JP2933870B2 - Photodetector and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photodetector and a method of manufacturing the same, and more particularly, to a photodetector having a wavelength band of 40.
The present invention relates to a photodetector used for detecting light close to human relative luminosity of 0 nm to 800 nm and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in order to detect light, a photodetector is generally used in which an optical filter or a spectroscope of a wavelength band to be detected is arranged in front of a light receiving portion such as a silicon photodiode.

[0003] However, there is a drawback that the shape of the photodetector becomes large and the cost increases. In order to solve this, a photodetector (for example, Japanese Patent Application Laid-Open No. 63-65325, Japanese Patent Application Laid-Open No. 2-291182) has been proposed.

FIG. 10 shows a conventional example as disclosed in JP-A-2-29.
1 shows a configuration of a photodetector disclosed in Japanese Patent Publication No. 1182.
In FIG. 10, 41 is a sensor complex, 42 is an amplifier including an operational amplifier or the like, 43 is a resistor, 44 and 45 are wires,
46 is a P-type semiconductor substrate, 47 and 48 are N-type impurity regions,
49 is a P-type impurity region.

[0005] The photodetector shown in FIG. 10 has a sensor complex 41 and an amplifier 42 as main components. Sensor complex 41, the first and the light-receiving portion PD ₁ 'and the second light receiving portion PD _2' having a different light detection characteristics each other, 'and the second light receiving portion PD _2' first light receiving portion PD ₁ and Are connected in reverse parallel to each other. Note that the first light receiving portion PD ₁ ′ includes a P-type semiconductor substrate 46 and an N-type impurity region 47.
And a second light receiving portion P
D ₂ ′ is a photodiode including an N-type impurity region 48 and a P-type impurity region 49. Here, connecting in anti-parallel means connecting in parallel with the polarity of the photodiode as the light receiving unit reversed. The amplifier 42 is connected to the first
The difference between the output currents of the light receiving section PD ₁ ′ and the second light receiving section PD ₂ ′ is amplified.

In this photodetector, the first light receiving portion P
When light is applied to D ₁ ′ and the second light receiving unit PD ₂ ′,
A photocurrent corresponding to each photodetection characteristic is generated in each light receiving unit, and a difference between these photocurrents is transmitted through the wiring 44 to the amplifier 4.
2 is output. The amount of generated photoelectric flow is proportional to the amount of light in a wavelength band in which each light receiving unit has sensitivity.

[0007]

However, the conventional photodetector has the following problems.

In the above-described light detecting device, the first light receiving section PD
₁ ′ and the second light receiving section PD ₂ ′ are connected in anti-parallel by wires 44 and 45. However, when connected in anti-parallel, if a reverse bias voltage is applied to one of the light receiving units, an excessive forward current will flow to the other light receiving unit.
The reverse bias voltage cannot be applied. For this reason,
The amplifier 42 that amplifies the difference between the photocurrents is limited to a positive / negative dual power supply type amplifier having an input bias voltage of 0V.
Thus, there is a problem that the circuit scale of the photodetector increases.

In addition, since a reverse bias voltage cannot be applied, the depletion layer does not expand at the junction between the P-type impurity region and the N-type impurity region. It is necessary to increase the area of the light receiving section in order to improve the image quality.

Further, when a spot light or the like smaller than the area of each light receiving portion is irradiated, there is a problem that the light amount in the wavelength band to be detected cannot be detected.

In view of the above problems, the present invention provides a photodetector capable of using various amplifiers and having a small circuit scale, and a method of manufacturing the same. It is an object of the present invention to provide a manufacturing method thereof, and to provide a light detection device capable of detecting the light amount of a wavelength band to be detected even when a spot light or the like smaller than each light receiving area is irradiated, and a manufacturing method thereof. I do.

[0012]

Means for Solving the Problems In order to solve the above-mentioned problems, a solution taken by the invention of claim 1 is a photo-detecting device, comprising a second conductive type formed on a semiconductor substrate of a first conductive type. A first light receiving portion including a first impurity region of the first type and a second impurity region of the first conductivity type formed on the first impurity region; the semiconductor substrate of the first conductivity type; and the semiconductor substrate. A second light-receiving unit, comprising a third impurity region of the second conductivity type formed thereon and having a spectral sensitivity characteristic different from that of the first light-receiving unit and connected in series with the first light-receiving unit If, a amplifying means for amplifying by inputting a difference current of the first photoelectric current generated in the first and second light receiving portions from the connecting portion between the and the light receiving portion and the second light receiving portion, wherein Main surface of semiconductor substrate
A portion in which the first impurity region is formed, and a back surface
By applying a voltage between the first and second
And a reverse bias voltage is applied to the second light receiving section.
It is a thing.

According to the first aspect of the present invention, when the same light is applied to the first light receiving portion and the second light receiving portion, a photocurrent is generated according to the respective light detection characteristics. Since the difference current between the photocurrents is amplified by the amplifying means, the output current of the amplifying means is proportional to the amount of light in the wavelength band to be detected. Here, since the first and second light receiving units are connected in series, various amplifying means can be used. For example, by using a bipolar transistor, the circuit scale of the photodetector can be reduced and the cost can be reduced. be able to. A reverse bias is applied to the first and second light receiving sections.
As the depletion layer region of each light receiving section expands, light sensitivity is high.
Degree. Also, the junction capacitance is reduced and the frequency characteristics are improved.
It is.

[0014] According to the second aspect of the present invention, the first aspect is provided.
Amplifying means in the photodetector of the first aspect is a semiconductor of the first conductivity type.
It is assumed that an amplifier including a plurality of impurity regions formed on a substrate is provided.

Further, in the invention according to claim 3, in the photodetector according to claim 2, at least one of the plurality of impurity regions constituting the amplifier has a depth of the first, second, and second impurity regions. It is assumed that the depth is equal to the depth of at least one of the third impurity regions.

According to the third aspect of the present invention, the diffusion step for integrating the first and second light receiving units and the amplifier is facilitated.

Here, a solution implemented by the invention of claim 4 is that, as a photodetector, a first impurity of the second conductivity type constituted by an epitaxial layer formed on a semiconductor substrate of the first conductivity type. A first light receiving portion including a region and a second impurity region of a first conductivity type formed on the first impurity region; a semiconductor substrate of the first conductivity type; and a first light receiving portion formed on the semiconductor substrate. A second impurity-type third impurity region constituted by the epitaxial layer, having a light detection characteristic different from that of the first light receiving portion, and being connected in series with the first light receiving portion; A light receiving portion, an isolation region for separating the epitaxial layer into the first impurity region and the third impurity region, and a first connection portion between the first light receiving portion and the second light receiving portion. And the difference current of the photocurrent generated in the second light receiving portion And those with an amplifying means for amplifying by force.

According to the fourth aspect of the present invention, in addition to the function of the first aspect of the present invention, the first impurity region and the third impurity region can be uniformly formed at a low concentration by using an epitaxial layer. The lifetime of carriers generated by light irradiation is extended. As a result, the light absorptance increases and the light sensitivity becomes high.

According to the fifth aspect of the present invention, in the fourth aspect,
The photodetector, further comprising an amplifier forming region constituted by the epitaxial layer and separated from the first and third impurity regions by an isolating region, wherein the amplifying means is formed in the plurality of amplifier forming regions. And an amplifier composed of the impurity regions described above.

According to the fifth aspect of the present invention, the amplifier layer is formed by separating the epitaxial layer by the separation region, and an amplifier including a plurality of impurity regions is formed in the amplifier formation region. Low noise and low cost can be realized.

According to a sixth aspect of the present invention, in the photodetector of the fifth aspect, the amplifier is a bipolar transistor in which a base region is connected to a connection portion between the first light receiving portion and the second light receiving portion. And the depth of the base region is equal to the depth of the second impurity region.

According to the sixth aspect of the present invention, the process for integrating each light receiving section and the amplifier becomes easy.

According to the seventh aspect of the present invention, in the fourth aspect,
In this photodetector, a reverse bias voltage is applied to the first and second light receiving units.

According to the seventh aspect of the present invention, since a reverse bias is applied to the first and second light receiving portions, the depletion layer region of each light receiving portion is widened and the light sensitivity is high. Further, the junction capacitance is reduced and the frequency characteristics are improved.

[0025] According to the invention of claim 8, the above-mentioned claim 1 is provided.
Alternatively, in the photodetector of 4, the wavelength band for performing photodetection is set by the area ratio between the first light receiving unit and the second light receiving unit.

According to the eighth aspect of the present invention, it is not necessary to change the concentrations and depths of the first to third impurity regions in order to set the wavelength band in which the light is detected. The wavelength band can be easily set by the area ratio with the part. For example, when the area ratio between the first light receiving unit and the second light receiving unit is set so that the light sensitivity of 800 nm or more becomes 0 or less, the detected light amount is the light amount in the wavelength band of 400 nm to 800 nm. Can be detected close to the relative luminous efficiency.

According to the ninth aspect of the present invention, in the first aspect,
Alternatively, in the photodetecting device of 4, the surface shapes of the first and second light receiving units are interdigitated.

According to the ninth aspect of the present invention, even when a spot light or the like smaller than the area of each light receiving section is irradiated, it is possible to detect the amount of light in the wavelength band to be detected.

Here, the solution means of the invention of claim 10 is that, as a photodetecting device, a first light receiving portion and a second light receiving portion connected in series, and a light receiving device in parallel with the second light receiving portion. A third light-receiving unit connected and having a dark current characteristic equivalent to that of the first light-receiving unit and shielded from light, and a dark current connected in parallel with the first light-receiving unit and equivalent to the second light-receiving unit A fourth light-receiving unit having characteristics and shielded from light, and a difference current between photocurrents generated in the first and second light-receiving units from a connection between the first light-receiving unit and the second light-receiving unit. And amplifying means for inputting and amplifying the input.

According to the tenth aspect, the dark current generated from the first light receiving section is canceled by the dark current generated from the third light receiving section, and the dark current generated from the second light receiving section is changed to the fourth light receiving section. Offset by the dark current generated from the part. In addition, since the third and fourth light receiving sections are shielded from light, the light detection characteristics of the entire photodetector are not affected. Therefore, it is possible to prevent the generation of the offset potential due to the dark current flowing through each light receiving unit.

According to the eleventh aspect of the present invention, in the photodetector of the tenth aspect, an equivalent reverse bias voltage is applied to the first to fourth light receiving units.

[0032]

[0033]

Moreover, solutions of the invention is taken as claimed in claim 1 2, the first impurity region and the front Symbol of the second conductivity type which is constituted by an epitaxial layer formed on a first conductivity type semiconductor substrate a A first light receiving portion including a second impurity region of a first conductivity type formed on one impurity region; a semiconductor substrate of the first conductivity type; and the epitaxial layer formed on the semiconductor substrate. A second light-receiving section, comprising a second impurity-type third impurity region having a different light detection characteristic from the first light-receiving section and connected in series with the first light-receiving section; A base region is formed in the epitaxial layer separated by the first and third impurity regions and the separation region, and the base region is connected to a connection between the first light receiving unit and the second light receiving unit. With bipolar transistor The method for manufacturing a photodetector for manufacturing the photodetector includes a step of simultaneously forming a base region of the bipolar transistor and the second impurity region in the same diffusion step.

[0035] According to the present invention 1 2, when integrating the respective light receiving portions and the bipolar transistor, it is possible to facilitate the diffusion process, also suppressed the increase in the diffusion process.

[0036]

Embodiments of the present invention will be described with reference to the drawings. In the following embodiment,
The description will be made on the assumption that the first conductivity type is P-type and the second conductivity type is N-type.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
It is a figure showing composition of a photodetection device concerning an embodiment. In FIG. 1, PD ₁ is a first light receiving portion, PD ₂ is a second light receiving portion, 1, 2, and 9 are wirings, 3 is a P-type semiconductor substrate, 4 is an N-type first impurity region, Is a P-type second impurity region, 6 is an N-type third impurity region, 7 is a P-type isolation region, and 8 is amplification means.

The photodetector according to the present embodiment has the first light receiving portion PD ₁ , the second light receiving portion PD _2, and the amplifying means 8 as main components. The first light receiving portion PD ₁ is an N-type first impurity region 4 (surface concentration = 10 ⁻¹⁶ cm ⁻² or less, deeply formed in a P-type semiconductor substrate 3 containing low-concentration phosphorus.
A depth of the impurity region = 3 μm or more, and a P-type second impurity region 5 (surface concentration = 10 ⁻¹⁸ cm ⁻²⁾ formed shallowly containing boron on the surface of the N-type first impurity region 4. that's all,
(Depth of impurity region = 2 μm or less), and has a peak sensitivity wavelength of 560.
nm.

The second light receiving portion PD ₂ is composed of a P-type semiconductor substrate 3 and an N-type third impurity region 6 (surface concentration) deeply formed in the P-type semiconductor substrate 3 with a low concentration of phosphorus. = 10
^-16 cm ^-2 or less, impurity region depth = 3 μm or more), and has a peak sensitivity wavelength of 880 nm.

Then, the P-type second light-receiving portion PD ₁
Is connected to the N-type third impurity region 6 of the _second light receiving portion PD ₂ by the wiring 9.
Two photodiodes (light receiving section PD ₁ , light receiving section P
D ₂ ) are connected in series, and the connection is connected to the amplification means 8. As will be described in the second embodiment, if the amplifying means 8 is constituted by a bipolar transistor, a circuit as shown in FIG. 7 is obtained.

FIG. 2 is a diagram showing light detection characteristics of the light detection device according to the present embodiment shown in FIG. In FIG. 2, the vertical axis is the photocurrent (nA), the horizontal axis is the light wavelength λ (nm),
First light detection characteristics of the light-receiving portion PD ₁ 10, 11 light detection characteristics of the second light-receiving portion PD _2, 12 is a light detection characteristics of the entire optical detection device shown in FIG. Further, 13 is a light detection characteristics which are estimated when the second area of the light receiving portion PD ₂ doubles. Note that there is a relationship between the photocurrent on the vertical axis and the photosensitivity (photocurrent = photosensitivity × optical power × area of light receiving unit). Further, in the present embodiment, (the first area of the light receiving portion PD ₁₎ :( second area of the light receiving portion PD ₂₎ = 5: 1 to.

The operation of the photodetector according to this embodiment will be described below with reference to FIGS.

In this photodetector, the wiring 1 is connected to a positive power supply (positive reference voltage) _Vcc , the wiring 2 is connected to the ground GND, and the potential of the wiring 9 is set to a potential between _Vcc and GND. And the first light receiving unit PD ₁ and the second light receiving unit PD
Reverse bias is applied to each of ₂ . When light is applied to the first light receiving unit PD ₁ and the second light receiving unit PD ₂ , the first light receiving unit PD ₁ has a photocurrent I ₁ according to the light detection characteristic 10 having a peak at λ = 560 nm. Occurs, and the second light receiving portion P
Light detection characteristics 11 in D ₂ with a peak lambda = 880 nm
Photocurrent I ₂ is generated in accordance with the. The difference current I ₃ between the photocurrents I ₁ and I ₂ is output from the connection between the _first light receiving unit PD ₁ and the second light receiving unit PD _2, and is amplified by the amplifying unit 8.

[0044] The first light detection characteristics 10 of the light-receiving portion PD ₁ of the optical wavelength at the intersection of the second light-receiving portion PD light detection characteristics 11 ₂ is 880 nm. Therefore, the first light receiving unit PD
_The photocurrent generated by the light component of λ = 880 nm or more in the photocurrent generated in ₁ is canceled by the photocurrent generated by the light component of λ = 880 nm or more in the photocurrent generated in the _second light receiving unit PD2. Therefore, the differential current I _3, it is possible to obtain a current proportional to the amount of light in a wavelength band corresponding to the light detection characteristics 12 of the entire inner photodetector of the irradiated light.

According to the present embodiment, the first and second light receiving sections PD ₁ and PD ₂ are connected in series, and the connecting section is connected to the amplifying means 8.
, A transimpedance type amplifier composed of a bipolar transistor and two transistors (Japanese Patent Laid-Open No. 57-140).
053 and FIG. 1 of JP-A-57-142031), a transimpedance amplifier using FET (National Technical Report Vol.
o.1 Feb.1988, p36), single power supply type operational amplifier (AN
1358, AN6500, etc.) can be used, and the circuit scale of the photodetector can be reduced.

Further, in the present embodiment, the first light receiving portion PD ₁ and the second light
Since a reverse bias each light-receiving portion PD ₂ of is applied,
The light sensitivity of each of the light receiving sections PD ₁ and PD ₂ becomes higher than the 0 bias state, and the junction capacitance is reduced and the frequency characteristic is improved.

Further, by changing the area ratio between the _first light receiving portion PD ₁ and the second light receiving portion PD ₂ , the wavelength band of the light to be detected can be easily changed. For example, the first light receiving portion PD ₁ and the second area ratio of the light-receiving portion PD ₂ to the second area of the light receiving portion PD ₂ doubling 5: a is set to 2.
At this time, in FIG. 2, the light detection characteristic of the _second light receiving unit PD2 is as shown by 13, and the light wavelength at the intersection with the light detection characteristic 10 of the _first light receiving unit PD1 is from 880 nm to 80.
It changes to 0 nm. For this reason, the wavelength band of the light to be detected can be set to 400 nm to 800 nm, the sensitivity to infrared light is sufficiently low, and brightness close to human relative luminosity can be detected.

[0048] Figure 3 is a plan view showing an example of the first light-receiving portion PD ₁ and the second arrangement of the light-receiving portion PD ₂ configuration in this embodiment. As shown in FIG. 3, the first light receiving unit PD ₁
When the second and the light-receiving portion PD ₂ are arranged convoluted with each other in comb shape. For this reason, each light receiving section PD ₁ , PD ₂
Can be detected even when a spot light or the like smaller than the area is irradiated.

[0049] Figure 4 is a plan view showing another example of the first light-receiving portion PD ₁ and the second arrangement of the light-receiving portion PD ₂ configuration in this embodiment. As shown in FIG. 4, the first light receiving unit PD
Even ₁ are arranged convoluted with each other in the second shape and the light-receiving portion PD ₂ is curved, the same effect as the arrangement shown in FIG. 3 is obtained. The arrangement shown in FIGS. 3 and 4 is an example, and the first light receiving unit PD ₁ and the second light receiving unit PD
The same effect can be obtained with other arrangements as long as the _two are arranged in a mutually intricate manner.

(Second Embodiment) Next, a second embodiment of the present invention will be described. The photodetector according to the present embodiment is configured such that the amplifying means 8 in the photodetector according to the first embodiment shown in FIG. 1 is constituted by a bipolar transistor.

FIG. 5 is a sectional view showing the structure of a photodetector according to a second embodiment of the present invention. In FIG.
D ₁ is a first light receiving unit, PD ₂ is a second light receiving unit, 27 is a bipolar transistor, and wiring is omitted. 20 is a P-type semiconductor substrate, 21 is an N-type first impurity region, 22 is a P-type second impurity region, 23 is an N-type third impurity region, and 24 is a bipolar transistor 27.
Is the base region (P type) of the bipolar transistor 27. First light receiving unit PD
₁ is a photodiode consisting of N-type first impurity region 21 and the P-type second impurity region 22. in the second light receiving portion PD ₂ includes a first semiconductor substrate 20 and the N-type P-type 3 is a photodiode including the third impurity region 23.

FIG. 7 is a circuit diagram showing a circuit configuration of the photodetector shown in FIG. As shown in FIG. 7, the first and the light-receiving portion PD ₁ and the second light receiving portion PD ₂ are connected in series, the reverse bias respectively is applied. Connecting portions of the first and the light-receiving portion PD ₁ and the second light receiving portion PD ₂ is connected to the base of the transistor T _r1. When light in the light detecting device is irradiated, the first photocurrent I ₁ flows through the light-receiving portion PD _1, the optical current I ₂ flows in the second light receiving portion PD _2, is the difference current I ₃ flows to the base of the transistor T _r1, it can be obtained in proportion to the amount of light in a wavelength band to be detected current.

According to the present embodiment, since the amplifier is constituted by the bipolar transistor 27, each light receiving section and the amplifier can be integrated, and the circuit scale of the photodetector can be reduced.

In this embodiment, the diffusion step can be easily performed by making the depth of the P-type second impurity region 22 of the first light receiving portion PD ₁ equal to the depth of the base region 25 of the bipolar transistor 27. Can be
Further, the first impurity region 21 and the third impurity region 2
By making the depth of 3 equal to the depth of collector region 24 of bipolar transistor 27, the diffusion process can be facilitated. Thereby, each light receiving section PD ₁ , P
The integration of D ₂ and the bipolar transistor 27 as an amplifier is facilitated.

Next, a method for manufacturing the photodetector according to this embodiment will be described. The first impurity region 21 and the third impurity region
Impurity region 23 is formed at the same time in a diffusion step of forming collector region 24 of bipolar transistor 27, and second impurity region 22 is formed
7 are simultaneously formed in the diffusion step of forming the base region 25. Thereby, each of the light receiving sections PD ₁ and PD ₂ is formed at the same time when the amplifier (bipolar transistor 27) is formed, and it is possible to suppress an increase in a diffusion step due to integration. In the bipolar transistor 27, the P-type semiconductor substrate 20 is doped with an N-type impurity to form a collector region 24, the collector region 24 is doped with a P-type impurity to form a base region 25, and the base region 25 is formed. It is made by doping N-type impurities to form an emitter region (not shown).

(Third Embodiment) Next, a third embodiment of the present invention will be described.

FIG. 6 is a sectional view showing the structure of a photodetector according to a third embodiment of the present invention. In FIG. 6, PD
₁ is a first light receiving unit, PD ₂ is a second light receiving unit, and 40 is a bipolar transistor as amplifying means. Also, 3
0 is a P-type isolation region, 31 is a P-type semiconductor substrate, 32 is an N-type first impurity region made of an epitaxial layer, 3
3 is a P-type second impurity region, 34 is an N-type third impurity region made of an epitaxial layer, 35, 36, and 37 are wirings, 38 is a P-type impurity region, and 39 is an amplifier formed of an epitaxial layer. This is an N-type impurity region as a region. P-type impurity region 38 becomes a base region of bipolar transistor 40, and N-type impurity region 39 becomes a collector region of bipolar transistor 40.

The photodetector according to the present embodiment has a first light receiving portion PD ₁ , a second light receiving portion PD ₂ and a bipolar transistor 40 as main components, and a first light receiving portion PD _1.
And the second light receiving section PD ₂ , the first and second light receiving sections PD ₁ , P
D ₂ and bipolar transistor 40 are separated by separation region 30.

The first light receiving portion PD ₁ is formed on a P-type semiconductor substrate 31 by using an epitaxial process, and is formed deeply in an N-type first impurity region 32 (surface) containing a low concentration of phosphorus. Concentration = 10 ⁻¹⁶ cm ⁻² , depth of impurity region =
5 μm) and a P-type second impurity region 33 formed shallowly containing boron on the surface of the N-type first impurity region 32.
(Surface concentration = 10 ⁻¹⁸ cm ⁻² , depth of impurity region = 2 μ)
m), and has a peak sensitivity wavelength of 560 nm.

The second light receiving portion PD ₂ is formed of a P-type semiconductor substrate 31 and an N-type third impurity region formed by utilizing the epitaxial process and deeply containing low-concentration phosphorus. 34 (surface concentration = 10 ⁻¹⁶ cm ⁻² , depth of impurity region = 5 μm), and has a peak sensitivity wavelength of 880 nm.

Then, the second impurity region 33 of the _first light receiving portion PD ₁ and the third impurity region 3 of the _second light receiving portion PD ₂
4 is connected to the base region 38 of the bipolar transistor 40 by connecting the first and second light receiving units PD ₁ and PD ₂ in series by connecting them with an aluminum wiring 35. The circuit configuration of the photodetector shown in FIG. 6 is as shown in FIG. 7, similarly to the photodetector according to the second embodiment.

Further, the first light receiving portion P in the present embodiment
D ₁ and second arrangement of the light-receiving portion PD _2, as in the first embodiment, as shown in FIG. 3 or FIG. 4, the first light receiving portion PD ₁ and the second and the light-receiving portion PD ₂ Are arranged in an intricate shape.

The main difference from the first embodiment is that an N-type first impurity region 32, an N-type third impurity region 34, and an N-type fourth impurity region 40 are formed by an epitaxial layer.
That is, they are separated by the separation region 30. The isolation region 30 is a P-type impurity region and is formed so as to reach the semiconductor substrate 31 from the N-type epitaxial layers (32, 34, 39).

The operation of the photodetector shown in FIG. 6 is the same as that of the first embodiment. Connect the wire 37 with connecting wires 36 to the positive supply V _cc to ground GND, it is applied respectively a reverse bias to the first and the light-receiving portion PD ₁ second light receiving portion PD _2. First light receiving unit PD ₁ and second light receiving unit PD ₂
When light is irradiated to, the first light receiving portion PD ₁ lambda = 56
Photocurrent I ₁ is generated in accordance with the light detection characteristics with a peak 0 nm, the second light-receiving portion PD ₂ photocurrent I ₂ is generated in response to the light detection characteristics with a peak lambda = 880 nm, the light differential current I ₃ of the current I ₁ and I ₂ is amplified by the bipolar transistor 40. Therefore, the same effects as those of the first embodiment can be obtained in this embodiment.

Further, in the present embodiment, the first light receiving portion P
N-type first impurity region 32 of D ₁ and second light-receiving portion P
Since the N-type third impurity region 34 of D ₂ can be uniformly formed at a low concentration at the same time by using an epitaxial layer, the lifetime of carriers generated by light irradiation can be extended, and light absorption can be achieved. The efficiency is higher and the light sensitivity is higher.

Further, since the bipolar transistor 40 is formed as an amplifier in the N-type impurity region 39 formed of the epitaxial layer separated by the separation region 30, the photodetector can be easily integrated and the circuit scale can be reduced. In addition, noise and cost can be reduced.

Further, the P-type second light-receiving portion PD ₁
Of the impurity region 33 of the bipolar transistor 40
By making the depth equal to the depth of the P-type impurity region 38 serving as the base region, the diffusion process can be facilitated. Further, by making the depths of first impurity region 32 and third impurity region 34 equal to the depth of N-type impurity region 39 serving as the collector region of bipolar transistor 40, the diffusion step can be facilitated. . This facilitates integration of the light receiving units PD ₁ and PD ₂ and the bipolar transistor as an amplifier.

The method for manufacturing the photodetector shown in FIG. 6 is as follows. The first light receiving portion PD ₁ of the N-type first third impurity region 34 of the N-type impurity region 32 and the second light-receiving portion PD _2, an N-type impurity region serving as the collector region of the bipolar transistor 40 39 are formed at the same time in the epitaxial layer forming step. Then, simultaneously formed in the step of forming a P-type impurity region 38 serving as the base region of the first light-receiving portion PD ₁ of the P-type second impurity regions 33 a bipolar transistor 40. Thus, since each of the light receiving units PD ₁ and PD ₂ is formed at the same time when an amplifier (bipolar transistor) is formed, it is possible to suppress an increase in the number of diffusion steps due to integration.

In the first to third embodiments, the first conductivity type is P-type and the second conductivity type is N-type.
The same effect can be obtained when the first conductivity type is N-type and the second conductivity type is P-type.

Here, the operation of the circuit shown in FIG. 7 will be described.

The first light receiving section PD ₁ and the second light receiving section PD ₂
Connected in series with, the second anode of the light-receiving portion PD ₂ with the first cathode of the light-receiving portion PD ₁ is connected to a power supply V _cc is grounded, opposite to the light receiving unit PD _1, PD ₂ Bias is applied. The collector of the NPN transistor T _r1 is connected to the output terminal I _out, the emitter is grounded, the base is connected to the anode and a second cathode of the light-receiving portion PD ₂ of the first light-receiving portion PD _1. N
Based PN-type transistor T _r1 - when the voltage between the emitter and V _BE, first, second, respectively the light receiving unit _{PD 1, PD 2 (V cc} -V BE), the reverse bias of V _BE is applied The light sensitivity is both high.

When light is irradiated, each of the light receiving sections PD ₁ , PD
The photocurrent I ₁ in response to each of the light detection characteristics in the _2, I ₂ flows, a difference in the base of the NPN type transistor T _r1 current I ₃
(= I ₁ −I ₂ ) flows in. As a result, the output terminal I
current h _FE1 × I ₃ from _out (h _FE1 is a current amplification factor of the NPN type transistor T _r1) flows out. The magnitude of this current is proportional to the amount of light in the wavelength band set by the light receiving units PD ₁ and PD ₂ .

The circuit configuration of the photodetector according to the first to third embodiments is not limited to FIG. FIG. 8 is a circuit diagram showing another circuit configuration.

[0074] FIG. 8 (a), NPN type transistor T _r1
Instead, a PNP transistor _Tr2 is used. First the light-receiving portion PD ₁ and the second light receiving portion PD ₂ connected in series, the first anode of the light-receiving portion PD ₁ together with the second cathode of the light-receiving portion PD ₂ is connected to a power supply V _cc ground A reverse bias is applied to each of the light receiving sections PD ₁ and PD ₂ . The collector of the PNP transistor T _r2 is connected to the output terminal I _{ou t,} emitter supply V
connected to _cc, the base is connected to the cathode and the second anode of the light-receiving portion PD ₂ of the first light-receiving portion PD _1.
The base of the PNP-type transistor T _r2 - when the voltage between the emitter and V _BE, first, second, respectively the light receiving unit _{PD 1, PD 2 (V cc} -V BE), the reverse bias of V _BE is applied ,
The light sensitivity is both high.

When light is irradiated, each of the light receiving sections PD ₁ , PD
₂ , photocurrents I ₁ and I ₂ flow according to the respective photodetection characteristics, and a difference current I ₃ (=
I ₁ -I ₂ ) flows out. As a result, a current of h _FE2 × I ₃ (h _{FE 2} is a current amplification factor of the PNP transistor _Tr2 ) flows from the output terminal I _out . This current is applied to the light receiving portion P
It is proportional to the light amount in the wavelength band set by D ₁ and PD ₂ .

Further, similarly to the circuit shown in FIG. 7, since the light receiving sections PD ₁ and PD ₂ are connected in series and a reverse bias is applied, the light sensitivity is improved as compared with the 0 bias state, and the area of the light receiving section is increased. Can be reduced, and various amplifiers can be connected, so that the circuit scale can be reduced.

[0077] FIG. 8 (b), NPN type transistor T _r1
And resistors R ₁ and R ₂ . First the light-receiving portion PD ₁ and the second light receiving portion PD ₂ are connected in series, the second
The cathode of the light receiving portion PD ₂ of one connected to the power supply V _cc, the first anode of the light-receiving portion PD ₁ is grounded,
A reverse bias is applied to each of the light receiving units PD ₁ and PD ₂ . The collector of the NPN transistor T _r1 is connected to the output terminal V _out, the emitter is grounded, the base is connected to the cathode and the second anode of the light-receiving portion PD ₂ of the first light-receiving portion PD _1. Based resistor R ₁ is an NPN transistor T _r1 - is arranged between the collector resistance R ₂ is disposed between the collector and a power supply V _cc of the NPN type transistor T _r1. Reverse biases of V _BE and (V _cc −V _BE ) are applied to the first and second light receiving sections PD ₁ and PD ₂ , respectively.
The light sensitivity is both high.

When light is irradiated, each of the light receiving sections PD ₁ , PD
₂ , photocurrents I ₁ and I ₂ flow according to the respective light detection characteristics, and a voltage expressed by the following equation is output to the output terminal V _out . V _out = A + B × (I ₁ −I ₂ ) where A = (R _{1 Vcc} + (R ₂ + R ₂ h _FE ) V _BE ) / (R ₂ +
_{R 2 h FE + R 1)} B = R 1 R 2 h FE / (R 2 + R 2 h FE + R 1) where, for _{R 1, R 2, h FE} , V BE, the V _cc is a constant, A And B are constants, the voltage V _out is equal to the light receiving portion P
It is proportional to the light amount in the wavelength band set by D ₁ and PD ₂ .

Further, similarly to the circuit shown in FIG. 7, since the light receiving sections PD ₁ and PD ₂ are connected in series and a reverse bias is applied, the light sensitivity is improved as compared with the zero bias state, and Since the area can be reduced and various amplifiers can be connected, the circuit scale can be reduced, and it can be directly connected to a microcomputer or the like.

(Fourth Embodiment) FIG. 9 shows a fourth embodiment of the present invention.
It is a circuit diagram of the photodetection device according to the embodiment. 9, the first and the light-receiving portion PD ₁ and the second light receiving portion PD ₂ are connected in series, and the third light-receiving portion PD ₃ fourth light receiving portion PD
₄ are also connected in series. First light receiving unit PD ₁
The anode and the fourth anode of the light-receiving portion PD ₄ is grounded together, the cathode of the second cathode and the third light receiving portion PD ₂ of the light-receiving portion PD ₃ are both connected to the power supply V _cc.
Further, an anode of the first and fourth light receiving portion PD _1, PD ₄ of the cathode and the second and third light receiving portion PD _2, PD _3, are both connected to the base of an NPN transistor T _r1.

The resistor R ₁ is an NPN transistor T
_r1 collector of - disposed between the base, the resistance R ₂ between the collector and a power supply V _cc of the NPN type transistor T _r1, resistor R ₃ between the emitter and the GND of the NPN type transistor T _r1, respectively distribution Have been. The value of the resistor R _3, the first
Through fourth light receiving portion PD ₁ -PD ₄ in each reverse bias V _cc /
2 is applied.

The first light receiving section PD ₁ and the third light receiving section PD ₃
The equal light receiving characteristics, also the light receiving characteristic is equal to the second light receiving portion PD ₂ and the fourth light receiving portion PD _4. Here, equal light receiving characteristics mean that the depth of the impurity region and the light receiving area are equal, and the wavelength characteristics of the light receiving sensitivity and the temperature dependence of dark current and the like are equal. Further, the third and fourth light receiving portions P
The surfaces of D ₃ and PD ₄ are shielded from light.

The circuit shown in FIG. 9 is characterized in that generation of an offset potential due to dark current flowing through each light receiving section can be prevented.

In the photodetector comprising the circuit shown in FIG. 7 or FIG. 8, the dark current always flows through the first and second light receiving sections PD ₁ and PD ₂ even when the light is not irradiated. V _off occurs. Further, since the dark current increases exponentially with temperature, a high offset potential V _off is generated particularly at high temperatures.

For example, according to the circuit shown in FIG.
The dark current of the first light receiving unit PD ₁ is I _d1 , and the second light receiving unit PD
When the _second dark current and I _d2, offset potential V _off is R
₁ · (I _d1 −I _d2 ). (I _d1 -I _d2) is at room temperature 25
Tens A next in number nA, 75 ° C. at ° C., R ₁
Is several hundred MΩ, the offset potential V _off is about 500 mV at room temperature, but about 5 V at 75 ° C.
The circuit cannot operate normally.

On the other hand, according to the circuit shown in FIG. 9, the dark currents of the _first to fourth light receiving sections PD _{1 to} PD ₄ are respectively set to I
_{When d1} , _Id2 , _Id3 , and _Id4 , the offset potential V
_off is R ₁ · {( _{Id 1} −Id ₂ ) − ( _{Id 3} −Id ₄ )}. Here, the first light receiving unit PD ₁ and the third light receiving unit PD ₃
Dark current characteristics are equal, the dark current characteristic of the second light-receiving portion PD ₂ and the fourth light receiving portion PD ₄ are equal, and since the reverse bias applied to the respective light receiving portions are equal respectively, I _d1 and I _d3
Are equal, and I _d2 and I _d4 are equal. Therefore,
Theoretically, the offset potential V _off is 0V. In practice, the offset potential V _off is 10 mV at room temperature 25 ° C. and 1 m at 75 ° C.
It is about 00 mV.

As described above, according to the photodetector of the fourth embodiment, it is possible to prevent the generation of the offset potential caused by the dark current flowing through each light receiving section.

[0088]

As described above, according to the present invention, since various amplifiers can be connected to the first and second light receiving units connected in series, the circuit scale can be reduced and the cost can be reduced. Further, a diffusion process for integrating each light receiving unit and the amplifier is facilitated.

Further, the light sensitivity becomes high, and the setting of the wavelength band to be detected can be easily changed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a photodetector according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating light detection characteristics of the light detection device according to the first embodiment of the present invention.

FIG. 3 is a plan view showing the surface shapes of a first light receiving unit and a second light receiving unit of the photodetector according to the first embodiment of the present invention.

FIG. 4 is a plan view illustrating surface shapes of a first light receiving unit and a second light receiving unit of the photodetector according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a configuration of a photodetector according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating a configuration of a photodetector according to a third embodiment of the present invention.

FIG. 7 shows a photodetector according to an embodiment of the present invention.
FIG. 3 is a circuit diagram showing a circuit configuration when the amplifier is configured by a bipolar transistor.

FIG. 8 is a circuit diagram showing an example of another circuit configuration of the photodetector according to the embodiment of the present invention.

FIG. 9 is a circuit diagram illustrating a configuration of a photodetector according to a fourth embodiment of the present invention.

FIG. 10 is a diagram illustrating a configuration of a conventional photodetector.

[Explanation of symbols]

PD ₁ First light receiving section PD ₂ Second light receiving section PD ₃ Third light receiving section PD ₄ Fourth light receiving section 1, 2, 9, 35, 36, 37 Wiring 3, 20, 31 Semiconductor substrate 4, 21 , 32 First impurity region 5, 22, 33 Second impurity region 6, 23, 34 Third impurity region 7, 26 Isolation region 8 Amplifier 24 Collector region of bipolar transistor 25 Base region of bipolar transistor 27 Bipolar transistor 30 Isolation region 38 P-type impurity region 39 N-type impurity region (amplifier formation region) 40 Bipolar transistor

Continuation of the front page (56) References JP-A-2-291182 (JP, A) JP-A-63-133128 (JP, A) JP-A-5-55621 (JP, A) JP-A-55-22871 (JP, A) JP-A-63-254736 (JP, A) JP-A-5-55538 (JP, A) JP-A-63-88871 (JP, A) JP-A-2-156575 (JP, A) 5-122158 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 31/10 G02F 3/00

Claims (12)

(57) [Claims] 1. A first impurity region of a second conductivity type formed on a semiconductor substrate of a first conductivity type, and a second impurity region of a first conductivity type formed on the first impurity region. A first light receiving unit comprising: a first conductive type semiconductor substrate; and a second conductive type third impurity region formed on the semiconductor substrate, the first light receiving unit being different from the first light receiving unit. A second light receiving unit having a spectral sensitivity characteristic and connected in series with the first light receiving unit; and a first and second light receiving unit connected to the first light receiving unit and the second light receiving unit. a amplifying means for amplifying by entering the differential current of the photocurrent generated in the light receiving portion, of the semiconductor substrate, said first impurity region of the main surface
Applying a voltage between the formed part and the back surface
Therefore, a reverse bias voltage is applied to the first and second light receiving portions.
A light detection device configured to be applied. 2. The photodetector according to claim 1, wherein the amplifying means includes an amplifier including a plurality of impurity regions formed on the semiconductor substrate of the first conductivity type. 3. The photodetector according to claim 2, wherein at least one of the plurality of impurity regions constituting the amplifier has a depth of the first, second, and third impurity regions.
A photodetector characterized in that the depth is at least equal to the depth of one of the impurity regions. 4. A second conductivity type first semiconductor device comprising an epitaxial layer formed on a first conductivity type semiconductor substrate.
A first light receiving portion including: an impurity region of a first conductivity type; a second impurity region of a first conductivity type formed on the first impurity region; a semiconductor substrate of the first conductivity type; A third impurity region of the second conductivity type formed by the epitaxial layer formed on the first light receiving portion, having a light detection characteristic different from that of the first light receiving portion, and connected in series with the first light receiving portion. A second light receiving unit, a separation region separating the epitaxial layer into the first impurity region and the third impurity region, and a connection between the first light receiving unit and the second light receiving unit. And amplifying means for inputting and amplifying a difference current between the photocurrents generated in the first and second light receiving sections from the section . 5. The photodetector according to claim 4, further comprising an amplifier forming region constituted by the epitaxial layer and separated from the first and third impurity regions by an isolation region. A photodetector comprising: an amplifier including a plurality of impurity regions formed in the amplifier formation region. 6. The photodetector according to claim 5, wherein the amplifier is a bipolar transistor having a base region connected to a connection between the first light receiving unit and the second light receiving unit. A photodetector, wherein the depth of the base region is equal to the depth of the second impurity region. 7. The method of claim 4 in which a reverse bias voltage to the first and second light receiving portion is characterized in that it is configured to be applied
3. The photodetector according to claim 1 . 8. The photodetector according to claim 1, wherein a wavelength band for performing photodetection is set according to an area ratio between the first light receiving unit and the second light receiving unit. . 9. The photodetector according to claim 1, wherein the surface shapes of the first and second light receiving sections are interdigitated. 10. A first light receiving unit and a second light receiving unit connected in series, and a dark current characteristic which is connected in parallel with the second light receiving unit and has a dark current characteristic equivalent to that of the first light receiving unit; A light-shielded third light-receiving unit, a light-shielded fourth light-receiving unit connected in parallel to the first light-receiving unit, having a dark current characteristic equivalent to that of the second light-receiving unit, and blocking the light-shielding; And amplifying means for inputting and amplifying a difference current between photocurrents generated in the first and second light receiving portions from a connection portion between the light receiving portion and the second light receiving portion . 11. The photodetector according to claim 10, wherein an equivalent reverse bias voltage is applied to the first to fourth light receiving units. 12. A first impurity region of a second conductivity type formed by an epitaxial layer formed on a semiconductor substrate of the first conductivity type, and a first impurity region of a first conductivity type formed on the first impurity region. A first light receiving portion including a second impurity region; a second conductive type semiconductor substrate; and a second light receiving portion configured by the epitaxial layer formed on the semiconductor substrate.
A second light-receiving section, which comprises a third impurity region of a conductivity type and has light detection characteristics different from that of the first light-receiving section and is connected in series with the first light-receiving section; A bipolar transistor in which a base region is formed in an epitaxial layer separated by the third impurity region and the separation region, and the base region is connected to a connection portion between the first light receiving portion and the second light receiving portion. A method for manufacturing a photodetecting device, wherein the base region of the bipolar transistor and the second
Impurity regions are formed simultaneously in the same diffusion step
A method for manufacturing a photodetector, comprising: