We have investigated the etching of high aspect ratio holes (4μm deep, 0.2μm diameter) in silicon using plasmas maintained in mixtures of SF6, O2, and HBr or Cl2 gases. The etching experiments were conducted in a low pressure (25mTorr), high density, inductively coupled plasma etching reactor with a planar coil. Visualization of the profiles with scanning electron microscopy is used in conjunction with plasma diagnostics such as optical emission and mass spectroscopies to understand the key factors that control the feature profile shape and etch rate. HBr addition to SF6O2 mixture reduces the F-to-O ratio, increases sidewall passivation and reduces mask undercut. Addition of Cl2 to SF6O2 discharge also decreases the F-to-O ratio, but Cl-enhanced F chemical etching of silicon significantly increases the mask undercut and lateral etching. In both SF6O2HBr and SF6O2Cl2 mixtures, reduction of O2 flow rate and subsequent increase of the halogen-to-O ratio eventually results in significant lateral etching because of the lack of oxygen required to form a siliconoxyhalide passivating film on the sidewalls.

1.
A. A.
Ayon
,
R. A.
Braff
,
R.
Bayt
,
H. H.
Sawin
, and
M. A.
Schmidt
,
J. Electrochem. Soc.
146
,
2730
(
1999
).
2.
W. C.
Tian
,
J. W.
Weigold
, and
S. W.
Pang
,
J. Vac. Sci. Technol. B
18
,
1890
(
2000
).
3.
H. F.
Winters
and
J. W.
Coburn
,
Surf. Sci. Rep.
14
,
161
(
1992
).
4.
D. L.
Flamm
,
V. M.
Donnelly
, and
J. A.
Mucha
,
J. Appl. Phys.
52
,
3633
(
1981
).
5.
R.
Dagostino
and
D. L.
Flamm
,
J. Appl. Phys.
52
,
162
(
1981
).
6.
S.
Aachboun
and
P.
Ranson
,
J. Vac. Sci. Technol. A
17
,
2270
(
1999
).
7.
S.
Aachboun
,
P.
Ranson
,
C.
Hilbert
, and
M.
Boufnichel
,
J. Vac. Sci. Technol. A
18
,
1848
(
2000
).
8.
M. A.
Blauw
,
T.
Zijlstra
,
R. A.
Bakker
, and
E.
van der Drift
,
J. Vac. Sci. Technol. B
18
,
3453
(
2000
).
9.
M.
Boufnichel
,
S.
Aachboun
,
F.
Grangeon
,
P.
Lefaucheux
, and
P.
Ranson
,
J. Vac. Sci. Technol. B
20
,
1508
(
2002
).
10.
M.
Boufnichel
,
S.
Aachboun
,
P.
Lefaucheux
, and
P.
Ranson
,
J. Vac. Sci. Technol. B
21
,
267
(
2003
).
11.
G.
Craciun
,
M. A.
Blauw
,
E.
van der Drift
,
P. M.
Sarro
, and
P. J.
French
,
J. Micromech. Microeng.
12
,
390
(
2002
).
12.
C. P.
Demic
,
K. K.
Chan
, and
J.
Blum
,
J. Vac. Sci. Technol. B
10
,
1105
(
1992
).
13.
R.
Dussart
,
M.
Boufnichel
,
G.
Marcos
,
P.
Lefaucheux
,
A.
Basillais
,
R.
Benoit
,
T.
Tillocher
,
X.
Mellhaoui
,
H.
Estrade-Szwarckopf
, and
P.
Ranson
,
J. Micromech. Microeng.
14
,
190
(
2004
).
14.
S.
Gomez
,
R. J.
Belen
,
M.
Kiehlbauch
, and
E. S.
Aydil
,
J. Vac. Sci. Technol. A
22
,
606
(
2004
).
15.
T.
Syau
,
B. J.
Baliga
, and
R. W.
Hamaker
,
J. Electrochem. Soc.
138
,
3076
(
1991
).
16.
J. W.
Coburn
,
J. Vac. Sci. Technol. A
12
,
617
(
1994
).
17.
K. M.
Chang
,
T. H.
Yeh
,
I. C.
Deng
, and
H. C.
Lin
,
J. Appl. Phys.
80
,
3048
(
1996
).
18.
G. Y.
Yeom
,
Y.
Ono
, and
T.
Yamaguchi
,
J. Electrochem. Soc.
139
,
575
(
1992
).
19.
A. P.
Mahorowala
,
H. H.
Sawin
,
R.
Jones
, and
A. H.
Labun
,
J. Vac. Sci. Technol. B
20
,
1055
(
2002
).
20.
D. X.
Ma
,
T. A.
Lin
, and
C. H.
Chen
,
J. Vac. Sci. Technol. A
10
,
1217
(
1992
).
21.
M. A.
Vyvoda
,
M.
Li
,
D. B.
Graves
,
H.
Lee
,
M. V.
Malyshev
,
F. P.
Klemens
,
J. T. C.
Lee
, and
V. M.
Donnelly
,
J. Vac. Sci. Technol. B
18
,
820
(
2000
).
22.
C. K.
Yeon
and
H. J.
You
,
J. Vac. Sci. Technol. A
16
,
1502
(
1998
).
23.
S. J.
Ullal
,
H.
Singh
,
J.
Daugherty
,
V.
Vahedi
, and
E. S.
Aydil
,
J. Vac. Sci. Technol. A
20
,
1195
(
2002
).
24.
S. J.
Ullal
,
H.
Singh
,
V.
Vahedi
, and
E. S.
Aydil
,
J. Vac. Sci. Technol. A
20
,
499
(
2002
).
25.
S. J.
Ullal
,
A. R.
Godfrey
,
E.
Edelberg
,
L.
Braly
,
V.
Vahedi
, and
E. S.
Aydil
,
J. Vac. Sci. Technol. A
20
,
43
(
2002
).
26.
R. A.
Gottscho
and
V. M.
Donnelly
,
J. Appl. Phys.
56
,
245
(
1984
).
27.
V. M.
Donnelly
,
M. V.
Malyshev
,
A.
Kornblit
,
N. A.
Ciampa
,
J. I.
Colonell
, and
J. T. C.
Lee
,
Jpn. J. Appl. Phys., Part 1
37
,
2388
(
1998
).
28.
V. M.
Donnelly
,
J. Vac. Sci. Technol. A
14
,
1076
(
1996
).
29.
J. W.
Coburn
and
M.
Chen
,
J. Appl. Phys.
51
,
3134
(
1980
).
30.
R. E.
Walkup
,
K. L.
Saenger
, and
G. S.
Selwyn
,
J. Chem. Phys.
84
,
2668
(
1986
).
31.
R. J.
Belen
,
S.
Gomez
,
D.
Cooperberg
,
M.
Kiehlbauch
, and
E. S.
Aydil
,
J. Vac. Sci. Technol. A
A23
,
1430
(
2005
).
32.
G. S.
Oehrlein
,
J. F.
Rembetski
, and
E. H.
Payne
,
J. Vac. Sci. Technol. B
8
,
1199
(
1990
).
33.
G. P.
Kota
,
J. W.
Coburn
, and
D. B.
Graves
,
J. Vac. Sci. Technol. A
17
,
282
(
1999
).
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