(12) United States Patent
`G00dman et al.
`
`USOO6887339B1
`(10) Patent No.:
`US 6,887,339 B1
`(45) Date of Patent:
`May 3, 2005
`
`(54) RF POWER SUPPLY WITH INTEGRATED
`MATCHING NETWORK
`
`(75) Inventors: Daniel Goodman, Lexington, MA
`SRA; site,
`; Urary LJ. Alley,
`y,
`NH (US); Stephen F. Horne,
`Chelmsford, MA (US); William M.
`Holber, Winchester, MA (US)
`(73) Assignee: Applied Science and Technology, Inc.,
`Wilmington, MA (US)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(*) Notice:
`
`Y/ Y-2
`
`aKaWa C al. ............
`
`5,565,737 A * 10/1996 Keane ................... 315/111.21
`5,573.595 A * 11/1996 Dible
`... 118/723 MP
`5,643,364 A * 7/1997 Zhao et al. .............. 118/723 E
`SS A : 810: Miss al - - - - - - E.
`5,688,357. A 11/1997 Hanawa
`5,815,047 A * 9/1998 Sorensen et al. .......... 333/17.3
`6,020,795. A 2/2000 Kim
`6,027,601 A 2/2000 Hanawa
`6.211,745 B1
`4/2001 Mucke et al.
`6,222,321 B1
`4/2001 Scholl et al.
`6.229,392 B1
`5/2001 Porter et al.
`6,311,638 B1 * 11/2001 Ishii et al. .......... 118/723 MW
`OTHER PUBLICATIONS
`Fujita et al., “A 2-MHz 6-kVA Voltage-Source Inverter
`Using Low-Profile MOSFET Modules for Low–Tempera
`ture Plasma Generators.” IEEE Transactions On Power
`Electronics, vol. 14, No. 6, Nov. 1999.
`(21) Appl. No.: 09/960,227
`(Continued)
`(22) Filed:
`Sep. 20, 2001
`Primary Examiner Parviz Hassanzadeh
`Related U.S. Application Data
`(74) Attorney, Agent, or Firm-Proskauer Rose LLP
`(60) Provisional application No. 60/234,002, filed on Sep. 20,
`2000.
`(57)
`ABSTRACT
`7
`(51) Int. Cl." ........................... H05H 1700; C23C 16/00
`The invention features an RF plasma generator. The RF
`(52) U.S. Cl. ............................ 156/345.28; 156/345.48;
`plasma generator includes a variable frequency RF
`156/345.47; 156/345.41; 118/723 E; 118/723 I;
`118/723 MW generator, comprising an H-bridge and an RF Output. The
`(58) Field of Search .............................. 118/715, 723 I,
`RF generator generates electromagnetic radiation having a
`118/723 E, 723 MW; 156/345.48, 345.47,
`power. The RF plasma generator further includes a matching
`345.41, 345.28
`network that includes at least one variable impedance com
`ponent. The matching network also includes a first port that
`is electromagnetically coupled to the output of the RF
`generator and a Second port. The RF plasma generator also
`includes a load that is electromagnetically coupled to the
`Second port of the matching network, and a plasma chamber
`for containing a plasma having a power. The plasma cham
`ber is electromagnetically coupled to the load and receives
`electromagnetic radiation having a power from the load.
`Adjusting at least one of the frequency of the RF generator
`and the variable impedance component in the matching
`network changes the power in the plasma.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`2.981902. A
`4/1961 Familier ...................... 333/17
`3,509,500 A 4/1970 McNair et al. .
`... 334/47
`3,794.941 A 2/1974 Templin .........
`333/17
`3,906.405 A 9/1975 Kommrusch ....
`333/17
`4,095,198 A 6/1978 Kirby .............
`... 333/32
`4.201960 A 5/1980 Skutta et al.
`... 333/17
`4,486,722 A 12/1984 Landt ..........
`... 333/17
`4,486,723 A 12/1984 Lysobey ...................... 333/17
`5,474,648 A 12/1995 Patricket al. ......
`... 156/627.1
`5,556,549 A * 9/1996 Patricket al. ................ 216/61
`
`21 Claims, 19 Drawing Sheets
`
`485
`
`SHEATH
`
`495
`
`0.
`
`430
`
`-
`
`-
`
`-
`
`-
`
`-
`
`- 4.---------------
`
`431
`SERES
`
`432
`cSERIES
`
`AMPFER
`
`420
`
`---
`+250W BAS
`
`
`
`
`
`
`
`
`
`
`
`ONIOFF t
`
`444
`
`443
`
`* 0
`CONTROLLABLE WARIABECAPACTANCE
`
`MATCH
`
`Page 1 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`US 6,887.339 B1
`Page 2
`
`OTHER PUBLICATIONS
`Raab, “Class-EHF Power Amplifier With Electronic Tuning
`and Modulation.” Int. Microwave Symp. Digest, vol. 3, pp.
`1513–1566, Phoenix AZ May 20–25, 2001.
`El-Hamamsy, “Design of High-Efficiency RF Class-D
`Power Amplifier," IEEE Transactions On Power Elecetron
`ics, vol. 9, No. 3, May 1994.
`Koizumi et al., “Class DE High-Efficiency Tuned Power
`Amplifier," IEEE Transactions on Circuits and Systems-I:
`
`Fundamental Theory and Applications, vol. 43, No. 1, Jan.
`1996.
`Casey et al., “A High-Frequency, Low volume, Point-of
`Load Power Supply for Distributed Power Systems," IEEE
`Transactions On Power Electronics, vol. 3, No. 1, Jan. 1988,
`pp. 72-82.
`“An Intelligent Solution to RF Load-Power Variability,”vol.
`2, No. 3, 3 Quarter (1995) pp. 1-8.
`* cited by examiner
`
`Page 2 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 1 of 19
`
`US 6,887,339 B1
`
`
`
`RF
`ACF SUPPLY
`
`18
`
`FIG. 1A
`PRIOR ART
`
`
`
`
`
`RF
`SUPPLY
`
`AC
`
`F.G. 1B
`PRIOR ART
`
`Page 3 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 2 of 19
`
`US 6,887,339 B1
`
`
`
`Stable
`
`N
`
`dP/dRCO
`
`Unstable
`M
`
`FIG. 2
`
`Page 4 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 3 of 19
`
`US 6,887,339 B1
`
`impedence Z in
`-D
`L. coil (- 5 uh)
`
`Coupling
`k ho 0.35
`
`R coil (~1 Ohm)
`C4 a-25 pF
`(Moves Gnd position on cdf)-T-
`
`upon
`
`FIG. 3A
`
`
`
`Page 5 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 4 of 19
`
`US 6,887,339 B1
`
`
`
`O
`c
`
`g
`
`p
`
`N1
`O
`CC
`O
`?
`
`-
`(f)
`LU
`O.
`C
`C
`L
`1.
`
`'S
`
`s
`
`S 3.
`
`Page 6 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 5 of 19
`
`US 6,887,339 B1
`
`
`
`A " " . ' '
`
`A. C. :
`|: .
`
`.
`
`Page 7 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 6 of 19
`
`US 6,887,339 B1
`
`AC
`
`
`
`52
`
`
`
`2
`
`
`
`Page 8 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 7 of 19
`
`US 6,887,339 B1
`
`
`
`
`
`BONVOJEdWI
`
`EN?l_L
`
`
`
`
`
`NOILVWYJOHN] ESWHd '/\'||
`
`
`
`T?ORH LNO O
`
`>HEST)
`
`Page 9 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 8 of 19
`
`US 6,887,339 B1
`
`150
`
`E. FREQUENCY
`
`DSP
`
`D
`
`MUX
`
`PHASES (4)
`
`DIA
`CONTROLS (4)
`
`FREQUENCY
`
`GATE - V-CB)
`XFMR
`(C)
`
`162
`
`TOPORT2
`MUX
`
`FREQUENCY
`
`CLOCKS)
`WITH MASTER
`CLOCK
`
`
`
`172
`
`PHASE 2
`
`162
`
`TO PORT3
`MUX
`
`GATE 2
`XFMR
`
`(D
`(E)
`
`F.G. F.G.
`8A 8B
`
`FG. 8
`
`FG. 8A
`
`Page 10 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 9 of 19
`
`US 6,887,339 B1
`
`TOPORT 18
`MUX
`
`
`
`
`
`PHASE FREQ
`DETECTOR
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`(B) - 164
`C
`
`(D
`(E)
`
`LOAD
`
`MUX = MULTIPLEXER
`XFMR = TRANSFORMER
`
`178
`
`LOAD
`CURRENT
`SENSE
`
`
`
`
`
`TOPORT6
`MUX
`
`LOAD
`VOLTAGE
`SENSE
`
`
`
`
`
`180
`
`TO PORT 7
`MUX
`
`DC OFFSET
`
`168 -
`H
`
`GATE3
`is
`
`TOPORT 4
`MUX
`
`DC OFFSET
`
`GATE 4
`set
`
`TO PORT 5
`MUX
`
`FIG. 8B
`
`Page 11 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`Page 12 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 11 of 19
`
`US 6,887,339 B1
`
`340
`
`2320
`2
`370 L1
`
`1
`
`C3
`330
`
`31 O
`
`F.G. 1 O
`
`440
`
`470
`
`FAST DC
`POWER SUPPLY
`
`
`
`
`
`DELIVERED POWER AND
`PASMA IMPEDENCE
`MEASUREMENT
`
`H-BRIDGE
`RF OSCILLATOR
`
`MATCHNG
`NETWORK
`
`TRANSFORMER
`COUPLED PLASMA
`OR BAS/CHUCK
`
`
`
`
`
`DIGITAL
`FREQUENCY
`ADJUSTMENT
`
`
`
`
`
`
`
`PHASE
`MEASUREMENTS
`
`FIG 11
`
`
`
`
`
`
`
`
`
`
`
`Page 13 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 12 0f 19
`
`US 6,887,339 B1
`
`EONVOJEdWN]
`
`S[\8 OG
`
`HØVLTON
`
`
`
`Page 14 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 13 0f 19
`
`US 6,887,339 B1
`
`510
`
`520
`
`A
`
`530
`
`I,V
`P = (V - IR)
`
`FIG. 13A
`
`Page 15 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`
`
`
`
`SERJESO
`
`s
`
`Page 16 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 15 0f 19
`
`US 6,887,339 B1
`
`
`
`O
`
`V 5
`D s(c
`
`&
`s
`
`3. O
`
`C)
`
`2
`E.
`
`Page 17 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 16 0f 19
`
`US 6,887,339 B1
`
`-------------------------------------------------
`
`|
`
`| 27
`
`
`
`
`
`
`
`Page 18 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 17 of 19
`
`US 6,887,339 B1
`
`Tek
`
`
`
`
`
`
`
`
`
`e
`ps
`
`a u
`
`O
`M POS: 21.00ms CH1
`'''s
`Coupling
`it..............BW Limit
`. . .
`. . . .
`. . .
`. . . . 100MHz
`VoltS/Div
`
`
`
`a a s s w w
`
`a
`
`v vs.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`. w w w w w w w a q
`
`w
`
`4 4 & & 4 W 6 w w w w w m
`
`w v.
`
`v.
`
`v.
`
`v v i
`
`u in a s is a n
`
`4
`
`a
`
`v
`
`w w us a
`
`- w a a
`
`a v -
`
`a
`
`r
`
`u o
`
`CH12O.OV CH2 10.OV M25.0ms
`25 ns/div
`FET Turn-On
`
`Ext J40.00mV
`
`F G 1 6A
`
`... i.i.at it
`
`IE
`
`i.
`
`, ,
`
`y
`W 4 a w w to w w w
`
`V
`
`us
`
`a
`
`A
`
`r
`
`n n v s r
`
`u v
`
`s is
`
`A
`
`t
`
`w
`
`a v
`
`V a 9
`
`8
`
`a
`
`a
`
`a
`
`VV
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`. .
`
`e o w
`
`w w a v
`
`A
`
`w w w w
`
`a n w a
`
`s n
`
`a
`
`s a
`
`v
`
`1
`A. A
`CH12O.OV CH2 10.OV M50.Oms
`50 mS/div
`FET Tun-off
`
`Ext J40.OmV
`
`FIG. 16B
`
`Page 19 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 18 of 19
`
`US 6,887,339 B1
`
`1200
`
`
`
`9 O O
`
`6 O O
`
`3 O O
`
`O
`
`2700 pff (v0.6)'
`
`100
`50
`VDS (Volts)
`
`FIG. 17
`
`150
`
`Page 20 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`U.S. Patent
`
`May 3, 2005
`
`Sheet 19 of 19
`
`US 6,887,339 B1
`
`?JO|-------------------------------------+-----
`
`-
`
`Page 21 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`1
`RF POWER SUPPLY WITH INTEGRATED
`MATCHING NETWORK
`
`RELATED APPLICATIONS
`This application claims the benefit of U.S. Provisional
`Patent Application Ser. No. 60/234,022, filed Sep. 20, 2000,
`the entire contents of which are hereby incorporated by
`reference.
`
`FIELD OF THE INVENTION
`The present invention relates generally to RF and micro
`wave power Supplies and to RF and microwave plasma
`processing equipment. In particular, the present invention
`relates to RF and microwave power Supplies for generating
`RF or microwave plasmas in a plasma processing chambers.
`
`15
`
`BACKGROUND OF THE INVENTION
`Radio Frequency (RF) or microwave power Supplies
`(hereafter “RF power supplies”) are widely used in semi
`conductor and industrial plasma processing equipment to
`generate plasmas in a process chamber. Plasma processing is
`used for a wide variety of applications, including etching of
`materials from Substrates, deposition of materials on to
`Substrates, cleaning of Substrate Surfaces, and modification
`of Substrate Surfaces. The frequency and power levels
`employed vary widely, from about 10 kHz to 2.45 GHz and
`from a few Watts to as much as 100 kW or greater. For
`Semiconductor processing applications, the range of fre
`quencies and powers presently used in plasma processing
`equipment is Somewhat narrower, ranging from about 10
`KHZ to 2.45 GHz and 10 W to 30 kW, respectively.
`Prior art RF power Supplies used in plasma Sources for
`plasma processing equipment generally have expensive and
`complex power generation and delivery Systems. These
`plasma Sources require a precision RF power generator, a
`power delivery System, a matching network, and metrology
`(measuring) equipment. In addition, precision instrumenta
`tion is usually required to control the actual power reaching
`the plasma The cost of these prior art RF power Supplies can
`be a considerable fraction of the total System cost.
`The impedance of plasma loads can vary considerably in
`response to variations in gas recipe, plasma density, deliv
`ered RF power, pressure and other parameters. The RF
`Supply can deliver power to the plasma in a number of
`different ways. This can include inductive coupling via an
`antenna Structure, capacitive coupling, launching a Wave,
`exciting a resonant cavity, etc. The RF Supply generally
`requires proper matching to the load impedance.
`An antenna typically has a primarily inductive load
`impedance, with a Smaller resistive component. In contrast,
`a Sample holder or "chuck” typically presents a primarily
`capacitive impedance, also with a Smaller resistive compo
`nent. RF power can be delivered to these loads via an
`impedance matching network.
`Most prior art RF generators for plasma processing equip
`ment are designed to have a Standard fifty-ohm output
`impedance. A matching network is required because the load
`represented by the process chamber and the plasma can vary
`widely and rapidly, causing mismatches in impedance
`between the standard fifty-ohm output impedance of the RF
`generator and the input of the load. A mismatch in the
`impedance of the generator and the plasma Source causes
`great StreSS on electronics devices in the RF generator and
`the matching network and can cause premature failure
`because of either electrical or thermal stress or both.
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`US 6,887,339 B1
`
`2
`Consequently, the reliability of prior art RF generators
`and matching networks is relatively low and is considered to
`be below desired standards of the semiconductor industry.
`The relatively low reliability increases the total cost of
`ownership (COO) of the plasma processing tool, since time
`must be spent in diagnosing failures and repairing or replac
`ing defective RF equipment. Impedance mismatch also
`causes the power delivered to the plasma to vary, which can
`cause process inconsistency both within a chamber for
`Successive Substrates and among Similar chambers.
`Prior art matching networks are positioned in the power
`delivery system between the output of the RF generator and
`the input of the process chamber. The matching network
`provides a means of matching the output impedance of the
`generator to the input impedance of the proceSS chamber.
`The matching network may contain fixed elements only, or
`it may contain elements Such as variable capacitors and
`variable inductors, which can allow dynamic impedance
`matching of the generator to a changing load.
`In recent years it has become common to use frequency
`tuning to carry out dynamic impedance matching. The
`matching network for dynamic impedance matching Sys
`tems employing frequency tuning typically contains only
`fixed elements. Changes in load impedance can be accom
`modated by slightly varying the RF frequency. Dynamic
`impedance matching generally provides faster tuning Speed,
`higher reliability, lower cost, and lower size. The dynamic
`tuning range, however, is relatively low.
`A matching network having fixed reactive elements can
`be used to transform a reactive load to a load that appears
`purely resistive and can also be efficiently driven by a
`variable frequency RF Supply. This approach, however,
`would typically require a very wide frequency range, e.g.
`+/-30%, because the load impedance can vary widely, e.g.,
`+/-200%. Such a wide frequency range is unacceptable for
`processing reasons and also because of potential interference
`with other equipment protected using narrow-band filters.
`A matching network of variable vacuum capacitors driven
`by Servo-motorS may accommodate a widely varying load.
`Mechanical motors, however, are relatively slow, while
`Vacuum variable capacitors are expensive.
`An approach for faster mechanical tuning is described in
`U.S. Pat. No. 5,654,679 to Mavretic, et al. This approach
`employs PIN diodes or relay switches to add or remove
`capacitors as participants in a matching network to maintain
`a Somewhat constant load impedance, as presented to the RF
`Supply.
`This approach has Several disadvantages. The matching
`network is complex because it requires many Switches. PIN
`diodes are Susceptible to breakdown and are relatively
`expensive. Switching is performed in a discontinous fash
`ion; a PIN diode or relay has a binary state - either on or off.
`This can cause discontinous jumps in the resonant frequency
`and impedance Seen by the RF Supply, as well as off
`resonance operation of the RF Supply while the resonant
`frequency is re-established by a feedback control loop.
`Off-resonance operation can cause significant StreSS on field
`effect transistor (“FET) switches. Reduction of these prob
`lems requires, for example, use of many PIN diode Switches,
`each requiring an associated capacitor and driving circuitry.
`SUMMARY OF THE INVENTION
`Various embodiments of the invention remedy many
`limitations encountered in prior art RF powered plasma
`systems. One embodiment provides a direct RF power
`Supply, that is, a closely-coupled plasma processing System
`
`Page 22 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`US 6,887,339 B1
`
`15
`
`35
`
`40
`
`25
`
`3
`in which the RF power Supply is co-located in a single unit
`with matching network components. The RF Supply unit is
`located immediately adjacent to a load that delivers power to
`a plasma. The load may be, for example, an antenna or a
`Substrate holder.
`In a closely-coupled System, there is no need to employ a
`discrete, Separate cable to connect an RF generator to a
`network or to the load of a plasma processing tool. Hence,
`potential instabilities due to cable Selection are eliminated.
`Further embodiments eliminate use of mechanical compo
`nents within an impedance matching network. This removes
`instability due to Such components as motor-driven vacuum
`capacitors in the matching network.
`Some embodiments employ power MOSFETs. Digital
`circuitry provides fast control of the phase of FET drivers to
`optimize efficiency, and reduce Spurious harmonic content.
`Measurement and control of power and phase parameters in
`real time may Support the control of plasma instabilities.
`Attaching a Semiconductor integrated circuit die to alu
`minum nitride or other high thermal-conductivity heat SinkS
`may enhance high power performance. Hybrid packaging
`may further provide reduction of packaging inductance to
`enable higher power, higher frequency MOSFET operation.
`A system may further include fully shielded conductively
`cooled inductors containing ferrite, powdered-iron or other
`high magnetic permeability material.
`Some embodiments of a plasma System employ an
`H-bridge FET configuration in a frequency-variable RF
`amplifier, i.e. generator or RF converter, that may operate at
`or near a discrete frequency such as 13.56 MHz. (The
`H-bridge configuration employs Semiconductor Switches in
`groups of 4 in a circuit geometry Such as shown in FIG. 9.)
`Digital control is provided for various H-bridge parameters,
`for example, frequency, power, driver phase, driver bias,
`circuit protection and auto-calibration features.
`A close-coupled RF Supply may provide lower cost and
`greater reliability in part through integration of generator,
`controls and matching Systems into a single unit that
`includes no moving parts or external cabling. The System
`may match a capacitive load over a factor of six or more
`while requiring changes in frequency of less than 3.0%. The
`System may include Series and parallel output capacitors and
`inductors that reduce an apparent load impedance change
`and a FETswitch that electronically moves the center of the
`resonant frequency.
`The system may fit in a unit with dimension 2"x13"x4"
`or leSS Volume. High permeability-loaded planar-structure
`inductors may be used to reduce inductor size and maintain
`a high quality factor (Q) with minimum distance to conduc
`tive walls. Planar heat sinks may also provide RF current
`return or RF shielding for a matching network portion of the
`System.
`Accordingly, in a first aspect, the invention features an RF
`plasma generator. The RF plasma generator includes a
`55
`variable frequency RF generator, comprising an H-bridge
`and an RF output. The RF generator generates electromag
`netic radiation having a power. The RF plasma generator
`further includes a matching network that includes at least
`one variable impedance component.
`The matching network also includes a first port that is
`electromagnetically coupled to the output of the RF genera
`tor and a Second port. The RF plasma generator also includes
`a load that is electromagnetically coupled to the Second port
`of the matching network, and a plasma chamber for con
`taining a plasma having a power. The plasma chamber is
`electromagnetically coupled to the load and receives elec
`
`45
`
`50
`
`60
`
`65
`
`4
`tromagnetic radiation having a power from the load. Adjust
`ing at least one of the frequency of the RF generator and the
`variable impedance component in the matching network
`changes the power in the plasma.
`The load of the RF plasma generator may be reactive. The
`matching network may transform the impedance of the
`reactive load to a Substantially real impedance. The load
`may comprise an inductive load. The load may comprise a
`capacitive load.
`Adjusting at least one of the frequency of the RF genera
`tor and the variable impedance component in the matching
`network may Substantially match an impedance of the load
`to an output impedance of the RF generator. Adjusting may
`increase the power in the plasma.
`The matching network may have a Substantially resistive
`impedance, at a frequency of the electromagnetic radiation.
`The matching network may include a Series combination of
`an amplifier and a variable capacitance capacitor. The vari
`able capacitor may be electrically controllable.
`Further, the RF generator and the matching network are
`physically integrated in a device housing. The RF plasma
`generator may further include a Sensor that measures power
`delivered to the load.
`At least one of the frequency of the RF generator and the
`variable impedance component in the matching network
`may be adjusted in response to a measurement of the Sensor.
`At least one of the frequency of the RF generator and the
`variable impedance component in the matching network
`may be adjusted to minimize power reflected from the
`plasma. At least one of the frequency of the RF generator
`and the variable impedance component in the matching
`network may be adjusted to maximize power in the plasma.
`The plasma may have a power that is related to the power
`of the electromagnetic radiation that is coupled from the
`load to the plasma. The matching network may include
`Switching transistors.
`In a Second aspect, the invention features a method for
`Stabilizing a plasma The method includes generating elec
`tromagnetic radiation with an RF generator that includes an
`H-bridge, the electromagnetic radiation having a power that
`is related to a DC voltage applied to an RF generator bus.
`The method further includes coupling the electromagnetic
`radiation to a plasma, Sensing the power in the electromag
`netic radiation generated by the RF generator and adjusting
`the DC voltage applied to the RF generator buS in response
`to the Sensed power So as to maintain a Substantially constant
`power in the plasma.
`Sensing the power in the plasma may include measuring
`a Voltage and a current of the electromagnetic radiation. The
`power may be maintained Substantially constant with a time
`constant of less than 10 kHz.
`In a third aspect, the invention features a method for
`Stabilizing a plasma. The method includes generating elec
`tromagnetic radiation with an RF generator that includes an
`H-bridge, the electromagnetic radiation having a power that
`is related to a DC voltage applied to an RF generator bus.
`The method further includes coupling the electromagnetic
`radiation to a plasma, measuring an impedance of the load
`impedance and adjusting the DC voltage applied to the RF
`generator bus in response to the measured load impedance
`So as to maintain a Substantially constant power in the
`plasma.
`Sensing the change in the load impedance may include
`determining the rate of change of the power of the electro
`magnetic radiation with time.
`
`Page 23 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`S
`In a fourth aspect, the invention features a method for
`Stabilizing a plasma The method includes generating elec
`tromagnetic radiation with an RF generator that includes an
`H-bridge, the electromagnetic radiation having a power that
`is related to a DC voltage applied to an RF generator bus.
`The method further includes coupling the electromagnetic
`radiation to a plasma, Sensing a power of the plasma and
`adjusting the DC voltage applied to the RF generator bus in
`response to the Sensed power of the plasma So as to maintain
`a Substantially constant power in the plasma. Sensing the
`power of the plasma may include measuring optical radia
`tion emitted by the plasma
`In a fifth aspect, the invention features a method for
`Stabilizing a plasma. The method includes generating elec
`tromagnetic radiation with an RF generator that includes an
`H-bridge, the electromagnetic radiation having a power that
`is related to a DC voltage applied to an RF generator bus.
`The method further includes electromagnetically coupling
`the electromagnetic radiation to an impedance matching
`network, Sensing a power of the electromagnetic radiation
`propagating through the matching impedance, coupling the
`electromagnetic radiation to a plasma and adjusting the DC
`Voltage applied to the RF generator bus in response to the
`Sensed power of the electromagnetic radiation propagating
`through the matching impedance So as to maintain a Sub
`Stantially constant power in the plasma.
`In a Sixth aspect, the invention features a method for
`Stabilizing a plasma. The method includes generating elec
`tromagnetic radiation with an RF generator, coupling the
`electromagnetic radiation to a plasma, Sensing a power
`related to the power in the plasma and adjusting an output
`impedance of the RF generator, in response to the Sensed
`power related to the power in the plasma, to an impedance
`that maintains at least one plasma parameter at a Substan
`tially constant value.
`The power related to the power in the plasma may include
`a power generated by the RF generator. The impedance that
`maintains a Substantially constant power in the plasma may
`include a predetermined impedance. The power may be
`maintained Substantially constant with a time constant of
`less than 10 kHz.
`In a Seventh aspect, the invention features an RF plasma
`generator. The RF plasma generator includes an RF genera
`tor. The RF generator includes an H-bridge and an RF
`output.
`The RF generator generates electromagnetic radiation at a
`frequency. The RF plasma generator further includes a
`matching network having an impedance that is Substantially
`resistive at the frequency of the RF electromagnetic radia
`tion. The matching network includes a first port that is
`electromagnetically coupled to the output of the RF genera
`tor and a Second port.
`The RF plasma generator also includes a load that is
`electromagnetically coupled to the Second port of the match
`ing network and a plasma chamber for containing a plasma
`therein. The plasma chamber is electromagnetically coupled
`to the load. The RF generator may include a variable
`frequency RF generator.
`In a eighth aspect, the invention features an RF plasma
`generator. The RF plasma generator includes an RF genera
`tor including an RF Output that generates electromagnetic
`radiation at a frequency. The RF plasma generator also
`includes a matching network comprising a 3-port Solid State
`device that controls a change of a capacitance of a compo
`nent in the matching network, an impedance of the matching
`network being Substantially resistive at the frequency of the
`RF electromagnetic radiation.
`
`6
`The matching network includes a first port that is elec
`tromagnetically coupled to the output of the RF generator
`and a Second port. The RF plasma generator further includes
`a load that is electromagnetically coupled to the Second port
`of the matching network and a plasma chamber for contain
`ing a plasma therein. The plasma chamber is electromag
`netically coupled to the load.
`In a ninth aspect, the invention features an RF plasma
`generator. The RF generator includes an H-bridge and an RF
`output, and generates electromagnetic radiation having a
`power. The RF plasma generator further includes a matching
`network comprising a Series combination of an amplifier and
`a variable capacitance capacitor. The matching network
`includes a first port that is electromagnetically coupled to the
`output of the RF generator and a Second port.
`The RF plasma generator Further includes a load that is
`electromagnetically coupled to the Second port of the match
`ing network and a plasma chamber for containing a plasma
`having a power. The plasma chamber is electromagnetically
`coupled to the load, and receives electromagnetic radiation
`having a power from the load. Adjusting at least one of the
`frequency of the RF generator and the variable impedance
`component in the matching network changes the power in
`the plasma. The variable capacitance capacitor may be
`electrically controllable.
`In a tenth aspect, the invention features an RF plasma
`generator. The RF plasma generator includes a variable
`frequency RF generator including an RF output that gener
`ates an RF signal having a power. The RF plasma generator
`also includes a matching network comprising at least one
`variable impedance component and a 3-port Solid State
`device that controls a change of a capacitance of a compo
`nent in the matching network. The matching network
`includes a first port that receives the RF signal and a Second
`port.
`The RF plasma generator also includes a load that is
`electrically coupled to the Second port of the matching
`network and a plasma chamber for containing a plasma
`having a power. The plasma chamber is electromagnetically
`coupled to the load via the RF signal. Adjusting at least one
`of the frequency of the RF generator and the variable
`impedance component in the matching network changes the
`power in the plasma.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`The above and further advantages of this invention may
`be better understood by referring to the following descrip
`tion in conjunction with the accompanying drawings, in
`which like numerals indicate like Structural elements and
`features in various figures. The drawings are not necessarily
`to Scale, emphasis instead being placed upon illustrating the
`principles of the invention.
`FIG. 1a illustrates a prior art plasma processing System
`that includes a separate RF generator and matching network.
`FIG. 1b illustrates a prior art plasma processing System
`that includes a separate RF generator and matching network.
`FIG. 2 is a graph that illustrates the plasma power and
`resistance for an embodiment employing an H-bridge oscil
`lator System.
`FIG. 3a is a Schematic diagram that illustrates the cou
`pling of an antenna and a plasma.
`FIG. 3b is a schematic diagram that illustrates the cou
`pling of an antenna and a plasma.
`FIG. 4 is a graph that illustrates the reactive and resistive
`components of an input impedance of one embodiment.
`
`US 6,887,339 B1
`
`1O
`
`15
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`Page 24 of 33
`
`ADVANCED ENERGY INDUSTRIES INC.
`Exhibit 1012
`
`

`

`7
`FIG. 5 illustrates an oscilloscope display of a plasma
`response to a change in RF frequency (lower trace) and RF
`Voltage (upper trace).
`FIG. 6a illustrates an embodiment of a plasma processing
`System that includes a closely-coupled RF Supply according
`to the present invention.
`FIG. 6b illustrates an embodiment of a plasma processing
`System that includes a closely-coupled RF Supply according
`to the present invention.
`FIG. 7 is a block diagram that illustrates an embodiment
`of a plasma generation and control System according to the
`present invention.
`FIG. 8A and FIG. 8B illustrate an embodiment of an
`H-bridge control circuit for the RF converter of FIG. 7.
`FIG. 9 is a Schematic diagram of a plasma Supply System
`that includes a resistance Stabilization network, according to
`one embodiment of the invention.
`FIG. 10 is a schematic diagram that illustrates an embodi
`ment of a resistance Stabilization network.
`FIG. 11 is a block diagram that illustrates an embodiment
`of a RF plasma generator that includes DC power Supply
`control with two loops.
`FIG. 12 is a block diagram that illustrates data control
`flow in one embodiment of a RF plasma generator.
`FIG. 13a is a block diagram that illustrates an embodi
`ment of a plasma processing System that Supplies power to
`an antenna.
`FIG. 13b is a block diagram that illustrates an embodi
`ment of a plasma processing System that Supplies power to
`a chuck.
`FIG. 14 is a block diagram that illustrates an embodiment
`of a Smooth Switching match