JP3935467B2 - Manufacturing method of optical semiconductor module - Google Patents

Description

The present invention relates to a method of manufacturing an optical semiconductor module that realizes stable optical coupling with a relatively simple structure for short-distance optical transmission.

  With improvements in the performance of electronic devices such as bipolar transistors and field effect transistors, a dramatic increase in operating speed has been achieved in large scale integrated circuits (LSIs). However, even if the LSI internal operation is speeded up, the operation speed at the printed circuit board level for mounting the LSI is suppressed lower than the internal operation of the LSI, and the operation speed is further suppressed at the rack level where the printed circuit board is mounted. These are due to the increase in transmission loss, noise, and electromagnetic interference of the electrical wiring accompanying the increase in the operating frequency, and the necessity of keeping the operating frequency lower for longer wiring in order to ensure signal quality. For this reason, in the electrical wiring apparatus, the tendency that the mounting technology dominates the system operation speed rather than the LSI operation speed has been increasing in recent years.

In view of such problems of the electrical wiring device, several optical wiring devices for connecting LSIs with light have been proposed. Optical wiring has almost no frequency dependency such as loss in a frequency range from DC to 100 GHz or more, and there is no electromagnetic interference in the wiring path or ground potential fluctuation noise. Therefore, wiring of several tens of Gbps can be easily realized. In order to realize this type of inter-LSI optical interconnection, an optical semiconductor module having a simple structure as shown in, for example, Patent Document 1 is required. In addition, a large number of optical transmission lines are necessary as LSI wiring, and it is necessary that the LSI wiring can be manufactured at very low cost.
JP 2000-347072 A

  Many common optical semiconductor modules cannot be miniaturized much because they incorporate an imaging lens or the like, and have an optical fiber coupling portion as a connector structure. On the other hand, in the optical semiconductor module as shown in Patent Document 1, since the optical transmission line such as an optical fiber and the optical semiconductor element are directly coupled and integrated, it is relatively easy to downsize. The problems are included.

  First, in the optical semiconductor module of Patent Document 1, since an optical fiber and its holding member are integrally formed and a pattern electrode for mounting an optical semiconductor element is formed thereon, any electrode pattern drawing or pattern transfer is very narrow. This must be done at the end of the optical fiber holding member. At least this is an essential content when using an arrayed optical semiconductor element. For this purpose, it is necessary to perform patterning with accuracy of several μm on a minute region with an optical fiber of several meters to several tens of meters attached, which is actually difficult to produce. That is, it is practically impossible to mass-produce this, or it can only be done with a very low yield.

Next, in the optical semiconductor module of Patent Document 1, the end face of the optical fiber and the surface on which the optical semiconductor element is mounted are substantially on the same surface, and the optical fiber and the optical semiconductor element are optically coupled very closely. However, surface-emitting lasers, which can be said to be representative of high-speed light-emitting elements, are sensitive to so-called reflected return light that is reflected by the laser beam emitted by the laser, and the return light (near-end reflection) at the optical fiber coupling portion Countermeasures and countermeasures for reflected light (far end reflection) on the optical fiber exit surface are important. The method using an optical isolator is the most reliable for this, but the optical isolator is not only very expensive, but the space for incorporating it greatly increases the size of the module. In addition, the optical fiber end face can be provided with a non-reflective coating or obliquely processed, so that a considerable countermeasure against return light is possible. However, in the conventional example such as Patent Document 1, the optical fiber and the holding member are integrally formed. Therefore, since the pattern electrode for the optical semiconductor element is formed, it is necessary to form a pattern for the non-reflective coating. This is also difficult in terms of productivity. Further, the influence of the return light can be mitigated by appropriately taking the distance between the surface emitting laser and the optical fiber. In other words, if the distance between the surface emitting laser and the optical fiber is extremely far away, the optical coupling is simply weakened and the optical transmission itself becomes difficult.However, if the distance is set appropriately, the optical coupling is lowered but the reflected return light is also reduced. While optical transmission is possible, the influence of reflected return light can be considerably suppressed. However, in the optical semiconductor module disclosed in Patent Document 1, it is practically difficult to control the distance between the optical semiconductor element and the end of the optical fiber. In particular, when the distance is close to 100 μm, the spacer thickness control and the optical fiber etching back-up are performed. However, it tends to be very poor in reproducibility.

  Next, as the biggest problem, in the optical semiconductor module of Patent Document 1, the end face of the optical fiber is formed by polishing, and the cost of this portion occupies a very large weight. In general, optical fiber polishing is a process bottleneck that requires several hours of processing, from fiber mounting and fixing to rough polishing, intermediate polishing, and final polishing, even if many optical fibers are simultaneously polished with an automatic device. Moreover, the cost reduction is limited.

The present invention has been made in consideration of the above-mentioned problems of the prior art, and is composed of the minimum necessary members, can reduce the influence of reflected return light, etc., and does not use a high-cost process such as polishing. An object of the present invention is to provide a method for manufacturing an optical semiconductor module that can be produced.

In order to achieve the above object, a method for manufacturing an optical semiconductor module according to one aspect of the present invention is such that a transparent resin film is pressed against a surface on which a protruding electrode of a photoelectric ferrule is formed, and the tip of the protruding electrode is positioned on the transparent resin. A step of protruding from a film, a step of mounting an optical semiconductor element on the protruding electrode, a step of inserting an optical transmission path into a guide of the photoelectric ferrule and pressing the transparent resin film against the optical semiconductor element; And a step of injecting a transparent resin between the optical semiconductor element and the photoelectric ferrule from the periphery of the optical semiconductor element to solidify.

According to the method of manufacturing an optical semiconductor module of the present invention, the material cost can be suppressed to a minimum with a very simplified configuration, and a small and highly functional optical semiconductor module can be mass-produced by only a low cost process. It becomes. Therefore, high-speed wiring between LSI chips can be realized at low cost, and it is possible to contribute to the advancement of information communication equipment and the like.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention does not grind the optical transmission line such as an optical fiber fixed to the holding member, but uses the end face formed by cleaving the optical fiber or batch etching of the optical waveguide as it is and optical coupling with the optical semiconductor element. In addition, a transparent resin spacer is inserted into the optical path in order to control the distance between the optical semiconductor element and the end face of the optical transmission path.

  FIG. 1 is a schematic cross-sectional view showing an optical semiconductor module of the present invention. In FIG. 1, 1 is a photoelectric ferrule, 2 is a protruding electrode and electrical wiring, 3 is an optical semiconductor element, 4 is an optical fiber core wire, 5 is a protective coating (of the optical fiber), 6 is a transparent resin spacer, and 7 is a transparent underlayer. A fill resin 8 is a guide for penetrating an optical transmission line (such as an optical fiber or an optical waveguide film). In FIG. 1, the protruding electrode 2 includes a support that is a main body constituting the protrusion, and an electrode portion. This electrode part has a multilayer structure in which, for example, Au, Pt, Ti or the like is laminated. The protruding electrode 2 is not limited to such a configuration, and for example, both the support and the electrode portion may be configured with silver paste.

  Since only the cross-sectional view of FIG. 1 is difficult to grasp the entire image, FIG. 2 shows an overall perspective view of the embodiment of FIG. Here, an example is shown in which four optical fibers are coupled to a four-channel optical semiconductor element array. In FIG. 2, 2a is a common electrode (grounding or power supply) of the 4-channel array, 2b is a signal electrode of each optical semiconductor element, and a right-angle bent wiring is formed on the side surface adjacent to the surface on which the optical semiconductor element is mounted. . The electrodes are drawn out to the adjacent side surfaces for connection (wire bonding, flip chip bonding, etc.) to the driving IC of the optical semiconductor element.

  Next, the manufacturing method of the optical semiconductor module of Example 1 of this invention is demonstrated using FIG. 3 thru | or FIG.

  3 to 6 are process cross-sectional views illustrating the manufacturing process of the optical semiconductor module of FIG. For example, the optoelectric ferrule 1 is formed by molding an epoxy resin mixed with about 80% of a glass filler of about 30 μm by resin molding using a mold, forming an optical fiber guide hole, a protruding portion of a protruding electrode, and a metal mask and sputtering, etc. Pattern metallization is performed to form two protruding electrodes and electrical wiring. As a result, one photoelectric ferrule can be mass-produced at a very low cost while having a very high accuracy of 1 μm or less.

A transparent resin sheet (spacer) 6 made of acrylic resin, silicone resin, epoxy resin, or the like is attached to the photoelectric ferrule (FIG. 3), and a contact plate 9 such as a rubber plate is pressed to attach the tip of the protruding electrode 2 to the transparent resin sheet 6. Protrude from. An optical semiconductor element (surface emitting laser, photodiode, etc.) is mounted thereon by flip chip bonding (FIG. 4). Then, the optical fiber 4 is inserted into the guide hole, and the optical fiber is pushed in until the transparent resin spacer 6 contacts the optical semiconductor element 3 (FIG. 5). At this time, when the optical fiber 4 is inserted while the optoelectric ferrule 1 is fixed, the optical semiconductor element may be pushed and peeled off from the two electrode pad portions. In order to prevent this, instead of holding and fixing one photoelectric ferrule, a backing plate is provided behind the optical semiconductor element 3 so that the optical semiconductor element 3 and the transparent resin spacer 6 are sandwiched between the optical fiber and the backing plate. Good. However, since the optical semiconductor element is generally fragile, the recoil pressure of the optical fiber is monitored so that the large recoil pressure is not applied, and the push of the optical fiber is stopped at a position where the recoil pressure slightly increases. As a range in which the recoil pressure slightly increases, a range in which the pressure is not applied to the optical semiconductor element due to elastic deformation of the 6 transparent resin spacers may be set.

  The optical fiber of No. 4 can obtain an optical end face with relatively high surface accuracy only by cutting with a general optical fiber cutter. This is because the optical fiber is not cut by breakage cutting or cutting, but a slight scratching with diamond is performed and stress cleavage by side extrusion is used. In the optical semiconductor module of the present invention, such a cut surface is used as it is, thereby eliminating a costly process such as polishing.

Finally, transparent resin (liquid) 7 is injected from the side surface on which the optical semiconductor element 3 is mounted to form an underfill (FIG. 6). At this time, the injection of the transparent underfill resin can be performed from the rear portion of the eight guide holes, or may be performed from a resin injection opening (not shown) provided on the side surface of the photoelectric ferrule. As the transparent underfill resin 7, a transparent resin such as acrylic, silicone, or epoxy may be used, and it is efficient to use a type that is cured by heating or ultraviolet irradiation. Further, as much as possible, it is desirable that the refractive index after curing matches the refractive index of the transparent resin spacer 6 in order to prevent excessive scattering loss.

  The present invention is not limited to the above-described embodiments. For example, various resins such as polyimide resin and polycarbonate resin can be selected as the transparent resin, and the optical fiber can be selected from quartz or plastic, and an optical waveguide film is used instead of the optical fiber. A simple selection is also possible. In addition, the present invention can be variously modified and implemented without departing from the spirit of the present invention.

Sectional drawing which shows schematic structure of the optical semiconductor module which concerns on Example 1 of this invention. 1 is a perspective view showing a schematic configuration of an optical semiconductor module according to Embodiment 1 of the present invention. Process sectional drawing of the structure of this invention which concerns on Example 2 of this invention. Process sectional drawing of the structure of this invention which concerns on Example 2 of this invention. Process sectional drawing of the structure of this invention which concerns on Example 2 of this invention. Process sectional drawing of the structure of this invention which concerns on Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photoelectric ferrule 2 ... Projection electrode 3 ... Optical semiconductor element 4 ... Optical fiber core wire 5 ... Protective coating 6 ... Transparent resin spacer 7 ... Transparent resin underfill 8 ... Guide

Claims (2)

Pressing the transparent resin film against the surface on which the protruding electrode of the photoelectric ferrule is formed to protrude the tip of the protruding electrode from the transparent resin film ;
Attaching an optical semiconductor element to the protruding electrode;
Inserting an optical transmission path into the guide of the photoelectric ferrule and pressing the transparent resin film against the optical semiconductor element; and
Injecting and solidifying a transparent resin between the optical semiconductor element and the photoelectric ferrule from the periphery of the optical semiconductor element ;
An optical semiconductor module manufacturing method comprising: Step to protrude the tip of the projecting electrode from the transparent resin layer is characterized to be made against the transparent resin film using a rubber plate to the surface on which protruding electrodes are formed of the photoelectric ferrule The manufacturing method of the optical-semiconductor module of Claim 1 .

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