values ​​may be used to monitor and pre-set tuning element positions in accordance with the teachings of the present disclosure.

[0033] Referring to FIG. 6, a schematic block diagram of a match controller is depicted in accordance with certain exemplary embodiments of the present disclosure. The match controller 114 may monitor and control variable elements (e.g., variable capacitors V, V, and V) of the RF tuning circuit 112. The match controller 114 may include a microcontroller 612, memory (volatile and / or non-volatile) 614, stepper motor drivers and position sensors 502 (FIG. 5), and an EtherCat communication interface 618. Via EtherCat communication, the microcontroller 612 may receive plasma chamber impedance information from the associated RF impedance measurement module 124 or 224 and / or RF power measurement module 120. This impedance information then controls the positions of the variable elements (e.g., variable capacitors V, V, and V) of the RF tuning circuit 112 to complete an impedance match between the RF power generator 106 and the plasma chamber 102.

[0034] When in slave mode (FIGS. 9 and 10), the microcontroller 612 may receive positions of variable elements (e.g., variable capacitors VC1, VC2, and VC3) via EtherCat communication based on a substantially identical RF tuning circuit 112 of another plasma processing system 100 acting as a process master. This enables batch processing of the same semiconductor wafer workpiece using multiple substantially similar plasma processing systems slaved to a master plasma processing system (FIG. 10). Alternatively, in high-productivity, well-known plasma processes, the microcontroller 612 may receive positions of variable elements (e.g., variable capacitors VC1, VC2, and VC3) via EtherCat communication based on a pre-recorded process recipe. The process recipe, including the positions of the variable elements, may be stored in memory 614 to reduce EtherCat communication and microprocessor operation time. This allows the process to use process data stored in memory 614, with stored positions over the process time, for an autonomous plasma process that does not require external inputs.

[0035] Referring to FIG. 7, a schematic block diagram of a plasma processing chamber having two impedance matching units is depicted, in accordance with certain exemplary embodiments of the present disclosure. The plasma processing chamber 702 includes an RF electrode 772 and a workpiece pedestal 774. The RF electrode 772 is coupled to a first impedance matching unit 704, which receives RF power from an RF power generator 706. In one example, the RF electrode 772 may be a showerhead used to form a capacitively coupled plasma in the plasma processing chamber 702, or a multi-turn coil used to form an inductively coupled plasma in the plasma processing chamber 702. A second impedance matching unit 776 is coupled between the workpiece pedestal 774 and the RF power generator 778. A DC blocking capacitor 784 blocks high-voltage DC from a high-voltage power supply 780 and may also function as a high-pass filter.

[0036] Optionally, an RF impedance measurement module similar to sensor module 224 ( FIG. 2 ) may be at the output of match 776 and / or between pedestal 774 and second impedance match 776. It is contemplated and within the scope of the present disclosure that one or more sensor modules may be shared between the two impedance matching units 704 and 776. A sensor module may be used only for learning purposes and then removed. A sensor module may be adapted to form a virtual match group; for example, data measured at the output of impedance matching unit 776 may be used to control impedance matching unit 704. Sensor modules may also be added in other locations, such as the roof, liner, or baffle (not shown), and may provide measurements that may be used to adjust tuning element capacitors.

[0037] The electrical characteristics of the plasma formed through the use of the first impedance match unit 704, RF power generator 706, second impedance match unit 776, and RF power generator 778 can be monitored through the use of a sensor module 224 coupled to a node located between the embedded electrode 770 and the second impedance match 776 or between the first impedance match 704 and the RF electrode 772. Information from and control of these items can be processed in a tool controller 708 that communicates to each via individual EtherCat communication lines. The impedance match units 704 and 776 can be controlled by the tool controller 708 through communication via the EtherCat communication lines. Which sensor information is used to control which match unit simply depends on how the process is programmed, as all monitoring and control is available for all process system elements, e.g., sensors, match unit element tuning, RF power output.

[0038] Referring to FIG. 8 , a schematic block diagram of a plasma processing chamber having one impedance matching unit controlled by a remote sensor is depicted, in accordance with a specific exemplary embodiment of the present disclosure. The plasma processing chamber system depicted in FIG. 8 is similar to that depicted in FIG. 7 , except that the second impedance matching unit 776 and RF power generator 778 have been removed and a PV waveform generator 880 has been added. The PV waveform generator 880 may be used in place of the RF bias generator 778 depicted in FIG. 7 . The high-voltage power supply 780 and the PV waveform generator 880 may be DC-coupled through an RF blocking filter 782 to a sensor 724 coupled to a transmission line connected to the implanted electrode 770. The outputs of the first impedance matching unit 704 and the RF power generator 706 and / or the PV waveform generator 880 may be controlled through the use of signals provided from the sensor 724 and the tool controller 708. Information from and control of these items may be processed in the tool controller 708, which communicates with each item via individual EtherCat communication lines.

[0039] The capacitor 884 blocks high voltage DC from the high voltage power supply 780 from coupling to ground, but allows an RF return path to the sensor 724. The capacitor 884 may also function as a high pass filter and / or RF return tuning. In some embodiments, the first impedance matching unit 706 and the RF generator 704 may be coupled to the implanted electrode 770, and the sensor 724 may be coupled to the RF electrode 772. The capacitor 884 may alternatively be located between the RF blocking filter 782 and the sensor 724, instead of between the sensor 724 and ground.

[0040] It is contemplated and within the scope of the present disclosure that the RF sensing and tuning elements associated with the RF matching unit are not required to be in the same housing, and that devices on the ECAT network may be adapted to form a virtual RF measurement group. Generally, RF voltage and current sensors may be at the input and output of the impedance matching unit, or at the input only (no output sensors). According to the teachings of the present disclosure, the sensors may be located outside the impedance matching unit housing and form a virtual group with any impedance matching unit of the plasma processing equipment through the tool controller. The input and output RF sensors do not need to be physically located within the impedance matching unit housing. For example, the RF input sensor may be near the RF generators 778 and 708, and the output RF sensor may be near the RF electrode 772 and / or the workpiece pedestal 774. The tool controller 708 may collect RF sensor data and tune tuning elements in the same network. The match controller 114 is optional. In some embodiments, the tool controller 108 may communicate directly with all sensors, tuning elements, and RF generators. Also, in some other embodiments, the tool controller 108 can communicate with the shared sensor 224, the RF generator and the match controller, which can communicate with the local tuning elements and the local sensor modules 120 and / or 124. This is very easy to accomplish since all are accessible to each other via EtherCat communication.

[0041] Referring to FIG. 9 , a slave semiconductor wafer plasma processing system is depicted in accordance with certain exemplary embodiments of the present disclosure. The slave plasma processing system, generally designated by the reference numeral 900, may include a plasma chamber 102 for processing semiconductor wafers therein, an RF impedance matching unit 904, an RF power generator 106, and a tool controller 108. The impedance matching unit 904 is substantially similar to the impedance matching units 104 and 204 described above, except that there is no local sensor. Rather, all operational control of the RF tuning unit 112 and the RF power generator comes from a remote control source. The tool controller 108 may optionally be eliminated, and a remote master tool controller 108, such as that in the plasma processing systems 100 and 200 described above, is used. In some embodiments, the remote master tool controller 108 may directly control the RF tuning unit 112, and the match controller 114 may not be required.

[0042] If the slave plasma processing system 900 is substantially physically (hardware) similar to the master plasma processing system 100 or 200 and the same process recipe is used, the positions of the variable elements (e.g., variable capacitors VC1, VC2, and VC3) can be sent directly via EtherCat communication to the slave match controller 114 to directly set the tuning element positions of the RF tuning circuit 112 (replicating the master RF tuning circuit element positions). In an embodiment, local sensor modules 120 and / or 124 can optionally be placed between the RF power generator 106 and the RF filter module 122. Having all modules accessible for reading status and for control of those modules provides application flexibility.

[0043] 10, a schematic block diagram of a multi-wafer plasma processing system having one master plasma processing subsystem and multiple slave plasma processing subsystems is depicted, in accordance with certain exemplary embodiments of the present disclosure. This multi-chamber plasma processing system is an extension of the slave processing system shown in FIG. 9 and described above. For batch processing of the same semiconductor wafers using substantially the same plasma processing hardware, e.g., plasma chamber 102, impedance matching unit 104, and RF power generator 106, the same RF power and tuning element settings can be used for each plasma processing subsystem. This implementation is cost-effective for batch processing of multiple semiconductor wafers.

[0044] The master plasma processing subsystem includes modules 102a, 104a, and 106a having an RF current sensor 302, an RF voltage sensor 304, an RF phase detector 308, a frequency detector 306, a forward RF power sensor 402, and a reflected RF power sensor 404, and may operate substantially similarly to plasma processing systems 100 and 200. The other slave plasma processing subsystems simply mimic (duplicate) the RF power and tuning element settings of the master plasma processing subsystem. Optionally, all of the plasma processing subsystems may be slave systems, and a pre-recorded process recipe may control the RF power generator 106 and tuning element settings of the impedance matching unit 1004. Also, different pre-recorded process recipes may be used with each plasma chamber for batch processing of different semiconductor wafer products. The above-mentioned process options are easily implemented using EtherCat communication interconnectivity.

[0045] While this disclosure has been described in terms of one or more embodiments, it should be appreciated that many equivalents, alternatives, variations, and modifications, aside from those expressly stated, are possible and are within the scope of the present disclosure.

Claims

1. 1. A radio frequency (RF) impedance matching unit adapted for coupling between an RF power generator and a plasma processing chamber, comprising: an RF tuning circuit having a first node adapted for coupling to an RF power generator, a second node adapted for coupling to a plasma processing chamber, and an adjustable tuning element for transforming an output resistance of the RF power generator into a plurality of impedances at the second node; a match controller coupled to the adjustable tuning element of the RF tuning circuit, the match controller controlling and monitoring a position of the adjustable tuning element of the RF tuning circuit; a first communication interface coupled to the match controller for receiving and transmitting position information of the adjustable tuning element of the RF tuning circuit; an RF impedance measurement module coupled between the second node of the RF tuning circuit and the plasma processing chamber; An RF impedance matching unit comprising:

2. the RF impedance measurement module:

1. A sensor assembly comprising: an RF current sensor coupled between the second node and the plasma processing chamber; an RF voltage sensor having an input coupled to the second node; a frequency detector having an input coupled to the second node; an RF phase detector coupled to the outputs of the RF voltage sensor and the RF current sensor; a sensor assembly comprising: a microcontroller having inputs configured to receive signal information from the outputs of the RF current sensor and the RF voltage sensor, and signal information from the outputs of the frequency detector and the phase detector; a second communication interface coupled to the microcontroller and adapted to communicate the measured RF voltage, current, frequency and phase; 2. The RF impedance matching unit of claim 1, comprising:

3. 3. The RF impedance matching unit of claim 2, wherein the microcontroller calculates an RF impedance from the measured RF voltage, current, frequency and phase, and the calculated RF impedance is available for communication via the second communication interface.

4. The RF impedance matching unit of claim 1 , wherein the RF impedance measurement module is integral with the RF impedance matching unit.

5. 10. The RF impedance matching unit of claim 1, wherein the RF impedance measurement module is separate from the RF impedance matching unit and adapted for coupling between the RF impedance matching unit and the plasma processing chamber using a quick-connect coaxial RF connector.

6. The RF impedance matching unit of claim 1 , further comprising an RF power measurement module coupled between the RF power generator and the first node of the RF tuning circuit.

7. the RF power measurement module: a forward RF power sensor; a reflected RF power sensor; a microcontroller having inputs coupled to the outputs of the forward RF power sensor and the reflected RF power sensor, the microcontroller calculating a standing wave ratio (SWR) from the measured forward and reflected RF power; a third communication interface coupled to the microcontroller and adapted to communicate the measured forward and reflected RF power and the calculated SWR; and 7. The RF impedance matching unit of claim 6, comprising:

8. 8. The RF impedance matching unit of claim 7, wherein the first communication interface, the second communication interface, the third communication interface, and the fourth communication interface are adapted for communication with an Ethernet for Control Automation Technology (EtherCAT) communication protocol.

9. The RF impedance matching unit of claim 6 , wherein the RF power measurement module is integral with the RF impedance matching unit.

10. 7. The RF impedance matching unit of claim 6, wherein the RF power measurement module is separate from the RF impedance matching unit and adapted for coupling between the RF power generator and the RF impedance matching unit using a quick-connect coaxial RF connector.

11. The match controller: a microcontroller in communication with the first communication interface, an input and an output for monitoring the position of an adjustable element of a variable impedance network and for controlling the adjustable element of the variable impedance network; a memory containing information regarding a plurality of settings of one or more of the adjustable tuning elements, the information being stored in the memory; and a microcontroller having Equipped with 2. The RF impedance matching unit of claim 1, wherein the plurality of settings of one or more of the adjustable tuning elements are configured to be used to match selected ones of the plurality of impedances at the second node to an output resistance of the RF power generator.

12. 1. A system for controlling and monitoring a radio frequency (RF) power generator and an impedance matching unit adapted to generate a plasma in a plasma processing chamber, comprising: an RF power generator having an RF power output and coupled to a first communication interface for monitoring and controlling the RF power generator; an RF power measurement module coupled to the output of the RF power generator, the RF power measurement module measuring forward and reflected RF power at the output of the RF power generator and calculating a standing wave ratio (SWR) from the measured forward and reflected RF power; a second communication interface coupled to the RF power measurement module for transmitting the measured forward and reflected RF power and the calculated SWR; an RF tuning circuit having a first node coupled to the RF power measurement module and an adjustable tuning element for transforming an output resistance of the RF power generator into a plurality of impedances at a second node of the RF tuning circuit; a match controller coupled to the adjustable tuning element of the RF tuning circuit, the match controller controlling and monitoring a position of the adjustable tuning element of the RF tuning circuit; a third communication interface coupled to the match controller for receiving position information of the adjustable tuning element of the RF tuning circuit and for transmitting position information; an RF impedance measurement module coupled between the second node of the RF tuning circuit and the plasma processing chamber, the RF impedance measurement module measuring an RF voltage, an RF current, and a frequency at the second node of the RF tuning circuit, determining an RF phase from the measured RF voltage and RF current, and calculating an RF impedance at the second node from the measured RF voltage, RF current, RF phase, and frequency; a fourth communication interface coupled to the RF impedance measurement module for transmitting the measured RF voltage, RF current, RF phase, frequency and calculated impedance at the second node; a tool controller adapted to control the RF power output of the RF power generator in generating the plasma; and a fifth communication interface coupled to the tool controller; Equipped with At least two of the first communication interface, the second communication interface, the third communication interface, the fourth communication interface, and the fifth communication interface communicate with each other during an operation to generate the plasma in the plasma processing chamber.

13. 13. The system of claim 12, further comprising one or more slave RF power generators and one or more slave impedance matching units, each having a communication interface and adapted to generate plasma in one or more additional plasma processing chambers, wherein the set of process sensor modules controls operation of the one or more slave RF power generators and the one or more slave impedance matching units associated with the one or more additional plasma processing chambers.

14. The tool controller the first communication interface, the second communication interface, the third communication interface, and the fourth communication interface associated with the RF power generator, the RF power measurement module, the match controller, and the RF impedance measurement module, respectively; the communication interface associated with the one or more slave RF power generators and the one or more slave impedance matching units It is communicating with 14. The system of claim 13, wherein the tool controller receives operational configurations of the RF power generators and the impedance matching units through each of the communication interfaces of the system, and transmits the operational configurations to the one or more slave RF power generators and the one or more slave impedance matching units through each of the communication interfaces of the system.

15. the tool controller has a communication interface; and the first communication interface, the second communication interface, the third communication interface, and the fourth communication interface associated with the RF power generator, the RF power measurement module, the match controller, and the RF impedance measurement module, respectively; the communication interface associated with the one or more slave RF power generators and the one or more slave impedance matching units It is communicating with 14. The system of claim 13, wherein the tool controller receives operational configurations during a semiconductor wafer manufacturing process of the RF power generators and the impedance matching units through each of the communication interfaces of the system, and transmits the received operational configurations to the one or more slave RF power generators and the one or more slave impedance matching units through each of the communication interfaces of the system.

16. 13. The system of claim 12, wherein the RF impedance measurement module and the RF tuning circuit are in separate and distinct housings adapted for RF coupling and communication between the RF impedance measurement module and the RF tuning circuit.

17. 13. The system of claim 12, wherein the tool controller takes over operation of the match controller when it is no longer needed and communicates directly with the RF power generator, the RF power measurement module, the RF tuning circuit, and the RF impedance measurement module.

18. the RF power measurement module and the second communication interface are housed in a first housing; the RF impedance measurement module and the fourth communication interface are housed in a second housing; The system of claim 12 , wherein the first housing and the second housing are independent of each other and adapted for removal and replacement.

19. 1. A method for processing semiconductor wafers in a plurality of plasma processing systems, comprising: A master plasma processing system is provided, the master plasma processing system comprising: a master radio frequency (RF) power generator; a master impedance matching unit having a first node coupled to the master RF power generator and a second node adapted for coupling to a master plasma processing chamber, the master impedance matching unit further comprising a master RF tuning circuit having an adjustable tuning element; providing a master plasma processing system comprising: a communication interface coupled to the master RF power generator and the master impedance matching unit; providing a plurality of slave plasma processing systems, each of the plurality of slave plasma processing systems comprising: a slave RF power generator; a slave impedance matching unit having a first node coupled to the slave RF power generator and a second node adapted for coupling to a slave plasma processing chamber, the slave impedance matching unit further comprising a slave RF tuning circuit having an adjustable tuning element; providing a plurality of slave plasma processing systems, each comprising a communication interface coupled to the slave RF power generator and the slave impedance matching unit; reading a master power setting of the master RF power generator during a master plasma processing operation and communicating the master power setting to each of the slave RF power generators, each of the slave RF power generators being configured to adjust a power setting of the slave RF power generator based on the master power setting during the slave plasma processing operation; reading a master position setting of the adjustable tuning element of the master RF tuning circuit during the master plasma processing operation and communicating the master position setting to at least one of the slave impedance matching units, wherein each of the adjustable tuning elements of the slave impedance matching units is configured to adjust the adjustable tuning element of the slave impedance matching unit based on the position setting of the adjustable tuning element of the master RF tuning circuit during the slave plasma processing operation; A method comprising:

20. 20. The method of claim 19, further comprising recording the master power setting and the master position setting of the adjustable tuning element before communicating the master power setting and the master position setting to the slave RF power generator and the slave impedance matching unit.

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