JPS6010883A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To obtain a solid-state image pickup device having the performance for obtaining an excellent picture by forming a light absorbing film on a shield film. CONSTITUTION:An insulating film 8 is formed on a light shield film 4 so as to cover the entire surface of a D type semiconductor substrate 1. The light absorbing film 9 is formed on the insulation film 8 so as to be placed on the light shield film only. In a television camera using a solid-state image pickup device with the constitution like this, the light contacting vertically onto the surface of this device substantially is made incident partly to the 1n channel diffusion layer 2 through the insulation films 8, 3 and the remaining light contacts the surface of the light absorbing film 9. Since the light contacted with the surface of the film 9 is absorbed effectively by the film 9 partly, the amount of light made incident again to the diffusion layer 2 after being contacted onto the surface of the lens is decreased less than that of a television camera using a solid-state image pickup device where the light is contacted directly to the entire surface of the light shield film 4. Thus, flare is reduced effectively.

Description

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

[Technical Background of the Invention] FIG. 1 is a sectional view showing a main part of one embodiment of a conventional solid-state imaging device. In the figure, 1 is a p-type semiconductor substrate, 2 is a first n-type diffusion layer formed on the width of the p-type semiconductor substrate, 3 is an insulating film formed on the surface of the p-type semiconductor substrate 1, and 4 is an insulating film 3 A light shielding film is formed on the p-type semiconductor substrate 1 so as to cover the entire surface thereof.

An opening 4 a is formed in the optical shield film 4 at a position above the first n-type diffusion layer 2 . Therefore, the optical signal enters the tenth type diffusion layer 2 and the p-type semiconductor substrate 1 thereunder through the opening 4a, and is photoelectrically converted therein, and the thus obtained signal charge is transferred to the tenth type diffusion layer 2. accumulated inside.

Reference numeral 5 denotes a second n-type semiconductor substrate 1 which constitutes a part of the readout means formed in the p-type semiconductor substrate 1 adjacent to the first n-type diffusion layer 2.
The type diffusion layer 6 is a first electrode constituting a part of the reading means provided in the insulation Ilaa so as to be located above the gap between the two diffusion layers 2 and 5. By applying a pulse voltage to 6, the signal charges accumulated in the 10th type diffusion layer 2 are transferred to the second n type diffusion layer 5.

7 is a second electrode provided in the insulating film 3 so as to be located on the 20th type diffusion layer 5;
The n-type diffusion layer 5 has a COD (char
ge coupled device). Therefore, the signal charge read out as described above is processed by the signal processing means (not shown) by this COD.
will be forwarded to.

[Problems with back assembly technology] In a television camera using a solid-state imaging device as described above, a portion of the light that has passed through the lens passes through the opening 4a of the light shielding film 4 of the solid-state imaging device and enters the first nth. mold diffusion layer 2
The remaining light hits the surface of the light shield film 4. On the other hand, the light shield film 4 is usually made of aluminum,
Such a light shield film 4 has extremely high light reflectance.

Therefore, the light that hits the surface of the light shield film 4 and is reflected is reflected by the lens, and then enters the tenth type diffusion layer 2 through the opening 4a near the part of the light shield film 4 that is hit by the light. This causes flare (f-Iare).

[Object of the Invention] The present invention takes the above-mentioned problem J into consideration and aims to provide a solid-state imaging device that can obtain good images.

[Summary of the Invention] The present invention provides a semiconductor substrate and a semiconductor substrate having two layers near the surface of the semiconductor substrate.
A light reception accumulation section that accumulates signal charges generated by photoelectric conversion and a readout means that reads out the signal charges accumulated in the light reception accumulation section, which are arranged in a dimension, and shield the readout means, and each of the light reception and accumulation sections. and a light shielding film covering the surface of the semiconductor substrate such that an opening is formed above the solid-state imaging device, characterized in that a light absorption film is formed on the light shielding film.

[Embodiments of the Invention] FIG. 2 is a cross-sectional view showing the main part of -RII of the solid-state imaging device according to the present invention. In the figure, the same parts as in FIG. 1 are indicated by the same reference numerals, and detailed explanation thereof will be omitted.

As shown in the figure, an insulating film 8 is formed on the light shield film 4 so as to cover the entire surface of the p-type semiconductor substrate. The light absorption film 9 is formed as shown in FIG. This light absorption film 9
covers at least a portion of the entire surface of the light shield film 4.

Note that the light absorption film 9 is made of chromium (Cr), molybdenum (M
O), a metal (opaque) with a higher light absorption rate than that of aluminum, such as silicide (e.g. MoS i ), or a mixture of gelatin and a dye such as black (opaque), etc. The thickness is about 1 to 3 μm.

Therefore, in a television camera using a solid-state imaging device with such a configuration, a portion of the light that passes through the lens and hits the surface of the solid-state imaging device substantially perpendicularly is transmitted through the insulating film 8.
3 directly enters the first n-type diffusion layer 2 , and the rest hits the surface of the light absorption film 9 .

A portion of the light hitting the surface of the light absorption film 9
Because it is effectively absorbed by
The intensity of light re-entering the 0-type diffusion layer 2 is reduced compared to that of a television camera using a conventional solid-state imaging device in which there is no light absorption film 9 and the entire surface of the light shielding film 4 is directly exposed to light. Therefore, flare is also effectively reduced. The degree of reduction in flare increases as the proportion of the surface of the light shielding film 4 covered by the light absorption film 9 increases and as the light absorption rate increases.

FIG. 3 is a sectional view showing another embodiment of the main part of the solid-state imaging device according to the present invention. In the figure, the same parts as in FIG. 2 are indicated by the same reference numerals. As shown in the figure, in this example, the light absorption film 9
extends to the inside of the opening 4a of the light shield film 4.

The other configurations are the same as the solid-state imaging device shown in FIG.

According to such a configuration, in addition to the effect of reducing flare, the following advantages can be obtained. That is, if the light absorbing film 9 does not extend to the inside of the opening 4a of the light shielding film 4, the light that passes through the lens and hits the surface of the solid-state imaging device substantially perpendicularly becomes light. The light directly hits the peripheral edge 10 of the opening 4a of the shield film 4, is reflected there, and obliquely enters the first n-type diffusion layer 2 (and the p-type semiconductor substrate 1). As a result, the light thus incident reaches a portion of the p-type semiconductor substrate 1 directly below the second n-type diffusion layer 5, and is photoelectrically converted there. The charges obtained thereby directly enter the 20th type diffusion layer 5 without being affected by the pulse voltage applied to the first electrode 6, and smear (smear) occurs.
mear). Therefore, as shown in FIG. 3, the light absorption p149 is
By extending to the inside of the lens a, the light a passes through the lens and enters the gap 9 between the light absorbing films 9.
From a, the light passes through the insulating film 8.3 and only the area inside the peripheral edge 10 of the opening 4a of the light shield film 4, without hitting this peripheral edge 10. Therefore, the first n-type diffusion layer 2
Since the incident light a is photoelectrically converted only in the first n-type diffusion layer 2 and the p-type semiconductor substrate 1 immediately below it, the second
Smear caused by direct charge entering into the n-type diffusion layer 5 is effectively suppressed.

[Effects of the Invention] As explained above, according to the present invention, it is possible to provide a solid-state imaging device that can obtain good images.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a main part of an embodiment of a conventional solid-state imaging device, FIG. 2 is a sectional view showing a main part of an embodiment of a solid-state imaging device according to the present invention, and FIG. 3 is a sectional view showing a main part of an embodiment of a solid-state imaging device according to the present invention. FIG. 3 is a cross-sectional view showing another aspect of the main part of the solid-state imaging device according to the present invention. 1... P-type semiconductor substrate 2... First n-type diffusion layer 3.
...Insulating film 4...Light shield film 5-...Second n-type diffusion layer 6...First electrode 7...Second electrode 8...
Insulating film 9...Light-absorbing film application agent Patent attorney Kikuchi 5]

Claims (2)

[Claims] (1) A semiconductor substrate, a light receiving and accumulating section arranged two-dimensionally near the surface of the semiconductor substrate and accumulating signal charges generated by photoelectric conversion, and a reading means for reading out the signal charges accumulated in the light receiving and accumulating section. , a solid-state imaging device comprising a light shielding film that shields the readout means and covers the surface of the semiconductor substrate such that an opening is formed above each of the light receiving and accumulating sections, wherein a light shielding film is provided on the light shielding film; A solid-state imaging device characterized by forming an absorption film. (2) The light-absorbing film extends above the opening to the inside thereof.
The solid-state imaging device described in .