JPH05218495A - Manufacture of semiconductor light emitting element - Google Patents

Abstract

PURPOSE:To enhance a semiconductor light emitting element in light emission characteristics by a method wherein a belt-shaped silicon oxide or silicon nitride surrounded with sides is provided onto a silicon board, a projection is provided to the side of the belt-shaped silicon oxide protruding toward the opposite side, and semiconductor crystal layers are formed and separated into islands for the formation of light emitting elements. CONSTITUTION:A part of a silicon oxide film 7 formed on the surface of a silicon board 1 is removed by etching. The silicon oxide film 7 is belt-shaped and surrounded with sides 7a, 7b, 7c, and 7d, and projections 10 are provided to the side 7b protruding toward the opposed side 7d. The belt-shaped silicon oxide film 7 is provided to the periphery of a region where a light emitting element 6 is formed. When a gallium arsenide single crystal layer 2 is grown, cracks are generated along lines which connect the projections 10 together starting from the projections 10 as starting points. The cracks relax an inner stress generated inside the semiconductor crystal layer 2 to protect the other part against cracks.

Description

Detailed Description of the Invention

[0001]

The present invention relates to LE on a silicon substrate.
The present invention relates to a method for manufacturing a semiconductor light emitting device including a D (light emitting device) array.

[0002]

2. Description of the Related Art For example, it has been proposed to use a light emitting element as a light source for a photosensitive drum of a page printer.

Silicon (Si) is suitable as a substrate for such a light emitting device in terms of strength, thermal conductivity and cost. Further, as a light emitting element, a compound semiconductor such as gallium arsenide (GaAs) or aluminum gallium arsenide (AlGaAs), which has good light emission characteristics and high electron mobility, is suitable. In order to form such a semiconductor layer on a silicon substrate, metal organic vapor phase epitaxy (MOCV) is used.
D) or molecular beam epitaxy (MBE) is suitable for epitaxial growth of a semiconductor crystal on a silicon substrate to form a plurality of light emitting devices on this epitaxial layer from the viewpoint of mass productivity.

As a method of forming a light emitting device composed of a compound semiconductor layer on a silicon substrate, a compound semiconductor crystal is epitaxially grown on one main surface of a silicon substrate, and unnecessary portions of the epitaxial layer are removed by photolithography or the like. Although a light emitting device is formed, since the gallium arsenide and the like have a different thermal expansion coefficient from that of silicon, when the semiconductor crystals are epitaxially grown on the entire surface of the silicon substrate at a high temperature inside the reactor, the temperature of the substrate is lowered. There is a problem in that when a light emitting element is formed, a current leaks when the semiconductor crystal layer is warped or cracked. That is, when a gallium arsenide layer is formed on a silicon substrate, a tensile stress of about 10 ⁹ dyne / cm ² is generated, and a thickness of 2
When a gallium arsenide layer of μm (2 × 10 ⁻⁴ cm) is deposited, 10 ⁹ d is formed on the silicon substrate and the gallium arsenide layer.
yne / cm ² × (2 × 10 ⁻⁴ cm) = 2 × 10 ⁵ dy
There is an absolute stress (total stress) of ne / cm, which causes a problem that a thin gallium arsenide layer is cracked and that the life of the light emitting element is shortened due to internal stress.

In order to solve such a problem, most of the surface of the silicon substrate is covered with, for example, a silicon oxide film, and only a region for forming a light emitting element is exposed to form this light emitting element. Although it may be possible to epitaxially grow the semiconductor crystal layer only in the region, if the semiconductor crystal layer is grown only in each region where the light emitting element is formed from the beginning, the crystallinity deteriorates due to the shape dependency of the semiconductor crystal. Will end up. That is, since the stress state at the edge portion of the semiconductor crystal layer is different from that at the central portion, if a large number of semiconductor crystal layers are formed in the individual regions from the beginning, the stress state becomes non-uniform and crystallinity,
In particular, the crystallinity of the outer peripheral portion of the selected region deteriorates, and the light emitting characteristics of the light emitting element deteriorate.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is characterized in that an edge made of silicon oxide or silicon nitride is formed on a silicon substrate. Forming an enclosed band-like portion, and providing a semiconductor crystal layer on the silicon substrate by providing a protrusion on the side of the band-like portion, the protrusion protruding toward the opposite side, and forming a semiconductor crystal layer in the band-like portion. The point is that a plurality of island-shaped light emitting elements are formed.

[0007]

With the above structure, the semiconductor crystal layer is cracked starting from the protrusion formed on the side composed of the silicon oxide film or the silicon nitride film, and the internal stress in the semiconductor crystal layer is generated at the cracked portion. A semiconductor having a light-emitting element which can be relaxed, and thus a high-quality semiconductor crystal layer can be formed in a region originally necessary for forming a light-emitting element without causing a crack, and thus a light-emitting element with favorable light-emitting characteristics. A light emitting element can be formed.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a light emitting element portion manufactured by the method of the present invention, FIG. 2 is a perspective view of the same, 1 is a silicon substrate, and 2 is a semiconductor crystal layer.

An island-shaped semiconductor crystal layer 2 is formed on the front surface side 1a of a silicon substrate 1. The island-shaped semiconductor crystal layer 2 includes, for example, a buffer layer 2a made of gallium arsenide (GaAs), gallium arsenide phosphide (GaAsP), gallium phosphide (GaP), etc., and gallium arsenide, indium gallium arsenide (InGaAs), gallium arsenide phosphide, etc. N-type semiconductor layer 2b, gallium arsenide, indium gallium arsenide,
It is composed of a p-type semiconductor layer 2c such as gallium arsenide phosphide and a p-type semiconductor layer 2d containing a large amount of dopant. The n-type semiconductor layer 2b and the p-type semiconductor layer 2c form a semiconductor junction. The semiconductor crystal layer 2 is covered with the passivation film 3. Then, electrodes 4 and 5 are formed on the p-type semiconductor layer 2d having a large amount of dopant and on the back surface side 1b of the substrate 1. The electrodes 4 and 5 are formed of, for example, chromium or gold (Cr / Au). The light emitting element 6 is mainly formed by the island-shaped semiconductor crystal layer 2 and the electrodes 4 and 5 described above.

The operation of the semiconductor light emitting device 6 thus constructed will be described. When a voltage is applied in the forward bias direction with the upper electrode 4 positive and the lower electrode 5 negative, a second semiconductor layer 2c of p-type is formed. As a result, minority carriers are injected into the first semiconductor layer 2b, and the first semiconductor layer 2 of the semiconductor junction portion which is the interface between the second semiconductor layer 2c and the first semiconductor layer 2b.
At the a-side interface, carriers recombine and emit light. The emitted light passes through the second semiconductor layer 2c and the passivation film 3 and is extracted to the outside.

Next, a method of manufacturing the above semiconductor light emitting device will be described with reference to FIGS. First, as shown in FIG. 3, silicon oxide films 7 and 8 are formed on the entire front surface 1a and back surface 1b of the silicon substrate 1 by a thermal oxidation method.
Specifically, the silicon substrate 1 is 1100 ° C to 1150 ° C.
By oxidizing in the oxygen (O ₂ ) atmosphere for about 60 minutes, the silicon oxide films 7 and 8 having a thickness of 1500Å to 10000Å are formed. As the silicon substrate 1, for example, a single crystal silicon substrate cut off by 2 ° from the (100) plane to the (111) plane is preferably used.

Next, a part of the silicon oxide film 7 formed on the front surface side 1a of the silicon substrate 1 is removed by etching. As a result, a portion (selection region) 9 where the silicon substrate is exposed is formed on the front surface side 1a of the silicon substrate 1. The semiconductor crystal layer 2 is grown in the selected region 9 by an epitaxial method or the like. As a method for growing the semiconductor crystal layer 2, for example, metal organic vapor phase epitaxy or molecular beam epitaxy is used.

FIG. 4 shows a plan view shape of an insulating mask formed by removing a part of the silicon oxide film 7 formed on the front surface side 1a of the silicon substrate 1. The silicon oxide film 7 has a band shape surrounded by sides 7a, 7b, 7c, 7d, and the side 7b is provided with a plurality of protrusions 10 protruding toward the opposite side 7d. The strip-shaped silicon oxide film 7 is formed in the peripheral portion of the region where the light emitting element 6 is formed. The surface 1a of such a silicon substrate 1
Then, when the gallium arsenide layer is epitaxially grown, the gallium arsenide single crystal layer 2 is continuously formed in the plane direction of silicon.
However, cracks are generated in the single crystal layer 2 along the line connecting the protrusions 10 with the protrusions 10 as the starting points. The crack relaxes the internal stress of the semiconductor crystal layer 2 and prevents the crack from entering another portion. Therefore, the crystallinity of the region where the light emitting element 6 is formed becomes very good. In addition,
Since an electrode is formed in the vicinity of the region where the light emitting element 6 is formed on the front surface side 1a of the silicon substrate 1, it is not necessary to grow the semiconductor crystal layer 2 and it can be covered with the silicon oxide film 7. However, when the semiconductor crystal layer 2 is grown in the region where the light emitting element 6 is formed, unless the semiconductor crystal layer 2 is grown in the vicinity thereof, the area of the portion where the semiconductor crystal layer 2 grows on the silicon substrate 1 becomes small. It becomes too much, and a semiconductor crystal grows on the silicon oxide film 7. The semiconductor crystal grown on such a silicon oxide film 7 has poor crystallinity and deteriorates the crystallinity of the epitaxial layer in the region where the light emitting element 6 is formed. Therefore, in the present invention, the semiconductor crystal layer 2 is formed in the vicinity of the region where the light emitting element 6 is formed, but it is desirable that the semiconductor crystal layer 2 in this region also has regular cracks. Therefore, a plurality of island-shaped portions 11 made of silicon oxide are provided between the adjacent strip-shaped portions 7 and cracks are generated along the line connecting the island-shaped silicon oxide films 7. The island-shaped portions 11 are adjacent to each other.
The shape may be such that it projects toward 1. in this way,
Even if a plurality of island-shaped silicon oxide films 11 are provided, cracks can be generated in the semiconductor crystal, and stress in the crystal film can be relieved so that cracks do not occur in other portions.

Next, as shown in FIG. 5, the semiconductor crystal layer 2 grown in the band-shaped portion 7 is divided into a plurality of portions at intervals in the longitudinal direction to form the light emitting element 6. This separation is performed by, for example, photo etching. At this time, the semiconductor crystal layer 2 formed outside the strip portion 7 is also removed.

Thereafter, the passivation layer 3, the front surface side electrode 4 and the back surface electrode 5 as shown in FIG. 1 are formed to complete the light emitting device.

[0016]

As described above, according to the method for manufacturing the semiconductor light emitting device of the present invention, the band-shaped portion surrounded by the side made of silicon oxide or silicon nitride is formed on the silicon substrate, and the band-shaped portion is formed. A semiconductor crystal layer is formed on the silicon substrate by providing a protrusion projecting toward the opposite side on the side of the semiconductor crystal layer, and the semiconductor crystal layer in the band portion is formed into a plurality of islands to form a light emitting element. From the above, a crack is formed in the semiconductor crystal layer starting from the protrusion formed on the side formed of the silicon oxide film or the silicon nitride film, and the internal stress in the semiconductor crystal layer can be relieved at the crack part, so that the light emitting element is A semiconductor light-emitting device having a light-emitting element having a good light-emitting property, which can form a good-quality semiconductor crystal layer without causing cracks in a region originally necessary for formation. It can form a child.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a light emitting device manufactured by a method for manufacturing a semiconductor light emitting device according to the present invention.

FIG. 2 is a perspective view of the same.

FIG. 3 is a process drawing showing a method for manufacturing a semiconductor light emitting device according to the present invention.

FIG. 4 is a diagram showing a strip portion surrounded by a side made of silicon oxide or silicon nitride.

FIG. 5 is a diagram showing another step of the method for manufacturing the semiconductor light emitting device according to the present invention.

[Explanation of symbols]

1 ... Silicon substrate, 2 ... Semiconductor crystal layer, 6 ...
.Light-emitting element, 7 ... band-shaped portion, 10 ... protruding portion, 11
... Islands.

Claims (3)

[Claims] 1. A band-shaped portion surrounded by a side made of silicon oxide or silicon nitride is formed on a silicon substrate,
A semiconductor crystal layer is formed on the silicon substrate by providing protrusions projecting toward opposite sides on the sides of the strip, and the semiconductor crystal layer in the strip is formed into a plurality of islands to form a light emitting element. Method for manufacturing semiconductor light emitting device to be formed. 2. The silicon substrate is provided with a plurality of strip-shaped portions, and a plurality of island-shaped portions made of silicon oxide or silicon nitride is provided between adjacent strip-shaped portions. Method for manufacturing semiconductor light emitting device. 3. The method for manufacturing a semiconductor light emitting device according to claim 2, wherein the island-shaped portion has a shape protruding toward an adjacent island-shaped portion.