JPH0691279B2 - Semiconductor position detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a semiconductor position detecting element (PSD) for detecting the barycentric position of incident light as an electric signal,
In particular, the present invention relates to the configuration of a semiconductor position detecting element having high stability (reproducibility) in position detection.

[Conventional technology]

Scanning readout type detectors such as CCDs and MOS type solid-state image sensors are generally used as semiconductor detectors that detect the position of incident incident light, but these scanning readout type detectors provide reproducibility of position detection. There is a possibility that it can be kept high, but the detection speed will be limited by the frame time. Aside from the scanning readout type detector, a non-scanning type semiconductor position detecting element (PSD) that does not limit the detection speed due to frame time etc. is known. This non-scanning type semiconductor position detecting element has a uniform resistance layer composed of an n-type or p-type diffusion layer on one side, and a photoelectric film layer is formed by a signal extraction electrode provided at an end of the resistance layer. The generated photocurrent is detected through the resistance layer, and the incident position signal is obtained by this. This non-scanning semiconductor position detecting element is a lateral surface on the semiconductor surface.
The photo effect is used, and the incident light position can be instantly detected.

[Problems to be solved by the invention]

In the conventional PSD, a resistive layer that also serves as a diffusion layer for forming a potential barrier is formed as uniformly as possible on one surface of the photoelectric layer, and a photoelectrode is detected by a detection electrode provided at the end of the resistive layer, The incident position signal was obtained. However,
It is difficult to keep the stability (reproducibility) of the incident position detection high because the resistance layer cannot be formed uniformly, and the stability is lacking due to conditions such as temperature changes, and the detection accuracy is considerably reduced. There were problems such as being lost.

[Means for solving problems]

The above-mentioned problems are caused by the configuration of the semiconductor position detecting element of the present invention,
That is, a photocurrent film layer that generates photocurrent by receiving light irradiation, a high resistance layer that is provided in contact with this photoelectric film layer and forms a potential barrier on one surface of the photoconductive layer, and this high resistance layer. A resistor that is provided in contact with the high resistance layer, has a resistance value lower than that of the high resistance layer, is provided with a plurality of detection electrodes or detection terminals at its outer end, and is made of a material different from that of the high resistance layer. A circuit layer and a bias electrode provided on the surface of the photocurrent film layer opposite to the surface on which the high resistance layer is provided, and an electric signal relating to the incident position of the light with which the photoelectric film layer is irradiated. It is solved by the structure of the semiconductor position detecting element for detecting.

The resistance value of the resistance circuit layer can be controlled by adjusting the line width, the film thickness, the material, or the length (by meandering or the like).

[Action]

The photocurrent generated at the light incident position of the photoelectric film layer once passes through the high resistance layer and then is injected into the resistance circuit layer at a position close to the light incident position, and the resistance between the injection position and each detection electrode is increased. The injected current reaches the distributed detection electrodes at a ratio determined by the ratio and is detected as an incident position detection signal.

〔The invention's effect〕

According to the present invention, the resistance value of the resistance layer for dividing the photocurrent is substantially reduced, and it is easy to stably manufacture the resistance circuit layer with an accurate resistance value using a stable material. It is possible to realize a semiconductor position detecting element with extremely high reproducibility in which the detected current ratio does not fluctuate due to changes and the like.

〔Example〕

Hereinafter, the present invention will be described based on examples. 1a and 1b are a perspective view and a cross-sectional view, respectively, of an embodiment of a two-dimensional, position detecting element according to the present invention. The photoelectric film layer P is electrically divided into small areas so as to be a group of small areas corresponding to each intersection of the network resistance circuit layers R _n . Each small region of the photoelectric film layer P is connected to the resistance circuit layer R _n via the high resistance film layer R _f.
To be electrically connected to the connecting conductor C _c provided at the intersection of
That is, the resistance circuit layer R _n is in contact with each of the small regions at one point having a smaller area than the small regions. High resistance film layer R _f is a resistance circuit layer
It has a higher resistance than R _n . Resistance circuit layer R _n
Bias electrode C _b for applying a bias voltage to the photoelectric layer P on the surface of the photoelectric layer P on the opposite side is provided as is provided. A photocurrent is generated in one of the partitioned photoelectric film layers that is irradiated with light, and flows into a corresponding intersection of the resistance circuit layer R _n . The photocurrent flowing into the intersection reaches the detection electrode provided at the outer end of the resistance circuit layer through the resistance circuit layer and is detected. Since the ratio of the detection current detected by each detection electrode is determined by the resistance of the circuit until reaching each detection electrode, the incident position of light can be known by calculating the detection current value. The position detection resolution in this embodiment is determined by the fineness of the mesh of the mesh resistance circuit layer.

2a and 2b are a perspective view and a sectional view, respectively, of an embodiment of a two-dimensional position detecting element according to the present invention. It has a structure in which a mesh resistance circuit layer R _n , a uniform planar high-resistance film layer R _f , and a uniform planar photoelectric film layer P are electrically joined. The resistance value of the mesh resistance circuit layer R _n is lower than the resistance value of the high resistance film layer R _f formed on one surface of the photoelectric film, for example, 10
It is created so that the resistance value is about one-half. Photoelectric film layer P
The photocurrent generated at the incident position of the light is
Reach R _f and reach the reticulated resistance circuit layer R _n through the high resistance layer. After that, it is mainly distributed according to the resistance value of the mesh resistance circuit layer R _n until reaching the detection electrode, reaches the detection electrode, and is detected as an electric signal indicating the incident position. In this type, the position signal current detected in the entire area of the semiconductor position detecting element at the detection terminal is dominated by the mesh resistance circuit having a low resistance value. Therefore, position detection with good stability (reproducibility) becomes possible. In addition, regarding the small area divided by the mesh resistance circuit, the divided individual area and the resistance circuit around it are constituted by the conventional photoelectric film layer P, the high resistance film layer R _f , and the detection electrode. The semiconductor position detecting element has the same structure as that of the semiconductor position detecting element, and the output current indicating the incident position in the region is supplied to the surrounding resistance circuit forming the detection electrode. Therefore, the position detection resolution as a whole is not governed by the fineness of the mesh of the reticulated resistance circuit layer R _n as in the configuration of FIG. 1, and practically continuous detection is possible. In this configuration, the high resistance film layer R _f formed on one surface of the photoelectric film layer P is connected in parallel with the resistance of the reticulated resistance circuit layer R _n , and the stability of position detection (reproducibility) is obtained.
Is also affected by fluctuations in the resistance value of the high resistance film layer R _f due to temperature, etc., but the resistance value of the mesh resistance circuit layer R _n is sufficiently smaller than the resistance value of the high resistance film layer R _f (for example, 1/10
The effect can be significantly reduced by selecting (degree). For example, even _if the resistance value of the high resistance film layer R _f fluctuates by 10% due to temperature change or the like, _if the resistance value of the film resistance circuit layer R _n is set to 1/10 of that of the high resistance film layer, The overall fluctuation is 1% or less, which enables extremely stable position detection. Further, as for the position in the small area in the mesh, if the resistance variation in the small area is uniform, the detection accuracy is not practically affected. Even if the position detection accuracy in the area may be reduced, it is only in that area, and is generally governed by the stability of the reticulated resistance circuit, and the error may be integrated over the entire area. Since it does not exist, the influence on the overall accuracy is significantly reduced and high reproducibility can be maintained.

Although the reticulated resistance circuit layer has a square lattice shape in the above embodiments, it does not necessarily have to have a square lattice shape.
It is possible to correct the position detection distortion or realize a non-linear detection characteristic by making the grid shape partially different or changing the grid pitch. Figures 3a and 3b
The figure is a plan view in the case where the grid lines of the resistance circuit layer are distorted and configured, whereby the distortion of the imaging lens system can be corrected. In the position detection element in FIG. 3a, the detection electrode T _s is formed of a low resistance conductor, but in the position detection element in FIG. 3b, the detection electrode is a resistance type detection electrode T _R , and the detection terminal T ₁ , T ₂ , T ₃ , and T ₄ are provided at the four corners.

Further, although the resistance portion of the reticulated resistance circuit layer is linear, it can be made to meander.

Further, by partially changing the resistance value of the mesh resistance circuit layer, it is possible to correct the position detection distortion and realize a non-linear detection characteristic.

4 and 5 show the third and fourth aspects of the present invention, respectively.
FIG. 3 is a perspective view of an example, which is an example of a semiconductor position detecting element capable of detecting a position only in a one-dimensional direction. The ladder-shaped resistance circuit layer R _n is connected to the photoelectric film layer P via the high resistance film layer R _f.
Is provided, and a bias electrode is provided on the photoelectric film layer P.
C _b is further arranged. A detection electrode or a detection terminal is directly provided on the end portion of the resistance circuit layer R _{n in} the length direction. The portion of the resistance circuit layer R _n extending in the width direction can be formed of a conductive material having a lower resistance.

[Brief description of drawings]

FIGS. 1a and 1b are perspective views and sectional views of an embodiment of a two-dimensional detection element according to the present invention, and FIGS. 2a and 2b are perspective views of an embodiment of a two-dimensional detection element according to the present invention. And sectional views, FIGS. 3a and 3b are plan views in the case where the lattice lines of the resistance circuit layer are distorted, and FIGS. 4 and 5 are perspective views of an embodiment of the one-dimensional position detecting element according to the present invention. Fig. R _n ...... Resistance circuit layer, R _f …… High resistance film layer, P …… Photoelectric film layer, C _b …… Bias electrode, T _s …… Detection electrode, T _R …… Resistance type detection electrode, T _x1 , T _x2 , T _y1 , T _y2 , T ₁ , T ₂ , T ₃ , T ₄ ...... Detection terminal, C _c ...... Connecting conductor.

Claims (2)

[Claims] 1. A photocurrent film layer for generating a photocurrent by receiving light illumination, a high resistance layer provided in contact with the photoelectric film layer for forming a potential barrier on one surface of the photoconductive layer, It is provided in contact with the high resistance layer, has a resistance value lower than that of the high resistance layer, is provided with a plurality of detection electrodes or detection terminals at the outer end, and is made of a material different from that of the high resistance layer. An incident position of light radiated to the photoelectric film layer, which is formed of a resistance circuit layer and a bias electrode provided on the surface of the photocurrent film layer opposite to the surface where the high resistance layer is provided. A semiconductor position detecting element for detecting an electric signal relating to. 2. The photoelectric film layer and the high resistance layer are electrically divided into a plurality of small regions, and the resistance circuit layer comprises:
The small current is in contact with each small region at one point smaller than the small region, and the photocurrent generated in each small region is concentrated and injected into the resistance circuit layer. The semiconductor position detecting element according to the item (1).