JP2001015797A - Semiconductor device for detecting light incidence position and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect incidence position and shape of a line-shaped slip beam with a width by arranging a plurality of one-dimensional regions for detecting light incidence position on the same semiconductor substrate. SOLUTION: An N-type silicon substrate 1 with high resistance is thermally oxidized for forming a silicon oxide film, and an N+ diffusion layer 31 required for separating a P-type diffusion layer 21 for positioning a one-dimensional incidence light position which is arranged in parallel in an array is formed through photoetching and thermal diffusion. Furthermore, a P-type diffusion layer 21' of a high-concentration layer is formed at each two locations of both sides for each P-type diffusion layer 21. Also, the P-type diffusion layer 21 required for detecting a light incidence position is formed through photoetching and ion implantation methods. Then, the reverse side of the N-type silicon substrate is etched, and an N+-type diffusion layer 31 is through thermal diffusion. Finally, an electrode 7 of each diffusion layer is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a semiconductor device for detecting an incident position of light, which can output information on the incident position of light as an electric signal (for example, current).

2. Description of the Related Art A semiconductor device for detecting an incident position outputs information on the position of a point at which light is incident on a detection region of the semiconductor device as a current or the like. This semiconductor device for detecting a light incident position is generally called a PSD (Position Sensit).
A high-resistance silicon semiconductor surface is provided with a resistance layer forming a PN junction, which has a photoelectric effect. When light enters, a photocurrent corresponding to the amount of light and the incident position is provided at both ends of the resistance layer. Is generated to detect the position of the center of gravity of the incident light.

[0003]

2. Description of the Related Art In the case of a conventionally known one-dimensional incident position detecting device, for example, an elongated resistor is formed on a silicon substrate by an impurity diffusion layer of a conductivity type opposite to that of the substrate.
When light enters the resistor, the carrier generated by the light is measured as a current from both electrodes of the resistor and calculated, thereby calculating the light incident point.

[0004] Such a semiconductor device for detecting a light incident position is used as an optical sensor in, for example, a device for determining the shape of an object by irradiating slit light (light cutting line inspection device). Generally, one line, that is, one-dimensional structure is often used. However, a two-dimensional structure in which the detection unit has a rectangular surface has been put to practical use.

FIGS. 6 and 7 show a one-dimensional semiconductor device and a sectional view thereof. Here, FIG. 6 is a top view of the semiconductor device for detecting a one-dimensional light incident position, and FIG. 7 is a sectional view taken along the line AA ′ of FIG. In FIG. 6, a P-type diffusion layer (resistive layer) 2, which is a light incident detection area, is formed as a whole on an N-type silicon substrate 1, and constitutes a PN junction photodiode. At both ends of the P-type diffusion layer (resistive layer) 2, an output part P + -type diffusion layer 2 'of a current generated at the PN junction of the N-type silicon substrate 1 by light incidence and a P-type diffusion layer of an aluminum pattern An electrode 7 is included. The dimensions of the P-type diffusion layer 2 are, for example, a width of 0.1 to 2 mm and a length of 1 to 50 m.
m. As shown in FIG. 7, the N-type silicon substrate 1 also has an N + type diffusion layer electrode 8 for applying a substrate bias voltage.
Are formed. Next, a conventional method for manufacturing such a semiconductor device will be described. A description will be given taking a case of a one-dimensional configuration as an example. The cross-sectional views are shown in FIGS. First, as shown in FIG. 1A, a high resistivity N-type silicon substrate 1 is thermally oxidized to form a silicon oxide film 10 of about 1 μm. Next, as an output portion of a current generated by light incidence, a high-concentration P + -type diffusion layer 2 ′ having a depth of about 1 μm is provided at two ends for the P-type diffusion layer 21 by photoetching and thermal diffusion, for example. Form. This state is shown in FIG.
(B). At this time, the P-type diffusion layer 21 has not been formed yet. Further, a P-type diffusion layer 21 necessary for detecting a light incident position is formed by photoetching and ion implantation so as to connect the two P + -type diffusion layers 2 '. The P-type diffusion layer 2 needs a uniform diffusion layer with high resistance and small concentration variation in order to accurately detect the light incident position. Therefore, ion implantation is used for the formation. See FIG. 8 (c). Subsequently, as shown in FIG. 8D, the entire back surface of the N-type silicon substrate 1 is etched and thermally diffused to form a high-concentration N + -type diffusion layer 3. Finally, a hole for electrode contact of the P + diffusion layer 2 'and the N + diffusion layer 3 on the back surface of the N-type silicon substrate 1 is formed by photoetching, and a thickness of about 0.5 to 1 .mu.m is formed by sputtering or vapor deposition. Is formed, and electrodes 7 and 8 of each diffusion layer are formed by photoetching. As described above, the light incident position detecting semiconductor device is formed as shown in FIG.
Here, the operation principle of the semiconductor device for detecting a light incident position will be briefly described. Light is incident on the junction between one conductive semiconductor substrate (for example, an N-type silicon substrate) and the other conductive semiconductor (for example, a P-type resistor), for example, in a state where the PN junction is reverse-biased. . Then
Carriers are generated by this light and are in a reverse bias state, so that holes flow through the P-type resistive layer and electrons flow through the N-type substrate. Since the P-type resistor has electrodes at both ends, a current flows in inverse proportion to the resistance from the light incident position to each electrode. Assuming that the resistivity distribution of this P-type resistor is uniform,
The resistance value from the light incident position to each electrode is proportional to each distance from the light incident position. Therefore, assuming that currents drawn from the respective electrodes are I1 and I2, I1 / I2 = L2 /
L1. Here, L1 and L2 are distances from the incident position to each electrode. The total length L of the P-type resistor is L
= L1 + L2, and the distance from the incident point of light to the central point of the entire resistor is X, L1 = L / 2 + X, L2 = L /
2-X, whereby X = (L1-L
2) / 2, and from the relational expression of I1 / I2 = L2 / L1, (I1-I2) / (I1 + I2) = (L1
−L2) / (L1 + L2), X = [(L1
+ L2) / 2]. [(I1-I2) / (I1 + I2)]
= L / 2. [(I1-I2) / (I1 + I2)]. In this way, the light incident point can be obtained by measuring the currents drawn from the electrodes at both ends of the P-type resistor of the array-shaped incident position detecting semiconductor device.

[0006]

By the way, it is understood that the conventional position detecting semiconductor device shown here has the following disadvantages. As described above, in this semiconductor device, the position detection is performed only when the incident light is a point-like light beam on the detection area in both the one-dimensional and two-dimensional light incident position detection areas. It is possible. However, when the incident light is in the form of a strip having a width like slit light, for example, a one-dimensional device can detect only the position of the intersection between the light incident position detection area and the slit light. In the conventional two-dimensional position detecting device, there are electrodes for detecting the light spot position at all four corners. The position of the light spot can be specified from the potential of each electrode. However, in the case of slit light, since the light incident point spreads linearly, the incident point is not a point but a line, and position detection that specifies the incident point cannot be performed. An object of the present invention is to make it possible to detect the incident position and the shape even when the incident light is not a point but a line having a width like slit light.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an array of incident position detecting semiconductors in which a plurality of one-dimensional light incident position detecting regions are arranged in parallel on the same semiconductor substrate. The device is formed. Furthermore, the present invention provides a method of manufacturing such a semiconductor device for detecting a light incident position. That is, in the present invention, a plurality of rectangular diffusion regions of the other conductivity type are arranged and formed in parallel on the surface of the semiconductor substrate of one conductivity type, and both ends of the rectangular diffusion region of the other conductivity type are previously provided with the other conductor for electrode extraction. Forming a high-concentration diffusion region, forming an extraction electrode in the other-electrode high-concentration region for taking out the electrode, and forming a substrate bias electrode on the back surface of the one-conductivity-type semiconductor substrate. 6 is a method for manufacturing a semiconductor device for detection.

In the present invention, since a plurality of one-dimensional light incident position detecting regions are arranged in parallel on the same semiconductor substrate, it is possible to detect a point-like incident light in each detecting line region. Therefore, with the present incident position detecting semiconductor device, the connected ones of the above-mentioned point-like incident lights, that is, strip-like slit lights can also be detected on the plurality of parallel detection area incident surfaces.

[0009]

FIG. 1, FIG. 2, FIG. 3, and FIG. 4 show an example of a semiconductor device for detecting an incident position according to the present invention. Further, an embodiment of the manufacturing method will be described with reference to FIGS. FIG. 1 is a top view of an incident position detecting semiconductor device according to the present invention, FIG. 2 is a sectional view taken along line AA 'of FIG.
FIG. 2 is a sectional view taken along line BB ′ of FIG. FIG. 4 is a sectional view showing an embodiment in which a light absorber 99 for absorbing incident light is arranged between P-type diffusion layers 21 arranged in parallel to detect incident light. Hereinafter, in this embodiment, the number of elements is described as three for convenience of drawing. However, in an actual product, the larger the number, the higher the resolution, but at least 10 or more.
About 00 pieces are required.

FIGS. 1 and 2 are different from the conventional example of FIG. 6 in that a plurality of P-type diffusion layers 21 in the light incident detection area are arranged in parallel. Further, an N + -type diffusion layer 31 is formed around each P-type diffusion layer 21 to separate them. Its dimensions are, for example, the P + type diffusion layer 21.
Has a width of 5 to 50 μm, a length of 3 to 25 mm, and an interval of 10 to 100 μm. The N + type diffusion layer 31 has a width of 3 to 20 μm, and the P + type diffusion layer 21 and the N + type diffusion layer 31 have different widths.
Is about 2 to 20 μm.

According to one embodiment of the semiconductor device for detecting an incident position according to the present invention, a bias electrode is provided on the back surface of an N-type semiconductor substrate, and a signal extracting electrode is provided at both ends on the opposite light receiving side. A plurality of rectangular resistance layers are formed side by side by shape diffusion, and each of the resistance layers is formed so as to surround each with a blocking / isolating layer.

Next, the manufacturing method will be described. As shown in FIG. 5 (a), the embodiment of the manufacturing method employs a high resistivity N
The silicon oxide film 10 is formed by thermally oxidizing the shaped silicon substrate 1. The N-type silicon substrate 1 having a resistivity of, for example, 100 to 1000 Ωcm and a thickness of 150 to 300 μm is thermally oxidized to form a silicon oxide film 10 having a thickness of about 1 μm. Next, a P-type diffusion layer 21 for one-dimensional incident light position detection, which is arranged in parallel in an array, is formed by photoetching and thermal diffusion.
First, an N @ + diffusion layer 31 necessary for separating each is formed. Subsequently, as shown in FIG. 5B, the P @ + -type diffusion layer 21 'of the high-concentration diffusion layer is again subjected to photo-etching and thermal diffusion to serve as an output section of the current generated by light incidence.
It is formed at two locations at both ends for the shaped diffusion layer 21. The P @ + -type diffusion layer 21 'of this high concentration diffusion layer has a depth of about 1 .mu.m.
m, are formed at both ends two places 10 ²⁰ to 10 ²¹ cm ³ as high-density of the P + diffusion layer 2 'of the P-type diffusion layer 21.

Further, as shown in FIG. 5C, the respective P-type diffusion layers 21 necessary for detecting the light incident position are formed by photoetching and ion implantation. This P-type diffusion layer 21
Is about 0.5 μm and 10 ¹⁷ , for example.
It is about 10 ¹⁸ cm ³ . However, the isolation N + type diffusion layer 31, the P + type diffusion layer 21 'and the P type diffusion layer 21 have a pattern shape which does not contact as shown in FIG. Subsequently, as shown in FIG. 5D, the back surface of the N-type silicon substrate 1 is etched, and the N + -type diffusion layer 3 is formed by thermal diffusion. This N + type diffusion layer 3 has a concentration of, for example, about 1 μm in depth and about 10 ²² cm ³ .

Finally, as shown in FIG. 5E, contact holes are formed in the P + type diffusion layer 21 'and the N + type diffusion layer 3 on the back surface of the N type silicon substrate 1 by photoetching, and sputtering or vapor deposition is performed. Forming an aluminum film by the method of
The electrodes 7 and 8 of each diffusion layer are formed by photoetching.

Thereafter, as shown in FIG. 4, a light absorber 99 formed in a slit shape, for example, graphite or the like is provided by sputtering or photoetching, and a region other than the P-type diffusion layer 21 is shielded from light to form a P-type diffusion layer. Interference between regions of the shaped diffusion layer 21 as photodiodes can be further reduced. In addition, by appropriately changing the width of the light absorber 99 serving as the slit, the amount of detection current output from each photodiode on the applicable semiconductor device for detecting the incident position can be changed. Thus, the light incident position detecting semiconductor device according to the present invention is formed as shown in FIG.

In this way, by measuring the currents taken out from the electrodes at both ends of the P-type resistor of the semiconductor device for detecting the incident position in a plurality of arrays arranged in parallel,
It is possible to obtain the incident pattern of the band-like light. The operations from current measurement to position detection are as described above. Such a semiconductor device for detecting a light incident position according to the present invention can be used, for example, as an image pickup device of a light cutting line extracting circuit disclosed in Japanese Patent Application Laid-Open No. 63-132107.

[0017]

As described above, according to the present invention,
Since a plurality of one-dimensional light incident position detection areas are arranged in parallel on the same semiconductor substrate, point-like incident light can be detected in each detection area. Accordingly, the present incident position detecting semiconductor device can also detect the position and shape of linear light, that is, a strip of light that connects points. As described above, according to the semiconductor device for detecting a light incident position according to the present invention, the pattern of the slit light is not required to be extracted and extracted from the image obtained by the ordinary television camera, and the pattern of the slit light is directly changed. If used as a sensor of an inspection device, the inspection speed can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

FIG. 2 is a sectional view of an embodiment of the present invention.

FIG. 3 is a sectional view of an embodiment of the present invention.

FIG. 4 is a sectional view of an embodiment of the present invention.

FIG. 5 is a sectional view showing a manufacturing process according to the embodiment of the present invention.

FIG. 6 is a plan view of a conventional example.

FIG. 7 is a sectional view of a conventional example.

FIG. 8 is a cross-sectional view showing a manufacturing process of an example of a conventional example.

[Explanation of symbols]

1: N-type silicon substrate, 10: silicon oxide film, 2, 2
1: P-type diffusion layer, 2 ', 21': P + -type diffusion layer, 3,
3 ', 31: N + type diffusion layer, 7, 71: P + diffusion layer electrode,
8: N + diffusion layer electrode (backside of N-type silicon substrate).

Claims (6)

[Claims] 1. A light incident position detecting semiconductor device for detecting a position of a light receiving point and outputting the position as an electric signal, comprising: a semiconductor substrate of one conductivity type; A rectangular diffusion region of the other conductivity type disposed and formed; a high concentration diffusion region of the other conductivity type for taking out electrodes formed at both ends of the plurality of rectangular diffusion regions of the other conductivity type; Signal extraction electrode,
A semiconductor device for detecting a light incident position, comprising a substrate bias electrode formed on a back surface of the one conductivity type semiconductor substrate. 2. The incident position detecting semiconductor device according to claim 1, wherein each of the plurality of rectangular diffusion regions has a separation region around the diffusion region for separating the diffusion region. 3. The incident position detecting semiconductor device according to claim 1, wherein a light-shielding mask is formed on a light-receiving surface other than the plurality of rectangular diffusion regions arranged in parallel. 4. A method of manufacturing a light incident position detecting semiconductor device for detecting a position of a light receiving point and outputting the position as an electric signal, wherein a rectangular diffused region of the other conductive type is formed on the surface of one conductive type semiconductor substrate. A plurality of the other conductive type high-concentration diffusion regions are formed in advance at both ends of the plurality of rectangular diffusion regions of the other conductive type, and then the other conductive type of the other conductive type is formed. A method of manufacturing a semiconductor device for detecting an incident position, wherein an electrode for extracting an output signal is formed in a high-concentration region, and a substrate bias electrode is formed on a back surface of the one conductivity type semiconductor substrate. 5. A method for manufacturing a light incident position detecting semiconductor device for detecting a position of a light receiving point and outputting the position as an electric signal, wherein a plurality of rectangular shapes formed on a conductive semiconductor substrate in a next step are formed. A diffusion region for separating the respective diffusion regions is formed around the rectangular diffusion region, and a plurality of the other conductivity type rectangular diffusion regions are formed in parallel on the surface of the one conductivity type semiconductor substrate. A high-concentration diffusion region for extracting an output signal is formed in advance at both ends of the plurality of rectangular diffusion regions of the other conductivity type. A method for manufacturing a semiconductor device for detecting an incident position, wherein an electrode for extracting an output signal is formed in a concentration region, and a substrate bias electrode is formed on a back surface of the one conductivity type semiconductor substrate. 6. The method for manufacturing a semiconductor device for detecting a light incident position according to claim 4 or 5, wherein a light-shielding mask for shielding light other than light-receiving portions of the plurality of rectangular diffusion regions arranged in parallel is formed. A method for manufacturing a semiconductor device for detecting an incident position, comprising: