JPH08340130A - Compound semiconductor device and method of manufacturing the same - Google Patents

Abstract

PURPOSE: To improve the productivity while forming a flat semiconductor film in relation to the title compound semiconductor device including wultzite structure compound semiconductors. CONSTITUTION: The title compound semiconductor device is composed of a semiconductor substrate 11 in cubic system crystalline structure, a cubic system semiconductor layer 12 formed on a main surface of the semiconductor substrate 11 and wultzite structure crystalline semiconductors 13-16 in the same group as that of the cubic system semiconductor layer 12 formed on said layer 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound semiconductor device and a method of manufacturing the same, and more particularly to a compound semiconductor device including a compound semiconductor having a wurtzite structure and a method of manufacturing the same.

[0002]

2. Description of the Related Art A light emitting diode using a wurtzite type compound semiconductor containing GaN as a light emitting layer (active layer) has, for example, a structure as shown in FIG. It is in the range of 500 nm. In FIG. 3 (a), on the α-crystal sapphire (α-Al ₂ O ₃ ) substrate 1, a GaN buffer layer 2, an n-type GaN clad layer 3, and an undoped InGaN active layer are formed by using a metal organic growth (MOVPE) method. The layer 4 and the p-type GaN cladding layer 5 are formed in this order. In addition, on the p-type GaN cladding layer 5, a p-side electrode 6 and an n-type Ga are formed.
An n-side electrode 7 is formed on the exposed portion of the N cladding layer 3.

The cavity facet of this light emitting diode is formed by cutting the sapphire substrate 1 on which each compound semiconductor layer has been grown to a desired size.

[0004]

By the way, since the sapphire substrate 1 is an insulator, when the n-side electrode 7 is connected to the n-type GaN clad layer 3, the p-type GaN clad layer 5 is partially formed.
Since the n-type GaN clad layer 3 is exposed by etching from to the upper part of the n-type GaN clad layer 3, there is a problem that the productivity cannot be sufficiently enhanced.

On the other hand, in some cases, a silicon substrate containing impurities to impart conductivity is used instead of the sapphire substrate 1, and a compound semiconductor layer is crystal-grown on the (111) plane of the silicon substrate. . The (111) plane corresponds to the (0001) plane of the wurtzite structure.
However, a silicon substrate having a (111) main surface cannot be cleaved in a direction perpendicular to the main surface, and thus a step of forming a resonator surface by scribe or dicing is required, which is troublesome.

Further, as shown in FIG.
When GaN is grown on the silicon substrate 8 at a low temperature of about 00 ° C., there is a problem that the GaN 9 grows granularly and a flat film cannot be obtained. Further, the sapphire substrate 1 does not have the cleavage property unlike a GaAs substrate or an InP substrate, and a method of forming a resonator surface by dicing or scribing is adopted. Moreover, since the sapphire substrate 1 itself is extremely hard, Dicing and scribing can be performed only after thinning by polishing, which further reduces the throughput.

The present invention has been made in view of the above problems, and an object thereof is to provide a compound semiconductor device capable of improving productivity and obtaining a flat semiconductor film, and a manufacturing method thereof. To do.

[0008]

[Means for Solving the Problems]
As illustrated in (c), a semiconductor substrate 11 having a cubic crystal structure, a wurtzite crystal semiconductor layer 13 to 16 formed above the main surface of the semiconductor substrate 11, and the semiconductor substrate. 11. A compound, which is formed between the main surface of the wurtzite-type crystal-based semiconductor layer 13 and the wurtzite-type crystal-based semiconductor layer 13 and has a cubic semiconductor layer 12 of the same compound group as the wurtzite-type crystal-based semiconductor layer 13. The solution is a semiconductor device.

Alternatively, a plane perpendicular to the (111) plane or (1
11) A semiconductor substrate 11 whose main surface is a surface perpendicular to a surface equivalent to the surface and which has a cubic crystal structure, and a wurtzite crystal semiconductor formed above the main surface of the semiconductor substrate 11. And a compound semiconductor device characterized by having an active layer 15 of. In this case, a cubic semiconductor layer 13 is formed between the surface of the main surface and the wurtzite crystal semiconductor.

The cubic semiconductor layer 13 is made of Al _Z Ga _1-Z.
It is characterized in that it is a P layer (0 ≦ Z ≦ 1). The semiconductor substrate 11 is made of silicon or germanium. The wurtzite crystalline semiconductor layers 13 and 16
Is an Al _W Ga _1-W N layer (0 ≦ W ≦ 1) or Al _X Ga _1-XY In
_Y N layer (0 ≦ X ≦ 1, 0 ≦ Y ≦ 1, 0 ≦ 1-X−Y ≦
It is characterized in that it is 1).

Alternatively, as illustrated in FIGS. 1 and 2, a step of growing a cubic semiconductor layer 12 on a main surface of a semiconductor substrate 11 having a cubic crystal structure, and the cubic semiconductor layer 12 Forming a buffer layer 13 on the above at a low temperature; heating the buffer layer 13 to crystallize;
And a step of forming wurtzite type crystal-based semiconductor layers 14 to 16 on the crystallized buffer layer 13 at a high temperature.

Alternatively, the main surface of the semiconductor substrate 11 is a surface perpendicular to the (111) surface or a surface equivalent to the (111) surface, and the wurtzite crystal-based semiconductor layer 1
This is solved by a method for manufacturing a compound semiconductor device, which comprises cleaving the semiconductor substrate to (111) plane or a plane equivalent to the (111) plane after forming 4 to 16.

[0013]

[Operation] According to the present invention, a cubic compound semiconductor layer is formed on a main surface of a semiconductor substrate whose crystal structure belongs to the cubic system, and a wurtzite crystal compound is formed on the cubic semiconductor layer. A semiconductor layer is formed. If the crystal of the semiconductor substrate contains impurities, the resistance of the semiconductor substrate is lowered. Therefore, a current can flow through the wurtzite crystal compound semiconductor layer on the semiconductor substrate through the semiconductor substrate containing the impurities. Therefore, it is not necessary to etch the semiconductor layer to connect the electrodes, and the throughput is improved.

Further, it is easy to flatly form the same cubic compound semiconductor layer on the semiconductor substrate, and depending on the polarity of the compound semiconductor, a wurtzite crystal semiconductor layer of the same group can be formed thereon. Further, since it is possible to form a semiconductor laser or the like on a cubic semiconductor substrate such as silicon, it is possible to form a silicon active element on the same substrate in a separate process And the optical device can be highly integrated.

Further, according to the present invention, cleavage is easy (1
11) Since a cubic semiconductor substrate having a plane perpendicular to the plane or an equivalent plane as a main surface is used and a compound semiconductor layer such as an intermediate layer and a buffer layer is formed thereon, When the semiconductor substrate is cleaved in the vertical direction after the compound semiconductor layer is formed, the compound semiconductor layers are also cleaved at the same time, whereby the resonance surface of the light emitting diode formed on the semiconductor substrate can be easily obtained, and Easy to split.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are cross-sectional views showing a manufacturing process of a light emitting diode according to a first embodiment of the present invention. In this embodiment, as shown in FIG. 1A, an n-type silicon substrate 11 is used as a substrate forming a semiconductor laser, and (11
1) The main surface is a surface perpendicular to the surface or an equivalent surface.

A plane equivalent to the (111) plane is (11
There are (1) plane, (11-1) plane, (1-11) plane, and the plane perpendicular to the plane equivalent to (111) plane is (1-
10) plane, (211) plane, (2-1-1) plane and the like. In the index indicating the crystal plane, "-1" indicates 1 with a negative sign on the head, that is, "1 bar". Then, as a pretreatment for growing a compound semiconductor layer on the main surface of the silicon substrate 11, the main surface of the silicon substrate 11 is organically cleaned, and the main surface is further cleaned using a hydrofluoric acid-based etching solution.

Next, the silicon substrate 11 is placed in a reaction furnace (not shown), and the surface thereof is placed in a hydrogen atmosphere at 1100 ° C.
Heat for 0 minutes to remove the native oxide film. After that, as shown in FIG. 1 (b), on the main surface of the silicon substrate 11, a cubic crystal having a lattice constant close to that of silicon and the same cubic II
I-V group compound semiconductor intermediate layer, for example, n-type Al _z Ga _1-z P
The intermediate layer 12 is formed to a thickness of 100 nm (0 ≦ Z ≦
1). The n-type Al _z Ga _1-z P intermediate layer 12 has an electric dipole (polarity).

Since the Al _z Ga _1-z P intermediate layer 12 has polarity and the same III-V group element is easily attached to the surface of the Al _z Ga _1-z P intermediate layer 12, Al _w Ga _1-w N of 500 to 600 is deposited thereon. When grown to a thickness of 30 nm at a low temperature of ℃, a flat Al _w Ga _1-w N buffer layer 13 was formed.
Are formed to have a substantially uniform thickness. Subsequently, as shown in FIG. 1D, the Al _w Ga _1-w N buffer layer 13 is crystallized at a high temperature of 1000 to 1100 ° C., and the upper surface thereof is made to have a wurtzite crystal structure.

After that, as shown in FIG. 2 (a), Al _w Ga
_An n-type Al _x Ga _1-xy In _y N clad layer 14 having a thickness of 2 μm is formed on the _1-w N buffer layer 13 at a temperature of 1000 to 1100 ° C.
m, an undoped GaN active layer (active layer) 15 of 50 nm,
The p-type Al _x Ga _1-xy In _y N cladding layer 16 is formed in order with a thickness of 500 nm (0 ≦ W ≦ 1, 0 ≦ X ≦ 1, 0 ≦ Y
≦ 1, 0 ≦ 1−X−Y ≦ 1).

On the crystallized Al _w Ga _1-w N buffer layer 13, the formation of growth nuclei is promoted, so that the two-dimensional growth is facilitated and the flat Al _x Ga _1-xy In _y N cladding layer is formed. 14,
16 and the GaN active layer 15 are obtained. The compound semiconductor layer on the silicon substrate 11 as described above is formed by, for example, a metal organic chemical vapor deposition (MOVPE) method. Al _z Ga _1-z P intermediate layer 12 and Al _w Ga _1-w N buffer layer 13 grown at low temperature, Al _x Ga _1-xy In _y N clad layers 14 and 16 grown at high temperature, and GaN activity Table 1 shows an example of the conditions of the growth temperature, the growth raw material, and the raw material gas flow rate for each of the layers 15.
become that way. The gases shown in Table 1 are introduced into the reaction furnace together with a carrier gas (for example, hydrogen gas), and the pressure in the reaction furnace during growth is adjusted to 200 Torr. The cladding layer 14 may be Al _x Ga _1-x N.

[0022]

[Table 1]

After the growth of each of the compound semiconductor layers described above is completed, an insulating film (not shown) is formed on the p-type Al _x Ga _1-xy In _y N cladding layer 16, and an opening is formed in the insulating film. After forming (not shown), a p-side electrode 17 is formed on the insulating film and in the opening as shown in FIG. 2 (b). Further, the n-side electrode 18 is formed on the bottom surface of the silicon substrate 11. After this,
As shown in FIG. 2 (c), when cleaving on the (111) plane perpendicular to the main surface of the silicon substrate 11 or a plane equivalent thereto,
Cleavage planes are also obtained in the silicon substrate 11 and the Al _x Ga _1-xy In _y N clad layer 14, the GaN active layer 15, and the Al _x Ga _1-xy In _y N clad layer 16 on the silicon substrate 11 and thereby the resonator surface. Is secured.

As described above, the silicon substrate 11 whose main surface is the (111) plane which is easy to cleave or the plane perpendicular to the plane equivalent thereto is used, and the intermediate layer 12, the buffer layer 13 and the like are formed thereon. Since the compound semiconductor layers are formed, if the silicon substrate 11 is cleaved in the direction perpendicular to the main surface after the compound semiconductor layers are formed, those compound semiconductor layers are also cleaved at the same time, and the resonance plane is easily formed. can get.

Moreover, since the silicon substrate 11 is made low in resistance by containing impurities, the silicon substrate 11 which conducts to the n-type Al _x Ga _1-xy In _y N clad layer 14 without etching the compound semiconductor layer. Electrode 1 on the bottom
Forming 8 facilitates electrical connection between the electrode 18 and the n-type Al _x Ga _1-xy In _y N cladding layer 14, thereby improving throughput.

On the silicon substrate 11, a cubic Al _z Ga _1-z P intermediate layer 12 having the same crystal structure as that of silicon is formed into a flat film, and Al _w Ga is formed on the intermediate layer 12 depending on its polarity.
_{The 1-w} N buffer layer 13 is formed into a flat film, and the buffer layer 13 is crystallized into a wurtzite structure at high temperature, and then the wurtzite cladding layers 14 and 16 and the active layer 15 are formed. ing.

Further, since a semiconductor laser can be formed on the silicon substrate 11, it becomes possible to form a silicon active element on the same substrate in a separate process, and a semiconductor integrated circuit and a semiconductor laser can be integrated. In the above-described embodiment, the main surface of the silicon substrate 11 is the (111) surface or a surface perpendicular to the surface equivalent to the (111) surface.
1) The surface or a surface equivalent thereto may be the main surface. In this case, it is not possible to cleave in the direction perpendicular to the main surface of the silicon substrate, but it is easy to connect the electrodes, integrate the silicon active element and the semiconductor laser, or wurtzite type on the silicon substrate. It is possible to form a flat compound semiconductor layer.

Although the n-type silicon substrate is used in the above embodiment, a p-type silicon substrate is formed,
The impurity introduction may be adjusted so that the p-type and n-type of the compound semiconductor layer thereabove are opposite. Further, in the above-described embodiment, the light emitting diode is described as an example, but it may be applied to other electronic devices.

Further, although the silicon substrate is used in the above description, a cubic substrate such as germanium may be applied instead of the silicon substrate.

[0030]

As described above, according to the present invention, a cubic compound semiconductor layer is formed on the main surface of a semiconductor substrate whose crystal structure belongs to the cubic system, and the cubic compound semiconductor layer is formed on the cubic semiconductor layer. Since the wurtzite crystal compound semiconductor layer is formed, it is possible to reduce the resistance of the semiconductor substrate by containing impurities.Therefore, by forming an electrode on the semiconductor substrate, a current is supplied to the wurtzite crystal compound semiconductor layer. Can be drained,
The electrodes can be easily connected to improve the throughput.

Further, it is easy to flatly form the same cubic compound semiconductor layer on the semiconductor substrate, and depending on the polarity of the compound semiconductor, a wurtzite crystal semiconductor of the same group may be further formed thereon. The layer can be formed flat.
Furthermore, since a semiconductor laser or the like is formed on a cubic semiconductor substrate made of silicon or the like, it becomes possible to form a silicon active element on the same substrate in a separate process, and electronic devices and optical devices are highly integrated. be able to.

Further, according to the present invention, cleavage is easy (1
11) Since a cubic semiconductor substrate having a plane perpendicular to the plane or an equivalent plane as a main surface is used and a compound semiconductor layer such as an intermediate layer and a buffer layer is formed thereon, When the semiconductor substrate is cleaved in the vertical direction after forming the compound semiconductor layer of, the compound semiconductor layers are also cleaved at the same time, and the resonance surface of the light emitting diode formed on the semiconductor substrate can be easily obtained, and the substrate division can be performed. It will be easier.

[Brief description of drawings]

FIG. 1 is a cross-sectional view (1) showing a manufacturing process of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view (2) showing the manufacturing process of the semiconductor device according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a conventional semiconductor device.

[Explanation of symbols]

11 silicon substrate (cubic semiconductor substrate) 12 Al _z Ga _1-z P intermediate layer 13 Al _w Ga _1-w N buffer layer 14 Al _x Ga _1-xy In _y N clad layer 15 GaN active layer (active layer) 16 Al _x Ga _1-xy In _y N Cladding layer 17 p-side electrode 18 n-side electrode

Claims (8)

[Claims] 1. A semiconductor substrate having a cubic crystal structure, a wurtzite crystal-based semiconductor layer formed above a main surface of the semiconductor substrate, a main surface of the semiconductor substrate, and the wurtzite crystal. And a cubic semiconductor layer of the same compound group as that of the wurtzite type crystal semiconductor layer formed between the wurtzite type crystal semiconductor layer and the wurtzite type crystal semiconductor layer. 2. A semiconductor substrate having a principal plane that is a plane perpendicular to the (111) plane or a plane equivalent to the (111) plane and having a cubic crystal structure. A compound semiconductor device, comprising: an active layer made of a wurtzite type crystal semiconductor formed above the surface. 3. The compound semiconductor device according to claim 2, wherein a cubic semiconductor layer is formed between the surface of the main surface and the wurtzite crystal semiconductor. 4. The cubic semiconductor layer is an Al _Z Ga _{1 -Z} P layer (0≤Z≤1).
The compound semiconductor device described. 5. The compound semiconductor device according to claim 1, wherein the semiconductor substrate is made of silicon or germanium. 6. The wurtzite crystal semiconductor layer is Al _W Ga
_1-W N layer (0 ≦ W ≦ 1) or Al _X Ga _1-XY In _Y N layer (0
≦ X ≦ 1, 0 ≦ Y ≦ 1, 0 ≦ 1−X−Y ≦ 1), The compound semiconductor device according to claim 1 or 2. 7. A step of growing a cubic semiconductor layer on a main surface of a semiconductor substrate whose crystal structure belongs to the cubic system, a step of forming a buffer layer on the cubic semiconductor layer at a low temperature, A method of manufacturing a compound semiconductor device, comprising: a step of heating a buffer layer for crystallization; and a step of forming a wurtzite crystal semiconductor layer on the crystallized buffer layer at a high temperature. 8. The main surface of the semiconductor substrate is (111)
A plane perpendicular to the plane or a plane equivalent to the (111) plane, which is the plane equivalent to the (111) plane or the (111) plane after the wurtzite crystal semiconductor layer is formed. The method of manufacturing a compound semiconductor device according to claim 7, wherein the cleavage is performed.