JPS62179774A - Manufacture of image sensor - Google Patents

Abstract

PURPOSE:To simplify a manufacturing process by forming two projections on an element forming region on a substrate, forming electrodes thereon, and then sequentially growing one conductivity type semiconductor layer and an intrinsic semiconductor layer on the entire substrate over the electrodes. CONSTITUTION:The entire glass substrate 1 is covered with an SnO2 layer, patterned to form electrodes 2A, 2B, with the electrodes as masks two projections 1A, 1B are formed by dry etching on an element forming region. Then, a p-type a-Si layer 3 is formed as one conductivity type semiconductor layer and an i-type a-Si layer 4 is formed as an intrinsic semiconductor layer continuously by a plasma CVD method, and the entire substrate is covered as a protective film with an an Si3N4 layer 5. The photodetector formed in this manner is formed by burying a pair of electrodes between the substrate and an element and of the type for receiving light from the back surface of the substrate. In this case, it is a planar type that the element surface is buried. Lithographic steps are reduced to simplify the manufacturing process.

Description

[Detailed Description of the Invention] [Summary] A method of forming a light-receiving element with electrodes formed on one side in a back-side cell structure (a structure that receives light from the back side of a substrate) is proposed to simplify the manufacturing process of an image sensor.

[Industrial application field]

The present invention relates to a method for manufacturing a planar image sensor having a back cell structure.

Amorphous silicon (hereinafter abbreviated as a-3i) has been put into practical use in various devices in recent years because it is cheaper and easier to mass produce than conventional single crystal silicon.

In particular, light receiving elements using a-5t are used in solar cells, facsimile image sensors, and the like.

As image sensor systems become larger and more sophisticated, there is a demand for improved characteristics and higher conversion rates of the cell arrays that make up the systems.

[Conventional technology]

FIGS. 2(1) to 2(4) are cross-sectional views illustrating the manufacturing process of a conventional image sensor.

In Fig. 2 (1), 21 is a substrate, which is a glass substrate or a ceramic substrate, and a film is formed thereon by the usual vapor phase epitaxy (CVD) method, and then patterned using ordinary lithography to form the element. A silicon nitride (SiJ<) layer 22 is formed over the region.

In Figure 2 (2), an i-type (
Intrinsic) The a-3i layer 23 and the p-type a-3i layer 24 are successively grown.

Next, by patterning using dry etching using CF, +O□ as a reactive gas, the p-type a-3i layer 24 and the i-type a-8
The i-layer 23 is removed.

In FIG. 2(3), the p-type a-3i layer 24 is patterned and separated into a p-type a-3i layer 24A and a p-type a-3i layer 24A.
Form layer 24B.

In FIG. 2 (4), the p-type a-5i layer 24A and the p-type a
-5i layer 24B'', electrodes (transparent electrodes) 25A and 25B each consisting of a 5n02 layer are formed.

The light-receiving element formed as described above has a pair of electrodes on the substrate surface and receives light from the substrate surface, but in this case, since the element surface is exposed, the element performance may be affected. , or it is disadvantageous in terms of reliability.

In response, the present inventors have considered making the device planar in order to improve the photocurrent and temperature characteristics.

[Problem that the invention seeks to solve]

If planarization is performed with a back cell structure according to the conventional manufacturing process, the p-type a-3i layer 24 cannot be separated, resulting in a short circuit between the electrodes, which prevents device formation. It was impossible.

[Means for solving problems]

To solve the above problem, in the element formation region on the substrate (11),
A step of forming two convex portions (1A, 1B), and a step of forming the two convex portions (1A, 1B).
forming electrodes (2A, 2B) on the substrate (1A, 1B), and covering the electrodes (2A, 2B) on the entire surface of the substrate (1);
This is achieved by the method for manufacturing a planar image sensor according to the present invention, which includes the steps of sequentially growing a semiconductor layer (3) of one conductivity type and an intrinsic semiconductor layer (4).

[Effect]

In the present invention, an electrode and a p-type a-3i layer are separated by a step of a convex portion formed on a substrate, and an i-type a-5i layer is grown on the entire surface of the substrate, thereby creating a back cell structure. This allows for the formation of planarized elements.

〔Example〕

FIGS. 1 (11 to 4) are cross-sectional views illustrating the manufacturing process of an image sensor according to the present invention.

In Figure 1 ill, 1 is a substrate, using a glass substrate,
A 5n02 layer with a thickness of 1000 layers is deposited on the entire surface and patterned to form electrodes 2^, 2B.

In FIG. 1 (2), using the electrodes 2A and 2B as a mask, dry etching is performed using CF or CCI□pz+oz as a reactive gas to form a layer with a height of 20 mm in the element formation area.
Two protrusions 1A and 1B with a thickness of 0 Å or more are formed.

In FIG. 1 (3), a p-type a-3i layer 3 with a thickness of 200 nm as a one conductivity type semiconductor layer and an i-type a-
3i layer 4 is grown continuously.

In FIG. 1(4), a Si3N4 layer 5 with a thickness of 50 Å or more is deposited as a protective film over the entire surface of the substrate.

The light-receiving element formed as described above has a pair of electrodes embedded between the substrate and the element and is of a type that receives light from the back surface of the substrate, and in this case is a planar type in which the surface of the element is embedded.

Furthermore, the number of lithography steps is reduced compared to the conventional example, and the manufacturing process can be simplified.

〔Effect of the invention〕

As described above in detail, the manufacturing process of the present invention allows the light receiving element to have a back cell structure and is planarized, thereby simplifying the manufacturing process of the image sensor.

[Brief explanation of drawings]

Figures 1 (1) to (4) are cross-sectional views explaining the manufacturing process of an image sensor according to the present invention, and Figures 2 (1) to (4) are cross-sectional views explaining the manufacturing process of an image sensor according to a conventional example. be. In the figure, 1 is a substrate, which is a glass substrate, 2A and 2B are electrodes, which are 5N02 layers, 3 is a single conductivity type semiconductor layer, which is a p-type A-3A layer, 4 is an intrinsic semiconductor layer, which is an I-type A-5A layer, and 5 is a protection layer. 1 Figure 1 ＼ -X <AC'co

Claims (1)

[Claims] Two convex portions (1A, 1
A step of forming electrodes (2A, 2B) on the convex portions (1A, 1B); A method for manufacturing an image sensor, comprising the steps of sequentially growing a type semiconductor layer (3) and an intrinsic semiconductor layer (4).