Solid-state image pickup device

Abstract

A solid-state image pickup device is provided which includes a substrate; a transistor formed on the substrate; a photoelectric conversion element including a first electrode connected to a drain or a source of the transistor, a semiconductor layer stacked on the first electrode, and a second electrode stacked on the semiconductor layer; an insulating layer disposed on the second electrode; and a bias line formed on the insulating layer to be connected to the second electrode, in which the insulating layer contains at least an inorganic insulating film, and the bias line is connected to the second electrode via a contact hole formed in the insulating layer, and a side surface of the semiconductor layer is in contact with the inorganic insulating film.

Description

CROSS REFERENCES TO RELATED APPLICATIONS[0001]The entire disclosure of Japanese Patent Application Nos. 2008-112113, filed Apr. 23, 2008 and 2008-319271, filed Dec. 16, 2008 are expressly incorporated by reference herein.BACKGROUND[0002]1. Technical Field[0003]The present invention relates to a solid-state image pickup device for converting incident light into electrical signals and to a manufacturing method thereof.[0004]2. Related Art[0005]In medical image diagnosis or non-destructive inspection, imaging is performed using radioactive rays such as X rays. However, since a reduction optical system is difficult to implement in imaging of the radioactive rays, the imaging is necessarily performed at the same magnification. Therefore, the medical image diagnosis or the non-destructive inspection requires a large imaging surface, and thus, a solid-state image pickup device having a variety of type of thin films deposited on a glass substrate or the like so that a plurality of pixels is...

AI Technical Summary

Benefits of technology

[0011]An advantage of some aspects of the invention is that it provides a solid-state image pickup device and a manufacturing method thereof capable of providing reliable electrical connection between a photoelectric conversion element and a bias line and electrically connecting the photoelectric conversion element and a field-effect transistor with fewer contact holes.

[0015]The insulating layer formed on the second electrode contains an inorganic insulating film formed, for example, of a silicon nitride film, which is an inorganic film. Moreover, the inorganic insulating film is formed to be in contact with the second electrode, preferably with the side surface of the semiconductor layer so as to cover them. In the solid-state image pickup device having such a configuration, the side surface of the semiconductor layer is disposed to be in contact with the inorganic film, and preferably, the semiconductor layer and the second electrode are covered with the inorganic film. Owing to such a configuration, the semiconductor layer and the second electrode are protected by the inorganic film from coming into contact with moisture or air during or after the manufacturing process such as the process for forming the bias line. Therefore, the photoelectric conversion element is not likely to deteriorate, and thus, the reliability of the solid-state image pickup device can be increased.

[0017]According to the solid-state image pickup device of the invention, since the contact hole can be formed by etching the inorganic insulating film using a photolithography technique, for example, in a state where a resist mask is formed thereon, it is possible to reliably form the contact hole at a position where it overlaps with the second electrode. Therefore, it is possible to reliably prevent a situation where the insulating film is unintendedly left on the second electrode, and thus, the electrical connection between the second electrode and the bias line can be carried out in a reliable manner. Furthermore, by forming the top protection layer on the insulating layer so as to cover the bias line, it is possible to prevent the bias line from eroding or deteriorating. The top protection layer is preferably formed of an inorganic film such as a silicon nitride film.

[0019]According to the configuration, the first electrode is electrically connected to, for example, a drain of the transistor by at least a portion thereof overlapping with the upper surface of the drain. In such a case, the lower insulating film may be formed to be disposed between the drain and the first electrode so that the first electrode overlaps with the upper surface of the drain within a contact hole formed in the lower insulating film. According to the configuration, since it is not necessary to form a contact hole in the insulating layer on the second electrode, for electrically connecting the photoelectric conversion element and the transistor to each other, the photoelectric conversion element can be formed in a larger region, and the sensitivity of the photoelectric conversion element can be increased.

[0021]In the configuration, the lower insulating film is formed so as to cover the transistor. Owing to such a configuration, the transistor, particularly, a channel region thereof is protected by the lower insulating film from being damaged by an etching process or the like when forming the photoelectric conversion element. An inorganic insulating film may be used as the lower insulating film. Since it is possible to more reliably form the contact hole in the lower insulating film compared with an organic insulating film, the electrical connection between the first electrode and the drain can be carried out in a reliable manner.

Problems solved by technology

However, since a reduction optical system is difficult to implement in imaging of the radioactive rays, the imaging is necessarily performed at the same magnification.

Therefore, there is a problem that the forming region of the photoelectric conversion element is reduced, and thus, the sensitivity decreases.

Therefore, there is a problem that the semiconductor layer deteriorates with moisture contained in the polyimide film which is an organic film, and thus, the photoelectric conversion element deteriorates.

Thus, there is a fear that the electrical connection between the second electrode and the bias line might not be carried out in a reliable manner.

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