JP2002314117A - Lateral semiconductor photodetector of pin structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lateral semiconductor photodetector of PIN structure which is improved in sensitivity for detecting light without deteriorating its response speed. SOLUTION: A coloring matter layer 4 having a photoelectric conversion function is formed on the top surface of an I layer 15 in a light receiving region 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lateral semiconductor light receiving device having a PIN structure.

[0002]

2. Description of the Related Art In a vertical photodiode in which a pn junction surface is formed parallel to a semiconductor substrate surface, light is incident on a depletion layer through a p-layer or an n-layer.
In a lateral photodiode in which the n-junction surface is formed perpendicular to the semiconductor substrate surface, light is directly incident on the depletion layer (not through the p-layer or the n-layer). For this reason, lateral photodiodes are better than vertical photodiodes.
This is advantageous in light receiving efficiency.

Conventionally, in a photodiode,
An i layer (intrinsic layer) is provided between a p layer and an n layer to increase the thickness of a depletion layer. In a vertical photodiode having such a PIN structure, the i-layer is formed to have a thickness equal to or more than the absorption length in order to increase the light receiving sensitivity. As a result, a quantum efficiency of 70% or more can be obtained at a wavelength of about 700 nm to 870 nm.

Lateral photodiode having a PIN structure (a photodiode in which an interface between an i-layer, a p-layer, and an n-layer having a PIN structure is formed perpendicular to a semiconductor substrate surface)
For example, after a region having an extremely low impurity concentration forming an i-layer is provided in a surface layer portion of a semiconductor substrate, a p-type impurity and an n-type impurity are added to respective positions of this region at predetermined intervals from an upper surface. To form a p-layer and an n-layer, and leave an i-layer between both layers.

Therefore, in the case of a lateral photodiode having a PIN structure, the thickness of the i-layer (depth from the light incident surface)
In order to increase p, it is necessary to form the p-layer and the n-layer deeply. In order to form the p-layer and the n-layer deep while keeping the width of the i-layer (the distance between the p-layer and the n-layer) uniform in the thickness direction of the substrate, the p-layer and the n-layer on the substrate surface must be It is necessary to increase the distance. When the distance between the p-layer and the n-layer on the substrate surface is increased, the width of the i-layer increases. If the width of the i-layer is large, the movement distance of electrons generated on the p-layer side of the i-layer to reach the electrode of the n-layer increases, and the response speed decreases.

Therefore, in the lateral type photodiode having the PIN structure, as a method for increasing the light receiving sensitivity, simply increasing the thickness of the i-layer (the depth from the light incident surface) cannot be simply employed. Therefore, PIN
As a method for increasing the light receiving sensitivity of the lateral type photodiode having the structure, it is effective to provide an antireflection film on the upper surface of the i-layer to increase the efficiency of incidence on the i-layer.

[0007]

However, a lateral type photodiode having a PIN structure having an antireflection film on the upper surface of the i-layer has a problem that the response speed is low when an element for receiving a high-speed signal is used. There is. SUMMARY OF THE INVENTION The present invention has been made in view of such a problem of the related art, and it is an object of the present invention to improve the light receiving sensitivity without lowering the response speed in a lateral semiconductor light receiving element having a PIN structure.

[0008]

In order to solve the above-mentioned problems, the present invention provides a semiconductor device comprising: an interface between an i-layer having a PIN structure, a p-layer and an n-layer formed perpendicular to a semiconductor substrate surface; In a lateral type semiconductor light receiving element for detecting incident light by converting the light into a current, a dye layer having a photoelectric conversion function is provided on an upper surface and / or inside an i layer forming a light receiving region. And a lateral type semiconductor light receiving element.

[0009]

Embodiments of the present invention will be described below. FIG. 1 is a sectional view showing a photodiode corresponding to one embodiment of the present invention. FIG. 2 is a diagram showing an example of a planar shape when the photodiodes of this embodiment are formed in an array. FIG. 1 corresponds to a sectional view taken along line AA of FIG.

This photodiode is a lateral photodiode (semiconductor light receiving element) having a PIN structure formed perpendicular to the substrate surface of a silicon substrate (semiconductor substrate) 1, and forms a light receiving region 2 of an i layer 15. Part (p layer 5
And a n-layer 7), a dye layer 4 having a photoelectric conversion function is provided. A p-electrode 6 and an n-electrode 8 are formed on the upper surfaces of the p-layer 5 and the n-layer 7, respectively. The surface between the two electrodes 6, 8 is the light receiving surface 3,
The dye layer 4 is formed between the electrodes 6 and 8 via an insulating layer 91. Note that the insulating layer 91 is necessary to prevent conduction between the electrodes 6 and 8 due to electrons generated by photoelectric conversion of the dye layer 4.

An element protection layer 9 made of a silicon oxide film or the like is formed at a predetermined thickness on the upper surface of the silicon substrate 1 except for the positions of the electrodes 6, 8, the dye layer 4, and the insulating layer 91. I have. A p electrode 1 is provided on the lower surface of the silicon substrate 1.
1 is formed. This photodiode can be manufactured, for example, by the following method. First, a p-type silicon substrate 1
N-well (region with extremely low impurity concentration) 1
0 is provided. Next, the n-well 10 with a predetermined interval
The p-type impurity is added to one of the two regions, and the n-type impurity is added to the other, and diffused. Thereby, n well 10
A p-layer 5 and an n-layer 7 are formed on the n-well 10.
And the portion between n layer 7 remains as i layer 15. Then, p
After the electrodes 6 and 8 are formed on the layer 5 and the n-layer 7, an element protection layer 9 is formed.

Next, after removing the element protection layer 9 between the electrodes 6 and 8, an insulating layer 91 having a small width and contacting the electrodes 6 and 8 is formed. Alternatively, when removing the element protection layer 9,
The element protection layer 9 on the 8-side is slightly left as an insulating layer 91. Next, the dye layer 4 having a photoelectric conversion function is formed in a portion surrounded by the insulating layer 91 on the upper surface of the i-layer 15. Examples of the dye having a photoelectric conversion function include porphyrins (such as heme), phthalocyanines, and rhodopsins (such as bacteriorhodopsin). It is preferable to use a dye having high response speed and sensitivity. Examples of a method for forming the dye layer 4 include a Langmuir-Blodgett method (LB method), a spin coating method, and an ink jet method.

This photodiode applies a reverse bias voltage between the n-electrode 8 in contact with the upper surface of the n-layer 7 and the p-electrode 11 on the lower surface of the substrate 1 by connecting the power supply with the n-layer 7 side being positive. Then, by connecting the p-electrode 6 in contact with the upper surface of the p-layer 5 to the output circuit, the light incident on the i-layer 15 from the light receiving surface 3 can be converted into a current and detected. Among the light incident on the light receiving surface 3, the light absorbed by the dye layer 4 is photoelectrically converted by the photoelectric conversion function of the dye layer 4, and the generated electrons pass through the i layer 15 and the n layer 7 and the n electrode 8. Leads to. The light transmitted through the dye layer 4 enters the i-layer 15 and is photoelectrically converted by the i-layer 15 so that the generated electrons pass through the n-layer 7 and the n-electrode 8.
Leads to.

Therefore, according to this photodiode, the light receiving efficiency can be increased as compared with the photodiode in which the dye layer 4 is not formed on the i-layer 15. Also, i
The response speed is faster than that in which an antireflection film is formed on the layer 15 instead of the dye layer 4. Further, according to this photodiode, by forming the dye layer 4 by an ink-jet method or the like, it is possible to obtain an effect that it can be easily manufactured as compared with the case where an antireflection film is formed. Further, it becomes possible to detect only light of a predetermined wavelength by utilizing the wavelength selectivity of the material forming the dye layer 4. Further, the light receiving sensitivity can be easily improved by setting the absorption coefficient of the dye to be used and the thickness of the dye layer 4.

It is sufficient that the dye layer 4 is provided on the upper surface and / or inside the i-layer 15 forming the light receiving region 2. For example, as shown in FIG. 3, after the p-layer 5 and the n-layer 7 are formed, a concave portion 41 is formed in a surface portion of the i-layer 15, and in the concave portion 41 and a region surrounded by the insulating layer 91, Alternatively, the dye layer 4 may be provided only in the concave portion 41. FIG.
As shown by a two-dot chain line in FIG.
May be provided, and the i-layer 15 may also be provided on the upper surface of the dye layer 40. However, when the dye layer 4 is provided in the i-layer 15, the i-layer 15 is located between the dye layer 4 and the p layer 5 and the n layer 7.
The layer 15 must be present so that a reverse bias voltage is applied between the p layer 5 and the n layer 7.

In this embodiment, the lateral type photodiode having the PIN structure is described. However, the lateral type semiconductor light receiving element having the PIN structure of the present invention is not limited to this. It is also applied to the lateral type phototransistor and the like.

[0017]

As described above, according to the lateral semiconductor light receiving device having the PIN structure of the present invention, the light receiving sensitivity can be improved without lowering the response speed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a photodiode corresponding to an embodiment of the present invention, and is a view corresponding to a cross-sectional view taken along line AA of FIG.

FIG. 2 is a diagram showing an example of a planar shape when the photodiodes of FIG. 1 are formed in an array.

FIG. 3 is a cross-sectional view showing a photodiode corresponding to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 silicon substrate (semiconductor substrate) 10 n-well 11 p-electrode 15 i-layer 2 light-receiving region 3 light-receiving surface 4 dye layer having photoelectric conversion function 40 dye layer having photoelectric conversion function 5 p-layer 6 p-electrode 7 n-layer 8 n-electrode 9 Element protection layer 91 Insulation layer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shojiro Kitamura 3-3-5 Yamato, Suwa-shi, Nagano F-term in Seiko Epson Corporation 5F049 MA04 MB03 MB08 NA01 NA03 PA20 QA01 WA01

Claims (1)

[Claims] 1. A lateral semiconductor light receiving device in which an interface between an i-layer having a PIN structure, a p-layer, and an n-layer is formed perpendicular to a semiconductor substrate surface, and converts light incident on the i-layer into current and detects the current. A PI, wherein a dye layer having a photoelectric conversion function is provided on the upper surface and / or inside the i-layer forming a light receiving region.
Lateral type semiconductor light receiving element of N structure.