Chalcogenide materials based on GeSbTe (GST) ternary alloys are patterned using inductively coupled plasma in the manufacturing of phase change memories. The current process challenge is to maintain the GST composition and surface morphology to guarantee the memory performances. In this paper, the authors investigate the etching effects of different halogen plasmas (HBr, CF4, and Cl2) on an optimized Ge-rich GST alloy. Using x-ray photoelectron spectroscopy (XPS) and plasma profiling time-of-flight mass spectrometry as complementary techniques, the authors noticed that the etched GST surface shows a stronger Te-rich damaged layer in the sequence of CF4 > Cl2 > HBr. It is closely related to the higher affinity between halogen and GST elements in the sequence of Ge > Sb > Te. By comparing the etch rates with and without rf bias voltage, HBr etching is shown to be mainly related to the physical ion bombardment. On the contrary, Cl2 plasma is mostly chemical and generates the roughest surface. The presence of a C-F passivation layer with CF4 plasma shows that both chemical reactivity and physical bombardment are necessary to etch efficiently the GST film. The oxidation of the HBr-etched GST surface was monitored by XPS as a function of several air exposure times. As a conclusion, the GST oxidation becomes critical after 24 h of air exposure.

1.
M.
Pasotti
 et al,
43rd Proceedings of the ESSCIRC 2017
, Leuven, Belgium, September 2017 (
IEEE
,
2017
), pp.
320
323
.
2.
M.
Pasotti
 et al,
IEEE J. Solid State Circuits
1
, 1 (
2018
).
3.
G. W.
Burr
 et al,
J. Vac. Sci. Technol. B
28
,
223
(
2010
).
4.
W.-C.
Chien
 et al,
IEEE Trans. Electron Devices.
, November 2018, Vol. 65, No. 11, pp. 5172–5179.
5.
H. Y.
Cheng
 et al,
Proceedings of the IEDM
, Washington, DC, December 2011 (IEEE
2011
), pp.
3.4.1
3.4.4
.
6.
S.-K.
Kang
,
M.-H.
Jeon
,
J.-Y.
Park
,
M. S.
Jhon
, and
G.-Y.
Yeom
,
Jpn. J. Appl. Phys.
50
,
086501
(
2011
).
7.
S.-K.
Kang
,
M. H.
Jeon
,
J. Y.
Park
,
G. Y.
Yeom
,
M. S.
Jhon
,
B. W.
Koo
, and
Y. W.
Kim
,
J. Electrochem. Soc.
158
,
H768
(
2011
).
8.
J.
Li
 et al,
Appl. Surf. Sci.
378
,
163
(
2016
).
9.
Y.
Song
,
R.
Huang
,
Y.
Zhang
, and
H.
Zhang
,
Proceedings of the CSTIC
, Shanghai, China, March 2016 (
IEEE
,
2016
), pp.
1
3
.
10.
L.
Shen
 et al,
Appl. Phys. A
122
, 1 (
2016
).
11.
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
).
12.
L. V.
Yashina
,
R.
Püttner
,
V. S.
Neudachina
,
T. S.
Zyubina
,
V. I.
Shtanov
, and
M. V.
Poygin
,
J. Appl. Phys.
103
,
094909
(
2008
).
13.
E.
Gourvest
,
B.
Pelissier
,
C.
Vallée
,
A.
Roule
,
S.
Lhostis
, and
S.
Maitrejean
,
J. Electrochem. Soc.
159
,
H373
(
2012
).
14.
A.
Tempez
,
S.
Legendre
,
J.-P.
Barnes
, and
E.
Nolot
,
J. Vac. Sci. Technol. B
34
,
03H120
(
2016
).
15.
F. L.
King
,
J.
Teng
, and
R. E.
Steiner
,
J. Mass. Spectrom.
30
,
1061
(
1995
).
16.
S. W.
Schmitt
,
C.
Venzago
,
B.
Hoffmann
,
V.
Sivakov
,
T.
Hofmann
,
J.
Michler
,
S.
Christiansen
, and
G.
Gamez
,
Prog. Photovoltaics Res. Appl.
22
,
371
(
2014
).
17.
QUASES software, see: http://www.quases.com/products/quases-imfp-tpp2m/ using the TTP-2M formula from
S.
Tanuma
,
C. J.
Powell
, and
D. R.
Penn
,
Surf. Interface Anal.
20
,
77
(
1993
).
18.
D. R.
Lide
,
CRC Handbook of Chemistry and Physics
(
CRC
,
Boca Raton
,
1995
).
19.
M.
Aspiala
,
D.
Sukhomlinov
, and
P.
Taskinen
,
Solid State Ion.
265
,
80
(
2013
).
20.
B.
Onsia
 et al,
Solid State Phenom.
103–104
,
19
(
2005
).
21.
V.
Sousa
 et al,
VLSI Technology
(
IEEE
,
2015
), pp.
T98
T99
.
22.
P.
Noé
,
C.
Vallée
,
F.
Hippert
,
F.
Fillot
, and
J.-Y.
Raty
,
Semicond. Sci. Tech.
33
,
013002
(
2018
).
You do not currently have access to this content.