The scalloping of oxide-nitride-oxide (ONO) stacked layers on vertical sidewalls during high-aspect-ratio contact etch is commonly seen and characterized by the horizontal etching of oxide and nitride layers at different etch rates. To understand the mechanisms of ONO scalloping in complex plasma chemistry, it is crucial to examine the surface chemistry of silicon dioxide and silicon nitride processed with single fluorocarbon (FC) or hydrofluorocarbon (HFC) gases. To simulate the isotropic etching of SiO2 and Si3N4 sidewalls, we use a horizontal trench structure to study the effect of neutral radicals produced by FC (Ar/C4F8), HFC (Ar/CH3F, CH2F2, or CH3F), FC/HFC (Ar/C4F8/CH2F2), or FC/H2 (Ar/C4F8/H2), plasma for aspect-ratio (AR) up to 25. To eliminate the effect of ions, oxide and nitride trench structures were treated by inductively coupled plasma. The changes in the film thickness as a function of AR were probed by ellipsometry. Additionally, x-ray photoelectron spectroscopy (XPS) measurements on oxide and nitride substrates processed by Ar/C4F8 and Ar/CH2F2 plasma were performed at various locations: outside of the trench structure, near the trench entrance (AR = 4.3), and deeper in the trench (AR = 12.9). We find a variety of responses of the trench sidewalls including both FC deposition and spontaneous etching which reflect (1) the nature of the FC and HFC gases, (2) the nature of the surfaces being exposed, and (3) the position relative to the trench entrance. Overall, both the etching and deposition patterns varied systematically depending on the precursor gas. We found that the ONO scalloping at different ARs is plasma chemistry dependent. Oxide showed a binary sidewall profile, with either all deposition inside of the trench (with FC and FC/H2 processing) or etching (HFC and FC/HFC). Both profiles showed a steady attenuation of either the deposition or etching at higher AR. On the nitride substrate, etching was observed near the entrance for HFC precursors, and maximum net etching occurred at higher AR for high F:C ratio HFC precursors like CHF3. XPS measurements performed with Ar/C4F8 and Ar/CH2F2 treated surfaces showed that Ar/C4F8 overall deposited a fluorine-rich film outside and inside of the trench, while Ar/CH2F2 mostly deposited a cross-linked film (except near the trench entrance) with an especially thin graphitic-like film deep inside the trench.

2.
J.
Jang
et al, in
2009 Symposium on VLSI Technology, Digest of Technical Papers
,
Honolulu, HI
,
16–18 June 2009
(
IEEE
, New York,
2009
), pp.
192
193
.
3.
K.
Ishikawa
,
K.
Karahashi
,
T.
Ishijima
,
S. I.
Cho
,
S.
Elliott
,
D.
Hausmann
,
D.
Mocuta
,
A.
Wilson
, and
K.
Kinoshita
,
Jpn. J. Appl. Phys.
57
,
06JA01
(
2018
).
4.
T.
Pekny
et al, “
A 1-Tb density 4b/cell 3D-NAND flash on 176-tier technology with 4-independent planes for read using CMOS-under-the-array
,” in
2022 IEEE International Solid-State Circuits Conference (ISSCC)
,
San Francisco, CA, 21 February 2022
(IEEE, New York,
2022
), pp.
1
3
.
5.
W.
Cho
et al, “
A 1-Tb, 4b/cell, 176-stacked-WL 3D-NAND flash memory with improved read latency and a 14.8Gb/mm2 density
,” in
2022 IEEE International Solid- State Circuits Conference (ISSCC)
,
San Francisco, CA, 21 February 2022
(IEEE, New York,
2022
), pp.
134
135
.
6.
M. A.
Lieberman
and
A. J.
Lichtenberg
,
Principles of Plasma Discharges and Materials Processing
,
2nd ed.
(
Wiley Interscience
,
Hoboken
,
NJ
,
2005
).
7.
S.
Huang
,
C.
Huard
,
S.
Shim
,
S. K.
Nam
,
I.-C.
Song
,
S.
Lu
, and
M. J.
Kushner
,
J. Vac. Sci. Technol. A
37
,
031304
(
2019
).
8.
S.-N.
Hsiao
,
K.
Ishikawa
,
T.
Hayashi
,
J.
Ni
,
T.
Tsutsumi
,
M.
Sekine
, and
M.
Hori
,
Appl. Surf. Sci.
541
,
148439
(
2021
).
9.
M.
Saito
,
H.
Eto
,
N.
Makino
,
K.
Omiya
,
T.
Homma
, and
T.
Nagatomo
,
Jpn. J. Appl. Phys.
40
,
5271
(
2001
).
10.
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
).
11.
V.
Ah-Leung
,
O.
Pollet
,
N.
Possémé
,
M. G.
Barros
,
N.
Rochat
,
C.
Guedj
,
G.
Audoit
, and
S.
Barnola
,
J. Vac. Sci. Technol. A
35
,
021408
(
2017
).
12.
N.
Kuboi
,
T.
Tatsumi
,
H.
Minari
,
M.
Fukasawa
,
Y.
Zaizen
,
J.
Komachi
, and
T.
Kawamura
,
J. Vac. Sci. Technol. A
35
,
061306
(
2017
).
13.
T.
Ito
,
K.
Karahashi
,
M.
Fukasawa
,
T.
Tatsumi
, and
S.
Hamaguchi
,
J. Vac. Sci. Technol. A
29
,
050601
(
2011
).
14.
K.-Y.
Lin
,
C.
Li
,
S.
Engelmann
,
R. L.
Bruce
,
E. A.
Joseph
,
D.
Metzler
, and
G. S.
Oehrlein
,
J. Vac. Sci. Technol. A
36
,
040601
(
2018
).
15.
R. J.
Gasvoda
,
Z.
Zhang
,
S.
Wang
,
E. A.
Hudson
, and
S.
Agarwal
,
J. Vac. Sci. Technol. A
38
,
050803
(
2020
).
16.
H.
Miyazoe
et al,
J. Vac. Sci. Technol. B
36
,
032201
(
2018
).
17.
S. U.
Engelmann
et al,
J. Vac. Sci. Technol. B
35
,
051803
(
2017
).
18.
N.
Marchack
et al,
J. Vac. Sci. Technol. B
36
,
031801
(
2018
).
19.
M.
Schaepkens
,
T. E. F. M.
Standaert
,
N. R.
Rueger
,
P. G. M.
Sebel
,
G. S.
Oehrlein
, and
J. M.
Cook
,
J. Vac. Sci. Technol. A
17
,
26
(
1999
).
20.
M.
Izawa
,
N.
Negishi
,
K.
Yokogawa
, and
Y.
Momonoi
,
Jpn. J. Appl. Phys.
46
,
7870
(
2007
).
21.
L.
Zheng
,
L.
Ling
,
X.
Hua
,
G. S.
Oehrlein
, and
E. A.
Hudson
,
J. Vac. Sci. Technol. A
23
,
634
(
2005
).
22.
L.
Ling
,
X.
Hua
,
L.
Zheng
,
G. S.
Oehrlein
,
E. A.
Hudson
, and
P.
Jiang
,
J. Vac. Sci. Technol. B
26
,
11
(
2008
).
23.
A. J.
Knoll
,
A.
Pranda
,
H.
Lee
, and
G. S.
Oehrlein
,
J. Vac. Sci. Technol. B
37
,
031802
(
2019
).
24.
N.
Hiwasa
,
J.
Kataoka
,
N.
Sasao
,
S.
Kuboi
,
D.
Iino
,
K.
Kurihara
, and
H.
Fukumizu
,
Appl. Phys. Express
15
,
106002
(
2022
).
25.
D.
Metzler
,
R. L.
Bruce
,
S.
Engelmann
,
E. A.
Joseph
, and
G. S.
Oehrlein
,
J. Vac. Sci. Technol. A
32
,
020603
(
2014
).
26.
X. F.
Hua
,
X.
Wang
,
D.
Fuentevilla
,
G. S.
Oehrlein
,
F. G.
Celii
, and
K. H. R.
Kirmse
,
J. Vac. Sci. Technol. A
21
,
1708
(
2003
).
27.
T. E. F. M.
Standaert
,
P. J.
Matsuo
,
S. D.
Allen
,
G. S.
Oehrlein
, and
T. J.
Dalton
,
J. Vac. Sci. Technol. A
17
,
741
(
1999
).
28.
N.
Fairley
et al,
Appl. Surf. Sci. Adv.
5
,
100112
(
2021
).
29.
P.
Kirsch
,
Modern Fluoroorganic Chemistry
(
Wiley
,
Weinheim
,
2004
), p.
15
.
30.
A.
Pranda
,
C.
Li
,
Y.
Seo
, and
G. S.
Oehrlein
,
J. Vac. Sci. Technol. A
39
,
043001
(
2021
).
31.
K.
Takahashi
,
M.
Hori
, and
T.
Goto
,
J. Vac. Sci. Technol. A
14
,
2011
(
1996
).
32.
See the supplementary material online for Fig. S1 which shows the thickness change and XPS spectra of the 175 nm nitride substrate after Ar/C4F8 and Ar/CH2F2 processing.

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