JPH08271765A - Oeic array provided with lens - Google Patents

Abstract

PURPOSE: To obtain a practical OEIC array whose manufacture is easy by providing only one cylindrical surface type lens on the back surface of an OEIC chip on which a flip-chip type photodetector and an electronic integrated circuit are formed, and making the photodetective part of each photodetector an ellipse or a rectangle. CONSTITUTION: The OEIC array 1 is provided with four photodiodes arrayed in one line on the lower surface of the array 1. The photodetective parts 11a to 11d are formed toward the inside of the chip, and receive light transmitted through inside the chip. The parts 11a to 11d are formed, so that their shapes are ellipse including a long diameter which is in parallel with the arrayed direction of the parts 11a to 11d. On the other hand, a lens 12 having a cylindrical surface which follows a cylindrical surface having an axis in parallel with the arrayed direction of the photodiodes is formed on the upper surface. The lens 12 has a shape by which focal points are linked on the respective parts 11a to 11d of the photodiodes. By such constitution, the OEIC array provided with the lens whose tolerance with respect to the incident light is very large can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an OEIC (Optical Electronic Integrated Circuit) array with a lens. More specifically, the present invention relates to an OEIC including a flip-chip type light receiving element that receives light from the back surface of an integrated circuit chip, and more particularly to a novel structure of an OEIC array integrally including a plurality of light receiving elements.

[0002]

2. Description of the Related Art In the field of application of various information devices, which are rapidly expanding in use in recent years, particularly in systems for handling images or video, parallel computers, etc., it is necessary to handle an enormous amount of data as compared with the conventional one. It has become to. Therefore, various technological developments are underway to construct a system of this kind by taking advantage of the characteristics of an optical fiber capable of non-induction and high-density signal transmission.

However, since most of signal processing is currently handled by electric signals, frequent electric / optical or optical / electrical conversion is indispensable in a system using the optical transmission technology. Therefore, there is provided an optical module in which an optical element that performs optical / electrical conversion or electrical / optical conversion and an optical fiber that is a transmission medium of an optical signal are integrated, and this is used as an interface between an electronic circuit and an optical fiber. It is common to Further, in many cases, a drive circuit, an amplifier circuit and the like, which are unavoidably attached to the optical element, are integrally provided in the optical module. By using such an optical module, steps such as optical axis alignment required when coupling an optical fiber and an optical element can be omitted at the device manufacturing site, and an optical system can be efficiently constructed. It will be possible.

However, in consideration of application to the new architecture such as the above-mentioned parallel processing computer,
The number of channels of the optical signal transmission line becomes very large. Therefore, for example, an optical element array in which a plurality of optical elements are integrally packaged, a multi-core fiber having a plurality of cores by one, and the like have been developed to try to cope with multi-channel.

[0005]

When a system is constructed using a multi-core optical fiber, an OEIC array in which a plurality of optical elements and electronic circuits corresponding to the number of cores of the optical fiber are integrated is used. It would be convenient if possible. That is, the OEIC is an integrated circuit in which an optical element, which is a light receiving element or a light emitting element, and an ordinary electronic element are integrally integrated, using a compound semiconductor such as HEMT or HBT as a material. Therefore, for example, the photodiode, which is a light receiving element, and the amplifier and the like coupled immediately after the photodiode can be manufactured as an integrated circuit. Therefore, even when the number of channels is increased, a plurality of optical elements and electronic circuit elements may be formed at the same time. However, a single O
Simply connecting a plurality of EICs causes various problems as described below. Therefore, an OEIC array that can be actually used cannot be realized without solving all of these problems.

That is, the electronic circuit integrated in the OEIC array inevitably generates heat during its operation. Therefore, especially an OE including a large number of electronic circuits in an array.
The IC array chip must efficiently dissipate heat. Therefore, it has been proposed to adopt a typical solution to the problem of heat dissipation in a semiconductor integrated circuit and flip the OEIC array chip into a flip chip. That is, in a normal OEIC, after one surface of a semiconductor wafer is processed to form an integrated circuit, the unprocessed surface is fixed and mounted on a substrate or the like. However, it is known that the semiconductor wafer itself can be used as a heat sink to form a module that can be efficiently cooled by mounting the surface on which the integrated circuit and the like are formed on the mounting surface side.

However, when the OEIC is flip-chiped by such a method, the light receiving portion of the light receiving element receives the incident light through the semiconductor wafer itself. Therefore, there is a problem that the distance between the emission end of the optical fiber or the like and the light receiving portion of the light receiving element becomes large, and the tolerance of the incident optical axis with respect to the light receiving portion becomes small. Further, although the light receiving element is a current source in terms of an electric circuit, it also has characteristics as a capacitive element, and therefore, if the area of the light receiving portion is increased to increase the tolerance, the operating speed will be reduced. Therefore, in order to deal with such a problem, Japanese Patent Laid-Open No. 63-35114 discloses a technique of processing the back surface of a semiconductor wafer to form a spherical lens, and enlarging the positioning tolerance of incident light by this lens. ing.

However, in a typical multi-core fiber, the distance between the cores is about 120 μm, and when the OEIC array corresponding to this is constructed, the light receiving portions of the photodiodes must also have a pitch of 120 μm. However, when it is attempted to form a spherical lens by the technique disclosed in Japanese Patent Laid-Open No. 63-35114, the diameter of the spherical lens that focuses on the light receiving portion is larger than the light receiving portion pitch, and the rear surface of the OEIC array. It is very difficult to form a plurality of spherical lenses corresponding to each light receiving section. Further, it is very difficult to align the characteristics of the formed spherical lenses, and a light receiving element having sufficient tolerance to incident light and having the same light receiving characteristics is integrated.
EIC arrays have not been realized.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a novel OEIC array which is easy to manufacture and practical.

[0010]

According to the present invention, a semiconductor chip, a plurality of light receiving elements formed on one surface of the semiconductor chip so that light receiving portions are arranged in a row, and a plurality of light receiving elements of the light receiving element are provided. A plurality of electronic integrated circuits connected to each other and an optical lens formed on the other surface of the semiconductor chip are provided, and light is incident on the light receiving unit through the lens and the semiconductor chip. OEI with lens configured in
In the C array, each of the light receiving parts has a rectangular or oval shape having a long side or a major axis parallel to the array direction of the light receiving parts, and the lens is parallel to the array direction of the light receiving parts. Provided is an OEIC array with a lens, which has a cylindrical surface shape having various axes and is one cylindrical surface lens formed over the entire width of the semiconductor chip.

[0011]

The lens-equipped OEIC array according to the present invention is provided with only one cylindrical surface type lens on the back surface of the flip-chip type light-receiving element and the OEIC chip on which the electronic integrated circuit is formed, and the light-receiving element receives light. Its main feature is that the part is oval or rectangular.

That is, in the OEIC array with lens according to the present invention, the light receiving portions of the plurality of light receiving elements are arranged in one row, and the long side or the long diameter of the rectangular or oval light receiving portion corresponds to this arrangement direction. It is formed to be parallel.
Further, on the back surface of the OEIC chip, a cylindrical lens having an axis parallel to the arrangement direction is formed.

According to the above-mentioned structure, in the arrangement direction of the light receiving elements, a large tolerance with respect to the incident optical axis can be obtained depending on the shape of the light receiving section. Further, in the direction perpendicular to the array direction of the light receiving elements, a large tolerance can be obtained due to the condensing effect of the lens. Since the shape of the light receiving portion may be expanded only in the array direction of the light receiving portions, the deterioration of the characteristics due to the increase in the area of the light receiving portions is slight.

Further, since the OEIC array of the present invention corresponds to a plurality of light receiving portions with only one cylindrical lens, the lenses can be formed by a single process. Therefore, the productivity is good, and desired characteristics can be obtained regardless of the arrangement interval of the light receiving portions. Further, the optical characteristics of the lens do not differ for each light receiving unit.

Hereinafter, the OEIC array with lens according to the present invention will be described more specifically with reference to the drawings. However, the following disclosure is merely an example of the present invention, and the technical scope of the present invention is not limited thereto. Not something to do.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a specific configuration example of an OEIC array with lenses according to the present invention.

As shown in FIG. 1, this OEIC array 1
Is provided with four photodiodes arranged in a line on the lower surface in the figure. Light receiving part 11a of this photodiode
.About.11d are formed toward the inside of the chip, and the respective light receiving portions 11a to 11d receive the light transmitted through the inside of the chip.
In addition, each of the light receiving portions 11a to 11d is formed to have an elliptical shape including a long diameter parallel to the arrangement direction of itself.

On the other hand, on the upper surface of the OEIC array 1,
A cylindrical lens 12 is formed following a cylindrical surface having an axis parallel to the arrangement direction of the photodiodes. The cylindrical lens 12 is shaped so as to focus on the light receiving portions 11a to 11d of the photodiode.

The function of the OEIC array configured as described above will be described below.

FIG. 2 is a diagram for explaining the tolerance of the light receiving portion of the OEIC array shown in FIG. 1 in the x direction with respect to the incident light. As described above, the O according to the present invention
In the EIC array, each of the light receiving portions 11a to 11d is formed in an elongated shape so as to have a long side or a long diameter parallel to the arrangement direction. Therefore, the tolerance W _x is obviously wider than that of the light receiving portions 10a to 10d of the conventional OEIC array shown in FIG. 2 (a).

FIG. 3 is a diagram for explaining the tolerance of the light receiving portion of the OEIC array shown in FIG. 1 in the y direction with respect to the incident light. As shown in Figure 3 (b), this OE
Since the incident light is focused by the lens 12 in the IC array, the tolerance W _{y of the} incident light on the light receiving portions 10a and 11a having a constant width is larger than that of the general flip-chip type light receiving element shown in FIG. 3 (a). It is getting bigger.

The oblong light receiving portion of the light receiving element can be formed as follows. That is, the light receiving surface of the photodiode is formed by epitaxially growing the nip layer and then removing an unnecessary portion by wet etching. Therefore, if a mask having a rectangular hole pattern is used at the time of this etching process, a photodiode having an oval light receiving portion can be manufactured in exactly the same process as in the normal photodiode manufacturing. In such a method, since the etching rate is increased at the corners of the rectangular hole pattern, the shape of the light receiving surface finally formed is an ellipse.

The cylindrical lens 12 can be formed as follows. That is, first, TEOS or the like, which is a material of an optical component, is applied to the back surface of the wafer, and then this is etched using a resist mask having a linear pattern. As a result, since a ridge having a substantially trapezoidal cross section is formed, if the resist mask is removed and then wet etching is performed again, the entire shape becomes gentle and a substantially cylindrical lens is formed.

In the present embodiment, four-channel OEIC is used.
Although an array has been described, it goes without saying that more channel arrays can be manufactured with the same structure.

[0025]

As described above in detail, the lens-equipped OEIC array according to the present invention has a unique structure.
While having the characteristic of the flip-chip type integrated circuit that the heat generated in the electronic circuit can be efficiently dissipated, the tolerance for incident light is sufficiently large.

Further, in the OEIC array with lens according to the present invention, since the incident light to all the light receiving portions is focused by only one lens, there is no variation in characteristics between the light receiving portions. In addition, it is easy to manufacture.

Further, in the lens-equipped OEIC array according to the present invention, since the light receiving portion of the light receiving element has an elongated shape, the deterioration of the characteristics due to the expansion of the light receiving portion is small, and high performance and high density optical signal processing is possible. enable.

[Brief description of drawings]

FIG. 1 is a diagram showing a specific configuration example of an OEIC array with lenses according to the present invention.

FIG. 2 is a diagram showing an effect exerted by a shape of a light receiving portion in the OEIC array with lens shown in FIG.

FIG. 3 is a diagram for explaining a function of a lens in the OEIC array with a lens according to the present invention.

[Explanation of symbols]

1 ... OEIC array, 2 ... Optical fiber, 10a-10d, 11a-11d ... Light receiving part, 12 ...
..Cylinder surface lenses

Claims (3)

[Claims] 1. A semiconductor chip, a plurality of light receiving elements formed so that light receiving portions are arranged in a row on one surface of the semiconductor chip, and a plurality of light receiving elements connected to each of the light receiving elements. And an optical lens formed on the other surface of the semiconductor chip, and an OEIC array with a lens configured such that light is incident on the light receiving portion via the lens and the semiconductor chip. And each of the light receiving portions has a rectangular or oval shape having a long side or a major axis parallel to the arrangement direction of the light receiving portions, and the lens has an axis parallel to the arrangement direction of the light receiving portions. An OEIC array with a lens, which has a cylindrical surface shape and has one cylindrical surface lens formed over the entire width of the semiconductor chip. 2. The lens-equipped OEIC array according to claim 1, wherein the light receiving portions are arranged at an interval equal to the core pitch of the multi-core optical fiber. 3. The lens-equipped OEIC array according to claim 1 or 2, wherein the semiconductor chip is made of a compound semiconductor.