JP2002289908A - Optical semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical semiconductor device, which is hardly influenced by external noise and also improves the visibility of an electrode at assembly work. SOLUTION: This optical semiconductor device is equipped with a light- receiving element chip 2 which has a light-receiving region 4, where a photodiode(PD) 8 is formed and a chip-mounting region 5 at its main face 2a; a signal output circuit 12 which processes the output signal of PD 8, and a signal processing IC chip 3 which has its input terminal part 13a and its output terminal part 13b; and a connector terminal part 7 is formed in the chip- mounting region 5; and also at least the chip-mounting region 5 is covered with a light-absorbing film 11 with the connector terminal 7 being exposed; and the signal-processing IC chip 3 is mounted on the chip-mounting region 5, so that, even if the light-receiving element chip 2 is irradiated with light, the light reflected from the main face 2a will not enter a circuit-forming face 14; and noise occurrence in the signal processing chip 3 is suppressed. Moreover, since the light-absorbing film 11 is small in quantity of reflected light, visibility of the connector terminal part 7 is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical semiconductor device for converting incident light into an electric signal.

[0002]

2. Description of the Related Art Conventionally, in various fields for converting light into an electric signal including optical communication, a photodiode,
2. Description of the Related Art An optical semiconductor device including a signal processing IC chip provided with a circuit for processing a signal output from a photodiode is used.

In such an optical semiconductor device, a light receiving element chip on which a photodiode is formed is connected to a signal processing IC.
When the C chip is electrically connected with a wire, the wire easily functions as an antenna to pick up an electromagnetic wave, and noise is generated in an electric signal. Further, the operation of the signal processing IC chip itself is easily affected by light, and noise is generated in the electric signal.
These electromagnetic waves and light may be shielded by a shield. However, the installation of the shield causes an increase in the number of components and the number of steps, and greatly reduces the manufacturing efficiency. Furthermore, the end of the wire may come off each chip, resulting in poor connection,
The occurrence rate of defective products due to the short circuit caused by the wire touching the edge of each chip is high. Therefore, by mounting the signal processing IC chip on the light receiving element chip so that the protruding electrode terminals (bumps) are connected to each other, noise generation is suppressed, production efficiency is improved, and the occurrence rate of defective products is suppressed. An optical semiconductor device is disclosed in JP-A-2000-307133.
Published in the official gazette.

[0004]

In the optical semiconductor device according to the above prior art, the surface of the signal processing IC chip on which the signal processing circuit is formed (circuit forming surface) is provided for the purpose of further shielding external light and electromagnetic waves. A metal film is provided on the back surface.

However, since a large number of Al wirings for power supply and signal processing are formed on the light receiving element chip, the reflected light is incident on the circuit forming surface of the signal processing IC chip. , Also a signal processing IC
Noise due to light or electromagnetic waves is generated in the output signal of the chip.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and is an optical semiconductor which is hardly affected by noise from the outside and has improved visibility of an electrode portion during an assembling operation. It is intended to provide a device.

[0007]

An optical semiconductor device according to the present invention comprises a light receiving area in which a photodiode for photoelectrically converting external light is formed, and a chip mounting area formed adjacent to the light receiving area. , A signal processing circuit for processing an output signal of a photodiode, and a signal processing IC having an input terminal portion and an output terminal portion electrically connected to the signal processing circuit on a main surface. A chip is provided, and a connection terminal portion for connecting to the input terminal portion and the output terminal portion is formed in the chip mounting region, and at least the chip mounting region is covered with a light absorbing film with the connection terminal portion exposed. The signal processing IC chip is connected so that the input terminal portion and the output terminal portion are connected to the connection terminal portion in a state where the circuit forming surface on which the signal processing circuit is formed faces the light receiving element chip. Characterized in that mounted on the flop mounting region.

According to the optical semiconductor device of the present invention, even if the light receiving element chip is irradiated with light, at least the chip mounting area is covered with the light absorbing film, so that the metal wiring formed on the light receiving element chip is formed. The reflected light does not enter the circuit forming surface of the signal processing IC chip. Therefore, it is possible to suppress the generation of noise due to the influence of light on the output signal of the signal processing circuit.

Further, since the light absorbing film covers the chip mounting area in a state where the connection terminal portion is exposed, a difference occurs in the amount of reflected light between the chip mounting area and the connection terminal section. Thereby, the visibility of the connection terminal portion (electrode portion) at the time of assembling work is improved, and the alignment at the time of mounting the signal processing IC chip on the light receiving element chip becomes easy.

It is preferable that the circuit forming surface of the signal processing IC chip is covered with a light absorbing film in a state where the input terminal portion and the output terminal portion are exposed. In this case, even when light is incident on the circuit forming surface of the signal processing IC chip, generation of noise in the output signal of the signal processing IC chip is suppressed.

The light absorbing film is preferably a black resist obtained by curing a liquid photosensitive resin containing carbon particles coated with an insulating material. In this case, the light-absorbing film can effectively absorb light, has high positional accuracy, and is hardly peeled off.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the optical semiconductor device according to the present invention will be described below in detail with reference to the accompanying drawings. Note that the same components are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 is a plan view showing an optical semiconductor device 1 according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along the line II-II in FIG.

As shown in FIGS. 1 and 2, the optical semiconductor device 1 comprises:
It comprises a light receiving element chip 2 and a signal processing IC chip 3 mounted on the light receiving element chip 2. The light receiving element chip 2 is a substrate 6 made of an n-type semiconductor (for example, silicon).
An insulating film (not shown) such as SiO2 or SiN is formed on the basis of the above. Also, the light receiving element chip 2
Denotes a light receiving region 4 which is a p-type impurity diffusion layer region on the main surface 2a.
And a chip mounting area 5 adjacent to the light receiving area 4. Therefore, in the light receiving region 4, the p-type impurity diffusion layer and the n-type semiconductor of the substrate 6 are PN-joined to form the photodiode 8. That is, when light enters the light receiving region 4 from the outside, it is photoelectrically converted and output as an electric signal.

In the chip mounting area 5 on the main surface 2a of the light receiving element chip 2, a bump electrode 7 made of a metal such as Au or In is formed as a connection terminal. In addition, the bump electrode 7 is made of a resin mixed with a conductive filler and an ACF (An
What can be electrically connected, such as an isotroptic conductive film, may be used. This bump electrode 7 is connected to the light receiving area 4.
And power supply and signal output electrode pads 9 formed in regions other than the chip mounting region 5 and the photodiodes 8 in the light receiving region 4, and wiring formed of a metal such as aluminum or a conductive material such as polysilicon. 10 are electrically connected to each other. Further, in the main surface 2 a of the light receiving element chip 2, the chip mounting region 5 excluding the bump electrodes 7 is a light absorbing film 11 from above the wiring 10, which is a liquid photosensitive resin containing carbon particles coated with insulation. This light absorbing film 1 is covered with a hardened black resist.
Numeral 1 has a characteristic of absorbing light to be detected.

On the other hand, the signal processing IC chip 3 has a signal processing circuit 12 for performing processing such as amplification on the output signal of the photodiode 8, and is electrically connected to the signal processing circuit 12 to connect the light receiving element chip 2. An input / output terminal unit 13 connected to the terminal unit 7 is formed. The input / output terminal 1
Reference numeral 3 includes an input terminal 13a and an output terminal 13b. The circuit forming surface 14 on which the signal processing circuit 12 is formed is covered with a black resist 11 obtained by curing a liquid photosensitive resin containing carbon particles coated with an insulating material while exposing the input / output terminals 13. Have been done.

Next, the operation of the optical semiconductor device 1 will be briefly described with reference to FIGS.

When the optical semiconductor device 1 is irradiated with light from the outside, the light incident on the light receiving region 4 is photoelectrically converted by the photodiode 8 and detected as an electric signal. Also,
In the region (chip mounting region) 5 covered with the light absorbing film 11, the light except for the bump electrode 7 and the wiring 10 is entirely covered with the light absorbing film 11, so that the incident light is absorbed. On the other hand, in an area other than the light receiving area 4 and in an area other than the chip mounting area 5, incident light is reflected by a wiring or the like on the main surface 2a of the light receiving element chip 2. However, the light reflected from the area other than the chip mounting area 5 does not enter the signal processing circuit 12 of the signal processing IC chip 3 because the reflection direction is not directed to the circuit forming surface 14.

Therefore, when the optical semiconductor device 1 is irradiated with light, the light reflected on the main surface 2a of the light receiving element chip 2 becomes
The signal does not enter the signal processing circuit 12 of the signal processing IC chip 3, and it is possible to suppress the generation of noise due to the influence of light on the output signal of the signal processing circuit 12. Therefore, even without providing a shield or the like that causes a decrease in manufacturing efficiency,
The output signal from the photodiode 8 in the light receiving area 4 can be made less susceptible to external noise or noise.

Next, a method for manufacturing the optical semiconductor device 1 of the present invention will be described. As shown in FIGS. 5 and 6, first, the semiconductor wafer 30 is subjected to steps such as a photolithography step, a deposition step, and an etching step to form a large number of semiconductor elements 31, and at the same time, the semiconductor elements 31 of the semiconductor wafer 30 are formed. A mark 32 for positioning with a photomask is formed in a region that is not formed. Here, as the mark 32 for positioning with the photomask, the mark 32 for positioning between the photomask and the semiconductor element 31 used when pattern exposure of the element in the photolithography step of the manufacturing process of the optical semiconductor element 1 is used. Can be. In addition,
The semiconductor wafer 30 is provided with an orientation flat 33 which is a notch indicating a crystallographic reference direction of the semiconductor wafer 30 for detecting a direction in a photolithography process. The marks 32 are provided at two positions substantially parallel to the orientation flat 33.

Next, as shown in FIGS. 7 and 8, a masking tape 34 is applied to the area where the semiconductor element 31 is not formed and which includes the area of the mark 32 to cover the mark 32. 9 and 10, a photosensitive black resist 11 is applied to the entire surface of the semiconductor wafer 30. In applying the photosensitive black resist 11, the semiconductor wafer 30 is set in a spin coating device for resist coating, a liquid photosensitive black resist is dropped, and a predetermined film thickness is obtained by rotating at 1000 rpm. Apply to. In addition, the black resist 11
In addition to covering the front surface of the surface on which the semiconductor element 31 is formed, the masking tape 34 is also covered. As the masking tape 34, a polyester film coated with an acrylic resin as an adhesive was used. In addition, the masking tape 34 can withstand the temperature during pre-baking (about 80 ° C.).
The material which does not transfer the adhesive layer to the semiconductor wafer 30 may be appropriately selected.

Subsequently, the semiconductor wafer 30 coated with the photosensitive black resist 11 is subjected to a heat treatment at, for example, 80 ° C. for about 30 minutes to pre-bake the photosensitive black resist 11 and to obtain a dimension during subsequent exposure. The solvent of the photosensitive black resist 11 which causes a defect is evaporated. By this pre-baking, the semiconductor wafer 30 and the photosensitive black resist 11 are in a state of being in close contact to some extent.

Next, as shown in FIGS. 11 and 12,
Peeling off the masking tape 34 from the semiconductor wafer 30;
The mark 32 is exposed. As a result, even if the photosensitive black resist 11 has perfect light shielding properties, the mark 32 can be detected by light.

Subsequently, the mask aligner device
The semiconductor wafer 30 according to the detected position of the mark 32
And a photomask (not shown). Then, the photosensitive black resist 11 is exposed by removing the photomask, developed, rinsed, and post-cured (for example, 230
C., 15 minutes), and then exposed to light.
Then, the unnecessary portion 1 is removed, and the patterning is completed. Thus, as shown in FIG. 13 and FIG.
Is formed in a predetermined pattern (a pattern in which only the connection terminal portion 7 is exposed in the chip mounting area 5) on the surface of the substrate.

Next, the signal processing IC chip 3 in a single chip area as shown in FIG.
2 with the circuit forming surface 14 facing the light receiving element chip 2 so that the connection terminal portions 7 corresponding to the input / output terminal portions 13 constituted by the input and output terminal portions 13a and 13b are electrically connected. Chip mounting area 5 on light receiving element chip 2
To be mounted on. The signal processing IC chip 2 is bump-connected while viewing the electrode pads 9 arranged on the main surface 2a of the light receiving element chip 2 as positioning markers. At this time, since the connection terminals 7 of the chip mounting area 5 are exposed from the black resist 11, it is easy to visually confirm.

At this time, when the electrical connection is made by using a metal bump, an Au ball or an In ball is formed on the connection terminal portion 7 on the light receiving element chip 2 and then the signal processing IC is viewed while looking at the positioning marker. Chip 2 is connected to the bump. On the other hand, in the case of the ACF, the light receiving element chip 2
Alternatively, after the ACF is temporarily bonded to the signal processing IC chip 3, the light receiving element chip 2 and the signal processing IC chip 3 are aligned while watching the position marker, and the temporary bonding is performed and the pressure bonding and curing are performed.

In each single chip area, a signal processing IC chip 3
After mounting, dicing is performed to separate each chip. If there is a possibility that the bump electrodes 7 are connected to each other due to shavings or the like from the light receiving element chip 2 during dicing and a defect such as a short circuit may occur, the light receiving element chip 2 and the signal processing IC before dicing. By filling the gap with the chip 3 with an underfill resin, there is no possibility that the yield may be reduced due to a short circuit or the like.

Next, an optical semiconductor device 20 according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a plan view showing the optical semiconductor device 20 according to the second embodiment of the present invention, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG.

In the optical semiconductor device 20, a region other than the light receiving region 4, the bump electrodes 7, and the electrode pads 9 in the main surface 2 a of the light receiving element chip 2 is covered with the light absorbing film 11 including the wiring 10. This is different from the optical semiconductor device 1. Therefore, when light is applied to the optical semiconductor device 20 from the outside, the light applied to regions other than the light receiving region 4, the bump electrode 7, and the electrode pad 9 is absorbed by the light absorbing film 11 that absorbs light to be detected. Is not reflected. Therefore, the irradiation light is not reflected and enters the signal processing circuit 12 of the signal processing IC chip 3. Further, even when external light enters the circuit forming surface 14 of the signal processing circuit 12 from an unspecified direction, the circuit forming surface 14
The noise generated in the output signal of the signal processing circuit 12 can be suppressed by the light absorbing film 11 covering.

Therefore, the signal processing circuit 1 is affected by light.
2 can be prevented from generating noise. Thus, even without providing a shield or the like that causes a decrease in manufacturing efficiency, it is possible to make the output signal from the photodiode 8 in the light receiving area 4 less susceptible to external noise or noise caused by electromagnetic waves or the like. You.

Further, the present invention is not limited to the above-described embodiment, and various modifications are possible.

For example, the photodiode 8 formed in the light receiving region 4 is not limited to a single diode, but may be a plurality of diodes arranged in an array. The method of electrically connecting the connection terminal 7 and the input / output terminal 13 is as follows.
It is not limited to bump connection, such as directly connecting electrode pads or connecting via a conductive substance, as long as it can reliably transmit electric signals and the like. The bump electrode portion is a signal processing IC chip It may be formed on the third side. Further, as the light absorbing film 11, different light absorbing films may be selected on the light receiving element chip side and the signal processing chip side.

[0033]

As described above, according to the present invention, the light receiving area and the signal processing IC chip can be easily connected without using wires. In addition, since there is no wire, light does not enter the connection portion with the signal processing IC chip, and at least the chip mounting area other than the connection terminal portion is covered with a light absorbing film such as a black resist, It is possible to prevent reflected light from the main surface of the light receiving element chip, particularly from signal wiring or the like, from being incident on the circuit forming surface of the signal processing IC chip, thereby reducing noise.

[Brief description of the drawings]

FIG. 1 is an optical semiconductor device 1 according to a first embodiment of the present invention.
FIG.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is an optical semiconductor device 2 according to a second embodiment of the present invention.
FIG.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3;

FIG. 5 is a plan view showing a semiconductor wafer before coating in a manufacturing process.

FIG. 6 is a sectional view taken along the line VI-VI of FIG. 5;

FIG. 7 is a plan view showing a semiconductor wafer after tape application before coating in a manufacturing process.

8 is a sectional view taken along the line VIII-VIII in FIG.

FIG. 9 is a plan view showing a semiconductor wafer after coating in a manufacturing process.

FIG. 10 is a sectional view taken along line XX of FIG. 9;

FIG. 11 is a plan view showing the semiconductor wafer after tape peeling after coating in a manufacturing process.

FIG. 12 is a sectional view taken along the line XII-XII in FIG. 11;

FIG. 13 is a plan view showing a semiconductor wafer on which a predetermined pattern is formed by a manufacturing process.

FIG. 14 is a sectional view taken along the line XIV-XIV in FIG.

[Explanation of symbols]

1 ... optical semiconductor device, 2 ... light receiving element chip, 2a ...
Main surface, 3 ... Signal processing IC chip, 3a ... Main surface, 4 ...
... Light receiving area, 5... Chip mounting area, 7... Bump electrode (connection terminal), 8... Photodiode, 11... Black resist (light absorbing film), 12.
a ... input terminal portion, 13b ... output terminal portion, 13 ... input / output terminal portion, 14 ... circuit formation surface.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshimuro Fujii 1126 Nomachi, Hamamatsu-shi, Shizuoka Prefecture F-term in Hamamatsu Photonics Co., Ltd. DD02 FC05 FC15 FC18 GB01 GB03 HA03 HA07 HA12 HA21 HA31 5F049 MA02 MB03 NA04 NB01 RA06 SS03 SZ10 UA05

Claims (3)

[Claims] A light receiving element chip having a light receiving area in which a photodiode for photoelectrically converting external light is formed, and a chip mounting area formed adjacent to the light receiving area on a main surface; And a signal processing IC chip having a main surface having an input terminal portion and an output terminal portion electrically connected to the signal processing circuit. A connection terminal portion for connecting to the input terminal portion and the output terminal portion is formed, and at least the chip mounting area is covered with a light absorbing film in a state where the connection terminal portion is exposed, and the signal processing IC chip includes: The input terminal portion and the output terminal portion are connected to the connection terminal portion in a state where a circuit forming surface on which the signal processing circuit is formed faces the light receiving element chip. The optical semiconductor device is mounted on the chip mounting area as described above. 2. The signal processing IC chip according to claim 1, wherein the circuit forming surface is covered with a light absorbing film in a state where the input terminal portion and the output terminal portion are exposed. Optical semiconductor device. 3. The optical semiconductor device according to claim 1, wherein the light absorbing film is a black resist obtained by curing a liquid photosensitive resin containing carbon particles coated with insulation.