JPH02205319A - Manufacture of semiconductor element - Google Patents

Abstract

PURPOSE:To obtain a semiconductor element, a process of which is facilitated and which has excellent reproducibility, by forming an insulating film to a base material as a mask material is left as it is not removed and taking off, the insulating film in the top section of a protrusion together with the mask material. CONSTITUTION:Striped photo-masks 17 are shaped to the upper section of a semiconductor laser wafer, sections up to the upper section of approximately 0.5mum+ or -0.2mum of an active layer 14 are etched through the photo-masks 17, and polyimide LB(Langmuir-Blodgett) films 18 are formed in 200Angstrom as the masks 17 are left as they are and an insulating film is shaped. The films 18 of the top sections of ridges are lifted off by an etchant dissolving only the masks 17, and used as current injection regions. Cr-Au ohmic electrodes are formed through a vacuum deposition method as upper electrodes 102, a GaAs substrate 11 is lapped to thickness of 100mum, and an Au-Ge electrode is evaporated as an N-type ohmic electrode 103. Accordingly, a process can be simplified, and a semiconductor element having excellent reproducibility is acquired.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a semiconductor element having minute protrusions, such as a semiconductor element used in an optical information transmission device.

[Conventional technology]

Conventionally, an alignment method involving mask alignment has been used to remove only the insulating film on the top of the protrusion of a semiconductor element having minute protrusions.

Also, an etch-back method was used. This will be explained with reference to FIG. First, the semiconductor wafer substrate is etched through the mask material 301 so that the pitch of the protrusions is 3 μm, the width of the protrusions is 1 μm, and the depth is 2 μm (Figure 2b).
.

Next, the mask material is removed with a mask material remover and washed (FIG. 2C).

Next, a silicon nitride film 30 is formed using a plasma/CVD method or the like.
A second insulating film is formed (FIG. 2d).

Furthermore, the photomask material 303 is flattened by spinner coating (2nd e).

Next, the entire mask material is etched using a dry etching method until only the tops of the protrusions are exposed.
Then, the insulating film on the top of the projection is etched (FIG. 2g), and finally, the remaining mask material other than the projection is removed (FIG. 2H).

[Problem that the invention is trying to solve]

However, the conventional example described above has the following drawbacks in the process of removing the insulating film only from the top of the protrusion in a semiconductor element having minute protrusions.

First, in the alignment method, 1) When the protrusion width is approximately 3 μm or less, the accuracy of alignment between the wafer and the mask must be approximately 0.5 μm or less, but this is difficult and time-consuming. 2) In addition, the insulating film is likely to be removed not only from the top of the protrusion but also slightly below the top, making control difficult. 3) Since the wafer is brought into contact with the mask, the chipping into the square is difficult. , easy to crack, damage the wafer, shorten the life of the semiconductor element, and have poor reproducibility. 4) Furthermore, if the pitch of the protrusions is 3 μm or less, it cannot be applied due to the grain size of the alignment. There are, etc.

The etch-back method has problems such as 1) poor controllability since not only the top of the protrusion but also the insulating film slightly on the sides are removed, and 2) process steps are long and throughput is poor.

[Means to solve the problem]

An object of the present invention is to provide a method for manufacturing a semiconductor device with an easy process and good reproducibility in manufacturing a semiconductor device having microprotrusions, and to improve the yield of the wafer process and improve the yield of the manufactured semiconductor. This realizes a long life.

In the present invention, a mask material is provided in a desired pattern on a base material, the base material is etched, an insulating film is formed on the base material without removing the mask material, and the protrusions are removed by an etching method in which only the mask material is removed. A method for manufacturing a semiconductor element having a microscopic protrusion, characterized in that the insulating film on the top of the mask is removed together with the mask material, and in particular, the temperature at which the absolute M film is formed is at a temperature at which the mask material does not foam. The above manufacturing method is characterized in that:

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and based on this, the manufacturing process of a ridge type semiconductor laser will be described in detail.

First, 1 μm of n-type GaAs was sequentially deposited as a buffer layer 12 on an n-type GaAs substrate +1 by molecular beam epitaxy.
m, and n-type A1.m as the cladding layer 13. , , Gao. a
As was formed to a thickness of 2 μm. For the active layer 14, 100 people used non-doped GaAs, 30 people used Alo, 2Gao, and aAs, each of which was repeated 4 times, and finally, 1 layer of GaAs was used.
00 layers were stacked to form a multiple quantum well structure. Next, as the cladding layer 15, P type A1. , Gao,
As the cap layer 16, 1.5 μm of As and 0 μm of GaAs.
．． A thickness of 5 μm was formed.

Next, a striped photomask 17 is provided above the semiconductor laser wafer (FIG. 1a), and a reactive ion beam in a chlorine gas atmosphere is applied through the photomask 17 to about 0.5 μm±0.2 μm in front of the active layer. It was etched by etching (Fig. 1b).

Next, leaving the photomask 17, polyimide LB (
Langmuir-Prodgett) @ 18 (Fig. 1 C). Subsequently, the polyimide LB film 18 at the top of the ridge was lifted off using an etching solution that dissolved only the photomask 17, thereby forming a current injection region (1g, 1d).

Furthermore, a Cr-Au ohmic electrode is formed as the upper electrode 102 by vacuum evaporation, and the GaAs substrate is polished to a thickness of 100 μm, and then a u-Ge electrode is deposited thereon as the n-type ohmic electrode 103. Figure 1 e
).

Subsequently, after heat treatment was performed to establish ohmic contact between the P-type and N-type electrodes, a resonant surface was formed by cleavage, separated by a scribe, and the electrodes were taken out by wire bonding. Here, the cavity length is 300
It is μm. Furthermore, Al2
A high reflection film and a low reflection film based on O, -5iO2 were coated.

As a result, the threshold current is 15 mA or less, astigmatism is 4 μm or less, the horizontal and directional beam divergence angle of the far field image exceeds 15 degrees, and the product has a long life (up to 200 mA at room temperature).
A semiconductor laser capable of laser oscillation for more than 0 hours was obtained.

When semiconductor lasers were repeatedly formed using the same process, semiconductor lasers with similar characteristics were obtained with good reproducibility.

Note that the resonant surface may be formed by cleaving, or may be formed on one or both sides of the resonant surface by a wet etching process, a dry etching process, or the like.

The present invention can also be effectively applied to manufacturing distributed feedback type and distributed reflection type lasers.

Furthermore, the present invention can be applied not only to the manufacture of ridge-type semiconductor laser devices having minute protrusions, but also to the manufacture of semiconductor devices such as waveguides, optical switches, and optical modulators having similar protrusions.

Furthermore, the above-mentioned photomask may have a multilayer structure, and the same effect can be obtained by lift-off using a dry process (UV asher, etc.).

Further, the film thickness of the LBI sample described above is effective as long as it can be lifted off by up to several thousand people.

Furthermore, the insulating film may be a polymer film other than the LB film formed by vacuum evaporation, or a spin-coated film.

Examples of the insulating film material used in the present invention include the following.

[1] Diacetylene compound C11,-+CH2')-1nCmiC-G =C-+C
t12Th XO<n, jlj<20 where n+1>10

[11] Addition polymer 1) Polyacrylic acid 6) Vinyl acetate copolymer 2) Polyacrylic ester 3) Acrylic acid copolymer [II [] Condensation polymer 1) Polyamide 4) Acrylic ester copolymer 5) Polyvinyl acetate 2) Polycarbonate [IV] Ring-opening polymer 1) Polyethylene oxide Here, R1 is a long-chain alkyl group introduced to facilitate the formation of a monomolecular film on the water surface, and its carbon number n is 5≦n.
≦30 is suitable. Further, R5 is a short-chain alkyl group, and the number of carbon atoms n is preferably 1≦n≦4. The degree of polymerization m is 10
It is preferable that 0≦m≦5000.

It goes without saying that any organic material or organic polymer material other than those mentioned above is also suitable for the present invention as long as it is suitable for the LB method.

〔Effect of the invention〕

As explained above, according to the present invention, even when the pitch width of the micro-projections is so narrow that alignment cannot be achieved, only the insulating film at the top of the micro-projections can be removed with good control;
The process can also be simplified.

Therefore, it becomes possible to manufacture semiconductor devices with good reproducibility, the yield is improved, and it becomes possible to provide semiconductor elements that are extremely effective for optical information transmission devices.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the steps of the semiconductor manufacturing method of the present invention, and FIG.
The figure is a diagram showing the steps of a conventional semiconductor manufacturing method.

Claims (1)

[Claims] 1) In a method of manufacturing a semiconductor device having minute protrusions, a mask material is provided in a desired pattern on a base material, the base material is etched, and the mask material is etched onto the base material without being removed. 1. A method of manufacturing a semiconductor device, comprising forming an insulating film and removing the insulating film at the top of the protrusion along with the mask material by an etching method that removes only the mask material. 2) The manufacturing method according to claim 1, wherein the temperature at which the insulating film is formed is a temperature at which the mask material does not foam.