JPH0237783A - Manufacture of end-face light-emitting type optical semiconductor device - Google Patents

Abstract

PURPOSE:To accurately evaluate an optical output characteristic of a light-emitting element on a wafer by a method wherein an optical output face and an optical reflection face are formed on the wafer so as to be faced by utilizing an end face of an element region. CONSTITUTION:A semiconductor substrate 10 and a P-side ohmic electrode 60 are brought into contact only in a contact region 50; this region is separated from the semiconductor substrate 10 in a peripheral part by using grooves 30 which are deeper than a p-n junction region 20. Since an element isolation region 90 is formed in the P-side ohmic electrode 60, light-emitting elements are separated electrically inside a wafer. Accordingly, when an N-side electrode is taken out from the whole surface of an N-side ohmic electrode 70 and an electric current flows to a gold-plated layer 80 on the P-side ohmic electrode 60 of the individual light-emitting elements, a beam is radiated through a silicon nitride film 40 from an optical output face 100; this beam is reflected by an optical reflection face 110 at an end part of an adjacent element facing the optical output face 100; the beam is taken out in a vertically upward direction; accordingly, a photodetector is arranged in parallel with a wafer face. Thereby, it is possible to accurately evaluate an optical output characteristic of the light-emitting elements on the wafer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing an edge-emitting optical semiconductor device, and more particularly to a method for manufacturing a wafer that allows easy evaluation of the light output characteristics of an edge-emitting element.

[Conventional technology]

Conventionally, edge-emitting optical semiconductor devices are manufactured by cleaving edge-emitting elements on a wafer in a direction perpendicular to the light output direction and separating them from each other, and the cleavage planes formed at this time are used as light output surfaces. used. Therefore, the optical output characteristics are measured for each element separated from the wafer, and the light receiving element is placed at a position facing the cleavage plane for evaluation.

[Problem to be solved by the invention]

As described above, according to the conventional manufacturing method, the evaluation of the light output characteristics of edge-emitting light emitting devices needs to be performed individually separated from the wafer, which takes time and significantly impedes productivity in evaluation tests. are doing. Further, there are drawbacks such as difficulty in obtaining data for evaluating the characteristic distribution of elements within the wafer plane, which is necessary for production control.

In view of the above-mentioned circumstances, an object of the present invention is to provide a method for manufacturing an edge-emitting optical semiconductor device in which a light output characteristic evaluation test of a light emitting element can be performed with high precision on a wafer.

[Means to solve the problem]

According to the present invention, a method for manufacturing an edge-emitting optical semiconductor device includes an element forming step in which a plurality of edge-emitting optical semiconductor elements are electrically separated from each other and arranged in rows and columns on one semiconductor substrate; A semiconductor wafer manufacturing process including a step of forming a light reflecting surface to face the light output surface and forming a light reflecting surface upwardly on the substrate for the light output of the light emitting semiconductor element at the end of each adjacent element. It consists of:

〔Example〕

The present invention will be described in detail below with reference to the drawings.

FIG. 1, FIG. 2, and FIG. 3 are partial perspective views of a semiconductor wafer showing an embodiment of the present invention in the production of FP type photodiodes, and AA' and B thereof, respectively.
-B' sectional view.

That is, according to this embodiment, on the semiconductor wafer,
A plurality of single-sided light-emitting FP type photodiode elements have their light output surfaces 100 facing in the same direction, and the elements on one side of the mutually opposing row reflect the output light of the elements on the other side vertically upward. A light reflecting surface 110 is provided at each end so that the light reflecting surfaces 110 are arranged in a matrix.

First, a pn junction region 20 is formed by epitaxial growth on an n-type InP substrate 10, and then selectively etched using photolithography to form a groove 30 for current confinement and epitaxial layer separation and a light output surface 10.
0 and the light reflecting surface 110 are each formed deeper than the pn junction region 20. At this time, the groove 30 for power confinement and epitaxial layer separation and the light output surface 100 are etched with a bromine-based etching solution under the condition that the difference in etching rate depending on the plane orientation of the crystal is not significant.
The light reflecting surface 110 is etched using a sulfuric acid-based etching solution under conditions where there is a significant difference in etching rate depending on both crystal values.

Next, a silicon nitride film 40 is grown by plasma CVD. The thickness of the grown film at this time is about 1,800 thick to provide anti-reflection (AR) conditions for the emission wavelength of 1.3 μm. Next, using photolithography technology, this silicon nitride film 40 is selectively etched to form a contact region 50.
A p-side ohmic electrode 60 made of a chromium-gold (Cr-Au) material is selectively formed on the upper surface of the p-side ohmic electrode 60. Next, the back surface is polished to a thickness of about 100 μm, and then gold germanium-gold nickel (AuG
N-side ohmic N made of e −A u N i ) material
% 70, and a gold plating layer 80 with a thickness of 5 μm is further formed on the P-side ohmic electrode 60 to improve heat dissipation.

In the semiconductor wafer of this embodiment, the contact between the semiconductor substrate 10 and the P-side ohmic electrode 60 is in the contact region 50.
The surrounding semiconductor substrate 10 is made to have a structure consisting of only
and are separated by a groove 30 deeper than the pn junction region 20, and an element isolation region 90 is formed in the P-side ohmic electrode 60, so that individual electrical connections are made within the FP type photodiode element wafer. are in a state of separation. Therefore, if the N-side electrode is removed from the entire surface of the N-side ohmic electrode 70 and a probe is applied to the gold plating layer 80 on the P-side ohmic electrode 60 of each light emitting element and a current is applied, the light output surface 100 will be free from reflection. Light is efficiently emitted through the silicon nitride film 40 set to the (AR) condition, and is further reflected by the light reflection surface 110 at the end of the adjacent element formed to face the light output surface 100, perpendicular to the wafer surface. It is taken out upwards. Therefore, if the light receiving element is placed parallel to the wafer surface, it becomes possible to evaluate the light output characteristics of each light emitting diode element in the wafer state.

As shown in FIGS. 2 and 3, after the light output characteristics are evaluated in the wafer state, the wafer is moved along a line c-c' parallel to the light emitting surface and a line D perpendicular to the light emitting surface.
-D' to form individual light emitting diode elements.

FIG. 4, FIG. 5, and FIG. 6 each illustrate the present invention using a DFB.
A partial perspective view of a semiconductor wafer showing an example of drilling carried out in the fabrication of a type light emitting diode, and its AA';
It is a BB' cross-sectional view.

According to this embodiment, on a semiconductor wafer, a plurality of double-sided light emitting RJFB type light emitting diode elements reflect light output from a light reflection surface 110a that vertically reflects its own light output and an output surface 100 of an adjacent element. The light reflecting surfaces 110b for adjacent vertically reflecting elements are arranged in rows and columns.

First, after forming a pn junction region 20 by epitaxial growth on an n-type InP substrate 10, selective etching is performed to form a structure 30 for current confinement and epitaxial growth layer separation, a light output surface 100, this element itself, and the like, as in the previous embodiment. Light reflecting surfaces 110a and 110b for adjacent elements
and are formed deeper than the pn junction region 20, respectively. That is, substantially the light output surface 100 and the light reflection surface 110a
, 110b are formed on both sides of each element. As in the previous embodiment, a silicon nitride film 40 is grown by plasma CVD. The thickness of the grown thick film at this time is about 1,800 to provide an anti-reflection (AR) condition for the oscillation wavelength of 1.3 μm. Next, using photolithography technology, this silicon nitride film 40 is selectively etched to form a contact region 50, and a P-side ohmic electrode 60 made of a chromium-gold (Cr--Au) material is selectively formed on the upper surface of the contact region 50.

Next, backside polishing is performed to reduce the total thickness of the wafer to 10
After reducing the thickness to approximately 0 μm, a metal film made of gold germanium-gold nickel (AuGe-AuNi) for the N-side ohmic electrode 70 is formed, and a gold plating layer 80 is further formed to a thickness of 5 μm on the P-side ohmic electrode 60 to improve heat dissipation. It is formed to a thickness of . In this embodiment as well, each element is electrically isolated from each other within the wafer plane by the groove 30 and the element isolation region 90, so that by passing a current through each element as in the previous embodiment, both sides of the element can be isolated. Light is emitted from the light output surfaces 100 formed in the wafer, and is further reflected by the light reflection surfaces 110a and 110b formed facing the light output surfaces 100, respectively, and is extracted in a direction perpendicular to the wafer. Therefore, by installing the light receiving element parallel to the wafer surface, it becomes possible to evaluate the light output characteristics of each light emitting diode element in the wafer state. In this way, after the light output characteristics have been evaluated in the wafer state and defective devices have been marked, the wafer is placed in the direction c-c' parallel to the light-emitting surface and the light-emitting surface as shown in FIGS. 5 and 6. and are separated along the vertical direction DD' to form individual light emitting diode elements. At this time, the light reflecting surface 110b
The optical output from the is used for monitoring purposes. This DFB
Unlike FP-type elements, FP-type light emitting diodes amplify light using an internal resonator, so as long as the reflectance of the light-reflecting surface is adjusted to zero using a silicon nitride film 40, it can be mirror-like. Since this is not necessary, the present invention is very easy to implement.

〔Effect of the invention〕

As explained in detail above, according to the present invention, when manufacturing an edge light emitting device, the light output surface and the light reflection surface are formed on the wafer so as to face each other using the edges of the device regions, so that light emitting It is possible to evaluate the optical output characteristics of the device in the wafer state. Therefore, productivity can be significantly increased compared to conventional manufacturing methods in which evaluation is performed in separate states, and it is also possible to easily obtain property distribution evaluation data within the wafer surface, which is necessary for production control, which is useful for improving manufacturing technology. It can produce remarkable effects.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, and FIG. 3 are partial perspective views of a semiconductor wafer showing an embodiment of the present invention in the production of FP type photodiodes, and AA' and B thereof, respectively.
-B' sectional view, FIG. 4, FIG. 5, and FIG. 6 are a partial perspective view of a semiconductor wafer and its AA' B- It is a B' sectional view. 10... n-type InP substrate, 20... pn junction region,
30... Groove for current confinement and epitaxial layer separation, 40... Silicon nitride film, 5o... Contact region, 60... P-type ohmic electrode, 7°... N
Type ohmic electrode, 80... Gold plating layer, 90...
Element isolation region, 100...light output surface, 11o. Oa. b...Light reflecting surface. Flute diagram Song Xia V tea subordinate female leaning male Ma diagram

Claims (1)

[Claims] An element forming step in which a plurality of edge-emitting optical semiconductor elements are electrically separated from each other and arranged in rows and columns on one semiconductor substrate; 1. A method for manufacturing an edge-emitting optical semiconductor device, comprising a semiconductor wafer manufacturing process including a step of forming a light reflecting surface at an end of each adjacent element so as to face an output surface.