JP2000091624A - Semiconductor position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor position detector with high performance. SOLUTION: This semiconductor position detector is provided with a pair of outside semiconductor areas 11 continuously provided at the both edge parts so that the resistance value per base line length directional unit length can be made smaller than that of a trunk conductive layer 2, and that an incident light can be received. The resistance per unit length in the base line length directional of the outer semiconductor region 11 is made smaller than that of the semiconductor conductive layer 2. That is, it is desired that the impurity concentration is made high, and contribution to resistance division for position detection is made small. Thus, the deterioration of position resolution can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor position detector.

[0002]

2. Description of the Related Art A semiconductor position detector disclosed in Japanese Patent Application Laid-Open No. 64-78110 divides a photocurrent generated in accordance with an incident light position by resistance, and a pair of signal extraction electrodes for extracting the divided current respectively. A photodiode region is provided on the outside to detect incident light from a very short distance.
However, when detecting the position, the signal extraction electrode blocks the incident light, so that accurate position detection cannot be performed.

Further, a semiconductor position detector shown in FIGS. 18 to 20 is also known.

FIG. 18 is a plan view of a conventional semiconductor position detector, and FIG. 19 is an AA diagram of the semiconductor position detector shown in FIG.
FIG. 20 is a sectional view taken along the arrow BB of the semiconductor position detector shown in FIG. 18. On the semiconductor substrate 1, a main conductive layer 2, a branched conductive layer 3, and a high-concentration layer 4 for signal extraction are formed, and an outer frame layer 6 and an outer frame electrode 7 surrounding the respective functional layers are provided. A layer 6 'is provided. When a reverse bias voltage is applied between the high-concentration layer 8 and the surface layers 2 and 3 via the back electrode 9 and light enters in this state, charges (hole / electron pairs) are internally generated in response to the incidence. appear. The generated charge is located at a position along the base line length direction of the basic conductive layer 2,
That is, it is output to the outside via the electrodes 5 provided at both ends thereof in inverse proportion to the resistance value.

FIG. 21 is a plan view of the semiconductor position detector when spot light is incident. When spot light is incident on the semiconductor position detector, the signal extraction electrode 5 blocks the incident light at the end of the light receiving area, so that it is difficult to improve the position detection performance, and the detectable range is expanded to the desired detection range. I can't let it.

[0006]

Therefore, if the light receiving region is extended in the base line length direction to enlarge the semiconductor position detector itself, incident light which originally would have been applied to the signal extraction electrode can be detected. . However, when the light receiving region is simply extended in the base line length direction, the semiconductor conductive layer divided by the resistance becomes longer, and conversely, the positional resolution decreases. The present invention has been made in view of such problems, and has as its object to provide a high-performance semiconductor position detector.

[0007]

In order to solve the above-mentioned problems, a semiconductor position detector according to the present invention outputs signals from both ends of a semiconductor conductive layer in accordance with an incident light position in a base line length direction on a light receiving surface. In a semiconductor position detector having a variable current value, a pair of signal extraction electrodes from which the currents are respectively extracted, and an outer semiconductor region interposed in a current path between at least one of the both ends and the signal extraction electrode. Wherein the outer semiconductor region has a smaller resistance value per unit length in the base line length direction than the semiconductor conductive layer and is provided continuously at least on one of the both ends so as to be able to receive incident light. .

According to the semiconductor position detector of the present invention, the outer semiconductor region is provided continuously outside the semiconductor conductive layer so as to be able to receive incident light. The incident light that has been applied can also be received by the outer semiconductor region, and the position of the incident light can be detected by extracting a current generated according to the light incident on the semiconductor conductive layer or the outer semiconductor region from the signal extraction electrode. it can. Further, the outer semiconductor region has a smaller resistance value per unit length in the base line length direction than the semiconductor conductive layer,
That is, since the impurity concentration is preferably high and the contribution to resistance division for position detection is small, a decrease in position resolution can be suppressed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor position detector according to an embodiment will be described below. The same reference numerals are used for the same elements or elements having the same functions, and overlapping descriptions are omitted.

(First Embodiment) FIG. 1 is a plan view of a semiconductor position detector according to a first embodiment, FIG. 2 is a cross-sectional view of the semiconductor position detector shown in FIG. FIG. 2 is a cross-sectional view of the semiconductor position detector shown in FIG. The cross-sectional view of the semiconductor position detector used for the description shows the end face.

The semiconductor position detector according to the present embodiment includes a semiconductor substrate 1 made of low-concentration n-type Si, a back-side n-type semiconductor layer 8 made of high-concentration n-type Si formed on the back surface of the semiconductor substrate 1, and It has. The surface of the semiconductor substrate 1 is rectangular.

In the following description, the direction from the back side n-type semiconductor layer 8 toward the n-type semiconductor substrate 1 is defined as the upward direction, and the extension direction of the long side of the rectangular surface of the n-type semiconductor substrate 1 is defined as the length direction (longitudinal direction). ) X, the extension direction of the short side is width direction Y, and the direction perpendicular to both length direction X and width direction Y is depth direction (thickness direction) Z. That is, the directions X, Y, and Z are orthogonal to each other.

The present semiconductor position detector includes a main conductive layer 2 formed in a semiconductor substrate 1 and extending along a length direction X. The basic conductive layer 2 is made of p-type Si, and the resistivity of the basic conductive layer 2 is lower than the resistivity of the semiconductor substrate 1. The basic conductive layer 2 has a substantially uniform impurity concentration, that is, a resistivity ρ, and extends from the surface of the n-type semiconductor substrate 1 along the thickness direction Z to substantially the same depth.

The semiconductor position detector includes a branched conductive layer 3 composed of a plurality of p-type semiconductor conductive layers extending from the main conductive layer 2 along the light receiving surface. The impurity concentration of the branched conductive layer 3 is substantially the same as the impurity concentration of the main conductive layer 2, and the length of the branched conductive layer 3 along the width direction Y is longer than the diameter of the incident light spot.

Note that the branched conductive layer 3 may be made of p-type Si having a higher concentration than the impurity concentration of the basic conductive layer 2. In other words, the resistivity of the branch conductive layer 3 is
Lower than the resistivity. In this case, the basic conductive layer 2 includes a plurality of p-type resistance regions that are continuous along the length direction X with one end of the branched conductive layers having different impurity concentrations interposed therebetween.

As described above, in order to reduce the influence on the detection accuracy of the branched conductive layer 3, it is desirable to increase the impurity concentration and reduce the resistivity. The resistivity of the layer 3 and the semiconductor conductive layer 2 are assumed to be substantially the same, and they are manufactured in the same step to shorten the manufacturing time.

The present semiconductor position detector includes a pair of outer semiconductor regions 11 formed in the semiconductor substrate 1 and connected to both ends of the main conductive layer 2. Outer semiconductor region 1
1 is made of high-concentration p-type Si. Outer semiconductor region 11
Extends from the surface of the semiconductor substrate 1 along the thickness direction Z to a position deeper than the depth of the basic conductive layer 2.

The present semiconductor position detector includes an outer frame semiconductor layer 6 formed on the outer peripheral portion of the rectangular surface of the semiconductor substrate 1. The outer frame semiconductor layer 6 is made of high-concentration n-type Si. The outer frame semiconductor layer 6 is formed in the outer edge region of the rectangular surface of the semiconductor substrate 1 to form a square shape, and the substrate surface region where the main conductive layer 2, the branch conductive layer 3, and the outer semiconductor region 11 are formed And extends from the surface of the n-type semiconductor substrate 1 to a predetermined depth along the thickness direction Z.

The present semiconductor position detector includes a semiconductor layer 6 ′ for isolating a branched conductive layer formed in a semiconductor substrate 1. The branching conductive layer isolating semiconductor layer 6 'is made of high-concentration n-type Si. The branching conductive layer separating semiconductor layer 6 ′ is formed from a plurality of n-type branching regions extending in the direction of the base conductive layer 2 along the width direction Y from inside the long side of the square outer frame semiconductor layer 6. Become. Each branch region extends from the surface of the n-type semiconductor substrate 1 to a predetermined depth along the thickness direction Z. This n-type branch region is
It is deeper than the p-type branched conductive layer 3 and is interposed between the branched conductive layers 3 and between the branched conductive layer 3 and the outer semiconductor region 11 to electrically isolate them. That is, the branch region blocks a current flowing along the length direction X between adjacent ones of the branch conductive layers 3 and between the branch conductive layer 3 and the outer semiconductor region 11.

The present semiconductor position detector comprises an n-type semiconductor substrate 1
Passivation film (insulating film) 10 covering the rectangular surface of
Is provided. It should be noted that the passivation film 10 is shown in FIG.
Is omitted. The passivation film 10 has a pair of rectangular openings for signal extraction electrodes at both ends in the length direction,
A square-shaped opening for the outer frame electrode is provided on the outer periphery.

The signal extraction electrode 5 is formed on the passivation film 1.
A pair of openings for the signal extraction electrode of 0 is formed on the outer region of the outer semiconductor region 11 so that the inner region of the outer semiconductor region 11 is exposed to incident light. It is in ohmic contact with the semiconductor region 11.

The outer semiconductor region 11 has a smaller resistance value per unit length in the base line length direction than the base conductive layer 2, that is, preferably has a higher impurity concentration. In the present semiconductor position detector, the outer semiconductor region 11 is provided continuously outside the semiconductor conductive layer 2 so as to be able to receive the incident light. Light can also be received by the inner exposed region of the outer semiconductor region 11 for incident light.

Since the outer semiconductor region 11 has a low resistance value,
When the incident light spot is applied to the main conductive layer 2 and the branched conductive layer 3, this does not contribute to the resistance division of the main conductive layer 2 and the signal current corresponding to the exact position of the incident light is reduced. The signal is output from each signal extraction electrode 5 so as to be inversely proportional to the resistance division ratio of the layer 2.

Further, since the outer semiconductor region 11 has a low resistance value, when an incident light spot is irradiated thereon, the electric charge generated in response to the photoelectric conversion is divided by the resistance in the base line length direction (X). Most of the current flows into the signal extraction electrode 5 which is the closest, without affecting it. Even in this case, the signal current corresponding to the accurate incident light position is inversely proportional to the resistance division ratio of the main conductive layer 2. The signal is output from each signal extraction electrode 5.

The present semiconductor position detector has an outer frame electrode 7 formed on an n-type outer frame semiconductor layer 6 through an opening for the outer frame electrode of the passivation film 10. Outer frame electrode 7
Are in ohmic contact with the outer frame semiconductor layer 6. The outer frame electrode 7 prevents light from entering the outer peripheral portion of the semiconductor substrate 1.
Further, a predetermined voltage can be applied between the outer frame electrode 7 and the signal extraction electrode 5.

The present semiconductor position detector has a lower surface electrode 9 formed on the lower surface of the back side n-type semiconductor layer 8. The lower electrode 9 is in ohmic contact with the back side n-type semiconductor layer 8.

A voltage between the pair of signal extraction electrodes 5 and the lower surface electrode 9 such that a reverse bias voltage is applied to a pn junction diode composed of the p-type branched conductive layer 3 and the n-type semiconductor substrate 1. And the semiconductor conductive layers 2, 3, 11
When the incident light is incident as a spot light on the light receiving surface defined by the surface region of the n-type semiconductor substrate 1 on which is formed, electron-hole pairs (charges) are generated inside the semiconductor position detector in accordance with the incident light. One flows into the branch conductive layer 3 according to the electric field inside the diffusion and diffusion and the semiconductor position detector. This electric charge flows through the branched conductive layer 3 and flows into a predetermined position of the basic conductive layer 2, and is inversely proportional to the resistance value to both ends of the basic conductive layer 2 according to the position in the longitudinal direction X of the basic conductive layer 2. The amount of charge is distributed so that the distributed charge is extracted from each signal extraction electrode 5 through both ends of the main conductive layer 2 and the outer semiconductor region 11. The position of the incident light can be detected by extracting the current generated according to the light incident on the main conductive layer 2 or the outer semiconductor region 11 from both signal extraction electrodes 5.

That is, since the ratio of the current value of the signal current output from each signal extraction electrode 5 changes according to the incident light position, the incident light position can be specified from this.

FIG. 22 shows an equivalent circuit (FIG. 22) of the ordinary semiconductor position detector (conventional example A) shown in FIG.
(A)) and an equivalent circuit (FIG. 22 (b)) of the semiconductor position detector according to the embodiment. In the figure, P indicates a current source, D indicates an ideal diode, Cj indicates a junction capacitance, Rsh indicates a parallel resistance, and Rp indicates a resistance value of the main conductive layer. The limit positions in the base line length direction where the incident light is not blocked by the signal extraction electrodes are denoted by XL and -XL. As shown in the figure, the semiconductor position detector according to the embodiment can detect the position even when light is incident on the outer semiconductor region 11, so that the position of the incident light can be detected as compared with the related art. The range can be expanded.

FIG. 23 is a graph (FIG. 23A) showing the relationship between the incident light spot position X and the signal currents I1 and I2 output from the electrode 5, and the relationship between the incident light spot position X and the position detection error. The graph shown in FIG.
(B)). In Conventional Example A, position XL or-
When light enters outside of XL, the signal current is significantly reduced due to the lack of the incident light spot. On the other hand, in the present embodiment, since the outer semiconductor region 11 functions to collect the incident light corresponding to the position of the chip, such a situation is suppressed. Further, in the present embodiment, the position detection error in this region is also reduced as compared with the conventional example A.

As described above, in the semiconductor position detector according to the present embodiment, the currents respectively output from both ends of the semiconductor conductive layer 2 in accordance with the position of the incident light in the base line length direction X on the light receiving surface. In a semiconductor position detector whose value is variable,
A pair of outer semiconductor regions 11 provided continuously at both ends so as to have a smaller resistance value per unit length in the base line length direction than the semiconductor conductive layer 2 and to be able to receive incident light; And a pair of signal extraction electrodes 5 arranged at positions where the generated current is extracted via the outer semiconductor region 11. The outer semiconductor region 11 may be provided on only one of the both ends, and is provided in a current path between at least one of the two ends and the signal extraction electrode.

When the light receiving region of the conventional semiconductor position detector is simply extended along the base line length direction (X), the semiconductor conductive layer divided by the resistance becomes longer, and conversely, the position resolution decreases. However, in the present embodiment, the outer semiconductor region 11 has a smaller resistance value per unit length in the base line length direction than the semiconductor conductive layer 2, that is, preferably, the impurity concentration thereof is high and the position of the outer semiconductor region 11 is high for position detection. Does not contribute much to the resistance division, so that a decrease in the position resolution can be suppressed.

(Second Embodiment) FIG. 4 is a plan view of a semiconductor position detector according to a second embodiment, FIG. 5 is a sectional view taken along the line AA of the semiconductor position detector shown in FIG. 4, and FIG. FIG. 6 is a cross-sectional view of the semiconductor position detector shown in FIG.

The present embodiment is different only in that a semiconductor conductive layer 12 is used instead of the semiconductor conductive layers 2 and 3. The semiconductor conductive layer 12 has a zigzag shape obliquely intersecting the position detection direction (X) in the light receiving surface. Carriers generated in response to incident light are collected on the semiconductor conductive layer 12 without intervening indirect light collecting means such as a branched conductive layer, so that direct position detection can be performed.

(Third Embodiment) FIG. 7 is a plan view of a semiconductor position detector according to a third embodiment, FIG. 8 is a sectional view taken along the line AA of the semiconductor position detector shown in FIG. 7, and FIG. FIG. 8 is a sectional view taken along the line BB of the semiconductor position detector shown in FIG. 7.

The semiconductor position detector of the present embodiment is different from the semiconductor position detector of the second embodiment in that its semiconductor conductive layer 1
The semiconductor conductive layer 13 is obtained by changing only the shape of No. 2.

That is, in the present semiconductor position detector, the semiconductor conductive layer 13 is composed of a plurality of linear portions extending perpendicular to the position detection direction (X) in the light receiving surface, and a pair of adjacent linear portions. And a connection portion that alternately connects only one end along the position detection direction. Also in the present embodiment, the carriers generated according to the incident light are collected by the semiconductor conductive layer 13 without intervening indirect light collecting means such as a branched conductive layer.

(Fourth Embodiment) FIG. 10 is a plan view of a semiconductor position detector according to a fourth embodiment, FIG. 11 is a sectional view taken along the line AA of the semiconductor position detector shown in FIG. 10, and FIG. 1
FIG. 3 is a cross-sectional view of the semiconductor position detector shown in FIG.

The semiconductor position detector of the present embodiment is different from the semiconductor position detector of the second embodiment in that its semiconductor conductive layer 1
The semiconductor conductive layer 14 is obtained by changing only the shape of No. 2.

That is, in the present semiconductor position detector, the semiconductor conductive layer 14 is composed of a plurality of linear portions extending in a stripe shape along the position detection direction (X) in the light receiving surface. The semiconductor device further includes a semiconductor layer 15 for isolating a semiconductor conductive layer formed in the semiconductor substrate 1. The semiconductor layer 15 for isolating the semiconductor conductive layer is made of high-concentration n-type Si.
It intervenes between them to block current flowing between their neighbors. Also in the present embodiment, the carriers generated according to the incident light are collected on the semiconductor conductive layer 14 without intervening indirect light collecting means such as a branched conductive layer.

(Fifth Embodiment) FIG. 13 is a plan view of a semiconductor position detector according to a fifth embodiment, and FIG. 14 is a cross-sectional view of the semiconductor position detector shown in FIG.

The semiconductor position detector of the present embodiment is different from the semiconductor position detector of the second embodiment in that its semiconductor conductive layer 1
The semiconductor conductive layer 16 is obtained by changing only the shape of No. 2.

That is, in the present semiconductor position detector, the semiconductor conductive layer 16 has such a shape as to be formed on the entire light receiving surface. Also in the present embodiment, the carriers generated according to the incident light are collected on the semiconductor conductive layer 16 without intervening indirect light collecting means such as a branched conductive layer.

(Sixth Embodiment) FIG. 15 is a plan view of a semiconductor position detector according to a sixth embodiment, FIG. 16 is a cross-sectional view of the semiconductor position detector shown in FIG. 1
FIG. 6 is a sectional view taken along the line BB of the semiconductor position detector shown in FIG. 5.

The semiconductor position detector of the present embodiment is different from the semiconductor position detector of the first embodiment in that its signal extraction electrode 5
The signal extraction electrode 17 is obtained by changing only the shape of the signal extraction electrode 17. The signal extraction electrodes 17 are respectively provided in the outer semiconductor regions 11
At the end in the Y direction. Thus, the chip area of the semiconductor position detector itself can be reduced.

[0046]

As described above, the semiconductor position detector according to the present invention includes the outer semiconductor region having a small resistance value at the end of the semiconductor conductive layer, thereby providing a signal extraction electrode at the end of the semiconductor layer. Missing incident light can be prevented, and detection can be performed with high accuracy without lowering the position resolution.

[Brief description of the drawings]

FIG. 1 is a plan view of a semiconductor position detector according to a first embodiment.

FIG. 2 is a sectional view of the semiconductor position detector shown in FIG.

FIG. 3 is a cross-sectional view of the semiconductor position detector shown in FIG.

FIG. 4 is a plan view of a semiconductor position detector according to a second embodiment.

5 is a cross-sectional view of the semiconductor position detector shown in FIG.

FIG. 6 is a cross-sectional view of the semiconductor position detector shown in FIG.

FIG. 7 is a plan view of a semiconductor position detector according to a third embodiment.

FIG. 8 is a sectional view of the semiconductor position detector shown in FIG.

FIG. 9 is a cross-sectional view of the semiconductor position detector shown in FIG.

FIG. 10 is a plan view of a semiconductor position detector according to a fourth embodiment.

FIG. 11 is a cross-sectional view of the semiconductor position detector shown in FIG.

FIG. 12 is a cross-sectional view of the semiconductor position detector shown in FIG.

FIG. 13 is a plan view of a semiconductor position detector according to a fifth embodiment.

FIG. 14 is a cross-sectional view of the semiconductor position detector shown in FIG.

FIG. 15 is a plan view of a semiconductor position detector according to a sixth embodiment.

16 is a cross-sectional view of the semiconductor position detector shown in FIG.

FIG. 17 is a cross-sectional view of the semiconductor position detector shown in FIG.

FIG. 18 is a plan view of an ordinary semiconductor position detector.

19 is a cross-sectional view of the semiconductor position detector shown in FIG.

20 is a cross-sectional view of the semiconductor position detector shown in FIG.

FIG. 21 is a plan view of the semiconductor position detector when spot light is incident.

22 is an equivalent circuit diagram of the ordinary semiconductor position detector shown in FIG. 21 (FIG. 22A) and an equivalent circuit diagram of the semiconductor position detector according to the embodiment (FIG. 22B).

FIG. 23 is a graph showing the relationship between signal currents I1 and I2 output from the electrode 5 with respect to the incident light spot position X (FIG. 2).
3 (a)) and a graph showing the relationship of the position detection error with respect to the incident light spot position X (FIG. 23 (b)).

[Explanation of symbols]

 2 ... Semiconductor conductive layer, 11 ... Outer semiconductor region.

Claims (1)

[Claims] 1. A semiconductor position detector in which current values output from both ends of a semiconductor conductive layer are variable in accordance with an incident light position in a base line length direction on a light receiving surface, a pair of signals from which the currents are respectively taken out. An extraction electrode, and an outer semiconductor region interposed in a current path between at least one of the both end portions and the signal extraction electrode, wherein the outer semiconductor region is closer to the base line length unit length than the semiconductor conductive layer. Characterized in that the semiconductor position detector is continuously provided on at least one of the both ends so as to have a small resistance value and receive incident light.