JPH0543365Y2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> This invention relates to a semiconductor position detection device, and particularly to a device using an integrated light receiving element.

<<Prior Art>> Conventionally, a semiconductor optical position detection device using an integrated light receiving element has been proposed in Japanese Patent Application No. 159561/1982.

A sectional view showing the element structure of the previously proposed semiconductor optical position detection device is shown in FIG. 4, and a planar layout thereof is shown in FIG. That is, the epitaxial substrate 1 is constructed by forming a high resistivity n-type epitaxial layer 3 on a p-type silicon substrate 2, and the island-like regions 3 of the n-type epitaxial layer 3 are formed on a p-type silicon substrate 2.
a and 3b are surrounded by a P ⁺ isolation diffusion region 4.
Further, an n ⁺ buried layer 5 is provided in a part between the P-type silicon substrate 2 and the n-type epitaxial layer 3 .
P-type base diffusion regions 6, 6a, 7, and 7a are provided in parallel to two opposing sides of the island regions 3a and 3b of the n-type epitaxial layer, respectively, and an n ⁺ diffusion region 8 is further provided to surround them. It is being

Furthermore, between the P-type regions 6 and 7 and between 6a and 7a,
In between is a P-type resistance layer 9 formed by boron ion implantation.
and 9a are formed. That is, the above P
The resistive layers 9 and 9a form p-n junctions with island-shaped n-type semiconductor regions 3a and 3b separated by a p ⁺ isolation diffusion region, and two P-type regions for electrodes are formed on two opposing sides thereof. Therefore, when this region is irradiated with light, a photocurrent corresponding to the irradiation position of the light is generated from the two P-type regions 6, 7 or 6a, 7a. Therefore, the P-type resistance layers 9 and 9a form detection elements (hereinafter referred to as "PSD") a and b that detect the optical position.

In the figure, 10, 10a, 11, and 11a are output metal electrodes, 12 is a bias metal electrode, and 13 is a metal electrode for output.
The SiO ₂ film and 14 are contact holes,
Further, a light-shielding film 15 made of metal is formed on the upper surface of the PSDb to serve as a dummy PSD, and therefore, this PSDb forms a light-shielded region of the opposite conductivity type.

The semiconductor position detection device described above is formed into a single chip by a normal bipolar process.

Now, in the semiconductor optical position detection device described above, in order to detect the optical position, when the optical spot is located on PSDa, a photocurrent is generated, and the output currents ₁ and 2 from the two P-type regions 6 _{and 7} are connected to the operational amplifiers 20 and 20. 21 and feedback resistors 22 and 23, it is converted into a voltage and detected.

On the other hand, since the dummy PSDb is shielded from light by the light-shielding film 15, a leakage current occurs at a high temperature at which no photocurrent is generated. This leakage current is turned back by the current mirror circuits 24 and 25 and used for detection.
The leakage current can be canceled by subtracting it from the PSDa output signal.

<<Problems to be solved by the invention>> However, in the case of the above-mentioned semiconductor optical position detection device, the size of the PSD is very large, for example, 4.
~30mm x 1~5mm, and the detection PSDa and the dummy PSDb for leakage current compensation were formed separately, so the detection PSDa and the dummy PSDb were formed separately.
There was a problem in that the leakage current of PSDb did not become the same due to local non-uniformity of process parameters such as fractional carrier life and impurity concentration, making it impossible to adequately compensate for leakage current.

<<Purpose of the invention>> The present invention was made to solve the above-mentioned conventional problems, and aims to provide a semiconductor optical position detection device that can reliably compensate for leakage current.

<Means for Solving the Problems> In order to achieve the above object, the present invention forms a semiconductor region of one conductivity type with an opposite conductivity type region where light is irradiated and an opposite conductivity type region where light is blocked. , in a semiconductor optical position detection device that detects a light position by subtracting an output signal of an opposite conductivity type region from which light is shielded from an output signal of an opposite conductivity type region from which light is irradiated to compensate for leakage current; The device is characterized in that a plurality of regions of opposite conductivity type that are irradiated with light and regions of opposite conductivity type that are shielded from light are arranged alternately, and the respective regions are connected in parallel.

《Operation》 The present invention uses a light-shielded PSD and an unshielded PSD.
PSDs are arranged alternately and connected in parallel to act to cancel leakage current.

<<Example>> Hereinafter, the present invention will be explained based on the drawings. Note that the same reference numerals are given to the same components as in the prior art for explanation.

FIG. 1 shows a first embodiment of a semiconductor optical position detection device according to the present invention, and shows its planar layout. As is clear from this figure, a plurality (in this example, five) of detection PSDa ₁ to a ₅ and a plurality of dummy PSDs b ₁ to b 5 are arranged alternately in front and back in the island region made of the n-type epitaxial layer ₃ . It has a well-placed structure. In other words, P on the left and right sides respectively.
shaped base diffusion regions 6, 6... 6a, 6a... and 7, 7..., 7a, 7a... are provided, and P-type resistance layers 9, 9... formed by boron ion implantation are provided between these regions. ...and 9a, 9a... are formed. In the figure, 4 is a p ⁺ isolation diffusion region provided surrounding the n-type epitaxial layer 3, and 8 is an n-type epitaxial layer 3.
The n ⁺ diffusion region provided around the epitaxial layer 3 and 14 are contact holes provided in the SiO ₂ film (not shown). In addition, a light shielding film 1 made of metal is placed on the surface of the dummy PSDs b ₁ to _{b 5} .
5 is formed.

Detection PSDa ₁ ~ arranged alternately as described above
In a ₅ and dummy PSDs _{b 1} to _{b 5} , the output signals are taken out by metal electrodes 10, 11 and 10a, 11a connected in parallel to each group, and the n ⁺ diffusion region 8 is taken out by a bias electrode 12. Voltage is now applied.

As described above, the planar layout of this embodiment has a relationship in which the conventional planar layout of FIG. 5 described above is alternately arranged vertically. Therefore,
The cross-sectional shape of this embodiment is the same as that shown in FIG. 4 described above, so it is omitted. Further, since the basic operation of optical position detection is the same, the explanation of the operation will be omitted since it will be redundant.

By the way, in this embodiment, as described above,
Since PSDa ₁ to a ₅ and dummy PSDs _{b 1} to b ₅ are arranged alternately, photocurrent is generated alternately in each detection PSDa ₁ to a ₅ , and leakage due to high temperature occurs in each dummy PSD b ₁ to b _5. A current is generated. Since these currents are connected in parallel for each group, the respective photocurrents become an output signal that is added together, and the leakage current also becomes an output signal that is added together. Further, the leak current is canceled by subtracting the added leak current from the added photo current by a current mirror circuit (not shown).

As mentioned above, in this embodiment, even if the process parameters are uneven within the chip,
Since the detection PSD and dummy PSD are arranged evenly and alternately, the detection PSDa ₁ ~
The leak currents from a ₅ and the dummy PSDs b ₁ to b ₅ can be made almost equal, and sufficient leak current compensation can be achieved. That is, at least PSDa,
It is sufficient that the irradiation light is applied to one or more sets of PSDb. Therefore, optical position detection can be performed with high accuracy even at high temperatures.

In addition, the total area of each PSD is the area of the conventional PSD, so the chip size is the same as the conventional one.
Furthermore, it can be manufactured without increasing the number of process steps.

Furthermore, since it is manufactured using a bipolar process, it has the advantage that peripheral circuits can also be integrated.

2 and 3 show a second embodiment of the present invention, FIG. 2 is a plan layout diagram thereof, and FIG.
The figure shows a sectional view taken along the line A--A in FIG. 2.

In this embodiment, six PSDs are formed by replacing the P-type resistance layers 9, 9a of the first embodiment shown in FIG. PSDa ₁ to a ₃ for detection and dummy
PSDb ₁ to b ₃ .

Here, the P-type silicon substrate 2 is grounded and a positive voltage is applied to the n ⁺ diffusion region 8 to operate the PSD.

Also in this embodiment, since the detection PSDa ₁ to a ₃ and the dummy PSDb ₁ to b ₃ are arranged alternately, the same effect as in the first embodiment described above can be obtained.

<Effects> As described above, according to the present invention, multiple PSDs are installed in parallel, and their outputs are connected in parallel to every other one, and the output of one of the groups connected in parallel is
Since the PSD is configured to be used as a dummy PSD by forming a light-shielding film on a flat surface, it can be used for detection even if process parameters are uneven locally within the chip.
The leakage currents of the PSD and the dummy PSD at high temperatures are approximately equal, and leakage current compensation can be performed reliably.

This has the effect of allowing highly accurate optical position detection even at high temperatures.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a first embodiment of a semiconductor optical position detection device according to the present invention, and FIGS. 2 and 3 show a second embodiment of the present invention. 3 is a sectional view taken along the line A-A in FIG. 2, and FIGS. 4 and 5 show a conventional semiconductor optical position detection device. FIG. 4 is a plan view thereof, and FIG. FIG. 2 is a cross-sectional view showing the element configuration of a conventional semiconductor optical position detection device. 1...Epitaxial substrate, 2...P type silicon substrate, 3...N type epitaxial layer, 4...
P ⁺ separation diffusion region, 5...n ⁺ buried layer, 6,6
a, 7, 7a...P-type base diffusion region, 8...
n ⁺ emitter region, 9, 9a...P type resistance layer (opposite conductivity type region), 10, 10a, 11, 11a...
... Metal electrode for output, 12 ... Metal electrode for bias, 13 ... SiO ₂ film, 14 ... Contact hole, 15 ... Light shielding film, PSDa ₁ to a ₅ ... Detection element for detection, PSDb ₁ to b ₅ ...Detection element for dummy.

Claims (1)

[Claims for Utility Model Registration] One conductivity type semiconductor region is formed with an opposite conductivity type region to which light is irradiated and an opposite conductivity type region to which light is blocked, and the output of the opposite conductivity type region to which the light is irradiated. In a semiconductor optical position detection device that detects a light position by subtracting an output signal of an opposite conductivity type region where light is shielded from a signal and compensating for leakage current, A semiconductor optical position detection device characterized in that a plurality of conductive regions are arranged alternately and each region is connected in parallel.