Cost-effective radio frequency impedance matching network

Abstract

Embodiments provided herein generally include apparatus and methods in plasma processing systems for rapid and inexpensive repair and replacement of radio frequency (RF) sensors required for radio frequency (RF) power generation operations, and impedance matching equipment for generating plasma in a plasma chamber during semiconductor processing therein. Flexible communication between equipment of a plasma processing system allows sharing of processing information and equipment settings for batch processing of a plurality of semiconductor wafers during a manufacturing process. Operating settings of the master plasma processing system may be used to control operation of the plurality of slave processing systems. In addition, operational settings of the master plasma processing system can be recorded and reused to control the plurality of slave processing systems.

Description

Technical Field

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

[0002] In a plasma reactor chamber, an RF power supply provides RF power to the plasma reactor chamber through an impedance matching network coupled between the RF power supply and the plasma reactor chamber for generating plasma therein. The RF impedance of the plasma is a complex and highly variable function of many processing parameters and conditions. The impedance matching network maximizes the power transfer from the RF power supply to the plasma in the reactor chamber. This is accomplished when the output impedance of the impedance matching network is equal to the conjugate complex of the input impedance of the plasma in the reactor chamber. The impedance matching network converts the impedance of the plasma in the reactor chamber to the characteristic operating output impedance of the RF power supply, for example, 50 ohms, for optimal RF power transfer therefrom.

[0003] The RF impedance matching network is a circuit disposed between the RF power supply and the plasma reactor to optimize the RF power transfer efficiency. In order to optimize the RF power transfer, it is important for the RF impedance matching network to be accurately tuned to the desired complex impedance at the desired frequency. This is important for providing reliable, efficient, and predictable plasma process results. To ensure operational accuracy, the RF impedance matching network depends on the accuracy of associated RF sensors, such as RF voltage, RF current, and RF power sensors for providing real-time plasma processing conditions, such as plasma chamber impedance and RF power delivered to the plasma chamber during semiconductor manufacturing process operations. However, maintaining plasma chamber RF sensor operation and accuracy can be very time-consuming, labor-intensive, and result in expensive semiconductor process downtime.

[0004] Thus, less costly and faster repair, calibration and / or replacement of the RF sensor is required in order to maintain more operating time of the RF source and RF impedance matching network and thus increased plasma chamber processing utilization. Summary of the invention

[0005] Embodiments of the present disclosure include 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 to be coupled to the RF power generator, a second node adapted to be coupled to the plasma processing chamber, and an adjustable tuning element for converting an output resistance of the RF power generator to a plurality of impedances at the second node. The RF impedance matching unit further includes: a matching controller coupled to the adjustable tuning element of the RF tuning circuit, wherein the matching controller controls and monitors a position of the adjustable tuning element of the RF tuning circuit; and a communication interface coupled to the matching controller for receiving position information of the adjustable tuning element of the RF tuning circuit and transmitting the position information.

[0006] Embodiments of the present disclosure include a system for controlling and monitoring a radio frequency (RF) power generator and an impedance matching unit suitable for generating plasma in a plasma processing chamber. The RF power generator has an RF output and is coupled to a first communication interface to monitor and control the RF power generator. An RF power measurement module is coupled to the output of the RF power generator and measures the forward and reflected RF power at its output, and calculates a standing wave ratio (SWR) based on the measured forward and reflected RF power, and a second communication interface is coupled to the RF power measurement module to transmit the measured forward and reflected RF power and the calculated SWR. The RF tuning circuit has a first node coupled to the RF power measurement module, and an adjustable tuning element for converting the output impedance of the RF power generator to a plurality of impedances at a second node of the RF tuning circuit. A matching controller is coupled to the adjustable tuning element of the RF tuning circuit, wherein the matching controller controls and monitors the position of the adjustable tuning element of the RF tuning circuit. A third communication interface is coupled to the matching controller for receiving position information of the adjustable tuning element of the RF tuning circuit and transmitting the position information. The RF impedance measurement module is coupled between the second node of the RF tuning circuit and the plasma processing chamber, and measures the RF voltage, RF current and frequency at the second node of the RF tuning circuit, determines the RF phase from the measured RF voltage and current, and calculates the RF impedance at the second node based on the measured RF voltage, RF current, RF phase and frequency. The 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. The tool controller is adapted to control the RF power output of the RF power generator and to indicate the process recipe tuning element settings for the matching controller when generating plasma. The 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 operation of generating plasma in the plasma processing chamber.

[0007] Embodiments of the present disclosure include methods for processing a plurality of semiconductor wafers in groups using a plurality of plasma processing systems by providing a master plasma processing system, 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 suitable 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. A plurality of slave plasma processing systems are further provided, 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 suitable 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 reading a master power setting of a master RF power generator during a master plasma processing operation and transferring 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 a master RF tuning circuit during the master plasma processing operation and transferring 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 recording the master power setting and the master position setting of the adjustable tuning element before transferring the master power setting and the master position setting of the adjustable tuning element to the slave RF power generator and the slave impedance matching unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to be able to better understand in detail the manner in which the above-mentioned features of the present disclosure are used, a more specific description of the present disclosure briefly summarized herein may be made with reference to embodiments, some of which are illustrated in the accompanying drawings. However, it will be noted that the drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, and other equally effective embodiments may be allowed.

[0009] Figure 1 illustrates a schematic block diagram of a semiconductor wafer plasma processing system having a field replaceable sensor module according to a specific example embodiment of the present disclosure;

[0010] Figure 2 illustrates a schematic block diagram of a semiconductor wafer plasma processing system with a field replaceable external quick connect sensor module according to a specific example embodiment of the present disclosure;

[0011] Figure 3illustrates a schematic block diagram of an RF impedance measurement module according to a specific example embodiment of the present disclosure;

[0012] Figure 4 illustrates a schematic block diagram of an RF power measurement module according to a specific example embodiment of the present disclosure;

[0013] Figure 5A , Figure 5B and Figure 5C illustrates a schematic diagram of an RF tuning circuit according to a specific example embodiment of the present disclosure;

[0014] Figure 6 illustrates a schematic block diagram of a matching controller according to a specific example embodiment of the present disclosure;

[0015] Figure 7 is a schematic view of a plasma processing chamber having two impedance matching units according to a specific example embodiment of the present disclosure.

[0016] Figure 8 is a schematic view of a plasma processing chamber having an impedance matching unit controlled by a remote sensor according to a specific example embodiment of the present disclosure.

[0017] Fig. 9 illustrates a schematic block diagram of a system for plasma processing a semiconductor wafer according to a specific example embodiment of the present disclosure; and

[0018] Fig.10 A schematic block diagram of a plurality of semiconductor wafer plasma processing systems having a master plasma processing subsystem and a plurality of slave plasma processing subsystems according to a specific example embodiment of the present disclosure is illustrated.

[0019] To facilitate understanding, identical reference numerals have been used, where possible, to identify identical 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. DETAILED DESCRIPTION

[0020] Embodiments of the present disclosure generally relate to apparatus and methods for rapid and inexpensive defect analysis, repair, and replacement of equipment used in the manufacture of semiconductor devices. More specifically, embodiments provided herein generally include apparatus and methods for rapid and inexpensive repair and replacement of RF sensors required for radio frequency (RF) power generation operations, and impedance matching equipment for generating plasma in a plasma chamber during semiconductor processing therein.

[0021] Embodiments of the present disclosure relate to input and output process sensors, e.g., RF voltage and current, frequency, and RF power, that can be independent of an associated RF impedance matching unit in a plasma processing system and can be replaced after a failure or used for periodic recalibration without disturbing or disassembling other parts of the plasma processing system. The sensors can be inside or outside the RF impedance matching unit structure and have RF power and communication (for monitoring and control) connectors suitable for quick connection and disconnection, and can be interchangeable and reusable for design and operational expandability, e.g., sensor modules can be swapped for periodic recalibration to ensure accuracy, resulting in reduced long-term operating and maintenance costs.

[0022] Process sensors can be configured as independent and autonomous module functions with special application sensor interfaces, data processing, calculation and control. Independent module communication using high-speed and secure communication protocols provides global communication between modules, tool controllers and supervisory systems. Communication can be provided with industrial quality software protocols, such as, for example but not limited to, Ethernet (EtherCaT) or (ECAT) for control automation technology. EtherCat communication enables fast and simple module and system updates and maintenance in the field, as well as efficient testing and identification during the process of manufacturing systems. Sensor and controller module testing, identification and firmware / software updates can be completed remotely using EtherCaT-based files (FoE), which can reduce maintenance, calibration and logistics costs. Each EtherCat communication interface can have a unique address and is suitable for transmitting sensor and control data to other EtherCat communication interfaces, thereby making all processing information available to all modules in the system.

[0023] 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-learning. Modules providing sensor information can be reused for impedance matching unit design expandability. Sensor modules can be adapted for use with other impedance matching units and / or for operation at other RF frequencies and load impedances. Each sensor module can have a unique communication address and can access its data that can be used for process data recorded in all other plasma processing system modules, controllers, and manufacturing supervisory systems.

[0024] 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, a 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. In the case where the chambers and plasma processes are substantially identical, sensor information from only one processing chamber may be needed and the associated slave RF generator and impedance matching unit operations of the other processing chambers may be controlled by the pilot or master processing chamber / sensor module information (process data). This synchronization between multiple in-line plasma processes may further be shared for diagnostic purposes and algorithm pre-learning.

[0025] In some embodiments, sensor data of the plasma process can be used for learning purposes and recorded, and then the sensor can be disconnected and the recorded learning process data can be used instead of the sensor data. Process control settings (e.g., impedance matching element setting positions and RF power processing levels) can be stored in the tool controller and then used by the tool controller for multiple different process recipes. Therefore, a well-established and consistent manufacturing process can be performed without the need for sensor monitoring of the manufacturing process. This is particularly advantageous for the large number of chamber plasma processes that occur during the semiconductor device manufacturing date. The same process recipe does not need to be applied to all plasma processing systems at the same time. Depending on the manufacturing requirements of different semiconductor products, different plasma processing recipes can be distributed among the manufacturing plasma chamber systems.

[0026] Referring now to the drawings, the details of the example embodiments are schematically illustrated. The same elements in the drawings will be represented by the same numerals, and similar elements will be represented by the same numerals with different lower case letter suffixes.

[0027] See also Figure 1, a schematic block diagram of a semiconductor wafer plasma processing system is depicted according to a specific example embodiment of the present disclosure. The plasma processing system, generally represented by the reference 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 a protocol such as, for example, but not limited to, Ethernet for control automation technology (EtherCaT) or (ECAT), USB, serial RS-232, Ethernet, WiFi, and Bluetooth. For the 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, easy-to-use industrial Ethernet technology with a flexible configuration. More 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 the Ethernet packet form of communication, but is much faster and more robust than common Ethernet systems and other similar communication protocols. It is particularly suitable for industrial manufacturing processes that require high security and reliability while maintaining high data and control processing throughput in real time.

[0028] Flexibility, interchangeability, reliability, and rapid repair and replacement of defective modules are addressed in the embodiments disclosed herein. By making subsystems (e.g., equipment modules) interchangeable in the field without requiring special installation and calibration procedures, greater manufacturing uptime and lower overall system maintenance and manufacturing costs are allowed. In addition, standardization and interoperability between subsystems reduce equipment costs and enhance the ease of maintenance of equipment so designed and deployed.

[0029] The impedance matching unit 104 may include an RF tuning circuit 112, a matching controller 114 for controlling the RF tuning circuit 112, a memory 116 coupled to the matching controller 114, a safety and operation 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 matching controller 114 may include a communication interface suitable for a communication protocol, such as, for example but not limited to, EtherCat (ECAT) communication. The matching controller 114 may be an ECAT master or slave, which is an ECAT slave for an external control loop, wherein the tool controller 108 is an ECAT master. On the other hand, it is an ECAT master for the internal control loop, where the RF tuning circuit 112, the variable capacitors in the RF sensor modules 120 and / or 124 can be ECAT slaves. All of the above modules can be monitored and controlled via EtherCat (ECAT) communication.

[0030] The user interface 110 (e.g., a computer (portable computer)) can communicate with the tool controller 108 (EtherCat master) with a USB to EtherCat adapter 128, or can be coupled to the tool controller 108 using RS-232, WiFi, or other standard communication protocols not shown. This communication link allows the user interface 110 to access all sensor information and controls of the plasma processing system 100 through, for example, but not limited to, EtherCat communications coupled to each of its subsystems. The RF power from the RF power generator 106 can be coupled to the RF power measurement module 120 through a power delivery line 130 (e.g., coaxial cable type LMR-600, TRU-500, and the like), and the RF power from the impedance matching unit 104 can be coupled to the plasma chamber 102 RF coil (not shown) through a power delivery line 130a. It is contemplated and within the scope of the present disclosure that electrical conductors for delivering RF power between the module and the plasma chamber 102 may include, but are not limited to: (a) one or a combination of coaxial cables (such as a flexible coaxial cable connected in series with a rigid coaxial cable), (b) insulated high voltage corona resistant mounting wire, (c) bare wire, (d) metal rods, (e) electrical connectors, or (f) any combination of the electrical conductors / cables of (a)-(e).

[0031] See also Figure 2, a schematic block diagram of a semiconductor wafer plasma processing system with a field replaceable external quick connect sensor module is depicted according to a specific example embodiment of the present disclosure. The plasma processing system, generally indicated by the reference 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 protocols as described for the semiconductor wafer plasma processing system 100 described herein above.

[0032] The impedance matching unit 204 is substantially similar to the impedance matching unit 104 described herein above, except that at least one RF measurement module (e.g., RF impedance measurement module 224) is now located outside the housing of the impedance matching unit 204 and is coupled to the RF filter 122a using a quick connect coaxial connector 232, such as, but not limited to, an edgeless coaxial connector manufactured by Myat, Inc., available at www.myat.com. Functionally, the plasma processing system 200 is similar to the Figure 1 The plasma processing system 100 shown operates the same, but has an external RF measurement module, such as an RF impedance measurement module 224, which can be easily removed and replaced with a replacement module without disturbing any other components or having to disassemble the impedance matching unit 204 in the field. The only operation required to replace a defective RF impedance measurement module 224 in the field is to disconnect the coaxial cables 230a and 230b from the coaxial connectors 232a and 232 and the EtherCat communication cable, respectively, and then replace the defective impedance measurement unit 204 with a working impedance measurement unit, reconnect the coaxial cables 230a and 230b back to the coaxial connectors 232a and 232, and reconnect the EtherCat communication / power cable (EtherCat-P). The impedance matching unit 204 can be configured so as to be used with either an externally mounted RF measurement module and / or RF filter to facilitate field repair and / or replacement. The RF impedance measurement module 224 can be an ECAT slave device that communicates with the tool controller 108 or the matching controller 114.

[0033] RF impedance and power determination

[0034] 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 determine the phase angle θ therefrom. The frequency is measured with a frequency detector. The phase angle is the lead or lag time between the RF voltage V(t) and RF current I(t) waveforms and is expressed in degrees θ. The RF power P(t) is the product of voltage and current, or P(t)=V(t)*I(t), and the corresponding RMS (root mean square) value after sensor detection is P=V*I*cosθ, where θ is the phase angle between the voltage and current waveforms. 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 the 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.

[0035] See also Figure 3 , depicts a schematic block diagram of an RF impedance measurement module according to a specific example embodiment of the present disclosure. The 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 a memory 314 and digital signal processing (DSP) / fast Fourier transform (FFT) 316 capabilities, and an EtherCat communication interface 318. The RF impedance measurement module 124 may further have a quick connect and flangeless coaxial connector 320 to facilitate removal and installation of the RF impedance measurement module 300, and EtherCat connectors 322a and 322b. The RF coaxial connectors 320a and 320b may be bidirectional, so one may be used as an RF input and the other as an RF output. The EtherCat communication interface 318 may be adapted for EtherCat-P, which may provide DC power to the electronics of the RF impedance measurement module 124.

[0036] 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 through analog inputs of the microcontroller 312 and may subsequently be converted to digital representations thereof. The phase angle θ (the time difference between I(t) and V(t)) may be determined with the phase detector 308 or may be determined after I(t) and V(t) have been converted to digital representations. Either way, the phase angle θ may be converted to digital format by the microcontroller 312. The RF frequency detector 306 provides frequency information to the microcontroller 312 in a 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 into the load (plasma processing chamber) may be calculated using the DSP / FFT 316 function of the microcontroller 312, as described herein above. The memory 314 may be suitable for storing the calculated real-time impedance and power, and may also be used to store calibration coefficients for the RF current and voltage sensors and the frequency and phase detectors. Additionally, sensor, detector, impedance, and power information may be presented in a digital format from the microcontroller 312 to the EtherCat communication interface 318 for use (information and control) by the plasma processing system 100 and its other subsystems.

[0037] RF forward and reverse power and voltage standing wave ratio

[0038] Measurement of the forward and reverse RF power can be used to maximize the most efficient power transfer from the RF generator by adjusting the impedance matching network to match the output impedance of the RF generator (typically 50 ohms) to the complex load impedance of the plasma processing chamber. The forward and reverse RF power sensors (detectors) can be used to obtain information to adjust the impedance matching network for maximum forward RF power acceptance from the RF generator 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. Since the length of the transmission line (e.g., coaxial cable) between the RF generator and the impedance matching network is very short relative to the wavelength of the RF signal from the RF generator, the length of the transmission line can be ignored and the SWR is then used as a measure of the matching 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 considered to be 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.

[0039] The SWR can be determined by the effective forward and reflected voltages at the output of the RF generator, for the characteristic impedance that the SWR detector has been designed for. Since 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, the SWR can be expressed in terms of the forward and reflected power, where Pf is the forward power and Pr is the reflected power.

[0040]

[0041] As mentioned above, the measurement of forward and reflected RF power is not frequency dependent like the measurement of RF impedance is generally, but is based on a fixed known impedance, e.g., 50 Ohms, so the SWR measurement is also not frequency dependent. However, to be accurate, the measurement must be made at a known fixed resistance, which is why the power and SWR measurements are done at the known fixed resistance output of the RF generator, and not used on the complex impedance load side of the impedance matching network, where RF voltage, current, and frequency sensors must be relied upon after determining the plasma process impedance.

[0042] See also Figure 4 , depicts a schematic block diagram of an RF power measurement module according to a specific example embodiment of the present disclosure. The 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 a memory 414, and an EtherCat communication interface 418. The RF power measurement module 120 may further have a coaxial connector 420 that can be quickly connected and flangeless to facilitate removal and installation of the RF power measurement module 120, and EtherCat connectors 422a and 422b. The EtherCat communication interface 418 may be adapted for EtherCat-P, which may provide DC power to the electronics of the RF power measurement module 120.

[0043] The forward RF power sensor 402 senses the input RF power to 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 can be used to verify the correct operation of the RF tuning unit 112 and / or assist its matching operation (e.g., adjusting the RF tuning unit 112 for a minimum SWR and / or reflected RF power). The forward and reflected RF power values ​​from the forward and reflected RF power sensors 402 and 404, respectively, are received through analog inputs of the microcontroller 412 and can then be converted to digital representations thereof. As described herein above, the SWR at the RF output coaxial connector 420b can be calculated from the forward and reflected RF power values. The forward and reflected power, and SWR information can be presented from the microcontroller 412 to the EtherCat communication interface 418 in a digital format for use (information and control) by the plasma processing system 100 and its other subsystems (e.g., the matching controller 114).

[0044] Impedance matching unit control and tuning

[0045] See also Figure 5A , Figure 5B and Figure 5C , depicts a schematic diagram of an RF tuning circuit according to a specific example implementation of the present disclosure. Figure 5A and Figure 5B Three variable capacitors VC1, VC2 and VC3 are shown, and Figure 5C Two variable capacitors VC1 and VC3 are illustrated, for example, electrically variable vacuum capacitors, and are an example representation in combination with inductors L1 (and L2) for the RF tuning circuit 112. Variable capacitors VC1, VC2, and VC3 may have a capacitance range, but are not limited to, from about 3 pF to about 5000 pF. L1 is an inductor and may have an inductance range, but is 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 lower frequencies, a 100 MHz inductor may be implemented. Figure 5B The schematic configuration of the RF circuit shown in FIG. An additional inductor L2 may be added to adjust the RF tuning circuit 112 to a desired value. The inductor L2 may be in the range of about 0.01 μH to about 1000 μH, but is not limited thereto. The low-pass Pi matching circuit is Figure 5A and Figure 5B In some embodiments, the RF tuning circuit 112 may be as shown in FIG. Figure 5CAn L-type circuit using only two electrically powered vacuum variable capacitors (e.g., VC1 and VC3) is shown. The capacitance and / or inductance values ​​of the variable elements (e.g., VC1, VC2, VC3) can be controlled and monitored by a position control and monitoring circuit 502 for each variable element (one shown). Additional capacitors and / or inductors can also be switched into a matching circuit (not shown) as needed. The motor position actuator of the position control and monitoring circuit 502 can also include a position sensor that indicates the mechanical position of the adjustable element, such as the amount of shaft rotation of the variable vacuum capacitor or a synchronized stepper motor position count (detecting maximum and minimum clockwise and counterclockwise shaft rotation) after the minimum and maximum rotational positions have been determined. The position values ​​can be associated in a capacitance (or inductance)-position value table so that the capacitance and / or inductance values ​​can be monitored and set to a desired position based on the desired capacitance / inductance values. According to the teachings of the present disclosure, the tuning element position values ​​can be used to monitor and pre-set the tuning element position.

[0046] See also Figure 6 , depicts a schematic block diagram of a matching controller according to a specific example embodiment of the present disclosure. The matching controller 114 can monitor and control the variable elements (e.g., variable capacitors VC1, VC2, and VC3) of the RF tuning circuit 112. The matching controller 114 can include a microcontroller 612, a memory (volatile and / or non-volatile) 614, a stepper motor driver and position sensor 502 (FIG. 5), and an EtherCat communication interface 618. Through EtherCat communication, the microcontroller 612 can receive plasma chamber impedance information from an associated RF impedance measurement module 124 or 224 and / or RF power measurement module 120. The position of the variable elements (e.g., variable capacitors VC1, VC2, and VC3) of the RF tuning circuit 112 is then controlled based on this impedance information to complete impedance matching between the RF power generator 106 and the plasma chamber 102.

[0047] When in slave mode ( Fig. 9 and Fig.10 ), the microcontroller 612 can receive the position of the variable elements (e.g., variable capacitors VC1, VC2, and VC3) via EtherCat communications based on a substantially identical RF tuning circuit 112 of another plasma processing system 100 serving as a processing master. This enables the use of a slave plasma processing system ( Fig.10) to batch process the same semiconductor wafer workpieces. Alternatively, in high-volume and well-known plasma processes, the microcontroller 612 can receive the positions of the variable elements (e.g., variable capacitors VC1, VC2, and VC3) based on a pre-recorded process recipe via EtherCat communication. The process recipe containing the positions of the variable elements can be stored in the memory 614 to reduce EtherCat communication and microprocessor operation time. For autonomous plasma processes that do not require external input, this allows the process to use the process data stored in the memory 614 with the storage location during the process time.

[0048] See also Figure 7 , a schematic block diagram of a plasma processing chamber with two impedance matching units is depicted according to a specific example embodiment 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 that receives RF power from an RF power generator 706. In one example, the RF electrode 772 can be a showerhead for forming a capacitively coupled plasma in the plasma processing chamber 702, or even a multi-turn coil for forming 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. The DC blocking capacitor 784 blocks the high voltage DC from the high voltage supply 780 and can also be used as a high pass filter.

[0049] As appropriate, similar to the sensor module 224 ( Figure 2 ) may be at the output of the match 776 and / or between the base 774 and the 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. The sensor modules may be used only for learning purposes and then removed. The sensor modules may be suitable for forming a virtual matching group, for example, data measured at the output of the impedance matching unit 776 may be used to control the impedance matching unit 704. The sensor modules may also be added elsewhere, for example, roofs, pads, baffles (not shown), and may provide measurements that may be used to adjust any tuning element capacitors.

[0050] The electrical characteristics of the plasma formed by using the first impedance matching unit 704, the RF power generator 706, the second impedance matching unit 776, and the RF power generator 778 can be monitored by using the sensor module 224, which is coupled to the node located between the embedded electrode 770 and the second impedance matching unit 776 or the first impedance matching unit 704 and the RF electrode 772. Information from and control of these items can be processed in the tool controller 708, which communicate with each other through a separate EtherCat communication line. The impedance matching units 704 and 776 can be controlled by the tool controller 708 through communication on the EtherCat communication line. Which sensor information is used to control which matching unit is simply a function of how the process is programmed, because all monitoring and control can be used for all processing system elements, such as sensors, matching unit element tuning, RF power output.

[0051] See also Figure 8 , a schematic block diagram of a plasma processing chamber having an impedance matching unit controlled by a remote sensor is depicted in accordance with specific example embodiments of the present disclosure. Figure 8 The plasma processing chamber system shown is similar to Figure 7 The plasma processing chamber system shown in FIG. 1 is different in that the second impedance matching unit 776 and the RF power generator 778 have been removed, and the PV waveform generator 880 has been added. The PV waveform generator 880 can replace Figure 7 708. The high voltage supply 780 and the PV waveform generator 880 may be DC coupled to the sensor 724 through the RF blocking filter 782, which is coupled to the transmission line connected to the embedded electrode 770. The output of the first impedance matching unit 704 and the RF power generator 706, and / or the PV waveform generator 880 may be controlled by using 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 communicate with each other through independent EtherCat communication lines.

[0052] The capacitor 884 blocks the high voltage DC from the high voltage supply 780 coupled to ground, but allows an RF return path for the sensor 724. The capacitor 884 may also be used 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 embedded 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, rather than between the sensor 724 and ground.

[0053] It is contemplated and within the scope of the present disclosure that the RF sensing and tuning elements associated with the RF matching unit do not need to be in the same housing, and the devices on the ECAT network can be adapted to form a virtual RF measurement group. Typically, the RF voltage and current sensors can be at the input and output of the impedance matching unit, or only at the input (no output sensor). According to the teachings of the present disclosure, the sensor can be located outside the impedance matching unit housing and form a virtual group with any impedance matching unit on the plasma processing equipment through the tool controller. The input and output RF sensors do not have to be physically in the impedance matching unit housing. For example, the RF input sensor can be close to the RF generators 778 and 708, and the output RF sensor can be close to the RF electrode 772 and / or the workpiece base 774. The tool controller 708 can collect RF sensor data and tune the tuning elements in the same network. The matching controller 114 is optional. In some embodiments, the tool controller 108 can communicate directly with all sensors, tuning elements, and RF generators. And in some other embodiments, the tool controller 108 can communicate with the shared sensor 224, RF generator, and matching controller, and the matching controller can communicate with the local tuning elements, and local sensor modules 120 and / or 124. This is very easy to accomplish since all of these can access each other via EtherCat communications.

[0054] See also Fig. 9 , a slave semiconductor wafer plasma processing system is depicted according to a specific example embodiment of the present disclosure. The slave plasma processing system, generally indicated by reference numeral 900, may include a plasma chamber 102 for processing a semiconductor wafer 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 herein, except that there are no local sensors. Instead, all operational control of the RF tuning unit 112 and the RF power generator originates from a remote control source. Optionally, the tool controller 108 may be eliminated and a remote master tool controller 108, such as one of the plasma processing systems 100 and 200 described above herein, may be used. In some embodiments, the remote master tool controller 108 may directly control the RF tuning unit 112, and a matching controller 114 may not be required.

[0055] If the slave plasma processing system 900 is substantially physically (hardware) similar to the master plasma processing system 100 or 200, and uses the same process recipe, the positions of the variable elements (e.g., variable capacitors VC1, VC2, and VC3) can be sent directly to the slave matching controller 114 via EtherCat communications for directly setting the tuning element positions of the RF tuning circuit 112 (copying the master RF tuning circuit element positions). In some embodiments, the local sensor modules 120 and / or 124 are optionally located between the RF power generator 106 and the RF filter module 122. Having all modules accessible and controlling the read state provides application flexibility.

[0056] See also Fig.10 , a schematic block diagram of a multi-wafer plasma processing system having a master plasma processing subsystem and a plurality of slave plasma processing subsystems is depicted according to a specific example embodiment of the present disclosure. This multi-chamber plasma processing system is Fig. 9 1 and described herein above. For batch processing of the same semiconductor wafers using substantially the same plasma processing hardware (e.g., plasma chamber 192, 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 embodiment is cost effective for batch processing of multiple semiconductor wafers.

[0057] The master plasma processing subsystem may include modules 102a, 104a, and 106a having RF current sensors 302, RF voltage sensors 304, RF phase detectors 308, frequency detectors 306, forward RF power sensors 402, and reflected RF power sensors 404, and operate substantially the same as plasma processing systems 100 and 200. The other slave plasma processing subsystems will simply emulate (copy) the RF power and tuning element settings of the master plasma processing subsystem. Optionally, all plasma processing subsystems may be slave systems and pre-recorded process recipes may control the RF power generator 106 and the tuning element settings of the impedance matching unit 1004. Different pre-recorded process recipes may also be used with the respective plasma chambers for batch processing of different semiconductor wafer products. The previously mentioned processing options are easily implemented using the communication interconnectivity of EtherCat.

[0058] The disclosure has been described in terms of one or more embodiments, and it should be understood that many equivalents, alternatives, variations, and modifications besides those expressly expressed are possible and within the scope of the disclosure.

Claims

1. A radio frequency (RF) impedance matching unit adapted for coupling between a radio frequency (RF) power generator and a plasma processing chamber, the RF impedance matching unit comprising: an RF tuning circuit having a first node adapted to be coupled to an RF power generator, a second node adapted to be coupled to a plasma processing chamber, and an adjustable tuning element adapted to convert an output resistance of the RF power generator to a plurality of impedances at the second node; a matching controller coupled to the adjustable tuning element of the RF tuning circuit, wherein the matching controller controls and monitors a position of the adjustable tuning element of the RF tuning circuit; a first communication interface coupled to the matching controller to receive position information of the adjustable tuning element of the RF tuning circuit and to transmit the position information; as well as An RF impedance measurement module is coupled between the second node of the RF tuning circuit and the plasma processing chamber.

2. The RF impedance matching unit according to claim 1, wherein the RF impedance measurement module comprises: A sensor assembly, the 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; as well as an RF phase detector coupled to the output of the RF voltage and current sensor; a microcontroller having an input configured to receive signal information from the output of the RF current and voltage sensor and to receive signal information from the frequency and phase detector; as well as A second communication interface is coupled to the microcontroller and is adapted to communicate the measured RF voltage, current, frequency, and phase.

3. The RF impedance matching unit of claim 2, wherein the microcontroller calculates RF impedance based on the measured RF voltage, current, frequency and phase, wherein the calculated RF impedance can be used for transmission by the second communication interface. 4 . The RF impedance matching unit according to claim 1 , wherein the RF impedance measurement module is integrated with the RF impedance matching unit.

5. The RF impedance matching unit of claim 1, wherein the RF impedance measurement module is separate from the RF impedance matching unit and is adapted to be coupled 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 impedance matching unit of claim 6, wherein the RF power measurement module comprises: Forward RF power sensor; Reflected RF power sensor; a microcontroller having inputs coupled to the outputs of the forward and reflected RF power sensors and calculating a standing wave ratio (SWR) based on the measured forward and reflected RF powers; and A third communication interface is coupled to the microcontroller and is adapted to communicate the measured forward and reflected RF powers and the calculated SWR.

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 to communicate using 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 integrated with the RF impedance matching unit.

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

11. The RF impedance matching unit according to claim 1, wherein the matching controller comprises: A microcontroller in communication with the first communication interface and having for monitoring the position of the adjustable element of the variable impedance network and controlling the input and output of the adjustable element of the variable impedance network, and a memory including information regarding a plurality of settings of one or more of the adjustable tuning elements stored therein, Wherein the plurality of settings of one or more of the adjustable tuning elements are configured for matching a selected impedance of the plurality of impedances at the second node to the RF power generator output resistance.

12. A system for controlling and monitoring a radio frequency (RF) power generator and an impedance matching unit suitable for generating plasma in a plasma processing chamber, the system comprising: An RF power generator having an RF power output and coupled to the first communication interface to monitor and control the RF power output; An RF power measurement module is coupled to the output of the RF power generator and measures the forward and reflected RF power at the output of the RF power generator and generates an output signal based on the measured forward and reflected RF power. RF power calculation standing wave ratio (SWR); a second communication interface, coupled to the RF power measurement module, for transmitting the measured forward and reflected RF powers 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 converting an output resistance of the RF power generator to a plurality of impedances at a second node of the RF tuning circuit; a matching controller coupled to the adjustable tuning element of the RF tuning circuit, wherein the matching controller controls and monitors a position of the adjustable tuning element of the RF tuning circuit; a third communication interface, coupled to the matching controller, for receiving position information of the adjustable tuning element of the RF tuning circuit and transmitting the position information; an RF impedance measurement module coupled between the second node of the RF tuning circuit and the plasma processing chamber, and measuring an RF voltage, an RF current, and a frequency at the second node of the RF tuning circuit, determining an RF phase based on the measured RF voltage and RF current, and calculating an RF impedance at the second node based on the measured RF voltage, RF current, RF phase, and frequency; as well as 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 while generating the plasma; a fifth communication interface 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 of generating the plasma in the plasma processing chamber.

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 a 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 system of claim 13, wherein the tool controller communicates with the first communication interface, the second communication interface, the third communication interface, and the fourth communication interface respectively associated with the RF power generator, the RF power measurement module, the matching controller, and the RF impedance measurement module; as well as the communication interface associated with the one or more slave RF power generators and the one or more slave impedance matching units; wherein the tool controller receives operating configurations of the RF power generator and the impedance matching unit through the respective communication interfaces of the RF power generator and the impedance matching unit, and sends such operating configurations to the one or more slave RF power generators and the one or more slave impedance matching units through the respective communication interfaces of the one or more slave RF power generators and the one or more slave impedance matching units.

15. The system of claim 13, wherein the tool controller has a communication interface and communicates with the first communication interface, the second communication interface, the third communication interface, and the fourth communication interface respectively associated with the RF power generator, the RF power measurement module, the matching controller, and the RF impedance measurement module; as well as the communication interface associated with the one or more slave RF power generators and the one or more slave impedance matching units; wherein the tool controller receives the operating configuration of the RF power generator and the impedance matching unit through the corresponding communication interfaces of the RF power generator and the impedance matching unit during the semiconductor wafer manufacturing process, and sends the received operating configuration to the one or more slave RF power generators and the one or more slave impedance matching units through the corresponding communication interfaces of the one or more slave RF power generators and the one or more slave impedance matching units.

16. The system of claim 12, wherein the RF impedance measurement module and the RF tuning circuit are adapted for RF coupling and communication therebetween and are in different housings independent of each other.

17. The system of claim 12, wherein the tool controller replaces operation of the matching 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 system of claim 12, wherein: The RF power measurement module and the second communication interface are enclosed in a first housing; The RF impedance measurement module and the fourth communication interface are enclosed in a second housing; and The first and second housings are independent of each other and are suitable for removal and replacement.

19. A method for processing semiconductor wafers in a plurality of plasma processing systems, the method comprising: A main plasma processing system is provided, the main plasma processing system comprising: a main radio frequency (RF) power generator; a main impedance matching unit having a first node coupled to the main RF power generator and a second node adapted to be coupled to a main plasma processing chamber, the main impedance matching unit further comprising a main RF tuning circuit having an adjustable tuning element; as well as a communication interface coupled to the primary RF power generator and the primary impedance matching unit; A plurality of slave plasma processing systems are provided, each of the plurality of slave plasma processing systems comprising: From an RF power generator; a slave impedance matching unit having a first node coupled to the slave RF power generator and a second node adapted to be coupled to a slave plasma processing chamber, the slave impedance matching unit further comprising a slave RF tuning circuit having an adjustable tuning element; as well as 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, wherein each of the slave RF power generators is configured to adjust its power setting based on the master power setting during slave plasma processing operations; as well as a master position setting of the adjustable tuning element of the master RF tuning circuit is read during the master plasma processing operation and communicated to at least one of the slave impedance matching units, wherein each of the adjustable tuning elements of the slave impedance matching unit is configured to adjust its adjustable tuning element based on the position setting of the adjustable tuning element of the master RF tuning circuit during the slave plasma processing operation.

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

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