JPS63117202A - Semiconductor position detection element - Google Patents

Abstract

PURPOSE:To increase the resistance value between both anodes, by constituting the title detection element of the first and second resistor layers formed in a comb-tooth shape so that teeth are alternately arranged from both ends of a substrate and the anodes respectively connected to the base parts of said resistor layers. CONSTITUTION:The teeth 2-1-2-n, 3-1-3-n of the first and second resistor layers of an N-type substrate 1 are formed by a P<+> type diffusion layer. The base parts of the teeth of each of the resistor layers are respectively connected by the same type resistor layer and the first and second anode terminals 6, 7 are connected to the substrate 1. Further, a cathode 4 is connected to the back surface of the substrate 1. Then, when large spot beam is allowed to be incident to a luminous flux incident region so as to extend over a large number of the teeth of the resistor layers, the diodes D1, D2 generated herein are similarly distributed to each resistor layer. The photocurrent due to the diodes D1, D2 distributed flows to the respective electrodes through the resistor layers.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a semiconductor incident position detection element capable of outputting information on the incident position of light.

(Prior Art) FIG. 5 is a diagram showing a cross-sectional structure of a conventional general one-dimensional semiconductor position detection element.

A resistance layer 55 made of a P+ type diffusion layer is formed on the surface of an N type substrate 56.
is formed.

A first anode 51 and a second anode I are provided at both ends of the resistance layer 55.
and 52 are connected.

A cathode 53 is connected to the center of the back surface of an N-type substrate 56.

When light enters the substrate 56, the light generates electrons.

A hole pair is generated.

Since the resistance layer 55 is of P+ type, the diffusion layer into which this light enters is in a non-equilibrium state, and electrons are absorbed into the cathode, so holes gather near the incident light and diffuse to both anodes 51 and 52. Flow.

At this time, the current flowing to the anode 51.52 is 11°I2
is determined by the resistance ratio between both anodes, and is expressed as equation (1).

'1-1o (1-x/d) 12-1o (x/d) ++m (1+d Distance between near nodes ) In the semiconductor position detection element described above, a diffusion layer (resistance layer) 55 is provided between the first anode 51 and the second anode 52.
connected with.

Therefore, unless the voltages between both anodes are equalized,
Currents other than the 8 detection signal based on the potential difference between both anodes will flow.

When this semiconductor position detecting element is used in connection with a detection circuit, the input impedance of the detection circuit is determined by the resistance value of the resistance layer, so the input impedance of the detection circuit must be kept small, thereby avoiding the disadvantage of worsening noise characteristics. had.

When using the semiconductor position detection element for camera autofocus, in order to keep the voltage of the anode electrode constant,
A constant voltage circuit is required.

Furthermore, when the external light current (current due to incident light other than signal light) is large, there is a drawback in that detection sensitivity is limited.

When the external light current is about 4 μA, a noise current of about 0.3 PA is generated.

An object of the present invention is to provide a semiconductor position detection element that can significantly increase the resistance value between both anodes and solve the above-mentioned problems.

(Means for Solving the Problems) In order to achieve the above object, a semiconductor position detection element according to the present invention includes a substrate of a first conductivity type, and a comb-like shape formed from one end of the surface of the substrate. a first resistance layer of a second conductivity type; and a second conductivity type formed in a comb-teeth shape such that teeth are alternately arranged on the first resistance layer from the other end of the surface of the substrate. a second resistive layer; and first and second anodes connected to the bases of the first and second resistive layers, respectively;
It consists of a cathode provided on the substrate.

The substrate may be of N type and the resistive layer may be of P+ type.

The width of the region between the teeth of the first resistive layer and the second resistive layer may be within a Debye characteristic length.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings and the like.

FIG. 1 is a plan view showing an embodiment of a semiconductor position detection element according to the present invention.

FIG. 2 is a cross-sectional view of the example element in the lateral direction.

The peaks 2-1°2-2 of the first resistance layer are formed on the surface of the N-type substrate 1.
~2-01 The teeth 3-1, 3-2 to 3-n of the second resistance layer are formed by P+ type diffusion.

The bases of the teeth of each resistive layer are connected by a resistive layer of the same shape, and a first anode terminal 6. A second anode terminal 7 is connected.

In FIGS. 1 and 2, the width and spacing of the teeth of the resistive layer are exaggerated compared to other parts for ease of representation.

In this example, the width and spacing of the teeth of the resistance layer are 20 μm.

A cathode 4 is connected to the back surface of the N-type substrate 1.

FIG. 3 is an enlarged sectional view for explaining the operation of the element.

The tooth spacing of the resistance layer is 7! (20 μm in this example) is
Must be within the Debye characteristic length.

Debye characteristic length means that the concentration of non-equilibrium carriers is 1/e
is the distance at which

Pairs of electrons and holes are generated by the incidence of photons, and the holes reach the cathode and the electrons reach the teeth 3-j and 2-j of the resistive layer, respectively, reaching the second anode 7 and the first anode 6.
reach.

FIG. 4 is an equivalent circuit diagram for explaining the operation of the semiconductor position detection element.

D, , D2 are diodes formed at the incident position by the incident light, and rl and r2 are the resistance values of the resistance layer.

When a large light spot is incident such that the incident area of the light flux spans through a large number of resistive layers, the electrons generated here are similarly distributed to each resistive layer.

Photocurrent due to the distributed electrons flows to each electrode through the resistive layer, and therefore the same effect as the conventional method can be achieved.

In order to equalize the distribution to each electrode, it is preferable in terms of characteristics to fill the spaces between the teeth of the resistance layer with a depletion layer, and the distance between the electrodes is within the Debye characteristic length determined by the substrate concentration.

(Effects of the Invention) As explained in detail above, the semiconductor position detection element according to the present invention includes a substrate of a first conductivity type, and a substrate of a second conductivity type formed in a comb-like shape from one end of the surface of the substrate. a first resistance layer; a second resistance layer of a second conductivity type formed in a comb-teeth shape such that teeth are alternately arranged on the first resistance layer from n1 on the surface of the substrate; first and second anodes connected to the bases of the first and second resistance layers, respectively;
It consists of a cathode provided on the substrate.

According to the above configuration, the impedance of the semiconductor position detection element can be increased by about 4 to 5 orders of magnitude compared to the conventional one.

Therefore, a constant voltage circuit is not required at all, and it can be handled in the same way as a conventional photodiode.

It is also expected that the noise level will be on the same level as that of a photodiode.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of a semiconductor position detection element according to the present invention. FIG. 2 is a cross-sectional view of the example element in the lateral direction. FIG. 3 is an enlarged sectional view for explaining the operation of the element. FIG. 4 is an equivalent circuit diagram for explaining the operation of the semiconductor position detection element. FIG. 5 is a cross-sectional view of a conventional semiconductor position detection element. 1... Substrate 2-1. 2-2 to 2-n... Teeth 3-1 of the first resistance layer
．． 3-2 to 3-n... Teeth of second resistance layer 4... Cathode (K) 6.7... First and second anodes r1. r2...
・Resistance values Dl, D2...Diode formed by incident light Patent applicant Hamamatsu Photonics Co., Ltd. Representative Patent attorney Inoro Tsukimi 1 4b2 figure

Claims (3)

[Claims] (1) a substrate of a first conductivity type; a first resistance layer of a second conductivity type formed in a comb-like shape from one end of the surface of the substrate;
a second resistance layer of a second conductivity type formed in a comb-teeth shape such that teeth are alternately arranged on the first resistance layer from the other end of the surface of the substrate; A semiconductor position detecting element comprising first and second anodes respectively connected to the base of the resistive layer, and a cathode provided on the substrate. (2) The semiconductor position detection element according to claim 1, wherein the substrate is of N type, and the resistance layer is of P^+ type. (3) The semiconductor position detection element according to claim 1, wherein the width of the region between the teeth of the first resistance layer and the second resistance layer is within the Debye characteristic length.