USOO9243.316B2(12) United States Patent(10) Patent No.:

(54)

(56)

METHOD OF FABRICATINGPIEZOELECTRIC MATERAL WITH
SELECTED C-AXIS ORIENTATION

Jan. 26, 2016

References Cited
U.S. PATENT DOCUMENTS

3,174,122 A
3,189,851 A(75) Inventors: John Larson, III, Palo Alto, CA (US);Sergey Mishin, Goleta, CA (US)(73) Assignee: Avago Technologies General IP(Singapore) Pte. Ltd., Singapore (SG)(*) Notice:

US 9.243,316 B2(45) Date of Patent:

Larson, III et al.

3, 1965 Fowler et al.
6, 1965 Fowler(Continued)
FOREIGN PATENT DOCUMENTS
CN
DE

Subject to any disclaimer, the term of thispatent is extended or adjusted under 35
U.S.C. 154(b) by 909 days.

1.0117O303
1023.9317

4/20083, 2004(Continued)
OTHER PUBLICATIONS(21) Appl. No.: 12/692,108

Chen, “Fabrication and Characterization of ALN Thin Film Bulk

(22) Filed:

Acoustic Wave Resonator” Dissertation, University of Pittsburgh
School of Engineering, 2006.

Jan. 22, 2010(65)

US 2011 FO18O391 A1

(51)

(52)

(Continued)

Prior Publication Data

Int. C.
C23C I4/34
C23C I4/06
C23C I4/00
C23C I4/02
C23C I4/22
HO3H3/007
U.S. C.

Primary Examiner — Jason MBerman

Jul. 28, 2011(57)

In accordance with a representative embodiment, a method of
fabricating a piezoelectric material comprising a first compo
nent and a second component comprises: providing a Sub
strate; flowing hydrogen over the substrate; flowing the firstcomponent to form the piezoelectric material over a target;and sputtering the piezoelectric material from the target on
the Substrate. In accordance with another representative
embodiment, a method of fabricating a bulk acoustic wave
(BAW) resonator comprises: forming a first electrode over a
Substrate; forming a seed layer over the Substrate; and depos
iting a piezoelectric material having a compression-negative(C) polarity. The depositing of the piezoelectric material
comprises: flowing a first component of the piezoelectricmaterial to form the piezoelectric material over a target com
prising a second component of the piezoelectric material; andsputtering the piezoelectric material from the target to the(2006.01)(2006.01)(2006.01)(2006.01)(2006.01)(2006.01)

CPC ......... C23C 14/0617 (2013.01); C23C 14/0036(2013.01); C23C 14/02 (2013.01); C23C
14/022 (2013.01); C23C 14/0641 (2013.01);
C23C 14/228 (2013.01); C23C 14/345(2013.01); H03H 2003/0071 (2013.01)(58)

ABSTRACT

Field of Classification Search

CPC .............. C23C 14/0641; C23C 14/228; C23C

14/0617: C23C 14/02: C23C 14/0036

substrate.

USPC ........................... 204/192.12, 192.15, 192.18

See application file for complete search history.

23 Claims, 10 Drawing Sheets
401

412

US 9.243,316 B2Page 2(56)

References Cited

5,853,601 A

12/1998 Krishnaswamy et al.

U.S. PATENT DOCUMENTS

5,864,261 A
5,866,969 A
5,872,493 A

1, 1999 Weber
2f1999 Shimada et al.
2, 1999 Ella

3,321,648 A

5, 1967 Kolm

5,873,153 A

2/1999 Ruby et al.

3.422,371 A

3,568,108 A
3,582,839 A
3,590,287 A

1/1969 Poirier et al.

3, 1971 Poirier et al.
6, 1971 Pim et al.
6, 1971 Berlincourt et al. .......... 310,321

5,873,154 A

5,894, 184 A
5,894,647 A
5,910,756 A

2/1999 Ylilammi et al.

4/1999 Furuhashi et al.
4/1999 Lakin6, 1999 Ella

3,610,969 A

10/1971 Clawson et al.

5,932,953 A

8/1999 Drees et al.

3,845,402 A

10/1974 Nupp

5,953,479 A

9, 1999 Zhou et al.

4,084.217. A

4, 1978 Brandli et al.

5,955,926 A

9/1999 Uda et al.

4,172.277 A

10, 1979 Pinson

5,962,787 A

10, 1999 Okada et al.

4,320,365. A

1 1/1980 Black et al.

5,969,463 A

1 1/1999 Tomita

4,272,742 A

6, 1981 Lewis

5,982,297 A

1 1/1999 Welle
12/1999 Swirhun et al.

3,826,931 A

7, 1974 Hammond

5,936,150 A

8, 1999 Kobrin et al.

4,281.299 A

7, 1981 Newbold

6,001,664 A

4,344,004 A

8, 1982 Okubo

6,016,052 A

1/2000 Vaughn

4,355.408 A

10, 1982 Scarrott

6,040,962 A

3/2000 Kanazawa et al.

4.419,202 A * 12/1983 Gibson .................... 204,192.16
4,456,850 A
6, 1984 Inoue et al.

6,051,907. A
6,060,818 A

4/2000 Ylilammi
5/2000 Ruby et al.

4,608,541 A
4,625,138 A

8, 1986 Moriwaki et al.
11, 1986 Ballato

6,087,198 A
6,090,687 A

7/2000 Panasik
7/2000 Merchant et al.

4,633.285 A
4,640,756 A
4,719,383 A
4,769,272 A

12/1986 Hunsinger et al.
2/1987 Wang et al.

6,099,700 A
6,107,721 A
6,111,341 A
6,111,480 A

8/2000 Lee et al. ................. 204,192.18
8/2000 Lakin8, 2000 Hirama
8/2000 lyama et al.

4,529,904 A

7/1985 Hattersley

1/1988 Wang et al.

9/1988 Byrne et al.

6,114,795. A

5/2000 Tajima et al.

4,798,990 A

1, 1989 Henoch

6,118,181 A

9, 2000 Merchant et al.

4,819,215 A

4, 1989 Yokoyama et al.

6,124,678 A

9/2000 Bishop et al.

4,841,429 A
4,906,840 A
4,916,520 A
4,933,743 A

6, 1989 McClanahan et al.
3, 1990 Zdeblicket al.
4, 1990 Kurashima
6, 1990 Thomas et al.

6,131,256 A
6,150,703 A
6,187,513 B1
6, 198,208 B1

10/2000 Dydyk
1 1/2000 Cushman et al.
2/2001 Katakura
3/2001 Yano et al.

5,006,478 A
5,048,036 A

4, 1991 Kobayashi et al.
9, 1991 Scifres et al.

6,215,375 B1
6.219,032 B1

4/2001 Larson et al.
4/2001 Rosenberg et al.

5,048,038 A

9, 1991 Brennan et al.

6,219,263 B1

4/2001 Wulidart

5,066.925 A

1 1/1991 Freitag

6.228,675 B1

5/2001 Ruby et al.

5,067,959 A
5,111,157 A

2f1992 Omori et al.
5, 1992 Komiak

6.252,229 B1
6,262,600 B1

6/2001 Hays et al.
7/2001 Haigh et al.

5,118,982 A

6, 1992 Inoue et al.

6,263,735 B1

7/2001 Nakatani et al.

5,129,132 A

7, 1992 Zdeblicket al.

6,265.246 B1

7/2001 Ruby et al.

5,162,691 A

1 1/1992 Mariani et al.

6,278,342 B1

8/2001 Ella

5,241,209 A
5,241,456 A
5,262,347 A

8, 1993 Marcinkiewicz et al.
11/1993 Sands

5,270,492 A
5,294,898 A
5,361,077 A
5,382,930 A

5.448,014 A

4,836,882 A

5,075,641 A

5,166,646 A
5,185.589 A
5,214,392 A
5,233,259 A

5.3848O8 A

6, 1989 Ballato

12/1991 Weber et al.

1 1/1992 Avanic et al.
2/1993 Krishnaswamy et al.
5/1993 Kobayashi et al.
8/1993 Krishnaswamy et al.
8, 1993 Sasaki

6,124,756 A

6,229,247 B1

9, 2000 Yaklin et al.

5/2001 Bishop

6,284,121 B1
6.292,336 B1
6,306.755 B1
6,307.447 B1

9/2001 Reid
9/2001 Horng et al.
10/2001 Zheng
10/2001 Barber et al.
10/2001 Nakagawa

6,355.498 B1

1/2002 Roberts et al.
3/2002 Chan et al.

12/1993 Fukui
3/1994 Dworsky et al.
1 1/1994 Weber
1/1995 Stokes et al.

6,366,006 B1
6,376,280 B1
6,377,137 B1
6,384,697 B1

4/2002 Boyd
4/2002 Ruby et al.
4/2002 Ruby
5/2002 Ruby

9/1995 Kong et al.

6,407,649 B1

1/1995 Van Brunt et al.

6,307,761 B1
6,335,548 B1

6,396.200 B2

5, 2002 Misu et al.

6/2002 Tikka et al.

5,465,725 A
5,475,351 A
5,548,189 A
5,567,334. A

1 1/1995 Seyed-Boloforosh12/1995 Uematsu et al.
8, 1996 Williams
10/1996 Baker et al.

6,414,569 B1
6,420,820 B1,
6.424,237 B1
6,429,511 B2

7/2002 Nakafuku
7/2002 Larson
7/2002 Ruby et al.
8/2002 Ruby et al.

5,587,620 A

12/1996 Ruby et al.

6,437,482 B1

8/2002 Shibata

5,603,324 A

2/1997 Oppelt et al.

6,462,631 B2

10/2002 Bradley et al.

5,616,208 A

4, 1997 Lee .......................... 156,345.24

6,466,105 B1

10/2002 Loblet al.

5,633,574 A
5,671,242 A
5,692.279 A
5,698,928 A
5,704,037 A

5/1997 Sage
9/1997 Takiguchi et al.
12/1997 Mang et al.
12/1997 Mang et al.
12/1997 Chen

6,466,418 B1
6,469,597 B2
6,469,909 B2
6,472,954 B1
6,476,536 B1

10/2002 Horng et al.
10/2002 Ruby et al.
10/2002 Simmons
10/2002 Ruby et al.
1 1/2002 Pensala

5,705,877 A
5,729,008 A
5,789,845. A

1/1998 Shimada
3, 1998 Blalocket al.
8, 1998 Wadaka et al.

6.479,320 B1
6,483.229 B2
6,486,751 B1

1 1/2002 Gooch
11/2002 Larson et al.
1 1/2002 Barber et al.

5,714,917 A

5,589,858 A
5,594,705 A

10, 1996 Ella

12/1996 Kadowaki et al.
1/1997 Connor et al.

6,434,030 B1

6,441,539 B1
6,441,702 B1

8, 2002 Rehmet al.
8/2002 Kitamura et al.
8, 2002 Ella et al.

5,817.446 A

10/1998 Lammert

6,489,688 B1

12/2002 Baumann et al.

5,825,092 A

10/1998 Delgado et al.

6.492.883 B2

12/2002 Liang et al.

5,835,142 A

1 1/1998 Nakamura et al.

6,496,085 B2

12/2002 Ella et al.

US 9.243,316 B2Page 3(56)

References Cited
U.S. PATENT DOCUMENTS

6,498,604
6,507,983
6,515,558
6,518.860
6,525,996
6,528,344
6,530,515
6,534,900
6,542,055
6,548,942
6,548,943
6,549,394
6,550,664
6,559.487
6,559,530
6,564,448
6,566,956
6,566,979
6,580,159
6,583,374
6,583,688
6,593,870
6,594,165
6,600,390
6,601.276
6,603, 182
6,607.934
6,617,249
6,617,750
6,617,751
6,621,137
6,630,753
6,635,509
6,639,872
6,651488
6,657,363
6,668,618
6,670,866
6,677,929
6,693,500
6,710,508
6,710,681
6,713,314
6,714,102
6,720,844
6,720,846
6,724.266
6,738,267
6,750,593
6,774,746
6,777,263
6,787,048
6,788, 170
6,803,835
6,812,619
6,820,469
6,828,713
6,842,088
6,842,089
6,849,475
6,853,534
6,861,920
6,872,931
6,873,065
6,873.529
6,874,211
6,874,212
6,888,424
6,900,705
6,903,452
6,906,451
6,911,708
6,917.261
6,924,583
6,924,717 B2

12, 2002 Jensen
1, 2003 Ruby et al.
2, 2003 Ylilammi
2, 2003 Ella et al.
2, 2003 Miyazawa
3, 2003 Kang
3, 2003 Glenn et al.
3, 2003 Aigner et al.
4, 2003 Frank et al.
4, 2003 Panasik
4, 2003 Kaitila et al.
4, 2003 Williams
4, 2003 Bradley et al.
5/2003 Kang et al.
5/2003 Hinzel et al.
5/2003 Oura et al.
5/2003 Ohnishi et al.
5/2003 Larson et al.
6, 2003 Fusaro et al.
6, 2003 Knieser et al.
6, 2003 Klee et al.
T/2003 Dummermuth et al.
T/2003 Duerbaum et al.
T/2003 Frank8, 2003 Barber
8, 2003 Low et al.
8, 2003 Chang et al.
9, 2003 Ruby et al.
9, 2003 Dummermuth et al.
9, 2003 Sunwoo et al.
9, 2003 Ma et al.
10, 2003 Malik et al.
10, 2003 Ouellet
10, 2003 Rein11, 2003 Larson et al.
12, 2003 Aigner
12, 2003 Larson et al.
12, 2003 Ella et al.
1, 2004 Gordon et al.
2, 2004 Yang et al.
3, 2004 Ruby et al.
3, 2004 Figueredo et al.
3, 2004 Wong et al.
3, 2004 Ruby et al.
4, 2004 Lakin4, 2004 Iwashita et al.
4, 2004 Piazza et al.
5, 2004 Navas Sabater et al.
6, 2004 Iwata
8, 2004 Whatmore et al.
8, 2004 Gan et al.
9, 2004 Bradley et al.
9, 2004 Kaitila et al.
10, 2004 Frank
11, 2004 Kaitila et al.
11, 2004 Adkins et al.
12, 2004 Bradley et al.
1/2005 Yamada et al.
1/2005 Lee
2, 2005 Kim
2, 2005 Williams
3, 2005 Ishikawa et al.
3, 2005 Liess et al.
3, 2005 Haigh et al.
3, 2005 Ikuta
4, 2005 Bradley et al.
4, 2005 Larson
5/2005 Takeuchi et al.
5/2005 Nakamura et al.
6, 2005 Ma et al.
6, 2005 Yamada et al.
6, 2005 Park
7/2005 Unterberger
8, 2005 Lin et al.
8, 2005 Ginsburg et al.

6,927,651 B2
6,936,837 B2
6,936,928 B2
6,936,954 B2
6,941,036 B2
6,943,647 B2
6,943,648 B2
6,946,928 B2
6,954,121 B2
6,963,257 B2
6,970,365 B2
6,975, 183 B2
6,977.563 B2
6,985,051 B2
6,985,052 B2
6,987,433 B2
6,989,723 B2
6,998.940 B2
7,002.437 B2
7,019,604 B2
7,019,605 B2
7,026,876 B1
7,053.456 B2
7.057,476 B2
7,057.478 B2
7,064,606 B2
7,084,553 B2
7,091649 B2
7,098,758 B2
7,102.460 B2
7,109,826 B2
7,128,941 B2
7,129,806 B2
7,138,889 B2
7,161,448 B2
7,170,215 B2
7,173,504 B2
7,187,254 B2
7,199,683 B2
7,209,374 B2
7.212,083 B2
7.212,085 B2
7,230,509 B2
7,230,511 B2
7,233,218 B2
6,262,637 B1
7,242,270 B2
7,259,498 B2
7,268,647 B2
7,275,292 B2
7,276,994 B2
7,280,007 B2
7,281,304 B2
7,294.919 B2
7,301,258 B2
7,310,861 B2
7,313,255 B2
7,332,985 B2
7,345,410 B2
7,358,831 B2
7,367,095 B2
7,368,857 B2
7,369,013 B2
7,377,168 B2
7,385.467 B2
7.388,318 B2
7.388,454 B2
7,388,455 B2
7,391,286 B2
7,400,217 B2
7,408,428 B2
7,414,349 B2
7,414,495 B2
7,420,320 B2
7,423,503 B2
7,425,787 B2
7,439,824 B2
7.463,118 B2
7,466,213 B2

8, 2005 Larson, III et al.
8, 2005 Yamada et al.
8, 2005 Hedler et al.
8, 2005 Peczalski
9, 2005 Lucero
9, 2005 Aigner et al.
9, 2005 Maiz et al.
9, 2005 Larson et al.
10, 2005 Bradley et al.
11/2005 Ella et al.
11/2005 Turchi
12, 2005 Aigner et al.
12, 2005 Komuro et al.
1, 2006 Nguyen et al.
1, 2006 Tikka
1, 2006 Larson, III et al.
1, 2006 Komuro et al.
2, 2006 Metzger
2, 2006 Takeuchi et al.
3, 2006 Gotoh et al.
3, 2006 Larson
4, 2006 Esfandiari et al.
5/2006 Matsuo
6, 2006 Hwu
6, 2006 Korden et al.
6, 2006 Louis8, 2006 Ludwiczak
8, 2006 Larson, III et al.
8, 2006 Wang et al.
9, 2006 Schmidhammer et al.
9, 2006 Ginsburg et al.
10, 2006 Lee
10, 2006 Sato11, 2006 Lakin
1/2007 Feng et al.
1/2007 Namba et al.
2, 2007 Larson et al.
3, 2007 Su et al.
4, 2007 Liu
4, 2007 Noro
5/2007 Inoue et al.
5/2007 Wu
6, 2007 Stoemmer
6, 2007 Onishi et al.
6, 2007 Park et al.
7/2007 Bradley et al.
7/2007 Larson et al.
8, 2007 Nakatsuka et al.
9, 2007 Sano et al.
10, 2007 Ruby et al.
10, 2007 Takeuchi et al.
10, 2007 Feng et al.
10, 2007 Kim et al.
11/2007 Bai
11/2007 Tanaka
12, 2007 Aigner et al.
12, 2007 Machida et al.
2, 2008 Larson et al.
3, 2008 Grannen et al.
4/2008 Larson et al.
5/2008 Larson et al.
5/2008 Tanaka
5/2008 Fazzio et al.
5/2008 Liu
6, 2008 Stoemmer et al.
6, 2008 Yamada et al.
6, 2008 Ruby et al.
6, 2008 Larson
6, 2008 Jamneala et al.
T/2008 Larson et al.
8, 2008 Larson
8, 2008 Sasaki
8, 2008 Iwasaki et al.
9, 2008 Sano et al.
9, 2008 Larson et al.
9, 2008 Larson
10, 2008 Aigner
12, 2008 Jacobsen
12, 2008 Loblet al.

US 9.243,316 B2Page 4(56)

References Cited

U.S. PATENT DOCUMENTS

2006/0081048 A1

4/2006 Mikado et al.

2006/0O87199 A1

4/2006 Larson et al.

2006/0103492 A1
2006/01 19453 A1

5/2006 Feng et al.
6/2006 Fattinger et al.
6/2006 Wei et al.

7,482,737 B2

1/2009 Yamada et al.

2006, O121686 A1

7,508,286 B2

3/2009 Ruby et al.

2006.0125489 A1

6/2006 Feucht et al.

7,515,018 B2

4/2009 Handtmann et al.

2006, O132262 A1

6/2006 FaZZio et al.

7,535,324 B2

5/2009 Fattinger et al.

2006.0160353 A1

7/2006 Gueneau de Mussy et al.

7,545,532 B2
7,561,009 B2
7,576.471 B1

6, 2009 Muramoto
7/2009 Larson et al.
8, 2009 Solai

2006, O1641.83 A1
2006, O164186 A1
2006, O1974 11 A1

7/2006 Tikka et al.
7/2006 Stoemmer et al.
9, 2006 Hoen et al.

7,602,101 B2
7,619,493 B2

10/2009 Hara et al.
11/2009 Uno et al.

2006/0238070 A1
2006/0284.707 A1

10, 2006 Costa et al.
12/2006 Larson et al.

7,629,865 B2

12/2009 Ruby

1/2010 Akiyama et al.

2007.0035364 A1

2006/0290446 Al

12/2006 Aigner et al.

7,655,963 B2

2/2010 Sadaka et al.

2007/0O373.11 A1

2/2007 Izumi et al.

7.684, 109 B2
7,714,684 B2

3/2010 Godshalk et al.
5/2010 Ruby et al.

2007/00852.13 A1
2007/0O85632 A1

4, 2007 Anh et al.
4/2007 Larson et al.

7,768.364 B2
7,791434 B2
7,795,781 B2

8, 2010 Hart et al.
9, 2010 Fazzio et al.
9, 2010 Barber et al.

2007, OO86080 A1
2007/0O86274 A1
2007/00908.92 A1

4/2007 Larson et al.
4/2007 Nishimura et al.
4/2007 Larson

7,889,024 B2

2/2011 Bradley et al.

2007/0170815 A1

7, 2007 Unkrich8, 188,810 B2

5, 2012 Fazzio et al.

2007/01710O2 A1

7, 2007 Unkrich

8,248,185 B2
8,283,999 B2
8,507.919 B2

8/2012 Choy et al.
10/2012 Elbrecht et al.
8, 2013 Ishikura

2007/017671.0 A1
2007/0205850 A1
2007/0279153 A1

8/2007 Jamneala et al.
9/2007 Jamneala et al.

12/2007 Ruby

8,575,820 B2
8,673,121 B2

11/2013 Shirakawa et al.
3/2014 Larson et al.

2008.OO55020 A1
2008/0297.278 A1

3/2008 Handtmann et al.
12/2008 Handtmann et al.

8,872,604 B2
8,930.301 B2

10/2014 Burak et al.
1/2015 Traupman et al.

2008/0297.279 A1
2008/0297.280 A1

12/2008 Thalhammer et al.
12/2008 Thalhammer et al.

9,136,818 B2
9,136,819 B2
9,154,112 B2

9, 2015 Burak et al.
9/2015 Grannen et al.
10/2015 Burak2009 OO64498 A1
2009, OO793O2 A1
2009, OO96550 A1

3/2009 Mok et al.
3, 2009 Wall et al.
4/2009 Handtmann et al.

2001/0026951
A1
2002fOOOO646 A1

10/2001
Vergani et al.
1/2002 Gooch et al.

2002fOO63497 A1

5, 2002 Panasik

2009, O153268 A1
2010, 0013573 A1

6/2009 Milson et al.
1/2010 Umeda

20020070463 A1
2002/O1265.17 A1

6/2002 Chang et al.
9, 2002 Matsukawa et al.

20100052176 A1
2010/0052815 A1

3/2010 Kamada et al.
3/2010 Bradley et al.

2002fO140520 A1

10, 2002 Hikita et al.

2010/0091,370 Al

4, 2010 Mahrt et al.

7,642,693 B2

2002fO190814 A1* 12/2002 Yamada et al. ............... 333,187
2003/0001251 A1
1/2003 Cheever et al.

2009/0127978 Al

2010.0102358 A1
2010, O148637 A1

2/2007 Sridhar et al.

5/2009 Asai et al.

4/2010 Lanzien et al.
7, 2010 Satou

2003, OOO6502 A1

1/2003 Karpman

2010/0176899 A1

7/2010 Schaufele et al.

2003, OO11285 A1

1/2003 OSSman

2010, 0180391 A1

7/2010 Larson et al.

2003, OO11446 A1
2003/0051550 A1

1/2003 Bradley
3/2003 Nguyen et al.

2010.0187948 A1
2010.0187949 A1

7/2010 Sinha et al.
7/2010 Sinha et al.

2003, OO87469 A1

5, 2003 Ma

2010.0260453 A1

10, 2010 Block2003.0102776 A1

6, 2003 Takeda et al.

2010/0327994 A1

12/2010 Choy et al.

2003/011 1439 A1

6/2003 Fetter et al.

2012fO218056 A1

2/2011 Burak

2003. O132493 A1

7/2003 Kang et al.

2012fO218055 A1

3, 2011 Burak et al.
4/2011 Bonilla et al.

2003/0132809 A1

7/2003 Senthilkumar et al.

2011/0092067 A1

2003. O141946 A1

7/2003 Ruby et al.

2011 0121689 A1

5/2011 Grannen et al.

2003/O155574 A1

8, 2003 Doolittle

2011 0180391 A1

7/2011 Larson et al.

2003/0179053 A1
2004, OO16995 A1
2004.0017130 A1

9/2003 Aigner et al.
1/2004 Kuo et al.
1/2004 Wang et al.

2011/0204997 A1
2011/0266917 A1
2012/017781.6 A1

8, 2011 Elbrecht et al.
1 1/2011 Metzger et al.
7/2012 Larson et al.

2004.0056735 A1

3/2004 Nomura et al.

2012fO248941 A1

10, 2012 Shirakawa et al.

2004/0092234 A1

5/2004 Pohjonen

2012/0326807 A1

12/2012 Choy et al.

2004.0099898 A1
2004/0129079 A1
2004/O150296 A1

5, 2004 Grivna et al.
7/2004 Kato et al.
8, 2004 Park et al.

2013,0003377 A1
2013/0106534 A1
2013/O127300 A1

1/2013 Sakai et al.
5, 2013 Burak et al.
5, 2013 Umeda et al.

2004O166603 A1

8/2004 Carley2013,0221454 A1

8, 2013 Dunbar et al.

2004/0195937 A1

10/2004 Shogo Matsubara et al.

2013/0334625 A1

12/2013 Lin

2004/02571.71 A1

12, 2004 Park et al.

2014/01 18089 A1

5/2014 Bradley et al.

2005, OO12716 A1
2005/0023931 A1
2005.0036604 A1

1/2005 Mikulin et al.
2/2005 Bouche et al.
2/2005 Scott et al.

2014/O1321.17 A1
2015,0311046 A1

5/2014 Larson et al.
10, 2015 Yeh et al.

2005, OO82626 A1

4/2005 Leedy

2005/OO93657 A1

5, 2005 Larson et al.

E.

o3.

3.

2005.0167795 A1
2005/0206271 A1
2005/0206479 A1
2005/0206483 A1
2005/0248232 A1

8/2005 Higashi
9/2005 Higuchi et al.
9/2005 Nguyen et al.
9/2005 Pashby et al.
1 1/2005 Itaya et al.

EP
EP
EP
EP
EP

O865.157
88O22710471.89
1096,259

1100 196

9, 1998
11, 1998
10, 2000
5, 2001
5, 2001

2005/0269904 A1
2006, OO17352 A1

12, 2005 Oka
1/2006 TanielianEPEP

1180494
1249932

2, 200210, 2002

2006, OO71736 A1

4/2006 Ruby et al.

EP1258989

11, 2002

2005/0093396 A1
2005/OO93655 A1

FOREIGN PATENT DOCUMENTS

5, 2005 Larson et al.
5, 2005 Larson et al.

US 9.243,316 B2Page 5
(56)

EP
EP
EP
EP
EP
EP
EP
EP
EP
EP
EP
EP
GB
GB
GB
GB
GB
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
JP
KR
KR
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO

References Cited

Martin, et al. “Shear Mode Coupling and Tilted Gram Growth of AIN

FOREIGN PATENT DOCUMENTS

Ferroelectrics, and Frequency Control, Jul. 2006, p. 1339-1343, vol.

12589901517443
1517444
1528674
1528675
1528676
1528677
1542362
15579451575165
O973256
2299593
12O7974
2013343241.1239
241.8791
24.27773
359023612
61054686
62109419
62200813
129551221090706005.944
8330878
O9027729
983O29103245610173479
2000031552
200O232334
2000295.065
2000332568
2001102901
2OO1508630
2002217676
2003O17964
2003O17974
2003505905
2003505906
2000076295
2003124779
2003332872
2006 109472
2006295924
2006.319796
2007 OO65O1
2007028669
2007295.306
2003OO48917
100806504
WO9816957
WO9838736
WO9856O49
WO9937023
WOO 106646
WOO 106647
WOO 199276
WOO2103900
WOO3O3O358
WOO3O43.188
WOO305.0950
WOO3058.809
WO2004O34579
WO2004051744
WO2004102688
WO2005043752
WO2005043753
WO2005043756
WO2006O18788

11, 2002
3, 2005
3, 2005
5, 2005
5, 2005
5, 2005
5, 2005
6, 2005
7/2005
9, 2005
9, 2006
3, 2011
10, 1970
8, 1979
8, 2005
4/2006
1, 20072, 1984
3, 1986
5, 1987
9, 1987
11, 1989
1, 1990
1, 1994
12/1996
1, 1997
3, 1997
2, 1998
6, 1998
1, 2000
8, 2000
10, 2000
11, 2000
4/2001
6, 2001
8, 2002
1, 20031, 20032, 20032, 20033, 20034/200311, 2003
4/200610, 2006
11, 2006
1, 20072, 200711, 2007
6, 20032, 2008
4f19989, 1998
12/1998
7, 1999
1, 2001
1, 2001
12/2001
12/2002
4/2003
5, 20036, 2003
T 20034/2004
6, 2004
11, 2004
5, 2005
5, 2005
5, 2005
2, 2006

OTHER PUBLICATIONSMartin, et al. "Re-growth of c-axis oriented AIN thin films'. IEEE
Ultrasonics Symposium, 2006, p. 169-172.

Thin Films in BAW Resonators', IEEE Transactions on Ultrasonics,
53, No. 7.

Co-pending Application No. 13/161.946, filed Jun. 16, 2011.
Machine Translation of JP2003505905 published Feb. 12, 2003.
Machine Translation of JP2003505906 published Feb. 12, 2003.
Machine Translation of WO2004034579 published Apr. 22, 2004.
Machine Translation of WO2004102688 published Nov. 25, 2004.
Machine Translation of JP2006 109472 published Apr. 20, 2006.
Machine Translation of JP2006295924 published Oct. 26, 2006.
Machine Translation of JP2007028669 published Feb. 1, 2007.
Machine Translation of JP2007006501 published Jan. 11, 2007.
Machine Translation of JP2006319796 published Nov. 11, 2006.
Machine Translation of JP2007295306 published Nov. 8, 2007.
Machine Translation of WO9838736 published Sep. 3, 1998.
Machine Translation of JP983029 published Mar. 28, 1997.
Machine Translation of JP8330878 published Dec. 13, 1996.
Apartial copy of GB search report for Application No. GB0525884.3
Feb. 2, 2006, 4 pages.
British search report Application No. GB0605222.9 Jul. 11, 2006.
Examination report corresponding to application No. GB0605770.7
Aug. 25, 2006.
Examination report from UK for application GB0605971. 1 Aug. 24.
2006.

Search report for Great Britain patent application No. 06.17742.2
Dec. 13, 2006.

Search report for Great Britain Patent Application No. 06.17742.2
Mar. 29, 2007.

Search report from corresponding application No. GB0605225.2
Jun. 26, 2006.

Search report from Corresponding Application No. GB0620152.9
Nov. 15, 2006.

Search report from Corresponding Application No. GB0620653.6
Nov. 17, 2006.

Search report from Corresponding Application No. GB0620655.1
Nov. 17, 2006.

Search report from Corresponding Application No. GB0620657.7
Nov. 23, 2006.

Examination report from Corresponding Application No.
GB0605779.8 Aug. 23, 2006.
Search report in the Great Britain Patent Application No.

GB0619698.4 Nov.30, 2006.

Akiyama, et al., “Enhancement of Piezoelectric Response in
Scandium Aluminum Nitride Alloy Thin Films Prepared by Dual
Reactive Cosputtering”. Advanced Materials, vol. 21, 2009, pp. 593
596.

Al-Ahmad, et al., “Piezoelectric-Based Tunable Microstrip Shunt
Resonator'. Proceedings of Asia-Pacific Microwave Conference,
2006.

Aoyama, et al., “Diffusion of Boron, Phosphorus, Arsenic and Antimony in Thermally Grown SiliconDioxide'. Journal of Electrochemical Society, vol. 146 (5), pp. 1879-1883, 1999.
Auld, "Acoustic Resonators'. Acoustic Fields and Waves in Solids,

Second Edition, vol. 2, 1990, pp. 250-259.
Bauer, et al., “Properties of Silicon Implanted with Boron Ions
through Thermal Silicon Dioxide'. Solid State Electronics, vol. 16,
No. 3, 1973, pp. 289-300.
Bi, et al., “Bulk Acoustic Wave RF Technology”, IEEE Microwave
Magazine, vol. 9, Issue 5, 2008, pp. 65-80.
Choi, et al., “Design of Half-Bridge Piezo-Transformer Converters in
the AC Adapter Applications”, APEC 2005, IEEE, Mar. 2005, pp.
244-248.

Coombs, "Electronic Instrument Handbook'. Second Edition,

McGraw-Hill Inc., 1995, pp. 5.1-5.29.
C-S Lee, et al., “Copper-Airbridged Low-Noise GaAs PHEMT with
Ti/Winx Ti Diffusion Barrier for High-Frequency Applications”
IEEE Transactions on Electron Devices, vol. 53, Issue 8, 2006, pp.
1753-1758.

Denisse, et al., “Plasma-Enhanced Growth and Composition of Sili
con Oxynitride Films”. Journal of Applied Physics, vol. 60, No. 7.
Oct. 1, 1986, pp. 2536-2542.

US 9.243,316 B2Page 6(56)

References Cited
OTHER PUBLICATIONSFattinger, et al., “Coupled Bulk Acoustic Wave Resonator Filters:
Key technology for single-to-balanced RF filters', IEEE MTT-S
Digest, 2004, pp. 927-929.
Fattinger, et al., “Single-to-balance Filters for Mobile Phones Using
Coupled Resonator BAWTechnology', 2004 IEEE Ultrasonics Sym
posium, Aug. 2004, pp. 416-419.
Fattinger, et al., “Spurious Mode Suppression in Coupled Resonator
Filters', IEEE MTT-S International Microwave Symposium Digest,
2005, pp. 409–412.
Gilbert, "An Ultra-Miniature, Low Cost Single Ended to Differential
Filter for ISM Band Applications'. Microwave Symposium Digest,
2008 IEEE MTT-S, Jun. 2008, pp. 839-842.
Grill, et al., “Ultralow-K Dielectrics Prepared by Plasma-Enhanced
Chemical Vapor Deposition'. Applied Physics Letters, vol. 79, 2001,
pp. 803-805.
Hadimioglu et al., “Polymer Films as Acoustic Matching Layers'.
1990 IEEE Ultrasonics Symposium Proceedings, vol. 3, Dec. 1990,
pp. 1337-1340.
Hara, "Surface Treatment of Quartz Oscillator Plate by Ion Implan
tation”, Oyo Buturi, vol. 47, No. 2, Feb. 1978, pp. 145-146.
Holzlohner et al., "Accurate Calculation of Eye Diagrams and Bit
Error Rates in Optical Transmission Systems. Using Linearization'.
Journal of Lightwave Technology, vol. 20, No. 3, Mar. 2002, pp.
389-400.

lvensky, et al., “A Comparison of Piezoelectric Transformer AC/DC
Converters with Current Doubler and voltage Doubler Rectifiers'.
IEEE Transactions on Power Electronics, vol. 19, No. 6, Nov. 2004.

Jamneala, et al., “Coupled Resonator Filter with Single-Layer Acous
tic Coupler'. IEEE Transaction on Ultrasonics, Ferroelectrics, andFrequency Control, vol. 55, Oct. 2008, pp. 2320-2326.
Jamneala, et al., “Ultra-Miniature Coupled Resonator Filter with
Single-Layer Acoustic Coupler'. IEEE Transactions on Ultrasonics,
Ferroelectrics, and Frequency Control, vol. 56, No. 11, Nov. 2009,
pp. 2553-2558.
Jiang, et al., “A Novel Single-Phase Power Factor Correction
Scheme", IEEE, 1993, pp. 297-292.
Jung, et al., “Experimental and Theoretical Investigation on the Rela
tionship Between AIN Properties and AIN-Based FBAR Character
istics', 2003 IEEE International Frequency Control Symposium and
PDA Exhibition Jointly with the 17th European Frequency and Time
Forum Sep. 3, 2003, pp. 779-784.
Kaitila, et al., “Measurement of Acoustical Parameters of Thin

Films', 2006 IEEE Ultrasonics Symposium, Oct. 2006, pp. 464-467.
Spangenberget al., “Dependence of the Layer of Resistance of Boron
Implantation in Silicon and the Annealing Conditions'. Comptus
Rendus de l'Academic Bulgares des Sciences, vol. 33, No. 3, 1980,
pp. 325-327.
Tas, et al., “Reducing Anchor Loss in Micromechanical Extensional
Mode Resonators', IEEE Transactions on Ultrasonics, Ferroelectrics

and Frequency Control, vol. 57, No. 2, Feb. 2010, pp. 448-454.
Thomsen, et al., "Surface Generation and Detection of Phonons by
Picosecond Light Pulses”. Physical Review B. vol.34, No. 6, Sep. 15
1986, pp. 4129-4138.
Tiersten, et al., “An Analysis of Thickness-Extensional Trapped
Energy Resonant Device Structures with Rectangular Electrodes in
the Piezoelectric Thin Film on Silicon Configuration”, Journal ofApplied Physics, 54 (10), Oct. 1983, pp. 5893-5910.
Topich, et al., “Effects of Ion Implanted Fluorine in Silicon Dioxide'.
Nuclear Instr. And Methods, Cecon Rec, Cleveland OH, May 1978,
pp. 70-73.
Tsubbouchi, et al., “Zero Temperature coefficient Surface Acoustic
Wave Devices using Epitaxial AIN Films'. IEEE Ultrasonics Sym
posium, San Diego CA, 1982, pp. 240-245.
Vasic, et al., “A New Method to Design Piezoelectric Transformer
Used in MOSFET & IGBT Drive Circuits’, IEEE 34th Annual PowerElectronics Specialists Conference, 2003, vol. 1, Jun. 15-19, 2003,
pp. 307-312.

Vasic, et al., “A New MOSFET & IGBT Gate Drive Insulated by aPiezoelectric Transformer', IEEE 32nd Annual Power Electronics

Specialists Conference, vol. 3, 2001, pp. 1479-1484.
Yanagitani, et al., “Giant Shear Mode Electromechanical Coupling
Coefficient k15 in C-Axis Tilted ScAIN Films', IEEE International

Ultrasonics Symposium, Oct. 2010, pp. 2095-2098.
Yang, et al., “Highly C Axis Oriented AIN Film Using Mocvd for
5GHx Band FBAR Filter', 2003 IEEE Ultrasonics Symposium, Oct.
5, 2003, pp. 170-173.
Pensala, et al., “Spurious resonance Suppression in gigahertz-range
ZnO thin-film bulk acoustic wave resonators by the boundary frame
method:modeling and experiment”. IEEE Transactions on Ultrason
ics, Ferroelectrics, and Frequency Control, vol. 56, No. 8, Aug. 2009,
pp. 1731-1744.
Lynch, “Precise Measurements on Dielectric and Magnetic Materi
als', IEEE Transactions on Instrumentation and Measurement, vol.
IM-23, No. 4, Dec. 1974, pp. 425-431.
Ranjan, et al., “Strained Hexagonal ScN: A Material with Unusual
Structural and Optical Properties'. Physical Review Letters, vol.90,
No. 25, Jun. 27, 2003.

Farrer, et al., “Properties of Hexagonal ScN versus wurtzite GaN and
InN’. Physical Review B 66, Nov. 20, 2002.
Constantin, et al., “Composition-dependent structural properties in
ScGaN alloy films: a combined experimental and theoretical study”.
Journal of Applied Physics, vol. 98, Dec. 16, 2005.
Suzuki, et al., “Influence of shadowing effect on shear mode acoustic
properties in the c-axis tilted AI films'. IEEE Ultrasonics Sympo
sium, Oct. 2010, pp. 1478-1481.
Krishnaswamy, et al., “Film Bulk Acoustic Wave Resonator Tech
nology”, 1990 Ultrasonics Symposium, May 29, 1990, pp. 529-536.
Machine translation of JP2003332872 published Nov. 21, 2003.
Apartial copy ofGB search report for Application No. GB0522393.8
Jan. 9, 2006, 4 pages.
Lakin, “Bulk Acoustic Wave Coupled Resonator Filters', 2002 IEEE
International Frequency Control Symposium and PDA Exhibition,
May 2002, pp. 8-14.
Machine translation of KR20030048917 published Jun. 25, 2003.
Machine translation of WO9937023 published Jul 22, 1999.
Machine translation of CN101 170303 published Apr. 30, 2008.
Machine translation of WO03030358 published Apr. 10, 2003.
Machine translation of WO03043188 published May 22, 2003.
Machine translation of WO0305.0950 published Jun. 19, 2003.
Machine translation of DE 10239317 published Mar. 11, 2004.
Machine translation of JP2000232334 published Aug. 22, 2000.
Machine translation of JP2000295065 published Oct. 20, 2000.
Machine translation of JP2000031552 published Jan. 28, 2000.
Machine translation of JP2000332568 published Nov.30, 2000.
Machine translation of JP2001102901 published Apr. 13, 2001.
Machine translation of JP200 1508630 published Jun. 26, 2001.
Machine translation of JP2002217676 published Aug. 2, 2002.
Machine translation of JP2003017964 published Jan. 17, 2003.
Machine translation of JP2003124779 published Apr. 25, 2003.
Machine translation of JP2003017974 published Jan. 17, 2003.
Machine Translation of KR100806504 published Feb. 21, 2008.
Machine Translation of WO02103900 published Dec. 27, 2002.
Machine Translation of JP10173479 published Jun. 26, 1998.
Machine Translation of KR20020050729 published Jun. 27, 2002.
Machine Translation of JP2000076295 published Mar. 14, 2003.
Lakin, "Coupled Resonator Filters', 2002 IEEE Ultrasonics Sympo
sium, Mar. 2, 2002, pp. 901-908.
Lakin, et al., “High Performance Stacked Crystal Filters for GPS and
WideBandwidth Applications”, 2001 IEEE Ultrasonics Symposium,
Jan. 1, 2001, pp. 833-838.
Lakin, et al., “Temperature Compensated Bulk Acoustic Thin Film
Resonators', 2000 IEEE Ultrasonics Symposium San Juan Puerto
Rico, Oct. 2000, pp. 855-858.
Lakin, “Thin Film BAW Filters for Wide Bandwidth and High Per
formance Applications”, IEEE Microwave Symposium Digest, 2004
MTT-S International, vol. 2, Jun. 6-11 2004, pp. 923-926.
Lakin, “Thin Film Resonators and Filters', IEEE Ultrasonics Sym
posium, Caesar's Tahoe, NV, vol. 2, Oct. 1999, pp. 895-906.

US 9.243,316 B2Page 7(56)

References Cited
OTHER PUBLICATIONSLakin, et al., “WideBandwidth. Thin Film BAW Filters', 2004 IEEE

Ultrasonics, Ferroelectrics, and Frequency Control Joint 50th Anni
versary Conference, vol. 1, Aug. 2004, pp. 407-410.
Larson, et al., “Measurement of Effective Kt 2, O.Rp, Rs vs. Tempera
ture for Mo/AIN FBAR Resonators', IEEE Ultrasonics Symposium,
2002, pp. 939-943.
Lee, et al., “Optimization of Frame-Like Film Bulk Acoustic Resonators for Suppression of Spurious Lateral Modes Using Finite Element Method”. IEEE Ultrasonics Symposium, vol. 1, 2004, pp. 278
281.

Li, et al., “AC-DC Converter with Worldwide Range Input Voltage by
Series and Parallel Piezoelectric Transformer Connection', 35th

Annual IEEE Power Electronics Specialists Conference, 2004, pp.
2668-2671.

Lobl, et al., “Piezoelectric Materials for BAW Resonators and Fil

ters', 2001 IEEE Ultrasonics Symposium, Jan. 1, 2001, pp. 807-811.
Loboda, “New Solutions for Intermetal Dielectrics Using
Trimethylsilane-Based PECVD Processes'. Microelectronics Eng.,
vol. 50, 2000, pp. 15-23.
Martin, et al., “Development of a Low Dielectric Constant Polymer
for the Fabrication of Integrated Circuit Interconnect”. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol.
53, No. 7, Jul. 2006, pp. 1339-1343.
Martinez, et al., “High confinement Suspended micro-ring resonatorsin silicon-on-insulator'. Optics Express, vol. 14, No. 13, Jun. 26.
2006, pp. 6259-6263.
Navas, et al., “Miniaturised Battery Charger using PiezoelectricTransformers'. Applied Power Electronics Conference and Exposi
tion, 2001 Sixteenth Annual IEEE, vol. 1, pp. 492-496.
Ng, et al., “The Diffusion Ion-Implated Boron in Silicon Dioxide'.
AIP Conf. Proceedings, No. 122, 1984, pp. 20-33.
Ohta, et al., “Temperature Characteristics of Solidly Mounted Piezo
electric Thin Film Resonators', IEEE Ultrasonics Symposium,
Honolulu HI. Oct. 2003, pp. 2011-2015.

Pandey, et al., “Anchor Loss Reduction in Resonant MEMS using
MESA Structures'. Proceedings of the 2nd IEEE International Con
ference on Nano/Micro Engineered and Molecular Systems,
Bangkok Thailand, Jan. 16-19, 2007, pp. 880-885.
Pang, et al., “High Q Single-Mode High-Tone Bulk Acoustic Resonator Integrated with Surface-Machined FBAR Filter'. Microwave
Symposium Digest, IEEE MTT-S International, 2005, pp. 413-416.
Parker, et al., “Temperature-Compensated Surface Acoustic-Wave
Devices with SiO2 Film Overlays”, Journal of Applied Physics, vol.
50, Mar. 1979, pp. 1360-1369.
Pensala, “Thin film bulk acoustic wave devices: performance opti
mization and modeling'. http://www.vtt.fi.inf pdf publications/
2011/P756.pdf.
Reinhardt, et al., “Design of Coupled Resonator Filters Using Admit
tance and Scattering Matrices”, 2003 IEEE Ultrasonics Symposium,
May 3, 2003, pp. 1428-1431.
Ruby, “MicroMachined Thin Film Bulk Acoustic Resonators', IEEE
Internation Frequency Control Symposium, 1994, pp. 135-138.
Ruby, et al., “The Effect of Perimeter Geometry on FBARResonator
Electrical Performance'. Microwave Symposium Digest, 2005 IEEE
MTT-S International, Jun. 12, 2005, pp. 217-221.
Sanchez, et al., “Mixed Analytical and Numerical Design Method for
Piezoelectric Transformers', IEEE Xplore, 2003, pp. 841-846.
Schoenholz, et al., “Plasma-Enhanced Deposition of Silicon
Oxynitride Films”. Thin Solid Films, 1987, pp. 285-291.
Schuessler, “Ceramic Filters and Resonators'. Reprinted from IEEE
Trans Sonics Ultrason., vol. SU-21, Oct. 1974, pp. 257-268.
Shirakawa, et al., “Bulk Acoustic Wave Coupled Resonator Filters
Synthesis Methodology', 2005 European Microwave Conference,
vol. 1, Oct. 2005.

Small, et al., “A De-Coupled Stacked Bulk Acoustic Resonator(DSBAR) Filter with 2 dB Bandwidth >4%”, 2007 IEEE Ultrasonics
Symposium, Oct. 2007, pp. 604-607.

* cited by examiner

U.S. PatentJan. 26, 2016

Sheet 1 of 10

US 9.243,316 B2

X

100
111

XXX XXXXX XXXX XXXN-105

7

102

ZZ to
103

106

FIG. 1AU.S. PatentJan. 26, 2016

Sheet 2 of 10

US 9.243,316 B2

111
&

102

108

ZZZZZZZ

103

110
101

7

ZZ YaYNYSYNYSXYYQYNYSYNYSYNYSYNYSYNYSYNYS
Saša
Z Z Siasa
Z ZZ Z Sasa/,
Z Z Z Z Z

Z

SYS

4

7

/ A /

/

/

/

/

/

/

AZ
107

FIG. 1B

U.S. PatentJan. 26, 2016

Sheet 3 of 10

US 9.243,316 B2

111

102

103
106
101

2
FIG. 2A

U.S. PatentJan. 26, 2016

Sheet 4 of 10

US 9.243,316 B2

111

102

110
101

//ZSSYinNSN NSN<2ZZZZZZZZZZYaYNYSYNYSXYYQYNYSYNYSYNYSYNYSYNYSYNYS

7
Z

7

/ A /

/

/

/

/

/

/

YaYaNYSYNYSYNYSYNYSYNYSYNYNYSYNYSYNYSYN

ZAZ
FIG. 2B

U.S. PatentJan. 26, 2016

Sheet 5 of 10

US 9.243,316 B2Z2

ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ2

309

304
308

42

303
306

301

s

221
/

FIG. 3A

U.S. PatentJan. 26, 2016

Sheet 6 of 10

US 9.243,316 B2

309
305

304
303
306

301

2
3

FIG. 3B

U.S. PatentJan. 26, 2016

Sheet 7 of 10

401

OO
400

FIG. 4

US 9.243,316 B2

U.S. PatentJan. 26, 2016

Sheet 8 of 10

Forming a First ElectrodeOver a Substrate

Forming a Seed
Over the Substrate

Flowing a First Component ofPiezoelectric Material and

Sputtering a Layer of the
Piezoelectric Material Over the
Substrate

FIG. 5

US 9.243,316 B2

U.S. PatentJan. 26, 2016

Sheet 9 of 10

Providing a Substrate

Flowing Hydrogen Overthe Substrate

Flowing First Component
to Form a Piezoelectric Layer
Over a Target

Sputtering the PiezoelectricMaterial from the Target
to the Substrate

FIG. 6

US 9.243,316 B2

US 9.243,316 B2
1.
METHOD OF FABRICATINGPIEZOELECTRIC MATERAL WITH
SELECTED C-AXIS ORIENTATIONBACKGROUND

2
the FBAR to decrease. Similarly, a mechanical stress applied
to the FBAR that causes the thickness of the FBAR to change
in a first direction will generate a Voltage of the given polarity
between the electrodes of the FBAR, whereas a mechanicalstress that causes the thickness of the FBAR to change in asecond direction, opposite the first direction, will generate a
In many electronic applications, electrical resonators are voltage of the opposite polarity between the electrodes of theused. For example, in many wireless communications FBAR. As such, a mechanical stress applied to the FBAR thatdevices, radio frequency (RF) and microwave frequency reso causes the thickness of the FBAR to increase will generate anators are used as filters to improve reception and transmis 10 Voltage of the given polarity, whereas a mechanical stress thatsion of signals. Filters typically include inductors and capaci causes the thickness of the FBAR to decrease will generate a
Voltage of the opposite polarity.
tors, and more recently resonators.
As will be appreciated, it is desirable to reduce the size of
The piezoelectric layer of an FBAR is often grown over acomponents of electronic devices. Many known filter tech first electrode and beneath a second electrode. Theorientation
nologies present a barrier to overall system miniaturization. 15 of the C-axis can be governed by the first layer formed overWith the need to reduce component size, a class of resonators the first electrode. For example, in growing aluminum nitride
based on the piezoelectric effect has emerged. In piezoelec (AIN) with a C film orientation, the formation of a native
tric-based resonators, acoustic resonant modes are generated oxide layer over the first electrode (e.g., Mo) is believed toin the piezoelectric material. These acoustic waves are con cause the first layer of the piezoelectric crystal to be Al.
Verted into electrical waves for use in electrical applications. Ultimately, the crystalline orientation of the AIN formed
One type of piezoelectric resonator is a Bulk Acoustic results in piezoelectric films having C, orientation and its
Wave (BAW) resonator. The BAW resonator includes an attendant properties. Growth of Cypiezoelectric layers (e.g.,
acoustic stack comprising, interalia, a layer of piezoelectric AlN) by known methods has proven to be more difficult. It ismaterial disposed between two electrodes. Acoustic waves believed that nitrogen and oxygen may be adsorbed at theachieve resonance across the acoustic stack, with the resonant 25 surface of the first electrode, with the forming of a layer of Al
frequency of the waves being determined by the materials in over this adsorbed material. As such, rather than forming thethe acoustic stack. One type of BAW resonator comprises a desired Cy piezoelectric layer, C. piezoelectric material ispiezoelectric film for the piezoelectric material. These reso formed.
nators are often referred to as Film Bulk Acoustic Resonators
In certain applications, it is desirable to be able to select the
30 orientation of the piezoelectric material, and to fabricate both
(FBAR).
FBARs are similar in principle to bulk acoustic resonators C-piezoelectric material and C-piezoelectric material on thesuch as quartz, but are scaled down to resonate at GHz fre same structure. For example, in certain applications it is use
quencies. Because the FBARs have thicknesses on the order ful to provide a single-ended input to a differential output.
of microns and length and width dimensions of hundreds of One known resonator structure having a differential output
microns. FBARs beneficially provide a comparatively com 35 comprises coupled mode resonators. Filters based on coupledpact alternative to certain known resonators.
mode acoustic resonators are often referred to as coupled
FBARs may comprise a membrane (also referred to as the resonator filters (CRFs). CRFs have been investigated andacoustic stack) disposed over air. Often, such a structure implemented to provide improved passband and isolation ofcomprises the membrane Suspended over a cavity provided in the transmit band and receive band of duplexers, for example.
a substrate over which the membrane is suspended. Other 40 One topology for CRFs comprises an upper FBAR and a
FBARs may comprise the membrane formed over an acoustic lower FBAR. The two electrodes of one of the FBARS com
mirror formed in the substrate. Regardless of whether the prise the differential outputs, and one of the inputs to themembrane is formed over air or over an acoustic mirror, thelower resonator provides the single-ended input. The second
membrane comprises a piezoelectric layer disposed over a electrode provides the ground for the device. However, while
first electrode, and a second electrode disposed over the 45 the stacked-FBAR CRF shows promise from the perspective
piezoelectric layer.
of improved performance and reduced area or footprint due to
The piezoelectric layer comprises a crystalline structure its vertical nature, in order to attain this structure, the orien
and a polarization axis. Piezoelectric materials either com tation of the compression axes (C-axes) of individual piezopress or expand upon application of a Voltage. By convention, electric materials must be tailored to the application. Fora piezoelectric material that compresses when a Voltage of a 50 example, it may be useful to have one piezoelectric layer withcertain polarity is applied is referred to as compression-posi its C-axis (e.g., CA) in one direction, and the second piezo
tive (C) material, whereas a piezoelectric material that electric layer to have its crystalline orientation anti-parallel
expands upon application of the Voltage is referred to as a (e.g., C.) to the C-axis of the first piezoelectric layer. Unfor
compression-negative (C) material. The polarization axis of tunately, and as alluded to above, using known methods of
C. piezoelectric materials is antiparallel to the polarization 55 fabricating piezoelectric layers, it is difficult to select theaxis C material.
orientation of the piezoelectric crystal during fabrication, andAn FBAR is a polarity-dependent device as a result of especially on the same wafer.
polarity dependence of the piezoelectric material that consti
What is needed, therefore, is a method of fabricating piezo
tutes part of the FBAR. A voltage of a given polarity applied electric materials that overcomes at least the known short
between the electrodes of the FBAR will cause the thickness 60 comings described above.
of the FBAR to change in a first direction, whereas the same
SUMMARY
voltage of the opposite polarity will cause the thickness of the
FBAR to change in a second direction, opposite the firstIn accordance with a representative embodiment, a method
direction. (The thickness of the FBAR is the dimension of the
FBAR between the electrodes.) For example, a voltage of the 65 of fabricating a piezoelectric material comprising a first com
given polarity will cause the thickness of the FBAR to ponent and a second component comprises: providing a Sub
increase whereas a Voltage of the opposite polarity will cause strate; flowing hydrogen over the substrate; flowing the firstUS 9.243,316 B2
4
ordinary skill in the art. For example, approximately thesame means that one of ordinary skill in the art would con
sider the items being compared to be the same.

3
component to form the piezoelectric material over a target;and sputtering the piezoelectric material from the target on
the substrate.

In accordance with another representative embodiment, a
DETAILED DESCRIPTION
method of fabricating a bulk acoustic wave (BAW) resonator 5comprises: forming a first electrode over a Substrate; forming
In the following detailed description, for purposes ofa seed layer over the Substrate; depositing a piezoelectricmaterial having a compression-negative (C) polarity, the explanation and not limitation, specific details are set forth indepositing comprising: flowing a first component of the order to provide a thorough understanding of illustrative
piezoelectric material to form the piezoelectric material over 10 embodiments according to the present teachings. However, ita target comprising a second component of the piezoelectric will be apparent to one having ordinary skill in the art having
material; and Sputtering the piezoelectric material from the had the benefit of the present disclosure that other embodi
ments according to the present teachings that depart from thetarget to the Substrate.
specific details disclosed herein remain within the scope of
15 the appended claims. Moreover, descriptions of well-known
BRIEF DESCRIPTION OF THE DRAWINGS
apparati and methods may be omitted so as to not obscure the
The illustrative embodiments are best understood from thedescription of the illustrative embodiments. Such methods
following detailed description when read with the accompa and apparati are clearly within the scope of the present teachnying drawing figures. It is emphasized that the various fea ings.
Generally, it is understood that the drawings and the varitures are not necessarily drawn to Scale. In fact, the dimensions may be arbitrarily increased or decreased for clarity of ous elements depicted therein are not drawn to scale. Further,
discussion. Wherever applicable and practical, like reference relative terms, such as “above,” “below,” “top,” “bottom.”numerals refer to like elements.
“upper” and “lower are used to describe the various ele
FIG. 1A shows a bulk acoustic wave (BAW) resonator ments’ relationships to one another, as illustrated in the
fabricated in accordance with a representative embodiment. 25 accompanying drawings. It is understood that these relative
FIG. 1B shows a BAW resonator fabricated in accordanceterms are intended to encompass different orientations of thedevice and/or elements in addition to the orientation depictedwith a representative embodiment.
FIG. 2A shows a BAW resonator fabricated in accordancein the drawings. For example, if the device were inverted withrespect to the view in the drawings, an element described aswith a representative embodiment.
FIG. 2B shows a BAW resonator fabricated in accordance 30 “above' another element, for example, would now be belowthat element.
with a representative embodiment.
FIG. 3A shows a BAW resonator fabricated in accordance
Certain aspects of the present teachings are relevant tocomponents of FBAR devices, FBAR-based filters, theirwith a representative embodiment.
FIG. 3B shows a BAW resonator fabricated in accordancematerials and their methods of fabrication. Many details of
35 FBARs, materials thereof and their methods of fabrication
with a representative embodiment.
FIG. 4 shows a simplified schematic diagram of a deposi may be found in one or more of the following U.S. Patents andtion system in accordance with a representative embodiment. Patent Applications: U.S. Pat. No. 6,107,721, to Lakin: U.S.
FIG. 5 shows a flow-chart of a method of fabricating a Pat. Nos. 5,587,620, 5,873,153 and 6,507.983 to Ruby, et al.:piezoelectric layer in accordance with a first representative U.S. patent application Ser. No. 1 1/443,954, entitled “Piezo
embodiment.

40

FIG. 6 shows a flow-chart of a method of fabricating a
piezoelectric layerinaccordance with a second representativeelectric Resonator Structures and Electrical Filters' to Rich

ard C. Ruby, et al.; U.S. patent application Ser. No. 10/990,
201, entitled “Thin Film Bulk Acoustic Resonator with Mass

Loaded Perimeter to Hongjun Feng, et al.; and U.S. patent
FIG. 7 shows a graph of the coupling coefficient versus application Ser. No. 1 1/713.726, entitled “Piezoelectrichydrogen flow rate during the forming of a piezoelectric 45 Resonator Structures and Electrical Filters having Frame Elelayer.
ments' to Jamneala, et al.; and U.S. patent application Ser.
embodiment.

No. 11/159,753, entitled 'Acoustic Resonator Performance

Enhancement Using Alternating Frame Structure' to Richard
C. Ruby, et al. The disclosures of these patents and patent
It is to be understood that the terminology used herein is for 50 applications are specifically incorporated herein by referpurposes of describing particular embodiments only, and is ence. It is emphasized that the components, materials andnot intended to be limiting. The defined terms are in addition method of fabrication described in these patents and patentto the technical and Scientific meanings of the defined terms applications are representative and other methods of fabrica
as commonly understood and accepted in the technical field tion and materials within the purview of one of ordinary skill
55 in the art are contemplated.
of the present teachings.
Generally, the present teachings relate to a method of fab
As used in the specification and appended claims, the termsa’, ‘an and the include both singular and plural referents, ricating a piezoelectric layer comprising a selected C-axis
unless the context clearly dictates otherwise. Thus, for orientation (i.e., polarity). In certain embodiments a piezo
electric material fabricated according to representative
example, a device includes one device and plural devices.
As used in the specification and appended claims, and in 60 embodiments comprises a Cy polarity (also referred to asaddition to their ordinary meanings, the terms substantial or type-C piezoelectric material), whereas another piezoelec
substantially mean to with acceptable limits or degree. For tric material fabricated over the same Substrate comprises a
example, Substantially cancelled means that one skilled in C. polarity (also referred to as type-C, piezoelectric mate
the art would consider the cancellation to be acceptable.
rial). In other embodiments, more than two or more piezo
As used in the specification and the appended claims and in 65 electric layers are fabricated according to representative
addition to its ordinary meaning, the term approximately
embodiments comprise Cy polarity. Furthermore, in repremeans to within an acceptable limit or amount to one having sentative embodiments the piezoelectric material comprises
DEFINED TERMINOLOGYUS 9.243,316 B2
5
6
layer
104
of
type-C.
AIN.
In
a representative embodiment,
AlN. It is emphasized that this is merely illustrative, and thatthe fabrication of other types of piezoelectric materials is the seed layer 108 has a thickness in the range of approxi
contemplated, including but not limited to the fabrication of mately 50 A to approximately 1000 A over the upper surface
107. In other representative embodiments described below,
Zinc oxide (ZnO) and lead zirconium titanate (PZT).
Applications of the illustrative methods will be appreciated 5 the seed layer 108 is not provided over the first electrode 103.
by one having ordinary skill in the art. Some of these appli Rather, the type-Cypiezoelectric layer 104 is formed over thecations include FBARs useful intransformer applications and upper surface 107 of the first electrode 103 by methods of
FBARs useful infilter applications. For example, the method representative embodiments.
of fabrication piezoelectric materials comprising antiparallel
FIG. 1B shows a simplified cross-sectional view of an
C-axes (e.g., Cy polarity and C. polarity) may be useful on 10 FBAR 109 in accordance with another representative
the fabrication of film acoustic transformers, such as
embodiment. The acoustic stack 102 is provided over thedescribed in commonly owned U.S. Pat. Nos. 6,987,433 and substrate 101 and comprises the first electrode 103 disposed
7,091,649, to Larson, III, et al. Moreover, the method of over the substrate 101; the piezoelectric layer 104 disposed
fabrication piezoelectric materials comprising antiparallel over the first electrode 103; and the second electrode 105
C-axes (e.g., Cy polarity and C. polarity) or parallel C-axes 15 disposed over the piezoelectric layer 104. The substrate 101(e.g., both Cypolarity) may be useful in the fabrication of the illustratively comprises single-crystal silicon (Si), and com
stacked thin film bulk acoustic resonators (SBARs). SBARs prises an acoustic isolator 110 formed therein and disposedcomprise stacking two or more layers of piezoelectric mate beneath the first electrode 103. The acoustic isolator 110 may
rial with electrodes between the piezoelectric layers and on be a known acoustic mirror comprising layers of alternating
the top and bottom of the stack. Such SBARs are described, high acoustic impedance material and low impedance matefor example in commonly owned U.S. Pat. Nos. 5,587,620 rial. The piezoelectric layer 104 illustratively comprises AlN.
and 6,060.818, to Ruby, et al. Furthermore, the method of and is a type-Cy material fabricated in accordance with thefabricating piezoelectric materials comprising antiparallel present teachings.
C-axes (e.g., C. polarity and C. polarity) or both comprising
In a representative embodiment, the FBAR 109 comprises
Cy polarity may be useful in CRF applications, such as 25 the seed layer 108 disposed over an upper surface 107 of thedescribed in commonly-owned U.S. patent application Ser. first electrode 103. The seed layer 108 has a thickness in theNo. 12/201,641 entitled “Single Cavity Acoustic Resonators range of approximately 50 A to approximately 1000 A overand Electrical Filters Comprising Single Cavity Acoustic the upper surface 107. In other representative embodiments
Resonators' filed on Aug. 29, 2008 to Bradley, et al.; and in described below, the seed layer 108 is not provided over thecommonly owned U.S. Pat. No. 7,515,018 to Handtmann, et 30 first electrode 103. Rather, the type-C piezoelectric layer
al. The disclosures of U.S. Pat. Nos. 5,587,620; 6,060,818;
104 is formed over the upper surface 107 of the first electrode6,987,433; 7,091649; and 7,515,018 and the disclosure of 103 by methods of representative embodiments.
U.S. patent application Ser. No. 12/201,641 are specifically
FIG. 2A shows a simplified cross-sectional view of anincorporated herein by reference. It is emphasized that the FBAR200 in accordance with a representative embodiment.
noted applications are intended merely to illustrate applica 35 The acoustic stack 102 is provided over the substrate 101 andtions of the methods of the present teachings, and that the comprises the first electrode 103 disposed over the substrateapplication of the methods of fabricating piezoelectric mate
101; the piezoelectric layer 104 disposed over the first elec
rials of the present teachings are not limited to these illustra trode 103; and the second electrode 105 disposed over thetive applications.
piezoelectric layer 104. The piezoelectric layer 104 is a type
FIG. 1A shows a simplified cross-sectional view of an 40 Cypiezoelectric material, and is illustratively type-Calumi
FBAR 100 in accordance with a representative embodiment. num nitride (AIN). The substrate 101 illustratively comprises
An acoustic stack 102 is provided over a substrate 101 and single-crystal silicon (Si).
comprises a first electrode 103 disposed over the substrate
The cavity 106 is formed in the substrate 101 beneath the101; a piezoelectric layer 104 disposed over the first electrode first electrode 103 by a known method. The first electrode 103
103; and a second electrode 105 disposed over the piezoelec 45 and the second electrode 105 may be one of a variety oftric layer 104. The piezoelectric layer 104 is a type-C piezo conductive materials as noted above, and are fabricated using
electric material, and is illustratively type-C aluminum a known method. The piezoelectric layer 104 is fabricated innitride (AIN). The substrate 101 illustratively comprises accordance with the present teachings.
single-crystal silicon (Si).
In a representative embodiment, and unlike the FBAR100.
A cavity 106 is formed in the substrate 101 beneath the first 50 FBAR 200 does not comprise the seed layer 108 over theelectrode 103 by a known method. The first electrode 103 and upper surface 107 of the first electrode 103. Rather, the typethe second electrode 105 may be one of a variety of conduc Cy piezoelectric layer 104 is formed over the upper surface
107 of the first electrode 103 by methods of representative
tive materials, such as metals suitable as electrodes in BAW
applications. Generally, materials suitable for the first elec embodiments described below.
trode 103 and the second electrode 105 comprise Refractory 55 FIG. 2B shows a simplified cross-sectional view of an
metals. Transition metals or Noble Metals. In specific FBAR 201 in accordance with a representative embodiment.
embodiments, the first and second electrodes 103, 105 illus
The acoustic stack 102 is provided over the substrate 101 andtratively comprise one or more of molybdenum (Mo), alumi comprises the first electrode 103 disposed over the substrate
101; the piezoelectric layer 104 disposed over the first elecnum (Al), tungsten (W), platinum (Pt), ruthenium (Ru), nio
bium (Nb), hafnium (Hf) and uranium-238 (U-238), or other 60 trode 103; and the second electrode 105 disposed over the
low-loss metals, and are fabricated using a known method. piezoelectric layer 104. The substrate 101 illustratively com
The piezoelectric layer 104 is fabricated in accordance with prises single-crystal silicon (Si), and comprises the acoustic
the present teachings.
isolator 110 formed therein and disposed beneath the firstIn a representative embodiment, the FBAR 100 comprises electrode 103. The acoustic isolator 110 may be a known
a seed layer 108 disposed over an upper surface 107 of the first 65 acoustic mirror comprising layers of alternating high acoustic
electrode 103. As described more fully below, the seed layer impedance material and low impedance material. The first
108 is illustratively Al and fosters growth of piezoelectric electrode 103 and the second electrode 105 may be one of aUS 9.243,316 B2
8piezoelectric layers with Cyaxes by providing a seed layerover a Surface of respective electrodes and forming therespective piezoelectric layer thereover.
Furthermore, in certain BAW structures comprising an
acoustic resonator comprising more than one piezoelectric
layer, it is desirable to provide piezoelectric layers compris
ing anti-parallel C-axes (e.g., one type C piezoelectric layer,
and one type C piezoelectric layer). The present teachings
embodiments described below.
also contemplate forming the piezoelectric layers with Cy
FIG.3A shows a simplified cross-sectional view of a BAW 10 axes by providing a seed layer over the Surface of an elec
resonator 300 in accordance with a representative embodi trode, forming the type Cy piezoelectric layer over the seed
ment. The BAW resonator 300 comprises a single cavity such layer and forming a type C piezoelectric layer over anotheras described in commonly-owned U.S. patent application Ser. electrode. The type C piezoelectric layer is formed using a
No. 12/201,641 to Bradley, et al. The BAW resonator 300 known method.
comprises a first electrode 303 disposed over a substrate 301; 15 FIG.3B shows a simplified cross-sectional view of a BAW
a first piezoelectric layer 304 disposed over the first electrode resonator 302 in accordance with a representative embodi
303; and a second electrode 305 disposed over the first piezo ment. The BAW resonator 302 comprises a single cavity suchelectric layer 304. In the representative embodiment, the first as described in commonly-owned U.S. patent application Ser.
piezoelectric layer 304 is a type-C piezoelectric material, No. 12/201,641 to Bradley, et al. The BAW resonator 302
and is illustratively type-C aluminum nitride (AIN). The comprises first electrode 303 disposed over substrate 301;
substrate 301 illustratively comprises single-crystal silicon first piezoelectric layer 304 disposed over the first electrode303; and second electrode 305 disposed over the first piezo(Si).
A second piezoelectric layer 311 is disposed over the sec electric layer 304. In a representative embodiment, the first
ond electrode 305; and a third electrode 312 is disposed over piezoelectric layer 304 is a type-C piezoelectric material,
the second piezoelectric layer 311. The second piezoelectric 25 and is illustratively type-C aluminum nitride (AIN). The
layer 311 is a type-C piezoelectric material, and is illustra substrate 301 illustratively comprises single-crystal silicon
tively type-C aluminum nitride (AIN). A cavity 306 is (Si).
The second piezoelectric layer 311 is disposed over theformed in the substrate 301 beneath the first electrode 303 bya known method. The cavity 306 provides acoustic isolation second electrode 305; and the third electrode 312 is disposed
as described above. Alternatively, an acoustic isolator (not 30 over the second piezoelectric layer 311. The second piezo
shown in FIG. 3A) such as described above and comprising electric layer 311 is a type-C piezoelectric material, and isalternating layers of comparatively high and low acoustic illustratively type-Caluminum nitride (AIN). Cavity 306 is
impedance may be used instead of the cavity 306.
formed in the substrate 301 beneath the first electrode 303 bya known method. The cavity 306 provides acoustic isolation
The first electrode 303, the second electrode 305 and thethird electrode 312 may be one of a variety of conductive 35 as described above. Alternatively, an acoustic isolator (notmaterials, such as metals suitable as electrodes in BAW appli shown in FIG. 3B) such as described above and comprising
cations. Generally, materials suitable for the first electrode alternating layers of comparatively high and low acoustic
103 and the second electrode 105 comprise Refractory met impedance may be used instead of the cavity 306.
The first electrode 303, the second electrode 305 and theals, Transition metals or Noble Metals. In specific embodi
ments, the first and second electrodes 103,105 illustratively 40 third electrode 312 may be one of a variety of conductive
comprise one or more of molybdenum (Mo), aluminum (Al), materials, such as metals suitable as electrodes in BAW appli
tungsten (W), platinum (Pt), ruthenium (Ru), niobium (Nb), cations. Generally, materials suitable for the first electrode103 and the second electrode 105 comprise Refractory met
hafnium (Hf) and uranium-238 (U-238), or other low-loss
metals, and are fabricated using a known method. The piezo als, Transition metals or Noble Metals. In specific embodi
electric layer 104 is fabricated in accordance with the present 45 ments, the first and second electrodes 103,105 illustratively
teachings.
comprise one or more of molybdenum (Mo), aluminum (Al),In a representative embodiment, the FBAR 300 comprises tungsten (W), platinum (Pt), ruthenium (Ru), niobium (Nb),a first seed layer 308 disposed over an upper surface 307 of the hafnium (Hf) and uranium-238 (U-238), or other low-loss
first electrode 303; and a second seed layer 310 disposed over metals, and are fabricated using a known method. The piezo
an upper surface 309 of the second electrode 305. As 50 electric layer 104 is fabricated in accordance with the present
described more fully below, the first and second seed layers teachings.
308,310 are illustratively Al and foster growth of the first andIn a representative embodiment, and unlike FBAR 300
second piezoelectric layers 304,311 both of type-C. AlN. In shown in FIG.3A, the FBAR302 does not comprise either thea representative embodiment, the first and second seed layers first seed layer 308 over an upper surface 307 of the first
308,310 each have a thickness in the range of approximately 55 electrode 303, or the second seed layer 310 disposed over an
50 A to approximately 1000 A.
upper surface 309 of the second electrode 305. Rather, (theIt is appreciated that the FBAR 300 of the representative type-C) first and second piezoelectric layers 304, 311 areembodiment comprises an acoustic stack comprising more formed over upper surface 307 and 309 of the first electrodethan one type Cy piezoelectric layer. It is emphasized that 303 and the second electrode 305, respectively, by methods ofother BAW resonator structures comprising an acoustic stack 60 representative embodiments described below.
comprising more than one type C piezoelectric layer are
It is appreciated that the FBAR 302 of the representative
contemplated. For example, decoupled Stacked acoustic reso embodiment comprises an acoustic stack comprising morenators comprising more than one FBAR with an acoustic than one piezoelectric layer having a Caxis. It is emphasizeddecoupler disposed therebetween are contemplated. In Such that other BAW resonator structures comprising an acoustic
an embodiment, each of the FBARs would include a type Cy 65 stack comprising more than one type Cy piezoelectric layer
piezoelectric layer fabricated in accordance with the present are contemplated. For example, decoupled Stacked acoustic
teachings. The present teachings contemplate forming the resonators comprising more than one FBAR with an acoustic
7
variety of conductive materials as noted above, and are fab
ricated using a known method. The piezoelectric layer 104 isfabricated in accordance with the present teachings.
In a representative embodiment, and unlike FBAR 109
shown in FIG. 1B, the FBAR 201 does not comprise the seedlayer 108 over the first electrode 103. Rather, the type-C
piezoelectric layer 104 is formed over the upper surface 107of the first electrode 103 by methods of representativeUS 9.243,316 B2
910
decoupler disposed therebetween are contemplated. In Such provided by selectively sputtering the first and second targets
an embodiment, each of the FBARs would include a type Cy 4.09.410 (e.g., Al) in an Ar/N atmosphere, from gas outlets
piezoelectric layer fabricated in accordance with the present 406, 407.
teachings. The present teachings contemplate forming the
In another exemplary method where no seed layer is pro
type Cypiezoelectric layers over a Surface of respective elec vided, hydrogen (H2) is provided from one of the gas outlets
trodes. Furthermore, in certain BAW structures comprising 406, 407 to provide a hydrogen atmosphere useful in remov
an acoustic resonator comprising more than one piezoelectric ing contaminants on the upper Surface 107. The contaminants
layer, it is desirable to provide piezoelectric layers compris could include metal oxides, gases such as H2O, N, or O on
ing anti-parallel C-axes (e.g., one type C piezoelectric layer, the upper Surface 107, as well as processing residues such as
and one type C piezoelectric layer). The present teachings 10 photoresist. After the cleaning step in the hydrogen atmo
also contemplate forming the piezoelectric layers with Cy sphere, the growth of type-Cypiezoelectric layer (e.g., piezoaxes and forming a type C piezoelectric layer over another electric layer 104) is provided by selectively sputtering theelectrode. The type C piezoelectric layer is formed using a first and second targets 409, 410 (e.g., Al) in an ArfN/H
known method.
atmosphere, from gas outlets 406, 407408 or by pre-mixed
FIG. 4 shows a simplified schematic diagram of a deposi 15 Source of Ar/H2, and a nitrogen source.
Turning to FIG. 5, a method 500 of fabricating a piezoelection system 400 in accordance with a representative embodi
ment. The deposition system 400 comprises components tric layer in accordance with a representative embodiment iscommercially available from Advanced Modular Systems,
shown in a simplified flow-chart. The method 500 is
Inc. of Santa Barbara, Calif. USA, for example. In represen described with direct reference to the components of FIGS.
tative embodiments, the deposition system 400 is a sputter 1A, 1B and the deposition system 400 of FIG. 4 for illustrative
deposition system, many of the components and dynamics of purposes. Fabrication of other FBAR structures, such as
which are known to one of ordinary skill in the art. Because FBAR 300, using the method 500, is also contemplated. As
many details of the deposition system 400 and Sputtering will become clearer as the present description continues, thetechniques are known, many details are not provided to avoid method 500 provides a seed layer 108 over the first electrodeobscuring the description of the representative embodiments. 25 103 in the formation of type-C piezoelectric layer 104. As
The deposition system 400 comprises a reaction chamber alluded to above, the method 500 may be used to provide first
401, which is maintained Substantially at vacuum during fab seed layer 308 over the first electrode 303 and the second seedrication of piezoelectric materials of the representative layer 310 over the second electrode 305 of the BAW resonator
embodiments. The deposition system 400 also comprises gas 300 by repeating the process after forming the intervening
inlets 403, 404, 405 as inputs to a flow control system 402, 30 layer(s) of the BAW resonator 300.
At 501, the method comprises forming a first electrodewhich controls the flow of selected gases provided to the gas
inlets 403, 404, 405 and the flow rates of the gases provided. over a substrate. Illustratively, the first electrode 103 is
A load and lock chamber 413 is provided to allow for the formed over the substrate 101. For purposes of description ofloading of wafers and transfer them to a reaction chamber 401 the method 500, the first electrode 103 is formed by sputter
withoutbreaking vacuum. The flow control system 402 com 35 depositing the selected conductive material over the substrateprises valves (not shown) for selecting the gases to be flowed 101 by a known method, although other methods of forming
into the reaction chamber 401, flow controllers (not shown) to the first electrode are contemplated. Notably, the formation of
measure and control the flow rates thereof, and a controller
the cavity 106 in the substrate 101 may be carried out before(not shown) comprising Suitable Software for controlling the fabrication of the acoustic stack 102 of the FBAR 100, withvalves. Moreover, the deposition system 400 may comprise 40 the cavity 106 filled with a sacrificial material (not shown)
Such as phosphosilicate glass (PSG) or other release pro
an exhaust outlet 412, which has a constant pumping speed,and control of the total pressure in the reaction chamber 401 cesses such as polysilicon and Xenon difluoride etchant,is provided by changing of gas flow by each flow controller known to one of ordinary skill in the art, during the fabrication
independently or together.
of layers of the acoustic stack 102; and released after the
The flow control system 402 may comprise an interface 45 forming of the layers of the acoustic stack 102. Alternatively,(not shown). Such as a graphic user interface (not shown). The the acoustic isolator 110 is formed in the substrate 101 before
deposition system 400 also comprises gas outlets 406, 407, forming of the first electrode 103 of the FBAR 109.
The fabrication of the piezoelectric layer 104 begins with
408, from the flow control system 402. Gas from the gas
outlets 406, 407,408 is provided to the reaction chamber 401. cleaning the upper surface 107 of the first electrode 103
Notably, the use of mixed gases (e.g., Arand H2) from a single 50 before the forming of the piezoelectric layer 104. In a repre
sentative embodiment, this cleaning step comprises flowing
source is also contemplated. As described more fully below,
these gases form atmospheres used in cleaning and sputter only Arto one of the gas inlets 403, 404.405 and to one of thedepositing materials 411 from first target 409 and second gas outlets 406, 407 to provide an Ar atmosphere in thetarget 410 over the substrate 101 according to representative reaction chamber 401. An RF bias is applied to the first
embodiments.

55

electrode 103 and the reaction chamber 401 is maintained at

As described in connection with representative embodi ground, so that the first electrode 103 functions as a cathode.
ments below, the gas inlets 403, 404, 405 may selectively An Ar plasma is formed in the reaction chamber 401 andprovide argon (Ar), nitrogen (N) or hydrogen (H), respec bombards the upper surface 107 of the first electrode 103.
tively, or a combination thereof. The gas outlets 406, 407,408 Illustratively, the RF power is provided in the range ofprovide a mixture of these gases as to the reaction chamber 60 approximately 15 W to approximately 1 kW, and the Ar
401. For example, informing an Al seed layer (e.g., seed layer bombardment of the upper surface 107 of the first electrode is108), Ar plasma may be formed by the outlet of Argas from maintained for a few seconds to a few minutes to ensure
one of the gas outlets 406, 407 in the reaction chamber 401, proper removal of contaminants. Notably, during this clean
and results in sputter deposition of seed layer 108 of Al from ing step, no voltage is applied to the first and second targets
first and second Al targets 409, 410 over the first electrode 65 409, 410.
It is believed that the comparatively high kinetic energy of103. After the forming of the seed layer 108, the growth of
type-C piezoelectric layer (e.g., piezoelectric layer 104) is the Arions provides suitable bombardment of the upper surUS 9.243,316 B2
11face 107 to remove substantially therefrom contaminants

12
to Substantially prevent adsorption of oxides and nitrides orsuch as adsorbed water, adsorbed oxide, adsorbed nitrides
the formation of other contaminants over the exposed Surface
and native oxides formed on materials commonly used in the (s) of the seed layer 108.
fabrication of the first electrode 103. By substantially remov
It is believed that because the Al seed layer 108 is com
ing contaminants from the upper surface 107, the formation paratively free from contaminants due to the cleaning step inof a comparatively pure and electropositive Al seed layer 108 Ar, a substantially electropositive surface of Al is formed overis fostered. Thereafter, a type-CAIN piezoelectric layer may the upper surface 107 of the first electrode 103. The Al seed
be formed by deposition of AlN over the seed layer 108 as layer 108 is comparatively highly reactive, and attracts nitro
described above. Furthermore, in an embodiment where thegen of the sputtered AlN. As such, it is believed that AlN isfirst electrode 103 comprises Pt, by this cleaning step in the Ar 10 oriented with the nitrogen bonded to the electropositive seedatmosphere, it is believed that contaminants such as adsorbed layer of aluminum, and the aluminum of the AlN not being
bonded is exposed (i.e., in a structure: seed layer-NA1). Sputwater, adsorbed oxides and adsorbed nitrides are believed tobe removed from the Pt, which does not readily form native tered AlN is then bonded to the exposed aluminum, with theoxides.
nitrogen bonded to the exposed aluminum (i.e., in a structure:
At 502, the method 500 comprises forming the seed layer 15 seed layer-N-AL-N-AL). This sequence results in the form
108 over the upper surface 107 of the first electrode 103. In a ing of the crystal structure of type-CAIN piezoelectric mate
representative embodiment, at this point the RF power to the rial, and continues until a Suitable thickness of the type-C
first electrode 103 is terminated, and AC power is provided AlN (e.g., piezoelectric layer 104) is realized. In one embodi
between the first target 409 and the second target 410 in the ment, the AlN layer has a thickness of approximately 12,000
reaction chamber 401. In a representative embodiment, the A.
piezoelectric material comprises two components, and the
The flow rates of Arand N are set to control the stress offirst and second targets 409, 410 comprise one of the compo the resultant AlN. Notably, a higher flow rate of Arresults in
nents. Illustratively, AlN is the piezoelectric material, and the tensile stress in the AlN; a lower the flow rate of Arresults infirst and second targets 409,410 comprise Al. Aluminum is compressive stress in the AlN. Similarly, a higher the flow rate
sputtered from the first and second targets 409,410 during the 25 of N results intensile stress in the AlN; and a lower flow rate
negative potential half-cycle of AC power applied to the first of N results in compressive stress in the AIN. In representa
and second targets 409,410 and provides seed layer 108 over tive embodiments, the flow rate of Ar is in the range ofthe upper surface 107 of the first electrode 103. During the approximately 6 sccm to approximately 25 sccm, and the flow
forming of the seed layer 108, Ar is flowed to one of the gas rate of N is in the range of approximately 39 scem to approxi
inlets 403, 404, 405 and from one of the gas outlets 406, 407; 30 mately 50 sccm.
After the piezoelectric layer 104 is formed, the secondand no other gases are flowed from the other gas outlet 406,
407. As a result, Ar plasma created in the reaction chamber electrode 105 is formed over the piezoelectric layer 104. The
401 results in the sputter deposition of a substantially pure second electrode 105 comprises a metal that is sputter-depos
aluminum seed layer from the first and second targets 409, ited over the piezoelectric layer 104 by a known method.
410 and over the upper surface 107 of the first electrode 103. 35 Illustratively, the second electrode 105 comprises the same
Notably, the longer AC power is applied between the first and material as the first electrode 103. Notably, different materials
second targets 409,410, the thicker the seed layer 108 that is may be used for the electrodes as may be beneficial to theformed.
FBAR (BAW resonator) 100.
After the forming of the second electrode 105, the release
At 503, and after the seed layer 108 is formed, the method
500 comprises flowing a first component of the piezoelectric 40 of the sacrificial material to form the cavity 106 is carried out
layer and sputtering the piezoelectric layer 104 over the sub using a Suitable etchant such as HF. As should be appreciated,strate 101. In a representative embodiment used to form AlN. if unprotected the seed layer 108 may be etched by the etchantthe first component comprises nitrogen (N) gas. The flowing as well. In order to prevent this from significantly deteriorat
of nitrogen into the reaction chamber 401 comprises provid ing the seed layer 108, a protective layer (not shown) overing nitrogen to one of the gas inlets 403, 404, 405 and from 45 and/or around the acoustic stack 102 comprising the firstone of the gas outlets 406, 407,408, while continuing the flow electrode 103, the seed layer 108, the piezoelectric layer 104
of Arto another of the gas inlets 403, 404, 405 and from the and the second electrode 105. The protective layer may com
other of the gas outlets 406, 407, 408. During the flowing of prise a metal dam formed from the same metal as the first
nitrogen, AC power is Supplied between the first and second and second electrodes 103, 105, for example; or may betargets 409,410, which comprise the second component (e.g., 50 formed of a material impervious to the etchant (e.g., HF).
Al) of the piezoelectric material (e.g., AlN), and the piezo Such protective layers are formed by known deposition,
electric material is formed over the surface of the first andlithography and etching sequences. Alternatively, a compara
second targets 409,410. In a representative embodiment, the tively thin (e.g., 50 A) seed layer 108 may be provided. It is
AC power has a frequency in the range of approximately 20 believed that a comparatively thin seed layer will not be
kHz to approximately 100 kHz, and power in the range of 55 appreciably etched by the etchant used to release the sacrifi
approximately 4 kW to approximately 7 kW. Illustratively, cial material from the cavity 106. Of course, if instead of thethe AC power has a frequency of 7 kW and a frequency of 40 cavity 106, the acoustic isolator 110 is implemented as in
kHZ.

FBAR 109, the release of sacrificial material and thus the

The Ar? N plasma is maintained, and sputters the AlN from passivation material would not be necessary.
the first and second targets 409,410 to the seed layer 108, in a 60 The FBARs 100, 109 described in connection with thepreferred orientation to provide type C. AIN over the seed method 500 comprise a single piezoelectric layer. As noted
layer 108. Beneficially, the depositing of the piezoelectric above, the acoustic stack of certain resonator structures com
layer 104 in the portion of the method is effected without prises more than one piezoelectric layer. It is emphasized thatbreaking vacuum conditions in the system 400, and compara the method 500 can be repeated to form a second type-CAIN
tively rapidly after completion of the forming of the seed 65 piezoelectric layer. For example, by repeating the method
layer 108. Maintaining vacuum and relatively rapidly begin 500, BAW resonator 300 comprising first and second piezoning the deposition of the piezoelectric layer 104 is believed electric layers 304, 311 is fabricated by forming first andUS 9.243,316 B2
13second seed layers 308, 310 respectively over respective
upper surfaces 307,309 of first and second electrodes 303,

14
maintained for a few seconds to a few minutes to ensure

proper removal of contaminants. Notably, during this clean
ing step, no voltage is applied to the first and second targets
In certain applications, two or more piezoelectric layers 4.09.410; and therefore sputtering of material (e.g., Al) frommay be included in the acoustic stack, and have opposing 5 first and second targets 409,410 is insignificant. As such, andC-axes. For example, in an acoustic stack described U.S. Pat. in contrast to the method 500, no seed layer (e.g., seed layer
No. 7,515,018, the C-axes of the piezoelectric layers may be 108) is formed over the upper surface 107 of the first electrodeantiparallel. As can be appreciated, in a structure comprising 103.
two piezoelectric layers in an acoustic stack, the first piezo
The hydrogen plasma formed in the reaction chamber 401
electric may be type-C piezoelectric material (e.g., first 10 bombards the upper surface 107 of the first electrode 103. The
piezoelectric layer 304), and the second piezoelectric layer flow of H in 402 provides ionized hydrogen (e.g., Ha' or H')
311 may be type-C piezoelectric material. In Such an in the reaction chamber 401 that provides a reducing agent at
embodiment, the deposition system 400 and method 500 the upper surface 107. The ionized hydrogen is believed to
could be used to form the type-C piezoelectric layer by react with many contaminants such as water, adsorbed
method 500, and the type-C, piezoelectric layer would be 15 oxides, nitrides and native oxides that may be present on theformed by a known method using deposition system 400. For upper surface 107, and fosters their removal to provide a
example, the first electrode 103 may be formed as described comparatively clean surface. Moreover, it is believed that thein 501 above; and the C piezoelectric layer may beformed by ionized hydrogen forms metal hydrides by Saturating dan
flowing the first component of the piezoelectric material as gling bonds on the surface of the metal of the first electrodedescribed in 503 above. Notably, in forming a C piezoelec 103. Furthermore, in an embodiment where the first electrode
tric layer, the sequence of 502 is not performed.
103 comprises Pt, by the cleaning step with H, it is believed
FIG. 6 shows a flow-chart of a method 600 of fabricating a that contaminants such as adsorbed water, oxides and nitrides
piezoelectric layer in accordance with a representative are believed to be removed on Pt, which does not readily form
embodiment. Many of the details of the method 600 are native oxides. Notably, however, because no electrical potencommon to the method 500, and may not be repeated in order 25 tial is applied to the first and second targets 409,410 during602, Al is not appreciably sputtered from the first and second
to avoid obscuring the presently described embodiments.
The method 600 is described with direct reference to thetargets 409,410.
components of FIGS. 2A, 2B and the deposition system 400
At 603 the method 600 comprises flowing a first compoof FIG. 4 for illustrative purposes. Fabrication of other FBAR nent of the piezoelectric layer 104. In a representative
structures, such as FBAR 302, using the method 600, is also 30 embodiment used to form AlN, the first component comprises
contemplated. As will become clearer as the present descrip nitrogen (N) gas. The flowing of nitrogen into the reaction
chamber 401 comprises providing nitrogen to one of the gastion continues, the method 600 may be used to form type-C
piezoelectric layer 104 over the upper surface 107 of the first inlets 403, 404, 405 and from one of the gas outlets 406, 407,
electrode 103. As alluded to above, the method 600 may be 408, while continuing the flow of Ar to another of the gas
used to provide the first piezoelectric layer 304 over the upper 35 inlets 403, 404, 405 and from the other of the gas outlets 406,
surface 307 of the first electrode 303 and the second piezo 407,408.
Notably, H may be provided to the same gas outlet 406,
electric layer 311 over the upper surface 309 of the second
electrode 305 of the BAW resonator 302 by repeating the 407, 408 that provides Ar; or a separate outlet (not shown)process after forming the intervening layer(s) of the BAW may be provided into the reaction chamber to provide an
resonator 302.
40 Ar/N/H atmosphere. Alternatively, after the completion of
At 601 the method comprises providing a substrate. Illus 602, hydrogen flow may be terminated. The flow rates of Ar
tratively, the substrate formed in 601 comprises first electrode and N are set to control the stress of the resultant AIN. As
103, which is formed over the substrate 101. For purposes of described previously, a higher the flow rate of Ar results in
description of the method 600, the first electrode 103 com tensile stress in the AlN; and a lower the flow rate of Arresults
prises a metal that is sputter-deposited over the substrate 101 45 in compressive stress in the AIN. Similarly, a higher the flowby a known method. Notably, the formation of the cavity 106 rate of N results in tensile stress in the AlN; and a lower thein the substrate 101 may be carried out before fabrication of flow rate of N results in compressive stress in the AlN. In
the layers of the acoustic stack 102 of FBAR 100, with the representative embodiments, the flow rate of Aris in the range
cavity 106 filled with a sacrificial material (not shown) such of approximately 6 scem to approximately 25 Scem, and theas phospho-silicate glass (PSG) during the fabrication of 50 flow rate of N is in the range of approximately 39 sccm tolayers of the acoustic stack 102, and released after forming approximately 50 sccm.
During the flowing of nitrogen, AC power is Supplied
the layers of the acoustic stack 102. Alternatively, the acoustic
isolator 110 is formed in the substrate 101 before forming of between the first and second targets 409,410, and AlN H
the first electrode 103 of FBAR 109.
compounds are formed over the surface of the first and second
At 602, the fabrication of the piezoelectric layer 104 begins 55 targets 409,410. Moreover, NH, compounds are believed towith cleaning an upper surface 107 of the first electrode 103 beformed in the reaction chamber 401. It is believed that NH
before the forming of the piezoelectric layer 104. In a repre compounds formed in the reaction chamber 401 fosters thesentative embodiment, this cleaning step comprises flowing formation of form an AlN-H compound, due to reactions on
Arand H to respective gas inlets 403, 404.405 and from one the surface of the first and second targets 409,410 between Alof the gas outlets 406, 407, 408. An RF bias is applied to the 60 and NHX.
first electrode 103 and the reaction chamber 401 is main
The greater the frequency of the AC power, the lower thetained at ground, so that the first electrode 103 functions as a deposition rate of AlN. Accordingly, the frequency of the AC
cathode. As in method 500, an Ar plasma is formed and power generally should not exceed 100 kHz. Notably, if thebombards the upper surface 107 of the first electrode 103. flow of hydrogen is maintained during 603, the cleaning
Illustratively, the RF power is provided in the range of 65 action of hydrogen is realized, but due to its comparatively
approximately 15 W to approximately 1 kW, and the Ar Small atomic mass, hydrogen does not appreciably sputter
bombardment of the upper surface 107 of the first electrode is Al N from the first and second targets 409,410.
305.

US 9.243,316 B2
15
16
secondpiezoelectric
layer
304),
and the second piezoelectric
At 604 piezoelectric material is sputtered from the first andsecond targets 409,410 over the substrate 101. In a specific layer 311 may be type-C, piezoelectric. In such an embodi
embodiment, AlN H formed on the first and second targets ment, the deposition system 400 would be used to form the409,410 is sputtered to the upper surface 107 of the first type-C piezoelectric layer by method 600, and the type-C
electrode 103. The metal hydrides formed at the upper surface piezoelectric layer would be formed by a known method
107 are believed to present an electronegative surface that using deposition system 400.
If the second piezoelectric layer (e.g., second piezoelectric
attracts the aluminum of the AlN H sputtered from thetarget. Accordingly, the desired orientation (i.e., metal layer 311) is type-C. AlN, the cleaning step of method 600
hydride-AlN—AlN—AlN) to form the crystal structure of would be carried out to remove contaminants from the elec
type-C. AlN piezoelectric material is provided and 603 con 10 trode over which the second piezoelectric layer is formed(e.g., second electrode 305). If there is no intervening acous
tinues until a Suitable thickness of the type-C. AlN (e.g.,piezoelectric layer 104) is realized. In one embodiment, the tic decoupling layer or intervening electrode, the cleaning
AIN layer has a thickness of approximately 12,000 A.
step of the method 600 would be carried out to remove con
It is believed that hydrogen gas molecules (H) and atoms taminants from the surface (e.g., upper surface 309) of the(H) attach to the AlN on the surface of the metal of the first 15 second electrode 305. The forming of the second piezoelec
electrode 103. The hydrogen atoms then penetrate into the tric layer would be effected by repeating 603 of the methodinterior next to Al side of AlN molecule to forman aluminum

600.

In certain applications, two or more piezoelectric layers
hydride-nitride substance. The AlN molecules are stretchedapart to accommodate the hydrogen atoms. The physical may be included in the acoustic stack, and have opposing
structure of the H-AIN molecule may also change. Then as C-axes. For example, in the acoustic stacks described in U.S.
a result of adsorption, the hydrided part of H AlNaligns and patent application Ser. No. 12/201,641 and U.S. Pat. No.
migrates to the surface of the metal hydride formed on the first 7,515,018, the C-axes of the piezoelectric layers may beelectrode 103, combines into hydrogen molecules H and antiparallel. As can be appreciated, in a structure comprising
two piezoelectric layers in an acoustic stack, the first piezo
pulls the Al part of AlN toward to first electrode 103.
As noted above, the H. flow into the reaction chamber 401 25 electric may be type-Cy (e.g., first piezoelectric layer 304),
may be continuous during the forming of the piezoelectric and the second piezoelectric layer (e.g., second piezoelectricmaterial. As described above, it is believed that the presence layer 311) may be type-C. In such an embodiment, theof ionized hydrogen in the reaction chamber provides a reduc deposition system 400 would be used to form the type-C
ing agent that can remove contaminants such as oxides, piezoelectric layer by method 600, and the type-C, piezoelec
nitrides and water, which can interfere with the forming of 30 tric layer would be formed by a known method using depo
type-C piezoelectric material, or can reduce the coupling sition system 400.

coefficient (kt) and therefore degrade the quality (Q) factor

FIG. 7 shows a graph of intrinsic coupling constant (kt)of the piezoelectric material, or both. In a representative versus Hydrogen flow rate of a piezoelectric layer fabricatedembodiment, the flow rate of H during the forming of the in accordance with a representative embodiment. In particu
AlN is at least approximately 8 sccm. In certain embodi 35 lar, in region 701 of the graph, the intrinsic coupling constant,ments, the flow rate of H during the forming of the AlN is as kt is indicative of indicative of CAIN formed in accordance
great as approximately 30 scem. Illustratively, a flow rate of with a representative embodiment. By contrast, in region 702,
H of approximately 14 scem provides a CAIN piezoelectric the intrinsic coupling constant, kt is indicative of Cy AIN
material with kt of approximately 5.5%. As described below, formed by a known method.

the coupling coefficientkt of AIN fabricated with continuous 40 In accordance with illustrative embodiments, methods offlow of H at the flow rates noted provides C. AlN piezoelec fabricating piezoelectric materials and acoustic resonators fortric material with kt of approximately 2% to approximately various applications such as in electrical filters are described.
6.6%. FIG. 7 shows the coupling coefficient versus hydrogen One of ordinary skill in the art appreciates that many varia
flow rate during the forming of the piezoelectric layer in 603. tions that are in accordance with the present teachings are
After the piezoelectric layer 104 is formed, the second 45 possible and remain within the scope of the appended claims.
electrode 105 is formed over the piezoelectric layer 104. The These and other variations would become clear to one ofsecond electrode 105 comprises a metal that is sputter-depos ordinary skill in the art after inspection of the specification,ited over the piezoelectric layer 104 by a known method. drawings and claims herein. The invention therefore is not toIllustratively, the second electrode 105 comprises the same be restricted except within the spirit and scope of thematerial as the first electrode 103.
50 appended claims.
The FBARs 200, 201 described in connection with themethod 600 comprise a single piezoelectric layer. As noted

The invention claimed is:

1. A method of fabricating a piezoelectric material com
prising a first component and a second component, theprises more than one piezoelectric layer. It is emphasized that method comprising:the method 600 may be repeated to form a second type-C 55 providing a Substrate;
AlN piezoelectric layer. For example, by repeating theinitially flowing hydrogen over the substrate;
after the initially flowing of the hydrogen over the sub
method 600 in a selected sequence, BAW resonator 302 com
prising first and second piezoelectric layers 304,311, respec
Strate,flowing the first component to form the piezoelectric matetively, are formed over respective upper surfaces 307, 309 of
60
rial over a surface of a target comprising the second
first and second electrodes 303, 305.
component;
In certain applications, two or more piezoelectric layers
sputtering the piezoelectric material from the target onto
may be included in the acoustic stack, and have opposing
the substrate; andC-axes. For example, in an acoustic stack described in U.S.
flowing the hydrogen over the Substrate during the Sputter
Pat. No. 7,515,018, the C-axes of the piezoelectric layers may
ingatarate Sufficient to cause apiezoelectric film having
be antiparallel. As can be appreciated, in a structure compris 65
ing two piezoelectric layers in an acoustic stack, the firsta defined polarity to be formed over the substrate,
whereinpiezoelectric may be type-C piezoelectric (e.g., first andabove, the acoustic stack of certain resonator structures com

US 9.243,316 B2
17
18
Sputtering the piezoelectric material from the target onto
a seed layer is not formed over the substrate prior to thethe seed layer to deposit a piezoelectric layer having a
Sputtering.
compression-negative (C) polarity.
2. A method of fabricating a piezoelectric material as
A method as of fabricating a BAW resonator as claimed
claimed in claim 1, wherein the piezoelectric film comprises in 12.
claim 11, further comprising forming a second electrode5
a compression-negative (C) polarity.
3. A method of fabricating a piezoelectric material as over the piezoelectric material.
A method as of fabricating a BAW resonator as claimed
claimed in claim 1, wherein the flowing of hydrogen is con in 13.
claim 11, wherein the seed layer comprises aluminum.
tinuous during the fabricating of the piezoelectric film.
14. A method of fabricating a BAW resonator as claimed in
4. A method of fabricating a piezoelectric material as
claim
13, wherein the first electrode and the second electrode10
claimed in claim 1, further comprising, after the depositing:comprise one of molybdenum (Mo), aluminum (Al), tungsten
ceasing flow of the hydrogen;platinum (Pt), and ruthenium (Ru).
forming a second substrate over the piezoelectric film; and (W),
15. A method of fabricating a BAW resonator as claimed in
Sputtering the piezoelectric material from the target over claim
11, further comprising, after the forming of the firstthe second substrate.
5. A method of fabricating a piezoelectric material as 15 electrode and before the forming of the seed layer, forming aand removing a contaminant from a surface of the firstclaimed in claim 4, further comprising, before forming the plasma
electrode.
Second substrate flowing hydrogen over the second substrate,
16. A method of fabricating a BAW resonator as claimed inwherein the piezoelectric material comprises a compression claim
11, further comprising, after the forming of the seednegative (C) material.
maintaining a flow of an inert gas over the surface of the
6. A method of fabricating a piezoelectric material as layer,
Seed layer during the depositing of the first component and theclaimed in claim3, wherein the substrates comprise a metal. piezoelectricmaterial.
7. A method of fabricating a piezoelectric material as
17.
A
methodof fabricating a BAW resonator as claimed inclaimed in claim 6, wherein the metal comprises one of: claim 12, further
comprising, after the depositing of themolybdenum (Mo), aluminum (Al), tungsten (W), platinum piezoelectricmaterial:
sputtering a second piezoelectric
25(Pt), and ruthenium (Ru).
over the second electrode, wherein the second piezo
8. A method of fabricating a piezoelectric material as material
electric material comprises a compression-positive (C)claimed in claim 1, wherein the first component comprises polarity.
nitrogen and the second component comprises aluminum.
18. A method of fabricating a BAW resonator as claimed in
9. A method of fabricating a piezoelectric material as
12, wherein the first electrode and the second electrodeclaimed in claim 4, wherein the piezoelectric material sput 30 claim
comprisea metal.
tered on the first substrate comprises a compression-negative
19. A method of fabricating a BAW resonator as claimed in(C) material, and the piezoelectric material sputtered over claim
18, wherein the metal comprises one of molybdenum
the second substrate comprises a compression-positive (C) (Mo), aluminum(Al), tungsten (W), platinum (Pt), and ruthematerial.
35
nium
(Ru).
10. A method of fabricating a piezoelectric material as
20. A method of fabricating a BAW resonator as claimed inclaimed in claim 1, wherein the flowing of hydrogen during claim
11, wherein the first component comprises nitrogen andthe depositing forms NH.
thesecondcomponent comprises aluminum.
11. A method of fabricating a bulk acoustic wave (BAW)
21.
A
methodfabricating a BAW resonator as claimed inresonator having a piezoelectric material consisting essen claim 11, whereinofthe
seed layer is selected to fostergrowth oftially of first and second components, the method comprising: 40 thepiezoelectricmaterial
comprising the compression-nega
forming a first electrode over a substrate;
forming a seed layer consisting essentially of the second tive (C) polarity.
22. A method of fabricating a BAW resonator as claimed incomponent over the substrate;
flowing the first component of the piezoelectric material to claim 11, wherein vacuum is maintained during the method.
form the piezoelectric material over a surface of a target 45 23. The method of claim 11, wherein the first component is
consisting essentially of the second component of the nitrogen (N) and the second component is aluminum (Al).
ck
ck
ck
ck
ck
piezoelectric material; and