JPS63129684A - Manufacture of semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To make a high resistance layer good quality and to form a good current blocking structure by growing a compound semiconductor high resistance layer on the flat ground of a one conductivity type compound semiconductor substrate. CONSTITUTION:Semiconductor layers which include a compound semiconductor high resistance layer 2 and a one conductivity type compound semiconductor impurity supply layer 3 are formed on a one conductivity type compound semiconductor substrate 1. Stripes are formed by mesa etching from the surface of the semiconductor layers reaching to the high resistance layer 2. Then, compound semiconductor buried layers 8, 9 are formed on both sides of the stripes, an impurity is diffused from the impurity supply layer 3 to the high resistance layer 2 and selectively made conductive and electrodes 11, 12 are provided by forming a one conductivity type made conductive region 10. By this process, the good quality high resistance layer 2 is obtained since the ground is flat and a good current blocking structure wherein almost no leakage current is generated can be formed.

Description

[Detailed Description of the Invention] [Summary] The present invention provides a method for manufacturing a semiconductor light emitting device, in which required semiconductor layers such as a compound semiconductor high resistance layer and a one conductivity type compound semiconductor impurity supply layer are formed on a one conductivity type compound semiconductor substrate. A high-quality compound semiconductor high-resistance layer is formed by forming a stripe-shaped compound semiconductor impurity supply layer of one conductivity type and diffusing impurities into the compound semiconductor high-resistance layer to selectively make the layer conductive. A buried current blocking structure can be formed, and a high speed and high output semiconductor light emitting device can be obtained.

[Industrial application field]

The present invention relates to an improvement in a method for manufacturing a semiconductor light emitting device having a buried current blocking structure made of a high resistance layer.

[Conventional technology]

Normally, in a semiconductor laser, it is necessary to confine light as well as current, and a pnp structure to which a reverse bias voltage is applied is used to confine the current.

However, there is a limit to the confinement of current due to this, and the flow of leakage current is unavoidable.
Since capacitance is inherent in a junction, when a high frequency is applied for high-speed modulation, leakage occurs through the capacitance.

Furthermore, when the temperature rises or a large current flows, the leakage current increases, so there is a drawback that high output cannot be obtained.

In order to eliminate such drawbacks, semiconductor lasers have been realized in which a high resistance layer is embedded in a portion other than the desired current path.

FIG. 5 shows a cutaway front view of essential parts for explaining a conventional semiconductor laser having a buried current blocking structure made of a high resistance layer.

In the figure, 21 is an n-type 1nP substrate, and 22 is an n-type InP substrate.
Cladding layer, 23 is InGaAsP active layer, 24 is p-type 1nP cladding layer, 25 is InP high resistance layer, 26 is 5T
o2 film, 27 indicates a p-side electrode, and 28 indicates an n-side electrode.

The InP high resistance layer 25 in this conventional example is grown by chloride vapor phase epitaxial growth (chloride vapor phase epitaxial growth).
r phase epitaxy: chlorid
It is formed by applying the VPE method.

Figure 6 is a cutaway front view of essential parts for explaining another conventional example of a semiconductor laser, and symbols used in Figure 5 indicate the same parts or have the same meanings. shall be taken as a thing.

In the figure, 29 indicates an InP high resistance layer.

The InP high resistance layer 29 in this conventional example is formed by metalorganic chemical vapor deposition (metalorganic chemical vapor deposition).
l vapor deposit ion:
It is formed by applying the MOCVD method.

[Problem that the invention seeks to solve]

In the semiconductor laser explained with reference to FIG. 5, it is necessary to form a groove reaching from the surface to the substrate and form a high-resistance layer in the groove, but the technology for this has not been established at present, so it is difficult to obtain satisfactory characteristics. cannot be obtained with good reproducibility.

In the semiconductor laser shown in FIG. 6, the quality of the high resistance layer is better than that described with reference to FIG. 5, but there is a drawback that the surface is not flat.

The present invention aims to provide a semiconductor light emitting device having a buried current blocking structure made of a high-quality high-resistance layer.

[Means for solving problems]

Conventionally, a technology has been established to grow an extremely high-quality, high-resistance layer as long as the underlying layer is flat, so if this technology is effectively utilized, it should be possible to obtain a buried current blocking structure with low leakage current. It is.

Therefore, in the semiconductor light emitting device according to the present invention, a compound semiconductor high resistance layer (for example, InP high resistance layer 2) and a one conductivity type compound semiconductor Impurity supply layer (e.g. p+ type I
a step of growing various semiconductor layers including the nP impurity supply layer 3), then a step of performing mesa etching from the surface of the various semiconductor layers to the compound semiconductor high resistance layer to form a stripe portion; Compound semiconductor buried layers (for example, n-type [nP buried layer 8 and p-type InP buried layer 9) are formed on both sides of the striped portion, and impurities are introduced into the compound semiconductor high resistance layer from the one conductivity type compound semiconductor impurity supply layer. The structure includes a step of diffusing to form a conductive region of one conductivity type (for example, a p-type thick conductive region 10).

[Effect]

By adopting the above-mentioned method, the high-resistance layer can be of extremely high quality because the underlying layer is flat, and a good current blocking structure is formed in which almost no leakage current occurs under any conditions. In addition, impurities are automatically diffused into the high resistance layer from the striped impurity supply layer thereon to selectively form conductive regions, thereby allowing a sufficient current to flow.

Therefore, it is possible to constantly output high output by passing a large current through the fabricated semiconductor light emitting device. Also, unlike a pn junction, there is no capacitance, so there is no leakage even when high frequencies are passed, and therefore high speed is possible. Modulation is possible.

〔Example〕

FIGS. 1 to 4 are cutaway front views of essential parts of a semiconductor laser at key points in the process for explaining one embodiment of the present invention. The explanation will be given below with reference to these figures.

Refer to FIG. 1 (1) For example, by applying the MOCVD method, an InP high resistance layer 2, a p1 type 1nP impurity supply layer 3, and a p-type 1nP buffer/cladding layer 4 are formed on the p-type InP substrate 1. , InGaAsP
An active layer 5 and an n-type InP cladding layer 6 are grown. In this case, in addition to the MOCVD method, VP
E method or 0 is molecular beam epitaxial growth (molecular beam epitaxial growth).
A technique such as the ar beam epi taxy (MBE) method can be appropriately selected and used.

An example of the main data of each semiconductor layer in this case is as follows.

(a) Impurity concentration for substrate 1: 5 x 10'? (cm-”)(b
) Thickness for high resistance layer 2: O, S [μm] ~ Technique [μm] Ic) Thickness for impurity supply layer 3: 0.5Cμm] Impurity concentration: 2×1018 (bell-3) (d) Buffer and cladding layer About 4 Thickness: 0.
5Cμm] Impurity concentration: 5 X 10” (cab-’) (e
) Thickness of active layer 5: 0.15 (μm) (f) Thickness of cladding layer 6 = 2 [μm] Impurity concentration: 5 × 10I7 (cm-”Esee Figure 2) (2) Normal photo By applying a resist process in lithography technology and an appropriate etching method, mesa etching is performed from the surface to reach the high resistance layer 2 to form a stripe portion.

(3) By applying the VPE method, an n-type 1nP buried layer 8 and a p-type 1nP buried layer 8 are formed on both sides of the mesa-shaped stripe part.
A buried layer 9 is formed.

At this time, for example, heat at a temperature of 650 ('C) is applied, so p-type impurities are diffused from the striped impurity supply layer 3 to the high-resistance layer 2, and a p-type warm electrification region 10 is formed.
The stripe portion and the substrate 1 are electrically connected.

Incidentally, the impurity concentration in the p-type warm electrification region 10 is 5×10
It is about 17 (am-').

Refer to FIG. 4 (4) By applying a vacuum evaporation method, the p-side electrode 11 and the n-side electrode 12 are formed.

Examples of the main data of these electrodes 11 and 12 are as follows.

(al Material for electrode 11: A u G e / A u thickness: 1000 (people) / 3 (μm) (b) Material for electrode 12: T i / P t / A u thickness: 100
0 (people)/1000 (people)/3 [μm] [Effects of the Invention] In the method for manufacturing a semiconductor light emitting device according to the present invention, a compound semiconductor high resistance layer and a one conductivity type compound semiconductor substrate are formed on a one conductivity type compound semiconductor substrate. A required semiconductor layer such as a type compound semiconductor impurity supply layer is formed, and impurities are diffused from the striped one conductivity type compound semiconductor impurity supply layer into the compound semiconductor high resistance layer to selectively make it conductive. There is.

By adopting the above structure, the high resistance layer has a flat base, so it can be of extremely high quality, and forms a good current blocking structure in which almost no leakage current occurs under any conditions. In addition, impurities are automatically diffused into the high resistance layer from the striped impurity supply layer thereon to selectively form conductive regions, thereby allowing a sufficient current to flow.

Therefore, it is possible to constantly output high output by passing a large current through the fabricated semiconductor light emitting device. Also, unlike a pn junction, there is no capacitance, so there is no leakage even when high frequencies are passed, and therefore high speed is possible. Modulation is possible.

[Brief explanation of the drawing]

1 to 4 are cut-away front views of essential parts of a semiconductor laser at important process points for explaining one embodiment of the present invention, and FIGS. 5 and 6 are cut-away front views of essential parts of a conventional example. each represents. In the figure, 1 is a substrate, 2 is a high resistance layer, 3 is an impurity supply layer, 4 is a buffer/cladding layer, 5 is an active layer, 6 is a cladding layer, 8 and 9 are buried layers, 10 is a conductive region ,1
1 and 12 indicate electrodes, respectively. Patent Applicant Fujitsu Ltd. Representative Patent Attorney Akira Aitani Representative Patent Attorney Hiroshi Watanabe - Fig. 1 Fig. 2 Fig. 3 Fig. 4 Cutaway front view of main parts of conventional example Fig. 5

Claims (1)

[Claims] A step of growing semiconductor layers including a compound semiconductor high resistance layer and a one conductivity type compound semiconductor impurity supply layer on a compound semiconductor substrate of one conductivity type; forming a stripe portion by performing mesa etching that reaches the compound semiconductor high resistance layer, and then forming a compound semiconductor buried layer on both sides of the stripe portion and removing the compound semiconductor layer from the one conductivity type compound semiconductor impurity supply layer. 1. A method of manufacturing a semiconductor light emitting device, comprising the step of diffusing impurities into a resistance layer to form a conductive region of one conductivity type.