JPS6373584A - Heat sink for array semiconductor laser - Google Patents

Abstract

PURPOSE:To conduct isolation in response to a layer element, and to enable high density packaging by forming the width of a cross section in size wider at the position of substrate depth than the position of a fusing surface in the sectional form of a trench along the direction of resonance of a semiconductor laser formed onto an silicon substrate surface to which the array semiconductor laser is fused. CONSTITUTION:An Si crystal layer 2 containing B can be shaped as a crystal layer through an epitaxial growth method. The layer 2 containing B is etched to a trench shape, using KOH as an etchant by employing a mask using a photo-resist. When the mixed liquid of ethylene diamine and pyrocatechol is heated at the boiling point of 116 deg.C and the Si substrate 1 is dipped into the mixed liquid, Si 1 is etched to a cellar shape that the layer 2 containing B is formed as eaves because the layer 2 has an extremely slow etching rate, and a trench 6 having narrow width in a fusing section with a laser and broad width in a deep section is shaped. When Sn 4 is evaporated, Sn does not adhere on the side walls of each trench 6, and only collects as Sn 5 on the bottoms of the trenches 6. Accordingly, electrodes 3a, 3b, 3c are not conducted, thus independently driving respective laser element.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat sink for mounting a semiconductor laser array used in an optical communication device, an optical information processing device, etc. [Prior Art] Arranged in an array When driving a large number of semiconductor lasers independently, a single optical disk head is used as a light source to introduce light as a signal carrier into an array of optical waveguide wiring formed on a substrate. It is widely used as a light source for multi-beam optical heads that have light beams. The spacing of the semiconductor laser array used in these is 50
The diameter is narrow from μm to 100 μm, and in order to avoid thermal interference between individual semiconductor elements and increase reliability,
It is desirable to heat-seal the growth layer side including the active layer to the heat sink from above the structure of the semiconductor laser, rather than the substrate side.

Normally, when using silicon (Si) as a heat sink for a single semiconductor laser, a gold electrode provided on the surface of the semiconductor laser having a crystal growth layer and a thick tin film provided on the Si surface are fused together. The tin on the Si surface is formed to have a thickness of several μm in order to absorb the difference in thermal expansion coefficient between the semiconductor laser and the Si.

[Problem that the invention seeks to solve]

An example of a semiconductor laser array that has been realized satisfying these conditions is a semiconductor laser array in which grooves are formed between the semiconductor laser elements by etching or processing with a cutter to electrically isolate the elements. A metal tin film compatible with the semiconductor laser array is formed by vapor deposition on a beryllium oxide substrate, which has insulating properties and high thermal conductivity, using a metal mask, etc., and is placed on this tin film and the surface of the semiconductor laser array. It is fused by alloying with a film such as gold. This conventional method of forming a tin film using a mask can only be applied to arrays with an array pitch of about 150 to 200 μm, and cannot be applied to thin arrays with an array pitch of about 50 μm. .

The usual manufacturing method for silicon crystal, which is often used as a heat sink for a single semiconductor laser, is to
A silicon wafer of approximately 0 μm is used as a substrate, and this is
A method is to make mesh-like cuts at intervals of m to 3 am with a width of several micrometers and a depth of about 100 to 200 μm, vapor deposit Sn on the entire surface, and then concentrate stress on the cuts to break into individual heat sink chips. It is being

To make a heat sink for a semiconductor laser array using high-resistance silicon, the electrical isolation between the arrays can be made by making the same (but shallower) cuts to cut each chip. , a method of vapor-depositing Sn after this is considered. However, in this case, the Sn
Since the thickness of the groove is large, a film is also formed on the side walls of the cut groove, making it impossible to achieve electrical isolation. Furthermore, as a simple method, it is possible to uniformly form Sn without making a cut for separation, and then pattern the Sn film by a combination of photolithography and chemical etching of Sn, or by laser trimming. In the chemical etching method of Sn, the surface of the Sn vapor deposited film changes due to the resist film formed as a mask, and in the laser trimming method, the re-deposition of Sn on both sides of the trimmed area causes the generation of paris, making it difficult to fuse with the semiconductor laser. I have to.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat sink for an array semiconductor laser which eliminates these problems, allows easy separation according to the laser elements, and enables high-density packaging.

[Means for solving problems]

In the structure of the present invention, in a heat sink for an array semiconductor laser in which a high-resistance silicon substrate is fused to the array semiconductor laser, the heat sink is placed at a position corresponding to approximately the middle of the light emitting point position of the array semiconductor laser in the direction of the resonator of the array semiconductor laser. grooves are formed on the surface of the silicon substrate along these grooves, and the cross-sectional width of these grooves is wider at a depth position of the substrate than at a position where the array semiconductor laser is fused.

[Effect]

By adopting the configuration of the present invention, the cross-sectional shape of the vortex along the resonance direction of the semiconductor laser formed on the surface of the silicon substrate to which the array semiconductor laser is fused can be adjusted so that the width of the cross-section is at the depth of the substrate from the position of the fusion surface. Because it can be formed wide, even if Sn, which is one of the soft metals used for fusing each laser element, is deposited thickly, it will not adhere to the side walls of the groove, and the electricity between the semiconductor laser elements after fusing will be reduced. It is possible to avoid physical conduct. Furthermore, Sn after Snn smoke deposition
Since there is no need to apply photoresist etc. on the film, S
Good fusion bonding can be achieved without causing any deterioration of the surface of the n-film.

〔Example〕

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a sectional view showing the configuration of an embodiment of the present invention.

In the figure, 1 is a high-resistance Si that serves as a heat sink, and 2 is this S.
Si crystal layer containing boron (B) provided on the surface of the il, 3
is a semiconductor laser array fused to a heat sink 1, and here an embedded laser is used in which each laser element can be driven independently just by separating the electrodes. 4 is a Sn vapor deposited film provided on the surface of the Si crystal layer 2 for fusion bonding, 5 is a sagging Sn film, and 6 is a groove for electrically separating individual laser elements.

In this embodiment, this cross-sectional shape is narrow at the joint part of the heat sink 1 with the semiconductor laser 3 and wide inside the substrate.
Sn is attached to the bottom of each of the six without adhering to the side wall of each of the six.
It just accumulates like 5. Therefore, there is no conduction between the electrodes 3a, 3b, and 3c of each laser element, and each laser element can be driven independently.

Such a full 6 can be formed as follows. That is, the Si crystal layer 2 containing B can be formed as a crystal layer by epitaxial growth or as a B-poured layer by ion implantation into the high-resistance Si substrate 1. This B
Layer 2 containing
Etching is carried out in a spiral using KOH as an etching liquid.

Furthermore, add 1 part of a mixture of ethylenediamine and pyrocatechol.
When the Si substrate 1 is heated to a boiling point of 16° C. and immersed in this mixture, etching occurs at a rate of about 50 μm per hour. At this time, since the etching speed of the Si layer 2 containing B is extremely slow, the Sil is etched into a water-containing shape surrounding the B-containing layer 2, and the fused portion with the laser is formed as shown in the figure. In the deep part, the width is narrow (but in the deep part, the width is wide).

〔Effect of the invention〕

As described above, according to the present invention, a heat sink for a semiconductor laser array suitable for high-density packaging can be obtained, since it is possible to easily form a heat sink corresponding to a laser element.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Si for heat sink, 2... Si crystallinity including B, 3... Semiconductor laser array, 4... Sn vapor deposition film, 5... Accumulated Sn, 6... Etching groove ,
3a. 3b, 3c...Laser element electrode, 3d...Common'-,/

Claims (1)

[Claims] In a heat sink for an array semiconductor laser in which a high-resistance silicon substrate is fused to an array semiconductor laser, the silicon substrate 1. A heat sink for an array semiconductor laser, characterized in that grooves are provided on each surface, and the cross-sectional width of these grooves is wider at a depth position of the substrate than at a position where the array semiconductor laser is fused.