JPH01115170A - Semiconductor device for incident position detection - Google Patents

Abstract

PURPOSE:To make it possible to apply the title device to various applications by a method wherein at least one of a plurality of branch conducting layers formed in such a way that they are extended from a main conducting layer to an incident surface is made different from at least one of the other branch conducting layers in length. CONSTITUTION:A pair of position signal electrodes 2a and 2b are provided on both end parts on the side of the shorter side of an incident surface, which is located on the side of the surface of a semiconductor substrate 1, and a main conducting layer 3 is formed on the central part of the incident surface between these electrodes. Branch conducting layers 4 are formed 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 intervals to one another. Moreover, at least one of a plurality of these layers 4 is constituted in such a way that its length is different from that of at least one of the other layers 4. Thereby, the incident surface, in which the layers 4 exist, can take various forms and the title device can be applied to various applications.

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.

[Conventional technology]

Conventionally, as a technology in this field, for example, Japanese Patent Application Laid-open No. 5
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, p is located with a uniform cross-sectional area and a uniform impurity concentration.
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 thin, its resistance value is sufficiently high and can be set with high precision, so that detection sensitivity can be improved.

[Problem that the invention seeks to solve]

However, when this conventional example is put into practical use, since the entrance surface where the branched conductive layer exists is rectangular, the entrance surface includes an area that is not used as a detection area, and thermal excitation, etc. noise was likely to appear. Moreover, the entrance surface (semiconductor substrate) in the unused area also becomes an obstacle when attaching a light emitting element such as a laser diode.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a semiconductor device for detecting an incident position that can be widely applied to various uses.

[Means for solving problems]

A semiconductor device for detecting an incident position according to the present invention includes a - conductivity type semiconductor substrate, a pair of position signal electrodes provided at both ends of an incident surface of this semiconductor substrate, and a connection between the pair of position signal electrodes through a high resistance. A base conductive layer is formed on a semiconductor substrate so as to be formed on a semiconductor substrate, and a plurality of branch conductive layers containing impurities of opposite conductivity type are formed to extend from the base conductive layer to an incident surface. At least one is characterized in that it differs in length from at least one of the other branched conductive layers.

[Effect]

According to the present invention, since the incident surface on which the branched conductive layer exists can take various shapes, a notch or the like can be provided in the semiconductor substrate, making it possible to apply the present invention to various uses.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 5 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 an embodiment. As shown in the figure, a pair of position signal electrodes 2a and 2b are provided at both ends of the short side of the entrance plane, which is the front side of the semiconductor substrate 1.
are provided, and a basic conductive layer 3 is formed at the center of the incident surface between these. A plurality of branch conductive layers 4 are formed extending from the main conductive layer 3 in the direction of the incident plane, and are spaced from each other at equal intervals. The length of the basic conductive layer 3 is short at the central portion, and a notch 20 is formed in the semiconductor substrate 1 at that portion.

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

For example, I
A basic conductive layer 3 in which p-type impurities are implanted to a depth of about 14ca+-2 is formed to a depth of about 0.5 to 1.0 μm, and by a similar process, branch conductive layers 4 are formed at a pitch of about 5 μm to a depth of about 0.5 μm.
It is formed to a depth of about 1.0 μm. Ohmic contact regions 6a and 6b implanted with p-type impurities of approximately 1x1018 to 1019c111-2 are formed at both ends of the incident surface, and these are connected to the basic conductive layer 3 described above. On these, an insulating film 7 made of thermal oxidation 5102, for example, is formed, and ohmic contact regions 6a, 6b are formed.
Through the opening in the upper insulating film 7, ohmic contact is made with position signal electrodes 2a and 2b made of, for example, aluminum. A surface protective layer 8 made of, for example, epoxy resin is coated on these, and wires 9a and 9b are connected to the position signal electrodes 2a and 2a through the openings (not shown).
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 1×10 to 10 20 (to) −2 is formed,
A back electrode 11 is provided in ohmic contact with this surface.

Next, the operation of the apparatus of the above embodiment 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 the holes flows through the branched conductive layer 4 to the main conductive layer 3, and is divided by a resistance ratio corresponding to the ratio of the distances from this inflow point to the position signal electrodes 2a, 2b.

Here, the length of the branched conductive layer 4 is short at the upper central portion of the incident surface, and the notch 20 is formed there. Therefore, since a laser diode or the like can be attached here, the optical axis of light emitted from the light source to the object to be measured (not shown) and the optical axis of incidence from the object to the incident surface can be brought close to each other.

As a result, when the device shown in Fig. 1 is used as a tilt sensor, for example, even when the distance between the object to be measured and the sensor changes,
This can reduce errors in the tilt detection results.

Next, a modification will be explained with reference to FIG.

FIG. 4(a) is an example in which the branch conductive layer 4 is not provided in the part that is not exposed to the swatch light. In this way, the semiconductor substrate 1, the main conductive layer 3, and the branch conductive layer 4, the total area of the pn junction can be reduced, so leakage current can be suppressed and sensitivity can be improved. In addition, the pn junction capacitance is also reduced by that amount, making it suitable for high-speed, high-frequency detection. A portion of the semiconductor substrate 1 where the layer 4 is not provided may be cut out.

FIG. 3(b) shows an example in which the basic conductive layer 3 is provided at the lower end of the incident surface in the semiconductor device for detecting the incident position shown in FIG. Further, FIG. 2C shows an example in which an opening 21 is provided in the semiconductor substrate 1 at the center of the incident surface. Due to these,
Since a light source such as a laser diode can be provided in the notch 20 or the opening 21, the same effect as that shown in FIG. 1 can be obtained.

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

FIG. 4 is a plan view showing the overall configuration. As shown in the figure, a basic conductive layer 3 is provided at the lower end of the incident surface,
On top of that is a shield film 5a made of aluminum, for example.
, 5b are provided.

The shield films 5a, 5b must be conductive, and are formed integrally with the position signal electrodes 2a, 2b, respectively, and separated at the center.

The branched conductive layer 4 gradually becomes shorter from the left end in the figure toward the right side, and an ineffective incidence area exists above the branched conductive layer 4, which is not used as an effective incidence surface. A p-type carrier trapping layer 22 is provided in the ineffective incidence region,
This carrier trapping layer 22 is in ohmic contact with the semiconductor substrate 1 via a contact electrode 23 .

FIG. 5 is an enlarged view of FIG. 4 and a cross-sectional view taken along the line A--A.

As shown in the figure, shield films 5a and 5b are formed integrally with position signal electrodes 2a and 2b on the basic conductive layer 3 with an insulating film 7 in between. Further, the carrier trapping layer 22 in the invalid incidence region is formed to contain the same impurity at the same concentration as the main conductive layer 3 and the branch conductive layer 4.

Next, the operation of the apparatus shown in FIGS. 4 and 5 will be explained.

For example, when electron/hole pairs are generated by the incidence of infrared rays, only the holes are collected in the branch conductive layer 4 and flow into the main conductive layer 3. Thereby, the photocurrent is resistance-divided according to the ratio of distances from both ends of the basic conductive layer 3, and position detection is performed. At this time, since the basic conductive layer 3 is covered with the shield films 5a and 5b, the influence of the charges (for example, sodium ions) of the surface protective layer 8 does not appear on the basic conductive layer 3, and therefore the basic conductive layer Highly accurate measurement can be performed by setting 3 to high resistance.

Further, when infrared light enters the ineffective incidence region or when electron/hole pairs are generated due to thermal excitation, the holes are captured by the carrier trapping layer 22.

Here, since the carrier trapping layer 22 is short-circuited to the semiconductor substrate 1 by the contact electrode 23, the holes in the carrier trapping layer 22 flow into the semiconductor substrate 1 and recombine with electrons. Therefore, these do not become noise components.

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

For example, the shield films 5a and 5b are the position signal electrodes 2a,
It may be connected to the semiconductor substrate 1 without being connected to 2b, or may be connected to external ground via a separate electrode. Also,
Materials such as semiconductor substrate 1, basic conductive layer 3, branch conductive layer 4
The impurity concentration is also not limited to the example. Furthermore, the basic conductive layer 3 can also be realized by forming a polysilicon tube on the surface of the semiconductor substrate 1 or by forming a metal thin film such as SnO2. If branch conductive layers 4 are connected to the main conductive layer 3 made of polysilicon film or metal thin film, the photocurrent will be divided by resistance as in the embodiment.

〔Effect of the invention〕

As explained in detail above, in the present invention, the entrance plane on which the branched conductive layer exists can take various shapes, and the semiconductor substrate can be provided with notches, so it can be widely applied to various applications. It has the effect of being able to.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a semiconductor device for detecting an incident position according to an embodiment of the present invention, FIG. 2 is an enlarged view and cross-sectional view of FIG. 1, FIG. 3 is a plan view of a modified example, and FIG. 4 is another example. A plan view of a modified example of
FIG. 5 is an enlarged view and a sectional view of another modification of FIG. 4. 1... Semiconductor substrate, 2a, 2b... Position signal electrode,
3... Basic conductive layer, 4... Branch conductive layer, 5a, 5b
... Shield film, 6a, 6b... Ohmic contact region, 7... Insulating film, 8... Surface protective layer, 9a
, 9b... Wire, 10... Ohmic contact layer, 11... Back electrode, 20... Notch, 21...
...Open pores, 22...Carrier trapping layer 22゜Patent applicant Hamamatsu Photonics Co., Ltd. Representative patent attorney
Yoshiki for Hase Figure 1 Figure 3 Other variations Figure 4 Figure 5

Claims (1)

[Claims] 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 basic conductor formed on the semiconductor substrate so as to connect the pair of position signal electrodes with high resistance. layer, and a plurality of branched conductive layers containing impurities of opposite conductivity type formed to extend from the main conductive layer to the incident surface, at least one of the plurality of branched conductive layers being At least one of the branched conductive layers
A semiconductor device for detecting an incident position, characterized by having different lengths.