JP2659430B2 - Manufacturing method of wavelength stable semiconductor laser - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a wavelength-stable semiconductor laser having an external resonator, and more particularly, to a method for mounting a chip on a package.

<Prior art> A wavelength-stable semiconductor laser includes a semiconductor laser chip (hereinafter, referred to as a laser chip) capable of emitting laser light from a front end face and a rear end face.
An external resonator is constructed by arranging the rear end face of the "LD chip" and the reflecting surface of the mirror chip parallel to each other and separated by a predetermined distance, thereby stabilizing the axial mode of laser oscillation and increasing the laser wavelength. There is something that stabilizes.

Conventionally, as a method of mounting a chip of this kind of wavelength-stable semiconductor laser on a package, there is the following method. First, as shown in FIG. 2A, the LD chip 12 is heated on a die bonding surface 11 of the package with the front end face 12f facing forward, cooled with a brazing material and then die bonded in advance. Then, the upper surface of the mirror chip 13 is
The lower portion of the reflection surface 13m of the mirror chip 13 is brought into contact with the rear end surface 12b of the LD chip 12 from behind while adsorbing 13a. In this case, the reflection surface 13m of the mirror chip 13
Is pressed by the rear end face 12b of the LD chip 12, the mirror chip 13 is slightly displaced while being adsorbed by the collet 14, and the lower part of the reflection surface 13m and the rear end face 12b of the LD chip 12 are in close contact and parallel to each other. Become. Note that the tip end surface of the collet 14 is parallel to the die bonding surface 16, and both the chips 12, 13 are rectangular parallelepiped. ▲ ▼ indicates the die bond surface
The shadow of the mirror chip 13 projected perpendicularly to 16 is shown (similar in FIG. 2 (b)). Next, as shown in FIG. 2 (b), the collet 14 is moved backward to separate the rear end face 12b and the reflecting face 13m by a predetermined distance D while maintaining the parallelism. Then, as shown in FIG. 2 (c), the package is moved by moving the collet 14 downward, fixing the mirror chip 13 by applying a predetermined load to the die bonding surface 11 on which the brazing material is previously spread and pressing the package. The brazing material is melted by heating, and then cooled and hardened, and the mirror chip 13 is die-bonded.

When the collet 14 is removed, as shown in FIG. 2 (d), the two chips 12, 13 are separated by a predetermined distance D in parallel with the rear end face 12b of the LD chip 12 and the reflection surface 13m of the mirror chip 13. In this state, the package is mounted on the die bonding surface 11 of the package.

<Problems to be solved by the invention> However, the above-described conventional chip mounting method is
Since the die bonding of the mirror chip 13 is performed after the die bonding of the LD chip 12, there is a problem that the time required for die bonding is twice and the time required for mounting is long. Further, the LD chip 12 is heated and cooled during die bonding.
There is a problem of receiving the cooling temperature stress twice.
Also, at the time of heating when the mirror chip 13 is die-bonded,
The wax material between the LD chip 12 and the die bonding surface 16 melts and
The tip 12 may be slightly misaligned,
The external resonator composed of the rear end face 12b of the LD chip 12 and the reflection surface of the mirror chip 13 has a problem that the accuracy of the distance D between the resonance surfaces is not good.

Therefore, an object of the present invention is to mount both chips on a package simultaneously with a single die bond, thereby reducing the time required for mounting, reducing the thermal stress on the LD chip, and improving the distance accuracy between the resonance surfaces. It is an object of the present invention to provide a method for mounting a wavelength-stable semiconductor laser chip that can be improved.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a semiconductor laser chip in which a semiconductor laser chip and a mirror chip capable of reflecting laser light are die-bonded on the same surface. A method of manufacturing a wavelength-stable semiconductor laser in which an external resonator is constituted by the laser light emitting surface of the mirror chip and the reflecting surface of the mirror chip, wherein the semiconductor laser chip and the mirror chip are adsorbed by different collets, respectively. Then, after the laser light emitting surface of the semiconductor laser chip and the reflecting surface of the mirror chip are brought into contact with each other in a space other than the die bonding surface, the laser light emitting surface and the reflecting surface are separated by a predetermined distance while maintaining parallelism. To fix the relative positional relationship,
It is characterized in that die bonding is performed simultaneously on the die bonding surface.

<Operation> Since the LD chip and the mirror chip are adsorbed by different collets, both chips can be simultaneously moved to the die bonding surface and die bonded once. If the die bonding is done at the same time, the time required is only one time.
The thermal stress applied to the chip is reduced from the conventional two times to one time.

Further, before performing die bonding, the laser light emitting surface of the LD chip and the mirror surface of the mirror chip are brought into contact with each other,
After the parallelism is given, the die bonding is performed while the relative positional relationship is fixed at a predetermined distance, so that the distance accuracy between the resonance surfaces of the external resonator formed on both sides is improved.

Embodiment Hereinafter, a method for mounting a chip of a wavelength-stable semiconductor laser according to the present invention will be described in detail with reference to the illustrated embodiment.

First, as shown in FIG. 1 (a), the upper surface 2a of the LD chip 2 capable of emitting laser light forward and backward is placed on a collet 4
On the other hand, the upper surface 3a of the mirror chip 3 having the reflecting surface 3m capable of reflecting the laser beam is sucked by another collet 5, and both chips 2, 3 are positioned above the die bonding surface 1 of the package. The front end face 2f of the LD chip 12 is directed forward, and the reflection surface 3m of the mirror chip 3 is opposed to the rear end face 2b. The tip surfaces of both collets 4 and 5 are parallel to the die bonding surface 1, and
Each of the two chips 2 and 3 is a rectangular parallelepiped. ,
Is the LD chip projected perpendicular to the die bonding surface 6
2, showing the shadow of the mirror chip 3 (FIG. 1 (b),
(The same applies to (c).)

Next, as shown in FIG. 1 (b), the collet 5 is moved forward with the collet 4 still, and the reflecting surface 3m of the mirror chip 3 is brought into contact with the rear end surface 2b of the LD chip 2 from behind. Let it. In this case, the LD chip 2 and the mirror chip are slightly shifted while being attracted to the collets 4 and 5, respectively, and the rear end face 2b and the mirror face 3m are closely contacted and parallel to each other.

Subsequently, as shown in FIG.
The collet 5 is moved rearward while keeping the stand still, and the rear end face 12b and the reflection surface 13m are kept at a predetermined distance while maintaining the parallelism.
D ₁ away.

Then, while keeping the relative positional relationship between the two chips 2 and 3 fixed, the two collets 4 and 5 are simultaneously moved downward to apply a predetermined load on the die bonding surface 1 on which the brazing material has been vapor-deposited in advance. The two chips 2 and 3 are pressed. In this state, the package is heated to melt the brazing material, followed by cooling and hardening.

As described above, when the LD chip 2 and the mirror chip 3 are simultaneously die-bonded without separately die-bonding, the time required for mounting the chip is 2 minutes and 10 seconds, compared with about 4 minutes conventionally. And about half the time.
Further, the temperature stress applied to the LD chip can be reduced by one die bonding. Also, both chips
Since the brazing material is hardened while applying a predetermined load to the two or three, the tip does not slightly displace, and the distance accuracy between the resonance surfaces of the external resonator formed by the rear end surface 2b and the reflection surface 3m is eliminated. Can be improved.

<Effects of the Invention> As is apparent from the above description, the present invention provides a semiconductor laser chip and a mirror chip capable of reflecting laser light, which are die-bonded on the same surface to form a laser light emitting surface of the semiconductor laser chip. And a reflecting surface of the mirror chip, wherein the semiconductor laser chip and the mirror chip are adsorbed by different collets, respectively. After the laser light emitting surface of the semiconductor laser chip and the reflecting surface of the mirror chip are brought into contact with each other in the space, the laser light emitting surface and the reflecting surface are separated from each other by a predetermined distance while maintaining the parallelism, and the relative position is maintained. Since the relationship is fixed and the die bond is made on the die bond surface at the same time, both chips are mounted on the package with one die bond It can reduce the time required for mounting and reduce the thermal stress on the LD chip,
In addition, the distance accuracy between the resonance surfaces can be improved.

[Brief description of the drawings]

1 (a) to 1 (d) are perspective views showing steps for mounting a chip of a wavelength-stable semiconductor laser according to the present invention.
FIGS. 1A to 1D are perspective views showing steps of mounting a chip of a conventional wavelength-stable semiconductor laser. 1 ... die bonding surface, 2 ... LD chip, 3 ... mirror chip, 3m ... reflection surface, 4 ... front collet, 5 ... rear collet.

Claims (1)

(57) [Claims] 1. A semiconductor laser chip and a mirror chip capable of reflecting laser light are die-bonded on the same surface, and external resonance occurs between a laser light emitting surface of the semiconductor laser chip and a reflection surface of the mirror chip. A method for manufacturing a wavelength-stable semiconductor laser, comprising a laser device, wherein the semiconductor laser chip and the mirror chip are attracted by different collets, and the laser light emitted from the semiconductor laser chip is emitted in a space other than the die bonding surface. After the surface and the reflecting surface of the mirror chip are brought into contact with each other, the laser light emitting surface and the reflecting surface are separated from each other by a predetermined distance while maintaining the parallelism, and the relative positional relationship is fixed, and the laser light emitting surface and the reflecting surface are fixed on the die bonding surface. A method for manufacturing a wavelength-stable semiconductor laser, wherein die bonding is performed at the same time.