JPH0766448A - Photo diode for positional detection and its manufacture - Google Patents

Abstract

PURPOSE:To provide a manufacturing method for a photo diode for positional detection which can be manufactured at low cost and which has high-level characteristics with little leakage current. CONSTITUTION:A semiconductor substrate 1 includes on its surface a p type resistance layer formed in a preset pattern and an N type channel stopper layer 5 formed in a pattern surrounding the pattern of the resistance layer 4. The pattern of the resistance layer 4 matches the internal perimeter of the pattern of the channel stopper layer 5. An insulating film of a preset thickness is formed on the surface of the semiconductor substrate, and lithography is applied to open a pattern for the channel stopper layer 5 on the insulating film. An N type impurty is introduced with the insulating film as a mask to form the channel stopper 5. Ion implantation of a P type impurity is made to the surface of the semiconductor by establishing an acceleration energy, which will penetrate the insulating film but which will ensure an implanting depth not to exceed the depth of the channel stopper layer, and the resistant layer 4 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting photodiode. More specifically, the present invention relates to a photodiode provided with a resistive layer having a predetermined pattern on the surface of a semiconductor substrate to detect the position of light incident on the substrate surface.

[0002]

2. Description of the Related Art As a conventional position detecting photodiode, there is one as shown in FIG. 2 (FIG. 2 (a) shows a pattern layout and FIG. 2 (b) shows B- in FIG.
The cross section along line B'is shown. ). As shown in FIG.
In this position detecting photodiode, a resistance layer (P-type diffusion layer) 104 having a zigzag pattern is formed on the surface of an N-type silicon substrate 101, and a channel stopper layer (N ⁺ which surrounds the resistance layer 104 with a gap δ therebetween. Mold diffusion layer) 105. Electrodes 102 and 103 are provided on both ends of the resistance layer 104.
The channel stopper layer 105 is in contact with the cathode electrode 108 at the corner of the substrate surface.
In addition, as shown in FIG. 3B, SiO _{2 is} formed on almost the entire surface of the substrate.
The film 107 is provided, and the N ⁺ type diffusion layer 10 is formed on the entire back surface of the substrate.
6 is provided.

This position detecting photodiode is manufactured as follows. First, the N-type silicon substrate 10
A SiO ₂ film is formed on each of the front surface and the back surface of 1. First
The second photolithography is performed, and SiO 2 on the substrate surface is
_A pattern for the channel stopper layer 105 is opened in the _two films. Thermal diffusion of N ⁺ type impurities is performed to form a channel stopper layer (N ⁺ type diffusion layer) 105 on the front surface of the substrate and an N ⁺ type diffusion layer 106 on the back surface of the substrate. Drive oxidation is performed to form a silicon oxide film on the surface of the channel stopper layer 105. Next, the second photolithography is performed to form the resistance layer 10 on the SiO ₂ film on the substrate surface.
Open the pattern for 4. Using this SiO ₂ film as a mask, P ⁺ -type impurities are ion-implanted to form the resistance layer 104 on the substrate surface. Finally, the electrodes 102 and 103 are formed on both ends of the resistance layer 104, and the cathode electrode 108 is formed on the corner portion.

[0004]

By the way, the photodiode as described above is required to be manufactured at low cost and to have good characteristics.

However, in the above conventional position detecting photodiode, the resistance layer 104 and the channel stopper layer 1 are used.
Photolithography is performed twice to form No. 05. Therefore, there is a problem that the price becomes high.

Further, since the N-type semiconductor substrate is exposed on the element surface through the gap δ between the resistance layer 104 and the channel stopper layer 105, there is a problem that surface recombination increases and leakage current increases.

Therefore, an object of the present invention is to provide a high-performance photodiode for position detection which can be manufactured at a low cost and has a small leak current, and a manufacturing method thereof.

[0008]

In order to achieve the above object, the position detecting photodiode according to claim 1 is provided with:
On the surface of the semiconductor substrate, a resistance layer of one conductivity type of P-type or N-type formed in a predetermined pattern and the other of the P-type or N-type formed in a pattern surrounding the pattern of the resistance layer. In the position detecting photodiode having a channel stopper layer having a conductivity type, the pattern of the resistance layer is matched with the inner circumference of the pattern of the channel stopper layer.

A method of manufacturing a position detecting photodiode according to a second aspect of the present invention is a method of manufacturing the position detecting photodiode according to the first aspect of the present invention, wherein A step of forming an insulating film having a predetermined thickness on the surface; a step of performing photolithography to open a pattern for the channel stopper layer in the insulating film; and a step of using the insulating film as a mask for the other conductivity type A step of introducing an impurity to form the channel stopper layer on the substrate surface, the one conductivity type impurity on the substrate surface, penetrating the insulating film, and
And a step of forming a resistance layer in contact with the inner circumference of the pattern of the channel stopper layer by ion-implanting with an implantation depth set to an acceleration energy not exceeding the depth of the channel stopper layer. Manufacturing method of photodiode for position detection.

[0010]

In the position detecting photodiode according to the present invention, the pattern of the resistance layer coincides with the inner circumference of the pattern of the channel stopper layer, so that there is a gap between the resistance layer and the channel stopper layer. Absent. That is, the N-type semiconductor substrate is not exposed on the element surface. Therefore, the surface recombination is reduced, the leakage current is reduced, and the characteristics are improved as compared with the conventional case. Further, the resistance layer and the channel stopper layer are formed with the same mask, and as a result, the number of times of photolithography is reduced, and it is possible to manufacture at a low cost.

According to the manufacturing method of the position detecting photodiode of the second aspect, in the position detecting photodiode of the first aspect, the resistance layer and the channel stopper layer are formed by one-time photolithography. It Therefore,
A position detecting photodiode can be manufactured at a lower price than ever before.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The position detecting photodiode of the present invention will be described in detail below with reference to embodiments.

FIG. 1 shows a position detecting photodiode according to an embodiment. The figure (a) shows the pattern layout, and the figure (b) shows the BB 'line cross section in the figure (a).

As shown in FIG. 1A, this position detecting photodiode has a resistance layer (P-type diffusion layer) 4 having a zigzag pattern and a resistance layer 4 on the surface of an N-type silicon substrate 1. A surrounding channel stopper layer (N ⁺ type diffusion layer) 5 is provided. The pattern of the resistance layer 4 matches the inner circumference of the pattern of the channel stopper layer 5, and electrodes 2 and 3 are provided at both ends of the resistance layer 4. The channel stopper layer 5 is at a floating potential. Cathode electrodes 8 are provided on the corners of the substrate surface. As shown in FIG.
An N ⁺ type contact layer 5 ′ is provided around the element in a state of being separated from the channel stopper layer 5 (this N ⁺ type contact layer 5 ′ is electrically connected to the cathode electrode 8). . Further, the SiO ₂ film 7 is provided on almost the entire front surface of the substrate, and the N ⁺ type diffusion layer 6 is provided on the entire rear surface of the substrate.

The position detecting photodiode is manufactured as follows.

First, N having a specific resistance of about 1000 Ω-cm
The type silicon substrate 1 is oxidized to form a 1500 Å thick SiO ₂ film as an insulating film on the front and back surfaces thereof, respectively.

Next, photolithography is performed to open a pattern for the channel stopper layer 5 in the SiO ₂ film on the surface of the substrate. At this time, the SiO ₂ film on the back surface of the substrate is entirely removed.

Next, phosphorus is thermally diffused as an N ⁺ type impurity to form a channel stopper layer (N ⁺ type diffusion layer) on the substrate surface.
5 and an N ⁺ type contact layer 5 ′ are formed,
An N ⁺ type diffusion layer 6 is formed on the back surface of the substrate. The layers 5, 5'and 6 may be formed by ion implantation.

Next, boron is ion-implanted as P ⁺ -type impurities on the entire surface of the substrate. At this time, the acceleration energy of implantation is set to a value such that boron penetrates the SiO ₂ film on the substrate surface and the implantation depth does not exceed the depth of the channel stopper layer 5. As a result, the resistance layer 4 is formed in contact with the inner circumference of the pattern of the channel stopper layer 5.

Next, phosphorus treatment and annealing are performed to stabilize the device surface.

Finally, Al vapor deposition is performed to form the electrode 2,
3 and 8 are formed.

In this position detecting photodiode, since the pattern of the resistance layer 4 coincides with the inner circumference of the pattern of the channel stopper layer 5, there is no gap between the resistance layer 4 and the channel stopper layer 5, and the element The N-type silicon substrate is not exposed on the surface. Therefore, it is possible to reduce surface recombination, reduce leakage current, and improve the characteristics, as compared with the related art.

Further, the resistance layer and the channel stopper layer can be formed with the same mask, and as a result, the number of times of photolithography can be reduced. Therefore, it can be manufactured at a lower cost than conventional ones.

Since the channel stopper layer 5 inside the element and the N ⁺ type contact layer around the element (which is electrically connected to the cathode electrode 8) are separated from each other, the electrostatic breakdown voltage does not decrease.

[0025]

As is apparent from the above, in the position detecting photodiode according to the first aspect, since the pattern of the resistance layer matches the inner circumference of the pattern of the channel stopper layer, the resistance layer and the channel stopper. There is no gap between the layers and the N-type semiconductor substrate is not exposed on the element surface. Therefore, it is possible to reduce surface recombination, reduce leakage current, and improve the characteristics, as compared with the related art. Also,
The resistance layer and the channel stopper layer are formed with the same mask, and as a result, the number of times of photolithography is reduced, and it is possible to manufacture at a low cost.

According to the method of manufacturing the position detecting photodiode of the second aspect, the resistance layer and the channel stopper layer of the position detecting photodiode of the first aspect are formed as one layer.
It can be formed by one time photolithography. Therefore, the position detecting photodiode can be manufactured at a lower cost than ever before.

[Brief description of drawings]

FIG. 1 is a diagram showing a pattern layout and a sectional structure of a position detecting photodiode according to an embodiment of the present invention.

FIG. 2 is a diagram showing a pattern layout and a sectional structure of a conventional position detecting photodiode.

[Description of Reference Signs] 1 N-type silicon substrate 2, 3, 8 electrode 4 P ⁺ type resistance layer 5 N ⁺ type channel stopper layer 5 ′ N ⁺ type contact layer 6 N ⁺ type diffusion layer 7 SiO ₂ film

Claims (2)

[Claims] 1. A resistance layer of one conductivity type of P type and N type formed in a predetermined pattern on a surface of a semiconductor substrate, and P type or N formed in a pattern surrounding the pattern of the resistance layer. In a position detecting photodiode having a channel stopper layer having the other conductivity type among the above types, the pattern of the resistance layer matches the inner circumference of the pattern of the channel stopper layer. Photodiode. 2. A method for manufacturing a position detecting photodiode according to claim 1, comprising a step of forming an insulating film having a predetermined thickness on a surface of a semiconductor substrate. Forming the channel stopper layer on the surface of the substrate by performing lithography to open a pattern for the channel stopper layer in the insulating film, and introducing the other conductivity type impurity using the insulating film as a mask. And the ion implantation of the impurity of one conductivity type into the surface of the substrate by accelerating energy so as to penetrate the insulating film and not exceed the depth of the channel stopper layer. A method for manufacturing a photodiode for position detection, comprising the step of forming a resistance layer in contact with the inner circumference of the pattern of the channel stopper layer.