Chemical dissolution of indium arsenide in the Br₂-HBr solutions
The nature and kinetics of InAs chemical dissolution and chemical cutting, in the bromine solutions in hydrobromic acid have been investigated. It was shown that at low (up to 6 vol.%) bromine concentrations the InAs dissolution rate grows linearly with bromine concentration. Such solutions may be u...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
1999
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| Zitieren: | Chemical dissolution of indium arsenide in the Br₂-HBr solutions / Z.F. Tomashik, S.G. Danylenko, V.N. Tomashik, M.Yu. Kravetski // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 4. — С. 73-75. — Бібліогр.: 10 назв. — англ. |
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irk-123456789-1202552017-06-12T03:04:45Z Chemical dissolution of indium arsenide in the Br₂-HBr solutions Tomashik, Z.F. Danylenko, S.G. Tomashik, V.N. Kravetski, M.Yu. The nature and kinetics of InAs chemical dissolution and chemical cutting, in the bromine solutions in hydrobromic acid have been investigated. It was shown that at low (up to 6 vol.%) bromine concentrations the InAs dissolution rate grows linearly with bromine concentration. Such solutions may be used to chemically polish InAs. Solutions containing from 20 to 30 vol.% Br₂ in HBr dissolve InAs with the rate 25 to 50 µ/min forming polished surfaces with etch pits. Such solutions may be used to chemically cut indium arsenide. 1999 Article Chemical dissolution of indium arsenide in the Br₂-HBr solutions / Z.F. Tomashik, S.G. Danylenko, V.N. Tomashik, M.Yu. Kravetski // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 4. — С. 73-75. — Бібліогр.: 10 назв. — англ. 1560-8034 PACS 81,65 C. http://dspace.nbuv.gov.ua/handle/123456789/120255 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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The nature and kinetics of InAs chemical dissolution and chemical cutting, in the bromine solutions in hydrobromic acid have been investigated. It was shown that at low (up to 6 vol.%) bromine concentrations the InAs dissolution rate grows linearly with bromine concentration. Such solutions may be used to chemically polish InAs. Solutions containing from 20 to 30 vol.% Br₂ in HBr dissolve InAs with the rate 25 to 50 µ/min forming polished surfaces with etch pits. Such solutions may be used to chemically cut indium arsenide. |
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Article |
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Tomashik, Z.F. Danylenko, S.G. Tomashik, V.N. Kravetski, M.Yu. |
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Tomashik, Z.F. Danylenko, S.G. Tomashik, V.N. Kravetski, M.Yu. Chemical dissolution of indium arsenide in the Br₂-HBr solutions Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Tomashik, Z.F. Danylenko, S.G. Tomashik, V.N. Kravetski, M.Yu. |
| author_sort |
Tomashik, Z.F. |
| title |
Chemical dissolution of indium arsenide in the Br₂-HBr solutions |
| title_short |
Chemical dissolution of indium arsenide in the Br₂-HBr solutions |
| title_full |
Chemical dissolution of indium arsenide in the Br₂-HBr solutions |
| title_fullStr |
Chemical dissolution of indium arsenide in the Br₂-HBr solutions |
| title_full_unstemmed |
Chemical dissolution of indium arsenide in the Br₂-HBr solutions |
| title_sort |
chemical dissolution of indium arsenide in the br₂-hbr solutions |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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1999 |
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http://dspace.nbuv.gov.ua/handle/123456789/120255 |
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Chemical dissolution of indium arsenide in the Br₂-HBr solutions / Z.F. Tomashik, S.G. Danylenko, V.N. Tomashik, M.Yu. Kravetski // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 4. — С. 73-75. — Бібліогр.: 10 назв. — англ. |
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Semiconductor Physics Quantum Electronics & Optoelectronics |
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2025-07-08T17:32:57Z |
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2025-07-08T17:32:57Z |
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1837100934722748416 |
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7 3© 1999, Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
Semiconductor Physics, Quantum Electronics & Optoelectronics. 1999. V. 2, N 4. P. 73-75.
1. Introduction
The etchant containing elemental bromine are widely used
to etch III-V semiconductor compounds and solid solutions
based on them. Such compounds are rather easily oxidized
with bromine, yielding products that readily dissolve in a
number of solvents. The great bulk of bromine-containing
etchants belong to the polishing ones. This means that etc-
hing rate for them is determined by diffusion stages of a
heterogeneous chemical reaction.
Bromine solutions in organic solvents are most often
used as bromine-containing etchants. According to [1],
the best results when performing polishing etching of
InSb can be achieved with those etchants where metha-
nol, dimethylsulfoxide, dimethylformamide, ethylene
glycol serve as solvents. During the technological proce-
dures aimed at semiconductor surface preparation the
solutions of bromine in methanol are used rather advan-
tageously [2-6]. It is suggested that indium, arsenic and
antimony pass into solution as methoxybromides, and
the reaction between InAs and Br2 is of the first order in
oxidant in the methanol-tetrachloride of carbon solu-
tion [2]. The rate of InP, InAs and GaAs etching grows
linearly with bromine concentration at bromine content
in methanol up to 6 vol.% [3]. Both the dissolution rate
and sample surface quality after etching highly depend
on Br2 concentration in solution. For InAs the polishing
concentrations of Br2 in CH3OH lie within the 1.5 to
2 vol.% range. Stirring of solution considerably affects
the chemical reaction rate, especially at low Br2 contents
in methanol. In this case InP, InAs and GaAs dissolving in
the bromine-methanol solutions occurs according to mixed
kinetics.
When InSb is treated with a bromine-methanol solu-
tion, then a stoichiometric In/Sb proportion retains in
the surface layers [4]. Etching of InSb in the 0.5 vol.%
Br2 in CH3OH solution leads to formation of a surface
oxide film (up to 3 nm thick). This film is made up of a
mixture of In2O3 and Sb2O5 [5]. Use of 5 vol.% Br2 solu-
tion in methanol for InP treatment enables one to ob-
tain surfaces with the lowest amount of impurities [6].
For local etching of indium phosphide a Br2 solution in
dimethylformamide is recommended [7].
As bromine dissolver, not only organic solvents but
hydrobromic acid may be used. The latter exhibits high
complexing ability and can dissolve in it (and hold for
long) rather big amounts of Br2, contrary to organic sol-
vents (e.g., CH3OH or C2H5OH) that intensively evapo-
rate during the sample cutting, with bromine quickly
volatilizing. Besides, methanol is very toxic, and viscous
ethylene glycol (although being less toxic) is more suit-
able for polishing compositions at low Br2 contents. For
chemical etching and chemical cutting of CdTe, Br2 in
HBr solutions are used; dissolution processes occurring
in this case have been adequately studied [8]. For chemi-
cal cutting of InSb the 20 vol.% Br2 solution in HBr has
been offered [9]; the authors, however, have not given
any information on the kinetics of dissolving. Chemical
dissolution of InAs in the Br2-HBr solutions has not been
studied up to setting the problem by us in this paper.
PACS 81,65 C.
Chemical dissolution of indium arsenide in the
Br2-HBr solutions
Z.F.Tomashik, S.G.Danylenko, V.N.Tomashik, M.Yu.Kravetski
Institute of Semiconductor Physics, NAS of Ukraine,
41, prospekt Nauki, 03028 Kyiv, Ukraine, Tel.: (38044) 2655755
Abstract. The nature and kinetics of InAs chemical dissolution and chemical cutting, in the bromine
solutions in hydrobromic acid have been investigated. It was shown that at low (up to
6 vol.%) bromine concentrations the InAs dissolution rate grows linearly with bromine concentra-
tion. Such solutions may be used to chemically polish InAs. Solutions containing from 20 to
30 vol.% Br2 in HBr dissolve InAs with the rate 25 to 50 µ/min forming polished surfaces with etch
pits. Such solutions may be used to chemically cut indium arsenide.
Key words: dissolution, hydrobromic acid, etchant, indium arsenide, bromine, diffusion stage.
Paper received 01.10.99; revised manuscript received 15.12.99; accepted for publication 17.12.99.
Z.F.Tomashik et al.: Chemical dissolution of indium arsenide in...
74 SQO, 2(4), 1999
2. Results and discussion
The objective of this paper is to investigate processes of
InAs chemical dissolution in the Br2-HBr solutions, as well
as to optimize both compositions and technological proce-
dures used at InAs polishing and chemical cutting in the
above solutions.
The InAs dissolution rate was found using a unit for
chemico-dynamic polishing in which the hydrodynamic ro-
tation of a disc has been realized. This enabled us to meas-
ure the etching rate keeping the thickness of the boundary
diffusion layer constant. Our experiments were performed
for single-crystal undoped n-InAs samples. The wafers
whose areas were about 0.5 cm2 have been cut from ingots
and, after mechanical grinding and polishing, etched in a
polishing solution to remove the layer that has been dis-
rupted at cutting, grinding, and chemico-mechanical polish-
ing. The substrates have been put into a special fluoroplastic
holder. The dissolution rate was determined from the wafer
thickness decrease using a IC-1 clockwork indicator. Three
or four samples were being dissolved at a time.
Chemical cutting was made using an updated machine
for chemical cutting SKhR-2. The essence of chemical
cutting is that a thin layer of water solution of a reagent
is put on the cutting string (wire) surface. This wire is
sliding over the surface of the cut sample, being forced
against it by a preset effort (about 10-2 N). The layer of
the reagent water solution serves as a lubricant. At the
areas where the solution is in contact with the cut sam-
ple surface (i.e., near the wire) the chemical dissolution
of the sample material occurs. The products diffuse from
the sample surface into a gap between it and the wire,
and then are being carried out of the gap. As the surface
is etched off the sample is also transferred towards the
wire. The velocity of this transfer is equal to that of the
surface dissolution (etching off), so the pressure exerted
by the string on the sample during the chemical cutting
process remains the same.
The chemical cutting rate was calculated from the time
needed to cut two or three plates off the same InAs sin-
gle crystal (that has the shape of a parallelepiped). The
Br2 concentration in solutions changed but slightly dur-
ing etching and cutting (about 10-15 min). Chemical etch-
ing was performed at a temperature of 22°C, while chemi-
cal cutting was performed at 15°C, with the aim to stabi-
lize the dissolution rate and prevent the Br2 volatilization.
Shown in Fig.1 are the concentration dependencies of
the etching and chemical cutting rates for indium arsenide.
One can see that (as in the case of InAs dissolving in the
bromine solution in methanol [3]) the dissolution rate grows
linearly with bromine content at Br2 concentrations up to 6-
7 vol.%. At further increase of bromine concentration the
dissolution rate slows down a little. But when the Br2 con-
centration reaches 20 vol.%, then the indium arsenide dis-
solution rate begins to rise steeply. If the solutions are used
that contain over 33 vol.% Br2 in hydrobromic acid, then
the interaction rate becomes too high to be accurately mea-
sured, due to disintegration of the surfaces of dissolving
samples.
At low bromine concentrations the chemical cutting rate
increases much more steeply than in the case of chemical
etching. A possible explanation is that the active solution is
supplied just to a narrow gap where the sample is cut, and
the products of interaction are immediately carried out of
the interaction area. Besides, one should not neglect a me-
chanical interaction between the string and sample that
favors removal of the surface film made of the interaction
products. Further increase of bromine concentration makes
the chemical cutting rate to flatten out at 20-30 vol.% Br2.
Slowing down of the chemical cutting rate at high bromine
concentrations may be explained by high volatility of bro-
mine. This prevents to supply a solution with high Br2 con-
tent to the place where cutting occurs. When such solu-
tions are transported with a string, the bromine concentra-
tion goes down steeply with time. So the optimum solution
to be used for chemical cutting is that where the Br2 content
is 20 vol.%.
As in the case of CdTe chemical etching with Br2 solu-
tions in hydrobromic acid [8], at low bromine concentra-
tions the rate of In etching in such solutions should be
determined by the rate of bromine diffusion to the surface of
dissolved sample. It is low-concentration solutions of bro-
mine that are used to chemically polish semiconductor com-
pounds. To find out in what (diffusion or kinetic) region the
InAs dissolution in the low-concentration Br2-HBr solutions
occur, we have plotted the dissolution rate (v) versus disc
rotation rate (r) curves in the v -1-r -1/2 coordinates [3,10]. If
the process is limited with diffusion, such curves pass
through the origin of the coordinates. An increase in impor-
tance of chemical reaction during the total dissolution proc-
ess results in a decrease of the angle of inclination of the
above curves and, in the limit (when the chemical interac-
tion rate is the rate-determining factor for the total dissolu-
tion process) the straight lines become parallel to the x-axis.
From Fig. 2 one can see that the process of InAs disso-
lution in 1 and 2 vol.% Br2 solutions in HBr is determined by
a mixed kinetics because the straight lines are non-parallel
to the x-axis and there are y-intercepts.
V, m/minµ
100
80
60
40
40
20
20 3010
0
0
c(Br ), vol.% 2
2
1
Fig.1. Concentration dependencies of the InAs chemical etching rate
(1) and chemical cutting (2) in the Br2-HBr solutions.
Z.F.Tomashik et al.: Chemical dissolution of indium arsenide in...
75SQO, 2(4), 1999
Shown in Fig. 3 are the InAs dissolution rate versus
temperature curves for those above solutions where the
effect of angular motion rate on the dissolution rate was
studied. From these curves we have calculated the appar-
ent activation energy values (Ea). It is commonly sup-
posed [10] that those processes in water solutions for
which Ea < 35-40 kJ/mole are controled by the diffusion
rate; at Ea > 40 kJ/mole the process rate is immediately de-
termined by the chemical reaction rate. Our results indicate
that the dissolution process is controled with diffusion, since
the apparent activation energy for InAs dissolution in
1(2) vol.% Br2 solution in HBr is 11.2 (18.0) kJ/mole. Some
nonconsistency between the results obtained when stu-
dying how the InAs dissolution rate depends on the disc
rotation rate (mixed kinetics) and temperature (diffusion limi-
tation of the process) may be attributed either to the fact
that in the case of mixed kinetics the diffusion processes
dominate, or to the fact that the activation energy of chemi-
cal interaction is too low.
Conclusions
It was found that the rate of InAs dissolution in the Br2
solutions in HBr grows linearly with bromine concen-
tration at low (up to 6 vol.%) Br2 content. Such solu-
tions may be used to chemically polish InAs. The best
surfaces are obtained, at 2.0-5.0 vol. % Br2 content in
the solution; the etching rate varies from 5 to 10 µm/min
at 22°C and disc rotation rate r = 52 min-1. The solu-
tions that contain 20-30 vol.% Br2 in HBr dissolve InAs
with the rate of 25-50 µm/min, forming polished sur-
faces with etch pits. The results obtained enabled us to
optimize both solution compositions and technological
conditions used for InAs cutting. These are 20 vol.% Br2
in HBr at 15°C and the tungsten string (80 µm in diam-
eter) velocity of 25 cm/s.
References
1. V.V. Starovoitova, V.A.Sannikov, Study of the process of indium
antimonide etching in the dimethylformamide glycerin-bromine
system (in Russian) // Elektronnaya Tekhnika, Ser. 6. Materialy
No.11, pp.106-109 (1980).
2. S.V.Temerev, Kinetics of indium antimonide and indium arsenide
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system (in Russian) // Zhurn. Fiz. Khim. 63(8), pp.2226-2228
(1989).
3. V.A.Perevoschikov, Processes of chemicodynamic polishing of
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electrons // J.Microsc. et Spectrosc. Electron. 5(2), pp.201-206
(1980).
5. X.Tang, R.G.Van Welzenis, F.M.Van Setten, A.J.Bosh, Oxida-
tion of the InSb surface at room temperature // Semicond. Sci.
and Technol. 1(6), pp.355-365 (1986).
6. P.G.Dvoryankina, V.F.Dvoryankin, N.Ya.Cherevatskii, Effect of
chemical treatment and ion bombardment on the InP {100} sur-
face composition (in Russian) // Poverkhnost’. Fizika, Khimiya,
Mekhanika No.8, pp.108-113 (1989).
7. L.I.Vozmilova, M.M.Berdichenko, Investigation of GaAs and InP
local etching with bromine dimethylformamide solution (in Rus-
sian) // Izv. AN SSSR. Neorgan. Mater. 16(1), pp.13-17 (1980).
8. A.A.Sava, V.N.Tomashik, A.V.Fomin, M.Yu.Kravetski, O.A.Yaku-
btsov, V.K.Puzhevich, V.I.Makhnyuk, Chemical dissolution of
cadmium telluride in the Br2-HBr system solutions (in Russian) //
Izv. AN SSSR. Neorgan. Mater. 25(12), pp.1997-2001 (1989).
9. N.N.Grigor’ev, M.Yu.Kravetski, A.V.Fomin, An approximate
model for process of chemical cutting of thin crystalline wafers (in
Russian) // Optich. Zhurn. N 8, pp.71-72 (1993).
10. B.D.Luft, V.A.Perevoschikov, L.N.Vozmilova et al., Physico-
chemical Techniques for Semiconductor Surface Treatment (in
Russian), Radio i Svyaz’, Moscow, 1982.
V , mµmin/-1
1
2
0.5
0.4
0.3
0.2
0.08 0.10 0.12 0.14 0.16 0.18 0.20
, min 1/2-1/2
Fig.2. Dependence of the rate of InAs dissolution in the 1(1) and
2 vol.% (2) Br2 solutions in HBr on the stirring rate.
Fig.3. Temperature dependence of the rate of InAs dissolution in
1 (1) and 2 vol.% (2) Br2 solutions in HBr.
µm/min]
1
2
0.4
0.8
1.2
1.6
2.0
2.4
ln[V,
0.0026 0.0028 0.0030 0.0032 0.0034 0.0036
1/T, K-1
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