( 12 ) United States Patent
`Van Zyl
`
`US 10,861,677 B2
`( 10 ) Patent No .:
`Dec. 8 , 2020
`( 45 ) Date of Patent :
`
`US010861677B2
`
`( 54 )
`
`( * ) Notice :
`
`INTER - PERIOD CONTROL SYSTEM FOR
`PLASMA POWER DELIVERY SYSTEM AND
`METHOD OF OPERATING THE SAME
`( 71 ) Applicant : Advanced Energy Industries , Inc. ,
`Fort Collins , CO ( US )
`( 72 ) Inventor : Gideon Johannes Jacobus Van Zyl ,
`Fort Collins , CO ( US )
`( 73 ) Assignee : Advanced Energy Industries , Inc. ,
`Fort Collins , CO ( US )
`Subject to any disclaimer , the term of this
`patent is extended or adjusted under 35
`U.S.C. 154 ( b ) by 0 days .
`( 21 ) Appl . No .: 16 / 028,131
`( 22 ) Filed :
`Jul . 5 , 2018
`( 65 )
`
`Prior Publication Data
`Jan. 10 , 2019
`US 2019/0013182 A1
`
`( 60 )
`
`Related U.S. Application Data
`Provisional application No. 62 / 529,963 , filed on Jul .
`7 , 2017 .
`( 51 ) Int . Ci .
`HO1J 37/32
`?03H 7/40
`( 52 ) U.S. CI .
`CPC .. HOIJ 37/32183 ( 2013.01 ) ; HOIJ 37/32128
`( 2013.01 ) ; HO3H 7/40 ( 2013.01 )
`( 58 ) Field of Classification Search
`None
`See application file for complete search history .
`
`( 2006.01 )
`( 2006.01 )
`
`( 56 )
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`6,633,017 B1 * 10/2003 Drummond
`6,700,092 B2 *
`3/2004 Vona , Jr.
`( Continued )
`FOREIGN PATENT DOCUMENTS
`
`HO1J 37/32009
`219 / 121.57
`HO1J 37/32082
`219 / 121.43
`
`TW
`TW
`TW
`
`1562189
`201719711
`1585814
`
`12/2016
`6/2017
`6/2017
`
`OTHER PUBLICATIONS
`International Searching Authority , International Search Report and
`Written Opinion , International Application No. PCT / US2018 /
`040930 , dated Nov. 1 , 2018 ( 16 pages ) .
`( Continued )
`Primary Examiner Amy Cohen Johnson
`Assistant Examiner Srinivas Sathiraju
`( 74 ) Attorney , Agent , or Firm — Neugeboren O'Dowd PC
`( 57 )
`ABSTRACT
`A generator produces output such as delivered power , volt
`age , current , forward power etc. that follows a prescribed
`pattern of output versus time where the pattern repeats with
`a repetition period by controlling sections of the pattern
`based on measurements taken one or more repetition periods
`in the past . A variable impedance match network may
`control the impedance presented to a radio frequency gen
`erator while the generator produces the output that follows
`the prescribed pattern of output versus time where the
`pattern repeats with a repetition period by controlling vari
`able impedance elements in the match during sections of the
`pattern based on measurements taken one or more repetition
`periods in the past .
`28 Claims , 9 Drawing Sheets
`
`301
`
`310
`
`312
`
`311
`
`?
`???
`ZN - 1
`
`300
`
`303 304
`
`305
`
`TS
`
`Ts
`
`313
`
`??
`KT
`
`?
`
`Tu
`
`306
`TS
`
`307
`
`ZOH
`
`352
`
`351
`
`354
`
`53
`
`K NTS
`ZN - 1
`
`Ts
`
`308
`
`309
`
`??
`
`355
`
`??
`
`356
`
`357
`
`358
`
`350
`
`P
`
`ZOH
`
`TS
`
`359
`
`+
`
`?
`
`k??
`
`302
`
`??
`
`NT , = T.
`
`RENO EXHIBIT 2022
`Advanced Energy v. Reno, IPR2021-01397
`
`

`

`US 10,861,677 B2
`Page 2
`
`( 56 )
`
`References Cited
`U.S. PATENT DOCUMENTS
`7,115,185 B1 * 10/2006 Gonzalez
`11/2010 Van Zyl et al .
`7,839,223 B2
`7,872,523 B2 *
`1/2011 Sivakumar
`8,576,013 B2 * 11/2013 Coumou
`5/2014 Rughoonundon
`8,736,377 B2 *
`8,773,019 B2 *
`7/2014 Coumou
`7/2015 Blackburn
`9,088,267 B2 *
`7/2015 Schatz
`9,093,853 B2 *
`9,210,790 B2 * 12/2015 Hoffman
`9,294,100 B2 *
`3/2016 Van Zyl
`9,355,822 B2 *
`5/2016 Yamada
`9,509,266 B2 * 11/2016 Coumou
`9,515,633 B1 * 12/2016 Long
`9,536,713 B2 *
`1/2017 Van Zyl
`9,544,987 B2 *
`1/2017 Mueller
`9,595,424 B2 *
`3/2017 Marakhtanov
`9,680,217 B2 *
`6/2017 Ali
`9/2017 Van Zyl
`9,773,644 B2 *
`9,812,305 B2 * 11/2017 Pelleymounter
`9,852,890 B2 * 12/2017 Mueller
`9,947,514 B2 * 4/2018 Radomski
`10,049,857 B2 *
`8/2018 Fisk , II
`10,109,460 B2 * 10/2018 Liu
`10,217,609 B2 *
`2/2019 Fisk , II
`2007/0107844 A1 *
`5/2007 Bullock
`
`HO1J 37/321
`156 / 345.44
`HO3F 3/2176
`330/10
`HO3F 3/191
`330/305
`HO3K 4/026
`330/296
`HO3F 1/0211
`315 / 111.21
`HO1J 37/32183
`BOOL 53/12
`HO5H 1/46
`HO1J 37/32155
`C23C 16/515
`HO3F 1/0211
`HO3H 7/38
`HO1J 37/32935
`HO1J 37/32155
`HO1J 37/32183
`H01Q 3/267
`HO1J 37/32155
`HO1J 37/3476
`HO1J 37/32155
`HO1J 37/32091
`HO1J 37/32174
`HO1J 37/3299
`HO1J 37/32935
`HO1J 37/32082
`156 / 345.28
`
`2010/0026186 A1 *
`
`2/2010 Forrest
`
`2010/0171427 A1 *
`
`7/2010 Kirchmeier
`
`2010/0270141 A1 * 10/2010 Carter
`
`2010/0276273 A1 * 11/2010 Heckman
`
`2011/0248633 A1 * 10/2011 Nauman
`
`2013/0169359 Al
`2014/0239813 A1
`2015/0162168 A1 *
`
`7/2013 Coumou
`8/2014 Van Zyl et al .
`6/2015 Oehrlein
`
`6/2016 Fisk , II
`2016/0163514 A1 *
`9/2016 Van Zyl
`2016/0276138 A1
`1/2017 Zeine et al .
`2017/0005533 Al
`3/2017 Radomski
`2017/0062187 Al *
`2017/0310008 A1 * 10/2017 White
`2017/0365907 A1 * 12/2017 Kapoor
`2018/0167043 A1 *
`6/2018 Van Zyl
`2019/0013182 A1 *
`1/2019 Van Zyl
`
`HO1J 37/32045
`315 / 111.21
`GO1R 21/06
`315 / 111.21
`HO1J 37/32935
`204/164
`C23C 16/509
`204 / 192.11
`C23C 14/3485
`315 / 111.21
`
`HO1J 37/32146
`438/694
`HO1J 37/32174
`315 / 111.21
`
`HO1J 37/321
`HO3H 7/40
`???? 7/40
`HO3F 3/265
`HO3H 7/40
`
`OTHER PUBLICATIONS
`International Searching Authority , International Search Report and
`Written Opinion , issued for International Application No. PCT /
`US2019 / 020286 , dated Jun . 5 , 2019 ( 14 pages ) .
`TIPO ,
`“ Official Action From the Intellectual Property Office of
`Taiwan Regarding Application No. 107123277 ” , dated Jul . 8 , 2020 ,
`p . 19 , Published in : TW .
`* cited by examiner
`
`

`

`U.S. Patent
`
`Dec. 8 , 2020
`
`2
`
`Sheet 1 of 9
`
`US 10,861,677 B2
`
`101
`
`102
`
`103
`
`104
`
`105
`
`106
`
`+
`
`?
`
`?
`
`k
`S
`
`?
`
`P
`
`V
`
`100
`
`?? S
`
`151
`
`?
`
`157
`
`+
`
`152
`3
`
`e ?
`
`?
`
`TS
`
`FIG . 1A
`
`153
`
`154
`
`158
`
`155
`
`?
`
`KTS
`Z - 1
`
`?
`
`?
`
`150
`
`156
`
`ZOH
`
`Ts
`
`FIG . 1B
`
`159
`
`

`

`U.S. Patent
`
`Dec. 8. 2020
`
`2
`
`Sheet 2 of 9
`
`US 10,861,677 B2
`
`200
`
`250
`
`Set Point /
`Output Power
`
`6
`
`4
`
`2
`
`1
`
`0
`
`201 .
`
`202
`
`Relatively slow system .
`
`Input
`Output
`Point A
`
`203
`
`T :
`
`205
`
`1
`
`1.2
`
`2
`
`204
`
`Relative influence of input on point A
`
`1.4
`
`1.6
`
`2
`
`1
`
`1
`
`1.2
`Time ( ms )
`FIG . 2A
`
`Relatively fast system .
`
`251
`
`Set Point /
`Output Power
`
`252
`
`253
`
`2
`
`15
`
`1
`
`0.5
`
`1
`
`1.2
`
`254
`vi
`
`Input
`Output
`Point A
`
`us
`
`Relative influence of input on point A
`
`0.4
`
`0.6
`
`0.8
`
`1
`
`1.2
`Time ( ms )
`
`FIG . 2B
`
`2
`
`2
`
`

`

`U.S. Patent
`
`Dec. 8 , 2020
`
`?
`
`Sheet 3 of 9
`
`US10,861,677 B2
`
`301
`
`305
`
`T.
`
`TS
`
`310
`
`M
`
`311
`
`?
`
`k T ,
`zN.
`
`, T
`??
`T
`313
`K'p
`z1
`
`€
`
`?
`
`312
`
`? f
`61
`
`C ?
`
`To
`
`+
`
`?
`
`k To
`z ' - 1
`
`CN
`
`302
`
`T ,
`
`303 304
`
`?
`
`X
`
`300
`
`308
`
`?
`
`P
`
`309
`
`?
`
`|
`
`306
`Ts
`
`307
`
`?
`
`ZOH
`
`NT , -To
`
`FIG . 3A
`
`352
`
`351
`
`354
`
`353
`
`355
`
`356
`
`357
`
`358
`
`350
`
`x
`
`TS
`
`?
`
`[ k NT ,
`zN.
`
`P
`
`ZOH
`
`Ts
`
`359
`
`FIG . 3B
`
`

`

`U.S. Patent
`
`Dec. 8 , 2020
`
`2
`
`Sheet 4 of 9
`
`US 10,861,677 B2
`
`Input
`Output
`
`401 1444
`
`2
`
`Inter - period control
`
`400
`
`197
`
`4
`
`6
`
`8
`
`9
`
`FIG . 4A
`
`402
`
`Input
`Output
`
`2
`
`403
`
`404
`
`30
`
`30.2
`
`30.4
`
`30.6
`
`30.8
`Time ( ms )
`
`31.2
`
`Inter - period control
`
`Input
`Output
`O Point A
`Points influencing
`X point A
`
`??????
`
`2
`
`0
`
`1
`
`2
`
`7
`
`8
`
`451
`
`1
`
`0.5
`
`-0.5
`
`0 Relative influence of input on point A
`
`????????????
`
`2
`
`3
`
`4
`
`5
`Time ( ms )
`
`FIG . 4B
`
`450
`
`FIG . 4C
`
`FIG . 4D
`
`

`

`U.S. Patent
`
`Dec. 8 , 2020
`
`?
`
`Sheet 5 of 9
`
`US10,861,677 B2
`
`501
`
`?
`
`X
`
`500
`
`503
`
`504
`
`506
`
`507
`
`508
`
`509
`
`e
`
`?
`
`Weke NT 2+ Wakatsz **
`1 - W , z'.W , z1
`
`P
`
`ZOH
`
`502
`
`T ,
`
`Te
`
`S
`
`510
`
`505
`
`c ( n ) = W [ c ( n - N ) + k2NT , e ( n - N ) ]
`+
`Wo [ c'n - 1 ) + k
`
`? [ ( 1 - Te ( n
`
`
`FIG . 5
`
`

`

`U.S. Patent
`
`Dec. 8 , 2020
`
`2
`
`Sheet 6 of 9
`
`US 10,861,677 B2
`
`Loop gain .
`
`Nyquist plot of loop gain . Magnitude compressed by log , [ 1 + log , ( 1 + - ) ]
`
`40
`
`Magnitude ( 08 )
`
`26
`
`100
`
`101
`
`102
`
`103
`
`4
`
`109
`
`105
`
`4
`
`3
`
`2
`
`-2
`
`
`
`Imaginary part
`
`10
`
`102
`Frequency ( Hz )
`FIG . 6A
`
`3
`
`-2
`
`wwwwwwwwwwww
`4
`5
`
`***
`
`1
`
`Real part
`FIG 6B
`
`Closed loop response .
`wwwwwww
`
`Closed loop response at and + - 1 Hz from harmonics .
`
`0.02
`
`
`
`1111111110IITTY11111111111111111IRF1111731331 } { ( TTTTTTT71
`
`
`
`
`
`0
`
`Magnitude ( dB )
`
`-0.02
`
`-500
`Angle ( deg )
`
`-1000
`
`-500
`
`Magnitude ( dB )
`
`700
`* 104
`
`Angle ( deg )
`
`4 .
`
`" " F 177
`
`"
`
`
`
`102
`
`103
`
`?
`
`**** * 777774
`F
`
`
`
`104
`
`0.06
`
`105
`
`20
`
`30
`
`-0.04 G3121 * 11 * 1 *******
`
`* 1 * !
`
`
`
`
`
`: 1111 ( 1131381111111111111110111111111111111111
`
`
`
`
`
`
`
`
`
`TYTTI --------- T ***
`
`101
`
`111111111111111111111111111111111111111111111111111111111111111111 )
`
`Angle ( deg )
`
`0
`
`( 11361111311111111111111111111111111111111011 $ 3411111110111111111111111111 * )
`
`( 110111111111111111111111111111111111111111111111111111111111111133 }
`
`107
`
`107
`Frequency ( Hz )
`FIG . 6C
`
`104
`
`105
`
`20
`
`30
`
`120
`
`Frequency ( kHz )
`FIG . 6D
`
`

`

`U.S. Patent
`
`Dec. 8 , 2020
`
`2
`
`Sheet 7 of 9
`
`US 10,861,677 B2
`
`Loop gain .
`
`Nyquist plot of loop gain . Magnitude compressed by log , [ 1 + log , ( 17. ) ]
`
`20
`
`Magnitude ( dB )
`0
`
`100
`
`02
`
`103
`
`2.5
`
`1
`
`
`
`imaginary part
`
`M -2
`
`Angle ( deg )
`
`100
`
`Magnitude ( dB )
`
`-40
`100
`
`Angle ( deg )
`
`103
`Frequency ( Hz )
`FIG . 7A
`
`106
`
`-2
`
`1
`Real part
`
`?
`
`4
`
`FIG . 7B
`
`Closed loop response .
`
`Closed loop response at and +/- 1 Hz from harmonics .
`
`? M
`
`192
`
`103
`
`104
`
`105
`
`Magnitude ( dB )
`10
`
`- 15
`
`Angle ( deg )
`
`80
`
`100
`
`120
`
`104
`
`105
`
`-100
`
`20
`
`SWITTER
`
`:
`
`HTTSTYR
`ao
`100
`
`120
`
`Frequency ( kHz )
`
`FIG . 7D
`
`- -
`
`~ - ~~ - ~~~ -???
`
`M
`
`0
`
`102
`Frequency ( Hz )
`
`FIG . 70
`
`

`

`U.S. Patent
`
`Dec. 8 , 2020
`
`2
`
`Sheet 8 of 9
`
`US 10,861,677 B2
`
`Loop gain .
`
`Nyquist plot of loop gain . Magnitude compressed by log , [ 1 + log ( 1 + . ) ]
`
`40
`
`Magnitude ( dB )
`
`20
`
`0
`
`-20
`
`lum
`
`100
`
`101
`
`102
`
`COM
`
`104
`
`105
`
`1
`
`0.5
`
`0
`
`
`
`Imaginary part
`
`???
`
`Angle ( deg )
`-50
`
`-150 of
`
`Magnitude ( dB )
`-20
`
`Angle ( deg )
`
`- 100
`
`- 150
`
`r ?? ???? ??
`
`??? -r -- r -
`
`?? »
`
`102
`Frequency ( Hz )
`
`FIG . 8A
`
`105
`
`-3
`
`-2
`
`2
`
`3
`
`0
`
`1
`Real part
`FIG . 8B
`
`Closed loop response .
`
`Closed loop response at and + - 1 Hz from harmonics .
`
`101
`
`102
`
`104
`
`105
`
`Magnitude ( 0B )
`
`o :
`
`-20
`
`
`
`Angle deg )
`- 100
`
`101
`
`102
`Frequency ( Hz )
`
`HU
`
`106
`
`-150
`0
`
`20
`
`FIG . 8C
`
`20
`
`Birt19
`100
`
`120
`
`TETTE : (
`
`TEST
`
`80
`
`100
`
`120
`
`Frequency ( kHz )
`
`FIG . 8D
`
`

`

`U.S. Patent
`
`Dec. 8 , 2020
`
`2
`
`Sheet 9 of 9
`
`US 10,861,677 B2
`
`901
`
`X1
`X2
`
`XM
`
`900
`
`904
`
`Ci
`C2
`
`905
`
`906
`
`902
`
`903
`
`Controller
`
`CO +
`
`?
`
`P
`
`907
`
`.
`
`y
`Y2
`
`T
`
`S
`
`910
`
`??
`
`ZOH
`
`908
`
`d
`d
`
`do
`
`TS
`
`909
`
`Memory
`
`FIG . 9
`
`

`

`US 10,861,677 B2
`
`2
`It is with these observations in mind , among others , that
`aspects of the present disclosure were conceived .
`
`1
`INTER - PERIOD CONTROL SYSTEM FOR
`PLASMA POWER DELIVERY SYSTEM AND
`METHOD OF OPERATING THE SAME
`
`5
`
`SUMMARY
`CROSS - REFERENCE TO RELATED
`According to one embodiment , a generator produces
`APPLICATION
`output such as delivered power , voltage , current , forward
`power etc. that follows a prescribed pattern of output versus
`This application is related to and claims priority under 35
`time where the pattern repeats with a repetition period by
`U.S.C. § 119 ( e ) from U.S. Patent Application No. 62/529 ,
`963 , filed Jul . 7 , 2017 entitled “ INTER - PERIOD CON- 10 controlling sections of the pattern based on measurements
`taken one or more repetition periods in the past . In one
`TROL SYSTEM FOR PLASMA POWER DELIVERY
`example , a power delivery system involves a generator that
`SYSTEM AND METHOD OF OPERATING THE SAME , ”
`produces a repeating output pattern and a control element
`the entire contents of which is incorporated herein by
`controls the repeating pattern based on a measurement of a
`reference for all purposes .
`15 value of the repeating pattern taken a period prior to a
`current period . The control element may further control the
`TECHNICAL FIELD
`repeating output pattern based on the measurement of the
`repeating pattern taken a period prior to the current period
`Aspects of the present disclosure relate to improved
`combined with a measurement of a value of the repeating
`methods and systems for controlling a power delivery sys- 20 pattern during a current period . The repeating output pattern
`tem , and particularly for controlling a plasma power deliv-
`may follow a prescribed pattern of output versus time
`wherein the prescribed pattern repeats with a repetition
`ery system .
`period , and wherein the measurement of the value of the
`BACKGROUND
`repeating pattern taken a period prior to the current period
`25 occurs one or more repetition periods in the past .
`According to yet another embodiment , a variable imped
`Plasma processing systems are used to deposit thin films
`ance match network controls the impedance presented to a
`on a substrate using processes such as chemical vapor
`RF generator while the generator produces output , such as
`deposition ( CVD ) and physical vapor deposition ( PVD ) as
`delivered power , voltage , current , forward power , etc. , that
`well to remove films from the substrate using etch processes .
`The plasma is often created by coupling radio frequency 30 follows a prescribed pattern of output versus time where the
`( RF ) or direct current ( DC ) generators to a plasma chamber
`pattern repeats with a repetition period by controlling vari
`filled with gases injected into the plasma chamber at low
`able impedance elements in the match during sections of the
`pressure . Typically , a generator delivers RF power to an
`pattern based on measurements taken one or more repetition
`antenna in the plasma chamber , and power delivered at the
`periods in the past . The generator may provide the delivered
`antenna ignites and sustains a plasma . In some instances , the 35 power , voltage , current , forward power , etc. , to a plasma
`RF generator is coupled to an impedance matching network
`system in order to ignite and sustain a plasma , in various
`that may match the plasma impedance to a desired imped-
`possible embodiments .
`ance , typically 502 , at the generator output . DC power is
`According to yet another embodiment , a generator pro
`typically coupled to chamber via one or more electrodes .
`duces output that follows a prescribed pattern of output
`The generator alone or the generator in combination with 40 versus time where the pattern repeats with a repetition
`other pieces of equipment , such as the impedance matching
`period by controlling sections of the pattern based on
`network , other generators coupled to the same plasma ,
`measurements taken one or more repetition periods in the
`cables , etc. , constitute a plasma power delivery system .
`past ; and combining this controller with an intra - period
`Modulation of the power delivered to the plasma system
`controller that calculates the control output based on mea
`is often required . Most modulation schemes are repetitive , 45 surements taken less than a repetition period in the past .
`i.e. , the same modulation waveform is repeated at a wave-
`According to yet another embodiment , a variable imped
`form repetition rate . The associated waveform repetition
`ance match network controls the impedance presented to a
`period is equal to one divided by the waveform repetition
`RF generator while the generator produces output , such as
`rate . The ability to follow a prescribed modulation wave-
`delivered power , voltage , current , forward power , etc. , that
`form using a traditional control scheme requires high band- 50 follows a prescribed pattern of output versus time where the
`width from the controller and ultimately from the measure-
`pattern repeats with a repetition period by controlling vari
`ment system . Many plasma systems have power applied to
`able impedance elements in the match during sections of the
`the plasma at different frequencies . The nonlinear nature of
`pattern based on measurements taken one or more repetition
`the plasma load creates intermodulation products that can
`periods in the past ; and combining this controller with an
`interfere with a generator's measurements system . Thus , it is 55 intra - period controller that calculates the control of the
`sometimes advantageous to use a narrowband measurement
`variable impedance elements in the match based on mea
`system to limit such interference . In many applications ,
`surements taken less than a repetition period in the past .
`power delivered to the plasma load is not the only parameter
`According to another embodiment , a generator produces
`that is being controlled . For example , in RF power delivery
`output that follows a prescribed pattern of output versus time
`systems , the impedance presented to the generator by the 60 where the pattern repeats with a repetition period by con
`plasma load can be controlled , either through controlling the
`trolling sections of the pattern based on measurements taken
`frequency of the generator output or through controlling a
`one or more repetition periods in the past while at the same
`variable impedance match network between the generator
`time adjusting another parameter such as generator output
`and the plasma load . In some cases , generator source imped-
`frequency or variable impedance elements contained in the
`ance may also be controlled . Tracking and controlling power 65 generator or in a variable impedance matching network
`in light of these various issues presents ever greater control
`coupled between the generator and the plasma based on
`challenges .
`measurements taken one or more repetition periods in the
`
`

`

`US 10,861,677 B2
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`15
`
`3
`4
`waveform for the combined inter - period and intra - period
`past where the correlation between the control inputs such as
`controller related to FIG . 7A .
`power control and generator frequency and control outputs
`FIG . 8A illustrates the loop gain as a function of fre
`such as delivered power and impedance presented to the
`quency of an example combined inter - period and intra
`generator is determined and used by the control system .
`According to yet another embodiment , a generator pro- 5 period controller with a 0.01 weighting for the inter - period
`duces output that follows a prescribed pattern of output
`part and a 0.99 weighting for the intra - period part .
`versus time where the pattern repeats with a repetition
`FIG . 8B illustrates the Nyquist plot of the loop gain for the
`period by controlling a section of the pattern based on
`combined controller related to FIG . 8A .
`measurements taken for the same section one or more
`FIG . 8C illustrates the closed loop response as a function
`repetition periods in the past ; as well as such measurements 10 of frequency for the combined controller related to FIG . 8A .
`for other sections in the pattern by perturbing the control
`FIG . 8D illustrates the closed loop response as a function
`input , determining the response to the perturbation , and
`of frequency at and close to the harmonics of the input
`using the response to the perturbation to compensate for
`waveform for the same combined inter - period and intra
`coupling between adjacent or closely located time periods in
`period controller related to FIG . 8A .
`FIG . 9 illustrates a block diagram of a multi - input multi
`the waveform .
`output version of a combined inter - period and intra - period
`controller according to one embodiment of the present
`BRIEF DESCRIPTION OF THE DRAWINGS
`disclosure .
`The various features and advantages of the technology of
`the present disclosure will be apparent from the following 20
`DETAILED DESCRIPTION
`description of particular embodiments of those technologies ,
`Embodiments of the present disclosure provide a plasma
`as illustrated in the accompanying drawings . It should be
`power delivery system that produces an output , such as
`noted that the drawings are not necessarily to scale ; however
`delivered power , voltage , current , and forward power , that
`the emphasis instead is being placed on illustrating the
`principles of the technological concepts . Also , in the draw- 25 follows a prescribed pattern of output versus time where the
`ings the like reference characters may refer to the same parts
`pattern repeats with a repetition period by controlling sec
`throughout the different views . The drawings depict only
`tions of the pattern based on measurements taken one or
`typical embodiments of the present disclosure and , there-
`more repetition periods in the past as opposed to within the
`current period . Compared to a conventional controller , such
`fore , are not to be considered limiting in scope .
`FIG . 1A illustrates a simple analog intra - period , and FIG . 30 an inter - period controller can reproduce output more accu
`1B illustrates a simple digital intra - period control systems
`rately utilizing a lower bandwidth measurement and control
`that may be used to control a plasma power delivery system .
`system . The benefits provided by the inter - period controller
`FIG . 2A illustrates the response of a relatively slow
`can be advantageous in various contexts including in the
`intra - period control system to a periodic input and FIG . 2B
`presence of plasma generated mixing and intermodulation
`illustrates the response of a relatively fast intra - period 35 products . In additional embodiments , the inter - period con
`control system to a periodic input .
`troller can be combined with a conventional intra - period
`FIG . 3A and FIG . 3B illustrate block diagrams of example
`controller . In additional embodiments , parameters , such as
`inter - period controllers that may be implemented in a
`generator output frequency , may be adjusted together with
`plasma power delivery system according to embodiments of
`the main output based on measurements taken one or more
`the present disclosure .
`40 repetition periods in the past where the correlation between
`FIG . 4A - FIG . 4D illustrate the response of an example
`the control inputs , such as power control and generator
`inter - period controller to a periodic input .
`frequency , and control outputs , such as delivered power and
`FIG . 5 illustrates a block diagram of an example com-
`impedance presented to the generator are determined and
`bined inter - period and intra - period controller that may be
`used by the control system . In additional embodiments , a
`implemented in a plasma power delivery system according 45 generator produces output that follows a prescribed pattern
`of output versus time where the pattern repeats with a
`to one embodiment of the present disclosure .
`FIG . 6A illustrates the loop gain as a function of fre-
`repetition period by controlling a section of the pattern based
`quency of an example pure inter - period controller .
`on measurements taken for the same section one or more
`FIG . 6B illustrates the Nyquist plot of the loop gain for the
`repetition periods in the past ; as well as such measurements
`inter - period controller generating the loop gain of FIG . 6A . 50 for other sections in the pattern by perturbing the control
`FIG . 6C illustrates the closed loop response as a function
`input , determining the response to the perturbation , and
`of frequency for the inter - period controller generating the
`using the response to the perturbation to compensate for
`coupling between adjacent or closely located time periods in
`loop gain of FIG . 6A .
`FIG . 6D illustrates the closed loop response as a function
`the waveform .
`of frequency at and close to the harmonics of the input 55
`While primarily described with reference to a controller
`for a generator , aspects of the present disclosure are appli
`waveform for the pure inter - period controller .
`FIG . 7A illustrates the loop gain as a function of fre-
`cable to switch mode power supplies , and controllers for the
`quency of an example combined inter - period and intra-
`same , which may be used in eV source applications such as
`period controller with a 0.1 weighting for the inter - period
`to provide a bias to a substrate as part of an overall power
`part and a 0.9 weighting for the intra - period part .
`60 delivery system , as well as other substrate biasing schemes .
`FIG . 7B illustrates the Nyquist plot of the loop gain
`The controller and control schemes discussed herein may
`also be used to control variable impedance elements ( such as
`related to FIG . 7A .
`FIG . 7C illustrates the closed loop response as a function
`vacuum variable capacitors or switched variable reactance
`elements ) of impedance matching networks . In such
`of frequency of the example combined controller related to
`65 instances , aspects of the present disclosure may or may not
`FIG . 7A .
`FIG . 7D illustrates the closed loop response as a function
`also be used in the controlling of an RF supply to the
`impedance matching network as part of the overall power
`of frequency at and close to the harmonics of the input
`
`

`

`US 10,861,677 B2
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`5
`6
`254 shows that the point A , 253 , is now even more heavily
`delivery system . The controller may reside in any part of the
`influenced by the input in the very recent past .
`power delivery system ( e.g. , in the generator or in the
`In these conventional intra - period controllers , the error
`matching network ) and may or may not receive information
`control is based on the measured value of the current output
`from and control other parts of the power delivery system .
`For example , a controller residing in the generator may 5 ( within the period ) against the set point . So , referring to FIG .
`control both a generator and a match that are part of the
`2A , for example , the measured value of the output at time
`power delivery system with information obtained only from
`1.5 ms would be compared against the set point value at that
`the generator , only from the match or from both the gen
`same time to generate the error signal . Stated differently , the
`erator and the match . The controller and control schemes
`set point values are compared against the measured values
`discussed herein may also be used in other systems with or 10 during the current period to generate the error signal for the
`without delivering power in a plasma power delivery envi
`conventional intra - period controller . In contrast , an inter
`ronment .
`period controller compares the measured value of the output
`FIG . 1A ( prior art ) illustrates a simple analog intra - period ,
`one or more cycles in the past for a given set point and uses
`and FIG . 1B ( prior art ) illustrates a simple digital intra
`period control systems that may be used to control a plasma is the past measured value at the set point to generate the
`power delivery system . In FIG . 1A the difference between an
`current error signal and controller output . Referring again to
`input 101 and output 106 produces an error signal 102 that
`FIG . 2A , for example , at time 1.5 ms with a set point of 3 ,
`the measured value at time 0.94 ms ( which is one waveform
`a controller 103 uses to produce a control input 104 to a plant
`105. In this illustration , the controller is a simple integrator
`repetition period of 0.56 ms earlier or that part of the
`with a gain of k . In an actual implementation , the control 20 preceding pulse that correlates with time 1.5 ms ) with the
`input 104 , c , may be a drive level to a power amplifier , and
`same set point of 3 would be used by the controller to
`the plant 105 , P , a power amplifier . To illustrate the perfor-
`generate the error and output , as opposed to the measured
`mance differences between this controller and the disclosed
`value within the pulse at time 1.5 ms . Notably , the inter
`inter - period controller , the plant 105 , P , is a unity gain block ,
`period controller need not be nearly as fast because it relies
`i.e. y = c . With these assumptions , the loop gain has unity gain 25 on a measured value one cycle in the past as opposed to an
`at k rad / s or k / ( 2T ) Hz , the time constant of the system step
`immediately proximate value within the pulse .
`response is 1 / k s and the integral of the impulse response of
`In some examples , the pulse ( e.g. , the pulse over period
`the system reaches 63.2 % ( 1-1 / e ) in 1 / k s . In FIG . 1B , an
`Tp ) is divided into multiple time periods , and the corre
`input 151 is sampled at a sampling rate of 1 / T , and digitized
`sponding ( same ) output value in the same time period of the
`by a sampler 157. ( In some applications the input is already 30 previous pulse is used for the error signal . Referring again
`a digital data stream and the sampler 157 is not present in the
`to the example immediately above referring to using the
`system . ) The output 156 is sampled and digitized by a
`measured value at time 0.94 ms of the first pulse for the error
`sampler 159 and the difference between the input and output
`correction at time 1.5 ms of the following second pulse , the
`produces an error signal 152 that a controller 153 uses to
`time period would encompass the specific value of 0.56 ms
`produce a control input 154 which is converted to an analog 35 within some range . In one example , the time periods by
`control signal by a digital to analog converter 158 which is
`which pulses are divided are such that any given time period
`fed to a plant 155. As for FIG . 1A , to illustrate the perfor-
`does not encompass different set points , with the exception
`mance differences between this controller and the disclosed
`of sloped set point transitions .
`inter - period controller , the plant 105 , P , is a unity gain block .
`In various implementations , the inter - period pulse infor
`The same statements regarding relationship between k and 40 mation is stored in some form of memory such that it can be
`the unity gain frequency and response times hold as for the
`accessed and used by the controller for the error feedback of
`analog controller of FIG . 1A provided that k is much less
`the succeeding pulse . Complicated pulses , such as with
`sloped set point transitions , and otherwise different set
`than 2./T ,
`FIG . 2A ( prior art ) shows the response 200 of the simple
`points may benefit from relatively smaller time period
`intra - period controller such as shown in FIG . 1A or FIG . 1B 45 subdivisions of the pulse , and therefore may require rela
`to a periodic input with period T » , 205. In this example a
`tively larger and faster memory . In specific examples , pulses
`host of different set points ( e.g. , a set point power of 1 ,
`with between a 100 ms and 10 us period Tp may be
`followed by 2 , followed by 5 , with a ramp to 3 ) defines one
`subdivided into 1024 time slices , and output values for each
`period of the input . The output , 202 , follows the input , 201
`slice stored for comparison to the measured valued in the
`with visible inaccuracy ( where the output does not match the 50 same time slice of the subsequent pulse .
`input set point ) . The time constant of the closed loop
`In some applications no error signal is generated . In
`response for this illustration is 10 The output at a given
`impedance matching applications using an inter - period con
`point , A , 203 , can be obtained by multiplying the time
`trol scheme information about an impedance presented to a
`shifted time reversed impulse response of the system with
`generator one or multiple periods , Tp , 205 , in the past can be
`the input and integrating . The normalized time shifted time 55 used to adjust variable impedance elements within the
`reversed impulse response of the unit , 204 , shows that the
`matching network at the present time . The information can
`output at point A , 203 , is heavily influenced by the very
`be used to calculate adjustments to the variable impedance
`recent past ( within one time constant or 10 us prior to point
`matching elements without first generating an error signal .
`A ) , and almost not at all by events occurring earlier than 10
`In impedance matching applications the setpoint ( e.g. 101 ,
`time constants prior to point A. To accommodate the chang- 60 151 , 303 , 351 , 501 ) is generally constant , but there is a
`ing set points within a pulse , the conventional controller
`periodic disturbance of the load impedance that must be
`must be very fast . As shown in FIG . 2B ( prior art ) , speeding
`matched to a desired input impedance . Such a periodic
`up the controller improves the ability of the output to follow
`disturbance can for example arise from delivering power to
`the input accurately . The time constant of the closed loop
`a plasma load that follows a prescribed pattern of output
`response