Dissolution of indium arsenide in nitric solutions of the hydrobromic acid
Dissolution of InAs in HNO₃-HBr-H₂O solutions is studied. The surface of equal etching rates is constructed, and the limiting stages of the dissolution process are determined. Depending on the [HNO₃]/[HBr] ratio, InAs dissolution may be limited by kinetic, or diffusion, or combined mechanisms. The d...
Gespeichert in:
| Datum: | 1999 |
|---|---|
| Hauptverfasser: | , , |
| Format: | Artikel |
| Sprache: | English |
| Veröffentlicht: |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
1999
|
| Schriftenreihe: | Semiconductor Physics Quantum Electronics & Optoelectronics |
| Online Zugang: | http://dspace.nbuv.gov.ua/handle/123456789/117925 |
| Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Zitieren: | Dissolution of indium arsenide in nitric solutions of the hydrobromic acid / Z.F. Tomashik, S.G. Danylenko, V.N. Tomashik // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 1. — С. 80-83. — Бібліогр.: 9 назв. — англ. |
Institution
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
irk-123456789-117925 |
|---|---|
| record_format |
dspace |
| spelling |
irk-123456789-1179252017-05-28T03:04:17Z Dissolution of indium arsenide in nitric solutions of the hydrobromic acid Tomashik, Z.F. Danylenko, S.G. Tomashik, V.N. Dissolution of InAs in HNO₃-HBr-H₂O solutions is studied. The surface of equal etching rates is constructed, and the limiting stages of the dissolution process are determined. Depending on the [HNO₃]/[HBr] ratio, InAs dissolution may be limited by kinetic, or diffusion, or combined mechanisms. The dissolution rate of InSb in these solutions is rather low, and the etched surface is covered with a friable sediment. HNO₃ -HBr-H₂O solutions can be employed for a dynamic chemical polishing of InAs with a variable etching rate. 1999 Article Dissolution of indium arsenide in nitric solutions of the hydrobromic acid / Z.F. Tomashik, S.G. Danylenko, V.N. Tomashik // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 1. — С. 80-83. — Бібліогр.: 9 назв. — англ. 1560-8034 PACS 81.65 C http://dspace.nbuv.gov.ua/handle/123456789/117925 620.193 : 546.681 19 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| description |
Dissolution of InAs in HNO₃-HBr-H₂O solutions is studied. The surface of equal etching rates is constructed, and the limiting stages of the dissolution process are determined. Depending on the [HNO₃]/[HBr] ratio, InAs dissolution may be limited by kinetic, or diffusion, or combined mechanisms. The dissolution rate of InSb in these solutions is rather low, and the etched surface is covered with a friable sediment. HNO₃ -HBr-H₂O solutions can be employed for a dynamic chemical polishing of InAs with a variable etching rate. |
| format |
Article |
| author |
Tomashik, Z.F. Danylenko, S.G. Tomashik, V.N. |
| spellingShingle |
Tomashik, Z.F. Danylenko, S.G. Tomashik, V.N. Dissolution of indium arsenide in nitric solutions of the hydrobromic acid Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Tomashik, Z.F. Danylenko, S.G. Tomashik, V.N. |
| author_sort |
Tomashik, Z.F. |
| title |
Dissolution of indium arsenide in nitric solutions of the hydrobromic acid |
| title_short |
Dissolution of indium arsenide in nitric solutions of the hydrobromic acid |
| title_full |
Dissolution of indium arsenide in nitric solutions of the hydrobromic acid |
| title_fullStr |
Dissolution of indium arsenide in nitric solutions of the hydrobromic acid |
| title_full_unstemmed |
Dissolution of indium arsenide in nitric solutions of the hydrobromic acid |
| title_sort |
dissolution of indium arsenide in nitric solutions of the hydrobromic acid |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| publishDate |
1999 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/117925 |
| citation_txt |
Dissolution of indium arsenide in nitric solutions of the hydrobromic acid / Z.F. Tomashik, S.G. Danylenko, V.N. Tomashik // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 1. — С. 80-83. — Бібліогр.: 9 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
| work_keys_str_mv |
AT tomashikzf dissolutionofindiumarsenideinnitricsolutionsofthehydrobromicacid AT danylenkosg dissolutionofindiumarsenideinnitricsolutionsofthehydrobromicacid AT tomashikvn dissolutionofindiumarsenideinnitricsolutionsofthehydrobromicacid |
| first_indexed |
2025-07-08T13:01:44Z |
| last_indexed |
2025-07-08T13:01:44Z |
| _version_ |
1837083870779932672 |
| fulltext |
8 0 © 1999, Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
Semiconductor Physics, Quantum Electronics & Optoelectronics. 1999. V. 2, N 1. P. 80-83.
Introduction
Bromine-containing etchants are widely used for treat-
ment of III-V semiconducting compounds because of the
unique combination of the oxidizing and complexing
properties of elementary bromine and the softness of the
oxidizing action in comparison to that of other oxidants.
The products of oxidation are bromides that can be eas-
ily dissolved in water and many organic solvents. Even
at a low concentration of bromine, the surface of the crys-
tal under dissolution is covered with a rather thin and
dense film formed from the reaction products, so that
the process of dissolution is moved to the diffusion re-
gion (in contrast to the case of acid etchants, when the
surface is covered with a porous oxide film, which may
be hardly soluble and, in such manner hampers the pro-
cess of further oxidation) [1, 2]. Solutions of bromine in
methanol are employed most of all; however, a wider use
of this type of etchants in industry and laboratories is
restricted by the high toxicity of both components. Substi-
tution of methanol with other organic solvents dramati-
cally impairs the polishing properties of the etchant, while
using aqueous solutions of HBr as bromine solvents does
not solve the problem of etchants toxicity, too.
According to [2], the rate of InP, InAs and GaAs dis-
solution grows linearly with the rise of Br
2
concentration
in methanol. The quality of the etched surface essentially
depends on the concentration of Br
2
. Stirring of bromine-
methanol solutions significantly affects the dissolution
rate, especially at small concentrations of Br
2
. A solu-
tion of Br
2
in dimethylformamide may be used for local
dissolution of GaAs and InP [3], HBr-containing solu-
tions � for a profile etching of GaAs [4], while solutions
of saturated bromic water in HBr are recommended for
fabrication of submicron circuits on the surface of InP
and InGaAsP crystals [5]. According to [6], indium phos-
phide is solvable both in solutions of Br
2
in HBr and in
the hydrobromic acid itself, while solutions of the HNO
3
-
HBr system can be used for structural etching of InP [7].
Results and discussion
In the present work, the kinetics of InAs dissolution in
solutions of the HNO
3
�HBr�H
2
O system is studied in
reproducible hydrodynamic conditions using a rotating
disk. The initial components of the above-mentioned
compounds interact with one another to produce nitrosyl
bromide and bromine:
PACS 81.65 C; UDK 620.193 : 546.681�19
Dissolution of indium arsenide in nitric solutions
of the hydrobromic acid
Z. F. Tomashik, S. G. Danylenko, and V. N. Tomashik
Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Kyiv, 252028, Ukraine,
tel. +380 (44) 265-5755
Abstract. Dissolution of InAs in HNO
3
�HBr�H
2
O solutions is studied. The surface of equal etch-
ing rates is constructed, and the limiting stages of the dissolution process are determined. Depend-
ing on the [HNO
3
]/[HBr] ratio, InAs dissolution may be limited by kinetic, or diffusion, or
combined mechanisms. The dissolution rate of InSb in these solutions is rather low, and the
etched surface is covered with a friable sediment. HNO
3
�HBr�H
2
O solutions can be employed
for a dynamic chemical polishing of InAs with a variable etching rate.
Keywords: dissolution, etchant, indium arsenide, nitric acid, hydrobromic acid, diffusion stage,
kinetic limitations.
Paper received 23.11.98; revised manuscript received 13.04.99; accepted for publication 19.04.99.
Z. F. Tomashik et al.: Dissolution of indium arsenide in nitric solutions of ...
81SQO, 2(1), 1999
HNO
3
+ 3HBr = NOBr + Br
2
+ 2 H
2
O (1)
2NOBr = Br
2
+ 2NO (2)
HNO
3
+ 3HBr = NO
2
+ Br
2
+ H
2
O (3)
Depending on the [HNO
3
]/[HBr] ratio in a particular
solution, the bromine evolved may be dissolved in the
excess HBr to form etching mixtures similar in
composition and properties to Br
2
solutions in HBr. Al-
ternatively (in the case of [HNO
3
]/[HBr]<0.9), it can
evolve from the solution [8]. The more elementary bro-
mine is accumulated in the solution, the faster is the sub-
sequent evolution of bromine, and the sooner is the equi-
librium achieved (3). This suggests a chain-like mecha-
nism of the interaction. In the case of [HNO
3
]/[HBr]>0.8,
the growth of the bromine concentration stops, and the
equilibrium is achieved at the room temperature as early
as in 5 to 10 min after Br
2
first emerges in the solution.
On the other hand, in the case of [HNO
3
]/[HBr]<0.1, the
equilibrium is achieved no sooner than in 60 min, de-
pending on the temperature, illumination level, and some
other factors. In the presence of excess HBr, bromine is
bound in the solution almost completely, because of the
following reactions:
Br
2
+ Br - ⇔ Br
3
- (4)
2Br
2
+ Br - ⇔ Br
5
-
(5)
The rate constants for reactions (4) and (5) are 0.051
and 0.0246, respectively [6]. Therefore, the kinetics and
mechanism of InAs dissolution in solutions enriched with
HBr or HNO
3
should be essentially different, similarly
to the case of CdTe dissolutions in solutions of the same
kind [8].
The experiments were performed using single-crystal
n-type InAs wafers cut from ingots perpendicularly to
<111> direction, with the surface area of about 0.5 cm2
and thickness of 1.5 to 2 mm, charge carrier concentration
5.1016 cm�3 and mobility 30000 cm2/V.s. Prior to the etch-
ing, the wafers were mechanically polished, and the sur-
face layer of 50 to 80 µm was removed with the etchant
of the same composition as that subsequently used for
studies of the etching process. The samples were attached
to quartz substrates using pizzeine or BF-2 glue and then
mounted in a teflon holder allowing measurements in
the rotating disk mode (with the rotation rate ranging
from 36 to 120 rpm). The etching rate was determined
by the wafer thickness reduction using ICh-1 time indi-
cator. Two or three samples were etched simultaneously,
with differences in the measured thickness not exceeding
5 %. Before etching, all etchants were allowed to stand
for 40 to 60 min since the first emergence of bromine.
The solutions were prepared using 70 % extra grade
HNO
3
, 49% reagent-grade HBr and distilled water.
The process of etching is quantitatively characterized
by the rate of sample dissolution. Fig. 1 shows the dia-
gram of the InAs etching rate (µm/min) vs the HNO
3
-
HBr-H
2
O etchant composition built using the simplex
method of mathematical planning of the experiment. It
is seen from this figure that addition to HNO
3
a small
amount of HBr somewhat increases the InAs dissolu-
tion rate, which can be explained by the effect of reactions
(1-3) taking place. Then, the dissolution rate passes the
maximum and starts to decrease. Similarly to the case of
CdTe dissolution in solutions of the same type [8], this
behavior can be explained by the electrochemical mecha-
nism of InAs dissolution in HNO
3
. The reactions of the
cathodic reduction of HNO
3
and anodic dissolution of
InAs are coupled, and the rate of a process of this kind is
usually limited with the cathodic reaction, which, in its
turn, is self-catalyzed (the catalytic agent is HNO
2
). In
an acid ambient, HBr interacts with the nitrous acid
(2HBr + 2 HNO
2
= 2NO + Br
2
+ 2H
2
O), thus sharply
reducing the concentration of the catalyst and slowing
down the entire process. Depending on the [HNO
3
]/[HBr]
ratio in the solution, the effect of this interaction on the
dissolution rate will be different. In the case of InAs dis-
solution in HNO
3
� HBr - H
2
O, this effect is the most
pronounced when [HNO
3
]/[HBr] ≈ 1. When this ratio is
lower or higher, the process of dissolution is significantly
affected by the interaction between the components of
the etchant according to the reactions (1-3). As a result
of this interaction, the highest rates of InAs dissolution
are observed in the area of HBr-enriched solutions, be-
cause this is where the largest amount of elementary bro-
mine is evolving, and the process of InAs dissolution is
eventually taking place in the solutions of the Br
2
-HBr
system.
For some solutions of the HNO
3
� HBr - H
2
O system
(points II, III and IV in Fig. 1,a), the dependences of the
Fig. 1. The surface of equal etching rates (µm/min) of InAs in
HNO
3
� HBr - H
2
O solutions (a) in the composition range
A � Â � Ñ. At the nodes À, Â and Ñ, the ratio of 49% HBr :
70 % HNO
3
: H
2
O is as follows (in vol. %): À � 90 : 10 : 0;
 � 10 : 10 : 80; Ñ � 10 : 90 : 0; temperature: 24 îÑ, disk rotation
rate: 120 min�1).
Z. F. Tomashik et al.: Dissolution of indium arsenide in nitric solutions of ...
8 2 SQO, 2(1), 1999
dissolution rate (V) on the disk rotation rate (γ) are plot-
ted as V�1 vs γ- 1/2. Curves of this type may elucidate the
character of the processes underlying the dissolution [1,
2]. When the process is diffusion-limited, the curve should
pass through the coordinate origin. A larger role of the
surface (chemical) reaction in the entire process of the
dissolution results in a smaller slope of the line, and in
the case of the process limited by the rate of the chemical
reaction, the line becomes parallel to the X-axis. When
the process has a combined mechanism, the line or its
extrapolation cuts off a certain portion of the Y-axis,
whose length allows the rate constant of the overall
chemical reaction to be calculated.
It can be seen from Fig. 2 that, depending on the
composition of the solution, the process of InAs dissolu-
tion in HNO
3
� HBr - H
2
O solutions is limited by kinetic
(solution II) or diffusion (solution III) restrictions, or
has a combined mechanism (solution IV). In other words,
enrichment of the solutions with the nitric acid moves
the dissolution process to the kinetic region, while
enrichment with HBr and H
2
O gradually moves it to the
diffusion region. This conclusion is supported also by the
temperature dependences of the process of InAs dissolu-
tion in these solutions (Fig. 3). For example, dissolution
of InAs in HNO
3
-enriched solutions is indeed limited by
the kinetic stage, since the apparent activation energy of
the overall process (E
a
) is 58 kJ/mol (Fig. 3, curve I). As
the content of HBr and H
2
O in the solutions increases,
the process of dissolution moves to the diffusion region,
because the apparent activation energy is reduced to 39-
40 kJ/mol (Fig. 3, curve III).
The experimental data obtained by us made it pos-
sible to identify the range of concentrations that can be
used for dynamic chemical polishing of InAs with a vari-
able etching rate.
Our experiments on InSb dissolution in nitric solu-
tions of the hydrobromic acid have not given any posi-
tive results because of the insignificant solubility of in-
dium antimonide in solutions of this type. This is one
more justification of the fact that bromine-containing
etchants are seldom used in technological pre-processing
of InSb surface for device fabrication [1, 2]. This behav-
ior of InSb in the solutions under study can be explained
by the decomposition of SbBr
3
, which is formed in the
process, under the action of the nitric acid, with simulta-
neous oxidation of Sb+3 to Sb+5 [9], and passivation of
the surface with the compounds formed.
Fig. 2. Dependence of the InAs dissolution rate on the mixing
rate for the solutions II, III and IV of the HNO
3
� HBr - H
2
O
system (the composition of the solutions II, III and IV is indi-
cated in Fig. 1,a).
Fig. 3. Temperature dependence of the InAs dissolution rate for the solutions I and III of the HNO
3
� HBr � H
2
O system (the
composition of the solutions I and III is indicated in Fig. 1, a).
γ- �1/2, min1/2
1/V, min/µm
103/ T, K-1
ln [V, µm/min]
Z. F. Tomashik et al.: Dissolution of indium arsenide in nitric solutions of ...
83SQO, 2(1), 1999
Conclusions
Depending on the [HNO
3
]/[HBr] ratio, dissolution of
InAs in the solutions of the HNO
3
� HBr - H
2
O system
can be limited by kinetic on diffusion factors, or can be
determined by some combined mechanism. In HNO
3
-
enriched solutions, the process of dissolution is controlled
by the kinetic stages, while upon transition to HBr- and
H
2
O-enriched solutions the dissolution process is gradu-
ally moved to the diffusion region. Solutions of this sys-
tem can be used for dynamic chemical polishing of InAs
with a variable etching rate.
References
1. B. D. Luft, V. A. Perevoshchikov, L. N. Vozmilova et al.: Fiziko-
khimicheskie metody obrabotki poverkhnosti poluprovodnikov
(Physical and chemical methods for treatment of semiconductor
surfaces, in Russian). - Radio i Svyaz� Publ., Moscow, (1982).
2. V. A. Perevoshchikov: Processes of dynamic chemical polishing
of semiconductor surfaces (in Russian) // Vysokochistye Veshchest-
va. 2, pp. 5-29 (1995).
3. L. N. Vozmilova, M. M. Berdichenko: A study of local GaAs
and InP etching with dimethylformamide solution of bromine (in
Russian) // Izvestiya AN SSSR. Neorganicheskie Materialy. 16(1),
pp. 13-17 (1980).
4. S. Adochi, K. Oe: Chemical Etching Characteristic of (001) GaAs
// J. Electrochem. Soc. 130(12), pp. 2427-2434 (1983).
5. T. Matsuoka, H. Nagai: InP Etchant for Submicron Patterns // J.
Electrochem. Soc. 133(12), pp. 2484-2491 (1986).
6. P. H. L. Notten, A. A. J. M. Damen; The Electrochenistry of InP
in Br
2
/HBr Solutions and its Relevance to etching Behaviour //
Appl. Surf. Sci. 28, pp. 331-344 (1987).
7. S. N. G. Chu, C. M. Jodlauk, A. A. Ballman: New Dislocation
Etchant for InP // J. Electrochem. Soc. 129(2), pp. 352-354 (1982).
8. V. N. Tomashik, A. A. Sava: Interaction of tellurium and telluri-
um-containing semiconducting compounds with nitric solutions
of hydrobromic acid (in Russian) // Izvestiya AN SSSR. Neor-
ganicheskie Materialy. 28(2), pp. 324-328 (1992).
9. A. A. Nemodruk: Analytical Chemistry of Antimony (in Rus-
sian). - Nauka Publ., Moscow, (1978).
|