Power delivery using microwave source

Abstract

In one embodiment, the present disclosure relates to a system for controlling microwave power delivered to a distributed electrode to improve the uniformity of an electric field on the distributed electrode. The system includes an RF source circuit including at least one RF generator and a plurality of RF source circuit outputs, each outputting an RF source signal having a frequency of at least 300 MHz. For each RF source circuit output, a solid state impedance matching circuit is operably coupled to the RF source circuit output and is configured to receive an RF source signal output by the RF source circuit output. For each matching circuit, the system output is operably coupled to the matching circuit and is configured to output the RF source signal to the distributed electrodes of the load.

Description

Technical Field

[0001] The present invention relates to power delivery using a microwave source. Background Art

[0002] In semiconductor manufacturing systems, one way to reduce film deposition or etching time is to use a higher density plasma (HDP). One way to produce HDP is to increase the frequency of the RF source. However, as the frequency of the RF source increases, its wavelength decreases and becomes comparable to the size in the plasma chamber. A microwave HDP source, such as one operating at 2.45 GHz, can have a wavelength of about 120 mm in a vacuum and a shorter wavelength (20-70 mm) in a plasma. At this wavelength, the electric field can be very non-uniform. For a 300 mm wafer, the electric field variation on the electrode and therefore in the plasma can also be very non-uniform. It is necessary to make this electric field more uniform to provide better uniformity of deposited film or etching on the wafer surface. Summary of the invention

[0003] In one aspect, the present disclosure relates to a system comprising a radio frequency (RF) source circuit comprising at least one RF generator and a plurality of RF source circuit outputs, each RF source circuit output outputting an RF source signal having a frequency of at least 300 MHz; a solid-state impedance matching circuit operably coupled to the RF source circuit output for each RF source circuit output and configured to: receive the RF source signal output by the RF source circuit output; and electronically change its impedance to achieve impedance matching between the RF source circuit output and a load; and a system output operably coupled to the matching circuit for each matching circuit and configured to output the RF source signal to a distributed electrode of the load.

[0004] In another aspect, a method of controlling microwave power delivered to a distributed electrode to improve uniformity of an electric field on the distributed electrode is disclosed. The method includes an RF source circuit outputting an RF source signal having a frequency of at least 300 MHz at each of a plurality of RF source circuit outputs; for each RF source circuit output, receiving the RF source signal at a solid-state impedance matching circuit and electronically changing the impedance of the matching circuit to achieve impedance matching between the RF source circuit output and a load; and the matching circuit outputting the RF source signal to the distributed electrode of the load.

[0005] On the other hand, a semiconductor processing system includes a distributed electrode; and a power delivery system including a radio frequency (RF) source circuit, the RF source circuit including at least one RF generator and a plurality of RF source circuit outputs, each RF source circuit output outputting an RF source signal having a frequency of at least 300 MHz; a solid-state impedance matching circuit, which is operably coupled to the RF source circuit output for each RF source circuit output and is configured to: receive the RF source signal output by the RF source circuit output; and electronically change its impedance to achieve impedance matching between the RF source circuit output and a load; and a system output, which is operably coupled to the matching circuit for each matching circuit and is configured to output the RF source signal to the distributed electrode of the load.

[0006] Although the disclosed invention is applicable to semiconductor manufacturing systems, the invention is not limited thereto. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The present disclosure will become more fully understood from the detailed description and accompanying drawings, in which:

[0008] Figure 1 is a schematic diagram of a system for manufacturing a semiconductor according to an embodiment.

[0009] Figure 2 is a schematic diagram of a system for manufacturing semiconductors using a power delivery system according to one embodiment.

[0010] Figure 3 is a schematic diagram of an alternative RF source circuit according to one embodiment.

[0011] Figure 4 is a schematic diagram of a signal generator according to another embodiment.

[0012] Figures 5 to 6 is a diagram of distributed electrodes according to various embodiments.

[0013] Figure 7 is a schematic diagram of a system for manufacturing a semiconductor using a variable capacitor according to an embodiment.

[0014] Figure 8 is a schematic diagram of an electronic variable capacitor according to an embodiment.

[0015] Fig. 9 is a schematic diagram of a system for manufacturing semiconductors using magnetic coupling according to an embodiment.

[0016] The drawings represent one or more embodiments of the invention and do not limit the scope of the invention. DETAILED DESCRIPTION

[0017] The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention. The description of the illustrative embodiments is intended to be read in conjunction with the accompanying drawings, which are considered part of the entire written description. The discussion here describes and illustrates some possible non-limiting combinations of features, which may exist alone or in other combinations of features. In addition, as used herein, the term "or" will be interpreted as a logical operator that results in true whenever one or more of its operands are true. In addition, as used herein, the phrase "based on" will be interpreted as meaning "based at least in part on", and is therefore not limited to an interpretation of "completely based on". In addition, the term "each", when used to refer to each of a plurality of items, need not refer to each such item in the entire system or device, but may simply refer to each of one or more such items listed in the system.

[0018] As used throughout, ranges are used as shorthand for describing each value within the range. Any value within a range can be selected as the endpoint of the range. In addition, all references cited herein are incorporated herein by reference in their entirety. In the event of a conflict between a definition in the present disclosure and a definition in a cited reference, the present disclosure shall prevail.

[0019] In the following descriptions showing and describing block diagrams or circuits, those skilled in the art will recognize that, for clarity, not all peripheral components or circuits are shown in the drawings or described in the description. For example, common components such as memory devices and power supplies may not be discussed here because their roles will be readily understood by those of ordinary skill in the art. In addition, the terms "coupled" and "operably coupled" may refer to the direct or indirect coupling of two components of a circuit.

[0020] Note that in order to clearly and conveniently describe similar components or features, the same or similar reference numerals may be used in different embodiments or drawings. This does not mean that the components or features identified by a particular reference numeral are the same in each embodiment or drawing, but only implies that these components or features are similar in overall function or characteristics.

[0021] Features of the present invention may be implemented in software, hardware, firmware, or a combination thereof. The computer programs described herein are not limited to any particular embodiment and may be implemented in an operating system, an application, a foreground or background process, a driver, or any combination thereof. The computer programs may be executed on a single computer or server processor or on multiple computers or server processors.

[0022] The processors described herein may be any central processing unit (CPU), microprocessor, microcontroller, computing or programmable device or circuit configured to execute computer program instructions (e.g., code). The various processors may be embodied in any suitable type of computer and / or server hardware (e.g., desktop, laptop, notebook, tablet, cellular phone, etc.) and may include all common auxiliary components required to form a functional data processing device, including but not limited to buses, software and data storage, such as volatile and non-volatile memory, input / output devices, graphical user interfaces (GUIs), removable data storage, and wired and / or wireless communication interface devices including Wi-Fi, Bluetooth, LAN, etc. As used herein, the term "processor" may refer to one or more processors.

[0023] The computer-executable instructions or programs (e.g., software or code) and data described herein may be programmed into and tangibly embodied in a non-transitory computer-readable medium that may be accessed and retrieved by a corresponding processor described herein, which configures and directs the processor to perform desired functions and processes by executing the instructions encoded in the medium. A device containing a programmable processor configured to execute such non-transitory computer-executable instructions or programs may be referred to as a "programmable device" or "device", and multiple programmable devices in communication with each other may be referred to as a "programmable system". It should be noted that the non-transitory "computer-readable medium" described herein may include, but is not limited to, any suitable volatile or non-volatile memory, including random access memory (RAM) and its various types, read-only memory (ROM) and its various types, USB flash memory, magnetic or optical data storage devices (e.g., internal / external hard disks, floppy disks, tapes CD-ROMs, DVD-ROMs, optical disks, ZIP TM drives, Blu-ray discs, etc.), which can be written to and / or read by a processor operably connected to the media.

[0024] In certain embodiments, the present invention may be embodied in the form of computer-implemented processes and apparatuses, such as processor-based data processing and communication systems or computer systems for practicing those processes. The present invention may also be implemented in the form of software or computer program code contained in a non-transitory computer-readable storage medium, which, when loaded into and executed by a data processing and communication system or computer system, configures the processor to create specific logic circuits configured to implement the processes.

[0025] Semiconductor processing systems

[0026] refer to Figure 1, a semiconductor device processing system 5 utilizing an RF generator 15 is shown. The system 85 includes the RF generator 15 and a semiconductor processing tool 86. The semiconductor processing tool 86 includes a matching network 11 and a plasma chamber 19. In other embodiments, the generator 15 or other power supply may form part of a semiconductor processing tool. Commonly owned U.S. Patent No. 9,345,122 provides an example of a generator that may be applied to the generator described herein, the disclosure of which is incorporated herein by reference in its entirety.

[0027] The semiconductor device may be a microprocessor, a memory chip, or other type of integrated circuit or device. A substrate 27 (e.g., a wafer) may be placed in a plasma chamber 19, wherein the plasma chamber 19 is configured to deposit a material layer onto the substrate 27 or etch a material layer from the substrate 27. Plasma processing includes exciting a gas mixture by transferring energy to gas molecules by introducing RF energy into the gas mixture. Such a gas mixture is typically contained in a vacuum chamber (plasma chamber 19), and the RF energy is typically introduced into the plasma chamber 19 through an electrode. Thus, a plasma may be excited by coupling RF power from an RF source 15 into the plasma chamber 19 to perform deposition or etching.

[0028] In a typical plasma process, RF generator 15 generates radio frequency power which is transmitted via RF cables and networks to plasma chamber 19. In preferred embodiments, the frequency is a microwave frequency, such as 2.45 GHz or 2-3 GHz, or at least 300 MHz, or at least 800 MHz.

[0029] In order to provide efficient power transfer from the RF generator 15 to the plasma chamber 19, an intermediate circuit is used to match the fixed impedance of the RF generator 15 and the variable impedance of the plasma chamber 19. Such an intermediate circuit is often referred to as an RF impedance matching network, or more simply, an RF matching network. The purpose of the RF matching network 11 is to convert the variable plasma impedance to a value that more closely matches the fixed impedance of the RF generator 15. Commonly owned U.S. Publication Nos. 2021 / 0183623 and 2021 / 0327684 provide examples of such matching networks, the disclosures of which are incorporated herein by reference in their entirety.

[0030] Microwave Power Delivery System

[0031] Figure 28 is a schematic diagram of a system for manufacturing semiconductors using a microwave power delivery system according to an embodiment. In this embodiment, the system 85 includes a plasma chamber 19 and a power delivery system 48. The plasma chamber 19 includes a first electrode 23 and a second electrode 25, and the first and second electrodes 23, 25 are combined with an appropriate control system (not shown) and a plasma in the plasma chamber to deposit materials onto and / or etch materials from the substrate 27 in a process known in the art.

[0032] The power delivery system 48 includes an RF source circuit 46 and a matching network 11. The power delivery system 48 also includes a control circuit 45A, which may include a processor such as described herein. The control circuit 45A controls the RF source circuit and may also control the matching network 11. In this embodiment, the control circuit 45 controls the frequency source 42, the phase adjuster circuit 44, and each generator 14, while the matching network 11 has its own control circuit. The generator 14 may also have its own control circuit.

[0033] RF source circuit 46 may have a configuration similar to that described above with reference to Figure 1 Certain features of the RF source discussed. In an exemplary embodiment, the RF source circuit 46 includes at least one RF generator 14 and a plurality of RF source circuit outputs 15A, each outputting an RF source signal having a frequency of at least 300 MHz. In this embodiment, there are four RF generators 14, but there may be more or less. In an exemplary embodiment, each RF source signal is generated by a separate RF generator 14, but the invention is not limited to this. Each generator 14 may include an amplifier 14-1 configured to amplify the received RF signal. These amplifiers may be controlled by a common control circuit, such as control circuit 45A.

[0034] For each RF source circuit output 15A, a solid-state impedance matching circuit 11 is operably coupled to the RF source circuit output and is configured to receive the RF source signal output by the RF source circuit output and electronically change its impedance to achieve impedance matching between the RF source circuit output and the load. This impedance matching process will be discussed in detail below. In other embodiments, the impedance matching circuit can perform impedance matching in a non-electronic, non-solid-state manner, such as by using a vacuum variable capacitor using a motor. In other embodiments, one or more matching networks can be non-variable or fixed, so that the matching network does not provide a variable impedance.

[0035] For each matching circuit 11, a power delivery system output 17 is operably coupled to the output of the matching circuit 11 and configured to output the RF source signal to the distributed electrodes 23 of the load. Note that the system output 17 need not be directly connected to the output of the matching circuit 11.

[0036] The power delivery system 48 may also implement phase control. In an exemplary system, the RF source circuit 46 includes a frequency source 42 and a phase regulator circuit 44. The frequency source 42 is configured to transmit a signal to the phase regulator circuit. The phase regulator circuit 44 (which may include one or more circuits and may be combined with the frequency source) is configured to output a separate RF signal to each of the at least one RF generator 14. For example, the phase regulator circuit 44 may transmit a first RF signal S1 to a first generator, a second RF signal S2 to a second generator, a third RF signal S3 to a third generator, and a fourth RF signal S4 to a fourth generator. In an exemplary embodiment, each of the separate RF signals S1, S2, S3, S4 has a different phase, and the frequency source 42 and the phase regulator circuit 44 are located upstream of at least one RF generator. The phase regulator circuit 44 may be configured to phase lock the phase of each RF source signal. Phase locking may be implemented using off-the-shelf integrated circuits, such as the ADF4002BCPZ from Analog Devices or the CD74HCT7046AM96 from Texas Instruments. Using such a circuit, the system can input a reference signal and a sampled signal, and output an error signal that maintains phase lock to the reference signal. In addition, the phase adjuster circuit 44 can be configured to adjust the phase of each RF source signal based on phase-related information obtained from the distributed electrodes 23, the output of one or more matching circuits 17, the input of one or more matching circuits 17, the output of one or more of the at least one RF generator 14, or the input of one or more of the at least one RF generator 14. Note that since the communication / connections required for such adjustment will be readily understood by a person of ordinary skill in the art, these connections are not shown in the accompanying drawings. It is also noted that the present invention is not limited to the aforementioned embodiments of phase control.

[0037] Alternative RF Source Circuit

[0038] Figure 3 is a schematic diagram of an alternative RF source circuit 48 according to one embodiment. In this RF source circuit 48, instead of having multiple generators, there is only a single generator 14 that provides an RF signal to a splitter 51. The splitter 51 splits the received signal into multiple signals (four in this embodiment) and provides these signals to the phase adjuster circuit 44, which can adjust the phase of the received signal as discussed herein.

[0039] Figure 4 2 is a schematic diagram of a signal generator according to another embodiment. This embodiment is similar to that of commonly owned U.S. Publication No. 2010 / 0123502. Figure 7The embodiment shown in, which is incorporated herein by reference in its entirety. In this embodiment, the RF source circuit includes generators 14A, 14B. Generator 14A provides output phase information to other generators 14B to achieve phase control through phase signal 14C. Therefore, generator 14A can be designated as a master generator, and other generators 14B can be designated as slave generators. The phase information can be machine code, low-level RF (also known as common excitation oscillator or CEX), a combination of the two, or some other components or signals that transmit phase information between signal generators. The main signal generator 14A can coordinate the phase control of other signal generators 14B so that their respective outputs have substantially the same or different phases. Although four signal generators are shown, this number is exemplary only and is not meant to be limiting. Alternatively, a single signal generator with multiple outputs can be used instead of signal generators 14A, 14B.

[0040] In the illustrated embodiment, the master signal generator 14A is substantially similar to the slave signal generator 14B. However, the master signal generator 14A can adjust, for example, a phase shift from about 0° to about 360°, a phase increment change from about 0.01° to about 360°, and a time period between phase increment changes from about 1 microsecond to about 100 minutes. The slave signal generator 14B substantially follows the master signal generator 14A. Each slave signal generator 14B can have its own independent control loop and power measurement.

[0041] Distributed electrodes

[0042] Figures 5 to 6 is a diagram of distributed electrodes according to various embodiments. Figure 5 A multi-feed distributed electrode 23A made of a single electrode is shown, which includes multiple feeds 24 (e.g., patch antennas or other electrodes) located at different locations, each feed receiving a separate RF source signal. The number, size, and location of the feeds can vary. In this example, the feeds 24 are 60 degrees apart and are evenly spaced in azimuth around the center of the distributed electrode 23A.

[0043] In contrast, Figure 6 A segmented distributed electrode 23B is shown consisting of a plurality of electrode segments 26 adjacent to each other and separated by dielectric material 26-1, each of the plurality of electrode segments receiving a separate RF source signal via feed 24B. The number, size and location of feeds and electrodes may vary.

[0044] As above reference Figure 2As described, an exemplary load is a plasma chamber 19 that includes a first electrode 23 and a second electrode 25 that enable deposition and / or etching of material from a substrate 27. One or both of these electrodes 23, 25 may be a distributed electrode that receives an RF source signal as discussed herein. Figure 2 , the system output 17 is coupled to an electrode 23. In this embodiment, the electrode 25 is a chuck for holding a substrate 27 and / or providing an electrostatic (ESC) function. The number, size and location of the segments and feeds and electrodes may vary.

[0045] In one example, a dielectric plate is located above the distributed electrode to distribute the received energy to the electrode. The dielectric plate includes a circular face and N number of receiving regions, which are equidistant from the center of the dielectric plate. The N receiving regions are evenly spaced in azimuth around the center of the dielectric plate. The positions of the receiving regions are similar to Figure 5 The location of the feed 24 is shown. Microwave energy can be directed from the waveguide to the receiving area of ​​the dielectric slab and then distributed to the distributed electrodes.

[0046] In some embodiments, the distributed electrodes may be coupled to the system output 17 via a conductor 17A (see Figure 2 ) receives the RF source signal, and conductor 17A is directly physically connected to distributed electrodes 23, 23A, 23B. In other embodiments, the distributed electrode can receive the RF source signal via a conductor similar to conductor 17A, which is operably coupled to the system output, but is located in close proximity to the distributed electrode (or in close proximity to a dielectric plate above the distributed electrode, such as the dielectric plate described above), while the conductor does not physically contact the distributed electrode (or dielectric plate), so that RF power can be emitted from the conductor to the feed 24, 24B (or the receiving area of ​​the dielectric plate). This close proximity is not shown in the drawings, but is provided in view of the remainder of the present disclosure, including Figure 2 and conductor 17A as shown, which will be readily understood by one of ordinary skill in the art.

[0047] Impedance Matching Using Variable Reactance Elements

[0048] Figure 2 The matching circuit 11 may perform impedance matching using a variable reactance element such as a variable capacitor or a variable inductor. Figure 7 8 is a block diagram of an embodiment of a semiconductor processing system 85 having a processing tool 86 that includes an L-configuration RF impedance matching network 11. As will be discussed in further detail below, the exemplary matching network 11 uses electronic variable capacitors (EVCs) for the shunt variable capacitor 33 and the series variable capacitor 31. Note that the present invention is not limited in this regard. For example, one EVC (e.g., the shunt EVC 33) may be a mechanically variable VVC, or may be replaced with a variable inductor.

[0049] The exemplary matching network 11 has an RF input 13 connected to the RF source 15 and an RF output 17 connected to the plasma chamber 19. An RF input sensor 21 may be connected between the RF impedance matching network 11 and the RF source 15. An RF output sensor 49 may be connected between the RF impedance matching network 11 and the plasma chamber 19 so that the RF output of the impedance matching network and the plasma impedance presented by the plasma chamber 19 may be monitored. Certain embodiments may include only one of the input sensor 21 and the output sensor 49. The functions of these sensors 21, 49 will be described in more detail below.

[0050] As described above, the RF impedance matching network 11 is used to help maximize the amount of RF power delivered from the RF source 15 to the plasma chamber 19 by matching the impedance at the RF input 13 to the fixed impedance of the RF source 15. The matching network 11 can be composed of a single module within a single housing designed to be electrically connected to the RF source 15 and the plasma chamber 19. In other embodiments, the components of the matching network 11 can be located in different housings, some components can be located outside the housing, and / or some components can share a housing with components outside the matching network.

[0051] As is known in the art, the plasma within the plasma chamber 19 typically experiences certain fluctuations outside of operational control, such that the impedance presented by the plasma chamber 19 is a variable impedance. Since the variable impedance of the plasma chamber 19 cannot be completely controlled, an impedance matching network can be used to create an impedance match between the plasma chamber 19 and the RF source 15. In addition, through the design of a particular RF source 15, the impedance of the RF source 15 can be fixed at a set value. Although the fixed impedance of the RF source 15 may experience minor fluctuations during use due to, for example, temperature or other environmental changes, for impedance matching purposes, the impedance of the RF source 15 is still considered a fixed impedance because the fluctuations do not significantly change the fixed impedance from the initially set impedance value. Other types of RF sources 15 can be designed so that the impedance of the RF source 15 can be set at or during use. The impedance of this type of RF source 15 is still considered fixed because it can be controlled by the user (or at least by a programmable controller), and the set value of the impedance is known at any time during operation, thus making the set value effectively a fixed impedance.

[0052] RF source 15 generates an RF signal of appropriate frequency and power for the process performed within plasma chamber 19. RF source 15 may be electrically connected to RF input 13 of RF impedance matching network 11 using a coaxial cable which will have the same fixed impedance as RF source 15 for impedance matching purposes.

[0053] The plasma chamber 19 includes a first electrode 23 and a second electrode 25, and in a process well known in the art, the first and second electrodes 23, 25 are combined with an appropriate control system (not shown) and the plasma in the plasma chamber 19 to achieve one or both of depositing material onto the substrate 27 and etching material from the substrate 27.

[0054] In the exemplary embodiment, the RF impedance matching network 11 includes a series variable capacitor 31, a shunt variable capacitor 33, and a series inductor 35 to form an "L" type matching network. The shunt variable capacitor 33 is shown as being shunted to a reference potential between the series variable capacitor 31 and the series inductor 35, in this case ground 40, and those skilled in the art will recognize that the RF impedance matching network 11 can be configured such that the shunt variable capacitor 33 is shunted to a reference potential at the RF input 13 or the RF output 17.

[0055] Alternatively, the RF impedance matching network 11 may be configured in other matching network configurations, such as a "T" configuration or a "Π" or "π" configuration. In certain embodiments, the variable capacitor and switch circuits described below may be included in any configuration suitable for an RF impedance matching network.

[0056] In an exemplary embodiment, each of the series variable capacitor 31 and the parallel variable capacitor 33 can be an electronic variable capacitor (EVC), as described in U.S. Patent No. 7,251,121, the EVC is effectively formed as a capacitor array formed by a plurality of discrete capacitors. The series variable capacitor 31 is coupled in series between the RF input 13 and the RF output 17. The parallel variable capacitor 33 is coupled between the RF input 13 and the ground 40. In other configurations, the parallel variable capacitor 33 can be coupled between the RF output 19 and the ground 40. Other configurations can also be implemented without departing from the functionality of the RF matching network. In other configurations, the parallel variable capacitor 33 can be coupled between a reference potential and one of the RF input 13 and the RF output 19.

[0057] The series variable capacitor 31 is connected to the series RF choke and filter circuit 37 and the series driver circuit 39. Similarly, the parallel variable capacitor 33 is connected to the parallel RF choke and filter circuit 41 and the parallel driver circuit 43. Each of the series and parallel driver circuits 39, 43 is connected to the control circuit 45, which is configured with an appropriate processor and / or signal generating circuit to provide input signals for controlling the series and parallel driver circuits 39, 43. The power supply 47 is connected to each of the RF input sensor 21, the series driver circuit 39, the parallel driver circuit 43, and the control circuit 45 to provide operating power to each of these components at a designed current and voltage. The voltage level provided by the power supply 47 and therefore the voltage level used by each of the RF input sensor 21, the series driver circuit 39, the parallel driver circuit 43, and the control circuit 45 to perform their respective designated tasks is a matter of design choice. In other embodiments, various electronic components can be used to enable the control circuit 45 to send instructions to the variable capacitor. Furthermore, although the driver circuit and the RF choke and filter are shown as being separate from the control circuit 45 , these components may also be considered to form part of the control circuit 45 .

[0058] In an exemplary embodiment, the control circuit 45 includes a processor (not shown). The processor can be any type of appropriately programmed processing device (or a collection of two or more processing devices working together) configured to execute computer program instructions (e.g., code), such as a computer or microprocessor. The processor can be included in any suitable type of computer and / or server hardware (e.g., desktop, laptop, notebook, tablet, cellular phone, etc.), and can include all common auxiliary components required to form a functional data processing device, including but not limited to buses, software and data storage, such as volatile and non-volatile memory, input / output devices, graphical user interfaces (GUIs), removable data storage, and wired and / or wireless communication interface devices, including Wi-Fi, Bluetooth, LAN, etc. The processor of the exemplary embodiment is configured with specific algorithms to enable the matching network to perform the functions described herein.

[0059] Utilizing the combination of the series variable capacitor 31 and the parallel variable capacitor 33 , the control circuit 45 , the series drive circuit 39 , and the parallel drive circuit 43 may be used to control the combined impedance of the RF impedance matching network 11 and the plasma chamber 19 to match or at least substantially match the fixed impedance of the RF source 15 .

[0060] The control circuit 45 is the brain of the RF impedance matching network 11 because it receives multiple inputs from sources such as the RF input sensor 21 and the series and parallel variable capacitors 31, 33, performs the necessary calculations to determine the changes in the series and parallel variable capacitors 31, 33, and transmits commands to the series and parallel variable capacitors 31, 33 to create an impedance match. An example algorithm for generating such commands to change the capacitors to produce an impedance match is provided below. The control circuit 45 is a type of control circuit commonly used in semiconductor manufacturing processes and is therefore known to those skilled in the art. Any differences in the control circuit 45 compared to the control circuits of the prior art arise from programming differences to illustrate the speed at which the RF impedance matching network 11 is able to perform switching and impedance matching of the variable capacitors 31, 33.

[0061] Each series and parallel RF choke and filter circuit 37, 41 is configured so that a DC signal can pass between the series and parallel driver circuits 39, 43 and the corresponding series and parallel variable capacitors 31, 33, while the RF signal from the RF source 15 is blocked to prevent the RF signal from leaking into the output of the series and parallel driver circuits 39, 43 and the output of the control circuit 45. The series and parallel RF choke and filter circuits 37, 41 are of a type known to those skilled in the art.

[0062] Figure 8 FIG. 1 is a schematic diagram of a variable capacitance system 155 for switching discrete fixed capacitors of an electronic variable capacitor on and off. The variable capacitance system 155 includes a variable capacitor 151 for providing variable capacitance. The variable capacitor 151 may be similar to Figure 7 Variable capacitors 31, 33. Variable capacitor 151 has an input 113 and an output 130. Variable capacitor 151 includes a plurality of discrete fixed capacitors 153 operably coupled in parallel. The plurality of capacitors 153 include a first (fine) capacitor 151a and a second (coarse) capacitor 151b. In addition, variable capacitor 151 includes a plurality of switches 161. One of switches 161 is operably coupled in series to each of the plurality of capacitors to switch each capacitor on and off, thereby enabling variable capacitor 151 to provide a varying total capacitance. Variable capacitor 151 has a variable total capacitance, which increases when discrete capacitors 153 are switched on and decreases when discrete capacitors 153 are switched off.

[0063] The switch 161 may be coupled to the switch driver circuit 139 for driving the switch on and off. The variable capacitance system 155 may also include a control unit 145 operably coupled to the variable capacitor 151. Specifically, the control unit 145 may be operably coupled to the driver circuit 139 for instructing the driver circuit 139 to switch one or more switches 161, thereby connecting or disconnecting one or more capacitors 153. In one embodiment, the control unit 145 may form part of a control unit that controls the variable capacitor, such as a control unit that instructs the variable capacitor of the matching network to change capacitance to achieve impedance matching. The driver circuit 139 and the control unit 145 may have a configuration similar to that described above with reference to FIG. Figure 4 The features discussed can therefore also utilize the RF chokes and filters discussed above.

[0064] Note that the control circuitry can use various algorithms to achieve impedance matching. For example, the change in impedance can include determining the impedance of the plasma chamber; determining a new capacitance value for each of the at least one EVC based on the impedance of the plasma chamber; and generating a control signal to change each of the at least one EVC to the new capacitance value. This method and other methods are discussed, for example, in commonly owned U.S. Patent No. 11,521,833 (see, e.g., Figure 6 and 7 ), which is incorporated herein by reference in its entirety.

[0065] Impedance matching using magnetic coupling

[0066] In other embodiments, impedance matching may be performed by other means, such as by using magnetic coupling. Fig. 9 The matching using magnetic coupling is shown. The matching circuit 60 includes a main power line 61 and coupling lines 63, 64 to the main power line. The coupling line 63 is terminated to an open circuit and the coupling line 64 is coupled to a short circuit. The coupling line may alternatively be terminated at a specific impedance. The main power line and the coupling line may be configured to change the coupling coefficient between the main power line and the coupling line by changing the magnetic field near the coupling line. The magnetic field may be provided and changed by, for example, an adjacent DC magnet 69 as shown in the figure. The change in the magnetic field near the coupling line changes the impedance at the coupling point 62, 65 of each coupling line, which enables impedance matching. The coupling lines 63, 64 may be placed along the length of the main power line 61 so that the distance D between each coupling line is less than the wavelength (e.g., fraction thereof) of any RF source signal. Note that the present invention is not limited to any one of these embodiments.

[0067] Note that impedance matching can also be achieved by changing the frequency of one or more RF source signals. This is sometimes referred to as frequency tuning. Frequency tuning can be performed alone or in conjunction with a matching network. In other embodiments, the frequency can be substantially fixed (except for minor fluctuations), and impedance matching is instead performed by a matching network without relying on frequency tuning.

[0068] Method for controlling microwave power

[0069] Finally, in another aspect, the present invention may be understood as a method of controlling microwave power delivered to a distributed electrode to improve the uniformity of an electric field on the distributed electrode. The method includes an RF source circuit outputting an RF source signal having a frequency of at least 300 MHz at each of a plurality of RF source circuit outputs. In another operation, for each RF source circuit output, a solid-state impedance matching circuit receives the RF source signal and electronically changes the impedance of the matching circuit to achieve impedance matching between the RF source circuit output and a load. In yet another operation, the matching circuit outputs the RF source signal to the distributed electrode of the load.

[0070] The embodiments discussed herein provide several advantages. Most importantly, they improve the uniformity of the electric field on the distributed electrodes, especially when using higher frequency RF signals such as microwave signals. By making higher frequency RF sources have better electric field uniformity, semiconductor manufacturing can use these higher frequencies to achieve reduced film deposition and etching times.

[0071] Although the present invention has been described with respect to specific examples including currently preferred modes for implementing the present invention, it will be appreciated by those skilled in the art that there are multiple variations and permutations of the above-described systems and techniques. It should be understood that other embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the present invention. Therefore, the spirit and scope of the present invention should be broadly interpreted as set forth in the appended claims.

Claims

1. A system for supplying power to distributed electrodes, the system include: a radio frequency (RF) source circuit comprising at least one RF generator and a plurality of RF source circuit outputs, each RF source circuit output outputting an RF source signal having a frequency of at least 300 MHz; a solid-state impedance matching circuit operatively coupled to the RF source circuit output for each RF source circuit output and configured to: receiving an RF source signal output by an RF source circuit output; and electronically changing its impedance to achieve impedance matching between the RF source circuit output and the load; and A system output is operatively coupled to the matching circuit for each matching circuit and configured to output the RF source signal to a distributed electrode of the load.

2. The system according to claim 1, in, The RF source circuit includes at least two RF generators, and each RF source signal is generated by a separate one of the RF generators.

3. The system according to claim 1, in, The RF source circuit includes a splitter that receives a signal from one of the at least one RF generator and splits the signal into a plurality of signals that are provided to a plurality of phase adjuster circuits.

4. The system according to claim 1: in, The RF source circuit includes at least two RF generators; and One of the at least two RF generators provides output phase information to the other of the at least two RF generators to achieve phase control.

5. The system according to claim 1, in, Each generator includes an amplifier configured to amplify a received RF signal, and wherein each amplifier is controlled by a common control circuit.

6. The system according to claim 1, in, The RF source circuit also includes a frequency source and a phase adjuster circuit, the frequency source is configured to transmit a signal to the phase adjuster circuit, the phase adjuster circuit is configured to output a separate RF signal to each of the at least one RF generator, each separate RF signal having a different phase; wherein the phase adjuster circuit is located upstream of at least one RF generator, and wherein the phase adjuster circuit is configured to phase lock the phase of each RF source signal.

7. The system according to claim 6, in, The phase adjuster circuit is configured to adjust the phase of each RF source signal based on phase-related information obtained from any of: The distributed electrodes; an output of one or more of the matching circuits; an input to one or more of the matching circuits; an output of one or more of the at least one RF generator; or An input to one or more of the at least one RF generator.

8. The system according to claim 1, in, Each impedance matching circuit includes at least one electronically variable reactance element (EVRE) configured to electronically vary its reactance to achieve impedance matching.

9. The system according to claim 8, in, For each impedance matching circuit, the at least one EVRE is at least one electronic variable capacitor (EVC) comprising: Fixed capacitors; and A corresponding switch, for each fixed capacitor, is configured to switch the fixed capacitor on and off to vary the total capacitance of the EVC.

10. The system according to claim 9, in, Electronic changes to impedance to achieve impedance matching include: determining the impedance of the plasma chamber; determining a new capacitance value for each of the at least one EVC based on an impedance of the plasma chamber; and A control signal is generated to change each of the at least one EVC to a new capacitance value.

11. The system according to claim 1, in, The distributed electrode comprises an electrode including a plurality of feeds located at different positions on the electrode, each feed receiving a separate RF source signal.

12. The system according to claim 1, in, The distributed electrode includes a plurality of electrode segments adjacent to each other and separated by a dielectric material, each of the plurality of electrode segments receiving a separate RF source signal.

13. The system according to claim 1, in, The distributed electrodes receive the RF source signal via conductors operatively coupled to the system output, the conductors being directly physically connected to the distributed electrodes.

14. The system according to claim 1, in, The distributed electrode receives the RF source signal via a conductor operatively coupled to the system output, the system output being positioned in close proximity to the distributed electrode without the conductor physically contacting the distributed electrode.

15. The system according to claim 1: in, The load is a plasma chamber configured to deposit material onto or etch material from a substrate; Wherein, the plasma chamber includes two electrodes; wherein the distributed electrode is one of the two electrodes; and Therein, the RF source signal received by the distributed electrode generates plasma between the two electrodes.

16. The system according to claim 1, in, Each RF source signal has a frequency between 2 GHz and 3 GHz.

17. A system according to any one of the preceding claims, in, Each matching circuit includes a main power line and a coupled line to the main power line, wherein the coupled line is terminated in an open circuit, a short circuit or a specific impedance.

18. The system according to claim 17, in, The main power line and the coupling line are configured such that a coupling coefficient between the main power line and the coupling line is changed by changing a magnetic field near the coupling line.

19. The system according to claim 17, in, Changing the magnetic field near the coupled lines changes the impedance at the coupling point of each coupled line.

20. The system according to claim 17: in, Each matching circuit comprises a main power line and a coupling line to the main power line; and The coupled lines are placed along the length of the main power line so that the distance between each coupled line is less than the wavelength of any RF source signal.

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