Plasma delivery systems for modulated plasma systems

Abstract

A plasma processing system and method are disclosed. The plasma processing system includes a high frequency generator configured to deliver power to a plasma chamber and a low frequency generator configured to deliver power to the plasma chamber. A filter is coupled between the plasma chamber and the high frequency generator, and the filter suppresses a mixed product of a high frequency generated by the high frequency generator and a low frequency generated by the low frequency generator.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to plasma processing systems and, more particularly, to plasma processing systems having a modulated plasma. Background Art

[0002] Plasma processing systems for etching and deposition have been used for decades, but advances in process technology and equipment technology continue to create increasingly complex systems. These increasingly complex systems lead to more problematic interactions between multiple generators driving the same plasma system. Summary of the invention

[0003] One aspect may be characterized as a plasma processing system including a high frequency generator and a low frequency generator that both deliver power to a plasma chamber. A filter of the system is coupled between the plasma chamber and the high frequency generator, and the filter suppresses power outside a bandwidth around a frequency of the high frequency generator. The suppression of power at the frequency of the high frequency generator is at most 2 dB, and the suppression of power from the frequency of the high frequency generator at a frequency higher than the frequency of the low frequency generator is at least 2 dB higher than the suppression of power at the frequency of the high frequency generator.

[0004] Another aspect may be characterized as a plasma processing system that includes a high frequency generator configured to deliver power to a plasma chamber and a low frequency generator configured to deliver power to the plasma chamber. A filter is coupled between the plasma chamber and the high frequency generator, and the filter includes two or more helical resonators connected in parallel.

[0005] Yet another aspect may feature a method for filtering power in a plasma processing system. The method includes supplying power to a plasma chamber using a high frequency generator to ignite and maintain a plasma, and supplying power to the plasma chamber using a low frequency generator connected to the plasma. Power of the mixed products is suppressed using a filter to limit changes in a reflection coefficient of a time-varying load imparted to the high frequency generator. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a block diagram of a plasma processing system;

[0007] Figure 2 is a graph depicting how power is perceived by measuring power using different measurement system filter bandwidths;

[0008] Figure 3A 3B is a graph depicting the modulation of the load reflection coefficient, and FIG. 3C is a graph depicting when not using Figure 1 A graph of the resulting reflected power that can be seen from a high frequency generator when the filter is depicted in;

[0009] Figure 4A Including depiction Figure 1 Two graphs depicting the performance of an exemplary design of the filter, and Figure 4B Is depicted when not used Figure 1 A graph of the net power that can be delivered by the high frequency generator to the plasma load at the fundamental and mixed product frequencies when the filter depicted in FIG.

[0010] Figure 5A and Figure 5B is a graph depicting the modulation of the load reflection coefficient, and Figure 5C Is depicted when used Figure 1 A graph of the resulting reflected power that can be seen from a high frequency generator when the filter is depicted in;

[0011] Fig. 6A and Figure 6B is a graph depicting the modulation of the load reflection coefficient, and Figure 6C Is a description that can be made by Figure 1 A graph of the resulting reflected power seen by the filter depicted in;

[0012] Figure 7 is a flow chart depicting a method that may be traversed in conjunction with embodiments disclosed herein;

[0013] Fig. 8A and Figure 8B It is a reference for drawing Figure 1 A diagram of an equivalent circuit of an embodiment of the described filter;

[0014] Fig. 9 is a perspective view of an exemplary water-cooled filter design having two parallel spiral resonators;

[0015] Fig.10 is an internal view of a water-cooled filter design with two parallel spiral resonators;

[0016] Fig.11 is a cross-sectional view of a water-cooled filter design with two parallel spiral resonators;

[0017] Fig.12 is a detailed view of the capacitor block of a water-cooled filter design with two parallel spiral resonators;

[0018] Fig.13 is an exploded view of a water-cooled filter design with two parallel spiral resonators;

[0019] Fig.14 is a view of a filter including means for tuning the filter;

[0020] Fig.15 is a flow chart depicting a method that may be traversed in conjunction with embodiments disclosed herein; and

[0021] Fig.16 is a block diagram depicting a computing device that may be used in conjunction with embodiments disclosed herein. DETAILED DESCRIPTION

[0022] As power levels increase, interaction between generators driving the same plasma (where one of the generators modulates the load seen by the other generator) becomes increasingly problematic; thus, new and improved methods and systems are needed for dealing with this problem.

[0023] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0024] refer to Figure 1 , which shows a block diagram depicting an exemplary environment in which embodiments may be implemented. As shown, the plasma load of the plasma chamber 100 is coupled to the high frequency generator 102 via a filter 104 and a matching network 106. In addition, a low frequency generator 108 is also coupled to the plasma load via a match 110. In many applications, the match 106 may be combined with the match 110. Optional broadband measurement components 114, 116, 118, and 120 and an optional delay component 112 are also shown. The optional delay element 112 may be implemented using a length of coaxial cable, or a fixed or variable RLCM (i.e., a circuit containing resistors, inductors, capacitors, and coupled inductors) circuit, or a circuit containing distributed circuit elements (i.e., a transmission line circuit). Optional connections 122 and 124 are also shown, which allow one of the optional broadband measurement systems 116, 120 to take over the function of the other if the optional delay element 112 is appropriately characterized.

[0025] Although the high frequency generator 102 and the low frequency generator 108 can both operate within a range of frequencies, generally the high frequency generator 102 operates at a higher frequency than the low frequency generator 108. In many embodiments, the high frequency generator 102 can be a generator that delivers RF power to a plasma load in the plasma chamber 100 in a frequency range of 10 MHz to 200 MHz, and the low frequency generator 108 can be in a range of, for example, 100 kHz to 2 MHz. Thus, an exemplary frequency ratio of the frequency of the low frequency generator 108 to the frequency of the high frequency generator 102 is between 0.0005 and 0.2. In many embodiments, for example, the frequency ratio of the frequency of the low frequency generator 108 to the frequency of the high frequency generator 102 is less than 0.05, and in some embodiments, the frequency ratio of the low frequency generator 108 to the frequency of the high frequency generator 102 is less than 0.01. For example, the ratio can be 1:150 or approximately 0.0067.

[0026] In application, the high frequency generator 102 can be used to ignite and maintain a plasma load in the plasma chamber 100 , and the low frequency generator 108 can be used to apply a periodic voltage function to a substrate support of the plasma chamber 100 to achieve a desired ion energy distribution at a substrate surface in the plasma chamber 100 .

[0027] Regarding power levels, the low frequency generator 108 may apply relatively large amounts of power (e.g., in the 10 kW to 30 kW range) to the plasma load of the plasma chamber 100. The large amounts of power applied to the plasma at the low frequency modulates the plasma impedance imparted to the high frequency generator 102.

[0028] Applicants have discovered that in prior systems with a generator that modulates a plasma load (e.g., the low frequency generator 108), power is not measured at a sufficient amount of mixed product generated by the system. The inability to do so is a problem that results in errors in the power measurement of approximately 100% or more. The typical approach taken in the past (when there is low frequency power perturbing the plasma) is to simply filter out the mixed frequency components that result from applying high frequency power to a load modulated at a low frequency (e.g., filtering out the 59.6 MHz and 60.4 MHz components when the low and high frequency generator frequencies are 400 kHz and 60 MHz, respectively). However, when a low pass filter is used, the apparent complex impedance locus collapses to a point and, misleadingly, it appears as if the high frequency generator 102 is delivering power into the 50 ohms.

[0029] refer to Figure 2, which shows a graph depicting how power is perceived by measuring power using different measurement system filter bandwidths. Measurement system filtering is applied after down-conversion or demodulation of the measurement signal; therefore, the measurement system filters frequency components centered about the generator output frequency. For example, a measurement system bandwidth of 100kHz applied to a generator producing a 60MHz output will suppress frequency components below 59.9MHz and above 60.1MHz. As shown in the figure, when the measurement system's filter bandwidth is selected to be below the modulation frequency of the plasma, then it appears as if there is much less reflected power than is actually there (thus, it appears as if only forward power is going to the plasma load), but in reality, this is not what is happening.

[0030] In contrast, when the power is measured with sufficient bandwidth (e.g., by one or both of the broadband measurement systems 116, 120), it is apparent that only a portion of the power (e.g., only the general power) is going to the plasma load. Therefore, one aspect of the present disclosure includes adjusting the measurement system so that its filter bandwidth exceeds the modulation frequency to capture the mixing products at a higher frequency. U.S. Patent No. 7,970,562, entitled "System, Method, and Apparatus for Monitoring Power," which is incorporated herein by reference, discloses sensor types (e.g., directional couplers or voltage / current (VI) sensors) that can be used to implement sensors 114, 118 in addition to sampling and processing techniques that can be used by the broadband measurement systems 116, 120 to achieve a filter bandwidth that can capture information about the mixing products at a higher frequency. It should be noted that the filter bandwidth of the measurement systems 116, 120 should not be confused with the filter 104.

[0031] Another problem is that the high frequency generator 102 needs to deliver power to a time-varying load (modulated plasma load) where the time-averaged load reflection coefficient is high. Figure 3A 3B, which shows a graph depicting the load reflection coefficient seen by the high frequency generator 102 over a period of one cycle of the low frequency generator 108, and FIG. 3C is a graph depicting the load reflection coefficient seen by the high frequency generator 102 when not using Figure 11 is a graph of the resulting reflected power that may be seen by the high frequency generator 102 when the filter 104 is depicted in FIG. 1. As shown, the peak load reflection coefficient value seen by the high frequency generator 102 may be close to 1 (and may even exceed 1, meaning that net power is flowing from the plasma load to the high frequency generator 102), while the average load reflection coefficient value seen by the high frequency generator 102 may be 0.76. The relatively high load reflection coefficient value means that, in general, the high frequency generator 102 may have difficulty applying the desired level of power and may be more susceptible to failure. Therefore, the high frequency generator 102 may require more power devices (bipolar transistors, MOSFETs, etc.) than is typically required to deliver the desired amount of power to the plasma chamber 100.

[0032] Aspects disclosed herein relate to solutions to eliminate or mitigate plasma modulation effects. Figure 1 One aspect depicted in is the depicted filter 104. As discussed above, without the depicted filter 104, the modulated plasma load presents a time-varying, non-linear load to the high frequency generator 102, which presents challenging problems.

[0033] In many embodiments, Figure 1 The filter 104 depicted in FIG. 1 can be implemented as an extremely narrow bandwidth, high power filter that is disposed between the high frequency generator 102 and the plasma chamber 100. The filter 104 can have a relatively low loss at the frequency of the high frequency generator 102 and sufficiently suppress the mixing products to limit the variation of the load reflection coefficient given to the high frequency generator 102 at the input of the filter 104 while being stable when high power is applied. When implemented, the filter 104 can have a narrow bandwidth to filter the sideband frequencies. As used herein, bandwidth is defined as the frequency range existing between a low cutoff frequency and a high cutoff frequency, wherein each of the cutoff frequencies is 3 dB below the maximum center or resonant peak, while attenuating or weakening other frequencies outside these two points by more than 3 dB.

[0034] In some embodiments, for example, low frequency generator 108 is implemented by a 400 kHz generator and high frequency generator 102 is implemented by a 60 MHz RF generator; thus, a frequency ratio of 1 to 150 is presented. Thus, in these embodiments, filter 104 may suppress power at frequencies less than a percentage away from the center frequency.

[0035] And in many embodiments, the power is suppressed by at most 2 dB at the frequency of the high frequency generator 102, and the power from the frequency of the high frequency generator 102 is suppressed by at least 2 dB at a higher frequency than the frequency of the low frequency generator 108 than the power is suppressed at the frequency of the high frequency generator 102. In some implementations, the bandwidth of the filter 104 is 2% (or less) of the frequency of the high frequency generator 102. If the high frequency generator 102 is implemented by a 60 MHz RF generator, for example, the bandwidth of the filter may be 1.2 MHz or less.

[0036] refer to Figure 4A , which shows a graph depicting performance aspects of an exemplary design of filter 104. Figure 4A In FIG. 1 , the bandwidth of the filter 104 has a center frequency of approximately 60 MHz, and the power is suppressed by 8 dB at a fraction of a MHz away from the center frequency. Figure 4B Shown when not in use Figure 1 The net power that the high frequency generator can deliver to the plasma load when the filter is depicted. Figure 4B It shows that Figure 4A A filter having the response shown in will allow power delivered to the plasma load at a fundamental frequency of 60 MHz to be transferred from the high frequency generator 102 to the plasma load with relatively high efficiency, and suppress power reflected from the plasma load back to the high frequency generator 102.

[0037] However, ordinary technicians in this field have not yet been guided to implement Figure 4A The filter characteristics of the filter 104 are similar to those of the filter in FIG. Lack of awareness of the potential problems of plasma modulation is one reason. However, in addition, designs with Figure 4A A filter with the characteristics depicted in is challenging (even at low power levels). However, in many embodiments, filter 104 handles large amounts of power (e.g., several kW of power), and the high power and narrow band combination is not a combination that one skilled in the art would likely attempt.

[0038] As discussed above, Figure 3A and FIG. 3B depicts the load reflection coefficient seen by the high frequency generator when the filter 104 is not used. Figure 5A and Figure 5B 1 depicts the load reflection coefficient seen by the high frequency generator 102 when implementing the exemplary filter 104. Figure 5A As shown in FIG. 1 , when the filter 104 is deployed, the reflection coefficient is compressed to remain closer to the center of the graph (with respect to FIG. 1 ) within the period of plasma modulation. Figure 3A compared with the load reflection coefficient in ).

[0039] Referring to FIG. 3B , a depiction of the magnitude of the reflection coefficient in the time domain is shown without the use of filter 104. The corresponding level of forward power depicted in FIG. 3C (approximately 100 Watts) is much lower than the power used during plasma processing, but the reflection coefficient depicted in FIG. 3B and the relative magnitude of the forward and reflected power in FIG. 3C are instructive. As shown, the forward power is 99.8 Watts and the reflected power is 63.4 Watts. In contrast, Figure 5C As shown in , with the filter 104 in place, there is 99.9 watts of forward power and 3.4 watts of reflected power; therefore, the high frequency generator 102 is placed under much lower stress. And on the load side of the filter 104, as shown in Figure 6C As shown in , filter 104 can increase the average forward power.

[0040] refer to Figure 7 , which shows a flow chart 700 depicting a method for performing plasma processing in a modulated plasma system. As shown, power is supplied to the plasma chamber 100 using the high frequency generator 102 to ignite and maintain the plasma (block 710). In addition, power is supplied to the plasma chamber 100 using the low frequency generator 108 (block 720). Power transfer between the high frequency generator 102 and the plasma chamber 100 is suppressed at a frequency corresponding to a mixed product of the high frequency and the low frequency using a filter disposed between the plasma chamber 100 and the high frequency generator (block 730). The tuning of the matching network 106 can be adjusted (e.g., optimized) to balance the requirement of providing a well-matched impedance to the high frequency generator 102 with the efficiency of power transfer to the plasma chamber 100 (block 740).

[0041] Simply returning a reference Fig. 6A , note that the locus of the load reflection coefficient is not as Figure 3A This is the characteristic of the impedance required on the load side of the filter 104 in order to match the input of the filter 104 with a load reflection coefficient close to zero and obtain efficient power transfer from the high frequency generator 102 to the plasma load. Fig. 6A In FIG. 1 , the average load reflection coefficient on the load side of the filter 104 is indicated by a “+”. Fig. 6A As indicated in FIG. 1 , the average value of the load reflection coefficient on the load side of the filter 104 is approximately −0.23−j0.00. Figure 5AAs indicated in , the average value of the load reflection coefficient on the high frequency generator 102 side of the filter 104 is about 0.04-j0.02. This illustrates an aspect of using this filter 104, namely, the load reflection coefficient on the load side of the filter 104 is not tuned to a matched load (50 ohms in most systems), but is typically set to achieve a low, time-averaged load reflection coefficient value as measured by a broadband measurement system. Therefore, in many embodiments, a broadband measurement component 116 or 120 is used to capture at least a first-order mixing product. The broadband measurement component 116 or 120 can be implemented as an integrated component of the matching network 106, the high frequency generator 102, or can be implemented as a separate component. Therefore, the step of adjusting the matching network at block 740 is different from the step typically required for the matching network 106.

[0042] In many embodiments, the impedance presented by the plasma chamber 100 to the filter 104 is adjusted to optimize the efficiency of power transfer from the high frequency generator 102 to the plasma chamber 100. For example, the time average of the absolute value of the load reflection coefficient presented to the filter can be minimized, and the load reflection coefficient can be measured (e.g., by the broadband measurement component 116 or 120) using a bandwidth at least equal to the frequency of the low frequency generator 108. It is also contemplated that the time average of the load reflection coefficient is optimized to be away from 0+j0.

[0043] Reference again Figure 7 , the cable length between the matching network 106 and the filter 104 may be adjusted (e.g., optimized) to control the impedance terminated with the mixed products (block 750). While the cable length (between the matching network and the plasma processing chamber) is adjusted in other plasma processing systems (e.g., for stability), when using the filter 104, there are additional considerations in selecting the cable length, namely: the terminating impedance provided by the filter 104 to the plasma system at the frequency of the mixed products; the cable connecting the filter 104 to the matching network 106; and the matching network 106. Changing the cable length changes the nature of the modulation on the load side of the filter 104. The cable length may also affect frequency tuning in multi-state applications; therefore, the selection of the cable length may be more complicated than in existing plasma processing systems.

[0044] Fig. 8A and Figure 8B It is a reference Figure 1 An equivalent circuit of an embodiment of filter 104 is described. Fig. 8A The equivalent circuit of the lossless prototype is shown, and Figure 8BAn equivalent circuit of filter 104 is shown when simplified to practical use of achievable lossy components. There are other ways to implement such narrowband, high power filters (e.g., using large ring resonators or cavities), but in all cases close attention must be paid to the high voltages, high currents, and high power dissipation present in such filters.

[0045] Next reference Fig. 9 , shows a perspective view of the exterior of a water cooled filter 904 designed with two parallel helical resonators. The filter includes two water connections 910 and 920 for passing water through the filter for cooling, an input connector 930 and an output connector (not visible in this view).

[0046] Fig.10 1 is an internal view of a filter 904 design having two parallel spiral resonators. As shown, each of the spiral resonators includes a hollow spiral coil 1020, and each hollow spiral coil 1020 is coupled to a copper block 1024. A copper strip 1026 extends from the copper block 1024, and a ceramic insulator 1028 insulates the copper strip 1026 from the copper block 1024. In this embodiment, metallization 1030 is disposed on the ceramic 1028 to form input and output capacitors 810 and 820. In addition, each hollow spiral coil 1020 includes a ground terminal 1022. The filter 904 also includes a potted cylindrical housing 1032 (shown transparently for viewing the internal components of the filter 104) that surrounds the hollow spiral coil 1020 and the copper block 1024.

[0047] Fig.11 A cross-sectional view of filter 904 is shown. This view shows how copper ribbon 1026 is connected to input and output connectors 1110 and 1140, and to capacitors formed on ceramic insulators 1120 and 1150. This view also shows how hollow spiral coils 1130 and 1160 are connected to copper block 1024.

[0048] Fig.12 Copper block 1240 ( Fig.101024 in more detail. The assembly provides the required capacitive coupling from the input and output to the spiral resonator. Due to the small value of the required capacitor, the high voltage that the capacitor must withstand, and the power that the capacitor must dissipate, the capacitor is implemented on a ceramic substrate in the design of the filter. The copper block contains a water channel 1210, and the hollow spiral coil is attached (for example, by welding) to the water channel 1210. Therefore, the capacitor formed on the ceramic insulator 1220 and 1260 is water cooled. The ceramic insulator has a front metallization 1280 and a rear metallization 1250, respectively. The size of the front metallization 1280 controls the capacitance achieved by the assembly. The ceramic insulator can be attached to the copper block 1240 using a conductive epoxy. The strips 1270 and 1230 can be welded to the front metallization and to the connectors 1110 and 1140.

[0049] Fig.13 An exploded view of the filter 904 is shown. An insulating bracket 1310 holds the hollow spiral coil in place and provides mechanical stability to the assembly. The bracket is made of a suitable low-loss dielectric material, such as PTFE plastic or ceramic, and contains holes that allow the potting material to flow through. Due to the high voltages that may be encountered in this design, the high voltage areas of the filter are potted (e.g., using a silicone dielectric gel) to reduce the risk of failure due to air breakdown. Alternatively, the entire assembly can be evacuated to a high vacuum, or filled with a high quality dielectric liquid.

[0050] It should be appreciated that one of ordinary skill in the art, in light of the present disclosure, will be able to design aspects of the spiral coil 1020 (e.g., number of turns, radius, length, pitch, inner and outer coil diameters, and outer diameter of the coil) to achieve the desired bandwidth and heat dissipation. Figure 9-13 A variation of the design of filter 904 depicted in FIG.

[0051] Using a spiral resonator that is close to resonance at a low frequency or resonance on the inductive side, rather than an inductor, achieves similar bandwidth compared to a design using an inductor, but the spiral resonator provides a smaller effective inductance than a design with an inductor. In addition, the use of two resonators in parallel allows for grounded water cooling of the entire assembly, where the water system can remain grounded. More specifically, water provided from the grounded water system is fed through the hollow spiral coil 1020, so that a large amount of heat is dissipated. For example, the filter 904 (and variations of the filter 904) can operate at relatively high power levels (e.g., in the 1 kW to 30 kW power range). By its design, the filter 904 (and variations thereof) can operate at relatively high power levels while operating at an efficiency of at least 75%.

[0052] Fig.14A filter 1404 is shown with tuning slugs. Due to component manufacturing tolerances, tuning may be required to set the passband frequency of the filter, but the tuning may also be actively adjusted to compensate for changes in component values ​​due to, for example, self-heating of the filter 1404. The tuning slugs 1420 and 1440 may be, for example, ferrite rods that may move within the hollow helical coil 1020 along the depicted Y-axis, but more typically the tuning slugs may be made of copper. Cups 1420 and 1430 made of a suitable insulator (e.g., PTFE plastic) provide an area without potting compound in which the tuning slugs may move.

[0053] The use of filters 104, 804B, 904, 1404 compresses the frequency range over which frequency tuning (for impedance matching) can be performed to a very small frequency range. This requires a different way to handle multi-state operation of the generator. An example of multi-state operation can be switching between multiple power levels, where each power level represents a state, and where, due to the nonlinear nature of the plasma load, the high frequency generator 102 sees a different load impedance in each state, and where the high frequency generator 102 can operate at a different frequency in each state in order to improve the impedance matching or stability for that state. In order to facilitate multi-state operation in a system using filter 104, it may be necessary to ensure that the impedance given to the load side of the filter 104 for different states is along or close to an impedance line that can be matched by frequency tuning the high frequency generator 102 frequency. This can be achieved by adding a fixed or variable time delay (e.g., delay 112) on the load side of the filter.

[0054] Next reference Fig.15 , which shows a flow chart 1500 depicting a method that can be implemented in conjunction with the embodiments disclosed herein. As shown, power having a multi-state waveform is applied to the plasma chamber 100 using the high frequency generator 102 (block 1510), and power is applied to the plasma chamber 100 using the low frequency generator 108 (block 1520). The mixed products of the high frequency and the low frequency are suppressed using the filter 104 (block 1530). As shown, the power signal between the filter 104 and the plasma chamber 100 is delayed (block 1540), and the frequency of the high frequency generator 102 is adjusted during each state to adjust the impedance presented to the high frequency generator (block 1550).

[0055] Accurate power measurement may require measuring the power on the load side of a filter that has a bandwidth sufficient to capture a sufficient number of mixing products. This is because the efficiency of the filter 104 depends on the trajectory of the load impedance presented to the filter 104. Measurements on the high frequency generator 102 side of the filter 104 may not provide an accurate measurement of the power delivered to the plasma load because it is difficult, if not impossible, to account for the efficiency of the filter 104.

[0056] Those skilled in the art will appreciate that any of a variety of different technologies and techniques may be used to represent information and signals. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0057] The technician will further understand that the various illustrative logic blocks, modules, circuits and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented as electronic hardware, computer software or a combination of the two. The various illustrative logic blocks, modules and circuits described in conjunction with the embodiments disclosed herein can be implemented or executed using a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic, a discrete hardware component, or any combination thereof designed to perform the functions described herein. The general-purpose processor can be a microprocessor, but in an alternative, the processor can be any conventional processor, controller, microcontroller or state machine. The processor can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration.

[0058] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein can be implemented directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module can reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. In an alternative, the storage medium can be integrated with the processor. The processor and the storage medium can reside in an ASIC. The ASIC can reside in a user terminal. In an alternative, the processor and the storage medium can reside in a user terminal as discrete components.

[0059] refer to Fig.16, which shows an example of a computing system 1600 that can be used in conjunction with the embodiments disclosed herein. As shown, a display portion 1612 and a non-volatile memory 1620 are coupled to a bus 1622, which is also coupled to a random access memory ("RAM") 1624, a processing portion (which includes N processing components) 1626, a field programmable gate array (FPGA) 1627, and a transceiver component 628 including N transceivers. Although Fig.16 The parts depicted in the figure represent physical parts, but Fig.16 It is not intended to be a detailed hardware diagram; therefore, Fig.16 Many of the components depicted in the referenced embodiments may be implemented via a common structure or distributed in additional physical components. In addition, it is contemplated that other existing and yet to be developed physical components and architectures may be utilized to implement the referenced embodiments. Fig.16 Describes the functional components.

[0060] The display portion 1612 generally operates to provide a user interface for a user, and in several embodiments, the display is implemented by a touch screen display. Generally, the non-volatile memory 1620 is a non-transitory memory that is used to store (e.g., permanently store) data and machine-readable (e.g., processor-executable) code (including executable code associated with implementing the methods described herein). For example, in some embodiments, the non-volatile memory 1620 includes boot loader code, operating system code, file system code, and non-transitory processor executable code to facilitate the execution of the methods described with reference to Figures 4 and 5 described further herein.

[0061] In many embodiments, non-volatile memory 1620 is implemented by flash memory (e.g., NAND or ONENAND memory), but it is contemplated that other memory types may also be used. Although code from non-volatile memory 1620 may be executed, the executable code in the non-volatile memory is typically loaded into RAM 1624 and executed by one or more of the N processing components in processing portion 1626.

[0062] In operation, the N processing components connected to the RAM 1624 are generally operable to execute instructions stored in the non-volatile memory 1620 to implement aspects of the broadband measurement systems 116, 120 and to control aspects of the high frequency generator 102 (e.g., frequency tuning aspects) and the matching 106. For example, for implementing the reference Figure 7 and Fig.15The non-transitory processor-executable instructions of aspects of the described methods may be permanently stored in non-volatile memory 1620 and executed by N processing components connected to RAM 1624. As will be appreciated by one of ordinary skill in the art, processing portion 1626 may include a video processor, a digital signal processor (DSP), a graphics processing unit (GPU), and other processing components.

[0063] Additionally, or alternatively, a field programmable gate array (FPGA) 1627 may be configured to perform one or more aspects of the methods described herein (e.g., see Figure 7 and 15 For example, non-transitory FPGA configuration instructions may be permanently stored in non-volatile memory 1620 and accessed by FPGA 1627 (e.g., during startup) to configure FPGA 627 to implement aspects of broadband measurement systems 116, 120 and control aspects of high frequency generator 102 (e.g., frequency tuning aspects) and matching 106.

[0064] The input component can be operated to receive a signal indicative of one or more aspects of power (e.g., from the sensors 114, 118). The signals received at the input component can include, for example, voltage, current, forward power, reflected power, and plasma load impedance. The output component generally operates to provide one or more analog or digital signals to implement aspects of the operation of the generator 102, 108, the match 106, and / or the broadband measurement system 116, 120. For example, the output portion can provide a control signal used by the generator 102, 108, the match 106, and / or the broadband measurement system 116, 120.

[0065] The depicted transceiver component 628 includes N transceiver chains that can be used to communicate with external devices via a wireless or wired network. Each of the N transceiver chains can represent a transceiver associated with a specific communication scheme (e.g., WiFi, Ethernet, Profibus, etc.).

[0066] The previous description of the disclosed embodiments is provided to enable those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but should be consistent with the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A plasma processing system, comprising: a high frequency generator configured to deliver power to the plasma chamber; a low frequency generator configured to deliver power to the plasma chamber; as well as a filter coupled between the plasma chamber and the high frequency generator, the filter being configured to suppress power outside a bandwidth around a frequency of the high frequency generator, wherein the suppression of power at the frequency of the high-frequency generator is at most 2 dB, And wherein the suppression of power from the frequency of the high frequency generator at frequencies higher than the frequency of the low frequency generator is at least 2 dB higher than the suppression of power at the frequency of the high frequency generator.

2. The system according to claim 1, wherein: The filter is configured for ground water cooling.

3. The system according to claim 1, wherein: The bandwidth of the filter is 2% or less of the frequency of the high frequency generator.

4. The system according to claim 1, wherein: The bandwidth of the filter is 1.2 MHz or less.

5. The system according to claim 1, wherein: The filter is configured to operate in the 1 kW to 30 kW power range.

6. The system according to claim 1, wherein: The filter is configured to be at least 75% efficient.

7. The system according to claim 1, wherein: A fixed or variable time delay is inserted between the filter and the plasma chamber.

8. The system according to claim 1, wherein: The high frequency generator is configured to supply power at 60 MHz.

9. The system according to claim 1, wherein: The low frequency generator is configured to supply power at 400 kHz.

10. The system according to claim 1, wherein: The filter is tunable to compensate for manufacturing tolerances.

11. The system according to claim 1, wherein: The filter is tunable to compensate for drift due to self-heating of the filter.

12. The system of claim 1 further comprising a broadband power measurement system on the plasma chamber side of the filter.

13. A plasma processing system comprising: a high frequency generator configured to deliver power to the plasma chamber; a low frequency generator configured to deliver power to the plasma chamber; as well as A water cooling filter, the water cooling filter is coupled between the plasma chamber and the high frequency generator, the water cooling filter comprising: Two or more helical resonators connected in parallel, each of the helical resonators comprising a hollow helical coil through which water is fed for cooling.

14. The system according to claim 13, wherein: The water-cooled filter is configured for grounded water cooling.

15. The system of claim 13, wherein: The helical resonator is potted.

16. The system of claim 13, wherein: The helical resonator is configured to be capacitively coupled to the remainder of the water-cooled filter.

17. The system of claim 13, wherein: A fixed or variable time delay is inserted between the water-cooled filter and the plasma chamber.

18. A method for filtering power in a plasma processing system, comprising: supplying power to the plasma chamber using a high frequency generator to ignite and maintain the plasma; supplying power to the plasma chamber using a low frequency generator connected to the plasma; as well as The power mixing products are suppressed by filters to limit the variation of the reflection coefficient of the time-varying load presented to the high frequency generator.

19. The method according to claim 18, comprising: Ground water cooling is used to cool the filter.

20. The method according to claim 18, comprising: A power signal between the filter and the plasma chamber is delayed so that the impedance presented to the filter can be matched by frequency tuning the high frequency generator.

21. The method according to claim 18, comprising: The frequency of the high frequency generator is tuned for impedance matching.

22. The method according to claim 18, comprising: The impedance presented by the plasma chamber to the filter is adjusted to optimize the efficiency of power transfer from the high frequency generator to the plasma chamber.

23. The method according to claim 22, comprising: Minimizing the time average of the absolute value of the load reflection coefficient imparted to the filter measured with a measurement system having a bandwidth at least equal to the frequency of the low frequency generator.

24. The method according to claim 22, in, The time average of the load reflection coefficient is optimized to be away from 0+j0.

Images