JPS6223161A - Solid-state image pickup device with microlens - Google Patents

Abstract

PURPOSE:To increase light-gathering power by forming a microlens by an silicon nitride film. CONSTITUTION:An N-type semiconductor region 2 is shaped onto an silicon substrate 1, an silicon oxide film 4 and a polysilicon film 9 are deposited, an silicon nitride film 10 is deposited, and patterning so as to cover sections except the N-type semiconductor region 2 and oxidation are conducted, thus forming end sections covered with the silicon nitride film 10 to a tapered shape. When the silicon nitride film 10 and the upper silicon oxide film 4 are removed and the polysilicon film 9 is oxidized, the silicon oxide film 4 is shaped as the form is left as it is, and the silicon nitride film is deposited on the surface of the silicon oxide film 4 and flattened, thus shaping an silicon nitride lens 5, then depositing the silicon oxide film 4 on the surface of the silicon nitride lens 5. The silicon nitride lens 5 is held by materials having low refractive indices, thus displaying a convex lens effect.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid-state imaging device with a microlens that has improved light and sensitivity.

[Conventional technology]

43 (a) to Cd) show the conventional microlens, 4, 11 is the substrate, and 12 is the lens. When applying a microlens made with 5KL to a solid-state image sensor, the lens must be formed on the solid-state image sensor instead of the substrate 11.

An example of applying this lens to a solid-state image sensor is the literature (Y
asuo l5hihara, Kitgumi Ta
nlgaki, IEDM83. There are P497~).

Next, we will explain the formation processC First, 1m3G4C*
) on the substrate 11 of the transparent resin 12t as shown in FIG. 3(b).
t form. Next, as shown in FIG. 3(c), the transparent resin 12
ft (1 between each pixel when forming the solid-state imaging section on top)
Divide by enching. Next, Canada F111
By performing ft, each divided transparent resin 12 is melted and a lens-like formation is obtained due to surface tension as shown in FIG. 3(d). Since the thickness of the °C lens is determined by the thickness of the transparent resin 12, a focal length of 511@ can be ejected. The refractive index of the transparent resin 12 is about 1.5, and if the surface is made of air (with a refractive index of 1) or a substance with a refractive index smaller than 1.5, the refractive index as a lens is 4T2. This is a cross-sectional rirJ diagram showing the Tachibana-zukuri solid-state virtual image device with microlenses formed by the method of
13 is a p-type silicon substrate, 14 is an n-type semiconductor region that becomes a light receiving section, 15 is an n-type semiconductor region that becomes a drain, 16
is a field oxide film, 17 is a polysilicon layer, 18 is a
is a silicon oxide film.

19 is an aluminum layer, 20 silicon oxide films, 21 is an aluminum 4-light film, 22 is a flattening film, and 23 is a microlens.

[Problems to be Solved by the Invention] Since the conventional solid-state virtual image device with a microlens is constructed as described above and has a mechanical color, a transparent storage resin or the like with a refractive index of 1. If a substance close to 5 is provided, the lens effect will be lost and the light gathering power will decrease, causing problems with 5 and (5).

This invention was made to solve this problem, and it is possible to obtain high light-gathering power without losing the lens effect by applying a protective film to the surface of the solid-state imaging device. : The purpose is to obtain.

Means for Solving Problems C] In the solid-state imaging device with microphones according to the present invention, the microphones are formed of nitrided glue.

[Effect]

In this invention, the refractive index of the silicon nitride film forming the microlens is high, and the lens effect is not lost due to the other 9 in the vicinity.

〔Example〕

FIG. 1 is a cross-sectional view showing the -IIIj element of an embodiment of the solid-state virtual image device with microlens of the present invention, in which 1 is a p-type silicon substrate, 2 is an n-type semiconductor region which becomes a light receiving part, and 3 is a drain. nm semiconductor region 4 is a silicon oxide film, 5 is a silicon oxide film;
6 is a silicon nitride lens, 6 is a polysilicon gate, T is an aluminum wiring, and 8 is a field oxide film.

FIGS. 2(a) to 2(J) are diagrams showing the manufacturing process of the solid-state virtual image device with a microlens shown in FIG. 10 is a silicon nitride film.

The manufacturing process tt will be explained below.

First, as shown in FIG. 2(a)K, 517C, silicon substrate 1
An n-type semiconductor region 2 serving as a light receiving portion is formed on the top for use as a photodiode. Next w, Figure 2 (b) &
5, the silicon oxide film 4 is thermally oxidized or CVD
Formed at ℃ by method etc. Next, Fig. 2(c) shows K5.
Next, a polysilicon film 9 is deposited by, for example, LPCVD. Then, as shown in Figure 2(d)l'c, a thin silicon oxide film 4 is formed by thermal oxidation or CVD, and then, as shown in Figure 2(e)K, a silicon nitride film 10 is formed by LPCVD. The film is deposited by a method such as a method, and is then back-dipped to cover areas other than the n-type semiconductor region 2.

Next, as shown in FIG. 2 (Cf) 5, when oxidation is performed, the polysilicon fA9 at the bottom of the silicon nitride pattern 10 is oxidized, and only the unprocessed portion covered with the silicon nitride film 10 is oxidized. The end portion covered with the silicon nitride film 101 has a tapered shape called a bird's beak (bird's beak). 10 and the upper silicon oxide film 4 are removed. At this time, the upper silicon oxide film 4
The etching is stopped when the silicon oxide film 4 formed under the polysilicon film 9 is exposed. next,
When the polysilicon film 9 is oxidized by 5K as shown in FIG. After this, Figure 2 (+) will be shown.
K.

A silicon nitride lens 5 is formed by depositing a silicon nitride pattern on the surface of the silicon oxide film 4 by the LPCVD method or the like, and flattening the surface by using the Ninosen pack method or the like. Furthermore, after this, as shown in FIG.
deposit. Here, the refractive index of the silicon dioxide film is 2.
82. Since the refractive index of silicon oxide rA4 is 1.98, the silicon nitride lens 5 must be sandwiched between materials having a low refractive index, and exhibits a convex lens effect. This convex lens effect does not depend on the properties of the material of the filter or the like formed by trapping on the silicon oxide film 4.

In the above embodiment, the silicon oxide film 4 is formed as a layer after the silicon nitride lens 5 is formed.
This may be any other material as long as it is lower than the refractive index (2,82) of the nitrided material.

〔Effect of the invention〕

As explained above, in this invention, the microlens is formed of silicon dioxide having a high refractive index.

Due to the material and formation of the surface protective film of the solid-state imaging device, and the color filter, we hope to be able to obtain a solid-state imaging device with a microlens that has high light-gathering power without losing the convex lens effect.
It's effective.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing 10,000 elements of an embodiment of a solid-state imaging device with a microlens according to the present invention, and FIG.
Figure 1 shows the manufacturing process of the solid-state imaging device with a microlens; Figures 3 (a) to (d) show the process of forming a conventional microlens; Figure 4 shows the manufacturing process of a conventional microlens. It is a sectional view showing structure 3t of the attached solid-state imaging device. In the figure, 4 is a silicon oxide film, and 5 is a silicon nitride lens. In each figure, the symbol 16]- indicates the part corresponding to the number B]-f. Agent: Oiwa f'Ia (2 others, 1st)
Figure 5 Silicon nitride lens Figure 2 Figure 2 Figure 2 CI) Figure 3 La)

Claims (2)

[Claims] (1) In a solid-state imaging device with a microlens, in which a photodetecting section is arranged one-dimensionally or two-dimensionally on a substrate, and each microlens for condensing light is provided on the photodetecting section, each of the microlenses is formed using a silicon nitride film. A solid-state imaging device with a microlens, characterized in that it is formed of. (2) A solid-state imaging device with a microlens according to claim (1), wherein the microlens has a flat upper surface.