JPH07263809A - Crystal manufacture method - Google Patents

Abstract

PURPOSE:To provide a crystal manufacturing method for excellently making a light-emitting element from AlGaInN crystal. CONSTITUTION:The {1-100} or {11-20} face of sapphire is used as a substrate crystal and a ZnO layer 12 is put on it and successively AlGaIn series hetero structures 13 to 17 are grown, and the ZnO layer is dissolved by an acid to separate AlGaInN heterocrystal and the herterocrystal is split. Thereby, the excellent split plane which is essential to form a Fabry-perot cavity is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal manufacturing method for manufacturing a light emitting device using an AlGaInN type crystal.

[0002]

2. Description of the Related Art Blue light emitting diodes using AlGaInN group IIIV semiconductors have been put to practical use. This device is basically manufactured by growing an AlGaInN-based double hetero crystal on the {0001} plane of a sapphire substrate crystal.

[0003]

The light emitted from the light emitting diode does not have a strong directivity and the energy density of the light is low. Therefore, development of a semiconductor laser is desired for applications such as information processing equipment other than display elements, industrial equipment, and office equipment. In principle, it is possible to make a semiconductor laser that emits light of wavelengths from green to blue and further into the ultraviolet region by using AlGaInN type crystals. One of the reasons that hinders the realization of this is that the technology for forming the end faces with high reflectance, which is indispensable for forming Fabry-Perot cavities, has not been developed. The basic requirements for forming a good end face are (1) that the crystal is sufficiently thin and easy to cleave, and (2) that an appropriate cleave plane exists. Nitride crystals have higher hardness and are less prone to cleavage than arsenide or phosphide crystals, which are typical IIIV compounds. In the latter case, which is easily cleaved, in order to obtain a good end face, the thickness must be reduced to 100 μm. In a nitride crystal, it is necessary to make it thinner by one digit. Further, if the crystal plane to be epitaxially grown is the {0001} plane, there is no crystal plane perpendicular to this plane and exhibiting good cleavage characteristics. Therefore, it is necessary to consider epitaxial growth on a crystal plane of the substrate other than {0001}.

An object of the present invention is to provide a crystal manufacturing method for satisfactorily forming a light emitting device with an AlGaInN type crystal.

[0005]

A crystal plane near {1-100} or {11-20} of sapphire is adopted as a crystal plane of a substrate, and a ZnO crystal layer is first grown on the crystal plane, and an AlGaInN-based crystal plane is further grown. A double heterocrystal was grown, and then the ZnO layer was dissolved away with an acid to obtain A
A good end face can be obtained by cleaving the 1GaInN-based crystal layer along the {0001} plane.

[0006]

In the wurtzite type crystal, the {0001} plane shows the best cleavage. In addition, a device such as a semiconductor laser made of an AlGaInN-based double heterocrystal is often 10 μm or less in thickness. Therefore, the cleavage can be easily performed.

[0007]

The present invention will be described with reference to FIG. The substrate crystal 11 adopts the {1-100} plane of sapphire.
The substrate crystal is ultrasonically cleaned with an organic solvent, and then the surface is chemically etched with heated H ₃ PO ₄ : H ₂ SO ₄ = 1: 3. The wafer is washed with water and dried, and then the ZnO microcrystal layer 12 having a thickness of 50 nm is formed by the RF sputtering method.
To wear. An AlGaInN-based crystal is grown on this. For this, trimethylaluminum, trimethylgallium, and trimethylindium are used as group III element precursors, ammonia is used as group V element precursors, and disilane and diisopropylmagnesium are used as n-type and p-type dopant precursors, respectively. Adopt the growth method. This Z
A sapphire substrate crystal with an nO layer is attached to a reaction tube and heated to 1050 ° C. in a nitrogen stream.

First, trimethylgallium, disilane, and ammonia are made to flow to make the n-GaN layer 13 have a thickness of 10 μm, and trimethylaluminum is added to this to make the n-AlGaN layer 1
4 to 0.2 μm, trimethylgallium, trimethylindium, and ammonia to make the u-GaInN layer 15 0.1 μm, trimethylaluminum, trimethylgallium, diisopropylmagnesium, and ammonia to make the p-AlGaN layer 16 0.1 μm and trimethylgallium. , Diisopropylmagnesium and ammonia are caused to flow to sequentially grow the p-GaN layer 17 to 2 μm (FIG. 1A). When this wafer is taken out and immersed in aqua regia, the ZnO layer 12 is dissolved and the AlGaInN-based crystal layer can be separated from the sapphire substrate 11 (FIG. 1).
(B)). When the separated crystal layer is divided along the {0001} plane 18, a chip 19 having a good end face is obtained (FIG. 1 (c)). In this embodiment, the growth on the {1-100} plane has been described as an example, but the same applies to the {11-20} plane.

[0009]

According to the present invention, it is possible to obtain a clean cleavage surface which is indispensable for forming Fabry-Perot cavities.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a crystal manufacturing process (wafer cross-sectional view) of the present invention.

[Explanation of symbols]

11 ... (1-100) sapphire substrate crystal, 12 ... Zn
O crystal layer, 13 ... n-GaN layer, 14 ... n-AlGaN
Layers, 15 ... u-GaInN layer, 16 ... p-AlGaN
Layer, 17 ... p-GaN layer, 18 ... {0001} plane, 19
… Tips.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Otoshi 1-280 Higashi Koigakubo, Kokubunji, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd.

Claims (1)

[Claims] 1. Sapphire {1-100} or {11
ZnO layer is grown on the −20} plane, and then AlGa
An InN-based double hetero crystal layer is grown, the ZnO layer is dissolved with an acid to separate the double hetero crystal layer from the substrate crystal, and then the double hetero crystal layer is cleaved along the {0001} plane. A method for producing a crystal characterized by the above.