JPH02238666A - Solid-state image sensing device - Google Patents

Abstract

PURPOSE:To enable two layers to be used as internal wiring layers for a thin film transistor and enable highly free wiring for driver circuit based on the thin film transistor and improve integration density by providing a second interlayer insulating film. CONSTITUTION:A photosensor layer 27 held between a transparent conductive film 26 and a conductive film 29, a second interlayer insulating film 28 held between the transparent conductive film 26 and the conductive film 29, the transparent conductive film 26 electrically connected to polycrystalline silicon 22 and a gate electrode 24, the conductive film 29 electrically connected to the polycrystalline silicon 22 and the gate electrode 24, are laminated and integrated in the order of the transparent conductive film 26, the photosensor layer 27, the second interlayer insulating film 28, the conductive film 29. Thus, integration density and yield can be increased, and production processes and cost can be reduced.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a solid-state imaging device.

[Prior Art] Conventionally, a solid-state imaging device that integrates a driver circuit composed of thin film transistors and a photosensor is described in the Proceedings of the 16th Solid-State Devices and Materials Conference P559-P.
562, it had a structure in which the incident imaging light was not passed through the transparent substrate.

Another example of the prior art is shown in FIG. 1 of Japanese Patent Laid-Open No. 61-1059'80 filed by the present applicant. The internal wiring of the thin film transistor is shared with the sensor electrode, but the transparent electrode is not shared with the internal wiring of the thin film transistor [Problem to be solved by the invention] However, in the prior art described above, the internal wiring of the thin film transistor is Therefore, it was not possible to increase the integration density of solid-state imaging devices. In particular, in solid-state imaging devices called contact image sensors that use an optical sensor array with the same width as the document, the length of the solid-state imaging device is 100 mm (
The B5 size is approximately 182 mm or more, and the power supply wiring for the driver circuit integrated inside is also over 100 mm long. Lower the resistance of the power supply wiring,
Since it is desired to reduce the switching noise of the driver circuit of the solid-state imaging device, it is desirable that the pattern width of the power supply wiring is large. Furthermore, in order to increase the integration density of the solid-state imaging device, it is necessary to form power supply wiring on the thin film transistor. There was a problem in that the conventional technology, in which the thin film transistor had only one layer of internal wiring, could not meet the technical and economic demands.

The present invention is intended to solve these problems, and its purpose is to provide a solid-state imaging device with excellent characteristics at a low cost and with a high yield and a small number of manufacturing processes.

[Means for Solving the Problems] The solid-state imaging device of the present invention includes: a) A driver circuit constituted by an optical sensor and a thin film transistor is integrated on a transparent substrate, and light is incident through the transparent substrate. b) Photosensor layer 27 sandwiched between transparent conductive film 26 and conductive film 29; C) Second interlayer insulating film 28 sandwiched between transparent conductive film 26 and conductive film 29; d) Polycrystalline silicon 22 and gate electrode. 24; C] Polycrystalline silicon 22; conductive film 29, electrically connected to gate electrode 24; f) Transparent conductive film 26, photosensor layer 27,
It is characterized in that an interlayer insulating film 28 and a conductive film 29 are stacked and integrated in this order.

[Example] FIG. 1 is a sectional view of each main process of a solid-state imaging device in an example of the present invention.

The transparent substrate 21 is a quartz substrate, a sapphire substrate, a glass substrate, or the like, which has light transmittance and electrical insulation properties. The polycrystalline silicon 22 has a source electrode portion, a drain electrode portion, and a channel portion of the thin film transistor. Gate oxide film 26
is formed by thermally oxidizing polycrystalline silicon 22. The gate electrode 24 is formed of a polycrystalline silicon material or the like, and is also used as a mask for ion implantation using self-alignment gate technology. The first interlayer insulating film 25 is formed by forming an S102 film or a Si3N film by a CvD method, and is selectively formed by a photolithography method on the polycrystalline silicon 22 and the gate electrode 24 that need to be electrically connected to the transparent conductive film 26. Drilling is done.

At this time, holes are also formed in the gate oxide film 26 at the same time or in an additional step. Next, the transparent conductive film 26 is formed using a transparent conductive material such as indium tin oxide (TO) by sputtering or the like. Subsequently, the transparent conductive film 26 is patterned as a wiring material for a thin film transistor, an electrode for a light sensor, etc. by the photo-IJ nography method. (See FIG. 1 (.Z) above.) Through the above steps, part of the source, gate, and drain electrodes of the thin film transistor and the light incident side electrode of the photosensor are electrically connected.

Continuing with the above steps (see FIG. 1(b)), the optical sensor layer 27 is formed by sequentially laminating and patterning, for example, non-quality silicon materials of P, N, and N conductivity types using a plasma O'VD device or the like. . Subsequently, the second interlayer insulating film 28 is
It is formed by spey coating a Sin film, a Si3N4 film, a polyimide film, a photoose film, etc. by the D method. (See FIG. 1 Cb'l above.) Subsequently (see FIG. 1 (C)), polycrystalline silicon that needs to be electrically connected to the conductive film 29 is applied to the second interlayer insulating film 28 by photolithography. 22, the gate electrode 24 and the photosensor layer 27 are selectively drilled. At this time, holes are also formed in the first interlayer insulating film 25 and the gate oxide film 23 at the same time or in an additional step. Next, the conductive film 29 is formed by sputtering or the like using an aluminum alloy material such as At-Si-Ou. Subsequently, the conductive film 29 is patterned by photolithography as a wiring material for a thin film transistor and an electrode for a photosensor. Through the above steps, all the electrodes of the thin film L transistor and each electrode of the optical sensor are electrically connected. Finally, a protective film 30 is formed and patterning is performed to form holes for bonding pads. (See FIG. 1(C) above.) [Effects of the Invention] As described above, the present invention has the following effects.

a) By providing the second interlayer insulating film 28, two layers, that is, the transparent conductive film 26 and the conductive film 29, can be used as the internal wiring layer of the thin film transistor, so the degree of freedom in wiring the driver circuit using the thin film transistor is increased. For example, since the power supply wiring can be laid out on the thin film transistor, the pattern width of one power supply wiring can be widened, and the area of the driver circuit can be made small.The shielding effect of the power supply wiring on the thin film transistor improves the signal-to-noise ratio performance of the solid-state imaging device. b) The layer added to the structure of the conventional solid-state imaging device is the second interlayer insulating film 2.
8, it not only has a high yield and low cost due to fewer manufacturing processes, but also has excellent characteristics as described above, so it has the effect of extremely high cost performance.

The present invention is particularly effective in reducing costs and improving characteristics of contact type image sensors.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing each main process of an embodiment of the solid-state imaging device of the present invention. 21...Transparent substrate 22...Polycrystalline silicon 26...
...Gate TS film 2, 4...Gate electrode 5...First interlayer insulating film 6...
...Transparent conductive film 7...Photo sensor layer 8...Second interlayer insulating film 9...
...Conductive film O......Protective film or higher

Claims (1)

[Claims] a) A solid-state imaging device in which a driver circuit including an optical sensor and a thin film transistor is integrated on a transparent substrate, and light is incident through the transparent substrate, b) a transparent conductive film 26 and a conductive film 29; a sandwiched photosensor layer 27; c) a second interlayer insulating film 28 sandwiched between the transparent conductive film 26 and the conductive film 29; d) a transparent conductive film electrically connected to the polycrystalline silicon 22 and the gate electrode 24; 26, e) polycrystalline silicon 22, a conductive film 29 electrically connected to the gate electrode 24; A solid-state imaging device characterized in that the solid-state imaging device is laminated with.