JPH0341323A - Detecting method of light and semiconductor photosensor ic - Google Patents

Abstract

PURPOSE:To dispense with a light cut filter and thereby to obtain photosensor IC of a small chip size and low cost by taking a difference between values of photocurrents generated in different semiconductor regions and by detecting only a light of an arbitrary wavelength area therefrom. CONSTITUTION:A sensor element is formed of a shallow P-type region 1 formed in the surface, an N-type region 2 of low impurity concentration, a deep P-type region 3, an N-type region 4 of high impurity concentration provided for contact, an aluminum wiring 5 short-circuiting the P-type region in the surface and the N-type region, an aluminum wiring 6 for contact with the deep P-type region, and an insulating film 7. By taking a difference between the spectral sensitivity characteristic 8 of the shallow P-type region 1 and the spectral sensitivity characteristic 9 of the N-type region 4 of high impurity concentration provided for contact, virtually the same spectral sensitivity characteristic with the spectral sensitivity characteristic 10 of the deep P-type region 3 is obtained. By short-circuiting the shallow N-type region 1 and the N-type region 4 of high impurity concentration provided for contact, in other words, virtually the same spectral sensitivity characteristic with that of the deep P-type region 3, that is, the spectral sensitivity characteristic attained by cutting a visible light area can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photodetection method and a semiconductor photosensor IC, and particularly to a photodetection method and semiconductor photosensor IC for detecting only light in an arbitrary wavelength range. Regarding.

[Prior Art] Conventional photodetection methods and semiconductor photosensor ICs will be described using a semiconductor photosensor IC for detecting infrared light as an example.

Conventionally, a semiconductor optical sensor IC that detects infrared light has been composed of an optical sensor with sensitivity up to infrared, a visible light cut filter, and a signal processing circuit. That is, conventionally,
In this type of semiconductor optical sensor IC, infrared light is detected by irradiating the optical sensor with light whose visible light is cut off by a visible light cut filter. Here, visible light cut filters are generally known to be formed by the following three methods.

■A separate visible light cut filter is held in front of the semiconductor optical sensor.

■Use a mold material that blocks visible light as the molding material for packaging the semiconductor optical sensor IC.

■A visible light cut filter is formed on the surface of the semiconductor optical sensor IC chip.

[Problems to be Solved by the Invention] However, the visible light cut filters formed by the methods (1) to (3) above each had the following problems.

■Semiconductor optical sensor I with individual visible light cut filter
If it is held in front of C, two components are required: a semiconductor photosensor IC and a visible light cut filter.
Since materials for holding the two parts and a process for holding them are required, the cost is high. Furthermore, the required space increases, which causes an increase in chip size.

■If a molding material with visible light cutting properties is used to package a semiconductor optical sensor IC, visual inspection after molding becomes impossible. It also requires special molding material.

(2) When forming a visible light cut filter on the surface of a semiconductor optical sensor chip IC, an extra process is added during chip manufacturing, which causes an increase in costs.

The present invention has been made in view of the problems of conventional semiconductor photosensor ICs as described above, and provides a semiconductor photosensor IC that has a small chip size and can be manufactured at low cost.
It is an object of the present invention to provide a photodetection method that can obtain the following, and a semiconductor photosensor IC that uses the detection method.

[Means for Solving the Problems] A first photodetection method of the present invention is a method for detecting light having a semiconductor region 1 of a first conductivity type, a semiconductor region 2 of a second conductivity type, and a semiconductor region 3 of a first conductivity type. A light detection method using a semiconductor photosensor IC in which a sensor and a signal processing circuit are formed on the same substrate, the semiconductor region 1 of the first conductivity type and the first
The difference between the photocurrent generated in the region of the conductive type semiconductor region 3 on the side where light enters and the photocurrent generated in the second conductive type semiconductor region 2 is taken as the detected light amount. do.

In the second photodetection method of the present invention, an optical sensor having a semiconductor region 1 of a first conductivity type, a semiconductor region 2 of a second conductivity type, and a semiconductor region 3 of a first conductivity type and a signal processing circuit are mounted on the same substrate. A photodetection method using a semiconductor photosensor IC formed on the first conductivity type semiconductor region 1 and the first conductivity type semiconductor region 1.
Difference between an optical signal obtained by a photocurrent generated in the light incident side region of the semiconductor region 3 of the conductivity type and an optical signal obtained by the photocurrent generated in the semiconductor region 2 of the second conductivity type. is the detected amount of light.

In the semiconductor photosensor IC of the present invention, an optical sensor having a semiconductor region 1 of a first conductivity type, a semiconductor region 2 of a second conductivity type, and a semiconductor region 3 of a first conductivity type and a signal IA logic circuit are provided on the same substrate. In the semiconductor optical sensor rc formed in , the semiconductor region 1 of the first conductivity type, the region of the semiconductor region 3 of the first conductivity type on the side where light enters, and the semiconductor region 2 of the second conductivity type. It is characterized in that it is electrically short-circuited.

[Operations] According to the present invention, only light in a given wavelength range is detected by taking the difference in photocurrent values (or optical signals obtained by these photocurrents) generated in different semiconductor regions. There is no need for a light cut filter, and therefore it is possible to provide a semiconductor photosensor IC that has a small chip size and can be manufactured at low cost.

[Embodiment 1] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2, taking as an example a semiconductor optical sensor IC for detecting infrared light.

FIG. 1 is a schematic cross-sectional view showing a part of a sensor of a semiconductor optical sensor IC according to this embodiment. In Figure 1, 1
is a shallow P shadow region (about 1 μm thick) formed on the surface,
2 is an n-shaded region with a small impurity concentration (thickness of about 10 μm)
, 3 is a deep P shadow region (thickness of 200 μm or more), 4 is an N shadow region with a high impurity concentration for contact, 5 is an aluminum wiring that shorts the P shadow region on the surface and the N shadow region, and 6 is a thick P shadow region. Aluminum wiring makes contact with the region, and 7 is an insulating film.

Next, the reason why the semiconductor photosensor IC shown in FIG. 1 can detect infrared light without using a visible light cut filter will be explained using FIG. 2.

FIG. 2 shows the respective regions of the shallow P shadow region 1, the N shadow region 4 with a high impurity concentration for contact, and the deep P shadow region 3 when light enters the semiconductor sensor IC shown in FIG. 3 is a graph showing spectral sensitivity characteristics of output current. In the figure, 8 indicates the spectral sensitivity characteristic of the shallow P shadow region 1, 9 indicates the spectral sensitivity characteristic of the N shadow region 4 with a high impurity concentration for contact, and 10 indicates the spectral sensitivity characteristic of the deep P shadow region 3. The direction of the output current is 8.10 is the direction in which it flows out, and 9 is the direction in which it flows in.

As is clear from FIG. 2, the deep P shadow area 3 has high sensitivity only in the infrared light region, but has almost no sensitivity in the visible light region and the ultraviolet light region. It is possible to obtain output from the deep P shadow region 3 with a single sensor, but in a semiconductor optical sensor RC where the sensor and signal processing circuit are formed on the same chip, the signal processing circuit is This is impossible because current flows from the element to the deep P shadow region 3.

On the other hand, as is clear from FIG. 2, by taking the difference between the spectral sensitivity characteristic 8 of the shallow P shadow region 1 and the spectral sensitivity characteristic 9 of the N shadow region 4 with a high impurity concentration for contact, the deep P shadow region can be determined. Almost the same spectral sensitivity characteristic as the spectral sensitivity characteristic 10 of No. 3 can be obtained. That is, by shorting the shallow P shadow region 1 and the N shadow region 4 with a high impurity concentration for contact, almost the same spectral sensitivity characteristics as the deep P shadow region 3, that is, the spectral sensitivity characteristics with the visible light region cut, are obtained. be able to.

As explained above, according to this embodiment, a semiconductor optical sensor IC that detects infrared light can be realized without using a visible light cut filter, and it can be manufactured using the same process as the normal manufacturing process. Because it can be done, the cost will not be high.

In this example, the output current for infrared light is extracted by shorting the outputs from the P shadow area and the N shadow area on the front surface, but after each output is extracted and signal processing is performed, each It is also possible to detect infrared light by taking the difference between the signals. However, with this method, there is a possibility that errors may occur due to cross-matching between the two signal processing circuits, so care must be taken.

Further, when using a single sensor, output may be obtained from the thick P shadow region 3.

The case where infrared light is detected by cutting visible light has been described above, but according to the present invention, it is also possible to cut light in a wavelength range other than the visible light range and detect light in an arbitrary wavelength range. It is clearly possible.

[Effects of the Invention] As explained above, according to the present invention, it is possible to realize a semiconductor photosensor IC that detects only light in an arbitrary wavelength range without using a light cut filter, and has visible light cut characteristics. Since there is no need for a material with and a process using it, the chip size can be reduced, and
It is possible to reduce costs in the manufacturing process.

[Brief explanation of drawings]

FIG. 1 shows a semiconductor optical sensor IC according to an embodiment of the present invention.
FIG. 2 is a graph showing spectral sensitivity characteristics when the region 1.2.3 in FIG. 1 is used as a sensor. (Explanation of symbols) 1... Shallow P shadow area formed on the sensor surface, 2...
・Low density N shadow area, 3...Deep P shadow area, 4・
・Dark n-shade area for contacting the n-shade area,
5...Aluminum wiring, 6...Aluminum wiring, 7...Insulating film, 8...Spectral sensitivity when taking output from shallow P shadow area 1, 9...Dark N shadow area 4 Spectral sensitivity when output is taken from 10... Spectral sensitivity when output is taken from deep P shadow region 3. 300400 500600700800900λ(n
m) +000

Claims (3)

[Claims] (1) A semiconductor optical sensor in which an optical sensor having a semiconductor region 1 of a first conductivity type, a semiconductor region 2 of a second conductivity type, and a semiconductor region 3 of a first conductivity type and a signal processing circuit are formed on the same substrate. A photodetection method using an IC, wherein a photocurrent generated in a region of the first conductivity type semiconductor region 1 and the first conductivity type semiconductor region 3 on the side where light enters and the second conductivity type are detected. A photodetection method characterized in that the difference between the photocurrent generated in the semiconductor region 2 of the mold and the detected light amount is determined. (2) A semiconductor optical sensor in which an optical sensor having a semiconductor region 1 of a first conductivity type, a semiconductor region 2 of a second conductivity type, and a semiconductor region 3 of a first conductivity type and a signal processing circuit are formed on the same substrate. A photodetection method using an IC, comprising: an optical signal obtained by a photocurrent generated in a region of the first conductivity type semiconductor region 1 and the first conductivity type semiconductor region 3 on the side where light is incident; and an optical signal obtained by a photocurrent generated in the semiconductor region 2 of the second conductivity type, the difference between the detected amount of light and the detected light amount (3) A semiconductor optical sensor in which an optical sensor having a semiconductor region 1 of a first conductivity type, a semiconductor region 2 of a second conductivity type, and a semiconductor region 3 of a first conductivity type and a signal processing circuit are formed on the same substrate. In the IC, the first conductivity type semiconductor region 1
A semiconductor photosensor IC characterized in that a region of the semiconductor region 3 of the first conductivity type on the side where light enters and the semiconductor region 2 of the second conductivity type are electrically short-circuited.