JPS61281549A - Solid-state image pickup element - Google Patents

Abstract

PURPOSE:To reduce the quantity of beams reflected, and to increase the amount of beams projected to a beam-receiving section by forming an antireflection film onto a semiconductor substrate with the beam-receiving section and a protective film for the beam-receiving section in a monolithic manner. CONSTITUTION:An antireflection film 1 is formed onto a protective film 4 by using a plasma polymerization method. When a thin-film in several hundred Angstrom is shaped by using per-fluorobutene-2 as a monomer gas on the formation of the antireflection film 1 through the plasma polymerization method, a plasma polymer containing fluorine in said substance has a small refractive index as 1.36-1.39 and excellent transparency, and the quantity of incident beams higher than conventional devices by 2-5% is acquired. Even when a magnesium fluoride thin-film is evaporated and shaped under normal conditions as the antireflection film, the same effect is recognized. Accordingly, the loss of the quantity of incident beams reaching a beam-receiving section is reduced, and the amount of beams is increased by 2-5%, thus largely improving the sensitivity of a solid-state image pick-up element.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a solid-state image sensor, and particularly relates to its optical characteristics,
In particular, it relates to improved sensitivity.

[Conventional technology]

Traditionally produced solid-state image sensors are black and white elements ψ
In the case of PSG (phosphorus doped s, t,
, Oz), , q or a protective film made of an organic polymer is currently formed, and when a color filter is formed in a mohasic manner in a color element, the outermost layer is made of an organic polymer.

FIG. 2 shows a cross-section of an example of a conventional color solid-state image pickup device. In the figure, reference numeral 5 is provided on the top of a semiconductor substrate, and light receiving sections 1 and 6 for receiving light are constructed on the substrate. The PSG films 6-F, 2 and 3 are respectively formed on the PSG film 6-F.

Yellow, a color separation filter, 4, is formed on the filter, and the color separation filter, 4, is formed on the filter. (a layer of silky polymer), which forms the top layer of the solid-state imaging device. Further, the protective film is usually made of an acrylic photosensitive polymer and has a refractive index of about 1.5.

In conventional solid-state imaging devices like this, the refractive index of the material in the top layer on the surface is approximately 165 to 1.6 at room temperature for both black and white and color images. .

[Problem that the invention seeks to solve]

By the way, in a solid-state image sensor where the top layer is coated with a material with a refractive index of about 1.5, part of the incident light is reflected on the surface and does not reach the light receiving part, so the efficiency of the incident light is reduced. This means that it cannot be used often, and sufficient characteristics such as sensitivity under low illuminance cannot be obtained.

This invention was made to solve the above-mentioned problems, and provides a highly sensitive solid-state image sensor that can suppress the loss of 10% of the amount of light incident on the light receiving part of the image sensor due to reflection on the surface layer. The purpose is to

[Means for solving problems]

The solid-state image sensor according to the present invention has an antireflection film monolithically provided on a semiconductor substrate having a light receiving section and a protective film for the light receiving section.

[Effect]

In this invention, since the anti-reflection film is monolithically provided on the protective film of the light receiving section, the amount of reflected light reflected from the surface of the film can be reduced, and therefore the amount of light incident on the light receiving section can be increased. .

[Embodiments of the invention]

An embodiment of the present invention will be described below.

FIG. 1 shows a cross-sectional structure of a color solid-state image sensor according to an embodiment of the present invention. In this element, a color filter, 4 is a protective film using an organic polymer, 1 is an anti-reflection film formed into a thin film using a plasma polymerization method on the protective film 4,
The anti-reflective IPJ I may be made of an organic material or a non-reflective material, and can be formed by a sputtering method, in addition to the method described above.
A vapor deposition method such as a cluster ion beam method may also be used.

Next, the effects will be explained.

Now, anti-reflection +1. ．． To explain the case where 1% of the plasma polymer 1 is formed using the plasma polymerization method, when several hundred thin films are formed using perfluorobutene-2 as the monomer gas, the refractive index of the plasma polymer 1 containing this fluorine is 1.36.
- Small size of ~1.39 and good transparency, incident light amount is 2~5%
I got something expensive. A similar effect was also observed when a thin magnesium fluoride film I9 was deposited on a regular strip 1 as the antireflection film.

Note that in the actual implementation, an image sensor in which light receiving sections are arranged two-dimensionally has been described, but the present invention can also be applied to a near sensor in which light receiving sections are arranged one-dimensionally, and similar effects can be obtained.

Further, in the above embodiment, an antireflection film was applied only to the outermost layer of the color solid-state image sensor in which the color filter was formed monolithically, but as in another embodiment of the present invention shown in FIG. An anti-reflection +1- film may be formed on both sides, and the same effect as described above can be expected.

Further, although the above embodiments have been described with respect to color solid-state image sensors, the present invention can of course be applied to black and white solid-state image sensors, and the same effects as in the above embodiments can be achieved.

〔Effect of the invention〕

As described above, according to the present invention, since the antireflection film is monolithically formed in the solid-state image sensor, the amount of incident light reaching the light receiving portion is reduced by 10%, and the amount of light is reduced by 2%.
This results in an increase of ~5%, which has the effect of greatly improving the sensitivity of solid-state image sensors.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a solid-state imaging device according to an embodiment of the present invention, FIG. 2 is a sectional view showing a conventional device, and FIG. 3 is a sectional view showing another embodiment of the invention. 1 - Antireflection film, 2 - Cyan color separation filter. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) In a solid-state imaging device comprising a semiconductor substrate on which a light-receiving portion is formed on its surface region and a protective film provided on the semiconductor substrate, an antireflection film is monolithically formed on the protective film. A solid-state image sensor characterized by: (2) A color solid-state image sensor, characterized in that the light receiving section, the antireflection film, and the color separation filter located between them are monolithically formed. The solid-state image sensor described in .