JPH1168251A - Semiconductor device, semiconductor light emitting device and method of manufacturing the same - Google Patents

Abstract

(57) [PROBLEMS] Particularly, in a semiconductor laser device using a II-VI group compound semiconductor, a novel etching stop layer is used to enhance the controllability of the ridge shape, and a highly accurate and low damage device structure and the device structure. It is intended to provide a manufacturing method. SOLUTION: By providing an etching stop layer 207 made of a ZnSSeTe mixed crystal between a first cladding layer 206 and a second cladding layer 208, a sufficient etching selectivity can be obtained when etching the second cladding layer. be able to. As a result, the distance between the current blocking layer 212 and the light guide layer 205c can be precisely controlled, and damage to the crystal can be suppressed. As a result, the characteristics of a semiconductor laser device using a II-VI compound semiconductor can be reduced. Can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly to a laser device comprising a II-VI compound semiconductor, a method of manufacturing the same, and an optical disk apparatus using the same. .

[0002]

2. Description of the Related Art II-VI compound semiconductors are expected as materials for realizing short wavelength optical devices. Conventional II-V
As a semiconductor laser device using a group I compound semiconductor,
A gain-guided stripe electrode structure has been proposed (for example, Applied Physics Letters, May 1991).
9, 1272). This is a type of laser in which light is amplified along a high gain region below the stripe electrode and leads to oscillation.

However, the semiconductor laser having the stripe electrode structure has the following problems. The first problem is that the current injected into the stripe electrode spreads to a region other than the lower part of the stripe electrode, so that the injection efficiency is reduced and the laser characteristics such as current-light intensity characteristics are low. Second, when the injection current is increased, oscillation occurs in a higher-order waveguide mode, and it is difficult to maintain stable oscillation in the fundamental mode.

To solve these problems, a refractive index guided element has been proposed. In these devices, a stripe-shaped ridge is formed in the device, an injection current is confined in the ridge portion, and a guided light is confined by providing a refractive index difference between the inside and the outside of the ridge. Conventionally, a process such as ion milling or dry etching has been used to form the ridge region, and the etching depth, that is, the height of the ridge portion has been controlled by controlling the etching time.

[0005]

The height of the ridge is an important parameter for determining the electrical and optical characteristics of the laser device, and strict control is required especially for the refractive index waveguide device. However, in the conventional control based on the etching time, the etching rate fluctuates due to the fluctuation of the etching conditions and the in-plane distribution of the wafer to be etched, and the etching depth varies. Also,
In the etching by the dry process, physical damage (damage) due to colliding ions or plasma occurs on the etched surface, and there is a problem that crystal quality is deteriorated. Although wet etching using a solution does not cause any damage, fluctuations in the etching rate and in-plane distribution are further increased, so that it has been extremely difficult to apply the refractive index waveguide device to ridge formation. Such problems occur only in II-VI
This is because an appropriate etching stop layer for selectively etching the group III compound semiconductor has not been established.

On the other hand, recently, ZnCdS (Japanese Patent Laid-Open No. 9-10263)
0) and an etching stop layer using CdZnMgSSe (Japanese Patent Application Laid-Open No. 7-202346) have been proposed, but the etching rate ratio (selectivity) between the material to be etched and the etching stop layer is not sufficient, and There was a problem that the surface flatness later deteriorated.

As described above, the conventional II-VI compound semiconductor-based semiconductor device has a problem that an appropriate etching stop layer for selectively etching the II-VI compound semiconductor has not been established. It has been difficult to obtain II-VI group compound semiconductor based semiconductors with good reproducibility, such as refractive index guided semiconductor lasers, which require high precision and low damage structures.

Accordingly, an object of the present invention is to provide a novel semiconductor device of high precision and high quality using a novel etching stop layer and a method of manufacturing the same, in order to solve the above-mentioned problems of the prior art.

[0009]

Means for Solving the Problems In order to achieve the above object, a semiconductor device of the present invention comprises a II-VI compound semiconductor containing at least Te as a group VI element constituting a II-VI compound semiconductor. A first semiconductor layer and a III-V compound semiconductor provided on the first semiconductor layer or II-V containing no Te or containing Te, but having a lower Te composition than the first semiconductor layer.
A second semiconductor layer made of a group I compound semiconductor, and an opening reaching the first semiconductor layer is provided in a part of the second semiconductor layer.

Further, the semiconductor device of the present invention contains at least Te as a group VI element constituting a group II-VI compound semiconductor.
A structure in which a first semiconductor layer made of a II-VI compound semiconductor is provided on a substrate, and an opening is provided so as to remove a part of the substrate from the substrate to the first semiconductor layer; Has become.

Further, the present invention provides a semiconductor light emitting device comprising: a double heterojunction having an active layer composed of a II-VI compound semiconductor; and a light guide layer provided above and below the active layer. A first semiconductor layer made of a II-VI compound semiconductor containing at least Te as a group VI element constituting a II-VI compound semiconductor provided directly on the portion or via a first cladding layer. And a second semiconductor layer made of a II-VI compound semiconductor that does not contain Te or contains Te but has a smaller Te composition than the first semiconductor layer provided on the etching stop layer. And a striped second clad layer.

Further, the semiconductor light emitting device of the present invention has a II-VI
A double heterojunction having an active layer composed of a group III compound semiconductor and light guide layers provided above and below the active layer, and provided directly on the double heterojunction or via the first cladding layer II-VI containing at least Te as a group VI element constituting the obtained II-VI compound semiconductor
An etching stop layer composed of a first semiconductor layer composed of a group III compound semiconductor and a second semiconductor composed of a II-VI group compound semiconductor containing no Te or containing Te but having a smaller Te composition than the first semiconductor layer The structure includes a current confinement layer formed of a layer and having a stripe-shaped opening, and a second cladding layer provided in the opening.

The semiconductor light-emitting device of the present invention is a surface-emitting semiconductor light-emitting device provided on a substrate, wherein the light-emitting layer has a light-emitting layer.
A first semiconductor layer made of a II-VI compound semiconductor, and a first semiconductor layer made of a II-VI compound semiconductor containing at least Te as a group VI element constituting the II-VI compound semiconductor is provided between the substrate and the light emitting layer; , From the substrate to the first semiconductor layer, the opening is provided to remove a part of the substrate.

Further, the method of manufacturing a semiconductor device according to the present invention comprises the steps of II
Forming a first semiconductor layer made of a II-VI compound semiconductor containing at least Te as a group VI element constituting the group VI compound semiconductor; and forming a III-V compound semiconductor or Te on the first semiconductor layer. Forming a second semiconductor layer made of a II-VI compound semiconductor containing no or containing Te but having a smaller Te composition than the first semiconductor layer; and using the first semiconductor layer as an etching stop layer. And selectively etching the second semiconductor layer.

Further, the method for manufacturing a semiconductor device according to the present invention
Forming a first semiconductor layer made of a II-VI compound semiconductor containing at least Te as a group VI element constituting a II-VI compound semiconductor on a substrate, and using the first semiconductor layer as an etching stop layer Selectively etching the region from the substrate to the first semiconductor layer.

Further, the method of manufacturing a semiconductor device according to the present invention
Forming a first semiconductor layer made of a II-VI compound semiconductor containing at least Te as a group VI element constituting a II-VI compound semiconductor on a substrate; And selectively etching the first semiconductor layer while leaving the II-VI group compound semiconductor having a smaller Te composition than the semiconductor layer.

[0017]

According to the present invention, a high-precision and high-quality II-VI compound semiconductor device using a novel etching stop layer can be realized. According to the study of the present inventors, the etching rate of a first semiconductor layer made of a II-VI compound semiconductor containing at least Te as a group VI element constituting a II-VI compound semiconductor is a III-V compound semiconductor. A second semiconductor made of a II-VI group compound semiconductor containing no semiconductor or containing Te or containing Te but having a smaller Te composition than the above-mentioned first semiconductor layer;
It has been found that the etching rate of the semiconductor layer can be sufficiently reduced. Therefore, when the first semiconductor layer is used as a base of the second semiconductor layer, the second semiconductor layer is etched when the second semiconductor layer is etched. The semiconductor layer provided below the first semiconductor layer and the first semiconductor layer (on the substrate side) can be prevented from being etched. Therefore, the second semiconductor layer can be selectively etched, so that a new II-VI compound semiconductor-based semiconductor element that has not been obtained conventionally can be formed.

In order to fabricate a semiconductor laser device of the refractive index guided type, it is necessary to precisely control the etching depth for producing a refractive index step in the lateral direction and to suppress damage to the crystal during etching. is important. Conventionally, since there was no appropriate etching stop layer, the device characteristics were low and the reproducibility of device fabrication was low. However, the present invention can realize a high-precision and low-damage refractive index guided semiconductor laser device.

That is, according to the third and fourth aspects of the present invention, the position of the etching stop layer constituted by the first semiconductor layer provided directly on the double hetero junction or via the first cladding layer. However, since the etching end point is defined, the distance between the light guide layer (or active layer) and the current confinement layer (that is, the lateral light confinement layer) can be strictly controlled.

Further, in the case of a surface-emitting type light emitting device such as a vertical cavity type semiconductor laser device or a light emitting diode of a back emission type, the substrate of the light emitting portion is etched or the like for the purpose of removing light absorption by the substrate on the back surface. Need to be removed. In particular, in the vertical cavity surface emitting laser device, when the position of the surface on which the cavity mirror is formed fluctuates from the design position, the intensity of the guided light in the active layer is reduced, and the gain of laser oscillation is greatly reduced. Further, when the etched surface is roughened, the reflectance of the resonator mirror decreases, and the loss of the element increases. In any case, the element characteristics deteriorate, so that the etching end position and the surface smoothness of the etched surface are important. Conventionally, the control was difficult, but the present invention can realize a high-precision and high-quality surface-emitting type light-emitting element.

That is, when the first semiconductor layer is used as in claims 2, 5, and 8 of the present invention, after the semiconductor element is formed, the first semiconductor layer is formed from the substrate side on which the element is formed to the first semiconductor layer. When the region is etched, the first semiconductor layer and the semiconductor layer provided above the first semiconductor layer (on the side opposite to the substrate) can be prevented from being etched. Therefore, it becomes possible to selectively etch the substrate and the like,
It becomes possible to form a novel II-VI compound semiconductor-based semiconductor element that has not been obtained conventionally.

According to the study of the present inventors, it is possible to perform etching having a selectivity opposite to that described above under different etching conditions. That is, II containing at least Te as a group VI element constituting the II-VI group compound semiconductor
The etching rate of the first semiconductor layer made of a group-VI compound semiconductor is III-V compound semiconductor or does not contain Te or contains Te, but has a smaller Te composition than the first semiconductor layer.
It has been found that the etching rate can be sufficiently higher than the etching rate of the second semiconductor layer made of a group I compound semiconductor. Therefore, after using the first semiconductor layer as an etching stop layer, only the etching stop layer exposed on the etching surface can be selectively removed, so that the etching accuracy can be further improved.

The semiconductor device and the method of manufacturing the same according to the present invention include a semiconductor laser device, a light emitting diode device, an IC,
This is useful for semiconductor devices such as SI. In particular, the effect of the present invention is exerted in a portion that includes a II-VI compound semiconductor as a constituent material and requires processing of an element shape with high precision and low damage.

Further, the optical disk device of the present invention is useful as an information reading device or a storage device of a computer, and a reproducing device or a recording / reproducing device of video information and audio information.

The semiconductor light emitting device according to the fifth aspect of the present invention is used for a surface emitting type semiconductor laser device or a back-emitting type light emitting diode, whereby the shape accuracy and reproducibility are improved, and the device characteristics are improved. be able to.

The double hetero junction according to the third and fourth aspects of the present invention refers to a semiconductor laser structure composed of a II-VI compound semiconductor, such as a single quantum well type or a multiple quantum well type. An active layer having a structure and emitting light by current injection; and II- provided at an upper portion and a lower portion of the active layer.
5 shows a region of a light guide layer formed of a group VI compound semiconductor. Further, when the active layer is a multi-quantum well type or the like, the active layer also functions as an optical waveguide, and the active layer region indicates a region of the active layer in a structure in which the active layer and the cladding layer are directly in contact without using an optical guide layer. .

The group II-VI compound semiconductor used in the semiconductor device of the present invention includes Zn, Cd, Mg, Mn, B
e, one or more divalent elements of Ca and S, S
It is preferable to use a compound comprising at least one of Group VI elements of e and Te. II-VI compound semiconductors obtained by selecting from the above elements (for example, Zn _x Cd _{1 -x} S _y S
e _{1 -y} , Zn _x Cd _{1 -x} S _y Te _{1 -y} , Zn _x Mg _{1 -x} S _y Se
_1-y , Zn _x Mn _1-x S _y Se _{1 -y} (0 ≦ x ≦ 1, 0 ≦ y ≦
1) etc.) have a lattice constant of 0.53 nm to 0.67
Since it can be largely changed within the range of nm, it can be matched with the lattice constant of the n-type (or p-type) layer of a semiconductor composition device such as a laser device.

The first semiconductor layer of the present invention comprises Zn, Cd,
A compound comprising at least one divalent element selected from Be, Mg, Mn and Ca, and at least one group VI element selected from S and Se and Te, and the Te composition x is 0.1 ≦ x ≦ 1 Preferably, there is. GaA
When forming an element on an s substrate or a ZnSe substrate,
ZnSTe, ZnSSeTe, BeZnSeTe, Be
ZnSSeTe, CdZnSTe, or MgZnSS
It is preferable to use a mixed crystal of eTe as the first semiconductor layer, because not only the etching rate but also the lattice distortion can be reduced.

When the II-VI group compound semiconductor is used as the second semiconductor layer of the present invention, the above-mentioned constituent elements can be used, but the Te composition y of the second semiconductor layer is 0 ≦ y ≦ 0.8.
Where y ≦ x− with respect to the Te composition x of the first semiconductor layer.
Satisfying the relationship of 0.1 is preferable because a sufficient etching rate selectivity can be secured. By setting y ≦ x−0.3, a higher selectivity can be obtained.

Since the first semiconductor layer has a composition that lattice-matches with the crystal lattice of the substrate material on which the first semiconductor layer is formed, the quality of the semiconductor element can be improved even if a relatively thick etching stop layer is formed. Desirable without lowering. Specifically, it is possible to realize an etching stop layer is lattice-matched to GaAs substrate by using a mixed crystal such as ZnS _0.65 Te _{0 .35} and ZnS _0.4 Se _0.4 Te _0.2.

The first semiconductor layer of the present invention has a thickness of 1 nm because the etching rate can be suppressed sufficiently low.
In the range of 500 nm to 500 nm, a sufficient etching stopping ability can be provided, and when applied to a semiconductor device, a decrease in electrical and optical characteristics of the device can be suppressed. In the case of a refractive index guided type semiconductor laser device or the like, particularly high precision processing is required, and the distribution shape of the guided light is sensitive to the thickness of the etching stop layer.
In the range of nm, it is desirable because it can provide particularly high etching stopping power and good waveguide light distribution.

The thickness of the first cladding layer according to the third and fourth aspects of the present invention is an important design parameter for determining the height of the ridge, that is, the remaining thickness when the cladding layer is etched. . The stability of the guided light distribution in the transverse direction and the fundamental mode in the fundamental mode of the refractive index guided device is mainly due to the difference between the refractive index difference and the absorption coefficient between the inner and outer cladding layers of the ridge, the ridge stripe width, and It is determined by the remaining thickness after etching. If the film thickness is too small, the difference in effective refractive index between the inside and outside of the ridge becomes large and the waveguide mode becomes unstable, and a leak current may be generated too close to the active layer. If the film thickness is too large, the effective refractive index difference becomes too small, and the waveguide operates with gain guiding and cannot perform refractive index guiding. In addition, the light confinement in the lateral direction is weakened and the current spread is increased, so that the element efficiency is reduced. In order to obtain a refractive index waveguide element that oscillates in a single transverse mode, it is desirable that the thickness of the first cladding layer is between 0 and 300 nm,
Further, by setting the thickness to 50 to 200 nm, the stability of the transverse mode control is enhanced.

When the first semiconductor layer of the present invention is used as an etching stop layer, etching is performed using a neutral or alkaline solution containing at least hydrogen peroxide as an etchant, so that the etching stop layer can be formed with a high selectivity. It is desirable to be able to leave. Especially pH 8 ~
A high selectivity can be easily obtained with a mixed solution of aqueous ammonia and aqueous hydrogen peroxide between 11 and 11.

In the case of selectively removing the first semiconductor layer of the present invention, only the first semiconductor layer is etched by using an acidic solution containing at least dichromate ions or permanganate ions as an etchant. It can be removed with a high selectivity. In particular, a high selectivity can be easily obtained with a mixed solution of potassium dichromate and sulfuric acid.

Since the etching stop layer according to the present invention exhibits a selectivity to various etching solutions, it may be used in addition to a mixed solution of various acids such as hydrochloric acid or sulfuric acid and hydrogen peroxide, or an aqueous solution of bromine. Various etching solutions and etching conditions, such as a mixed solution of phosphoric acid and the like, an alcohol solution of bromine, and the like can be used. In the method of manufacturing a semiconductor device according to the present invention, a solution temperature at the time of etching can obtain a good selectivity at room temperature. Can also be changed.

In the following, an example of a II-VI compound semiconductor laser device and a method of manufacturing the same will be described, and specific examples will be described in detail.

(Embodiment 1) First, as shown in FIG. 1, an n-type ZnSe layer 103 is formed on an n-type GaAs substrate 102 by molecular beam epitaxy (MBE), and an n-type ZnMgSSe cladding layer 104 is further formed. , Z
nSe-based double hetero junction 105, p-type ZnMgSS
e First cladding layer 106, Zn as first semiconductor layer
An SSeTe etching stop layer 107, a p-type ZnMgSSe second cladding layer 108 as a second semiconductor layer,
p-type ZnSSe cap layer 109 and p-type ZnSe
/ ZnTe pseudo graded contact layer 110 was formed. Here, the ZnSe double hetero junction 105
Is composed of an n-type ZnSSe waveguide layer 105a, a ZnCdSe active layer 105b, and a p-type ZnSSe waveguide layer 105c. The growth temperature of the MBE method is 250 to 35
At 0 ° C., the degree of vacuum is 1 × 10 ⁻⁸ Torr. The n-type layer was prepared by introducing zinc chloride during growth, and the p-type layer was prepared by introducing nitrogen radicals during growth. In addition, ZnSSeTe etching stop layer 1
The composition of 07 is ZnS _0.4 Se _0.4 T lattice-matched to the GaAs substrate.
e _0.2 was used.

Next, a metal electrode 101 was deposited below the n-type GaAs substrate 102. Further, a striped photoresist resist mask 111 was formed on the p-type ZnSe / ZnTe pseudo-graded contact layer 110 by photolithography.

Thereafter, a photoresist resist mask 1
First selective etching was performed around 11 using a mixed solution of aqueous ammonia and aqueous hydrogen peroxide to form a striped ridge.

According to the study by the inventors of the present invention, the p-type ZnSe / ZnTe pseudo-graded contact layer 110, the p-type ZnSSe cap layer 109, and the p-type ZnSe / ZnTe pseudo-graded contact layer are etched by a mixed solution of aqueous ammonia and aqueous hydrogen peroxide. The ZnMgSSe second cladding layer 108 has 10
The etching rate of the ZnSSeTe etching stop layer 107 is as low as 1/10 or less of the etching rate of the ZnSSeTe etching stop layer 107, which is almost 1/10 min. Could be controlled with high precision.

In addition, since the etching is not a dry process such as ion milling or dry etching but wet etching using a solution, there is no damage to the crystal due to collision of ions or plasma. In addition, by performing etching halfway using a dry process and performing selective etching only at the stage of determining the ridge height in the latter half of etching, increasing the steepness of the ridge side surface, suppressing damage to the crystal, and reducing the etching end point It can also be controlled with high precision.

Next, a second selective etching was performed using an aqueous solution of potassium dichromate and sulfuric acid as an etching solution to remove the ZnSSeTe etching stop layer 107 exposed to the outside (opening) of the ridge. According to the study of the inventors of the present invention, an aqueous solution of potassium dichromate and sulfuric acid can remove a group II-VI compound semiconductor other than the etching stop layer.
Etching at a rate of about 2,000Å / min.
The etching rate of the eTe etching stop layer 107 is as high as about 10 times the etching rate. Therefore, only a portion of the etching stop layer 107 could be selectively removed by a short-time treatment without substantially etching a region below the etching stop layer 107. This second
Is performed, the ZnSSeTe etching stop layer 107 is formed at the time of the first selective etching.
In this case, a finer surface roughening can be removed to obtain a smoother etched surface, and the position of the etched surface can be controlled with higher accuracy.

By the above steps, 201 to 210 in FIG.
Can be produced.

In FIG. 2, reference numeral 201 denotes a metal electrode;
202 is an n-type GaAs substrate, 203 is an n-type ZnSe layer,
204 is an n-type ZnMgSSe cladding layer, 205 is Zn
Se-based double hetero junction, 205a is n-type ZnSSe
The waveguide layer, 205b is a ZnCdSe active layer, and 205c is p
A p-type ZnMgSSe first cladding layer, 207 a ZnSSeTe etching stop layer, 208 a p-type ZnMgSSe second cladding layer, 2
09 is a p-type ZnSSe cap layer, 210 is a p-type ZnS
5 shows an e / ZnTe pseudo graded contact layer. The second clad layer 20 as the second semiconductor layer
In the above example, a material that does not contain Te is used as 8 (a layer that is etched using the etching stop layer), but the first semiconductor layer contains no III-V compound semiconductor or Te, or contains Te. The same effect can be obtained by using a material having a smaller Te composition as compared with a certain etching stop layer 207.

Further, ZnS was vacuum-deposited on the entire upper surface of the wafer and lifted off to form a ZnS current confinement layer 212 having a thickness of 300 nm outside the ridge (opening). Here, the current confinement layer 212 has both a function as an insulating layer for confining current in the ridge portion and a function as an outer cladding layer for changing the refractive index between the inside and the outside of the ridge. This function can be separated by providing a current confinement layer on the upper part.

The current confinement layer (external cladding layer) 212 is made of a material having a lower real refractive index than the p-type ZnMgSSe second cladding layer 208, so that a difference in refractive index is provided between the inside and the outside of the ridge, and the real refractive index guide is formed. A wave-shaped refractive index waveguide element can be manufactured. Further, by using a material that absorbs light generated in the active layer, a loss-guiding type refractive index waveguide element can be manufactured. In any case, the current confinement layer (external cladding layer) 212 and the light guide layer 205 are required to enhance the effect of the refractive index guiding and to stabilize the transverse waveguide mode to the unimodal fundamental mode.
It is necessary to strictly control the distance between c, that is, the unetched thickness of the cladding layer. In the present embodiment, the p-type ZnMgSSe first cladding layer 206 determines the remaining thickness after etching, so that high-precision control was possible.

The thickness of the first cladding layer 206 is 1000 °
However, if the film thickness is too small, the difference between the effective refractive index inside and outside the ridge becomes large, and the waveguide mode becomes unstable. On the other hand, if the film thickness is too large, the effective refractive index difference becomes too small, and the waveguide operates with gain guiding, and cannot perform refractive index guiding. When ZnS is used as the current confinement layer, the stability of the transverse mode control can be increased by setting the thickness to 50 to 200 nm.

Finally, a metal electrode 211 was vapor-deposited on the current confinement layer 212 and the ridge, thereby producing a semiconductor laser device A.

The semiconductor laser device A obtained as described above uses the etching stop layer of the present invention to provide a distance between the current confinement layer (external cladding layer) 212 and the light guide layer 205c, ie, The unetched thickness of the cladding layer could be precisely controlled, and the etching interface could be kept smooth and low damage. Each of the fabricated devices oscillated at a low threshold current of 50 mA or less, and oscillated in a stable single transverse mode even when the operating current was increased to 10 times or more of the threshold. Further, the astigmatic difference of the laser element was 1 μm or less, and it was confirmed that the element was operated by refractive index guiding. The oscillation wavelength is 515 n at room temperature.
m, and the element voltage at this time was 8V.

On the other hand, in a device having the same laser structure, stripe shape, and oscillation wavelength but not using the etching stop layer, the threshold current varies, the lateral mode stability is low, and the reproducibility of device characteristics is low. It was low. This is presumably because the etching rate fluctuated depending on the flow of the etchant even in the wafer surface, and the position of the etching end point varied.

(Embodiment 2) First, as shown in FIG. 3, an n-type GaAs substrate
Forming a ZnSe layer 303, and further forming an n-type ZnMgSS
e-clad layer 304, ZnSe double heterojunction 3
05, p-type ZnMgSSe first cladding layer 306, first
ZnSSeTe etching stop layer 307 as a semiconductor layer, and high-resistance ZnMgSS as a second semiconductor layer
An e-current constriction layer 308 was formed. Here, the ZnSe-based double heterojunction 305 is connected to the n-type ZnSSe waveguide layer 30.
5a, ZnCdSe active layer 305b, and p-type ZnS
It is composed of the Se waveguide layer 305c. Also, Zn
The composition of the SSeTe etching stop layer 307 is GaAs
ZnS _0.4 Se _0.4 Te _0.2 lattice-matched to the s substrate was used. Further, the high-resistance ZnMgSSe current confinement layer 308 increases the composition of Mg and S as compared with the ZnMgSSe of the cladding layer, increases the forbidden band width while maintaining lattice matching with the GaAs substrate, that is, reduces the refractive index. ing.

Next, a metal electrode 301 was deposited below the n-type GaAs substrate 302. Further, a photoresist resist mask 309 having a stripe-shaped opening over the current confinement layer 308 was formed by photolithography.

Further, a photoresist resist mask 3
09, the first selective etching is performed using a mixed solution of aqueous ammonia and aqueous hydrogen peroxide to obtain a high-resistance ZnMgSS
A striped opening was formed in the e-current constriction layer 308. Here, if the etching is insufficient and a part of the current confinement layer remains in the opening, current injection becomes difficult, and the optical waveguide distribution is affected to make element operation difficult. Conversely, even if the etching progresses too much to affect the guide layer and the active layer, the device characteristics are greatly degraded.

According to the study of the inventors of the present invention, the high-resistance ZnMgSSe current confinement layer 308 is formed by etching with a mixed solution of aqueous ammonia and hydrogen peroxide.
The etching rate of the ZnSSeTe etching stop layer 307 is about 1 / min, whereas the etching rate of the ZnSSeTe etching stop layer 307 is as low as 1/10 or less of the etching rate. Could be controlled with high precision.

Since the etching is not a dry process such as ion milling or dry etching but wet etching using a solution, there is no damage to the crystal due to collision of ions or plasma. In addition, by performing the etching halfway using a dry process and performing selective etching only at the stage of determining the opening depth in the latter half of the etching, the steepness of the opening side is increased, and damage to the crystal is suppressed, and the etching is performed. The end point can be controlled with high precision.

Next, a second selective etching is performed using an aqueous solution of potassium dichromate and sulfuric acid as an etching solution, and the ZnSSeTe etching stop layer 3 exposed at the opening is formed.
07 was removed. According to the study of the inventors of the present invention, an aqueous solution of potassium dichromate and sulfuric acid also etches II-VI group compound semiconductors other than the etching stop layer at a rate of about 1000 ° / min, but the ZnSSeTe etching stop layer 307 Is very fast, about 10 times the etching rate. Therefore, by a short time treatment, only the etching stop layer 307 could be selectively removed without substantially etching the region below the etching stop layer 307. By performing this second selective etching, ZnS is used in the first selective etching.
The fine surface roughness generated in the SeTe etching stop layer 307 can be removed to obtain a smoother etched surface, and the position of the etched surface can be controlled with higher accuracy. Further, in this structure, the etching stop layer can be removed from the current injection region, that is, the region where light is confined, and further, there is an effect of smoothing the regrowth interface, so that the device characteristics can be improved.

By the above steps, 401 to 408 in FIG.
Could be produced. In FIG. 4, 4
01 is a metal electrode, 402 is an n-type GaAs substrate, 403 is an n-type ZnSe layer, 404 is an n-type ZnMgSSe cladding layer, 405 is a ZnSe double heterojunction, 405a
Is an n-type ZnSSe waveguide layer, 405b is a ZnCdSe active layer, 405c is a p-type ZnSSe waveguide layer, and 406 is a p-type Z
nMgSSe first cladding layer, 407 is ZnSSeTe
An etching stop layer 408 indicates a current confinement layer. Note that, in the above example, a material containing no Te was used for the current constriction layer 408 (layer etched using the etching stop layer) as the second semiconductor layer.
A similar effect can be obtained by using a material that does not contain a group compound semiconductor or Te but contains Te but has a smaller Te composition than the etching stop layer 407 as the first semiconductor layer.

Further, the wafer is put into the MBE growth apparatus,
By performing regrowth, p-type ZnMgSSe is formed in the opening.
Second cladding layer 409, p-type ZnSSe cap layer 41
0, a p-type ZnSe / ZnTe pseudo graded contact layer 411 was grown.

In this embodiment, a ZnMgSSe mixed crystal is used for the current confinement layer (external cladding layer) 408. However, by using a material having a lower actual refractive index than the p-type ZnMgSSe second cladding layer 409, By providing a refractive index difference between the inside and the outside of the ridge, a real refractive index waveguide type refractive index waveguide element can be manufactured. Further, by using a material that absorbs light generated in the active layer, a loss-guiding type refractive index waveguide element can be manufactured. In any case, in order to enhance the effect of the refractive index waveguide and to stabilize the transverse waveguide mode to a unimodal fundamental mode, the current between the current confinement layer (external cladding layer) 408 and the light guide layer 405c is required. The distance must be tightly controlled. In this embodiment mode, the p-type ZnMgSSe first cladding layer 406 is used.
Since the thickness of the film determined this distance, highly accurate control was possible.

The thickness of the first cladding layer 406 is 1200 °
However, if the film thickness is too small, the difference between the effective refractive index inside and outside the ridge becomes large, and the waveguide mode becomes unstable. On the other hand, if the film thickness is too large, the effective refractive index difference becomes too small, and the waveguide operates with gain guiding, and cannot perform refractive index guiding.

Finally, a metal electrode 412 was deposited on the p-type ZnSe / ZnTe pseudo-graded contact layer 411 to produce a semiconductor laser device B.

The semiconductor laser device B obtained as described above uses the etching stop layer of the present invention, so that only the current confinement layer at the opening can be selectively formed without damaging the current injection region. The etched interface that could be removed and was also the regrown surface could be maintained smooth and low damage. Each of the fabricated devices oscillated at a low threshold current of 30 mA or less, and oscillated in a stable single transverse mode even when the operating current was increased to 10 times or more of the threshold. Furthermore, the astigmatic difference of the laser element was 1 μm or less, and it was confirmed that the element was operated by refractive index guiding. The oscillation wavelength was 512 nm at room temperature, and the element voltage at this time was 7 V.

On the other hand, in the device having the same laser structure, stripe shape, and oscillation wavelength, but without using the etching stop layer, the threshold current varied and the reproducibility of the device characteristics was low. This is presumably because the etching rate fluctuated depending on the flow of the etchant even in the wafer surface, and the position of the etching end point varied.

(Embodiment 3) Next, an example of a surface-emitting type laser device using a II-VI compound semiconductor and a method of manufacturing the same will be described below, and specific examples will be described in detail.

First, as shown in FIG. 5, an n-type ZnSSeTe etching stop layer 502 as a first semiconductor layer is formed on an n-type GaAs substrate 501 by the MBE method. ZnMgSS
e clad layer 504, ZnSe-based double hetero junction 5
05, p-type ZnMgSSe cladding layer 506, p-type Zn
An SSe cap layer 507 and a p-type ZnSe / ZnTe pseudo graded contact layer 508 were formed. Here, the ZnSe-based double hetero junction 505 is formed of n-type Zn.
SSe waveguide layer 505a, ZnCdSe active layer 505b,
And a p-type ZnSSe waveguide layer 505c. Also, the ZnSSeTe etching stop layer 50
The composition of 7 is ZnS _0.4 Se _0.4 Te lattice-matched to the GaAs substrate.
_0.2 was used. Furthermore, p-type ZnMgSSe is formed by photolithography and ordinary dry etching processes.
A cladding layer 506 and a p-type ZnSSe cap layer 507,
The p-type ZnSe / ZnTe pseudo-graded contact layer 508 is processed into a circular mesa shape, and the p-type ZnSe / ZnTe pseudo-graded contact layer 5 at the center of the mesa is processed.
08 and remove the SiO ₂ / TiO ₂ DBR reflector 5
10 was produced. Thereafter, metal electrodes 51 are formed on the entire upper surface of the wafer.
1 was formed to produce a structure shown in FIG. 509
Is a current confinement layer.

Next, a photoresist having a circular opening is patterned on the GaAs substrate 501 on the back surface, and the first selective etching is performed using a mixed solution of ammonia water and hydrogen peroxide solution, and the GaAs substrate is etched as shown in FIG. A circular opening 601 was formed.

According to the study by the inventors of the present invention, the GaAs substrate 601 is etched at a high etching rate of about 1 μm / min by etching with a mixed solution of aqueous ammonia and aqueous hydrogen peroxide, whereas ZnSSeTe is etched.
The etching rate of the etching stop layer 602 is
/ 100 or less and it is hardly etched.
The position of the etched surface at the end of etching is ZnSSeT
The position of the etching stop layer 602 could be controlled with high precision.

Since the etching is not a dry process such as ion milling or dry etching but wet etching using a solution, there is no damage to the crystal due to collision of ions or plasma. In addition, by performing the etching halfway using a dry process and performing selective etching only at the stage of determining the opening depth in the latter half of the etching, increasing the steepness of the opening and suppressing damage to the crystal,
The etching end point can be controlled with high precision.

Next, a second selective etching is performed using an aqueous solution of potassium dichromate and sulfuric acid as an etching solution, and the ZnSSeTe etching stop layer 6 exposed at the opening is formed.
02 was removed. According to the study of the inventors of the present invention, an aqueous solution of potassium dichromate and sulfuric acid also etches a group II-VI compound semiconductor other than the etching stop layer at a rate of about 1000 ° / min, but the ZnSSeTe etching stop layer 602 Is very fast, about 10 times the etching rate. Therefore, only the etching stop layer 602 could be selectively removed by a short time treatment without substantially etching the region above the etching stop layer 602. At this time, the GaAs substrate 601 is hardly etched. By performing the second selective etching, fine surface roughness generated in the ZnSSeTe etching stop layer 507 at the time of the first selective etching can be removed to obtain a smoother etched surface. The control can be performed with higher accuracy. Further, in this structure, since the etching stop layer can be removed from the surface on which the DBR reflector is formed, light is not absorbed by the etching stop layer, and the smoothness of the surface on which the reflector is formed is increased, so that the efficiency of the device can be further improved. .

Further, S is formed in the opening of the GaAs substrate 602.
An iO ₂ / TiO ₂ DBR reflecting mirror 612 was formed, and a metal electrode 613 was provided around the opening to manufacture a vertical cavity semiconductor laser device C.

In order to enhance the characteristics of the surface emitting laser, it is necessary to precisely control the cavity length, that is, the distance between the lower DBR reflector 612 and the upper DBR reflector 610, so that the intensity of the guided light in the active layer is increased. There is. In addition, it is necessary to increase the reflectance of the DBR reflector. In the semiconductor laser device C obtained by the present embodiment, the position of the SiO ₂ / TiO ₂ DBR reflecting mirror 612 can be positioned with good reproducibility by using the etching stop layer of the present invention, so that the The vessel length could be controlled precisely. Also, since the etching interface was able to be kept smooth and low damage, the DBR
The reflectivity of the reflecting mirror could be increased to 99.8% or more. Each of the fabricated devices oscillated at a low threshold current of 5 mA or less. The oscillation wavelength was 495 nm, and the element voltage at this time was 12 V.

On the other hand, devices having the same laser structure and oscillation wavelength but not using the etching stop layer had variations in threshold current, and many devices did not oscillate. This is probably because the position of the etched surface varied and the element efficiency decreased, and the reflectance of the DBR reflecting mirror decreased due to the rough surface of the etched surface.

The semiconductor laser according to the embodiment of the present invention has been described above. In the first or second embodiment, a single quantum well type semiconductor laser device has been described as an example. The present invention is not limited to a semiconductor laser device, and can be applied to a semiconductor laser device having another structure such as a multi-quantum well type or a buried structure. The present invention can also be applied to an element having no independent light guide layer.

In the first or second embodiment,
The composition of the ZnSSeTe etching stop layer was changed to ZnS _0.4 Se
_0.4 Te _0.2 , but other GaAs such as ZnS _0.65 Te _0.35
The same effect can be obtained by using a composition that lattice-matches with the s-substrate, and a mixed crystal having a composition that does not lattice-match can be used if the film thickness is sufficiently thin, 50 nm or less.

Further, in the first or second embodiment, the etching stop layer is provided between the first clad layer and the second clad layer, that is, inside the clad layer. Instead, it can be provided directly in contact with the light guide layer, or can be further provided inside the light guide layer. An etching stop layer may be provided on the substrate side of the active layer depending on the element structure such as a buried structure.

In Embodiment 1 or 2,
Although ZnS or ZnMgSSe is used for the current confinement layer, another material such as ZnO or ZnSSe mixed crystal can be used. ZnTe or ZnSeTe mixed crystal, CdZn
By using a Se mixed crystal, GaAs, or the like, a loss guided element can be manufactured.

Although the first to third embodiments have dealt with semiconductor laser devices, the present invention can be applied to other II-VI compound semiconductor devices such as light emitting diode devices and photodiode devices.

In the first to third embodiments, n-type GaAs is used.
Although a II-VI compound semiconductor is grown directly on an s substrate, a crystal of a II-VI compound semiconductor and a II-VI compound semiconductor device is grown by growing an n-type GaAs buffer layer on an n-type GaAs substrate. It can also improve the performance.

Further, in the first to third embodiments, the II-VI group compound semiconductor manufactured by the MBE method is used.
The present invention relates to other methods, such as metalorganic chemical vapor deposition (MOVP).
It can also be used for II-VI group compound semiconductors produced by E) and the like.

In the third embodiment, a GaAs substrate is used. However, by using a substrate made of a III-V compound semiconductor such as an InP substrate or a ZnSe substrate, or a II-VI compound semiconductor, a sufficient etching rate can be obtained. Ratio can be obtained.

In addition, various modifications can be made without departing from the gist of the present invention. (Embodiment 4) Next, an embodiment of the optical disk apparatus of the present invention will be described with reference to the drawings.

The specific structure of the optical disk device according to the present invention will be described with reference to the drawings. FIG. 7 shows a semiconductor laser according to the present invention applied to an optical disk device. Can-type semiconductor laser 701 with laser chip in can
A laser beam 702 having a wavelength of 510 nm is converted into a parallel beam by a collimator lens 703 and then split into three beams by a diffraction grating 704 (not shown).
05, and is condensed by the condensing lens 706.
A spot having a diameter of 700 nm is formed on the pattern No. 07. Disk 7
07 again passes through the condenser lens 706,
The light is reflected by the half prism 705, passes through a cylindrical lens 709 narrowed by a light receiving lens 708, enters a photodiode 710, and is converted into an electric signal.

At this time, the displacement of the optical disk 707 in the radial direction is detected by the divided three beams, and the displacement of the focal point is detected by the cylindrical lens 709. This shift is corrected by fine adjustment of the optical system by the drive system 711.

As described above, the II-VI compound semiconductor laser according to the present invention is applied to an optical disk apparatus having a condensing optical system for guiding laser light from a semiconductor laser to an optical disk and a photodetector for reading light reflected on the optical disk. If applied, high-density disk reading (reproduction) can be operated with high reliability. Furthermore, since high output of 15 mW or more is possible, writing (recording) on an optical disk is also possible, and an optical disk device having excellent characteristics with a simple configuration that can read and write with a single laser. Application of is also possible.

In this embodiment, a can-type semiconductor laser having a laser chip in a can is used. However, the optical disk apparatus of the present invention has a laser chip disposed on a silicon substrate, and a laser chip and an optical signal detection device. The size and thickness can be reduced by integrally forming a photodiode for use with a micromirror that reflects laser light from a laser chip.

[0086]

As described above, the present invention relates to a first semiconductor layer made of a II-VI compound semiconductor containing at least Te as a group VI element constituting a II-VI compound semiconductor, and the first semiconductor layer. A III-V group compound semiconductor provided on the layer or a second semiconductor layer comprising a II-VI group compound semiconductor containing no Te or containing Te but having a smaller Te composition than the first semiconductor layer. Further, by having a configuration in which the second semiconductor layer is provided with an opening partly reaching the first semiconductor layer, a highly accurate and low-damage element can be provided, which cannot be conventionally obtained. Semiconductor device having an improved structure can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a semiconductor laser device before selective etching according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the semiconductor laser device according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a semiconductor laser device before selective etching according to a second embodiment of the present invention;

FIG. 4 is a sectional view of a semiconductor laser device according to a second embodiment of the present invention;

FIG. 5 is a sectional view of a semiconductor laser device before selective etching according to a third embodiment of the present invention.

FIG. 6 is a sectional view of a semiconductor laser device according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram of an optical disc device according to a fourth embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 101 metal electrode 102 n-type GaAs substrate 103 n-type ZnSe layer 104 n-type ZnMgSSe cladding layer 105 ZnSe-based double hetero junction 105a n-type ZnSSe waveguide layer 105b ZnCdSe active layer 105cp p-type ZnSSe waveguide layer 106 p-type ZnMgSSe One cladding layer 107 ZnSSeTe etching stop layer 108 p-type ZnMgSSe second cladding layer 109 p-type ZnSSe cap layer 110 p-type ZnSe / ZnTe pseudo-graded contact layer 111 photoresist resist mask 201 metal electrode 202 n-type GaAs substrate 203 n-type ZnSe Layer 204 n-type ZnMgSSe cladding layer 205 ZnSe-based double heterojunction 205a n-type ZnSSe waveguide layer 205b ZnCdSe active layer 205cp p-type Zn SSe waveguide layer 206 p-type ZnMgSSe first cladding layer 207 ZnSSeTe etching stop layer 208 p-type ZnMgSSe second cladding layer 209 p-type ZnSSe cap layer 210 p-type ZnSe / ZnTe pseudo graded contact layer 211 metal electrode 212 current confinement layer 301 Metal electrode 302 n-type GaAs substrate 303 n-type ZnSe layer 304 n-type ZnMgSSe cladding layer 305 ZnSe-based double hetero junction 305 a n-type ZnSSe waveguide layer 305 b ZnCdSe active layer 305 c p-type ZnSSe waveguide layer 306 p-type ZnMgSSe first Cladding layer 307 ZnSSeTe etching stop layer 308 current confinement layer 309 photoresist resist mask 401 metal electrode 402 n-type GaAs substrate 403 n-type ZnSe layer 04 n-type ZnMgSSe cladding layer 405 ZnSe-based double hetero junction 405a n-type ZnSSe waveguide layer 405b ZnCdSe active layer 405c p-type ZnSSe waveguide layer 406 p-type ZnMgSSe first cladding layer 407 ZnSSeTe etching stop layer 408 current confinement layer 409 p-type ZnMgSSe second cladding layer 410 p-type ZnSSe cap layer 411 p-type ZnSe / ZnTe pseudo graded contact layer 412 metal electrode 501 n-type GaAs substrate 502 n-type ZnSSeTe etching stop layer 503 n-type ZnSe layer 504 n-type ZnMgSSe cladding layer 505 ZnSe-based double hetero junction 505a n-type ZnSSe waveguide layer 505b ZnCdSe active layer 505c p-type ZnSSe waveguide layer 506 p-type ZnMgS Se clad layer 507 p-type ZnSSe cap layer 508 p-type ZnSe / ZnTe pseudo graded contact layer 509 current confinement layer 510 SiO2 / TiO2 DBR reflector 511 metal electrode 601 n-type GaAs substrate 602 ZnSSeTe etching stop layer 603 n-type ZnSe layer 604 -Type ZnMgSSe cladding layer 605 ZnSe-based double hetero junction 605a n-type ZnSSe waveguide layer 605b ZnCdSe active layer 605c p-type ZnSSe waveguide layer 606 p-type ZnMgSSe cladding layer 607 p-type ZnSSe cap layer 608 p-type ZnSe / ZnTe pseudo gray Did contact layer 609 Current confinement layer 610 SiO ₂ / TiO ₂ DBR reflector 611 Metal electrode 612 SiO ₂ / TiO ₂ DBR reflector 613 Metal electrode 70 DESCRIPTION OF SYMBOLS 1 Semiconductor laser 702 Laser beam 703 Collimator lens 704 Diffraction grating 705 Half prism 706 Condensing lens 707 Optical disk 708 Light receiving lens 709 Cylindrical lens 710 Photodiode 711 Drive system

Claims (17)

[Claims] 1. A first semiconductor layer comprising a II-VI compound semiconductor containing at least Te as a Group VI element constituting a II-VI compound semiconductor, and a III-VI compound semiconductor provided on the first semiconductor layer. A second semiconductor layer made of a II-VI compound semiconductor that does not contain Te or contains Te or contains Te, but has a smaller Te composition than the first semiconductor layer;
A semiconductor element, wherein an opening reaching the first semiconductor layer is provided in a part of the semiconductor layer. 2. A first semiconductor layer comprising a II-VI compound semiconductor containing at least Te as a group VI element constituting a II-VI compound semiconductor is provided on a substrate, and the first semiconductor layer is formed from the substrate. A semiconductor element having an opening provided so as to remove a part of the substrate to a layer. 3. A double heterojunction having an active layer composed of a II-VI compound semiconductor and light guide layers provided above and below the active layer, and directly on the double heterojunction. Or an etching stop layer constituted by a first semiconductor layer made of a II-VI compound semiconductor containing at least Te as a group VI element constituting a II-VI compound semiconductor provided via a first cladding layer; A stripe formed by a second semiconductor layer made of a II-VI compound semiconductor, which does not contain Te or contains Te but has a smaller Te composition than the first semiconductor layer, provided on the etching stop layer; And a second cladding layer. 4. A double heterojunction having an active layer made of a II-VI compound semiconductor and light guide layers provided above and below said active layer, and directly on said double heterojunction. Or an etching stop layer constituted by a first semiconductor layer made of a II-VI compound semiconductor containing at least Te as a group VI element constituting a II-VI compound semiconductor provided via a first cladding layer;
Te is not contained or Te is contained, but compared to the first semiconductor layer,
A current confinement layer composed of a second semiconductor layer made of a II-VI compound semiconductor having a small composition and having a stripe-shaped opening, and a second cladding layer provided in the opening. Characteristic semiconductor light emitting device. 5. A surface-emitting type semiconductor light-emitting device provided on a substrate, wherein a light-emitting layer is made of a II-VI compound semiconductor, and a II-VI compound semiconductor is provided between the substrate and the light-emitting layer. II-VI containing at least Te as group VI element
A first semiconductor layer made of a group III compound semiconductor, and an opening provided so as to remove a part of the substrate from the substrate to the first semiconductor layer. Semiconductor light emitting device. 6. The semiconductor light emitting device according to claim 3, wherein the first semiconductor layer is removed from the opening. 7. A step of forming a first semiconductor layer made of a II-VI compound semiconductor containing at least Te as a group VI element constituting the II-VI compound semiconductor, and forming a first semiconductor layer on the first semiconductor layer. II-VI which does not contain or contains Te, or contains less Te than the first semiconductor layer.
Forming a second semiconductor layer made of a group III compound semiconductor; and selectively etching the second semiconductor layer using the first semiconductor layer as an etching stop layer. . 8. Constituting a II-VI compound semiconductor on a substrate
Forming a first semiconductor layer made of a II-VI compound semiconductor containing at least Te as a group VI element;
Selectively etching a region from said substrate to said first semiconductor layer using said semiconductor layer as an etching stop layer. 9. Constituting a group II-VI compound semiconductor on a substrate
Forming a first semiconductor layer made of a II-VI compound semiconductor containing at least Te as a group VI element; and II- containing no Te or containing Te but having a smaller Te composition than the first semiconductor layer. Selectively etching the first semiconductor layer while leaving the group VI compound semiconductor. 10. The composition ratio of Te in the first semiconductor layer is 0.1 ≦ x.
The method according to any one of claims 7 to 9, wherein? 11. The second semiconductor layer is made of a II-VI group compound semiconductor, and the Te composition y of the second semiconductor layer is 0 ≦ y ≦
0.8, and the Te composition x of the first semiconductor layer is 0.1 ≦ x ≦ 1
8. The method according to claim 7, wherein y ≦ x−0.1 is satisfied. 12. The semiconductor device according to claim 7, wherein the first semiconductor layer has a composition that lattice-matches with a crystal lattice of a substrate on which the first semiconductor layer is formed. Manufacturing method. 13. The first semiconductor layer has a thickness of 1 nm to 50 nm.
The method for manufacturing a semiconductor device according to claim 7, wherein the range is 0 nm. 14. The method according to claim 7, wherein etching is performed using a neutral or alkaline solution containing at least hydrogen peroxide as an etching solution. 15. The method according to claim 9, wherein etching is performed using an acidic solution containing at least dichromate ions or permanganate ions as an etchant. 16. The semiconductor device according to claim 1, wherein the semiconductor device is a semiconductor laser using a II-VI compound semiconductor, and a laser beam emitted from the semiconductor laser is focused on a recording medium. An optical disc device comprising: an optical system; and a photodetector that receives reflected light from the recording medium. 17. The optical disk device according to claim 16, wherein information is read from or written to a recording medium by a laser.