JPH09191131A - Optical assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of securing an optical semiconductor element on a mount board to be mounted with an optical element in the direction of bonding, and prevent a metal alloy for bonding from flowing out to the light receiving surface or light emitting surface of the semiconductor element, by forming a step on the mount board in the position where the optical semiconductor element is to be secured. SOLUTION: A terrace 4 is formed on a silicon substrate 3 by etching, and a lower clad layer is formed. The lower clad layer is polished to the level of the terrace 4, and then a core layer is deposited. A pattern is formed, and recesses 5 of step structure, a waveguide 8 and a mating mark 7 are formed. An upper clad layer is formed, and then the terrace 4 is exposed. An optical semiconductor element 1 is fixed on the terrace 4 for alignment. Because of the presence of the recesses 5 for joining, a metal alloy film 6 for bonding stays within the recesses 5, and is prevented from flowing out to the end faces of semiconductor elements to be mounted. The semiconductor elements 2 are secured in an element mounting sections, and are connected with each other using a gold wire.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an optical subscriber system,
The present invention relates to a low-cost optical module and optical assembly applied to an optical interconnect system and the like.

[0002]

2. Description of the Related Art The conventional technology is Vol.
0 No. 5 (1995) reported by Ito et al.
An optical semiconductor module is a basic device that constitutes an optical communication system. These are a laser diode (LD) which is a light emitting element, a photodiode which is a light receiving element and an optical fiber, or an optical waveguide, and these are optically coupled. It is composed of a lens and a substrate for fixing and mounting these. Among these, when fixing the optical semiconductor element and the mount substrate, an electrode pattern is formed on the mount substrate, and an electrode pattern made of a metal film is also formed and fixed on the back surface of the optical semiconductor element.

When the optical semiconductor element is optically coupled to the optical waveguide or the optical fiber with low loss, the alignment accuracy of 1 μm or less with respect to the optical axis is required. In the direction parallel to the mount substrate, a method of forming alignment marks on the mount substrate and the optical semiconductor element, transmitting near-infrared light, observing the alignment marks at the same time, and performing alignment, and the surface of the solder Methods such as self-alignment using tension have been proposed as low-cost mounting methods. In the direction perpendicular to the mount substrate, a method has been proposed in which standoffs are provided on the substrate side and notches are provided on the semiconductor element side and they are brought into contact with each other to perform alignment in the height direction.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to improve the fixing accuracy in the direction perpendicular to the mount substrate, that is, in the direction of joining the semiconductor device and the mount substrate, and to receive the semiconductor element of a metal alloy for fixing. / To propose an optical assembly structure that prevents outflow to the light emitting surface.

[0005]

In order to achieve the above object, a step structure is formed at a position where an optical semiconductor element is mounted on a mount substrate on which the optical semiconductor element is mounted. The optical semiconductor element is brought into direct contact with the upper step of the step structure, and the metal film for fixing is bonded only to the lower step of the step structure. Thus, by separately forming the step for determining the fixing position and the step for joining, it is possible to improve the fixing accuracy of the optical semiconductor element. Further, since there are steps, it is possible to prevent the metal alloy melted and spread in the steps from flowing out to the end surface of the optical semiconductor element.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) An embodiment of the present invention is shown in FIG. In the manufacturing method of this embodiment, first, the silicon substrate 3 is etched by etching.
The terrace 4 is formed on the substrate 4 and the lower clad layer is formed by the flame deposition method. Next, after polishing the deposited clad film to the height of the terrace, a core layer is deposited and a pattern is formed by dry etching to form a recess 5, a waveguide 8 and an alignment mark 7 having a step structure. After the upper clad layer is formed again by the flame deposition method, the Si terrace portion is exposed by dry etching. Due to the difference in etching rate between silicon and quartz, etching stops at the silicon surface with which the semiconductor element is in contact. On the other hand, the depth of the recess (2 μm to 8 μm)
Since the etching rate can be controlled to about 0.1 to 1 μm per minute, it can be controlled with good reproducibility by time management. Next, titanium, platinum, and
The electrode 10 made of gold is formed and patterned. The metal alloy film 6 (AuSn thin film) for fixing is formed on the optical semiconductor element electrode by vapor deposition with a thickness (3 μm to 9 μm) that is not larger than the volume of the lower step.

In the optical semiconductor element 1, the alignment marks 7 formed on the semiconductor element and the substrate are simultaneously observed by an infrared camera by the infrared light transmission method and aligned in the plane direction. The semiconductor element 1 is fixed to the step 4 for fixing the position. The position of the optical semiconductor element and the mount substrate in the direction perpendicular to the substrate is determined by the contact surface between the step fixing step 4 and the optical semiconductor element. Further, the metal alloy film 6 for fixing remains in the step 5 for joining,
Outflow to the end surface of the optical semiconductor element is prevented. Next, the semiconductor element 2 is fixed to the element mounting portion by the same method. Further, the respective semiconductor elements are connected by the gold wires 9 and electrically connected to complete the first embodiment.

(Second Embodiment) Next, another embodiment will be described with reference to FIG. In the manufacturing method of this embodiment, first, V is formed by anisotropic etching of silicon so that the side wall becomes a (111) plane.
The groove 11 is formed. Next, pattern formation is performed to form the recess 5 and the alignment mark 7 having a step structure. Depth of recess (2
(μm to 8 μm) has an etching rate of 0.1 to 1 per minute.
Since it can be controlled to about μm, it can be controlled with good reproducibility by time management. Next, the electrode 10 made of titanium, platinum and gold is formed by the electron beam evaporation method and patterned. Metal alloy film 6 (AuSn thin film) for fixing
Is formed on the electrodes of the optical semiconductor device by vapor deposition so as to have a thickness (3 μm to 9 μm) not larger than the volume of the lower step.

In the optical semiconductor element 1, the alignment marks 7 formed on the semiconductor element and the substrate are simultaneously observed by an infrared camera by the infrared light transmission method and aligned in the plane direction, and then heated while applying a load to light. The semiconductor element is fixed to the step fixing step 4. The position of the optical semiconductor element 1 and the mount substrate 3 in the direction perpendicular to the substrate is determined by the contact surface between the position fixing step 4 and the optical semiconductor element 1. Further, since the metal alloy film 6 for fixing is present in the joining step 5 because of the joining step 5, outflow to the end face of the optical semiconductor element is prevented. Further, the optical semiconductor element 1 is connected with a gold wire 9 to establish electrical connection. Finally, the optical fiber 11 is fixed with an adhesive to complete the second embodiment.

[0010]

According to the present invention, the mounting position accuracy of the optical semiconductor element can be suppressed to 0.2 μm or less. In particular, since the height of the upper stage that determines the fixed position matches the core layer of the optical waveguide, the variation in the coupling loss between the optical semiconductor element and the optical waveguide or the optical fiber can be 0.2 dB or less as a result. Further, since the solder can be prevented from flowing out to the end face of the optical semiconductor element, the yield can be improved as a result, and a great effect can be exerted also in reducing the cost of the device.

[Brief description of the drawings]

FIG. 1 is a plan view and a sectional view of an optical assembly according to a first embodiment of the present invention.

FIG. 2 is a plan view and a sectional view of an optical assembly according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical semiconductor element, 2 ... Optical semiconductor element, 3 ... Mount substrate, 4 ... Position fixing step, 5 ... Joining step, 6 ... Metal alloy film, 7 ... Alignment mark for alignment, 8 ... Optical waveguide, 9
... gold wire, 10 ... electrode, 11 ... V groove, 12 ... optical fiber.

Claims (9)

[Claims] 1. An electrode pattern provided on the optical semiconductor element, comprising a mount substrate having an optical waveguide formed on a surface thereof, at least one optical semiconductor element and another semiconductor element mounted on the mount substrate. In an optical semiconductor device in which an electrode pattern provided on the mount substrate is fixed via a metal alloy, a step structure is formed at a position on the mount substrate where the optical semiconductor element is fixed. Light assembly. 2. A mount substrate having a V groove formed on its surface for fixing an optical fiber, an optical fiber fixed to the V groove, and at least one optical semiconductor element mounted on the mount substrate. An optical semiconductor device having another semiconductor element, wherein the electrode pattern provided on the optical semiconductor element and the electrode pattern provided on the mount substrate are fixed via a metal alloy, An optical assembly, wherein a step structure is formed at a position where an optical semiconductor element is fixed. 3. The optical assembly according to claim 1, wherein an index for alignment is formed on the upper surface of the step and the optical semiconductor element. 4. The semiconductor element has an optical waveguide structure,
4. The optical assembly according to claim 1, which has a light emitting function, and whose optical axis height is within. +-. 3 .mu.m and which matches the optical axis height of the optical waveguide on the mount substrate. 5. The semiconductor element has an optical waveguide structure and has a light-receiving function, and its optical axis height is within ± 3 μm and is equal to the optical axis height of the optical waveguide on the mount substrate. , 2, 3 or 4 optical assembly. 6. The optical assembly according to claim 1, wherein the optical waveguide connected to the light emitting element and the optical waveguide connected to the light receiving element are optically coupled. 7. A groove for mounting the mounted optical semiconductor element is covered with a lid.
The optical assembly described in. 8. The optical assembly according to claim 1, wherein the optical waveguide path is filled with resin in a groove in which the mounted optical semiconductor element is mounted. . 9. An optical transmission module using the optical assembly according to claim 1, 2, 3, 4, 5, 6, 7 or 8.