Mass spectroscopy is used to characterize the endpoint uniformity of silicon dioxide etching in an electron cyclotron resonance (ECR) plasma etch process. Etch products are observed using a two stage differentially pumped mass spectrometry system attached to the ECR process chamber. Specifically, using CF4 and D2 etch gases, the partial pressure of CO-containing etch products decays near the endpoint, and the rate of signal decay is directly correlated with the uniformity determined from optical interferometry thickness measurements. To correlate the mass spectrometer signal with the etch rate variation across the wafer, etch uniformity is altered by changing the ECR electromagnet geometry and by modifying the initial oxide uniformity. A COF2 etch product material balance is developed to model the observed concentration versus time data, resulting in a quantitative correlation between change in endpoint slope and uniformity. The ability to utilize a process-state sensor, such as a mass spectrometer, for wafer-state information will result in new approaches for sensing, optimizing, and controlling integrated circuit fabrication processes.

1.
T. E.
Benson
,
L. I.
Kamlet
,
P.
Klimecky
, and
F. L.
Terry
, Jr.
,
J. Electron. Mater.
25
,
955
(
1996
).
2.
D.
Economou
,
E. S.
Aydil
, and
G.
Barna
,
Solid State Technol.
34
,
107
(
1991
).
3.
H. L.
Maynard
,
N.
Layadi
, and
J. T.
Lee
,
J. Vac. Sci. Technol. B
15
,
109
(
1997
).
4.
S.
Vallon
,
O.
Joubert
,
L.
Vallier
,
F.
Ferrieu
,
B.
Drevillon
, and
N.
Blayo
,
J. Vac. Sci. Technol. A
15
,
865
(
1997
).
5.
I.
Tepermeister
,
W. T.
Conner
,
T.
Alzaben
,
H.
Barnard
,
K.
Gehlert
, and
D.
Scipione
,
Solid State Technol.
39
,
63
(
1996
).
6.
J. L.
Cecchi
,
J. E.
Stevens
,
R. L.
Jarecki
, Jr.
, and
Y. C.
Huang
,
J. Vac. Sci. Technol. B
9
,
318
(
1991
).
7.
Z.
Wan
,
J.
Liu
, and
H. H.
Lamb
,
J. Vac. Sci. Technol. A
13
,
2035
(
1995
).
8.
P. K.
Mozumder
and
G. G.
Barna
,
IEEE Trans. Semicond. Manuf.
7
,
1
(
1994
).
9.
S.
Thomas
III
,
H. H.
Chen
,
C. K.
Hanish
,
J. W.
Grizzle
, and
S. W.
Pang
,
J. Vac. Sci. Technol. B
14
,
2531
(
1996
).
10.
K.
Sung
and
S. W.
Pang
,
Jpn. J. Appl. Phys., Part 1
33
,
7112
(
1994
).
11.
M. J.
Buie
,
J. T.
Pender
,
J.
Soniker
,
M. L.
Brake
, and
M.
Elta
,
J. Vac. Sci. Technol. A
13
,
1930
(
1995
).
12.
H. L.
Maynard
,
E. A.
Reitman
,
J. T. C.
Lee
, and
D. E.
Ibbotson
,
J. Electrochem. Soc.
143
,
2029
(
1996
).
13.
P. J. Wolf, Masters thesis, North Carolina State University, 1996.
14.
L. L.
Tedder
,
G. W.
Rubloff
,
I.
Shareef
,
M.
Anderle
,
D. H.
Kim
, and
G. N.
Parsons
,
J. Vac. Sci. Technol. B
13
,
1924
(
1995
).
15.
A. I.
Chowdhury
,
W. W.
Read
,
G. W.
Rubloff
,
L. L.
Tedder
, and
G. N.
Parsons
,
J. Vac. Sci. Technol. B
15
,
127
(
1997
).
16.
P. K. Mozumder and G. G. Barna, Technical Activity Report, Semiconductor Process and Design Center, Texas Instruments, Dallas, TX, August 1991.
17.
J. W.
Coburn
and
H. F.
Winters
,
J. Vac. Sci. Technol.
16
,
391
(
1979
).
18.
M.
Oshima
,
Surf. Sci.
86
,
858
(
1979
).
19.
J. W.
Butterbaugh
,
D. C.
Gray
, and
H. H.
Sawin
,
J. Vac. Sci. Technol. B
9
,
1461
(
1991
).
20.
G. S.
Oehrlein
,
Y.
Zhang
,
D.
Vender
, and
M.
Haverlag
,
J. Vac. Sci. Technol. A
12
,
323
(
1994
).
21.
N. R.
Rueger
,
J. J.
Beulens
,
M.
Schaepkens
,
M. F.
Doemling
,
J. M.
Mirza
,
T. E. F. M.
Standaert
, and
G. S.
Oehrlein
,
J. Vac. Sci. Technol. A
15
,
1881
(
1997
).
This content is only available via PDF.
You do not currently have access to this content.