JPS59113662A - Solid state image pickup element - Google Patents

Abstract

PURPOSE:To contrive to dissolve the smear phenomenon of a solid state image pickup element by a method wherein an amorphous semiconductor layer is provided at the deep part of an image pickup substrate. CONSTITUTION:An image pickup substrate 1 of semiconductor constitution is constructed of a semiconductor substrate 10 consisting of P type silicon, an amorphous silicon layer 11 having high minute defect density and formed on the substrate 10, and an epitaxial layer 12 consisting of P type silicon laminated on the layer 11. The manufacturing method of the image pickup substrate 1 is that, for example, the amorphous silicon layer 11 is formed at first by high-frequency sputtering according to argon plasma on the semiconductor substrate 10 consisting of P type silicon. At this time, by changing pressure of argon and the distance between the electrodes of sputtering, minute defect density of the amorphous silicon layer 11 can be set to an arbitrary value. Then the upper surface part of the amorphous silicon layer 11 is heat-treated at a high temperature for a short hour, at 900 deg.C for 30min for example, to crystallize the layer. After then, the P type silicon epitaxial layer 12 is grown on the crystallized surface of the amorphous silicon layer 11.

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to a solid-state imaging device that takes images.

(B) Prior Art This type of solid-state image sensor has a large number of light receiving sections arranged in pixel units on the surface of an imaging substrate having a semiconductor structure, and each of these light receiving sections receives photoelectric signals from incident image light. A conversion takes place.

However, in a conventional solid-state image sensor, the incident light reaches a deeper part than the light receiving part of the imaging board, and photoelectric conversion occurs in this deep part, so the photocharges generated in this deep part are diffused and transferred. and flows into the adjacent light receiving section.
We met. This caused a smear phenomenon in which white bleeding appeared in the reproduced image.

On the other hand, in order to suppress the smear phenomenon, a high-concentration impurity layer containing high-concentration impurities, such as oxygen ions, is introduced deep into the imaging substrate. A solid-state imaging device has been proposed in which the effective diffusion distance of photoelectric charges photoelectrically converted in a deep part is reduced, and the movement of the photocharges is suppressed.

However, when applied to various conventional devices, there is a limit to the trapping ability of photocharges in the highly concentrated impurity layer, and the above-mentioned smear phenomenon has not yet been eliminated. Moreover, when introducing impurities into the high-concentration impurity layer, for example when introducing oxygen ions, a long thermal oxidation treatment is required, making the manufacture of this type of device complicated.

? →Object of the Invention The present invention has been made in view of the above-mentioned points, and provides a solid-state image sensing device 'a-'a- which aims to eliminate smear development.

(2) Structure of the Invention The solid-state imaging device of the present invention has an amorphous semiconductor layer provided deep within its imaging substrate.

Example The figure shows an embodiment of the solid-state imaging probe of the present invention.

In this figure, (1) is an imaging substrate having a semiconductor structure, which includes a semiconductor base portion made of P-type silicon, and the base body 11Q.
It is composed of an amorphous silicon layer 1υ with a high microdefect density formed thereon, and a p-type silicon layer laminated on the amorphous silicon layer uυ.

Here, a specific example of the method for manufacturing the imaging substrate (1) will be shown. First, an amorphous silicon layer (lυ) is formed on a semiconductor substrate 1 (0) made of P-type silicon by wave sputtering using argon plasma. At this time, argon pressure and sputtering electrodes are applied. By changing the distance between the two layers, the microdefect density of the amorphous silicon layer ('υ) can be set to an arbitrary value.For example,
Interelectrode distance 3 crn, argon pressure 2 x 10' TOrr
% Target is crystalline silicon, sputtering time 1
An amorphous silicon layer with a thickness of 1.0 to 1.5 μm is obtained under conditions of .times.

Next, the upper curved portion of the amorphous silicon layer Uυ is heated at a high temperature for a short period of time, for example, 9 [JO'030] to crystallize -C. In addition, at this time, heat! If the a degree is set to 1000''C and the heating time is set to 1 o'clock, the entire amorphous silicon layer 1.lυ will be crystallized.

Thereafter, P was deposited on the crystallized surface of the amorphous silicon layer 1.1υ using a normal vapor phase epitaxial method.
A layer H of silicone is grown.

The light is 1f19.・；Shun13) is each light receiving part +2)(2
), +4J14J is each transmission channel t3.
) 13) and the other side of each light receiving section (2) (2), +5115) is an overflow drain consisting of an N-type head region provided within the channel stopper 14114). be. 16) is an insulating film made of transparent silicon dioxide formed on the surface of the lobster layer (121) of the imaging substrate (1).
7) is an insulating film (6) on the transfer channel +3) (33).
), 181+8) is a channel gate placed on the insulating film (6) between each of the light receiving parts (21(2) and each transfer channel +3313J), 191+9 is the channel gate located above overflow drain 15
This is an overflow control gate disposed on the channel stopper 1J14 with 51 inside, with an insulating film 16) interposed therebetween.

Thus, the image sensor is configured such that the image light incident on the light receiving portion t2J (21) provided in the epitaxial layer u4 is transmitted to the light receiving portion t21 (2) and the epitaxial layer adjacent to the light receiving portion (2) (2). Photoelectric conversion occurs at the layered point,
As a result, photocharges obtained according to the intensity of the incident light are accumulated in the light receiving section +2) (23).

On the other hand, the image light incident on the amorphous silicon layer Uυ located deeper in the light receiving section (21121) is photoelectrically converted in this amorphous silicon layer Uυ.

However, the amorphous silicon layer has a very high defect density, so compared to crystalline silicon,
The trapping effect on photocharges is extremely small, and the photocharges photoelectrically converted by this amorphous silicon MtlaK,
In this case the electrons are immediately trapped. In other words, harmful electrons that cause smear phenomenon in reproduced images are transmitted to the light receiving section +21.
It will disappear by the time it diffuses to 2J.

Only the electrons accumulated in the light receiving part (2) are transferred to the transfer channel 1.3 via this channel gate (8) by applying a positive high voltage to the channel (1.8). ) will be introduced. And this transfer channel/!
/13) By applying a driving pulse to the upper transfer electrode (7), the electrons introduced into the transfer channel (3) are transferred and output to the outside as an image signal.

(F) Effect As is clear from the above description, the solid-state image sensor of the present invention has an amorphous semiconductor layer provided deep in the image sensor substrate, so that the image light incident on the amorphous semiconductor layer is The photoelectrically converted charges are immediately trapped in the amorphous semiconductor layer, which has a much lower defect density than the crystalline semiconductor layer, and the harmful charges can be annihilated, resulting in a high-quality product without smearing. images are obtained. Moreover, by providing an amorphous semiconductor layer, it is possible to eliminate the need for a high concentration impurity layer for trapping photocharges, which was required in conventional devices, and it is hoped that the manufacturing of the solid-state imaging device will be simplified.

[Brief explanation of drawings]

The figure is a cross-sectional view of one embodiment of the solid-state imaging device of the present invention, (11 is an imaging substrate, (2) is a light receiving part, (10) is a semiconductor substrate, ul is an amorphous silicon layer, 11:<1 is The Evitakal layer is removed.

Claims (1)

[Claims] 1) Using an imaging substrate with a semiconductor structure in which a crystalline semiconductor layer of one conductivity type is laminated on an amorphous semiconductor layer, a large number of light-receiving parts of a conductivity type opposite to that of the semiconductor layer are arranged in the crystalline semiconductor layer on the surface of the substrate. A solid-state image sensor characterized by the following structure.