JPS6197888A - Manufacture of photosemiconductor device - Google Patents

Abstract

PURPOSE:To form mirrors flat and vertical in an optical meaning by a method wherein a wafer with a mask film covering the necessary part is tentatively fixed to a rotary table and then etched by irradiation with reactive ions or the like from the oblique direction while the rotary table is rotated on the axis of the direction parallel with the tentative-fixing surface. CONSTITUTION:Covered with a photo resist film 4 over the photosemiconductor element, a wafer 3 is tentatively fixed on the rotary table 1. While a rotary shaft 2 fixed to the side surface of the rotary table 1 is rotated in the direction of an arrow 6, reactive ion beams 5 are made obliquely incident at an angle of phi to the surface of the wafer 3. Streaks are produced on the mirror surface 7 when the surface of the wafer 3 is almost opposed to the reactive ion beams 5, but as the wafer 3 rotates away off that state, the beams 5 come into irradiation from the side surfaces of the streaks and cut them away; the flat surface of the mirror surface 7 improves. Besides, suitable adjustment of the angle phiof incidence of the beams 5 improves the verticality of the mirror surface 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing an optical semiconductor device in which a light emitting surface of a semiconductor laser, an edge-emitting light emitting diode, etc. is formed by etching.

[Conventional technology]

In recent years, development and research on optical integrated circuits has been active.
In that case, a semiconductor laser is naturally incorporated into the optical integrated circuit.

Generally, the mirror surface (laser end face) in an individual type semiconductor laser is formed between folds, and at present,
The mirror surface obtained by this technique shows the best performance.

However, in the case of optical integrated circuits, semiconductor elements having other functions in addition to the semiconductor laser are monolithically integrated.

Therefore, if the interfold technology applied to individual type semiconductor lasers is used for such optical integrated circuits, the substrate will be separated, so it is either impossible to implement, or it is impossible to use a very small-scale device. I can only get it.

Therefore, the mirror surface of the semiconductor laser is subjected to reactive ion etching (reactive ion etching).
Attempts have been made to apply dry etching methods such as (RIE) or wet etching methods using chemical mixtures, etc., but it has not been possible to obtain a high-quality mirror surface, such as that obtained with pleats. I can't.

FIG. 2 shows an explanatory view of the main parts of a sample and an apparatus for explaining the conventional technique of forming a mirror surface by dry etching.

In the figure, 1 is a rotating table, 2 is a rotating shaft, 3 is a wafer on which an optical semiconductor device is fabricated, 4 is a photoresist film, 5 is a reactive or non-reactive ion beam, and 6 is a rotating direction. Each indicates a pointing arrow.

In this conventional technique, the optical semiconductor elements on the wafer 3 are covered with a photoresist film 4, and the wafer 3 is placed on the rotary table 1.
The rotating table 1 and therefore the wafer 3 are rotated as indicated by the arrow 6 while reactive ions are irradiated.
Etching is performed by irradiating the beam 5, and a mirror surface is formed by removing the portion indicated by the broken line in the wafer 3.

FIG. 3 shows a cut-away oblique view of essential parts of a semiconductor laser in which a mirror surface is formed by the technique explained in connection with FIG. 2, and the same parts as those explained in connection with FIG. 2 are indicated by the same symbols.

In the figure, 7 indicates a mirror surface, and 8 indicates a striped electric wire.

As can be understood from the foregoing, when the prior art described with reference to FIG. 2 is applied, a large number of streaks are formed on the mirror surface 7, as seen in FIG. 3.

[Problem that the invention seeks to solve]

The main reason why a large number of streaks are formed on the mirror surface 7 formed by the conventional technique is that the shape of the end face of the photoresist film 4, which is a mask film, is directly transferred to the wafer 3. With this conventional technique, it is impossible to obtain optical flatness and verticality of the mirror surface 7. As explained with reference to FIG. 2, rotating the rotary table 1 on which the wafer 3 is temporarily fixed can only serve to alleviate the non-uniformity of the reactive ion beam 5. Furthermore, it is well known that the edges of the photoresist film 4 as described above have irregularities of about 1000 [people].

The present invention employs a very simple technique when forming a mirror surface of an optical semiconductor device by an etching method, thereby eliminating any streaks that would otherwise be formed on the mirror surface obtained by implementing the conventional technique, and thereby eliminating optical To make it possible to form a mirror surface that is vertically flat and vertical.

Means for Solving Problem c] In the method for manufacturing an optical semiconductor device of the present invention, a mask film such as a photoresist film that covers the optical semiconductor elements and other necessary parts in a wafer in which various elements are fabricated is provided. form,
Next, the wafer is temporarily fixed by pasting it on a rotating table, and then the rotating table is rotated about a direction parallel to the surface on which the wafer is temporarily fixed, and the wafer is attached at an angle to the surface of the wafer. A mirror surface of the optical semiconductor element is formed by performing etching by irradiating reactive ions or the like from a certain direction.

[Effect]

According to the above means, the streaks that would normally occur on the mirror surface of an optical semiconductor element are scraped off from the sides by ions, depending on the relationship between the direction of ion irradiation and the rotation direction of the wafer, and as a result, , the mirror surface is optically flat and vertical.

Embodiment C] FIG. 1 shows an explanatory diagram of the main parts of a wafer and an etching apparatus at key points in the process for explaining one embodiment of the present invention.
The same parts as those described with reference to the figures and FIG. 3 are indicated by the same symbols.

In this embodiment, the rotating shaft 2 is fixed to the side surface of the rotating table 1,
It is designed to rotate in the direction of arrow 6.

Therefore, the wafer 3 temporarily fixed to the surface of the rotating table 1 is etched every time the rotating shaft 2 rotates by 180 degrees.

In the figure, the reactive ion beam 5 is irradiated perpendicularly, but since the rotation axis 2 and therefore the rotary table 1 are set at an angle, the reactive ion beam 5 is irradiated at an angle of φ with respect to the surface of the wafer 3. This means that it is incident on . The wafer 3 is attached to the front and back sides of the rotary table l, but this is for the purpose of increasing work efficiency and is not essential.

When forming the mirror surface 7 of an optical semiconductor element as described above, streaks are generated on the mirror surface 7 at a position where the surface of the wafer 3 is substantially opposed to the reactive ion beam 5. As the reactive ion beam 3 rotates, the reactive ion beam 5 is irradiated from the side of the nucleus and is scraped off, so the flatness of the mirror surface 7 becomes good, and the incident angle of the reactive ion beam 5 By appropriately adjusting φ, the verticality of the mirror surface 7 can also be improved.

In the above embodiment, a flat plate-shaped rotary table 1 was used, but the rotary table 1 is not limited to this, and mass productivity can be improved by using a polygonal column-shaped one such as a triangular prism, a quadrangular prism, etc. do.

In the above embodiment, when the optical semiconductor device assembled on the wafer 3 is a Ga A (l A s / Ga As type double hetero structure semiconductor laser), the photo resist film 4 serving as a mask film is As a result of experiments using a positive type and argon (Ar) ions with an acceleration voltage of 500 (V) as ions to be irradiated, a flat and vertical mirror surface 7 was obtained at φ=15°, and the dark value The current was almost the same as that of the mirror surface between the folds.

〔Effect of the invention〕

In the method for manufacturing an optical semiconductor device of the present invention, a mask film such as a photoresist film is formed to cover the optical semiconductor elements and other necessary parts of a wafer in which various elements are fabricated, and then , the wafer is temporarily fixed by pasting it on a rotating table, and then the rotating table is rotated about a direction parallel to the surface on which the wafer is temporarily fixed, and the wafer is attached in a direction oblique to the surface of the wafer. The mirror surface of the optical semiconductor element is formed by etching by irradiating reactive ions or the like.

In this way, although streaks will be generated on the mirror surface at positions where the wafer surface is approximately opposite to the ion irradiation direction,
From this state, as the wafer rotates, the ions begin etching by scraping away the core from the sides, and as a result, the flatness of the resulting mirror surface is significantly improved.
In addition, by adjusting the direction of ion irradiation to the wafer, it is possible to improve the perpendicularity of the mirror surface, and it is possible to improve the perpendicularity of the mirror surface, so that the characteristics of the mirror surface are almost the same as those of the mirror surface produced by ordinary folds. Good characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the main parts of a wafer and etching apparatus for explaining one embodiment of the present invention, FIG. 2 is an explanatory diagram of the main parts of a sample and etching apparatus for explaining the conventional technique, and FIG. 3 is an explanatory diagram of the main parts of the etching apparatus for explaining the conventional technique. Each of the drawings shows a cut-away oblique view of a main part of a semiconductor laser to explain the mirror surface formed by the technique. In the figure, 1 is a rotating table, 2 is a rotating shaft, 3 is a wafer, and 4 is a rotating table.
is a photoresist film which is a mask film, 5 is a reactive ion beam, 6 is an arrow indicating the rotation direction of the rotation axis 2, 7 is a mirror surface of a semiconductor laser, 8 is a stripe electrode, φ is a reactive ion beam 5 are shown, respectively. . Figure 2 Figure 3

Claims (1)

[Claims] A mask film is formed to cover the optical semiconductor elements and other necessary parts on the wafer in which the various elements have been fabricated, and then,
The wafer is temporarily fixed on a rotary table, and then, while the rotary table is rotated about a direction substantially parallel to the surface on which the wafer is temporarily fixed, ions are irradiated from an oblique direction onto the surface of the wafer. 1. A method for manufacturing an optical semiconductor device, comprising the step of forming a mirror surface of an optical semiconductor element.