In this study, a cyclic isotropic plasma atomic layer etching (ALE) process was developed for aluminum oxide that involves fluorination with NF3 plasma and ligand exchange with trimethylaluminum (TMA). The isotropic plasma ALE consists of two steps: fluorination and removal. During the fluorination step, the Al2O3 surface was fluorinated to AlOFx with NF3 plasma at 100 °C. The formation of the AlOFx layer was confirmed by x-ray photoelectron spectroscopy analysis, and the atomic fraction of fluorine on the surface was saturated at 25% after 50 s of plasma fluorination. The depths of the fluorinated layers were in the range of 0.79–1.14 nm at different plasma powers. In the removal step, the fluorinated layer was removed by a ligand exchange reaction with TMA at an elevated temperature range of 250–480 °C. The etch per cycle (EPC) was 0.20–0.30 nm/cycle and saturated after 30 s in the temperature range of 290–330 °C. No etching was observed below 250 °C, and the EPC increased in the temperature range of 250–300 °C during the removal step with the ligand exchange reaction and reached the maximum at 300 °C. Then, the EPC was significantly reduced at high temperatures, possibly due to TMA decomposition. The fluorine atomic fraction on the surface was reduced to 14% after the removal. In conclusion, Al2O3 was successfully etched at the atomic scale by the cyclic plasma ALE process. The average surface roughness of Al2O3 was reduced from 8.6 to 5.3 Å after 20 cycles of etching.

1.
Y.-T.
Oh
,
K.-B.
Kim
,
S.-H.
Shin
,
H.
Sim
,
N.
Van Toan
,
T.
Ono
, and
Y.-H.
Song
,
Microelectron. Eng.
79
,
1
(
2018
).
2.
J. U.
Knickerbocker
 et al, 2008 58th Electronic Components and Technology Conference, Lake Buena Vista, FL, 27–30 May 2008 (2008).
3.
S.
Ye
,
K.
Yamabe
, and
T.
Endoh
,
Mater. Sci. Semicond. Process.
134
,
106046
(
2021
).
4.
A.
Fischer
,
A.
Routzahn
,
S. M.
George
, and
T.
Lill
,
J. Vac. Sci. Technol. A
39
,
030801
(
2021
).
5.
M.
Hirose
,
M.
Koh
,
W.
Mizubayashi
,
H.
Murakami
,
K.
Shibahara
, and
S.
Miyazaki
,
Semicond. Sci. Technol.
15
,
485
(
2000
).
6.
D.
Rathee
,
M.
Kumar
, and
S. K.
Arya
,
Int. J. Comput. Appl.
8
,
10
(
2010
).
7.
R.
Chau
,
S.
Datta
,
M.
Doczy
,
J.
Kavalieros
, and
M.
Metz
, Extended Abstracts of International Workshop on Gate Insulator (IEEE Cat. No. 03EX765), Tokyo, Japan, 6–7 November 2003 (2003).
8.
S.
Saha
,
J. Vac. Sci. Technol. B
19
,
2240
(
2001
).
9.
Q.
Chen
and
J. D.
Meindl
,
Nanotechnology
15
,
S549
(
2004
).
10.
J. A.
Kittl
 et al,
Microelectron. Eng.
86
,
1789
(
2009
).
11.
C.
Zhao
,
C.
Zhao
,
S.
Taylor
, and
P.
Chalker
,
Materials
7
,
5117
(
2014
).
12.
K.
Takahashi
,
K.
Ono
, and
Y.
Setsuhara
,
J. Vac. Sci. Technol. A
23
,
1691
(
2005
).
13.
K.
Yim
,
Y.
Yong
,
J.
Lee
,
K.
Lee
,
H.-H.
Nahm
,
J.
Yoo
,
C.
Lee
,
C.
Seong Hwang
, and
S.
Han
,
NPG Asia Mater.
7
,
e190
(
2015
).
14.
X.
Yang
,
J.-C.
Woo
,
D.-S.
Um
, and
C.-I.
Kim
,
Trans. Electr. Electron. Mater.
11
,
202
(
2010
).
15.
W.
Ban
,
S.
Kwon
,
J.
Nam
,
J.
Yang
,
S.
Jang
, and
D.
Jung
,
Thin Solid Films
641
,
47
(
2017
).
16.
D.-P.
Kim
,
J.-W.
Yeo
, and
C.-I.
Kim
,
Thin Solid Films
459
,
122
(
2004
).
17.
J.
Paul
 et al,
Microelectron. Eng.
86
,
949
(
2009
).
18.
D. W.
Kim
,
C. H.
Jeong
,
K. N.
Kim
,
H. Y.
Lee
,
H. S.
Kim
,
Y. J.
Sung
, and
G. Y.
Yeom
,
Thin Solid Films
435
,
242
(
2003
).
19.
K. S.
Min
,
S. H.
Kang
,
J. K.
Kim
,
Y. I.
Jhon
,
M. S.
Jhon
, and
G. Y.
Yeom
,
Microelectron. Eng.
110
,
457
(
2013
).
20.
A.
Fischer
,
A.
Routzahn
, and
T.
Lill
, ECS Meeting Abstracts MA2020-02 (2020).
21.
Y.
Lee
,
J. W.
DuMont
, and
S. M.
George
,
Chem. Mater.
28
,
2994
(
2016
).
22.
N. J.
Chittock
,
M. F. J.
Vos
,
T.
Faraz
,
W. M. M.
Kessels
,
H. C. M.
Knoops
, and
A. J. M.
Mackus
,
Appl. Phys. Lett.
117
,
162107
(
2020
).
23.
N.
Miyoshi
,
H.
Kobayashi
,
K.
Shinoda
,
M.
Kurihara
,
T.
Watanabe
,
Y.
Kouzuma
,
K.
Yokogawa
,
S.
Sakai
, and
M.
Izawa
,
Jpn. J. Appl. Phys.
56
,
06HB01
(
2017
).
24.
W.
Lu
,
Y.
Lee
,
J. C.
Gertsch
,
J. A.
Murdzek
,
A. S.
Cavanagh
,
L.
Kong
,
J. A.
Del Alamo
, and
S. M.
George
,
Nano Lett.
19
,
5159
(
2019
).
25.
V.
Sharma
,
S. D.
Elliott
,
T.
Blomberg
,
S.
Haukka
,
M. E.
Givens
,
M.
Tuominen
, and
M.
Ritala
,
Chem. Mater.
33
,
2883
(
2021
).
26.
S. M.
George
,
Acc. Chem. Res.
53
,
1151
(
2020
).
27.
J. W.
DuMont
and
S. M.
George
,
J. Chem. Phys.
146
,
052819
(
2017
).
28.
Y.
Kim
,
S.
Lee
,
Y.
Cho
,
S.
Kim
, and
H.
Chae
,
J. Vac. Sci. Technol. A
38
,
022606
(
2020
).
29.
Y.
Cho
,
Y.
Kim
,
S.
Kim
, and
H.
Chae
,
J. Vac. Sci. Technol. A
38
,
022604
(
2020
).
30.
J. C.
Gertsch
,
A. M.
Cano
,
V. M.
Bright
, and
S. M.
George
,
Chem. Mater.
31
,
3624
(
2019
).
31.
C.
Fang
,
Y.
Cao
,
D.
Wu
, and
A.
Li
,
Prog. Nat. Sci. Mater. Int.
28
,
667
(
2018
).
32.
J. W.
Clancey
,
A. S.
Cavanagh
,
J. E. T.
Smith
,
S.
Sharma
, and
S. M.
George
,
J. Phys. Chem. C
124
,
287
(
2020
).
33.
J. A.
Murdzek
,
A.
Rajashekhar
,
R. S.
Makala
, and
S. M.
George
,
J. Vac. Sci. Technol. A
39
,
042602
(
2021
).
34.
A. M.
Cano
,
A. E.
Marquardt
,
J. W.
DuMont
, and
S. M.
George
,
J. Phys. Chem. C
123
,
10346
(
2019
).
35.
S. M.
George
and
Y.
Lee
,
ACS Nano
10
,
4889
(
2016
).
36.
A.
Fischer
,
R.
Janek
,
J.
Boniface
,
T.
Lill
,
K.
Kanarik
,
Y.
Pan
,
V.
Vahedi
, and
R. A.
Gottscho
,
Proc. SPIE
10149, 101490H (2017).
37.
Z.
Wang
,
C.
Carrière
,
A.
Seyeux
,
S.
Zanna
,
D.
Mercier
, and
P.
Marcus
,
J. Electrochem. Soc.
168
,
041503
(
2021
).
38.
Y.-F.
Wang
,
L.-C.
Wang
,
M.
Shih
, and
C.-H.
Tsai
,
Chemosphere
57
,
1157
(
2004
).
39.
G.
Bruno
,
P.
Capezzuto
,
G.
Cicala
, and
P.
Manodoro
,
J. Vac. Sci. Technol. A
12
,
690
(
1994
).
40.
Y.
Huang
 et al,
Sol. Energy Mater. Sol. Cells
208
,
110389
(
2020
).
41.
S. W.
King
,
R. F.
Davis
, and
R. J.
Nemanich
,
J. Vac. Sci. Technol. A
32
,
051402
(
2014
).
42.
R.
Ramos
,
G.
Cunge
,
B.
Pelissier
, and
O.
Joubert
,
Plasma Sources Sci. Technol.
16
,
711
(
2007
).
43.
C. S.
Lai
,
K. M.
Fan
,
H. K.
Peng
,
S. J.
Lin
,
C. Y.
Lee
, and
C. F.
Ai
,
Appl. Phys. Lett.
90
,
172904
(
2007
).
44.
Y.
Lee
,
C.
Huffman
, and
S. M.
George
,
Chem. Mater.
28
,
7657
(
2016
).
45.
J.
Hennessy
,
C. S.
Moore
,
K.
Balasubramanian
,
A. D.
Jewell
,
K.
France
, and
S.
Nikzad
,
J. Vac. Sci. Technol. A
35
,
041512
(
2017
).
46.
D. R.
Zywotko
,
J.
Faguet
, and
S. M.
George
,
J. Vac. Sci. Technol. A
36
,
061508
(
2018
).
47.
S.-K.
Kang
,
J. S.
Oh
,
B. J.
Park
,
S. W.
Kim
,
J. T.
Lim
,
G. Y.
Yeom
,
C. J.
Kang
, and
G. J.
Min
,
Appl. Phys. Lett.
93
,
043126
(
2008
).
48.
J.
Chastain
and
R. C.
King
, Jr.
, Handbook of X-ray photoelectron spectroscopy (
Perkin-Elmer
,
1992
), p.
261
.
49.
Z.
Zhang
,
Y.
Pan
,
J.
Yang
,
Z.
Jiang
, and
H.
Fang
,
J. Cryst. Growth
473
,
6
(
2017
).
50.
K.
Miwa
,
K.
Usami
,
N.
Takada
, and
K.
Sasaki
,
Jpn. J. Appl. Phys.
48
,
126002
(
2009
).
You do not currently have access to this content.