JPH0543308B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a photoelectric conversion element that outputs a signal according to the position of a light spot.

(Prior Art) A semiconductor position detection device (PSD) is known as this type of device. As shown in FIG.
are formed so as to overlap in order, and a common electrode 5 is formed on the n layer 4.
In addition, a pair of detection electrodes 6 and 7 are provided at two locations on the p layer 2 spaced apart from each other. With this configuration, when the light spot 8 is irradiated between the detection electrodes 6 and 7 as shown in the figure, each detection electrode 6 and 7
Since a current flows through the light spot 8 with a strength corresponding to the distance to the light spot 8, the irradiation position of the light spot 8 can be detected by passing each current through a signal processing circuit.For example, the irradiation position of the light spot 8 can be detected. It is used in optical processing measurement devices for industrial robots and industrial robots.

(Problem to be solved by the invention) However, since the semiconductor position detection element described above basically has a photodiode structure and does not have a current amplification function, it is inevitable that the signal processing circuit becomes considerably complicated. , it also has the disadvantage of being susceptible to noise.

Therefore, for example, when determining whether or not a light spot is incident on a predetermined position, it is necessary to provide a signal processing circuit similar to that described above, and it is also necessary to avoid the negative effects of noise. Can not.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to output a signal according to the position of a light spot, and in particular, in a configuration for determining whether or not the position of a light spot is incident on a predetermined position. It is an object of the present invention to provide a photoelectric conversion element whose processing circuit can be simplified and which can avoid being affected by noise as much as possible.

[Structure of the Invention] (Means for Solving the Problems) The photoelectric conversion element of the present invention has a collector region, a base region, and an emitter region sequentially provided on the main surface of a semiconductor substrate, and the base region is formed from the main surface side. A light receiving part capable of receiving light is used as a light spot, and an output current is obtained between the collector and emitter when the light spot is irradiated onto the light receiving part, wherein the light receiving part of the base region is provided in the collector region. a buried layer with a high impurity concentration arranged and formed so as to be divided into a plurality of parts at a predetermined interval, and a buried layer formed in electrical contact with the collector region of the main surface corresponding to each of the plurality of buried layers. It is characterized by having a plurality of collector electrodes.

(Function) When a light spot is irradiated onto the light receiving portion of the base region, a photocurrent is generated at the base-collector junction in the region irradiated with the light spot. By applying a bias between the collector and emitter, most of the output current can be obtained through the buried layer located in the region irradiated with the light spot to the corresponding collector electrode. Thereby, it is possible to detect which region of the light receiving section corresponding to the buried layer is irradiated with the light spot. In this case, the structure of the present invention is a transistor structure in which an emitter region and a collector region are provided with a base region sandwiched between them, and has a current amplification effect, so the signal processing circuit is simplified and the influence of noise It also becomes difficult to accept.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2.

11 is a silicon semiconductor substrate formed by a well-known planar technology, and this is a p-type substrate 12.
A so-called phototransistor structure is formed by overlaying an n-type epitaxial layer 13 and diffusing impurities thereon. The part of this epitaxial layer 13 that remains n-type is defined as a collector region 14, and the approximately square n ⁺ part formed in a wide area near the surface is defined as an emitter region 15, and this emitter region 15 and collector Area 1
The base region 16 is the thin p ⁺ portion between the base region 16 and the base region 16 . 17 is a SiO ₂ layer 18 on the surface of the semiconductor substrate 11
The emitter electrode is formed so as to penetrate through the emitter region 15 and continue with the emitter region 15. This emitter electrode has a substantially square shape along the four outer peripheral sides of the emitter region 15, and the wide square region surrounded by this is the light-receiving surface. When this light-receiving surface is irradiated with light, the light spot passes through the emitter region 15 and reaches the base region 16.
A current flows between the collector region 14 and the emitter region 15 depending on the amount of light. 19-22 are the first
This is a fourth collector electrode, which is located outside the four corners of the emitter electrode 17 to form a substantially L-shape as shown in FIG.
Each collector electrode 19 is in the collector region 14 of 1.
An n ⁺ region 23 having a shape similar to that of the collector electrodes 19 to 22 is provided and connected to each of the collector electrodes 19 to 22. 2
4 to 27 are the p-type substrate 11 and the epitaxial layer 13
These are the first to fourth buried layers of n ⁺ formed between the n These correspond to collector electrodes 19 to 22, respectively. Note that 28 is a p ⁺ inter-element isolation layer.

In the above configuration, when a light spot is projected onto the emitter area 15, this emitter area 1
5 and is irradiated onto the base area 16, and a large number of carriers in an amount corresponding to the amount of light are emitted onto the emitter area 1.
5 and the collector region 14. Here, the flow of the majority carriers is concentrated around the portion of the collector region 14 that is irradiated with the light spot, but the collector electrodes 19 to 22 are provided at each of the four corners of the collector region 14 and Since four divided buried layers 24 to 27 with high impurity concentration are provided in the collector region 14, the current flowing to each collector electrode 19 to 22 passes through the buried layer in the portion irradiated with the light spot. As a result, the current component flowing to the corresponding collector electrode increases. That is, if the light spot is irradiated to the center of the light receiving surface, the same current flows through each of the first to fourth collector electrodes 19 to 22.
If the light spot deviates from the center in either direction,
The current flowing through each collector electrode 19-22 becomes unbalanced depending on the position of the spot. As a result, the position on the light-receiving surface of the semiconductor substrate 11 can be detected based on the strength of the current flowing through each of the collector electrodes 19 to 22, and by using an appropriate optical system in combination, the camera can be automatically focused. Adjustment mechanisms and optical distance measuring devices for industrial robots can be configured. Furthermore, since the above configuration is a phototransistor structure and the element itself has a current amplification function, the signal processing circuit can be simplified and is less susceptible to noise. Furthermore, since it can be manufactured using a general semiconductor process, by configuring the signal processing circuit on the same chip, it is possible to achieve overall miniaturization, higher reliability, lower noise, and lower cost. .

In the above configuration, four collector electrodes and four buried layers are provided so that the position of the light spot can be detected two-dimensionally. However, the present invention is not limited to this, and the collector region is formed long and thin so that The position of the light spot may be detected one-dimensionally by providing a collector electrode and two independent buried layers on both sides of the direction. In addition, as shown in FIG. 3, deep n ⁺ diffusion 29 reaching each of the buried layers 24 to 27 may be applied in the collector region 14 to reduce the parasitic resistance of the collector. The material of 11 is not limited to silicon, but may be a compound semiconductor, and various modifications can be made without departing from the scope of the invention.

[Effects of the Invention] As described above, the present invention has a phototransistor structure as a whole, and is provided with a plurality of collector electrodes and a buried layer with a high impurity concentration divided into corresponding parts. , it is possible to provide a photoelectric conversion element that can be completed with a simple signal processing circuit and that can detect the position of a light spot without being affected by noise.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention,
Figure 1 is a longitudinal sectional view, Figure 2 is a plan view, and Figure 3 is a longitudinal sectional view.
The figures are views corresponding to Figure 1 showing different embodiments of the present invention;
FIG. 4 is a sectional view showing a conventional semiconductor position detection element. In the drawing, 11 is a semiconductor substrate, 14 is a collector region, 15 is an emitter region, 16 is a base region, 1
9 to 22 are first to fourth collector electrodes; 24 to 22 are first to fourth collector electrodes;
27 is the first to fourth buried layers.

Claims (1)

[Claims] 1. A collector region, a base region, and an emitter region are sequentially provided on the main surface of a semiconductor substrate, and the base region is used as a light receiving portion capable of receiving a light spot from the main surface side, and when the light receiving portion is irradiated with the light spot, the In the device configured to obtain an output current between a collector and an emitter, a high impurity concentration implant is arranged and formed in the collector region so as to divide the light receiving part of the base region into a plurality of parts at a predetermined interval. What is claimed is: 1. A photoelectric conversion element comprising: a layer; and a plurality of collector electrodes formed to electrically contact the collector region of the main surface in correspondence with each of the plurality of buried layers.