JPH01115171A - Semiconductor device for incident position detection - Google Patents

Abstract

PURPOSE:To contrive the improvement of a detecting sensitivity by a method wherein a plurality of branch conducting layers formed in such a way that they are extended in the radial direction of a circle centering around a prescribed point on a substrate and with a prescribed radius are provided in such a way that they are extended from a main conducting layer formed along the circumference of the circle so as to connect a pair of position signal electrodes in a high-resistance state in the direction of the incident surface of the substrate. CONSTITUTION:A pair of position signal electrodes 2a and 2b are provided on both end parts of the incident surface of a semiconductor substrate 1 and a main conducting layer 3 is formed on the end part of the outside of the incident surface between these electrodes. This layer 3 is formed along the circumference of a circle centering around a point P. Branch conducting layers 4 are formed in the radial direction in such a way that they are extended from the layer 3 in the direction of the incident surface and these are formed into a plurality of layers at equal angles and equal intervals to one another. Accordingly, carriers generated by the incidence of light and a corpuscular beams are assembled in the layers 4, flow in the layer 3 and are subjected to resistance division according to the ratio of the lengths between the layer 3 and the position detecting electrodes. Thereby, information on an angle of rotation can be detected precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device for detecting an incident position that can output information about the incident position of light or a particle beam as a current or the like.

[Prior art] “ Conventionally, as a technology in this field, for example,
There was one shown in Publication No. 9-17288. In this conventional example, a pair of position signal electrodes are first provided at both ends of an n-type rectangular semiconductor substrate. At the center of the incident plane between these, there is a p
A p-type base conductive layer is formed, and a plurality of p-type branch conductive layers are formed extending from the base conductive layer to the incident surface.

According to this conventional example, charges generated on the incident surface due to the incidence of light or particle beams are collected in the branched conductive layers and resistance-divided in the main conductive layer. Here, since the basic conductive layer is formed to be thin, its resistance value is sufficiently high and can be set with great precision, thereby improving detection sensitivity.

[Problem that the invention seeks to solve]

However, this conventional example cannot be used for a rotation angle detector or a rotary encoder. Conventional rotary encoders and the like use a rotating disk with slits formed along its circumference, and the light passing through the slits is detected by a pair of a light emitting element and a light receiving element. For this reason, it is difficult to miniaturize the device, and the resolution remains within a certain range due to the size limit of slit formation.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a semiconductor device for detecting an incident position that is compact and can be applied to a high-resolution angle detector, a small rotary encoder, and the like.

[Means for solving problems]

A semiconductor device for detecting an incident position according to the first invention of the present application includes a semiconductor substrate of one conductivity type, a pair of position signal electrodes provided at both ends of an incident surface of the semiconductor substrate, and a pair of position signal electrodes provided at both ends of an incident surface of the semiconductor substrate. A basic conductive layer is formed along the circumference of a circle with a predetermined radius centered on a predetermined point on the semiconductor substrate so as to connect with high resistance, and It is characterized by comprising a plurality of branch conductive layers containing impurities of opposite conductivity types and extending from one another.

Further, the semiconductor device for detecting the incident position according to the second invention includes:
A semiconductor substrate of one conductivity type, a pair of position signal electrodes provided at both ends of the incident surface of this semiconductor substrate, and a predetermined point on the semiconductor substrate so as to connect the pair of position signal electrodes with high resistance. a plurality of conductive layers parallel to each other formed along the circumference of a circle with a predetermined radius, and the resistance values between both ends of each of the plurality of conductive layers are equal to each other. .

[Effect]

According to the first invention of the present application, carriers generated by the incidence of light or particle beams are collected in the branched conductive layer and flow into the basic conductive layer, thereby reducing the length ratio of the basic conductive layer to the position detection electrode. The resistance is divided according to the

Therefore, it becomes possible to accurately detect information regarding the rotation angle.

According to the second aspect of the invention, carriers generated by the incidence of light or particle beams flow into the conductive layer and are resistance-divided according to the length ratio of the basic conductive layer up to the position detection electrode. Therefore, it becomes possible to accurately detect information regarding the rotation angle.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 6 of the accompanying drawings. In addition, in the description of the drawings, the same elements are given the same reference numerals, and redundant description will be omitted.

FIG. 1 is a plan view of a semiconductor device for detecting an incident position according to a first embodiment. As shown in the figure, a pair of position signal electrodes 2a and 2b are provided at both ends of the donut-shaped entrance surface on the front side of the semiconductor substrate 1, and a base electrode is provided at the outer end of the input 11-1 between these electrodes. A conductive layer 3 is formed. This basic conductive layer 3 extends along the circumference of a circle centered on point P in the figure. A plurality of branched conductive layers 4 are formed in the radial direction so as to extend from the main conductive layer 3 in the direction of the incident plane, and these are formed in a plurality at equal angular intervals.

The detailed structure of the device of the above practical example will be explained with reference to the plan view and sectional view taken along the line A--A in FIG.

For example, on the surface side of the semiconductor substrate 1 made of n-type silicon with each side of 1 to 50 cm,
A main conductive layer 3 implanted with p-type impurities to the extent of ``'' is formed in a ring shape, and in the same process, branch conductive layers 4 are formed at a pitch of approximately 5 μm and a depth of approximately 0.5 to 1 μm. be done. 1 x 1018-1019 cm at both ends of the incident surface
Ohmic contact regions 6a and 6b implanted with p-type impurities to a depth of about -2 are formed, and these are connected to the basic conductive layer 3 described above. On top of these, for example, thermally oxidized S
An insulating film 7 made of i02 is formed, and through the openings of the insulating film 7 on the ohmic contact regions 6a and 6b,
The position signal electrode 2a is made of aluminum, for example.

Ohmic contact is made with 2b. A surface protective layer 8 made of, for example, epoxy resin is coated on these, and a wire (
(not shown) is the position signal electrode 2a.

It is bonded to 2b. On the back side of the semiconductor substrate 1, an ohmic contact layer 10 containing an n-type impurity of, for example, about lX1019 to 1020cIT+-2 is formed, and a back electrode 11 is provided in ohmic contact on the front side.

Next, the operation of the apparatus of the first embodiment described above will be explained.

For example, when an infrared spot is incident from the front surface side, it passes through the surface protection layer 8 and the insulating film 7 and reaches the incident surface of the semiconductor substrate 1 . As a result, the semiconductor substrate 1 receives electrons/
When hole pairs are generated, electrons are transferred to the ohmic contact layer 1.
0 and the back electrode 11 side, and the holes flow into the p-type branched conductive layer 4. The photocurrent caused by this hole flows through the entire calibration conductive layer 4 to the basic conductive layer 3, and is divided by a resistance ratio corresponding to the ratio of the distance (angle) from this inflow point to the position signal electrodes 2a and 2b. . Therefore, this semiconductor substrate 1
is attached to the object to be measured and a spot light is incident on the incident surface, a signal corresponding to the rotation angle is transmitted to the position signal electrodes 2a, 2.
It will be obtained from b.

Next, a modification of the first embodiment will be described with reference to FIG.

In the figure (a), the size of the semiconductor substrate 1 is halved, and the size of the semiconductor substrate 1 is 18
This is an example in which the angle of 0' can be detected. In this way, it can be installed on an object to be measured that does not rotate more than 180 degrees, so it can be used as a tilt sensor or the like.

FIG. 2B shows an example in which the branched conductive layer 4 is not provided in a portion not hit by the spotlight. If you do this,
Since the total area of the pn junction formed by the semiconductor substrate 1, the main conductive layer 3, and the branch conductive layer 4 can be reduced, leakage current can be suppressed and sensitivity can be improved. Furthermore, since the pn junction capacitance is reduced, it is suitable for high-speed, high-frequency detection.

Next, other modifications will be described with reference to FIGS. 4 and 5.

FIG. 4 is a plan view thereof, and FIG. 5 is an enlarged view thereof and a sectional view taken along line B-B and line C-C. As shown in the figure, a basic conductive layer 3 is provided at the outer end of the incident surface, and shield films 5a and 5 are provided thereon integrally with position signal electrodes 2a and 2b.
b is provided.

The shield films 5a and 5b must be conductive and are separated at the center. The effective incident area where the branched conductive layer 4 is formed is only the left half of the incident surface, and the spot light is not incident on the other ineffective incident area. Therefore, in this example, a p-type carrier trapping layer 20a is formed on the semiconductor substrate 1 in the ineffective incidence region, and a light shielding film 21b made of aluminum, for example, is further formed thereon. On the other hand, a carrier trapping layer 20a and a light shielding film 21a are also formed outside the basic conductive layer 3, and the carrier trapping layer 20a and the carrier trapping layer 20b are short-circuited to the semiconductor substrate 1 by contact electrodes 22a and 22b.

Figure 5(a) shows the position signal type +152a of Figure 4.

It is an enlarged plan view of the vicinity of 2b, and the same figure (b) and (C) are BB line and CC line sectional views, respectively. As shown,
Shield films 5a, 5b and carrier capture layers 20a, 20
b, and light shielding films 21a, 21.b. b are laminated with an insulating film 7 in between. Then, the contact electrodes 22a and 22b are connected to the semiconductor substrate 1 through the opening of the insulating film 7.
The carrier trapping layers 20a and 20b are short-circuited.

Furthermore, a surface protection layer 8 made of epoxy resin or the like is laminated on the top.

Next, the operation of the above modification will be explained.

Holes generated by the spot light incident on the effective incident area are collected in the branch conductive layer 4 and flow into the main conductive layer 3. Therefore, the photocurrent is divided by a resistance ratio depending on the angle of the inflow point.

On the other hand, electron/hole pairs are also generated in the semiconductor substrate 1 outside the effective incident area due to thermal excitation or the like. however,
The holes due to this thermal excitation are absorbed into the carrier trapping layers 20a and 20b.
and flows into the semiconductor substrate 1 via the contact electrodes 22a and 22b.

Then, similarly, the electrons generated by thermal excitation and the holes that flowed in recombine, and as a result, no carriers exist. Therefore, it becomes possible to significantly reduce so-called thermal noise.

In addition, light shielding films 21a and 21 are provided in areas other than the effective incident area.
b is provided, all light incident thereon can be eliminated. Therefore, in this respect as well, noise components can be significantly reduced.

Furthermore, since the shield films 5a and 5b are provided on the basic conductive layer 3 with the insulating film 7 interposed therebetween, the influence of charges contained in the surface protection layer 8 can be eliminated.

Specifically, the epoxy resin and the like constituting the surface protective layer 8 often contain sodium ions (Na 2 ), and when this is present, the effective cross-sectional area of the basic conductive layer 3 fluctuates. This variation in cross-sectional area becomes more significant as the impurity concentration of the basic conductive layer 3 is lowered in order to increase the resistance of the basic conductive layer 3 and improve detection accuracy. However, in the above example, the shield film 5a is conductive.

Since the basic conductive layer 3 is shielded by the conductive layer 5b, the above-mentioned inconvenience does not occur.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 6(a) is a plan view thereof, and FIG. 6(b) is a B-B
FIG. As shown in the figure, seven conductive layers 31 to 37 are formed on the semiconductor substrate 1. These conductive layers 3
Nos. 1 to 37 each have the same impurity concentration of the same conductivity type, and the thickness gradually becomes thinner toward the inside. Therefore, the resistance between both ends of each of the conductive layers 31 to 37 is the same. .

According to this example, holes generated by the incidence of the spot light flow into the p-type conductive layers 31 to 37, and are connected to the position signal electrode 2a at a resistance ratio depending on the angle of the inflow point.

It is divided into 2b. Therefore, it can be used for angle sensors, tilt sensors, etc.

The present invention is not limited to the above embodiments and modifications, and various embodiments are possible.

For example, the shield films 5g and 5b are the position signal electrodes 2a and 2.
It may be connected to the semiconductor substrate 1 without being connected to b, or may be connected to external ground via a separate electrode. Further, the materials of the semiconductor substrate 1 and the impurity concentrations of the main conductive layer 3 and the branch conductive layers 4 are not limited to those illustrated. Furthermore, the basic conductive layer 3 can also be realized by depositing polysilicon on the surface of the semiconductor substrate 1 or by forming a metal thin film such as Sn02. If the branch conductive layer 4 is connected to the main conductive layer 3 of The same applies to the invention.

〔Effect of the invention〕

As explained above in detail, in the first invention, carriers generated by the incidence of light or particle beams are collected in the branched conductive layer and flow into the basic conductive layer, and the length of the basic conductive layer to the position detection electrode is The resistance is divided according to the ratio of Therefore, it is possible to accurately detect information regarding the rotation angle, and the present invention can be applied to small-sized, high-resolution angle detectors, small-sized rotary encoders, and the like.

In addition, in the second invention, carriers generated by the incidence of light or particle beams flow into the conductive layer and are resistance-divided according to the length ratio of the basic conductive layer up to the position detection electrode. It becomes possible to detect information with high accuracy. Therefore, the present invention has the advantage that it can be applied to small-sized, high-resolution angle detectors, small-sized rotary encoders, and the like.

[Brief explanation of the drawing]

1 is a plan view of a semiconductor device for detecting an incident position according to a first embodiment of the present invention, FIG. 2 is an enlarged view and sectional view of FIG. 1, FIG. 3 is a plan view of a modified example, and FIG. 5 is an enlarged view and a sectional view thereof, and FIG. 6 is a plan view and a sectional view of the second embodiment. 1... Semiconductor substrate, 2a, 2b... Position signal electrode,
3... Basic conductive layer, 4... Branch conductive layer, 5a, 5b
...Shield M4.6 a, 6 b "Ohmic contact region, 7... Insulating film, 8... Surface protection layer, 10... Ohmic contact layer, 11...
- Back electrode, 20a. 20b...Carrier capture layer, 21a, 21b...Light shielding film, 22a, 22b...Contact electrode, 3
1-37... Conductive layer. Patent applicant Hamamatsu Photonics Co., Ltd. Representative Patent Attorney
Yoshiki Hase's Plan view of the first embodiment Fig. 1 Enlarged view and sectional view of the figure Fig. 2 Other modifications of the first embodiment Fig. 4 B C Fig. 5 Plan view of the second embodiment and cross-sectional view Fig. 6

Claims (1)

[Scope of Claims] 1. A semiconductor substrate of one conductivity type, a pair of position signal electrodes provided at both ends of the incident surface of this semiconductor substrate, and a A base conductive layer formed along the circumference of a circle having a predetermined radius centered at a predetermined point on the semiconductor substrate; A semiconductor device for detecting an incident position, comprising a plurality of branched conductive layers containing impurities of opposite conductivity types. 2. The incidence surface includes an effective incidence area and an invalid incidence area,
2. The semiconductor device for detecting an incident position according to claim 1, wherein the branched conductive layer is provided only in the effective incident area. 3. A semiconductor substrate of one conductivity type, this semiconductor base electrode, and this pair of position signal electrodes are connected at a high resistance on the circumference of a circle having a predetermined radius centered on a predetermined point on the semiconductor substrate. What is claimed is: 1. A semiconductor device for detecting an incident position, comprising a plurality of conductive layers parallel to each other, the conductive layers having mutually equal resistance values between both ends.