JP2003204051A - Photodetector and photodetecting device with built-in circuit and optical disc unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photodetector hard to oxidize an antireflection film, having stable signal output characteristics and suitable to receive a short wavelength light. <P>SOLUTION: The photodetector comprises a photodetectro section having a p-type diffused layer 101 and a p-type semiconductor layer 102 sequentially formed on a silicon substrate 100, and an n-type diffused layer 103 provided near a surface of the layer 102. The photodetector further comprises the antireflection film 108 having a first silicon oxide layer 105, a silicon nitride layer 105 and a second silicon oxide layer 107 sequentially provided in order from the side near the pohtodetector section on the pohtodetector section. Since the film 108 has the silicon oxide layer in an uppermost layer and is hard to be oxidized, its reflectivity to an incident light is stable for a long period so that the signal output characteristics are stable for a long period. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light receiving element, a circuit built-in light receiving device, and an optical disk device.

[0002]

2. Description of the Related Art Conventionally, an optical pickup unit used in an optical disc apparatus collects light emitted from a semiconductor laser on a disc by a lens, and the light intensity is modulated and reflected by a data writing portion of the disc. Is received by the light receiving element. The light receiving element detects a focus signal and a servo signal from a plurality of lights reflected on the disc, in addition to detecting the data written on the disc. Focus control is performed based on the detected focus signal, and servo control is performed based on the servo signal so that the disk is appropriately irradiated with laser light.

Conventionally, a light receiving element is provided with an antireflection film consisting of two layers of a silicon oxide layer and a silicon nitride layer, which are sequentially stacked from the light receiving portion side, on the surface on which the light receiving portion is provided ( See Japanese Patent Application Laid-Open No. 10-107312). Reflection of incident light is effectively suppressed by making the silicon oxide layer and the silicon nitride layer forming the antireflection film have appropriate layer thicknesses depending on the wavelength of incident light. For example, for incident light with a wavelength of 650 nm, the thickness of the silicon oxide layer having a refractive index of 1.46 is set to 37 n.
m, the thickness of the silicon nitride layer having a refractive index of 2.04 is 40 nm, and the reflectance of the antireflection film is 1%. Further, with respect to incident light having a wavelength of 405 nm, the thickness of the silicon oxide layer having a refractive index of 1.47 is set to 10 nm, and the thickness of the silicon nitride layer having a refractive index of 2.07 is set to 37 nm. The reflectance of the prevention film is 2
%I have to.

[0004]

However, in the conventional light-receiving element, when the surface of the antireflection film is exposed to the air, the silicon nitride layer on the surface of the antireflection film is gradually oxidized to cause reflection. The refractive index of the prevention film changes. Therefore, the reflectance of the antireflection film with respect to the incident light changes, the power of the light reaching the light receiving portion changes, and the value of the signal output from the light receiving element changes. As a result, there is a problem that the data cannot be accurately read from the disc.

The above problem becomes more serious as the wavelength of the light incident on the light receiving element becomes shorter. This is because short-wavelength light has a strong oxidizing action, and particularly light having a wavelength of 500 nm or less has a strong oxidizing action. Therefore, when such short-wavelength light enters, the surface layer of the antireflection film is rapidly oxidized. Because it will be. Further, in the antireflection film, the shorter the wavelength of the incident light, the larger the change in reflectance with the change in refractive index. For these reasons, in the above conventional light receiving element, when the short wavelength light is received, the surface layer of the antireflection film is rapidly oxidized, and this oxidation greatly changes the reflectance of the surface of the antireflection film. On the other hand, the power of the light reaching the light receiving unit changes greatly, and the signal output value also changes greatly. Therefore, there is a problem that the above-mentioned conventional light receiving element is not suitable for receiving light having a short wavelength.

Therefore, an object of the present invention is to provide a light-receiving element which has a stable signal output characteristic in which the antireflection film is hard to be oxidized and is suitable for receiving short-wavelength light.

[0007]

In order to achieve the above object, the light receiving element of the present invention has a light transmissive structure including a light receiving portion provided on a semiconductor layer and at least a plurality of layers laminated on the light receiving portion. In the light receiving element including a film, the uppermost layer of the plurality of layers of the light transmissive film is an oxide layer.

According to the above structure, the uppermost layer of the plurality of layers forming the light transmissive film is an oxide layer, and this oxide layer is relatively hard to be oxidized. Almost no oxidation when exposed. Therefore, the light transmissive film has almost no change in the refractive index, and thus has almost no change in the reflectance. As a result, in this light receiving element, the power of the light in the light receiving portion is almost unchanged with respect to the power of the light before entering the light receiving element over a long-time operation. As a result, this light receiving element can obtain a stable signal output value.
Further, even if the light received by the light receiving element is short-wavelength light, since the uppermost layer of the plurality of layers forming the light transmissive film is an oxide layer, the light transmissive film is less likely to be oxidized. Therefore, the reflectance of the light transmissive film hardly changes. As a result, a stable signal output characteristic can be obtained even if a short wavelength light is received, so that a light receiving element suitable for a short wavelength light can be obtained.

Further, since the light transmissive film is composed of a plurality of layers, the thickness of each of the plurality of layers is adjusted to
The reflectance of the entire light transmissive film can be effectively reduced, and a highly sensitive light receiving element can be obtained.

In the light receiving element of one embodiment, the light transmissive film is composed of a first silicon oxide layer, a first silicon nitride layer, and a second silicon oxide layer, which are sequentially stacked from the light receiving portion side.

According to the above embodiment, since the uppermost layer of the light transmissive film is a silicon oxide layer which is relatively hard to oxidize, the signal output of the light receiving element caused by the oxidation of the light transmissive film as in the prior art. A change in value is prevented, and a light receiving element with stable output characteristics can be obtained. Further, by adjusting the thicknesses of the first silicon oxide layer, the first silicon nitride layer, and the second silicon oxide layer, respectively, according to the wavelength of the incident light of the light receiving element, The reflectance for incident light of a wavelength can be effectively reduced.

In the light receiving element of one embodiment, the light transmissive film includes a first silicon oxide layer, a first silicon nitride layer, and a second silicon oxide layer, which are sequentially stacked from the light receiving portion side.
It is composed of a second silicon nitride layer and a third silicon oxide layer.

According to the above embodiment, since the uppermost layer of the light transmissive film is the silicon oxide layer which is relatively hard to oxidize, the change of the signal output value due to the oxidation of the light transmissive film is prevented. A light receiving element having stable output characteristics can be obtained. Further, depending on the wavelength of the incident light of the light receiving element, the thicknesses of the first silicon oxide layer, the first silicon nitride layer, the second silicon oxide layer, the second silicon nitride layer, and the third silicon oxide layer are By adjusting each, the reflectance of the entire light transmissive film with respect to the incident light of the above wavelength can be effectively reduced.

Further, the light transmissive film is composed of the first silicon oxide layer, the first silicon nitride layer, the second silicon oxide layer, the second silicon nitride layer, and the third silicon oxide layer. Even if a light-transmitting resin or the like is placed on the light-transmitting film, the light-transmitting film can obtain a low reflectance without being affected by the resin or the like.

In the light receiving element of one embodiment, the light transmissive film is composed of a first silicon oxide layer and a first titanium oxide layer, which are sequentially stacked from the light receiving portion side.

According to the above embodiment, the uppermost layer of the light transmissive film is a titanium oxide layer which is relatively hard to oxidize and has a relatively high refractive index, and therefore is caused by the oxidation of the light transmissive film. A change in the signal output value is effectively prevented by the two layers of the first silicon oxide layer and the first titanium oxide layer, and a light receiving element having stable output characteristics can be obtained.

Further, by adjusting the thicknesses of the first silicon oxide layer and the first titanium oxide layer respectively in accordance with the wavelength of the light received by the light receiving element, the reflectance is low in the two layers less. A light transmissive film can be efficiently obtained. Also,
Even if a light-transmissive resin or the like is arranged on the light-transmissive film, the light-transmissive film is not affected by the resin and a good reflectance can be obtained.

In the light receiving device with a built-in circuit of one embodiment, the light receiving element and a signal processing circuit for processing a signal from the light receiving portion of the light receiving element are formed on the semiconductor layer.

According to the above structure, the light receiving element and the signal processing circuit are monolithically formed, and a small-sized light receiving device having stable output characteristics can be obtained.

An optical disk device of the present invention comprises the above-mentioned light receiving element or the above-mentioned circuit built-in type light receiving device.

According to the above construction, since the light receiving element having a stable output characteristic is provided, an optical disk device suitable for reading and writing an optical disk using short wavelength light can be obtained.

Although the light receiving portion and the signal processing circuit are provided in the semiconductor layer in the present invention, the semiconductor layer may be a semiconductor substrate.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings.

(First Embodiment) FIG. 1 is a sectional view showing a light receiving element of a first embodiment of the present invention. In the present embodiment, the contact, the metal wiring, the interlayer insulating film and the like formed after the contact process will be omitted in the description.

This light receiving element has an impurity concentration of about 1E18 cm ⁻³ and a thickness of 1 μm on a silicon substrate 100.
The P-type diffusion layer 101 is provided.
The P-type semiconductor layer 102 having an impurity concentration of about 1E13 to 1E16 cm ⁻³ and a thickness of about 10 μm to 20 μm is provided on the top. In the vicinity of the surface of the P-type semiconductor layer 102, the impurity concentration in the vicinity of the surface is 1E17 cm ^{−3 to} 1E20 cm.
^-3 of the N-type diffusion layer 103 is provided.
The PN junction formed by the type diffusion layer 103 and the P-type semiconductor layer 102 constitutes a light receiving section. In addition, this N
The impurities forming the type diffusion layer 103 may be V-valent elements, and may be other elements such as arsenic, phosphorus and antimony.

P-type diffusion layers 104 for making contact with the P-type diffusion layer 101 are formed near the left and right ends of the P-type semiconductor layer 102 in FIG. 1 from the surface of the P-type semiconductor layer 102. Is formed to reach. The impurities forming the P-type diffusion layers 101 and 104 may be other elements such as boron and indium as long as they are trivalent elements.

An antireflection film 108 as a light transmissive film formed by a normal silicon process is provided on the P-type semiconductor layer 102 and on the light receiving portion. The antireflection film 108 is composed of a plurality of layers, and the first silicon oxide layer 105 and the silicon nitride layer 1 are sequentially arranged from the side closer to the light receiving portion.
06, and the second silicon oxide layer 107. The silicon oxide layer forming the antireflection film 108 has a refractive index of 1.47, and the silicon nitride layer has a refractive index of 2.07. The first silicon oxide layer 105 has a thickness of 10 nm, the silicon nitride layer 106 has a thickness of 37 nm, and the second silicon oxide layer 107 has a thickness of 138 nm. As a result, the reflectance of the entire antireflection film is 2% with respect to the incident light having a wavelength of 405 nm.

Since the uppermost layer of the antireflection film 108 of the light receiving element is the second silicon oxide layer 107, the surface of the antireflection film 108 is not easily oxidized even if the antireflection film 108 is operated in the air. Here, the light having the wavelength of 405 nm effectively prevents the anti-reflection film 108 from being oxidized by the second silicon oxide layer 107, although it has a strong oxidizing action. Therefore, as in the past,
Oxidation progresses from the surface exposed to air, the refractive index of the antireflection film changes, the reflectance changes, and the power of the light reaching the light receiving part with respect to the power of the incident light changes, and the output characteristics change. Never. As a result, this light receiving element has stable output characteristics even if it receives short wavelength light for a long time, and can accurately output a signal according to the incident light for a long time.

In the above embodiment, the antireflection film 1 is used.
Even when the refractive index of each of the plurality of layers constituting 08 and the incident light wavelength are other than those described above, the reflectance of each layer is adjusted to about 2% by adjusting the thickness of each layer to increase the sensitivity of the light receiving element. Can be effectively improved.

Further, in the above embodiment, the layer forming the antireflection film 108 may have other functions such as being used as an interlayer insulating film, which can reduce the number of manufacturing steps of the light receiving element. You can

In the above embodiment, the light receiving section may have another structure.

Further, although the number of the light receiving portions is one in the above embodiment, a plurality of light receiving portions may be provided.

In the above embodiment, the antireflection film 10 is formed on the P-type semiconductor layer 102 and on the light receiving portion.
8 is provided, an antireflection film may be provided on the entire surface of the P-type semiconductor layer 102.

In the light-receiving element of the above embodiment, the N-type and P-type components of the light-receiving element may be reversed.

(Second Embodiment) FIG. 2 is a diagram showing a light receiving element of a second embodiment of the present invention. In the present embodiment, the contact, the metal wiring, the interlayer insulating film and the like formed after the contact process will be omitted in the description.

This light receiving element has an impurity concentration of about 1E18 cm ⁻³ and a thickness of 1 μm on a silicon substrate 200.
The P-type diffusion layer 201 is provided.
The P-type semiconductor layer 202 having an impurity concentration of about 1E13 to 1E16 cm ⁻³ and a thickness of about 10 μm to 20 μm is provided on the top. In the vicinity of the surface of the P-type semiconductor layer 202, N having an impurity concentration near the surface of about 1E17 to 1E20 cm ⁻³
The type diffusion layer 203 is provided, and the PN junction formed by the N type diffusion layer 203 and the P type semiconductor layer 202 constitutes a light receiving portion. The impurities forming the N-type diffusion layer 203 may be V-valent elements, and may be other elements such as arsenic, phosphorus and antimony.

In the vicinity of the left and right ends of the P-type semiconductor layer 202 in FIG. 2, P-type diffusion layers 204 for making contact with the P-type diffusion layer 201 are formed from the surface of the P-type semiconductor layer 202 to the P-type diffusion layer 201. Is formed to reach. The impurities forming the P-type diffusion layers 201 and 204 may be other elements such as boron and indium as long as they are trivalent elements.

An antireflection film 210 as a light-transmitting film formed by a normal silicon process is provided on the P-type semiconductor layer 202 and on the light receiving portion. The antireflection film 210 is composed of a plurality of layers, and in order from the side closer to the light receiving portion, the first silicon oxide layer 205, the first silicon nitride layer 206, the second silicon oxide layer 207, the second silicon nitride layer 208, and the third layer. It is composed of five layers of a silicon oxide layer 209. The silicon oxide layer constituting this antireflection film has a refractive index of 1.47, and the silicon nitride layer has a refractive index of 2.07. Then, the first silicon oxide layer 205 is formed to have a thickness of 16 nm, the first silicon nitride layer 206 is formed to have a thickness of 33 nm, the second silicon oxide layer 207 is formed to have a thickness of 69 nm, and the second silicon oxide layer 207 is formed to have a thickness of 69 nm. The thickness of the silicon nitride layer 208 is 49 nm, and the thickness of the third silicon oxide layer 209 is 139 nm. As a result, the reflectance of the entire antireflection film is set to 1% with respect to incident light having a wavelength of 405 nm.

The light receiving element having the above-mentioned structure is provided with the antireflection film 210.
Since the uppermost layer of the above is the third silicon oxide layer 209, the antireflection film 210 is hardly oxidized even when it is operated in the state of being exposed to air. Therefore, as in the conventional case, the antireflection film is oxidized and the refractive index is changed, and the reflectance is changed,
A change in the signal output value of the light receiving element with respect to the power of the incident light is effectively prevented. Further, the antireflection film 2
By adjusting the thickness of the 5 layers that make up 10
The reflectance of the entire antireflection film for incident light of 5 nm is 1%
Therefore, a light receiving element with good sensitivity can be obtained. Therefore, this light receiving element can maintain good characteristics for a long period of time even if it receives light of a short wavelength, which has a relatively strong oxidizing effect.

Here, in the light receiving element of the first embodiment, the antireflection film 108 is composed of three layers, but in this case, when the surface of the light receiving element is coated with a transparent resin, light having a wavelength of 405 nm is obtained. On the other hand, the reflectance cannot be reduced below 10%. On the other hand, in the light receiving element of the second embodiment, since the antireflection film 210 is composed of five layers, even when this light receiving element is coated with the transparent resin, as in the case where it is not coated with the transparent resin,
The reflectance of the antireflection film 210 can be set to 1%.
As a result, the light receiving element of the present embodiment has the same signal output value with respect to the incident light when resin-sealed and when not resin-sealed. There is no need to make different types depending on the presence or absence. Therefore, this light receiving element can be highly versatile and inexpensive.

The layer constituting the antireflection film 210 may also have other functions such as an interlayer insulating function, and in this case, the number of manufacturing steps of the light receiving element can be reduced. Here, when the transparent resin is coated, the uppermost third silicon oxide layer 20 of the antireflection film 210 is used.
The thickness of 9 does not affect the reflectance of the antireflection film 210. Therefore, in this case, the silicon oxide layer 209
Can have a thickness that functions as an interlayer insulating film.

In the above embodiment, the antireflection film 2 is used.
Even when the refractive index of each of the plurality of layers forming 10 and the incident light wavelength are other than the above, the reflectance can be set to about 1% by adjusting the thickness of each layer.

In the above-described embodiment, the N-type diffusion layer 203 is formed on the surface of the P-type semiconductor layer 202 to form the light receiving portion. However, the N-type semiconductor layer is laminated on the P-type semiconductor layer to form the light receiving portion. May be configured.

Although one light receiving unit is provided in the above embodiment, a plurality of light receiving units may be provided.

Further, in the above embodiment, the antireflection film 21 is formed on the P-type semiconductor layer 202 and on the light receiving portion.
Although 0 is provided, an antireflection film may be provided on the entire surface of the P-type semiconductor layer 202.

In the light-receiving element of the above embodiment, the N-type and P-type components of the light-receiving element may be reversed.

(Third Embodiment) FIG. 3 is a diagram showing a light receiving element of a third embodiment of the present invention. In the present embodiment, the contact, the metal wiring, the interlayer insulating film and the like formed after the contact process will be omitted in the description.

This light receiving element has an impurity concentration of about 1E18 cm ⁻³ and a thickness of 1 μm on a silicon substrate 300.
The P-type diffusion layer 301,
The P-type semiconductor layer 302 having an impurity concentration of about 1E13 to 1E16 cm ⁻³ and a thickness of about 10 μm to 20 μm is provided on the top. In the vicinity of the surface of the P-type semiconductor layer 302, N having an impurity concentration near the surface of about 1E17 to 1E20 cm ⁻³
A type diffusion layer 303 is provided, and the PN junction formed by the N type diffusion layer 303 and the P type semiconductor layer 302 constitutes a light receiving portion. The impurities forming the N-type diffusion layer 303 may be V-valent elements, and may be other elements such as arsenic, phosphorus and antimony.

At the left and right ends of the P-type semiconductor layer 302 in FIG. 3, P-type diffusion layers 304 for making contact with the P-type diffusion layer 301 are formed from the surface of the P-type semiconductor layer 302 to the P-type diffusion layer 301. Is formed to reach. The impurities forming the P-type diffusion layers 301 and 304 may be other elements such as boron and indium as long as they are trivalent elements.

An antireflection film 307 as a light transmissive film formed by a normal silicon process is provided on the P-type semiconductor layer 302 and on the light receiving portion. The antireflection film 307 is composed of two layers of a silicon oxide layer 305 and a titanium oxide layer 306 in order from the side closer to the light receiving portion. Silicon oxide layer 305 forming this antireflection film
Has a refractive index of 1.47 and a thickness of 19 nm. The titanium oxide layer 306 has a refractive index of 3.0 and a thickness of 16 nm. As a result, the reflectance of the entire antireflection film is set to 1% with respect to incident light having a wavelength of 405 nm.

The light-receiving element having the above structure is provided with the antireflection film 307.
The top layer of titanium oxide layer 3 is relatively stable against oxidation
Since it is 06, the antireflection film 307 is hardly oxidized even if it is operated in the state of being exposed to air. Therefore, it is possible to effectively prevent the change in the signal output value of the light receiving element with respect to the power of the incident light, which is caused by the oxidation of the antireflection film, the change in the refractive index and the change in the reflectance as in the conventional case.
Further, the thicknesses of the two layers constituting the antireflection film 307 are adjusted so that the reflectance of the entire antireflection film with respect to the incident light having a wavelength of 405 nm is set to 1%, so that a light receiving element having good sensitivity can be obtained. To be Therefore, this light receiving element can maintain good characteristics for a long period of time even if it receives light of a short wavelength, which has a relatively strong oxidizing effect.

Here, in the light receiving element of this embodiment, the side surface of the light receiving portion may be coated with a transparent resin. In this case, for the two layers constituting the antireflection film 307, the silicon oxide layer 305 is formed to have a thickness of 8 nm and the titanium oxide layer 306 is formed to have a thickness of 24 nm. Then, in the light receiving element coated with the transparent resin, the reflectance of the antireflection film 307 can be set to 4% with respect to the incident light having the wavelength of 405 nm. Therefore, in this light receiving element, the signal output value with respect to the incident light can be made substantially the same between the case where the resin is sealed and the case where the resin is not sealed, only by changing the layer thickness of the layer forming the antireflection film 307. As a result, it is not necessary to make the signal processing circuit of this light receiving element differently depending on the presence or absence of resin sealing.
This light receiving element can obtain high versatility at a relatively low cost.

Further, the light receiving element of this embodiment has substantially the same reflection as the antireflection film 108 formed of three layers of the first embodiment and the antireflection film 210 formed of five layers of the second embodiment. Since the prevention function is obtained by the two layers, the number of manufacturing steps of the light receiving element can be reduced.

The layer constituting the antireflection film 307 may also have other functions such as an interlayer insulating function, and in this case, the number of manufacturing steps of the light receiving element can be reduced.

In the above embodiment, the antireflection film 3 is used.
Even when the refractive index of each of the plurality of layers constituting 07 and the incident light wavelength are other than those described above, the reflectance can be made approximately the same as the above case by adjusting the thickness of each layer.

Further, in the above embodiment, the N-type diffusion layer 303 is formed on the surface portion of the P-type semiconductor layer 302 to form the light receiving portion. However, the N-type semiconductor layer is laminated on the P-type semiconductor layer to form the light receiving portion. May be configured.

Further, in the above embodiment, one light receiving section is provided, but a plurality of light receiving sections may be provided.

Further, in the above embodiment, the antireflection film 30 is formed on the P-type semiconductor layer 302 and on the light receiving portion.
7 is provided, an antireflection film may be provided on the entire surface of the P-type semiconductor layer 302.

In the light-receiving element of the above embodiment, the N-type and P-type components of the light-receiving element may be reversed.

(Fourth Embodiment) FIG. 4 is a diagram showing a light-receiving device with a built-in circuit according to a fourth embodiment of the present invention. In this light receiving device with a built-in circuit, a light receiving element D of the present invention and a bipolar transistor T for treating a signal from the light receiving element D are formed on the same semiconductor layer. In the present embodiment, the description will be omitted by omitting the multi-layered wiring and the interlayer insulating film formed after the metal wiring processing step.

This photodetector with a built-in circuit is provided on the silicon substrate 400 having a boron concentration of about 1E15 cm ⁻³ to reduce the parasitic resistance generated at the anode of the photodetector D and has a thickness of 1 to 2 μm. Boron concentration is 1E1
The first P-type diffusion layer 401 having a thickness of about 8 to 1E19 cm ⁻³ is provided. A film thickness of 15 to 1 is formed on the first P-type diffusion layer 401.
A first P-type semiconductor layer 402 having a thickness of 6 μm and a boron concentration of about 1E13 to 1E14 cm ⁻³ is formed.

On this first P-type semiconductor layer 402, an N-type diffusion layer 414 serving as a collector is formed in a part of the region where the bipolar transistor T is formed.

On the first P-type semiconductor layer 402,
The film thickness is 1-2 μm and the boron concentration is 1E13-1E14c.
A second P-type semiconductor layer 411 of about m-3 is formed. On the second P-type semiconductor layer 411, locos regions 403, 403 ... For forming element isolation are formed.

Near the surface of the second P-type semiconductor layer 411, the N-type semiconductor layer 404 having a phosphorus concentration of about 1E19 to 1E20 cm −3 and a junction depth of about 0.3 to 0.8 μm.
Are formed to form the light receiving portion of the light receiving element D. On this N-type semiconductor layer 404, the same antireflection film 405 as the antireflection film 108 of the first embodiment is arranged. That is, the antireflection film 405 is composed of the first silicon oxide layer, the silicon nitride layer, and the second silicon oxide layer in order from the side closer to the light receiving portion. In FIG. 4, the boundaries between the three layers forming the antireflection film 405 are omitted. When forming the antireflection film 405, one or more layers forming the antireflection film 405 are also laminated in the formation region of the bipolar transistor T to form an interlayer insulating film and a cover for protecting the element. May be formed.

Further, the boron concentration for connecting to the first P-type diffusion layer 401 and contacting the wiring is 1E18.
˜1E19 cm ⁻³ second P type diffusion layers 410, 41
0 is formed so as to penetrate the first P-type semiconductor layer 402 and the second P-type semiconductor layer 411 in the thickness direction.

In the region of the second P-type semiconductor layer 411 where the transistor T is provided, the phosphorus concentration is 2E15 to 2E.
A 16 cm ⁻³ N-type well structure 413 is formed. A part of the N-type well structure 413 has a phosphorus concentration of 1E19 to 2 serving as a collector contact of the transistor.
An N-type semiconductor layer 415 having an E19 cm ⁻³ is formed. Further, a part of the N-type well structure 413 has a boron concentration of 1E17 to 2E17 which is a base of the transistor.
A cm ⁻³ P-type semiconductor layer 416 is formed. Further, an N-type semiconductor layer 406 which functions as an emitter is formed on a part of the N-type well structure 413 by solid layer diffusion from polysilicon into which arsenic is implanted.

A cathode electrode (not shown) and an anode electrode 412 are formed on the light receiving element D, and a collector electrode 407, a base electrode 408, and an emitter electrode 409 are formed on the transistor T.

In the light receiving device with a built-in circuit having the above structure, the antireflection film 40 has a reflectance of about 2% for incident light of any wavelength.
5, the light is incident on the N-type semiconductor layer 404 as a light receiving portion, the power of light is converted into a signal output, and this signal output is processed by the bipolar transistor T. Since the uppermost layer of the antireflection film 405 is made of a silicon oxide layer and is hardly oxidized by incident light of short wavelength, the signal output value with respect to the optical power of the light receiving element is stable for a long period of time. Therefore, a small-sized light receiving device with a built-in circuit and excellent characteristics can be obtained.

Although the NPN type transistor is used in this embodiment, a PNP type transistor may be used, both the NPN type transistor and the PNP type transistor may be used, and a plurality of transistors may be provided.
In addition, the structure of the transistor is not limited to that described in this example, and another structure can be used.

Although the antireflection film 405 is the antireflection film of the first embodiment, any of the antireflection films of the second to third embodiments may be used.

Further, a plurality of light receiving portions may be provided.

In the above embodiment, the N-type and P-type components of the circuit built-in type light receiving device may be reversed.

(Fifth Embodiment) FIG. 5 is a diagram showing an optical pickup section provided in an optical disk device according to a fifth embodiment of the present invention. This optical pickup section includes the light receiving element of the present invention, and this light receiving element 506 includes five light receiving sections D1,
In addition to having D2, D3, D4 and D5, an antireflection film having the same structure as the antireflection film 108 of the first embodiment is provided on these five light receiving portions D1, D2, D3, D4 and D5.

This optical pickup section is equipped with a semiconductor laser 5
The light emitted from 00 is split into two tracking sub-beams and one signal reading main beam by the diffraction grating 501 for tracking beam generation. These lights are transmitted through the hologram element 502 as 0th order light,
After being converted into parallel light by the collimator lens 503, it is condensed on the disc surface 505 by the objective lens 554.
The condensed light is reflected by the disc surface 505 and the light intensity is modulated by pits formed on the disc surface, and the modulated reflected light is hologramed via the objective lens 504 and the collimator lens 503. It is incident on the element 502. This hologram element 5
At 02, the incident light is diffracted, and the diffracted first-order light is made incident on the five light receiving portions D1 to D5 of the light receiving element 506. Then, the signals output corresponding to the incident light on the five light receiving portions are added and subtracted to obtain the read signal and the tracking signal.

This optical pickup section is provided with the light receiving element 506 of the present invention. Since this light receiving element 506 has the same antireflection film as the antireflection film 108 of the first embodiment, the semiconductor laser 500 has a short wavelength. Even if it emits light
The light receiving element 506 can obtain a good sensitivity and a stable signal output value for a long period of time. Therefore, it is possible to obtain an optical pickup unit that can read and write a large-capacity optical disc at high speed by using short-wavelength light.

In this embodiment, instead of the light receiving element 506, the circuit built-in light receiving device of the fourth embodiment may be provided. In this case, the configuration of the circuit that processes the signal from the optical pickup section can be simplified.

Further, not only the optical system of this embodiment, but another optical system may be used.

The emitted light of the semiconductor laser is not limited to the short wavelength light and may be light of other wavelengths.

[0079]

As is apparent from the above, according to the light-receiving element of the present invention, the light-receiving portion provided on the semiconductor layer and the light-transmissive film including at least a plurality of layers laminated on the light-receiving portion. In the light receiving element including, the uppermost layer of the plurality of layers of the light transmissive film is an oxide layer, and thus the light transmissive film is further exposed to air to allow passage of short wavelengths. However, since it hardly oxidizes, the refractive index hardly changes and the reflectance hardly changes. Therefore, the ratio of the power of the light in the light-receiving portion to the power of the light incident on the light-transmitting film is kept uniform for a long period of time, so that a light-receiving element that operates stably even when receiving a short wavelength is obtained. .

According to the light receiving element of one embodiment, the light transmissive film includes a first silicon oxide layer, a first silicon nitride layer, and a second silicon oxide layer, which are sequentially stacked from the light receiving portion side. Therefore, oxidation of the light-transmitting film can be effectively prevented, and a light-receiving element having stable output characteristics can be obtained. Further, according to the wavelength of incident light of the light-receiving element, the first silicon oxide layer and the first silicon oxide layer By adjusting the thicknesses of the first silicon nitride layer and the second silicon oxide layer, the reflectance of the entire light transmissive film with respect to the incident light of the above wavelength can be effectively reduced.

According to the light receiving element of one embodiment, the light transmissive film includes the first silicon oxide layer, the first silicon nitride layer, the second silicon oxide layer, which are sequentially stacked from the light receiving portion side. Since it is composed of the second silicon nitride layer and the third silicon oxide layer, it is possible to effectively prevent the oxidation of the light transmissive film,
A light receiving element having stable output characteristics can be obtained, and the first silicon oxide layer can be formed according to the wavelength of incident light of the light receiving element.
By adjusting the thickness of each of the first silicon nitride layer, the second silicon oxide layer, the second silicon nitride layer, and the third silicon oxide layer, the reflectance of the entire light transmissive film with respect to the incident light of the above wavelength is adjusted. However, it can be effectively reduced. further,
Even if a light-transmissive resin or the like is disposed on the light-transmissive film, a low reflectance is obtained without being affected by the resin or the like.

According to the light receiving element of one embodiment, the light transmissive film is composed of the first silicon oxide layer and the first titanium oxide layer, which are sequentially stacked from the light receiving portion side. Of the first silicon oxide layer and the first titanium oxide layer depending on the wavelength of the light received by the light receiving element by effectively preventing the oxidization of the first silicon oxide layer. By adjusting the thicknesses respectively, a light-transmitting film having a low reflectance can be efficiently obtained with a small number of two layers. Furthermore, even if a light-transmissive resin or the like is arranged in the light-transmissive film, a good reflectance can be obtained with almost no influence of the resin.

According to the light receiving device with a built-in circuit of one embodiment, since the light receiving element and the signal processing circuit for processing the signal from the light receiving portion of the light receiving element are formed on the semiconductor layer, A small-sized light receiving device having stable output characteristics can be obtained.

According to the optical disk device of the present invention, since it is provided with the light receiving element or the circuit built-in light receiving device, an optical disk device suitable for reading and writing an optical disk using short wavelength light can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a light receiving element of a first embodiment of the present invention.

FIG. 2 is a diagram showing a light receiving element of a second embodiment of the present invention.

FIG. 3 is a diagram showing a light receiving element of a third embodiment of the present invention.

FIG. 4 is a diagram showing a light-receiving device with a built-in circuit according to a fourth embodiment of the present invention.

FIG. 5 is a diagram showing an optical pickup unit included in an optical disc device according to a fifth embodiment of the present invention.

[Explanation of symbols]

100 silicon substrate 101 P type diffusion layer 102 P-type semiconductor layer 103 N-type diffusion layer 104 P type diffusion layer 105 first silicon oxide layer 106 silicon nitride layer 107 second silicon oxide layer 108 Antireflection film

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tatsuya Morioka             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Isamu Okubo             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Hideo Wada             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company F-term (reference) 4M118 AA08 AB05 AB10 BA02 CA03                       CA34 CB13 FC09 FC18                 5F049 MA02 MB03 MB12 NA02 NA07                       NB08 RA08 SS03 SZ03 SZ04                       SZ13

Claims (6)

[Claims] 1. A light-receiving element comprising a light-receiving portion provided on a semiconductor layer, and a light-transmissive film including at least a plurality of layers laminated on the light-receiving portion, wherein a plurality of layers of the light-transmissive film are provided. The light receiving element characterized in that the uppermost layer is an oxide layer. 2. The light receiving element according to claim 1, wherein the light transmissive film is a first silicon oxide layer, a first silicon nitride layer, and a second silicon oxide layer, which are sequentially stacked from the light receiving portion side. A light receiving element comprising: 3. The light-receiving element according to claim 1, wherein the light-transmissive film is a first silicon oxide layer, a first silicon nitride layer, and a second silicon oxide layer that are sequentially stacked from the light-receiving portion side. And a second silicon nitride layer and a third silicon oxide layer. 4. The light receiving element according to claim 1, wherein the light transmissive film is composed of a first silicon oxide layer and a first titanium oxide layer, which are sequentially stacked from the light receiving portion side. Light receiving element. 5. The light-receiving element according to claim 1, and a signal processing circuit for processing a signal from a light-receiving portion of the light-receiving element, formed on the semiconductor layer. Built-in circuit type photo detector. 6. An optical disk device comprising the light receiving element according to claim 1 or the circuit built-in light receiving device according to claim 5.