JPS58222581A - Manufacture of semiconductor light-emitting element - Google Patents

Abstract

PURPOSE:To simplify the manufacturing process as well as to cut down the cost of production for the titled light-emitting element by a method wherein a P type current blocking layer is thinly formed at the top part of the protrusion of a semiconductor substrate, whereas the current blocking layer is thickly formed on the region other than the protrusion, the component proportionate to the thickness of the P type current blocking layer located at the top part of the protrusion is dissolved, and a current path is completed by conneting an N type semiconductor substrate to an N type clad layer at the top part of the protrusion. CONSTITUTION:A protrusion II, to be used as a current path, is formed on an N type semiconductor substrate 1. Then, a P type current blocking layer 2, an N type clad layer 3, a P type active layer 4 and a P type clad 5 are successively grown. The P type current blocking layer 2 is thinly formed at the top part of the protrusion II of the semiconductor substrate 1, the layer is thickly formed in thickness on the part III which is the region other than the protrusion II. The surface part 6 of the P type current blocking layer 2 is dissolved in the amount of the component of the thickness of the P type current blocking layer 2 using an unsaturated N type clad growing solution. The layer after the N type clad layer 3 are grown after the above dissolution has been finished by lowering the temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor light emitting device, and more particularly to a manufacturing method effective for confining a current flowing inside the semiconductor light emitting device to a specific region.

In general, in a semiconductor light emitting device, confining the current flowing inside the semiconductor light emitting device to a specific region is an essential condition for maintaining and improving its light emitting characteristics.

For example, in laser diodes, it is only possible to reduce the threshold current and achieve transverse fundamental mode oscillation by confining the current into a striped region, and in light emitting diodes, for example, by narrowing the current into a circular region. High brightness can be achieved by narrowing the current.

Conventionally, various structures for current confinement have been proposed, but one of them is a structure that has a junction that is reverse biased during operation because it is difficult to easily block current in the reverse biased junction region. This makes it possible to reliably constrict the current to a specific region, and it is widely used in semiconductor light emitting devices. A cross-sectional view of the main parts of an example of such a semiconductor light emitting device is shown in FIG. In Figure 1, +
11 is an N-type semiconductor substrate, (2) is a P-type flow blocking layer, (3
) is N-type rad layer, (4) is P-type active i, +5+ is P
The three layers of the N-shaped rad layer (3), the P-type active layer (4), and the P-shaped rad layer (5) form a so-called double heterostructure. In this semiconductor light emitting device, during forward biased operation, P type N flow /! ! f21. ? Since the PN junction formed with the n-type cladding layer (3) is reverse biased, the current can be narrowed to the area of the N-type cladding layer (31) surrounded by the P-type current blocking layer (2). Since the width of the light emitting part is carved to a value roughly close to the width W of the area, laser diodes can achieve reduced threshold current, oscillation in the transverse fundamental mode, etc. However, at this time, in order to prevent the P-type current blocking layer (2) from absorbing the light generated in the P-type active layer (4), generating carriers and collapsing the blocking state, the P-type current blocking layer (2) must be It is necessary to take measures such as making the forbidden band width of the P-type current blocking layer (2) larger than that of the P-type active layer (4).

FIGS. 2(a) to 2(c) show cross-sectional views of main steps in the conventional manufacturing method of the semiconductor light emitting device shown in FIG. 1. First, as shown in Figure 2 (,), an N-type semiconductor substrate (
1) Grow P-type city, flow prevention N(2) on top. Next, as shown in FIG. 2(b), a window is formed in the P-type current blocking layer (2) in the area that should become a current path by photolithography.
Next, as shown in FIG. 2(C), an N-shaped rad layer (
3), a P-type active layer (4), and a P-type rad m (51) are grown to complete the device structure.In the conventional manufacturing method, as shown in FIG. Because the window opening process in #(2) is required, the crystal growth must be performed in two steps, which increases the complexity of the process and the length of time required to manufacture the device, which in turn increases the manufacturing cost. Furthermore, in GaAs-based semiconductor light emitting devices, the P-type current blocking (2) is used to widen the forbidden band.
Although it is formed of lGaAe, this AI! Because GaAe has strong oxidizing properties, it is necessary to treat and handle the crystal substrate very carefully before the second crystal growth to form a double heterostructure, but even then, aluminum oxide often remains or is generated. During the second crystal growth, some parts of the crystal do not grow due to this aluminum oxide, and even after the device structure is completed, the crystal parts that incorporate the aluminum oxide have defects and become non-emissive parts, causing the device to fail. There were some disadvantages to manufacturing yields, such as shortening the lifespan.

The present invention has been made in view of the above points, and aims to simplify the manufacturing process and reduce manufacturing costs in a method of manufacturing a semiconductor light emitting device. The purpose is to improve crystallinity and improve manufacturing yield by simplifying the manufacturing process.

In order to achieve the above object, this invention
A protrusion to serve as a current path is provided on a semiconductor substrate, and a P-type current blocking layer, an N-type rad layer, a P-type active layer, and a P-type rad layer are grown by one-time liquid phase epitaxial growth to form a device. To complete the structure, a P-type current blocking layer is grown to be thinner on the top of the protrusion of the semiconductor substrate and thicker in areas other than the protrusion.
In the next growth of the N-shaped rad layer, the surface of the P-type current blocking layer is dissolved by an amount corresponding to the thickness of the P-type current blocking layer on the top of the protrusion, and the N-type semiconductor substrate is formed at the top of the protrusion. The current path is completed by connecting the N-shaped rad layer.

FIGS. 3(a) and 3(b) show cross-sectional views of main steps in an embodiment of the method for manufacturing a semiconductor light emitting device according to the present invention. First, as shown in FIG. 3(a), a protrusion (2) to serve as a current path is formed on the N-type semiconductor substrate (1+) by photolithography. Next, as shown in FIG. 3(b), a P-type current blocking layer (
2 to N-type rad layer (3), P-type active layer (4) and P
A shaped rad layer (6) is grown continuously.

At this time, the P-type current stop N (2) is made thinner on the top of the protruding part (■) of the semiconductor substrate (1), and the layer thickness is made thinner on the top of the protruding part (■) of the semiconductor substrate (1),
Thick layer of moss - Make it grow thick. In this case, for example, GaA
In the s-based semiconductor light emitting device, the P-type lightning, and the flow blocking layer (2) is P-type lightning.
Aj+G to widen the υ forbidden band width as in shape active skin (4)
However, in the growth method where the temperature is lowered with a constant temperature gradient, the cooling rate is kept very low, less than 1°C/min, so that an AlGaAs layer can be grown on the uneven surface with the layer thickness distribution shown above. It is widely known that it is possible to The P-type current blocking layer (2) grown in this way is covered with an unsaturated N-type rad growth solution, and the P-type current-blocking layer (2) is coated with an amount corresponding to the thickness of the P-type current blocking layer (2) grown on the top of the protrusion. The surface portion (6) of the current blocking layer (2) may be dissolved. The amount to be dissolved is determined by adjusting the degree of unsaturation depending on the amount of arsenic in the solution for growing the N-shaped rad layer (3). Also,
As for the dissolving method, just cover the P-type current blocking layer (2) with a saturated solution for growing the N-type LAD layer (3), and then raise the temperature to grow the N-type LAD layer (3). Of course, it is also possible to use the method of making the solution unsaturated and dissolving the surface of the P-type layer or flow prevention layer (21).In this case, the amount dissolved can be adjusted depending on the temperature increase Often, the layers after N-shaped rad Jitl (31) can be grown by lowering the temperature again after melting.

As mentioned above, 1. According to the present invention, the crystal growth that conventionally required two times can be reduced to just one, so that it is possible to shorten the manufacturing period and reduce the manufacturing cost by simplifying the manufacturing process. Furthermore, in the case of one-time crystal growth, unlike in the case of two-time growth, there is no need to take the crystal growth substrate out of the growth furnace and expose it to the outside air after the first growth. With AlGaAs, there is no need to worry about oxidation due to outside air, so improvement in crystallinity can be expected, and manufacturing yield can be improved.

In addition, although the above-mentioned embodiment describes an AlGaAs-based semiconductor light-emitting device, it is equally effective when using other semiconductor materials, such as indium phosphide (Ink)-based materials. It's not even close to saying that.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing an example of a semiconductor light emitting device having a current blocking suit using a reverse bias junction, Fig. 2 (8) to (0)
is a cross-sectional view showing the main steps of the conventional manufacturing method for the semiconductor light emitting device shown in FIG. 1, and FIG. 3<a), (1)
) is a sectional view showing the main steps of an embodiment of the method for manufacturing a semiconductor light emitting device according to the present invention. In the figure, fl+ is an 11-type semiconductor substrate, (2) is a P-type current blocking/ai (first semiconductor layer), (31 is an N-type rad layer (second semiconductor layer), and f41 is a P-type active layer). , (5) is P-type rad scrap, (6) is P-type current blocking layer (
2), the melt penetration part, J is the area that should become a current path, n is the protrusion of the N-type semiconductor substrate (1), 111 is the part other than the protrusion of the semiconductor base & (1), W is the protrusion This is the width of the area that should become the current path for the part. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Makoto Kuzuno - (1 other person) Figure 1 Figure 2 Figure 3 Procedural amendment (voluntary) Commissioner of the Japan Patent Office], 0 items displayed Patent Application No. 106420/1982
, Title of the invention Method for manufacturing semiconductor light-emitting devices 3, Relationship to the amended case Patent applicant address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Jinhachi Katayama, Representative of Mitsubishi Electric Corporation Part 4, Address of agent: 2-2-3-5 Marunouchi, Chiyoda-ku, Tokyo, Subject of amendment 8A#I, Claims column and Detailed explanation of the invention column 6, Contents of amendment (1) The scope of claims in the specification shall be corrected as per the attached appendix. (2) "GaAs-based" on page 4, line 16 and page 6, line 18 of the specification is corrected to "AAGaAs-based." (3) Same, on page 4, line 17, "P-type current blocking layer (2)" is corrected to "P-type current blocking layer (2)". 7. List of attached documents (1) Documents showing the scope of the claims after correction One or more copies Patent l1 Scope of Ti water (1) A first semiconductor substrate provided on a semiconductor substrate and having a conductivity type opposite to that of the semiconductor substrate A PH junction formed between a semiconductor layer and a second semiconductor layer provided at a predetermined position on the first semiconductor layer and having the same conductivity type as the semiconductor substrate is reverse biased during operation to block current flow. In a method for manufacturing a semiconductor light emitting device having a structure, a protrusion for confining a current is formed in advance on one main surface of the semiconductor substrate, and the semiconductor substrate having the protrusion is grown by a liquid phase epitaxial growth method. The first semiconductor layer is formed on the main surface of the semiconductor layer such that the first semiconductor layer is thin at the top of the protrusion and thick at areas other than the protrusion;
A method for manufacturing a semiconductor light emitting device, characterized in that the second semiconductor layer is formed on the semiconductor layer in such a way that the first semiconductor layer r/iS on the top of the protruding portion dissolves and disappears.

Claims (1)

[Claims] (1) A first semiconductor layer provided on a semiconductor substrate and having a conductivity type opposite to that of the semiconductor substrate; and a first semiconductor layer provided at a predetermined position on the first semiconductor layer and having the same conductivity type as the semiconductor substrate. In a method for manufacturing a semiconductor light emitting device having a structure in which a PN junction formed with a second semiconductor layer is reverse biased during operation to block current, a protrusion for confining current on one main surface of the semiconductor substrate is provided. is formed in advance on the main surface of the semiconductor substrate having the protrusion by liquid phase epitaxial growth so that the layer is thin at the top of the protrusion and thick at areas other than the protrusion. The first semiconductor layer is formed on the first semiconductor layer, and the second semiconductor layer is formed on the first semiconductor layer such that the first semiconductor layer on the top of the protrusion is dissolved and disappeared. A method for manufacturing a semiconductor light emitting device, characterized in that: