JPH01192189A - Manufacture of semiconductor light emitting element - Google Patents

Abstract

PURPOSE:To enable not only the formation of a groove without a strict control and a blocking layer on a substrate through a single process of growing a crystal but also these operations to be done at a high yield rate by a method wherein a groove wedge-shaped and provided with a vertical part in section is formed on a substrate extending in a stripe, and a crystal growth is performed onto the substrate in a single process. CONSTITUTION:A groove 21 is formed on a substrate 11 of a p-type InP single crystal through an etching. The groove 21 is shaped into a wedge form provided with a vertical part in section. A current blocking layer 31 of an n-type InP, a buffer layer 41 of a p-type InP, an active layer 61 of an InGaAsP, and a clad layer 71 of an n-type InP are continuously grown in succession through a liquid phase epitaxial growth performed once. In this process, if the buffer layer 41 is attached to be thicklish, the active layer 61 is shaped into a continuous layer, and if the buffer layer 41 is attached to be thinnish, the active layer 61 is separately provided above the groove 21, and when a laser is made to oscillate, the oscillation is simlified to be in a lateral mode.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the field of optoelectronics, and particularly to a semiconductor light emitting device used as a light source for optical communication and measuring instruments.

(Prior art) -a) In order to manufacture a buried type or V-groove type semiconductor light emitting device, two or more crystal growths are required;
It is better to be able to form a blocking layer with multiple crystal growths.
This is preferable because it reduces thermal deterioration and reduces costs.

An example thereof is a semiconductor laser disclosed in Japanese Patent Laid-Open No. 61-244085.

The structure and manufacturing process of this conventional semiconductor laser will be briefly explained with reference to FIG. First, in FIG. 2(A), a P-type 1nP single crystal is used as the substrate 1, and its <100
＞SiO□ is deposited on the substrate surface la as an etching mask, and the substrate crystal is
A striped window is opened in the 011> direction, and then a groove 2 is etched in the substrate 1 through this window using bromine methanol to form a groove 2 in the 011> direction as shown in FIG.
A substrate 1 in which directional grooves are formed is obtained.

Next, as shown in FIG. 2(B), the grooved substrate 1 is placed in a liquid phase epitaxial apparatus, and the n-type 1nP-! G-current confinement layer 3 is grown. At this time, n-type nP growth melt 3a
does not enter the groove 2 due to its surface tension and does not wet its inner surface.

Next, a buffer layer 4 is grown up to the inner surface of the groove 2 using a p-type InGaAsP growth melt having a low surface tension, and a p-type 1
A first cladding layer 5 of nP, a crescent-shaped active layer 6 of InGaAsP, a second cladding layer of n-type InP, and a first cladding layer 5 of n-type InP.
A cap layer 8 of aAsP is sequentially grown in a liquid phase to obtain a wafer structure as shown in FIG. 2(C). It is known to obtain a semiconductor laser by subsequently depositing the required electrodes.

[Problem to be solved by the invention]

However, in this conventional method, unless the opening width and depth of the grooves extending in a stripe pattern with a dovetail cross section on the substrate are strictly controlled, the n-type InP layer will be formed all the way to the inner surface of the grooves. However, there is a problem in that the current path may be lost.

The present invention is a method for manufacturing a semiconductor light emitting device, which allows grooves to be formed without requiring strict control, and also allows a blocking layer to be formed in a single process of crystal growth on a substrate, and which can be performed at a high yield. The purpose is to provide

[Means to solve the problem]

In order to achieve this object, the present invention has a process of forming a wedge-shaped groove extending in a stripe shape having a vertical section in a substrate, and a process of growing crystals on the substrate in two steps. It is characterized by the following.

[Effect]

Since the groove has a wedge-shaped cross section with a vertical portion, the current blocking layer is divided at the vertical portion of the groove, and a current path is created there. At this time, the blocking layer at the bottom of the groove does not have any adverse effect on the electrical characteristics (performance) of the semiconductor light emitting device.

In addition, by controlling the thickness of the buffer layer of the first conductivity type, the active layer that becomes the light emitting part can be separated.
Furthermore, it has become possible to unify the transverse mode when laser oscillates. In addition, it is easier to process grooves on the substrate, and once the grooved substrate is placed in the liquid phase growth apparatus, the blocking layer, buffer layer, active layer, cladding layer, etc. can be formed by simply controlling the temperature program. The shape of the active layer can be freely controlled by sequentially performing liquid phase epitaxial growth on each layer necessary for the process. Therefore, there is no risk of deterioration or contamination of the interface of the growth layer, and the number of crystal growth steps can be reduced, reducing manufacturing costs and improving yield. The presence of a blocking layer that contributes to current confinement makes it possible to achieve high injection and high output power, and furthermore, by avoiding thermal deterioration of the active layer, it is possible to lower the threshold value.

Furthermore, by controlling the thickness of the buffer layer, the active layers are spaced apart in a crescent shape. This allows the transverse mode to be unified.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 (A>, (B), and (C) are explanatory diagrams for explaining a manufacturing method showing an example of the present invention, and FIG.
) is a perspective view of the substrate, FIG. 1(B).

(C) is a cross-sectional view of the semiconductor light emitting device.

A p-type 1nP single crystal is used as the substrate 11, and its <100
>Plug 5tsN4 on the board surface 11a by vCVD (Ch
chemical vapor deposition
n) Depositing with equipment. A resist is applied on top of it using a spinner and prebaked.

Next, the resist is exposed to light using a mask aligner so that striped windows are opened in the <011> direction of the substrate crystal. Furthermore, after removing the resist in the pattern area with a developer, post-baking is performed. Next, remove S from the pattern area using a hydrofluoric acid etchant (HF:NHmF=3:20).
After etching t:+N, the resist is completely removed using acetone or a remover. Through this series of photolithography techniques, a groove 21 is etched into the substrate 11 on which an etching mask with striped windows is attached using J-hydrochloric acid through the windows. In this case, the cross-sectional shape of the groove 21 cut along a plane normal to the stripe direction of the groove 21 is wedge-shaped with a vertical portion. The vertical portion becomes the <011> surface of the groove side surface. (
(See Figure 1 (A)) Next, Si
, N is removed from the entire surface, and then this grooved substrate 11 is set in a liquid phase epitaxial growth apparatus. n-type InP
The current blocking layer 31, the p-type 1nP layer 41, the active layer 61 of InGaAsP, and the cladding layer 71 of the n-type 1nP layer are successively grown in one liquid phase epitaxial growth process. At this time, if the buffer layer 41 is deposited thickly, the active layer 61 will have a continuous layered shape, as shown in FIG.
As shown in Figure (C), when the active layer 61 is spaced above the groove 21 and laser oscillation is performed, the transverse mode is unified.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to manufacture a double heterostructure semiconductor light emitting device having an internal current blocking layer by forming grooves in advance in a substrate and performing liquid phase epitaxial growth once, thereby achieving a high implantation level. It is possible to obtain a semiconductor light emitting device that can output and has a low threshold value. Moreover, by disposing the active layer of the light emitting part on the groove, a semiconductor light emitting device having a characteristic of oscillating in a single fundamental transverse mode can be manufactured at low cost and with high yield.

[Brief explanation of the drawing]

FIGS. 1(A), (B), and (C) are explanatory diagrams for explaining a method for manufacturing a semiconductor light emitting device according to an embodiment of the present invention, and FIGS. 2(A), (B), and ( C) is an explanatory diagram for explaining a conventional method for manufacturing a semiconductor light emitting device. 1- p-type 1nP substrate, 1a...-<lOO> substrate surface. 2... Pigeon-shaped groove, 3... n-type 1nP current confinement layer. 4...p-type 1 nGaAs P buffer layer. 5... P-type 1nP first cladding layer. 6 = In Ga As P active layer. 7...N-type 1nP second cladding layer. 8 - n-type 1 nGaAs P cap layer. 3a...N-type 1nP growth melt. 11...p-type rnP substrate. lla...<100> Board surface. 21... Wedge-shaped groove having a vertical portion. 31...n type 1n P current blocking layer. 41...p-type 1nP buffer layer. 61-1 nGaAsP active layer. 71...n-type InP cladding layer.

Claims (2)

[Claims] (1) A step of forming, by etching, a groove extending in a wedge-shaped stripe shape having a vertical section on a first conductivity type III-V compound semiconductor crystal substrate, and the substrate processed by the step. A blocking layer of the second conductivity type separated by the vertical part of the groove, a buffer layer of the first conductivity type, an active layer serving as a light emitting part, and a cladding layer of the second conductivity type are formed on the top by a single liquid solution. A method for manufacturing a semiconductor light emitting device, comprising a step of forming it by phase epitaxial growth. (2) The method for manufacturing a semiconductor light emitting device according to claim 1, wherein the active layer of the light emitting section is spaced apart above the groove.