JP2006210494A - Optical semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device, where a photodiode (PD) of high speed and high photosensitivity and a transistor of high speed and high breakdown voltage are loaded together, on the same semiconductor substrate. <P>SOLUTION: In OEIC where the transistor and a light receiving element are loaded together on the same semiconductor substrate, an n-type epitaxial layer 20 is selectively formed on a silicon substrate 1. Since film thickness of an epitaxial layer is realized which is optimum for high performance of a vertical pnp transistor 3 and the photodiode 4, a structure for showing improvement of characteristics of respective elements to the maximum is realized and the characteristic can be improved as OEIC. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical semiconductor device in which a light receiving element and a transistor are mixedly mounted on the same substrate.

  The light receiving element is an element that converts an optical signal into an electric signal, and is used in various fields. In particular, in the field of optical discs such as CD and DVD, it is important as a key device of an optical pickup device that reads and writes signals recorded on the optical disc. In recent years, due to the demand for higher performance and higher integration, it has been configured as a so-called optoelectronic integrated circuit (OEIC) in which photodiodes as light receiving elements and various electronic elements such as bipolar transistors, resistors and capacitors are mounted on the same substrate. Yes. In the OEIC, a light receiving element having high light receiving sensitivity, high speed, and low noise characteristics and a high speed, high performance bipolar transistor are required to be mounted together.

  A conventional first optical semiconductor device will be described below.

  FIG. 10 is a schematic sectional view of an optical semiconductor device having a conventional structure, a so-called OEIC. In the illustrated example, an OEIC in which a silicon substrate is used as a semiconductor substrate, a vertical PNP transistor (V-PNP transistor) as a bipolar transistor, and a pin photodiode as a light receiving element is illustrated on the same substrate.

  1 is a low-concentration p-type silicon substrate, 2 is an n-type epitaxial layer formed on the silicon substrate 1, 3 is a V-PNP transistor formed on the n-type epitaxial layer 2, and 4 is on the n-type epitaxial layer 2 The pin photodiode is formed.

  In the V-PNP transistor 3, 5 is a high-concentration p-type emitter layer, 6 is an n-type base layer formed under the emitter layer 5, 7 is a p-type collector layer formed under the base layer 8, 8 is a high-concentration n-type buried layer formed under the collector layer 7, 9 is an emitter electrode, 10 is a base electrode, and 11 is a collector electrode. Currents flowing through the emitter layer 5, the base layer 6, and the collector layer 7 are taken out from the emitter electrode 9, the base electrode 10, and the collector electrode 11, respectively.

  A high-concentration p-type isolation layer 12 electrically insulates and isolates elements such as the V-PNP transistor 3 and the photodiode 4.

  In the photodiode 4, 13 is a cathode layer made of the n-type epitaxial layer 2, 14 is a high-concentration n-type cathode contact layer formed on the cathode layer 13, and 15 is a cathode electrode formed on the cathode contact layer 14. It is.

  Reference numeral 16 denotes a high-concentration p-type anode contact layer also used as the separation layer 12, and 17 denotes an anode electrode formed on the anode contact layer 16. The anode region is a region of the low-concentration p-type silicon substrate 1 below the cathode electrode 15. From the anode electrode 17 through the anode contact layer 16 for holes and the cathode contact layer 14 for electrons. Via the cathode electrode 15 and taken out as current. 18 is a light receiving surface on the upper side of the cathode contact layer 14, and an antireflection film is often provided to reduce reflection at the interface of incident light.

The operation of the OEIC configured as described above will be described below.
Light enters from the light receiving surface 18 and is absorbed by the cathode layer 13 and the silicon substrate 1 serving as the anode, generating electron / hole pairs. At this time, when a reverse bias is applied to the photodiode 4, the depletion layer spreads on the silicon substrate 1 side having a low impurity concentration, and among the electron-hole pairs generated in the vicinity of the depletion layer, the electrons enter the cathode contact layer 14. The holes reach the anode contact layer 16 by diffusion and drift, and a photocurrent is generated. In response to this photocurrent, the electronic circuit formed by the V-PNP transistor 3, the resistance element, and the capacitance element is amplified and signal-processed and output to become an optical disc recording and reproduction signal.

  However, in this structure, in order to ensure the withstand voltage of the V-PNP transistor 3, the n-type epitaxial layer 2 normally requires a film thickness of 2.5 μm or more. On the other hand, the photocurrent in the photodiode 4 is broadly divided into a diffusion current component and a drift current component. Since the diffusion current is dominated by the diffusion of minority carriers to the end of the depletion layer, the drift current component is caused by the electric field in the depletion layer. In comparison, the response speed is slow, which causes the frequency characteristics of the photodiode 4 to deteriorate. Therefore, in order to increase the speed of the photodiode 4, it is necessary to completely deplete the vicinity of the PN junction, and it is advantageous that the thickness of the n-type epitaxial layer 2 is thin (usually 1 μm or less). Therefore, it is difficult to integrate the high-speed V-PNP transistor 3 and the high-speed photodiode 4 on the same substrate.

  As a method for solving this problem, a technique for selectively etching the epitaxial layer of the photodiode portion has been proposed.

  Hereinafter, an optical semiconductor device that selectively etches the epitaxial layer of the photodiode portion, which is disclosed in Patent Document 1, will be described with reference to FIG.

  Reference numeral 19 denotes an etching region formed by selectively etching the n-type epitaxial layer 2 of the photodiode 4.

In this structure, the thickness of the cathode layer 13 of the photodiode 4 can be easily controlled independently of the thickness of the n-type epitaxial layer 2 by changing the depth of the etching region 19, and the thickness can be reduced to 1 μm or less. It becomes possible. That is, a thick film of the n-type epitaxial layer 2 of the V-PNP transistor 3 and a thin film of the cathode 13 layer can be realized simultaneously, and it is advantageous that the thickness of the n-type epitaxial layer 2 is small. Usually, it is 1 μm or less. Therefore, the high-speed V-PNP transistor 3 and the high-speed photodiode 4 can be integrated on the same substrate.
JP 2003-37259 A

  However, since the etching region 19 is generally formed by wet etching or the like, the etching depth varies. As a result, since the thickness of the cathode layer 13 varies, there arises a problem that it is difficult to ensure stable light receiving element characteristics.

  In addition, a pattern in which a plurality of photodiodes 4 are adjacent to each other is often used. In this case, photocurrent characteristics (scan characteristics) when light is scanned in the lateral direction are important. However, the stepped portion of the etching region 19 is formed by wet etching and thus has an inclined surface. When light hits this portion, it is irregularly reflected and the light is not stably incident on the photodiode 4, and stable scanning is performed. There arises a problem that characteristics cannot be obtained.

  The present invention solves the above-mentioned problems of the prior art. A high-speed transistor and a high-speed light-receiving sensitivity / high-speed light-receiving element are formed on the same substrate, which can reduce variations in the thickness of the cathode layer and obtain stable scanning characteristics. An object is to provide an optical semiconductor device mounted thereon.

  An optical semiconductor device of the present invention includes a first conductive type semiconductor substrate, a second conductive type epitaxial layer selectively formed on the semiconductor substrate, and a region in which no epitaxial layer is formed on the semiconductor substrate. A diffusion layer of the second conductivity type formed on the substrate, a light receiving element including the diffusion layer of the semiconductor substrate, and a transistor formed on the semiconductor substrate and the epitaxial layer.

  Another optical semiconductor device of the present invention includes a semiconductor substrate of a first conductivity type, an epitaxial layer of a first conductivity type selectively formed on the semiconductor substrate, and an epitaxial layer on the semiconductor substrate. A diffusion layer of a second conductivity type formed in a non-existing region, a light receiving element including a diffusion layer on a semiconductor substrate, and a transistor formed on the semiconductor substrate and the epitaxial layer.

  In the above configuration, the light receiving element has a light receiving element electrode formed on the surface of the epitaxial layer, and a light receiving element well layer formed so as to connect the semiconductor substrate and the light receiving element electrode.

  In the above configuration, the light receiving element well layer is formed on the entire surface of the step portion between the semiconductor substrate and the epitaxial layer in the region of the light receiving element.

  Another optical semiconductor device according to the present invention includes a first conductivity type semiconductor substrate, a second conductivity type first epitaxial layer formed on the semiconductor substrate, and a first epitaxial layer selectively. The formed second epitaxial layer of the second conductivity type, the semiconductor substrate in the region where the second epitaxial layer is not formed, the light receiving element formed on the first epitaxial layer, the semiconductor substrate, the first And the transistor formed on the second epitaxial layer.

  According to another optical semiconductor device of the present invention, a first conductivity type semiconductor substrate, a first conductivity type first epitaxial layer formed on the semiconductor substrate, and a first epitaxial layer selectively. A second epitaxial layer of the second conductivity type formed, a diffusion layer of the second conductivity type formed in a region where the second epitaxial layer on the first epitaxial layer is not formed, and a semiconductor substrate A light receiving element including a diffusion layer of the upper first epitaxial layer and a transistor formed on the semiconductor substrate, the first epitaxial layer, and the second epitaxial layer are provided.

  Another optical semiconductor device according to the present invention includes a first conductivity type semiconductor substrate, a second conductivity type first epitaxial layer formed on the semiconductor substrate, and a first epitaxial layer selectively. A second epitaxial layer of the second conductivity type formed, a semiconductor substrate and a second epitaxial layer on the first epitaxial layer are formed in a region where the second epitaxial layer is not formed, and a PN junction is formed in the semiconductor substrate. And a light-receiving element including a diffusion layer of the first epitaxial layer on the semiconductor substrate, and a transistor formed on the semiconductor substrate and the first and second epitaxial layers. It is characterized by that.

  According to another optical semiconductor device of the present invention, a first conductivity type semiconductor substrate, a first conductivity type first epitaxial layer formed on the semiconductor substrate, and a first epitaxial layer selectively. A second epitaxial layer of the second conductivity type formed, a semiconductor substrate and a second epitaxial layer on the first epitaxial layer are formed in a region where the second epitaxial layer is not formed, and a PN junction is formed in the semiconductor substrate. Second conductive type diffusion layer, a light receiving element including the diffusion layer of the first epitaxial layer on the semiconductor substrate, and a transistor formed on the semiconductor substrate, the first epitaxial layer, and the second epitaxial layer It is equipped with.

  In the above configuration, the light receiving element has a light receiving element electrode formed on the surface of the second epitaxial layer, and a light receiving element well layer formed so as to connect the first epitaxial layer and the light receiving element electrode.

  In the above configuration, the light receiving element well layer is formed on the entire surface of the step portion of the first epitaxial layer and the second epitaxial layer in the region of the light receiving element.

  In the above configuration, the thickness of the first epitaxial layer is 1.0 μm or less, and the thickness of the second epitaxial layer is 1.0 μm or more.

  In the above configuration, the transistor is a vertical PNP transistor.

  According to the optical semiconductor device of the present invention, the high-speed transistor and the high-speed light-receiving element can be formed on the same substrate because the epitaxial layer in the transistor portion can be made thick and the light-receiving element portion can be made thin simultaneously. It can be integrated on top. In addition, since the steps in the light receiving element are formed substantially vertically, irregular reflection can be reduced compared to the case of a slope, and stable light scanning characteristics can be obtained.

  Further, when the cathode electrode is formed on the semiconductor surface, the pattern formation can be simplified and miniaturized as compared with the case where the pattern is formed on the stepped portion.

(Embodiment 1)
A first embodiment of the optical semiconductor device of the present invention will be described below with reference to FIG.

First, as shown in FIG. 1, reference numeral 1 denotes a low-concentration p-type silicon substrate, and 20 denotes a low-concentration n-type epitaxial layer selectively formed on the silicon substrate 1.
3 is a V-PNP transistor, 4 is a photodiode, 5 is an emitter layer, 6 is a base layer, 7 is a collector layer, 8 is an n-type buried layer, 9 is an emitter electrode, 10 is a base electrode, and 11 is a collector electrode. . 12 is a separation layer, 14 is a cathode contact layer, and 15 is a cathode electrode. Reference numeral 16 denotes an anode contact layer, 17 denotes an anode electrode, and 18 denotes a light receiving surface, which are the same as those in the conventional structure.

  An example of a method for manufacturing the optical semiconductor device of the present embodiment configured as described above will be described.

  First, after an oxide film is selectively formed on the silicon substrate 1, epitaxial growth is performed. At this time, the n-type epitaxial layer 20 is formed only on the silicon substrate 1 on which no oxide film is formed. After removing the oxide film, an n-type cathode contact layer 14 is selectively formed in a region of the silicon substrate 1 where the n-type epitaxial layer 20 is not formed by an ion implantation process or the like. Next, the V-PNP transistor 3 is formed on the n-type epitaxial layer 2.

  The operation of the optical semiconductor device of the present embodiment configured as described above will be described below.

  The basic operation is the same as that described with reference to FIGS. When light is incident from the light receiving surface 18, the light is absorbed by the cathode contact layer 14 and the silicon substrate 1 serving as an anode, generating electron / hole pairs, and electrons diffuse into the cathode contact layer 14 and holes diffuse into the anode contact layer 16. And are separated by drift, and a photocurrent is generated. For example, when the concentration of the p-type silicon substrate 1 is made an order of magnitude lower than that of the n-type cathode contact layer 14, the depletion layer is formed at the interface between the cathode contact layer 14 and the silicon substrate 1, that is, near the PN junction. It extends only to the substrate 1 side and hardly extends to the cathode contact layer 14 side. Here, by making the concentration of the silicon substrate 1 extremely low, the width of the depletion layer can be made 10 μm or more. Especially in the case of light having a wavelength shorter than 650 nm used in DVD, The incident light is almost absorbed. That is, since the diffusion current component is reduced and the drift current component is dominant in the photocurrent, the photodiode 4 can respond at high speed.

  On the other hand, in this embodiment, since the film thickness of the n-type epitaxial layer 20 can be determined independently of the photodiode 4, by increasing the film thickness of the n-type epitaxial layer 20 (for example, 2.5 μm or more), V -Since the depth (for example, 1.5 μm or more) of the active region of the PNP transistor 3 can be sufficiently secured, it is easy to realize high performance characteristics such as high breakdown voltage.

In other words, the high-speed photodiode 4 and the high-speed, high-performance V-PNP transistor 3 can be formed on the same substrate, and a structure that maximizes the characteristics of each element can be realized. As a result, the characteristics can be improved.
In addition, since the step portion of the photodiode 4 is formed almost vertically, the irregular reflection of incident light is reduced as compared with the case where the step portion is an inclined surface, so that stable light scanning characteristics can be obtained. .
(Embodiment 2)
The second embodiment of the optical semiconductor device of the present invention will be described below with reference to FIG.

  As shown in FIG. 2, 21 is a low-concentration p-type epitaxial layer formed on the silicon substrate 1, and 22 is a high-concentration layer formed on the n-type buried layer 8 so as to completely surround the periphery of the collector layer 7. This is an n-type transistor well layer having a concentration. The n-type transistor well layer 22 plays a role of electrically separating the collector layer 7 and the p-type epitaxial layer 21. Other configurations are the same as those of the first embodiment.

The optical semiconductor device of this embodiment has a configuration using the p-type epitaxial layer 21 instead of the n-type epitaxial layer 20 of the first embodiment, and can achieve the same effect. In this configuration, the collector layer 7 and the p-type epitaxial layer 21 can be shared, and the process can be simplified. In addition, a transistor structure different from that of the first embodiment is possible.
(Embodiment 3)
Hereinafter, a third embodiment of the optical semiconductor device of the present invention will be described with reference to FIG.

  As shown in FIG. 3, 28 is a high-concentration n-type cathode well layer formed by diffusing from the n-type epitaxial layer 20 to the semiconductor substrate 1, and is connected to the cathode contact layer 14. Reference numeral 29 denotes a cathode surface electrode formed on the n-type cathode well layer 28. Other configurations are the same as those of the first embodiment.

In the first to second embodiments, the cathode electrode 15 of the photodiode 4 is formed below the step. In this case, formation of the pattern requires a complicated process, and there is a problem that miniaturization is particularly difficult. In the present embodiment, the absorbed electrons move in the path of cathode layer 13 → cathode contact layer 14 → cathode well layer 28 → cathode surface electrode 29, so that it is not necessary to form a cathode electrode in the stepped portion. Since the cathode surface electrode 29 is formed on the first n-type epitaxial layer 20, the process can be simplified and the pattern can be miniaturized.
(Embodiment 4)
Hereinafter, a fourth embodiment of the optical semiconductor device of the present invention will be described with reference to FIG.

  As shown in FIG. 4, 30 is a high-concentration n-type cathode well layer formed over the entire step portion of the n-type epitaxial layer 20 in the photodiode 4, and is connected to the cathode contact layer 14. Other configurations are the same as those of the third embodiment.

  In the present embodiment, the resistance of the n-type cathode well layer 30 can be reduced as compared with the third embodiment, the series resistance of the light receiving element is reduced, and a high-speed response can be realized.

Further, the cathode contact layer 14 and the cathode well layer 30 can be formed in the same process, and it is not necessary to pattern the stepped portion, so that the process can be simplified and miniaturized.
(Embodiment 5)
Hereinafter, a fifth embodiment of the optical semiconductor device of the present invention will be described with reference to FIG.

  First, as shown in FIG. 5, reference numeral 23 denotes a low-concentration first n-type epitaxial layer formed on the silicon substrate 1, and reference numeral 24 denotes a second n-type epitaxial layer selectively formed on the first n-type epitaxial layer 23. This is an n-type epitaxial layer. Reference numeral 13 denotes a cathode layer formed in the photodiode 4.

  1 is a silicon substrate, 3 is a V-PNP transistor, 4 is a photodiode, 5 is an emitter layer, 6 is a base layer, 7 is a collector layer, 8 is an n-type buried layer, 9 is an emitter electrode, 10 is a base electrode, 11 Is a collector electrode. 12 is a separation layer, 14 is a cathode contact layer, and 15 is a cathode electrode. Reference numeral 16 denotes an anode contact layer, 17 denotes an anode electrode, and 18 denotes a light receiving surface, which are the same as those in the first embodiment.

  In this embodiment, the first n-type epitaxial layer 23 is formed between the silicon substrate 1 and the n-type epitaxial layer 24 of the first embodiment. The cathode region of the photodiode 4 is constituted by the cathode layer 13 and the cathode contact layer 14, and the PN junction is formed at the interface between the silicon substrate 1 and the cathode layer 13.

  Since the V-PNP transistor 3 is composed of the first n-type epitaxial layer 23 and the second n-type epitaxial layer 24, the respective parameters can be designed independently. Compared with the second embodiment, the degree of freedom in design is increased.

  Since the thickness of the second n-type epitaxial layer 24 can be determined independently of the photodiode 4, the same effect as in the first embodiment can be obtained.

Further, since the thickness of the cathode of the light receiving element is determined by the film thickness of the first n-type epitaxial layer 23, the film thickness can be controlled with higher accuracy compared with the conventional forming method, and thus stable. It is possible to realize the light receiving element characteristics.
(Embodiment 6)
The sixth embodiment of the optical semiconductor device of the present invention will be described below with reference to FIG.

  As shown in FIG. 6, 25 is a low-concentration first p-type epitaxial layer formed on the silicon substrate 1, and 24 is a second n selectively formed on the first p-type epitaxial layer 25. The type epitaxial layer 26 is a high-concentration second n-type buried layer formed on the n-type buried layer 8 so as to completely surround the collector layer 7. The second n-type buried layer 26 plays a role of electrically separating the collector layer 7 and the p-type epitaxial layer 25. Other configurations are the same as those of the third embodiment.

The optical semiconductor device of this embodiment has a configuration using a p-type epitaxial layer 25 instead of the second n-type epitaxial layer 23 of the fifth embodiment, and can achieve exactly the same effect.
(Embodiment 7)
Hereinafter, a seventh embodiment of the optical semiconductor device of the present invention will be described with reference to FIG.

  As shown in FIG. 7, reference numeral 27 denotes a high-concentration n-type cathode contact layer formed by diffusing from the first n-type epitaxial layer 23 to the silicon substrate 1.

  Other configurations are the same as those of the fifth embodiment.

In the present embodiment, if a material having a band gap larger than that of silicon is used for the first n-type epitaxial layer 23, the energy of incident light is smaller than the band gap of the first n-type epitaxial layer 23, that is, The n-type epitaxial layer 23 passes through the long wavelength light and is absorbed only by the silicon substrate 1. In the structure of the first to fourth embodiments, the light receiving surface 18 and the outermost surface where light is absorbed coincide with each other, so that the light receiving element characteristics are easily influenced by the light receiving surface 18, and the light receiving sensitivity. Problems such as a decrease in leakage and an increase in leakage current occur. In the structure of this embodiment, the outermost surface that absorbs light is the interface between the n-type epitaxial layer 23 and the silicon substrate 1 and can be separated from the light receiving surface, so that it is possible to suppress a decrease in light receiving sensitivity and an increase in leakage current. .
(Embodiment 8)
The eighth embodiment of the optical semiconductor device of the present invention will be described below with reference to FIG.

  As shown in FIG. 8, 28 is a high concentration n-type cathode well layer formed by diffusing from the second n-type epitaxial layer 24 to the first n-type epitaxial layer 23. Connect. Reference numeral 29 denotes a cathode surface electrode formed on the n-type cathode well layer 28. Other configurations are the same as those of the fifth embodiment.

In the first to seventh embodiments, the cathode electrode 15 of the photodiode 4 is formed below the step. In this case, formation of the pattern requires a complicated process, and there is a problem that miniaturization is particularly difficult. In the present embodiment, the absorbed electrons move in the path of cathode layer 13 → cathode contact layer 14 → cathode well layer 28 → cathode surface electrode 29, so that it is not necessary to form a cathode electrode in the stepped portion. Since the cathode surface electrode 29 is formed on the surface of the second n-type epitaxial layer 24, the process can be simplified and the pattern can be miniaturized.
(Embodiment 9)
The ninth embodiment of the optical semiconductor device of the present invention will be described below with reference to FIG.

  As shown in FIG. 9, reference numeral 30 denotes a high concentration n-type cathode well layer formed over the entire step portion of the second n-type epitaxial layer 24 in the photodiode 4, and is connected to the cathode contact layer 14. Other configurations are the same as those of the eighth embodiment.

  In the present embodiment, the resistance of the n-type cathode well layer 30 can be reduced as compared with the eighth embodiment, the series resistance of the light receiving element is reduced, and a high-speed response can be realized.

  Further, the cathode contact layer 14 and the cathode well layer 30 can be formed in the same process, and it is not necessary to pattern the stepped portion, so that the process can be simplified and miniaturized.

  In this embodiment, the silicon substrate is used. However, the silicon substrate is not necessarily limited to the silicon substrate, and may be a germanium substrate or a compound semiconductor widely used in a long wavelength region, for example.

  Furthermore, in the present invention, a pin photodiode is used as the light receiving element, but it goes without saying that the present invention can also be applied to a normal pn-type photodiode, avalanche photodiode, and phototransistor. Also, a V-PNP transistor was used as the transistor. Needless to say, the present invention can also be applied to NPN transistors and MOS transistors.

  In the present invention, the p-type is used as the semiconductor substrate. However, it is needless to say that the n-type is applicable. In the above embodiment, the first epitaxial layer can also be p-type or n-type.

  In the above embodiment, it is desirable that the thickness of the first epitaxial layer is 1.0 μm or less and the thickness of the second epitaxial layer is 1.0 μm or more.

  The optical semiconductor device of the present invention makes it possible to integrate a high-speed transistor and a high-speed light-receiving element on the same substrate, reduce irregular reflection, and obtain stable light scanning characteristics. It has an effect and is useful for so-called OEIC in which a light receiving element and a transistor are integrated on the same substrate.

1 is a cross-sectional view showing an optical semiconductor device according to a first embodiment of the present invention. It is sectional drawing which shows the optical semiconductor device which concerns on 2nd Embodiment. It is sectional drawing which shows the optical semiconductor device which concerns on 3rd Embodiment. It is sectional drawing which shows the optical semiconductor device which concerns on 4th Embodiment. It is sectional drawing which shows the optical semiconductor device which concerns on 5th Embodiment. It is sectional drawing which shows the optical semiconductor device which concerns on 6th Embodiment. It is sectional drawing which shows the optical semiconductor device which concerns on 7th Embodiment. It is sectional drawing which shows the optical semiconductor device which concerns on 8th Embodiment. It is sectional drawing which shows the optical semiconductor device which concerns on 9th Embodiment. It is sectional drawing which shows the optical semiconductor device which concerns on a 1st prior art. It is sectional drawing which shows the optical semiconductor device which concerns on a 2nd prior art.

Explanation of symbols

1 silicon substrate 2 n-type epitaxial layer 3 V-PNP transistor 4 photodiode 5 emitter layer 6 base layer 7 collector layer 8 n-type buried layer 9 emitter electrode 10 base electrode 11 collector electrode 12 separation layer 13 cathode layer 14 cathode contact layer 15 Cathode electrode 16 Anode contact layer 17 Anode electrode 18 Light-receiving surface 19 Etching region 20 n-type epitaxial layer 21 p-type epitaxial layer 22 n-type transistor well layer 23 first n-type epitaxial layer 24 second n-type epitaxial layer 25 p-type Epitaxial layer 26 Second n-type buried layer 27 Cathode contact layer 28 n-type cathode well layer 29 Cathode surface electrode 30 n-type cathode well layer

Claims (12)

  A first conductivity type semiconductor substrate; a second conductivity type epitaxial layer selectively formed on the semiconductor substrate; and a first conductivity type formed on a region of the semiconductor substrate where the epitaxial layer is not formed. An optical semiconductor device comprising: a diffusion layer of two conductivity types; a light receiving element including the diffusion layer of the semiconductor substrate; and a transistor formed on the semiconductor substrate and the epitaxial layer.   A first conductivity type semiconductor substrate; a first conductivity type epitaxial layer selectively formed on the semiconductor substrate; and a first conductivity type formed on a region of the semiconductor substrate where the epitaxial layer is not formed. An optical semiconductor device comprising: a diffusion layer of two conductivity types; a light receiving element including the diffusion layer on the semiconductor substrate; and a transistor formed on the semiconductor substrate and the epitaxial layer.   3. The light according to claim 1, wherein the light receiving element has a light receiving element electrode formed on a surface of the epitaxial layer, and a light receiving element well layer formed so as to connect the semiconductor substrate and the light receiving element electrode. Semiconductor device.   4. The optical semiconductor device according to claim 3, wherein the light receiving element well layer is formed on the entire surface of the step portion between the semiconductor substrate and the epitaxial layer in the region of the light receiving element.   A semiconductor substrate of a first conductivity type, a first epitaxial layer of a second conductivity type formed on the semiconductor substrate, and a second conductivity type selectively formed on the first epitaxial layer The second epitaxial layer, the semiconductor substrate in the region where the second epitaxial layer is not formed, the light receiving element formed on the first epitaxial layer, the semiconductor substrate, the first epitaxial layer And a transistor formed on the second epitaxial layer.   A first conductive type semiconductor substrate; a first conductive type first epitaxial layer formed on the semiconductor substrate; and a second conductive type selectively formed on the first epitaxial layer. The second epitaxial layer, the second conductive type diffusion layer formed in the region where the second epitaxial layer on the first epitaxial layer is not formed, and the first epitaxial layer on the semiconductor substrate. An optical semiconductor device comprising: a light receiving element including the diffusion layer of the epitaxial layer; and a transistor formed on the semiconductor substrate, the first epitaxial layer, and the second epitaxial layer.   A semiconductor substrate of a first conductivity type, a first epitaxial layer of a second conductivity type formed on the semiconductor substrate, and a second conductivity type selectively formed on the first epitaxial layer A second epitaxial layer formed in a region where the second epitaxial layer is not formed on the semiconductor substrate and the first epitaxial layer, and a PN junction is formed in the semiconductor substrate. A conductive type diffusion layer; a light receiving element including the diffusion layer of the first epitaxial layer on the semiconductor substrate; and a transistor formed on the semiconductor substrate and the first and second epitaxial layers. An optical semiconductor device characterized by the above.   A first conductive type semiconductor substrate; a first conductive type first epitaxial layer formed on the semiconductor substrate; and a second conductive type selectively formed on the first epitaxial layer. A second epitaxial layer formed in a region where the second epitaxial layer is not formed on the semiconductor substrate and the first epitaxial layer, and a PN junction is formed in the semiconductor substrate. A diffusion layer of the conductivity type, a light receiving element including the diffusion layer of the first epitaxial layer on the semiconductor substrate, and the semiconductor substrate, the first epitaxial layer, and the second epitaxial layer. An optical semiconductor device including a transistor.   The light receiving element includes a light receiving element electrode formed on a surface of a second epitaxial layer, and a light receiving element well layer formed so as to connect the first epitaxial layer and the light receiving element electrode. The optical semiconductor device according to claim 8.   The optical semiconductor device according to claim 9, wherein the light receiving element well layer is formed on the entire surface of the step portion of the first epitaxial layer and the second epitaxial layer in the region of the light receiving element.   9. The optical semiconductor device according to claim 5, wherein the film thickness of the first epitaxial layer is 1.0 μm or less, and the film thickness of the second epitaxial layer is 1.0 μm or more. The optical semiconductor device according to any one of claims 1 to 8, wherein the transistor is a vertical PNP transistor.

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