JP2001177146A - Triangular shape semiconductor element and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor element capable of easily isolating an element from an epitaxial wafer in high yield and having no maldistribution of a injected carrier amount as fast as possible. SOLUTION: The triangular shape semiconductor element comprises a laminated structure for sequentially growing an Si-doped n-type GaN layer 2 through a GaN or AlN buffer layer 1 on a sapphire (c) surface substrate 1, an n-type AlGaN clad layer 31, an InGaN MQW light emitting layer 4, an Mg-doped p-type AlGaN clad layer 32, and a p-type GaN contact layer 5. In this case, the profile shape of the element becomes a triangular shape surrounded at its sidewall by and equivalent M surface ( 1-100} surface). Since such an element structure has an equivalent surface of the sidewall surface, hence has entirely equal crackableness and a sectional shape. Thus, the isolation of the element can be facilitated at a high quality level. As a result, the yield of the product can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a triangular semiconductor device having a hexagonal compound semiconductor layer, for example, a semiconductor light emitting device and a light receiving device.

[0002]

2. Description of the Related Art In recent years, light emitting elements and light receiving elements made of GaN-based compound semiconductors have been actively developed. Generally, the element is formed in a cubic shape, and the shape of the element viewed from above is a square or a rectangular shape. Incidentally, GaN-based compound semiconductors are often crystal-grown on a sapphire substrate, but sapphire is also Ga
Since N is also a hard material, it is difficult to completely cut out the element only by dicing. For this reason, it is common to make a scratch by partial dicing or scribing, and to separate the elements by dividing the scratch as a starting point.

[0003]

SUMMARY OF THE INVENTION However, GaN
In a hexagonal compound semiconductor such as that described above, it is difficult to determine both surfaces orthogonal to each other, that is, all surfaces of a rectangular element, with high quality from the basic structure of the crystal. For example,
The sapphire substrate has the property that the M plane ({1-100} plane) is easily cracked, but the orthogonal A plane ({11-20} plane) is hard to crack. However, there is a problem that scribing cannot be neatly divided on the A side. Therefore, when manufacturing a rectangular semiconductor element using a hexagonal compound semiconductor,
A surface where high-quality division cannot be performed must be provided inevitably, and there is a problem that the possibility of occurrence of defective products increases when the element is scribed and separated from the epitaxial growth substrate.

In the case of a rectangular semiconductor light emitting device in which a semiconductor layer is grown on an insulating substrate such as sapphire,
As the electrodes, bonding electrodes are generally formed at opposing corners of the rectangular element.
(Japanese Utility Model Registration 3027676). However, with such an element structure and an electrode structure, there is a problem that the amount of carriers injected into a region near the remaining corner where the bonding electrode is not disposed is small.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a semiconductor device which can easily perform device isolation from an epitaxial wafer with a high yield, and furthermore does not cause uneven distribution of a carrier injection amount as much as possible. I do.

[0006]

According to the present invention, there is provided a semiconductor device comprising:
A hexagonal crystal substrate, a triangular semiconductor element comprising a hexagonal compound semiconductor formed thereon,
The surface around the side of the hexagonal compound semiconductor is {1-10}
The hexagonal crystal substrate may be constituted by a {1-100} plane.

The present invention is particularly suitable when the above-mentioned semiconductor is mainly composed of GaN. Specifically, <
A triangular semiconductor element obtained by growing a thin GaN-based compound semiconductor layer on a thick sapphire substrate having cut surfaces in three directions equivalent to the 1-100> direction is preferable.

In a more specific semiconductor device of the present invention, the hexagonal compound semiconductor layer has at least two or more semiconductor layers having different conductivity types, and an electrode pattern to be provided to the triangular semiconductor device is formed by the following method. A transparent electrode formed on the surface of the one conductivity type semiconductor layer, a first bonding electrode disposed on the transparent electrode and near one vertex of a triangle,
The surface of the semiconductor layer of the second conductivity type, which is exposed by a partial cutout of the semiconductor layer of the first conductivity type, is brought close to the side of a triangle facing the vertex on which the first bonding electrode is arranged. And a second bonding electrode arranged in the same direction.

In the above structure, it is desirable that a curved surface be provided at each corner of the triangular semiconductor element.

Further, in the method of manufacturing a semiconductor device according to the present invention, a laminate is formed by growing a hexagonal compound semiconductor on a hexagonal crystal substrate and forming a laminate on the substrate side surface of the laminate. The lamination is performed by making scribe flaws in three directions corresponding to the <11-20> direction, or making scribe flaws in three directions corresponding to the <11-20> direction of the semiconductor crystal on the semiconductor side surface, and dividing along the scribe flaws. It is characterized by obtaining a triangular semiconductor element from a body.

[0011]

According to the structure of the present invention, the triangular element structure in which the periphery is formed by a fragile surface (for example, the M surface of sapphire), so that the element side wall is formed with high quality. Can be provided. That is, when the element is separated from the epitaxial growth substrate, the division can be performed simply and with good quality of the side wall only by making a scribe flaw. As a result, an additional effect that the light extraction efficiency is improved is also exhibited.

Further, by arranging the bonding electrodes according to the fifth aspect, a current can flow from one vertex of the triangle to the opposite side, so that carrier injection can be performed on the entire chip, and the rectangular element can be formed. In this case, the problem of uneven distribution of carrier injection which is a problem in the case of (1) can be solved.

Further, according to the method of manufacturing a semiconductor device of the present invention, the hexagonal crystal substrate or the compound semiconductor is kept at 120 °.
Although there are three <11-20> direction lines that are shifted from each other, it is possible to cause some surface disorder by scribing and breaking along these lines. The surface can be substantially {1-100} plane, and a triangular semiconductor element surrounded by a high-quality plane can be manufactured.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail. FIG. 1 is a diagram showing an example of a general GaN-based LED structure. Referring to the figure, on a sapphire c-plane substrate 1, a Si-doped n-type GaN layer 2, n is interposed via a GaN or AlN buffer layer 10 grown at a low temperature.
-Type AlGaN cladding layer 31, InGaN-based MQW light-emitting layer 4, Mg-doped p-type AlGaN cladding layer 32,
The p-type GaN contact layer 5 is sequentially grown to form an epitaxial growth substrate (epi substrate) having an element structure. At this time, it is known that the plane direction of the sapphire substrate 1 and the plane direction of the GaN-based device structure D are shifted by 30 degrees. That is, the M and A planes of the sapphire substrate 1 are the A and M planes of the GaN-based device structure D.

Normal photolithography technology, RIE
After the element is formed using the technology and the electrode formation technique, the element is scribed at the diamond point from the sapphire surface side, and then subjected to mechanical bending stress to break (break) to separate the element. At this time, since the sapphire substrate is overwhelmingly thick, the finish of element isolation is largely influenced by the way the sapphire substrate is broken. When a chip is cut out in a rectangular shape as shown in FIG. 1, the side surface is surrounded by a sapphire A plane ({11-20} plane) and an M plane ({1-100} plane). At this time, the M surface becomes a relatively flat surface, and the A surface becomes a rattled rough surface. On the other hand, the M plane also has a property that an R plane ({1-102} plane), which is a cleavage plane of sapphire, is likely to be generated, and special attention is required.

That is, since the properties of the planes orthogonal to each other are greatly different, special attention must be paid to the element separation step, and the shape of the obtained chip is strongly anisotropic. For this reason, abnormal cracking frequently occurs, which is a factor that lowers the product yield.

On the other hand, FIG. 2 shows GaN according to the present invention.
1 shows an example of a system LED structure, in which an n-type GaN layer 2 doped with Si, an n-type AlGaN cladding layer 31, an InGaN-based MQW light emitting layer is formed on a sapphire c-plane substrate 1 via a GaN or AlN buffer layer 10 grown at a low temperature. 4, a stacked structure in which a Mg-doped p-type AlGaN cladding layer 32 and a p-type GaN contact layer 5 are sequentially grown is the same as described above. It is different in that it has a triangle surrounded by ({1-100} plane). With such an element structure, since the side wall surfaces are equivalent surfaces, they have exactly the same fragility and cross-sectional shape, and element isolation can be performed easily and with high quality, thereby improving the product yield. Can be achieved. In the present invention, the {1-100} plane does not only indicate that the plane is a {1-100} plane without fail, but also inevitably occurs when scribed or divided into elements. This allows a slight error that would otherwise occur.

As shown in the figure, the electrode pattern provided to the triangular GaN-based LED includes a transparent electrode 71 formed on the surface of the p-type GaN contact layer 5 and a triangular one on the transparent electrode 71. A first bonding electrode 61 disposed near two vertices and the surface of the n-type GaN layer 2 exposed by a partial cutout of the p-type semiconductor layer, wherein the first bonding electrode 61 is disposed. The second bonding electrode 62 is arranged close to the side of the triangle facing the apex, and a strip electrode 72 extending from the second bonding electrode 62.

By arranging the positional relationship of the extraction electrodes in this manner, the distance from the first bonding electrode 61 formed at the apex of the triangle to the side on which the second bonding electrode 62 is formed becomes substantially equal. As a result, uniform current injection can be achieved. In the case of a light emitting device, the external quantum efficiency can be improved by about 15% as compared with the case of a square.

The hexagonal compound semiconductor used in the present invention includes, for example, GaN, AlGaN, InGaAlN,
nGaN and the like can be exemplified. When the target semiconductor device is a light emitting device, a GaN buffer layer, a Si
Doped n-GaN layer, Si-doped n-AlGaN layer, I
nGaN-based multilayer quantum well structure layer, Mg-doped p-AlG
A multilayer structure including an aN layer and a Mg-doped p-GaN layer can be exemplified.

The hexagonal crystal substrate used in the present invention includes a sapphire substrate, a SiC substrate, a GaN substrate, a Z
Various hexagonal crystal substrates such as nO can be used, but in order to improve the quality of the hexagonal compound semiconductor grown on this substrate, a sapphire substrate, SiC
It is preferable to use a substrate and a GaN substrate.

As a typical embodiment of the present invention, as described above, there is an LED in which a light emitting layer made of a GaN-based compound semiconductor is grown on a sapphire substrate. In this case, the plane direction of the sapphire substrate and the plane direction of the GaN-based compound semiconductor are shifted by 30 degrees. However, in general, devices such as LEDs generally have a GaN-based compound semiconductor layer constituting a light-emitting portion or the like of about 10 μm or less. The sapphire substrate has a thickness of about 50 to 500 μm. Therefore, in such a case, if the cut surface of the thick sapphire substrate is separated so as to have cut surfaces in three directions substantially equivalent to the <1-100> direction, an easy and high-quality device can be obtained. Separation can take place.

The triangular semiconductor element of the present invention can be obtained by separating elements from an epitaxial growth substrate such that each element has a triangular shape and the separation plane is substantially {1-100} plane. . As a method of such separation, scribed scratches are made in three directions corresponding to <11-20> directions of the substrate crystal on the substrate side surface of the epitaxial growth substrate, and a mechanical force is applied along the scribed scratches with a knife edge. For example, and a method of dividing.

In a normal case where the substrate is sufficiently thicker than the semiconductor layer, the above method may be used. For example, in the case of a GaN-based semiconductor light emitting device, a mode in which a GaN-based compound semiconductor layer having a thickness of several μm is laminated on a sapphire substrate having a thickness of about 80 μm is used. In this case, scribe marks are formed on the back surface of the sapphire substrate. If broken, there is a 30 ° deviation between the {1-100} plane of sapphire and the {1-100} plane of GaN, but due to the superiority due to thickness, the entire {1-100} plane of sapphire ｝ Will be divided on the surface. On the other hand, in a special device in which the sapphire substrate has a thickness of about 40 μm and the GaN-based compound semiconductor layer has a thickness of about 20 μm,
If the GaN layer is divided from the back surface side of the sapphire substrate, the GaN layer may be superior in mechanical strength and a clean divided surface may not be obtained. The scribe scratches may be made in three directions, i.e., three directions. In the case where a SiC substrate or a GaN substrate is used instead of sapphire, the above-described deviation of the {1-100} plane does not occur, and thus the substrate may be divided from either the substrate side or the semiconductor side.

The arrangement positions of the bonding electrodes 61 and 62 may be such that one is located at the vertex of the triangle and the other is at an arbitrary position along the side facing the vertex. For example, FIG.
In the above, the second bonding electrode 62 is arranged at the center of the opposing side.
1 may be arranged near any of the remaining two vertices where no 1 is arranged. Further, the second bonding electrode 62 is disposed at the top, and the first bonding electrode 6
1 may be arranged near the center of the opposite side.

As the transparent electrode 71, an electrode composed of a substantially transparent conductive thin film is used. In addition, an electrode which is opaque but has substantially transparent by providing an electrode pattern in a comb shape is used. It may be. In addition, the strip electrode 72
May be provided as needed to further improve the current injection efficiency.

When a GaN-based device structure is formed on a GaN substrate, the substrate and the device structure have the same crystallographic orientation.
(−100 ° plane) is more preferable because three sides are enclosed. Further, since the substrate is a conductive substrate, the first bonding electrode 61 can be provided at any corner of the vertex of the triangle or near the center.

In the present invention, since the semiconductor element has a triangular shape, its corners tend to be sharper than a rectangular element and tend to be susceptible to mechanical damage. Therefore, it is desirable to apply a chamfered curved surface to the corner portion. As a method of forming the curved surface, a method of applying a mask shape for etching to the curved surface or the like can be adopted.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments will be described below. This embodiment shows an example in which a device structure is formed on a sapphire substrate having the structure shown in FIG. The crystal growth apparatus used is a normal MOVPE apparatus. First, a sapphire c-plane substrate is loaded into a predetermined place in a reaction tube of a MOVPE apparatus, and
Thermal cleaning was performed in a hydrogen atmosphere at 50 ° C. for 5 minutes. Next, lower the substrate temperature to 350 ° C.
A buffer layer of N was grown to a thickness of 20 nm, and after raising the temperature to 1000 ° C., n-GaN of 3 μm was grown. The dopant is Si. Further, n-AlGaN having a thickness of 50 nm was grown, and the substrate temperature was lowered to 700 ° C. to grow an InGaN-based layer (MQW structure, three well layers). again,
After raising the temperature to 1000 ° C., Mg-doped p-AlGaN
A layer was grown to 30 nm, followed by a p-GaN layer. The atmosphere in the reaction tube was switched to nitrogen gas and cooled to room temperature.

The device was processed on the epitaxial substrate using ordinary photolithography technology, reactive ion etching technology (RIE), and vacuum deposition technology. Since the sapphire substrate has a thickness of 350 μm, the whole was polished to 80 μm. Thereafter, scribing was performed from the sapphire substrate side in three directions equivalent to the <11-20> direction at a point with a diamond blade. Element separation was performed by applying mechanical force with a knife edge along the scribed scratch. As a result, the LE surrounded by the equivalent {1-100} plane
A D chip was produced.

[0031]

As described above, according to the triangular semiconductor device of the present invention, the surface forming the side periphery is {1-10}.
Because of the 0 ° plane, each end face of the device chip is braked in a uniform shape during element division from the epitaxial growth substrate. Therefore, it is possible to obtain a semiconductor element having an extremely high-quality side periphery and to improve the product yield. Further, the triangular shape allows carrier injection to occur evenly over the entire surface, so that quantum efficiency can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a conventional rectangular GaN-based LED structure.

FIG. 2 is a perspective view showing a triangular GaN-based LED structure of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 31, 32 Cladding layer 4 Light emitting layer 61, 62 Bonding electrode D GaN device structure

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoichiro Ouchi 4-3 Ikejiri, Itami-shi, Hyogo Mitsubishi Cable Industries, Ltd. Itami Works F-term (reference) 5F041 AA03 AA41 CA05 CA23 CA34 CA40 CA46 CA65 CA74 CA76 CA77 CA88

Claims (7)

[Claims] 1. A triangular semiconductor element comprising a hexagonal crystal substrate and a hexagonal compound semiconductor formed thereon, wherein the surface around the side of the hexagonal compound semiconductor is Δ1. A triangular semiconductor element characterized by having a -100 ° plane. 2. A triangular semiconductor device comprising a hexagonal crystal substrate and a hexagonal compound semiconductor formed thereon, wherein a surface around a side of the hexagonal crystal substrate is Δ1. A triangular semiconductor element characterized by having a -100 ° plane. 3. The semiconductor device according to claim 1, wherein the hexagonal compound semiconductor is mainly composed of GaN. 4. A triangular thick sapphire substrate having a {1-100} plane around the side, and a thin G
3. The triangular semiconductor device according to claim 2, wherein an aN-based compound semiconductor layer is grown. 5. The hexagonal compound semiconductor layer has at least two or more semiconductor layers having different conductivity types, and an electrode pattern to be applied to the triangular semiconductor element is formed on a surface of the first conductivity type semiconductor layer. A transparent electrode to be formed, a first bonding electrode disposed on the transparent electrode near one vertex of a triangle, and a second bonding electrode exposed by a partial cutout of a semiconductor layer of the first conductivity type. A second bonding electrode disposed on the surface of the conductive semiconductor layer, the second bonding electrode being disposed in close proximity to a triangular side opposed to the vertex on which the first bonding electrode is disposed. Item 3. The semiconductor element according to item 1 or 2. 6. A curved surface is provided at each corner of the triangular semiconductor element.
6. The semiconductor device according to any one of items 1 to 5, 7. A laminate is formed by growing a hexagonal compound semiconductor on a hexagonal crystal substrate, and a laminate is formed on the substrate-side surface of the laminate in three directions corresponding to <11-20> directions of the substrate crystal. Obtaining a triangular semiconductor element from the laminate by scribing or scribing in three directions corresponding to the <11-20> direction of the semiconductor crystal on the semiconductor side surface and dividing along the scribing. A method for manufacturing a semiconductor device, comprising: