JP3215504B2 - Method for manufacturing semiconductor light emitting device and semiconductor light emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wet etching method for compound semiconductors.

[0002]

2. Description of the Related Art As a processing technique of a semiconductor crystal, there is wet etching in which a crystal is immersed in a corrosive liquid (etching liquid) to perform etching. In this method,
By applying a resist resistant to an etchant on the semiconductor surface, forming a resist pattern by partially removing the resist by a method of photolithography or electron beam lithography, and immersing the semiconductor crystal in the etchant, A method of performing etching while leaving only a necessary portion of a semiconductor crystal has been applied to formation of a semiconductor element structure.

[0003] Compared with other etching techniques, the wet etching technique has features that the equipment is simpler and damage to a semiconductor crystal is small, so that defects in the crystal greatly affect the element characteristics, especially in a semiconductor light emitting element. Is often used to give.

[0004]

However, wet etching has the following problems. That is, because the adhesion between the resist used as the mask and the underlying crystal is poor,
The etchant penetrates between the two layers, causing side etching. In addition, since it is difficult to strictly control the adhesion, the controllability of the amount of side etching is poor, and the variation in processing dimensions is large. Therefore, there has been a problem that the characteristics of the semiconductor device formed by the wet etching method are not constant, and the production yield is poor.

For this reason, a method of forming a thin film of a dielectric material such as SiNx by a CVD method or the like and using it as a mask with improved adhesion to the underlying crystal has been performed, but this method requires a complicated device manufacturing process. In addition, there is a problem that undesired distortion or damage is given to the underlying crystal.

In order to solve the conventional problem of adhesion, a method of using an epitaxially grown thin film as a mask layer in a semiconductor crystal such as an AlGaAs crystal utilizing the fact that the etching rate varies depending on the mixed crystal composition ratio. Is used. For example, FIG. 4 shows a sectional view of a conventional example. Figure 4 Al epitaxially grown and formed on the GaAs substrate 1 as shown in (a) _{0. 1} Ga ₀ to. ₉ Asll surface, as a mask _{layer, Al 0. 6 Ga 0.} 4 As the thin-film crystal 1
2 was epitaxially grown and formed, after the resist pattern formation, Al ₀ by hydrofluoric acid as shown in FIG. 4 (b). ₆ G
a _{0. 4} As removing a portion of the mask layer 12 crystals.

[0007] Subsequently, as shown in FIG. 4 (c), Al _0.
6 Ga _{0. 4,} As the mask layer 12 is used as _{Al 0. 1 Ga 0. 9} As the etching mask of the _{crystal, Al 0. 6 Ga 0.} 4 Ammonia use of the formulations does not corrode the As, hydrogen peroxide, water Al ₀ with a mixed solution of. only ₁ Ga _{0 ·} 9 as crystal 12 is selectively etched. Al 0 _{· 6} used as the etching mask
Ga 0 _{· 4} As crystal, Al _{0. 1} Ga _0. Because it was epitaxially grown and formed on the ₉ As crystal as a base, adhesion between the base is very good.

However, in this case, Al _{0, 6} Ga ₀ used as the mask layer. ₄ mole fraction of As crystal tends surface is oxidized for large as 0.6, the adhesion of the resist is poor, the resist Etching cannot be performed according to pattern. As described above, when the epitaxial growth thin film is used as a mask by utilizing the difference in the etching rate due to the difference in the mixed crystal ratio, it is necessary to increase the difference in the mixed crystal ratio between the base crystal to be etched and the crystal used as the etching mask. In particular, the degree of structural freedom is limited when the underlying crystal is desired to have a multilayer structure.

In addition, since there is a problem of oxidation of the crystal surface as described above, it is not suitable for fabricating an actual element structure.

The present invention has been made to solve the above problems, and has as its object to etch an AlGaAs semiconductor crystal according to a resist pattern.

[0011]

According to the present invention, there is provided a method for manufacturing a semiconductor light emitting device, comprising the steps of:
Directly epitaxially growing a second semiconductor crystal made of GaInAsP having a composition lattice-matched to the first semiconductor crystal on the surface of the semiconductor crystal, and selecting the first semiconductor crystal using the second semiconductor crystal as a mask And a step of selectively etching. At this time, the second semiconductor crystal preferably has a layer thickness of 100 nm or less. The method for manufacturing a semiconductor light emitting device according to the present invention is a method of manufacturing a semiconductor light emitting device comprising: A step of directly epitaxially growing a crystal, a step of selectively etching the first semiconductor crystal using the second semiconductor crystal as a mask, and a step of growing a third semiconductor crystal after removing the second semiconductor crystal And a step of causing At this time, the second semiconductor crystal preferably has a layer thickness of 100 nm or less. The method for manufacturing a semiconductor light emitting device according to the present invention is a method of manufacturing a semiconductor light emitting device comprising: A step of directly epitaxially growing a crystal, a step of selectively etching the first semiconductor crystal using the second semiconductor crystal as a mask, and a step of subsequently growing a third semiconductor crystal. It is characterized by the following. At this time, the second semiconductor crystal has a layer thickness of 100
nm or less. A semiconductor light emitting device according to the present invention includes a first semiconductor crystal made of AlxGa1-xAs (0 ≦ x ≦ 1) and a GaInAsP having a composition epitaxially grown on the surface of the first semiconductor crystal and lattice-matched to the first semiconductor crystal. A second semiconductor crystal, selectively removed, comprising:
A third semiconductor crystal grown on the first semiconductor crystal, wherein the first semiconductor crystal has a region in which the pattern of the second semiconductor crystal is transferred and selectively removed, Characterized in that the third semiconductor crystal is grown also in the region which has been removed. At this time, the second semiconductor crystal preferably has a layer thickness of 100 nm or less.

[0012]

The GaInAsP thin film crystal mask of the present invention is manufactured by an epitaxial growth method so as to be lattice-matched to the underlying AlGaAs semiconductor crystal, so that the adhesion is improved without causing unnecessary distortion or damage which adversely affects the characteristics of the device. I do.

Further, since it is made of a material different from that of the base crystal, the etching selectivity is large, the degree of freedom of the element structure is high, and wet etching excellent in controllability of processing is enabled.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a wet etching method according to the present invention will be described in detail with reference to embodiments.

FIG. 1 is a sectional view showing an etching method according to a first embodiment of the present invention. First, as shown in FIG. 1A, a GaInAsP thin film crystal having a composition lattice-matched to the AlGaAs crystal is formed on an AlGaAs layer 2 formed by epitaxial crystal growth on the surface of a GaAs substrate 1.
As epitaxial growth. Here, GaIn
It is desirable that the thickness of the AsP thin film crystal 3 be 100 nm or less in order to suppress side etching. GaIn
Since the AsP crystal is lattice-matched to the AlGaAs crystal, the GaInAsP mask layer 3 can be formed without causing unnecessary distortion inside the AlGaAs layer 2. Subsequently, a resist 4 having a pattern formed on the surface of the GaInAsP mask layer 3 by a photolithography method or an electron beam lithography method is manufactured.

Next, as shown in FIG.
The GaInAsP mask layer 3 is removed according to the resist pattern using a solution that corrodes AsP crystals, for example, a mixed solution of saturated bromic acid: phosphoric acid: water = 2: 1: 15.
At this time, since the GaInAsP mask layer 3 is sufficiently thin,
Lateral etching can be neglected. Therefore, the resist pattern can be faithfully transferred to the GaInAsP mask layer 3.

Thereafter, as shown in FIG.
A groove is formed inside the AlGaAs layer 2 by a wet etching method using a solution that corrodes only the lGaAs crystal, for example, a mixed solution of sulfuric acid: hydrogen peroxide: water = 1: 2: 20. The GaInAsP mask layer 3 is made of AlG
Since it is formed by epitaxial growth on the aAs layer 2 so as to be lattice-matched, the adhesion to the base is extremely good, and the etchant does not flow under the mask layer. Further, since an etching solution that does not corrode the GaInAsP crystal is used, AlGa is used without side etching.
A groove can be formed inside the As layer 2. Therefore, a groove having the same width as the resist pattern is formed in AlGa.
It can be formed inside the As layer 2.

FIG. 2 is a sectional view of an internal stripe type semiconductor laser according to a second embodiment of the present invention. The semiconductor laser shown in FIG. 2 has a first cladding layer 5 (X5) having a first conductivity type and an active layer 6 each made of AlGaAs crystal on a surface of a GaAs substrate 1 having a first conductivity type.
(X6), the second cladding layer 7 (X
7), a current blocking layer 8 (X8) having the first conductivity type,
A third cladding layer 9 (X9) having a conductivity type of
Of the contact layer 10 having the above-mentioned conductivity type.
Here, the values in parentheses are numerical values from 0 to 1 indicating the AlAs mole fraction of the AlGaAs crystal, and X6 <X5, X6 <
The relational expressions of X7, X8 ≦ X6 and X6 <X9 are satisfied.

Next, a method of forming the semiconductor laser structure shown in FIG. 2 will be described. The first cladding layer 5 to the current blocking layer 8 are formed on the surface of the GaAs substrate 1 by epitaxial growth, and then a GaInAsP mask layer (not shown) is formed by epitaxial growth. Next, a stripe groove is formed inside the current blocking layer 8 in the same manner as in the first embodiment, and GaInA is formed.
After removing the sP mask layer, a third cladding layer and a contact layer 10 are formed by growth.

In this embodiment, GaInA lattice-matched to the underlying AlGaAs crystal is used to form the internal stripe structure.
Since the sP thin film crystal is used as an etching mask, a semiconductor laser having a uniform stripe width can be easily manufactured without causing unnecessary distortion or damage inside the laser. In this embodiment, the GaInAsP mask layer is removed after forming the stripe groove, but may be buried inside the semiconductor laser without removing it.

FIG. 3 is a sectional view of an internal stripe type semiconductor laser according to a third embodiment of the present invention. The laser shown in FIG. 3 includes a current blocking layer 8 (X8) having a second conductivity type, each of which is made of an AlGaAs crystal, on a surface of a GaAs substrate 1 having a first conductivity type. The first clad layer 5 (X5), the active layer 6 (X6), and the second
A second cladding layer 7 (X7) having a conductivity type of
A contact layer 10 having a conductivity type of
The relational expressions of X6 <X5, X6 <X7, X8 ≦ X6 are satisfied. The method of creating this structure is the same as in the second embodiment.
In the second and third embodiments, Ga as an etching mask is used.
The InAsP mask may be removed but left as it is.

[0022]

According to the present invention, use of a GaInAsP crystal thin film having a composition lattice-matched to the AlGaAs crystal grown on the surface of the AlGaAs semiconductor crystal as a mask performs wet etching, thereby causing unnecessary strain inside the AlGaAs crystal. The AlGaAs crystal can be easily processed with good accuracy without causing any damage.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an etching step for explaining a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of an internal stripe type semiconductor laser for explaining a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of an internal stripe type semiconductor laser for explaining a third embodiment of the present invention.

FIG. 4 is a cross-sectional view showing an etching step for explaining a conventional example.

[Explanation of symbols]

1 GaAs substrate 2 AlGaAs crystal 3 GaInAsP mask layer 4 a resist 5 first cladding layer 6 active layer 7 second cladding layer 8 current blocking layer 9 third clad layer 10 contact layer _{11 Al 0 · 1 Ga 0.} 9 As layers 12 Al _{0 ·} 6 Ga _{0. 4} As mask layer

Continuation of the front page (56) References JP-A-3-252029 (JP, A) JP-A-61-59736 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21 / 306,21 / 308 H01S 5/00-5/30

Claims (6)

(57) [Claims] 1. A first method comprising AlxGa1-xAs (0 ≦ x ≦ 1).
Directly epitaxially growing a second semiconductor crystal made of GaInAsP having a composition lattice-matched to the first semiconductor crystal on the surface of the semiconductor crystal, and selecting the first semiconductor crystal using the second semiconductor crystal as a mask A method of manufacturing a semiconductor light emitting device, comprising: a step of selectively etching. 2. A first method comprising AlxGa1-xAs (0 ≦ x ≦ 1).
Directly epitaxially growing a second semiconductor crystal made of GaInAsP having a composition lattice-matched to the first semiconductor crystal on the surface of the semiconductor crystal, and selecting the first semiconductor crystal using the second semiconductor crystal as a mask A method of manufacturing a semiconductor light-emitting device, comprising: a step of selectively etching; and a step of growing a third semiconductor crystal after removing the second semiconductor crystal. 3. A first layer made of AlxGa1-xAs (0 ≦ x ≦ 1).
Directly epitaxially growing a second semiconductor crystal made of GaInAsP having a composition lattice-matched to the first semiconductor crystal on the surface of the semiconductor crystal, and selecting the first semiconductor crystal using the second semiconductor crystal as a mask A method of manufacturing a semiconductor light emitting device, comprising: a step of selectively etching; and a step of subsequently growing a third semiconductor crystal. 4. The second semiconductor crystal has a layer thickness of 100
The method of manufacturing a semiconductor light emitting device according to any one of claims 1 to 3, characterized in that nm or less. 5. A first layer made of AlxGa1-xAs (0 ≦ x ≦ 1).
And a G having a composition that is epitaxially grown on the surface of the first semiconductor crystal and lattice-matched to the first semiconductor crystal.
aInAsP, comprising a second semiconductor crystal selectively removed, and a third semiconductor crystal grown on the second semiconductor crystal, wherein the first semiconductor crystal, the second semiconductor crystal A semiconductor light emitting device having a region in which a pattern of a semiconductor crystal is transferred and selectively removed, and wherein the third semiconductor crystal is also grown in the selectively removed region. 6. The second semiconductor crystal has a layer thickness of 100
6. The semiconductor light emitting device according to claim 5 , wherein the diameter is equal to or less than nm.