JPH01304731A - Etching method, etched mirror and etching apparatus - Google Patents

Abstract

PURPOSE:To achieve vertical etching by introducing an etching gas which is a mixture of more than 2 kinds of gas including at least one from a Br2 gas or a chemical compound gas containing Br, and other gases than those. CONSTITUTION:A mixture of more than 2 kinds of gases including at least one from a Br2 gas or a chemical compound gas containing Br, and at least one kind of gas other than those is applied as an etching gas. An etching is done by exciting the etching gas and generating an active species. Whereas the Br2 gas or the chemical compound gas containing Br stabilized a plasma discharge in low voltage range during the etching, and reduces neutral active species value of Br in an etching chamber thereby level of the chemical etching becomes controllable. Also, the neutral active species of Br accelerates the chemical etching, while ion species of other gases contribute the physical etching. Thus, forming of vertical etching surface becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The etching method of the present invention relates to dry etching of compound semiconductors and is for forming vertical etching with high precision.

The etched mirror of the present invention is formed by dry etching on a compound semiconductor, and its excellent verticality makes it suitable for use in etched mirror lasers, guiding waveguides, optical modulators, optical splitters, etc. be.

The etching apparatus according to the present invention makes it possible to stably and easily use a highly corrosive gas such as B r 2 gas or Br-containing compound gas, which is difficult to use with a mass flow controller.

In the description of the present invention, Br 2 gas or Br 2 indicates a gas state, and Br indicates a bromine atom, which may be in a gas, liquid, or solid state. The term bromine is included regardless of whether it is bromine or not. Also, Br
The containing compound gas is a gas, the Br containing compound is a gas, a liquid,
It shall include any state of solid state.

Conventional technology Conventionally, dry etching of compound semiconductors such as Ink, InGaAsP, and InGaAs has been carried out using C12 as an etchant. For example, IEICE Technical Report 5SDss-47, P35 describes reactive ion etching using C12 and Ar. (RIE) method has been reported. In this report, the etched end face is InP.
The etching rate was 50 nm/7, which was inclined at about 80 degrees with respect to the main surface of the substrate. Further, in the dry etching of G a A 8, good vertical etching has already been achieved, but the etching speed is still 01 to 06 μm/fi, which is still desired.

If (etching rate of compound semiconductor)/(etching rate of mask material) is defined as "selectivity", it is preferable to use an etching gas that has a high selectivity with respect to the mask material, and highly reactive B r 2 gas is used. In terms of use as an etching gas, the Institute of Electronics, Information and Communication Engineers 0
QE87-52. Although it has already been reported for P2O, when B r 2 gas is used alone, the etching shape becomes a so-called 6-bowing shape (Figure 3a) or a 1-tapered shape (Figure 3b), and a vertical shape is not possible. It has not been done.

In addition, normally, in order to use a substance in a liquid state as a gas,
Bromine is used by bubbling and then passed through a mass flow controller, but it is difficult to use a mass flow controller because bromine is highly corrosive. When etching is performed without using a mass flow controller, B r
2. The reality is that a large amount of gas flows and the piping system, exhaust pump, etc. become corroded and stop working after several experiments.

Currently, end mirrors of semiconductor lasers are formed by cleavage. For this reason, the laser cavity length is limited to a length that can be cleaved (approximately 260 μm) or more. Aiming at miniaturization and monolithic design, forming end faces by dry etching has been proposed and prototyped. However, at present, compared to a similar laser formed by cleavage, a laser with a cavity length of, for example, 330μ
threshold current 70 mA for m (Mikami et al.
an.

Left, 19, 213 (1983) (Electron
Letters)), and it has not yet been put into practical use.

In addition, the mirror surface formed by etching is inclined 10 to 20' from the vertical in the InP system, and G a A
In the s-type, the etching rate is very slow at about 0.1 to 0.5 μm/m, although the etching rate is quite close to vertical.

Problems to be Solved by the Invention When dry etching a compound semiconductor, if Br2 gas or a compound gas containing Br is used as an etching gas, a high selectivity with respect to the mask material can be achieved.
Very effective for etching.

However, the use of these gases as etching gases has the following problems. The first
The reason is that when B r 2 gas or a compound gas containing Br is used alone, the discharge is unstable in a low pressure region. The etching shape is the so-called "Boeing shape" (
3a) or a "tapered" shape (see FIG. 3), vertical etching is difficult. The second problem is that B r 2 gas or compound gas containing Br is highly corrosive, and for example, B r 3 produces precipitates, making it difficult to use mass flow and reducing the supply amount. If the gas flow rate is not stabilized and continued to be used without controlling the gas flow rate, it will put a strain on the pump and other exhaust systems, making them unusable.

The third problem to be solved by the present invention relates to the formation of an etched mirror by dry etching a compound semiconductor. An example of an element to which an etched mirror is applied is an etched mirror laser. The threshold current of a conventional etched mirror laser is as low as 70 mA in an InP system, which is about three times that of a laser with a mirror surface formed by cleavage, and the mirror surface is also tilted 10 to 20' from the vertical. There is. Miniaturization of optical integrated circuits.

Despite the demand for monolithic technology, these problems with mirror surface formation technology remain as a reason why it has not been put into practical use. The third problem with the present invention is the formation of a practical etched mirror surface.

Means for Solving the Problems The present invention has been made in view of the above problems. Regarding the first problem, when dry etching a compound semiconductor, an etching gas containing at least one type of B r 2 gas or a Br-containing compound gas and at least one type of other gas is used as an etching gas. Introduced as For the second problem, bromine or B
The r-containing compound is placed in a source container and cooled or heated to maintain a constant desired temperature and feed rate. This is possible because the active species of Br, a highly reactive atom, is used as the etching species. That is, the amount of active species required during etching is extremely small, and in the case of bromine, a small amount is supplied by cooling, and although it depends on the conditions of use, it shows an ideal amount of supply even in the solid state. The use of gas molecules coming out of the solid state as an etching gas was not a conventional concept. Depending on the need, the shape of the container is often chosen to have a large area in contact with the constant temperature part and a constant area of the gas-solid interface.
Use a device that is designed so that there is little change in the interfacial area between the beginning and end of the experiment.

Regarding the third problem, the following method will be used to form a practical etched mirror surface. The reflectance R of the laser is given by α, which is the inclination of the mirror surface from the vertical.
It is expressed by the formula shown below.

R/RQ=exp(-2β2w2tan2a) However,
Ro: Reflectance W when α=0; Width of light emitting spot β: Propagation constant: β=2πn/λ.

(Iga et al., Applied Optics 20, 2
367 (1981)) (Applied Optics) This equation expresses how greatly the inclination α of the mirror surface affects the laser characteristics. Decrease in reflectance by 20%
To achieve the following, it is necessary that the blur be 5° or less.

When α becomes 100, the reflectance decreases to 50%.

In the present invention, in order to provide an etched mirror laser that can be put to practical use without color loss in a laser in which a similar mirror surface is formed by cleavage, it is possible to further apply the etched mirror laser to optical waveguides, optical modulators, optical splitters, etc. In order to form the etched mirror surface obtained, it is believed that α needs to be 6° or less, preferably 3° or less. Therefore, by using a mixed gas of two or more types including at least one type of B r 2 gas or Br-containing compound gas and at least one type of gas other than these gases as an etching gas, an etching process with high reflectance that suppresses α to 3° or less can be performed. It is assumed that a mirror surface is formed.

Function The present invention uses means to solve each problem, but
The effect will be explained below in conjunction with each problem. To solve the first problem, we attempted to introduce a mixed gas of two or more types as an etching gas, including at least one type of Br2 gas or Br-containing compound gas and at least one type of other gas. This stabilizes the plasma discharge in the low pressure region during etching, reduces the amount of neutral active species of Br in the etching chamber, and controls the amount of chemical etching (which contributes to isotropic etching). made possible.

Dry etching generally has different features depending on its mechanism. Chemical etching allows for fast etching with less damage, but the shape is isotropic. Physical etching has excellent verticality and enables a well-defined shape that reflects the shape of the mask, but the etching rate is slow and damage is large.

Here, the neutral active species of Br promotes chemical etching, and the ionic species of other gases contribute to physical etching. By skillfully combining these two mechanisms, it has become possible to easily create an intermediate condition between a "bowing shape" and a "tapered shape" as an etching atmosphere, and to form a vertical etching surface. be.

Next, the second problem of the present invention will be explained. First, B
It has been found that since r 2 gas or Br-containing compound gas is highly reactive, the amount necessary for etching can be very small. For example, when using B r 2 gas, even if bromine is in a solid state at temperatures below 0°C or even lower in the supply source container, B r 2 gas will be absorbed by sublimation.
Etching can be carried out sufficiently with the amount of 2 gases. The same applies to Br-containing compound gas.

A substance with a high melting point, which is difficult to use as an etching gas according to the conventional concept, can be used as an etching gas because it contains highly reactive Br atoms. That is, the bromine or Br-containing compound is placed in a source container, cooled and optionally heated to maintain a constant desired temperature.

The bromine or Br-containing compound is in a liquid or solid state in the container, the temperature can be easily controlled, and if the exhaust volume is constant, the supply volume is also constant. By supplying only the required amount in this manner, only a very small amount of the highly corrosive Br-based gas is allowed to flow, so that the exhaust system such as the pump can be used for a long period of time without any burden. The second problem is that B r
The etching apparatus of the present invention is applicable to all etching apparatuses that use 2 gases or Br-containing compound gases, and the etching apparatus of the present invention is not limited to compound semiconductors, but can be applied to gas doping of all etching apparatuses and film forming apparatuses. It is something that

Regarding the third problem, by forming a vertical surface using the etching technique described above, reflection loss due to the slope of the surface can be eliminated and a good etched mirror can be formed. In addition, since dry etching does not depend on crystal planes, an etched mirror with high reflectance can be easily formed at a desired position. A laser using this etched mirror has a threshold current of 20 mA for a cavity length of 200 μm, which is the same level as that of a laser formed by forming a hole by cleavage, and has an excellent etched mirror that is difficult to obtain with conventional dry etching. A mirror laser could be formed.

Example Hereinafter, the present invention will be explained according to examples.

FIG. 1 is a schematic diagram of a parallel plate type RIE apparatus according to a first embodiment of the present invention. In the figure, reference numeral 8 denotes an etching chamber, in which a sample stage 2 on which a sample 1 is placed is installed. The gas is introduced through the gas supply line 11 at 0°, N2
．． N2o, N2. Inert gas.

A halogen other than bromine or a halogen-containing compound gas is supplied through a mass flow controller. When two or more types of gases are supplied, the 11 gas supply lines are branched into a plurality of lines. The gas supply line 13 is used for gases that are extremely corrosive and make it difficult to use a mass flow controller for a long period of time, such as B r 2 or Br-containing compound gas. Container 15 contains a bromine or Br-containing compound. This container 15 is contained in a constant temperature container 16 which can be set to a desired temperature. Gas supply line 13
A needle valve 14 may be used as necessary during the process. The light transmission window 7 is used when irradiating light in addition to plasma in order to selectively generate a large amount of active species during etching. A schematic groove diagram of a RIBE reactive ion beam etching apparatus having an ECR electron cyclotron resonance type plasma source is shown in FIG.

It consists of two chambers, an ECR plasma source 121 and an etching chamber 108, both of which are separated by an ion extraction electrode 120. The etching gas introduced into the ECR plasma source 121 is excited by the microwave from the microwave introduction pipe 118 and becomes plasma. Here, carp/I/1
By applying a magnetic field using No. 17, it is possible to increase the density of plasma due to the ECR effect. Gas supply lines and the like are the same as in FIG. 1.

Anisotropic etching of compound semiconductors is based on the active fi(
Basically, this is possible by using Br", Br+). However, high precision and excellent verticality are achieved by using highly reactive Br.
This cannot be achieved by using active species alone, and can only be achieved by introducing other gases.

Figures 3a and 3b are schematic diagrams of typical bowing and tapered shapes obtained by B r 2 single etching.
Figure C shows a schematic diagram of vertical etching according to the present invention. Other gases used in the present invention include 02, F2. F20. These include inert gas, halogen gas other than bromine, and halogen-containing compound gas, but the spirit of the present invention is by no means limited to these. As a gas for supplying active species of Br, B r 2
gas and Br-containing compound gas. Here, the Br-containing compound specifically includes those shown below, but is by no means limited to these.

AgBr, A3Br AsBr3. BBr3. BaB
r2-2 H20, B a B r 2 , B i
B r s , Ca B r2・6 H20, Ca
B r 2 .

Cd f3 r ・4 HOCd B r 2 ,
CoBr2 ・6 H20゜2 2 CrBr3・CF20. CuBr, CuBr2. FeB
r2-6HOFeBr2. FeBr3-6H20, Fe
Br3゜p GaBr HgBr, HgBr2. MnBr2・4H
20゜3A MnBr NbBr NiBr PbBr2,5
bBr3゜2! 5 ν 2I
SeBr 5iBr 5nBr 5nBr
5rBr2-4ri 41 2
F4IesHO5rBr TaBr
TeBr4. HBr6゜2 La 2ri
5IZnBr2. GeHBr3. GeBr4
．． SiBr4,5i2Br6゜S I HB r 3r
CB r 4+ C2B r e + (CH3)
3S I B r .

(CH3)25iBr2゜2.4-dibromoaniline C6%Br (NF2) dibromobenzoic acid C6H3Br2 (Ca2H)9.
10-dibromoanthracene C14H3Br2 dibromoethane Brα2α2B r dibromoethylene Brα-CHB r dibromo-m-xylene C6H4 (CF2Br)2 dibromo-m-xylene C6H4 (CH2Br)2 dibromoacetic acid
Br2CHCO2H2,5-dibromothiopheneC4H
2Br2S dibromonitropheno-)L/CeH2B
r 2 (0) () (No2) Dibromonitrobenzene C6H3Br2 (No2) Schiff o-E-7e/-ztz C6H3Br2 (OH) Dibromopropane B r CHfH2CH2Br Dibromobenzene C6H4Br2 Dibromopentane B r (CH2) s B r Dibromomethane CH2Br2hexabromoethane Br5C-CBr3゜hexabromobenzene 06Br6acetyl bromide) L/CH3
C0B r ethyl bromide/L/ CH3CH2Br
Prefectural carbonyl COB r Vinyl dibromide = /l/ CH2 = CHB
rMethyl bromide CH3BrTetrabromoethaneB r2CHCHB r2Tetrabromoethylene Br2C=CBr2Bromoaniline C6H4Br(NF2)1-bromo-
1,2,2-trifluoroethylene F2C=CFBr
Bromotoluene C6H4Br (C
H3) 4-p0mo2-nitropheno-/I/C6
H3Br(NO2)(OH)bromonitrobenzene
C6H4BT(NO2)Bromo7E/tI
/C6H4B r (0H)2-bromo1,3-butadiene CH2=CBrCH=CH24-bromo1-buten-3-yne CH2=CHC=CBr1-
Bromo 1-fluoroethylene CH2=CF B
rl -7”o 2-fluoroethylene FCH=
CHBτ1-bromo 1,2-difluoroethylene F
CH=CFBr1-Bromo-2,2-Schiff) v Oroethin F2C=CHBr1-Bromo-1-Rioethin
CH2=CClBr1-bromo2-chloroethylene ClCH=CHBrbromoacetic acid
BrCH2CQ2H bromo cyanide
BrCN Promostine V Ce H5CH=CHB rl-PO
Mo1.2.2-) Lichlorethylene Cl2C=CC
lBr Bromobenzene 06H5Br Bromoform CHB r aBr
2. Mix gas or Br-containing compound gas with other gases, discharge and irradiate with electron beam.

Active species are generated by light irradiation and etching is performed.

At this time, since the amount of B r 2 gas or Br-containing compound gas generally required for etching is small, even if it is a high melting point compound or a compound with low vapor pressure, it is used by the above-mentioned gas supply method that does not use mass flow. Things become possible.

In the present invention, the mask material has a higher selection ratio of Si.
N SiOTi and TiO2 are used.

Next, a second embodiment of the present invention will be described.

After cleaning the InP substrate, Si
A 3N4 film was deposited in an amount of 100 to 300 nm, and 200 nm of Ti was further deposited on top of it by EB (electron beam) evaporation.
oo~60oO people were formed. Ti.

A resist was applied and exposed as a mask for etching the Si3N4 film, and this was placed in a dry etching apparatus, and Ti was etched using CCl4 as an etching gas. Next, the S 13 N4 film was etched using CF4, and the resist was removed to form an InP mask.

The following etching was performed using the parallel plate type RIE apparatus shown in FIG. First, a mask was formed using the method described above.
The nP substrate is placed on the sample stage 2, and vacuum is applied.

The ultimate degree of vacuum at this time is I x 10-5 to I x 1
0-'Torr. Ar was introduced from the gas supply line 11 at a rate of 0.1 to 20 sCam. Bromine is placed in the container 16, cooled to -40 to 10°C to maintain a constant temperature, and then passed through a needle valve to the etching chamber 8 from the gas supply line 13.
Br gas was introduced into the interior. The needle valve 14 used here has been subjected to corrosion resistance treatment.

Plasma was generated by discharge and electricity. The RF power density at this time is 0.1 to 1. e W/d and the gas pressure in the etching chamber were 1 to 20 mTorr. The substrate temperature is not controlled, water-cooled, or heated as necessary. After etching to the desired depth, the gas introduction pulp is closed and the ultimate vacuum is 1 x 10 - I x 10-'
Vacuum is applied until Tarτ is reached, and then the sample is taken out. After surface cleaning, the etched shape was observed under a microscope. A schematic diagram thereof is shown in FIG. 3C. Br2
If etching is performed using gas alone, the shape shown in Figure 3a and b will be formed depending on the etching chamber pressure and RF power, and the shape shown in Figure 3C cannot be formed by vertical etching. Ta. However, by mixing Ar, vertical etching became possible and an excellent shape as shown in FIG. 3C was obtained. Further, at this time, etching was performed at a very high etching rate of 1.6 to 3.0 μm/gin.

Next, a third embodiment of the present invention will be described.

A S 102 film was deposited on a GaAs substrate to a thickness of 2,000 to 1000 yen by photo-CVD, and this was processed into a mask material. Etching was carried out using the parallel plate type RIE apparatus shown in FIG. A sample was placed on the sample stage 2, and the sample was evacuated in the same manner as in the second example. Gas supply line 1
He was introduced from No. 1 at a rate of 0.1 to 20 sCam, and similarly to the second example, B r 2 gas was introduced from the gas supply line 13, and etching was performed by plasma discharge. At this time, the etching speed was 0.5 to 3 .mu.m1w1n, and extremely high-speed etching, which could not be obtained by conventional etching, was realized. At the same time, the etched shape at this time was the vertical shape shown in FIG. 3C, similar to the second embodiment.

In the fourth example, an etched mirror was formed using the parallel plate type RIE apparatus shown in FIG. 1, and this was applied to a semiconductor laser.
An example will be described below.

On an n-type InP substrate 301, an n-type cladding layer 302 and an active layer (InGaAsP) 303.1) type cladding layer 3 are formed.
After forming the os using the LPE (liquid phase epitaxy) method, reverse mesa etching is performed, and then p-type InP304. Stripes were filled with n-type Inp306 (see Figure 4).

A Si3N4 film and a Ti film were formed on the entire surface, and a mask was formed in the same manner as in the second example.

The sample was placed on the sample stand 2 in the etching chamber, and the sample was sufficiently evacuated. Supply N2 from the gas supply line 11 to Q, 1~
20 g of CCm was introduced, B r 2 gas was introduced as in the second example, and plasma discharge was performed to form an etched mirror. Thoroughly vacuum, take out the sample and clean the surface.
The mask material was removed using an etching solution of F:NH4F=1:1o. The depth of the etched groove 500 formed is 5 to 1
It was 0 μm.

After vapor depositing A u/Z n/A u as a p-type electrode, an ohmic contact was formed using a lift-off method to a thickness of 100 mm.
After polishing to μm, Au/Sn/Au is used as an n-type electrode on the back side.
was founded. One end surface was formed by cleavage, and the laser characteristics were measured. The current-light output characteristics were measured and the oscillation threshold current was examined, and it was found to have very excellent characteristics of 10 to 30 mA, comparable to that of a laser formed by cleaving both ends. It can be seen that the optical output of the laser largely depends on the inclination α of the mirror surface, and that an etched mirror with superior laser characteristics is formed. The etched mirror according to the present invention is not limited to lasers, but can also be used in optical waveguides and optical modulators.

It is widely applied to optical splitters, etc.

Next, a fifth embodiment of the present invention will be described.

Etching was carried out using a RIBE apparatus having an ECR ion source as shown in FIG.

TiO2 was deposited on a GaAs substrate and processed to form a mask. This sample is mounted on a sample stage 102 in the etching chamber. This sample stage 102 can be rotated during etching.

After evacuation to 1×10 Tort or less, H2 gas was introduced from the gas supply line 11. Bromine is placed in the container 15, cooled to -40 to 10°C, kept at a constant temperature, and then connected to the gas supply line 1.
3, B r 2 gas was introduced.

Microwave power 200W, ion extraction voltage 100~9
00■, gas pressure in the etching chamber 0.1-6mTor
Etching was performed at r. The sample stage was rotated as necessary. After the etching was completed, the sample was sufficiently evacuated and then the sample was taken out and the surface was cleaned. The etched surface obtained was vertical and extremely smooth.

Next, a sixth embodiment of the present invention will be described.

A TiO2 mask was formed on the InPjiW board, and etching was performed using the RIE apparatus shown in FIG.

The introduced gases are 0 and B r 2 . Plasma discharge was performed under the same conditions as in the second example. Furthermore, a mercury lamp was irradiated through the light iη filter window 7 to promote the generation of active species. After the etching was completed, the sample was sufficiently evacuated, then Ar was introduced, and the sample stage was heated to 100 to 300° C. for about 30 minutes. thus? The etched sample had a good etched surface with relatively little damage to the etched surface. In the vertical direction, it was improved compared to using B r 2 gas alone.

Next, a mask was formed using S x 02 on the InP substrate, and a sample was placed thereon as in the second example. 0.6 to 30 scam of water vapor was introduced from the gas supply line 11, bromine was introduced into the container 16, and etching was performed in the same manner as in the second example. It was confirmed that the verticality of the etched surface was improved compared to when using Br2 gas alone.

Next, a mask was formed using S i 02 on the G a A B substrate, and a sample was placed thereon as in the second example. pHe was introduced from 0.5 to 301,100 m through the gas supply line 11, and SiBr4 was placed in the container 16, which was kept at a constant temperature of -6°C to 20"C. SiBr4 gas was introduced into the etching chamber through the gas supply line 13. When etching was performed in the same manner as in the second example, a good etched surface with little damage was obtained.The etching rate was 0.
．． 6-2. It was o/1m/so-called in.

Next, a seventh embodiment of the present invention will be described.

Etching was carried out using a RIBE apparatus having an ECR ion source shown in FIG. The substrate was InP, the mask material was b 13N 4, and Ti was further layered thereon, and they were installed in an etching chamber.

After evacuation to 1x10 Torr or less, C12 gas was introduced from the gas supply line 11 at 05 to 20 scem, and dibromoethylene was placed in the container 15 at a temperature of -20°C to 20°C.
The temperature was maintained at a constant value within 0°C. 21 Dolha/L/ 7” 1
4, dibromoethylene gas was introduced into the etching chamber from the gas line 13. Microwave power 200W,
As a result of etching at an ion extraction voltage of 100 to 900 V and a gas pressure of 0.1 to S mTorrK at 700°C, a good etched surface with little damage was formed. Etching rate is 0.3-1.5μm/i
It was H.

Effects of the Invention In the present invention, to solve the first problem, that is, the inability to obtain a perpendicular etched surface, a method containing at least one Br2 gas or Br-containing compound gas and at least one other gas, We planned to introduce a mixture of two or more types of gases as etching gases, and this made it possible to achieve very excellent vertical etching.

The second problem is that Br2 gas or compound gas containing Br is highly corrosive, making it difficult to use a mass flow control roller, making the supply amount unstable, and putting a strain on pumps and other exhaust systems. In response, we have invented an apparatus that allows bromine or Br-containing compounds to be placed in a supply source container, cooled or heated as necessary, and kept at a constant temperature. This facilitates the use of B r 2 gas or Br-containing compound gas, which was conventionally difficult to handle as an etching gas. It was also shown that substances with high melting points, which have not been used as etching gases, can also be used as etching gases. It has become possible to stably supply small amounts of these gases necessary for etching, and it has become possible to perform etching without putting much burden on pumps or other exhaust systems.

;) Regarding the problem of i3, that is, the inclination angle of the etched mirror, by using the etching apparatus according to the present invention and forming the etched mirror by the etching method according to the present invention, it is possible to obtain a very excellent vertical etched surface. . As a result, in a semiconductor laser, for example, characteristics comparable to those obtained by forming a mirror surface by cleavage can be obtained. Furthermore, since RIE is used, the etching is anisotropic, and an etching mirror can be formed at a desired position. This means that the cavity length of semiconductor lasers, which was previously limited to the length that could be cleaved (200 to 300 μm or more), has now become miniaturized and monolithic, and its industrial contribution. The degree is very large. In addition to semiconductor laser mirrors, optical waveguides, optical modulators,
It is also very useful as a mirror for optical splitters and the like.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram showing a parallel plate type RIE apparatus used in an example of the present invention, and Figure 2 is an E
A schematic configuration diagram showing a RIBE apparatus having a CR ion source,
Figure 3a shows "B r 2 gas alone etching"
b is a 6-tapered shape, C is a schematic cross-sectional view of vertical etching in the present invention, and FIG. 4 is a perspective view of the element configuration of a semiconductor laser in an embodiment of the present invention. 1... ...Sample, 2...Sample stand, 3,9.
... Electrode, 4 ... Matching box, 6 ...
・High frequency power supply, 6...Exhaust line, 7...
...Light transmission window, 8...Etching chamber, 11゜1
3... Gas supply line, 14... Needle valve, 16... Container, 16...
Constant temperature container, 1o1...Sample, 102...
・Sample stand, 106...Exhaust line, 108...
... Etching chamber, 117 ... Coil, 1
18...Microwave introduction tube, 119...
・Quartz window, 120...Ion extraction electrode, 12
1...ECR plasma source, 20o...
Mask, 201... Compound semiconductor, 301...
... n-InP substrate, 302... old... n-cladding layer (n-InP'), 303... active layer (In
GaAsP), 3o4...p-buried layer (p-I
nP), 305...p-cladding layer (p-In
P), 306... n-buried layer (n-InP). Name of agent: Patent attorney Toshio Nakao and one other person I
-m-sample? --1 Test fP+ Mortar 3.9--1 Electrode 4- Alignment 5 5- High Question R9 Clearance 6- Exhaust line 7- Light transmission window 8- Edge + End display 11.13- Gas supply line f4 - 21 Dollar Panoreb 15 --- Answer Figure 1 16- Constant Temperature 3 Kyo 101 --- Sample 10f! -m-Sample stand to6- Exhaust line 10B-11 Etschatsu chamber/l'? ---Coil 11B-11 Micro J Pekinei II'/-11 stone moxibustion window 120- Ion 31 output electricity IF! I-E C scale plasma 5 200--Mask material (Q) (b) IC) 30/-n -1nF f-excluded 302-n cladding ji (n-1nP) 303-m-active layer (In GaASP), v6-n buried g4 (n
-xnp) Figure 4

Claims (9)

[Claims] (1) When etching a compound semiconductor placed in a vacuum container, at least one Br_2 gas or Br-containing compound gas and at least one other gas are used.
An etching method characterized in that a mixed gas of two or more species containing a species is used as an etching gas, and the gas is excited to generate active species to perform etching. (2) Inert gas, oxygen (O_2) as etching gas,
The etching method according to claim 1, characterized in that the etching method contains at least one of nitrogen (N_2), hydrogen (H_2), halogen gas or halogen-containing compound gas other than Br_2 gas. (3) The etching method according to claim 1, wherein the compound semiconductor contains indium (In) and phosphorus (P), or gallium (Ga) and arsenic (As) as main components. (4) Silicon nitride (Si_3N_4), silicon oxide (S
iO_2), titanium (Ti), titanium oxide (T
2. The etching method according to claim 1, wherein the etching is performed using at least one substance of iO_2) as a mask. (5) 1 for recovery of surface damage caused by etching
2. The etching method according to claim 1, wherein the etching process is performed at a temperature of 00 to 300°C. (6) Heat treatment atmosphere: vacuum, H_2, N_2, Ar,
6. The etching method according to claim 5, wherein the etching method is carried out in He. (7) Contains at least one Br_2 gas or Br-containing compound gas and at least one other gas;
An etched mirror formed by using a mixed gas of two or more types as an etching gas, exciting the gas to generate active species, and etching a compound semiconductor. (8) When introducing Br_2 gas or Br-containing compound gas into the etching chamber, the container containing bromine or Br-containing compound is connected to the etching chamber through piping, and by heating or cooling the temperature of the container, An etching apparatus characterized by adjusting the supply amount of Br_2 gas or Br-containing compound gas. (9) The etching apparatus according to claim 8, further comprising a needle valve to adjust the flow rate of Br_2 or Br-containing compound gas.