Abstract:
A scalable radio frequency (RF) generator system including at least one power supply, at least one power amplifier receiving input from the power supply, and a power supply control module, and a system controller. Output from the at least one power supply can be combined and applied to each of the power amplifiers. Output form each of the at least one power amplifiers can be combined to generate a single RF signal. A compensator module controls operation of the at least one power supply. The compensator module, system control module, and power supply controller communicate in a daisy chain configuration.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/704,041, filed on Jul. 29, 2005. The disclosure of the above application is hereby incorporated herein by reference in its entirety. 
     
    
     FIELD  
       [0002]     The present disclosure relates to radio frequency (RF) power generators.  
       BACKGROUND  
       [0003]     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.  
         [0004]     RF power generators can be used in industrial applications such as fabricating integrated circuits. In these applications the RF generator is a critical element of the manufacturing process. The RF generator also interfaces with a number of other elements such as sensors, matching networks, a plasma chamber, and so forth. As such, it can be expensive, time-consuming and/or technically challenging to remove and replace a failed RF generator.  
         [0005]     Despite the apparent risks associated with a failed RF generator, modern RF generators have limited tolerance to faults or failures of internal components. For example, a single component failure in a sub-module of a RF generator can cause the RF generator to shut down. While shutting down the RF generator may be acceptable in applications that employ low power levels, e.g. up to 5 kW, it is less acceptable as power levels increase to manufacture larger-diameter silicon wafers. The limited tolerance to faults and/or failures can also cause an undesirably low mean time between failures (MTBF) in the high power RF generators.  
         [0006]     Conventional RF generators typically have limited or no persistent storage for high speed events that happen in the instant before a hard failure occurs. This can result in extended resolution times for difficult system-level issues. Due to the high complexity of wafer processing tools, components in working order may be incorrectly determined to have caused irregular system. This may result in a properly operating RF generator being returned for repair when no problem exists, which can further decrease the MTBF statistics.  
       SUMMARY  
       [0007]     According to some embodiments, radio frequency (RF) power generator including a driver module that generates RF power, a power amplifier module that amplifies the RF power and a data acquisition module. The data acquisition module includes a first communication port that receives diagnostic data associated with the power amplifier module. The data acquisition module saves the data that was received for a predetermined time prior to receiving a fault indication via the first communication port.  
         [0008]     In various embodiments, the RF power generator further includes a control module that includes a second communication port and that determines an operating parameter of the power amplifier. A power supply control module includes a third communication port and determines an operating parameter of the power supply that provides power to the power amplifier. The RF power generator further includes a daisy-chain communication link that connects the first, second, and third communication ports.  
         [0009]     In various embodiments, a radio frequency (RF) power generator includes a RF power amplifier module that generates a RF signal, a power supply that provides power to the power amplifier, and a control module that includes a first communication port and that determines an operating parameter of the power amplifier. A power supply control module includes a second communication port and determines an operating parameter of the power supply. A daisy-chain communication link connects the first and second communication ports.  
         [0010]     According to some embodiments, a radio frequency (RF) power generator includes a driver module that generates RF power, a power amplifier module that amplifies the RF power, and a power supply module that provides power to the power amplifier module. A power supply control module includes a first communication port and that limits an output parameter of the power supply module based on receiving a fault indication via the first communication port.  
         [0011]     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     DRAWINGS  
       [0012]     The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.  
         [0013]      FIG. 1  is a functional block diagram of an improved RF generator;  
         [0014]      FIG. 2  is a functional block diagram of an second embodiment of an improved RF generator; and  
         [0015]      FIG. 3  is a functional block diagram of an RF power generator that includes a combiner for combining power generated by a plurality of RF power generators. 
     
    
     DETAILED DESCRIPTION  
       [0016]     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.  
         [0017]     Referring now to  FIG. 1 , one of several embodiments is shown of a RF generator  10 . RF generator  10  includes a plurality of power amplifier modules or power amplifiers  12 - 1 ,  12 - 2 ,  12 - 3 , and  12 - 4 , collectively referred to as power amplifier  12 . Each power amplifier of power amplifier  12  includes a respective power transistor or driver module  14 - 1 ,  14 - 2 ,  14 - 3 , and  14 - 4 , collectively referred to as power transistor  14 . Output of power amplifier  12  can communicate with respective inductive clamping circuits  16 - 1 ,  16 - 2 ,  16 - 3 , and  16 - 4 , collectively referred to as inductive clamping circuit  16 . This convention for referencing similar components will be used throughout this specification. Clamping circuit  16  protects power transistor  14  from load transients and also limits the power that power transistor  14  can deliver into very low impedance loads. In some embodiments, clamping circuit  16  can be included in respective power amplifier  12 .  
         [0018]     In some embodiments, each power amplifier  12  employs a push-pull parallel power amplifier topology. In other embodiments, power amplifier  12  employs a half-bridge amplifier topology. It will be recognized by one skilled in the art that a variety of power amplifier topologies can be used to implement power amplifier  12 . For example, power amplifier  12  can also employ power transistor  14  with air cavity packaging. The air-cavity packaging allows one transistor of power transistor  14  to fail short while the remaining amplifiers of power amplifier  12  continue to operate. When an individual transistor of power transistor  14  fails short in an air-cavity package the wire bonds fuse open within the package. The open wire bonds effectively disconnect the shorted individual power transistors of power transistor  14  from the other power transistors of power transistor  14  and allow them to continue operating, such operation occurring at possibly increased electrical and thermal stresses.  
         [0019]     A plurality of power supply modules define a power supply module  18  to convert AC power to DC power for power amplifier  12 . The AC power can be  3 -phase power provided through circuit breaker  20 . The AC power can also be applied to a housekeeping power supply module  22  that generates power in conjunction with a driver power supply unit (PSU) for various modules of RF generator  10 . A line filter module  24 , such as for filtering electromagnetic interference or other typical interference, can also be employed to filter the AC power.  
         [0020]     Power supply module  18  feeds DC current to a summing module  26 . Summing module  26  sums the input DC currents and/or voltages and communicates the summed current and/or voltages to power amplifier  12 . In some embodiments, summing power supply  18  and/or module  26  can also include a filter network that filters the summed current that is provided to power amplifier  12 . If one power supply of power supply module  18  fails, then summing module  26  can disconnect the failed power supply module and thereby allow RF generator  10  to continue operating.  
         [0021]     A compensator module  28  acquires, buffers, and/or determines data such as process variables and/or respective set points, current and/or voltage provided to power amplifiers  12 , current and/or voltage provided by power amplifiers  12 , and/or temperatures of various elements and/or ambient air. The acquired data may be temporarily or somewhat permanently stored in a trace buffer. Compensator module  28 , in various embodiments, determines complex load impedance and delivered load power and outputs control signals to driver module  14  to vary operation of power amplifier module  21  to thereby adjust the RF output power from combiner/VI probe  46 . Compensator module  28 , in some embodiments, compares the data to corresponding predetermined limits and indicates a fault condition when the limits are violated. Compensator module  28 , in various embodiments, stores the acquired data for analysis. In some embodiments, compensator module  28  includes a communication port  30  for storing and/or retrieving the buffered data. Communication port  30  can employ a communication link  32 , such as Ethernet, RS-232, wireless or other type of interface and/or protocol.  
         [0022]     In some embodiments, communication link  32  provides communication paths between data acquisition module  26  and other modules such as system control module  34  and power supply control module  36 . Communication link  32  can employ high speed, error-corrected digital links that are connected in a daisy chain fashion. The daisy chain connections reduce the amount of cabling when compared to other connection topologies such as star and/or bus and therefore can improve the reliability of RF generator  10 .  
         [0023]     System control module  34  includes an interlock  40  port, a second communication port  42 , and a customer interface  44 . Interlock  40  is an input that inhibits RF generator  10  from generating RF power under certain conditions. For example, interlock  40  receives signals that indicate a shutdown condition and can act upon those signals to disable high power components in RF generator  10 . System control module  34  can also include a customer interface  48  that can be used to control and/or communicate various parameters of RF system  10 .  
         [0024]     Power supply control module  36  controls power supply modules  18  in accordance with commands from system control module  34  and/or data acquisition module  28 . Power supply control module  36  includes a communication port communicating with communication link  32 . If power supply module  36  receives a fault indication, such as via communication link  32 , then, in some embodiments, it limits an output power of one or more power supply modules  18  to protect power amplifiers  12  from damage. The fault response aspects of power supply control module  36  can cooperate with clamping circuits  16  to further protect power amplifiers  12 . In some embodiments, the response time to a fault condition is faster for clamping circuits  16  than for power supply control module  36 .  
         [0025]     Clamping circuit  16  outputs an RF signal. The RF signal passes through a combiner/VI probe  46 . CombinerNI probe  46  combines the respective RF outputs from clamping circuit  16  to generate a combined RF output. The VI probe portion of combiner/VI probe  46  is implemented in some embodiments as an integrated broadband VI probe. The VI probe provides sensed voltage and current signals to data compensator module  28 . The VI probe enables practical instantaneous determination of power and load impedance at relatively high rates of speed while rejecting undesirable signals such as intermodulation distortion products. The improved speed enables the control system to better react to load fluctuations to further increase reliability. Examples of the VI probe can be found with reference to U.S. Pat. Nos. 5,508,446 and 6,522,121, both of which are incorporated herein in their entirety.  
         [0026]      FIG. 2  depicts various embodiments of RF generator  10 . RF generator  10  of  FIG. 2  may be used to implement a lower-power configuration than RF generator  10  shown in  FIG. 1 . RF generator  10  includes power amplifier  12 , having a pair of power amplifiers, and an associated driver module  14  and clamping circuit  16 . The embodiments of RF generator  10  that are shown in  FIGS. 1-2  demonstrate the scalable nature of the architecture of RF generator  10 . In particular, power supply modules  18 - 3  and  18 - 4 , shown in phantom, represents a pair of power supply modules and accompanying power amplifier circuitry from  FIG. 1  that have been omitted in  FIG. 2  and indicates that the system of  FIG. 1  has been scaled down. Likewise, a pair of control lines output from compensator module  28  appear in phantom to further demonstrate the scalable nature of the design.  
         [0027]      FIG. 3  depicts various embodiments of RF system  100 . RF system  100  includes a plurality of RF generators  10 - 1 ,  10 - 2 , . . . ,  10 -n, collectively referred to as RF generator  10 . RF system  100  combines energy from the plurality of RF generators  10  to create a RF signal. In some embodiments, each RF generator  10  develops approximately 13 kW of RF power. The outputs of the RF generators  10  are then combined to generate between 20-40 kW at the output of RF system  100 .  FIG. 3  can be implemented, by way of example, as an integrated rack system.  
         [0028]      FIG. 3  further demonstrates the scalable nature of the system described herein. In  FIG. 3 , the RF generator units  10  of either  FIG. 1  or  FIG. 2  are implemented as basic elements in a system which combines the output of two or more RF generators  10  to produce an increased output power. In  FIG. 3 , the RF generator modules  10  are substantially the same. A single system control module  34  of  FIGS. 1 and 2  controls the RF generators  10  of  FIG. 1 .  
         [0029]     Each RF generator  10  includes, in some embodiments, a respective power supply module  18 , driver module  14 , power amplifier  12 , and associated support circuitry. Compensator  28  from FIGS.  1  or  2  appears in respective RF generators  10 - 1  and  10 - 2  as slave compensator module  28 - 1  and  28 - 2 . Slave compensator module  28  of  FIG. 3  operates similarly as described with respect to  FIGS. 1 and 2 . Each slave compensator module  28  monitors the respective outputs of the combiner/VI probe  46  (not shown in  FIG. 3 ) and generates adjustment signals to driver module  14  to control a respective PA module  12 , (not shown in  FIG. 3 ). Slave compensator module  28  also receives input from a master compensator module  128 . Master compensator module  128  receives inputs, as will be described further herein, and generates output signals to slave compensator modules  28 - 1  and  28 - 2 . System control module  34  operates similarly as described above with respect to  FIGS. 1 and 2 .  
         [0030]     Each RF generator  10  outputs a RF signal to a combiner module  102 , which operates as described above to combine the RF outputs and generate a single RF output. The single RF output is communicated to VI probe  106 . VI probe  106  generates output signals  108 - 1  and  108 - 2  which correspond to the voltage and current in the RF output signal  104 . Master compensation module  128  receives the voltage and current signals and generates output signals  112  to each slave compensator modules  128 - 1  and  128 - 2 .  
         [0031]     A power supply interlock module  114  communicates with each of RF generators  10  via interlock line  40 . Power supply interlock module  114  monitors conditions that would require disabling RF generators  10 . By way of non-limiting example, an interlock signal may be input to power supply interlock module  114  if an exposed RF connection is detected. In such an instance, power supply interlock module  114  generates signals to disable a RF generator  10 . Power supply interlock module  114  also receives an external interlock signal passed through system control module  34 . Power supply interlock module  114  communicates with system control module  34  via line  150  to also receive signals from system control module  34  that power supply interlock module  114  utilizes to control the water solenoids. By way of non-limiting example, if a condensation condition is detected by system control module  34 , system control module generates signals to power supply interlock module  114  to disable water solenoids in order to limit possible condensation within the housing for RF generator  100 . In some embodiments, system control module  34  and power supply interlock module  114  also communicate with a front panel  116  in order to provide information to the system operator.