Abstract

In this study, atmospheric-pressure (AP) plasma generated using He/O2/CF4 mixture as feed gas was used to etch the single-crystal silicon (100) wafer and the characteristics of the etched surface were investigated. The wafer morphology and surface elemental composition were analyzed using scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The XPS results reveal that the fluorine element will be deposited on the wafer surface during the etching process when oxygen was not introduced as the feed gas. By detecting the energy and intensity of emitted particles, optical emission spectroscopy (OES) is used to identify the radicals in plasma. The fluorocarbon radicals generated during CF4 plasma ionization can form carbon fluoride polymer, which is considered as one factor to suppress the etching process. The roughness was measured to be changed with the increase in the etching time. The surface appears to be rougher at first when the plasma etching occurred on the subsurface damaged (SSD) layer, and the subsurface cracks would show on the surface after a short-time etching. After the damaged layer was fully removed, etching resulted in the formation of square-opening etching pits. During extended etching, the individual etching pits grew up and coalesced with one another; this coalescence provided an improved surface roughness. This study explains the AP plasma etching mechanism, and the formation of anisotropic surface etching pits at a microscale level for promoting the micromachining process.

References

1.
Maluf
,
N.
,
2002
, “
An Introduction to Microelectromechanical Systems Engineering
,”
Meas. Sci. Technol.
,
13
(
2
), p.
229
.10.1088/0957-0233/13/2/701
2.
Ono
,
K.
,
Nakazaki
,
N.
,
Tsuda
,
H.
,
Takao
,
Y.
, and
Eriguchi
,
K.
,
2017
, “
Surface Morphology Evolution During Plasma Etching of Silicon: Roughening, Smoothing and Ripple Formation
,”
J. Phys. D
,
50
(
41
), p.
414001
.10.1088/1361-6463/aa8523
3.
Marks
,
M. R.
,
Hassan
,
Z.
, and
Cheong
,
K. Y.
,
2015
, “
Ultrathin Wafer Pre-Assembly and Assembly Process Technologies: A Review
,”
Crit. Rev. Solid State
,
40
(
5
), pp.
251
290
.10.1080/10408436.2014.992585
4.
Pei
,
Z. J.
,
Fisher
,
G. R.
, and
Liu
,
J.
,
2008
, “
Grinding of Silicon Wafers: A Review From Historical Perspectives
,”
Int. J. Mach. Tool Manuf.
,
48
(
12–13
), pp.
1297
1307
.10.1016/j.ijmachtools.2008.05.009
5.
Liu
,
T.
,
Ge
,
P.
,
Bi
,
W.
, and
Gao
,
Y.
,
2017
, “
Subsurface Crack Damage in Silicon Wafers Induced by Resin Bonded Diamond Wire Sawing
,”
Mater. Sci. Semicond. Process.
,
57
, pp.
147
56
.10.1016/j.mssp.2016.10.021
6.
Azar
,
A. S.
,
Holme
,
B.
, and
Nielsen
,
Ø.
,
2016
, “
Effect of Sawing Induced Micro-Crack Orientations on Fracture Properties of Silicon Wafers
,”
Eng. Fract. Mech.
,
154
, pp.
262
271
.10.1016/j.engfracmech.2016.01.014
7.
Reiche
,
M.
, and
Wagner
,
G.
,
2003
, “
Wafer Thinning Techniques for Ultra-Thin Wafers
,”
Adv. Packag.
,
12
(
3
), pp.
29
30
.https://sst.semiconductor-digest.com/2003/03/wafer-thinning-techniques-for-ultra-thin-wafers/
8.
Mauer
,
L.
,
Taddei
,
J.
, and
Youssef
,
R.
,
2009
, “
The Role of Wet Etching in Silicon Wafer Thinning
,” SSEC Technical Report.
9.
Siniaguine
,
O.
,
1998
, “
Atmospheric Downstream Plasma Etching of Si Wafers
,”
IEEE/CPMT International Manufacturing Technology Symposium
,
Austin, TX
, Oct. 21, pp.
139
145
.
10.
Hendrix
,
M.
,
Drews
,
S.
, and
Hurd
,
T.
,
2000
, “
Advantages of Wet Chemical Spin-Processing for Wafer Thinning and Packaging Applications
,”
IEEE/CPMT International Electronics Manufacturing Technology Symposium
, Santa Clara, CA, Oct. 3, pp.
229
236
.10.1109/IEMT.2000.910733
11.
Disco Corporation
, 2018, “Stress Relief (Dry polishing),” accessed Aug. 9, 2018, http://www.disco.co.jp/eg/solution/library/strelief.html
12.
Deng
,
H.
,
Takiguchi
,
T.
,
Ueda
,
M.
,
Hattori
,
A. N.
,
Zettsu
,
N.
, and
Yamamura
,
K.
,
2011
, “
Damage-Free Dry Polishing of 4H-SiC Combined With Atmospheric-Pressure Water Vapor Plasma Oxidation
,”
Jpn. J. Appl. Phys.
,
50
(
8S1
), p.
08JG05
.10.7567/JJAP.50.08JG05
13.
Deng
,
H.
,
Ueda
,
M.
, and
Yamamura
,
K.
,
2014
, “
Characterization of 4H-SiC (0001) Surface Processed by Plasma-Assisted Polishing
,”
Int. J. Adv. Manuf. Technol.
,
72
(
1–4
), pp.
1
7
.10.1007/s00170-012-4430-7
14.
Wang
,
R.
,
Zhang
,
C.
,
Liu
,
X.
,
Xie
,
Q.
,
Yan
,
P.
, and
Shao
,
T.
,
2015
, “
Microsecond Pulse Driven Ar/CF4 Plasma Jet for Polymethylmethacrylate Surface Modification at Atmospheric Pressure
,”
Appl. Surf. Sci.
,
328
, pp.
509
515
.10.1016/j.apsusc.2014.12.076
15.
Kawata
,
H.
,
Takao
,
Y.
,
Murata
,
K.
, and
Nagami
,
K.
,
1988
, “
Optical Emission Spectroscopy of CF4+ O2 Plasmas Using a New Technique
,”
Plasma Chem. Plasma Process
,
8
(
2
), pp.
189
206
.10.1007/BF01016157
16.
Park
,
J. S.
,
Seo
,
D. S.
,
Kim
,
H. W.
, and
Hong
,
S. J.
,
2009
, “
Statistical Analysis of the Emission Intensity for Silicon-Dioxide Etching Using Optical Emission Spectroscopy Data
,”
J. Korean Phys. Soc.
,
55
(
5
), pp.
1873
1876
.10.3938/jkps.55.1873
17.
Anand
,
M.
,
Cohen
,
R. E.
, and
Baddour
,
R. F.
,
1981
, “
Surface Modification of Low Density Polyethylene in a Fluorine Gas Plasma
,”
Polymer
,
22
(
3
), pp.
361
371
.10.1016/0032-3861(81)90048-3
18.
Beenakker
,
C. I. M.
,
Van Dommelen
,
J. H. J.
, and
Van De Poll
,
R. P. J.
,
1981
, “
Decomposition and Product Formation in CF4‐O2 Plasma Etching Silicon in the Afterglow
,”
J. Appl. Phys.
,
52
(
1
), pp.
480
485
.10.1063/1.329812
19.
Frühauf
,
J.
,
Gärtner
,
E.
, and
Krönert
,
S.
,
2005
,
Shape and Functional Elements of the Bulk Silicon Microtechnique
,
Springer-Verlag
,
Berlin
.
20.
Bassous
,
E.
,
1978
, “
Fabrication of Novel Three-Dimensional Microstructures by the Anisotropic Etching of (100) and (110) Silicon
,”
IEEE Trans. Electron Devices
,
25
(
10
), pp.
1178
1185
.10.1109/T-ED.1978.19249
21.
Cheng
,
K.
, and
Huo
,
D.
,
2013
,
Micro-Cutting Fundamentals and Applications
,
Wiley
,
New York
.
22.
Shikida
,
M.
,
Tokoro
,
K.
,
Uchikawa
,
D.
, and
Sato
,
K.
,
2000
, “
Surface Morphology of Anisotropically Etched Single-Crystal Silicon
,”
J. Micromech. Microeng.
,
10
(
4
), pp.
522
527
.10.1088/0960-1317/10/4/306
23.
Debnath
,
K.
,
Arimoto
,
H.
,
Husain
,
M. K.
,
Prasmusinto
,
A.
,
Al-Attili
,
A.
,
Petra
,
R.
,
Chong
,
H. M.
,
Reed
,
G. T.
, and
Saito
,
S.
,
2016
, “
Low-Loss Silicon Waveguides and Grating Couplers Fabricated Using Anisotropic Wet Etching Technique
,”
Front. Mater.
,
3
, p.
10
.10.3389/fmats.2016.00010
You do not currently have access to this content.