JPH025577A - Optical semiconductor device - Google Patents

Abstract

PURPOSE:To make a photodetecting section high in resistance so as to make a noise current small using the photodetecting section of a simple structure by a method wherein the photodetecting sections are formed in parallel with each other, using two or more low resistance regions which are arranged at a right angle with a direction of a line connected between a pair of electrodes. CONSTITUTION:In the formation of a semiconductor, an n-type high resistor 2 inside is formed of a silicon wafer of resistivity of 1000OMEGA, and low resistance P-type regions 3' are formed on the silicon wafer in such a state that they are 1X10<18>cm<-3> in surface concentration and 10mum in width, and an ion implantation is performed with 1.0X10<12>cm<-2> in dose to form a high resistance region 3 10mum in width. The space between the low resistance regions 3' and the high resistance region 3 is 10mum. In result, a photodetecting region can be made high resistive through a conventional ion implantation technique, where its resistance value, about three times as large as that of a conventional ones, can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical semiconductor device that detects the position of a -dimensional light spot.

Conventional technology In an optical semiconductor device having a PN junction, the irradiation position of a spot light irradiated on the light receiving surface of the same optical semiconductor device is determined by the difference in photocurrent from two electrodes provided at both ends of the light receiving surface. position can be detected.

As shown in the side sectional view and plan view of FIGS. 6(a) and 6(b), this device has an n-type high resistance region 2 on a semiconductor substrate 1 of a predetermined conductivity type, for example, n-type, and this surface portion This is an optical semiconductor device in which a p-required region 3 of a conductivity type different from these is provided, and the p-required region 3 has a rectangular pattern shape as shown in FIG. Anode electrodes 4, 4' are placed on the bottom surface of the substrate 1, and a cathode electrode 5 is placed on the back side of the substrate 1.

An insulating protective film 6 at the outermost portion is formed respectively.

Problems to be Solved by the Invention In actual use, spot light hits a subject, and a portion of the reflected light is irradiated onto the light-receiving surface of the optical semiconductor device. For this reason, the level of the photocurrent with respect to the irradiated light is small and the S/N ratio is poor, making it difficult to detect signals in actual use.

In order to increase the S/N, the noise current must be reduced. The noise current is generally expressed by the following formula: in: noise current, to: Borckmann's constant T: absolute temperature, B: frequency bandwidth Re(1): real part of impedance Zp In order to reduce the noise current, junction It was necessary to reduce the capacitance and increase the resistance of the light-receiving surface.

The resistance value of the light-receiving surface is determined by the amount of impurities, and it is possible to obtain the desired resistance value by controlling ion implantation, but if the dose amount during ion implantation is lowered, the variation in resistance will increase and it will be difficult to reproduce. The downside was that I couldn't get sex either.

The present invention aims to solve such problems,
The purpose is to reduce noise current by using a light receiving part with a simple structure and making the light receiving part high in resistance.

Means for Solving the Problems In order to solve the above problems, the present invention provides a light-receiving portion of an optical semiconductor device, in which a plurality of low-resistance regions are arranged parallel to each other, perpendicular to the direction connecting a pair of electrodes. and connect the electrodes in the high resistance region.

Since the resistance of the light receiving part depends on the high resistance region, by making its area small, the resistance of the light receiving part (between two electrodes) becomes large even if the amount of impurities is large. The high-resistance region is a part of the light-receiving section, but since the low-resistance layer is connected to it and spreads over the entire light-receiving region, it can be used as an optical semiconductor device.

The active light-receiving area is provided between a pair of anode electrodes, and a plurality of low resistance areas are provided in parallel with each other perpendicular to the direction connecting the same electrodes, and the above-mentioned multiple low resistance areas are formed as a high resistance area between the anode electrodes. are connected to each other to form a light-receiving surface.By using the 7 scales, a high-resistance region of the light-receiving portion can be easily formed even if the amount of impurities remains the same as before.

Characteristic 11 with little variation can be realized, and noise current 1. It is possible to reduce the amount of heat.

Embodiment FIG. 1 is a plan view showing an optical semiconductor device which is an embodiment of the present invention, and FIGS. 2 and 3 show cross-sectional views thereof in the X direction and the Y direction. 2 is a mouth-type semiconductor region, 3 is a high-resistance mouth-type semiconductor region, 3' is a low-resistance mouth-type semiconductor region, 4.4°
This is the anode electrode. In actual use, the diameter of the spot is about half a circle with respect to the Y direction of the light receiving surface, and the resolution with respect to positional displacement is also approximately the same as that of the conventional method.

When forming this semiconductor, the internal n-type high resistance 2 has a resistance of 1000Ωc! A low resistance P-type region 3'' is formed on this silicon wafer with a surface concentration of I
X 1018cm-3 width 1.0μm, and boron dose 1. Ion implantation was performed with OX 10"cn+-' to form the high resistance region 3 with a width of 10μrT1, and the spacing between the low resistance region 3° and the low resistance region 3' was 10μn1. As a result, the light receiving area was changed from the conventional one. We were able to form ions (with human technology) to have a high resistance, and were able to achieve a resistance value approximately three times that of the conventional one. Figure 4 shows the relationship between the ion implantation dose and the resistance value of the light receiving area. This is a relational diagram showing a comparison between the correlation characteristic 1-1'near of the conventional device and the correlation characteristic 8 of the present embodiment device.As can be seen from this, even in the low dose region, in the case of the present embodiment, The variation has become smaller.

Figure 5 shows another embodiment, in which the patterns are arranged with each other (different p
A pattern bone light region is created, and the same results as in the example shown in FIG. 1 can be obtained.

Effects of the Invention As described above, according to the present invention, the light-receiving portion of an optical semiconductor device is arranged in parallel to the electrode with a plurality of low-resistance regions formed, and a high-resistance region is formed perpendicular to the electrode. By connecting two electrodes, the resistance value of only the P-type region (between two electrodes) is increased using conventional ion implantation technology, and the other characteristics are the same as conventional ones (1). By being able to easily increase the resistance value, the S/N ratio increases, which is of great practical value.

[Brief explanation of the drawing]

Figure 1 shows an embodiment of the present invention.) Figure 2 is a plan view of a diode No. 1.
A sectional view in the Y direction, a sectional view in the Y direction, FIG. 4 is a diagram showing the relationship between the ion implantation amount and the resistance value of the light receiving area (between electrodes) when forming a high resistance region, and FIG. 5 is a plane view showing another embodiment of the present invention. FIG. 0 is a sectional view and a plan view of a conventional photodiode having two electrodes on the receiving surface. 1... N-type semiconductor substrate, 2... N-type high resistance semiconductor layer, 3... N-type high resistance semiconductor layer, 3
゛...P-type low resistance semiconductor layer, 4,4'...
... p-type electrode region, 5 ... n-type semiconductor substrate electrode, 6 ... insulating film, 7 ... conventional relationship diagram between ion implantation amount and interelectrode resistance, 8... Relationship diagram between ion implantation amount and interelectrode resistance of the present invention. Name of agent: Patent attorney Toshio Nakao and one other person Figure 1 Figure 40 Figure 6 Figure 5 2-71 type 1 body 1 3'-P Ri b-soui Territory book-t@Kanjo

Claims (1)

[Claims] A plurality of high resistance regions of the same conductivity type and low resistance regions of opposite conductivity type are provided on a semiconductor region of a predetermined conductivity type between a pair of electrodes, perpendicular to the direction connecting the same electrodes, and a plurality of high resistance regions of the same conductivity type are provided between the high resistance regions. An optical semiconductor device characterized in that these are connected to each other between high-resistance electrodes.