JPH06101609B2 - Method for manufacturing semiconductor laser device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor laser device in which a plurality of semiconductor light emitters are monolithically formed.

[Conventional technology and problems]

Conventionally, when an optical scanning device is designed by using a plurality of semiconductor lasers or light emitting diodes (LEDs) as disclosed in, for example, Japanese Patent Laid-Open No. 59-186, as shown in FIG. The light sources are arranged so that the emission directions of the two intersect at a single point P ₀ , and a plurality of scanning spots are devised so that the surface to be scanned (not shown) can be scanned while maintaining a good image formation state.

FIG. 7 shows a typical conventional example, and is a view of an optical system between a light source and a deflector as seen from a direction perpendicular to a deflection scanning plane. Reference numerals 71a and 71b are semiconductor lasers, and each laser is arranged on the mount 72 such that its light flux generating surface is parallel to the end surface of the mount 72. Semiconductor laser 71a, 71
The end faces 72a, 72b of the mount 72 provided with b are at the point P ₀ where the central rays ha, hb of the divergent light beams from the lasers 71a, 72b are the same.
It is set as if it came through. In other words, at the positions where the semiconductor lasers (71a, 71b) are provided, the end faces 72a and 72a
The end faces 72a and 72b are set so that when normal lines are set on b, the normal lines pass through P ₀ . Further, when viewed from a direction parallel to the deflection scanning plane, the mounts 72 are arranged so that the positions of the center rays ha and hb of the respective semiconductor lasers passing through the point P ₀ are slightly displaced in the direction orthogonal to the deflection scanning plane. The position of the semiconductor laser provided above is set. The point P ₀ and a point P in the vicinity of a predetermined position on the deflecting / reflecting surface 78 of the deflector are kept in an optically conjugate relationship by the imaging lens 74.

As described above, in order to arrange a plurality of semiconductor light emitters (for example, semiconductor lasers) so that the light emitting directions thereof are different from each other, as shown in the above example, they are aligned on the mount to form a hybrid structure. Had to do. For the sake of convenience, the term array laser is used as a plurality of semiconductor light emitters, but in principle it also applies to light emitters such as LED arrays.

When using a monolithically formed array laser, it is necessary to install some optical system in front of the array laser. In the example disclosed in JP-A-58-211785, a prism is arranged in front of the array laser. This is shown in FIG.

FIG. 8 shows a cross section of a prism when the semiconductor array laser has five light emitting portions. Reference numeral 81 is a semiconductor array laser having five light emitting portions (81a, 81b, 81c, 81d, 81e), and 82 is a prism. The central ray ha of the light flux from the light emitting portion 81a is refracted by the inclined surface 82a and bent as if it had passed through P ₀ . Similarly, the central ray hb from 81b is bent by the inclined surface 82b, the central ray hd from 81d is bent by the inclined surface 82d, and the central ray he from 81e is bent by the inclined surface 82e, respectively, as if they had passed through P _0. To be The central ray hc from 81c passes through the plane 82c vertically, and P ₀ exists on the extension line of the central ray hc. In this way, an inclined flat surface having an inclined angle determined corresponding to each light emitting portion is provided, and the central ray of each light flux after exiting the prism 82 is controlled in its direction as if it exited from P _0. There is. As described above, this P ₀ is kept conjugate with the desired position P (not shown) near the deflecting and reflecting surface via the optical system.

The problems in this case are the fine processing precision and method of the prism 82, the alignment and joining method of the prism 82 and the array laser 81, and the smaller the pitch of the array laser, the more difficult it becomes. In fact, it is almost impossible with 100 μm or less.

On the other hand, FIG. 9 shows an optical system, that is, a relay optical system 93, which is intended to have a similar effect. A collimator lens 92 which collimates the light emitted from the array lasers 91a and 91b to form an image.
In this example, an image is formed on the polygonal surface 94 with a relay system 93 interposed between the cylindrical lens 95 and the cylindrical lens 95, and an image is formed on the surface to be scanned (not shown) in a good image formation state.

The problem in this case is the optical path length, which is about 20 in the relay system itself.
cm becomes longer.

On the other hand, in order to solve the above problems, the present applicant has proposed in Japanese Patent Application Nos. 59-240418 and 60-424 that a plurality of semiconductor lasers are monolithically formed and each semiconductor is We have already proposed a semiconductor device in which the laser emission directions are different.

[Outline of Invention]

It is an object of the present invention to provide a method of manufacturing a semiconductor laser device which can be easily manufactured and can be combined with a lens or the like to form an optical system having a short optical path with high accuracy in a small number of steps.

The above object of the present invention is a method of manufacturing a semiconductor laser device in which a plurality of semiconductor lasers having mutually different light emitting directions are monolithically formed, and an active region of each semiconductor laser is formed on a semiconductor wafer. When forming a plurality of limiting stripe patterns in a predetermined direction substantially perpendicular to the cavity surface of the semiconductor laser, a portion including both stripe patterns of adjacent devices in the predetermined direction is provided. Cleavage is accomplished by forming the resonant surface of the adjacent device in a single cleavage.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to the drawings.

As a method of manufacturing a semiconductor laser, a photolithography process is used to form a photolithography pattern as shown in FIG. 3, and cleavage is performed at A, A ′, A ″, A in the figure to form a resonator surface. There is a possible method of forming it, but between AA ′,
A'A is wasted, and two cleavages are required to form two resonator faces, which leads to a reduction in yield. Therefore, in the present invention, two cleavages are cleaved once. It is formed by.

FIG. 1 is a plan view showing a state of a stripe pattern on a wafer formed by the method of the present invention. 1 in the figure
Reference numeral 1 "denotes individual oblique array lasers each having one portion as one unit, and 2 to 2'represent portions where these lasers overlap each other. 11 to 15 denote individual semiconductor lasers (a- (In the array laser cleaved at A), 11a to 15a correspond to the current injection region, that is, the emission region in each semiconductor laser 11 to 15. And, this injection region 11a.
15b to 15a (hereinafter referred to as resonance direction) 11b to 15b.
And the normals 13 standing on the resonance surfaces 16 and 17 are formed at angles of φa, φb, φc, φd, and φe, respectively.

The resonance planes 16 and 17 are parallel because a cleavage plane of a crystal (for example, GaAs) normally used as a substrate is used, but in the case where there is a possibility that the parallelism is slightly different as in dry etching. Is based on the resonance surface 16 on the front side of the laser emission.

The light resonated at the resonance planes 16 and 17 is resonated as laser light.
When exiting from 16, it is bent according to Snell's law. In the figure, 11c to 15c indicate light emitting directions.

Here, if an angle formed by an arbitrary light emission direction and the normal line 18, that is, an emission angle is θ, a relationship of n / n ₀ = sin θ / sin φ is established. For example, considering the case of emission from a GaAs crystal, n
(Crystal refractive index) is about 3.5, n ₀ (Air refractive index) is about 1
Therefore, if φ is selected to be 1 degree, the laser beam is emitted with an inclination of about 3.5 degrees with respect to the normal line 18.

In this case, the resonance surface is formed as if the light is emitted from the vicinity of a point P ₀ on the opposite side to the emission side.
No additional components such as (Fig. 8) or relay optics 98 (Fig. 9) are required. Then, it becomes possible to realize a light source that can obtain a good image-forming state with an apparatus using a simple scanning optical system. In the figure, 11a to 11c indicate current injection regions.

The distance l between the array lasers and the deviation between the emitting directions θ (θ
_In general, it is convenient for device design to use a constant value for ₁ , θ ₂ ). That is, θ ₁ = θ ₂ , but it does not necessarily have to be a constant value. The relationship between 1 and θ depends on the optical system used, particularly the focal length of the collimator lens 98 shown in FIG.

FIG. 2 is a sectional view taken along the line BB ′ in FIG. Hereinafter, the manufacturing process will be described in detail with reference to this drawing.

First, n-type GaAs was used as the substrate 5. On this n-type GaAs substrate 5, an n-type (Si-doped) GaAs layer 6 of about 2 μm, and subsequently an n-type AlGaAs layer (cladding layer) 7 of 2 μm, non-doped.
0.1 μm GaAs layer (active layer) 8, p-type (Be-doped) AlGaA
s layer (clad layer) 9 is 2 μm, p-type GaAs layer 10 is 0.2 μm
After sequentially growing by the molecular beam epitaxy method, the entire surface is covered with a silicon nitride plasma CVD film. afterwards,
By the usual photolithography process, the current injection region (11a to 15a in the case of an array laser of 1 is arranged so that the laser stripes of 1 and 1'are overlapped as shown by 2-2 'in FIG. (Part) was removed by etching and covered with a laminated electrode 20 of Cr and Au. The electrode 20 is
The individual lasers were separated by the Photolitho Bluffy process so that they could be driven independently (11-15 parts for an array laser). On the back side, a laminated electrode of AuGe and Au 21
After forming, the ohmic was realized by thermal diffusion. As shown by the lines a-a and a'-A ', the laser was cleaved at each unit in the middle of the overlapping portion 2 to form a resonator surface. Then, individual electrodes were taken out by wire bonding.

FIG. 4, FIG. 5, and FIG. 6 are modified examples of the present invention, and all of them are patterns in which both sides can be used as a resonator surface by one cleavage. The sectional views taken along the line BB 'are similar to those in FIG.

Although the stripe electrode type laser (a kind of gain waveguide type laser) using the GaAs system is described as an example in the present embodiment, it is also applicable to other gain waveguide types such as a proton bombard type and a diffusion stripe type. Moreover, it is also effective for a refractive index guided laser such as a BH structure or a Ritz Wave structure. It is also effective for a laser having a substrate-processed structure.

In addition, the materials for the semiconductor laser are GaAs / AlGaAs and In
It goes without saying that the same applies to materials such as P / InGaAsP-based and AlGaInP-based materials. The growth method is similarly effective in the liquid phase epitaxial method and the MOCVD method as well as the molecular beam epitaxy method. In the embodiment, the n-type is used for the substrate, but it is also effective for the P-type, and it is also effective if the n- or P-type GaAs is grown on the semi-insulating substrate.

〔The invention's effect〕

As described above, the present invention is characterized in that an injection region is provided so that a cavity surface common to both sides can be formed by one cleavage in the production of an array laser having different light emission directions. By adopting the laser manufacturing method, the pitch width can be extracted with good reproducibility, and the number of cleavages is reduced (for example, the number of cleavages is halved when comparing Fig. 1 and Fig. 3). Made possible. At the same time, it has become possible to use the semiconductor light emitting wafers with high density.

By using the array lasers having different light emitting directions, laser light from a large number of points can be formed into a good image on a medium by using a scanning optical system, and therefore, as a light source of an optical device such as a laser beam printer. It is extremely advantageous.

[Brief description of drawings]

1 is a plan view showing a pattern on a wafer according to the present invention, FIG. 2 is a sectional view taken along the line BB 'in FIG. 1, FIG. 3 is a plan view showing a normal pattern on a wafer, and FIG. Figure,
5 and 6 are plan views each showing a modified example of the pattern according to the present invention, FIG. 7 is a view showing a conventional example in which a laser is arranged in a hybrid, and FIG. 8 is an array laser and a prism having a constant emitting direction. FIG. 9 is a diagram showing a conventional example in which the emitting directions are made different by combining, and FIG. 9 is a diagram showing a conventional example in the case where an optical system is used to correct an array laser having a constant emitting direction. 1,1 ′, 1 ″ …… Left array laser, 16,17 …… Resonance plane.

Front page continuation (72) Inventor Yoshinobu Sekiguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Seiichi Miyazawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (1)

[Claims] 1. A method for manufacturing a semiconductor laser device comprising monolithically forming a plurality of semiconductor lasers having mutually different light emission directions, wherein an active region of each semiconductor laser is limited on a semiconductor wafer. When forming a stripe pattern for a plurality of devices in a predetermined direction substantially perpendicular to the cavity surface of the semiconductor laser, a portion including both stripe patterns of adjacent devices in the predetermined direction is provided, and this portion is cleaved. By doing so, a method of manufacturing a semiconductor laser device in which the resonance surfaces of the adjacent devices are formed by one cleavage.