JP2987894B2 - Solid-state imaging device and method of manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a solid-state imaging device having an on-chip color filter and a method for manufacturing the same.

[Prior Art] A conventional solid-state imaging device having an on-chip color filter is described in, for example, Nikkei Microdevices December 1989, p.66.
As described on page 68, the color filter has an organic compound film such as gelatin or casein colored with an organic dye and formed so as to cover the light-receiving diode portion.

That is, in the conventional solid-state imaging device, as shown in FIG. 6, a p-type well region 401 formed on the surface of an n-type semiconductor substrate 402, a photodiode n-type region 403, a p ⁺ -type channel stopper region 404, a diffusion layer region such as an n-type buried channel region 405; and a first gate electrode 41 provided on the substrate.
7, a lower layer portion composed of the second gate electrode 418 and the insulating film 406 for transferring the charge photoelectrically converted by the photodiode to the peripheral circuit, the condensing microlens 410, and the flattening resin film 40
9, first and second color filter films 408 and 412, protective insulating film 4
07, which is composed of a light shielding film 411 and the like, and is divided into an upper layer portion for condensing, separating, and shielding incident light. In the conventional solid-state imaging device, the light-shielding film 411 is formed of aluminum, and the color filter films 408, 412 and the like are formed of a resin film such as gelatin or casein dyed in four colors of magenta, cyan, yellow, and green. First to fourth color filter protective insulating films 413 to 416 made of resin for the filter film
The light collecting microlens 410 is also formed of a transparent resin film.

[Problems to be Solved by the Invention] In the conventional solid-state imaging device, even if an attempt is made to increase the resolution of the imaging device by miniaturizing the area of the light receiving section, fine processing cannot be performed because the color filter film is made of a resin film. It was difficult to improve the resolution. In addition, when forming the microlens for condensing, the fluidization phenomenon due to the glass transition of the microlens film is applied. However, when the microlens layer is heated, there is a problem that the color filter film is deteriorated or decolorized. Occurred. In addition, when a solid-state imaging device chip is incorporated in a package, the processing temperature is severely restricted, and a defect is easily generated because a resin, which is a material having low mechanical strength, is used.

[Means for Solving the Problems] A solid-state imaging device having an on-chip color filter according to the present invention uses a colored glass film as a color filter film, and this also serves as a condenser lens. This colored glass is composed mainly of silicon oxide, Au, Cu, Se,
It contains metal elements such as Cd, Fe, Cr and Co or compounds such as oxides, sulfides and halides of these metal elements as coloring materials.

Further, the method for manufacturing a solid-state imaging device having an on-chip color filter according to the present invention uses a step of forming a water-repellent organic compound pattern having an opening only in a desired light-receiving portion and a hydrolysis reaction of a halogenated silane. And a step of selectively forming a color filter film in an opening of the water-repellent organic compound pattern and a step of removing the water-repellent organic compound by a desired number of colors.

[Example] Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a reference example of the present invention, and FIG.
FIGS. 7A to 7C are cross-sectional views illustrating a manufacturing process according to the present embodiment during a manufacturing process. In the present embodiment, a diffusion layer region such as a p-type well region 101, a photodiode n-type region 103, a p ⁺ -type channel stopper region 104, an n-type buried channel region 105 formed on the surface of an n-type semiconductor substrate 102, The structure of the lower layer portion, which includes the first gate electrode 117, the second gate electrode 118, the insulating film 106, and the like provided on the substrate and transfers the charge photoelectrically converted by the photodiode to the peripheral circuit is the same as that of the conventional example. is there.

However, in the present reference example, an upper layer portion above the insulating film 106 that collects, separates, and blocks incident light is different from the conventional example. That is, a high melting point metal such as tungsten is used for the light shielding film 111, and the protective insulating film 10
7 are formed. The spectrum of the color of the incident light is shown in this cross-sectional view, including the first color filter film 108 and the second color filter film 112 made of colored glass containing silicon oxide as a main component, hidden in the depth direction of the paper. This is done by the third and fourth color filter films. The incident light is condensed by a condensing microlens mainly composed of silicon oxide.
Performed by 110. The first to fourth color filter protective insulating films 113 to 116 are formed of silicon oxide, and prevent color mixture at the time of forming the color filter film.
It has a role of protecting the color filter film during the fine processing of the color filter film. Further, the planarizing insulating film 109 prevents the shape of the condensing microlens 110 from becoming non-uniform due to a step in the lower layer.

Next, a manufacturing method of the reference example will be described with reference to FIGS.

First, the p-type well region 101, the photodiode n-type region 103, and the p ⁺ type channel stopper region 10 are selectively formed on the surface of the n-type semiconductor substrate 102 by ion implantation or thermal diffusion.
4. An n-type buried channel region 105 is formed, and then a first gate electrode 117 and a second gate electrode 118 are formed using polycrystalline silicon. A silicon oxide film is formed by thermal oxidation for insulation between the silicon substrate and the first gate electrode, and CVD is used for insulation of the first and second gate electrodes and protection of the second gate electrode.
A silicon oxide film is formed by a method. These insulating films are collectively referred to as an insulating film 106. The method of manufacturing the lower layers such as the photoelectric conversion unit and the charge transfer unit of these solid-state imaging devices is not different from the conventional method.

Next, an upper layer portion for condensing, dispersing, and shielding light is formed. First, a tungsten film is formed on the insulating film 106, and a portion above the photodiode n-type region 103 is selectively removed to form a light-shielding film 111. Further, in order to protect the light shielding film 111, a protective insulating film 107 made of silicon oxide is formed by a plasma CVD method (FIG. 2A).

Colored glass to be a color filter film is formed by a CVD method or a coating method. As the CVD method, a reduced pressure CVD method using an alkoxysilane and an organic metal can be considered. As a coating method, it is conceivable to mix an organic metal chelate or the like into a silica coating solution. The colored glass film thus formed is processed so as to leave only the desired photodiode portion, and the first color filter film 108 is formed.
[FIG. 2 (b)].

On the first color filter film 108, a silicon oxide film to be the first color filter protective film 113 is formed by the CVD method, and the second oxide film is formed thereon by the same method as that performed in FIG. A color filter film 112 is formed. At this time, a desired color is obtained by changing the metal element and the like mixed into the colored glass [FIG. 2 (c)].

2C is repeated to form four color filter films and their protective films 114 to 116, and then a planarizing insulating film 109 is formed by a coating method. Thereafter, a boron-phosphorus glass film is formed, finely processed so as to leave only above the light receiving portion, rounded by reflow heat treatment, and a condensing microlens 110 is formed. This embodiment shown in FIG. Can be formed.

In this embodiment, the light collecting microlens 110 made of the BPSG film is used, but a lens made of a conventional resin may be used instead.

FIG. 3 is a cross-sectional view showing a first embodiment of the present invention, and FIGS. 4 (a) to 4 (c) are cross-sectional views in the middle of a manufacturing process for explaining the manufacturing process of the present embodiment. It is.

In this embodiment, the portions below the light-shielding film 211 are the same as those in the previous embodiment, and therefore, the same portions are denoted by the same reference numerals in the last two digits, and redundant description is omitted.

In this embodiment, the first color filter film 208, the second color filter film 212, and the remaining two color filter films (not shown in the cross-sectional view) are in contact with the insulating film 206, and a part of the color filter film is in the light-shielding film 211. They are provided to overlap. By doing so, it is possible to prevent light from leaking from between the color filter film and the light-shielding film and entering the n-type region for the photodiode. Further, since an interlayer film between the color filter films is unnecessary, the total film thickness of the upper layer can be reduced, the attenuation of incident light can be reduced, and the sensitivity of the device can be increased.

Next, the manufacturing method of this embodiment will be described with reference to FIGS. 4 (a) to 4 (c).
The steps up to the formation of the light shielding film 211 are the same as the steps of the previous embodiment.

Thereafter, a water-repellent organic compound film 219 having an opening pattern such that a part of the light-shielding film 211 is exposed is formed only on a desired photodiode region. As the water-repellent organic compound, a fluororesin or a compound obtained by fluorinating the surface of a resist is suitable. Next, the first color filter film 208 is selectively formed by a selective vapor deposition method utilizing the phenomenon that the hydrolysis reaction of silane tetrachloride varies depending on the difference in water repellency of the substrate surface [FIG. 4 (b)]. ].

Thereafter, the water-repellent organic compound film is removed, and the second color filter film 212 is formed in the same manner as the first color filter film 208 using the water-repellent organic compound film 220 having an opening at the portion [fourth embodiment]. Figure (c)].

By repeating the steps of FIGS.
After forming a color filter film corresponding to each type of color, finally, a protective insulating film 207 is formed by a CVD method, and after flattening, to produce a condensing microlens 210, so that it remains only on the light receiving portion. When a boron-phosphorus glass film is processed and fluidized and rounded, an image sensor shown in FIG. 3 is formed.

FIG. 5 is a sectional view showing a second embodiment of the present invention. In this embodiment, the portions below the light-shielding film 311 are the same as those in the first embodiment, and the corresponding portions are denoted by the same reference numerals with the same lower two digits, and redundant description is omitted.

This embodiment is different from the previous embodiments in that each of the color filter films 308 and 312 also serves as a condensing microlens. The color filter film of this embodiment is doped with boron and phosphorus when growing silicon oxide by the selective growth method,
Thereafter, it is formed by heating and fluidizing.

[Effects of the Invention] As described above, in the present invention, the color filter film is formed of colored glass. Therefore, according to the present invention, the fine processing technology used in the LSI manufacturing process can be applied as it is. The pattern can be miniaturized down to the submicron unit. In addition, the color filter film is not greatly deteriorated by the microlens forming process or the heat treatment at the time of assembling, and decolorization does not occur. Further, since the glass film has sufficient mechanical strength, the rate of occurrence of defects in an assembling process or the like is reduced, and handling of wafers and chips becomes easy.

Further, since the color filter film of the present invention can also be formed by a selective growth method, an interlayer film between the color filter films is not required by this method, so that attenuation of incident light is reduced and sensitivity of the device is reduced. Can be improved.

Further, since the color filter film of the present invention can be heated and fluidized, and the optical properties are not changed by this, the color filter film can be processed into a condensing microlens. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a reference example of the present invention, and FIGS.
FIG. 3C is a cross-sectional view showing a state in the course of manufacturing the reference example, FIG. 3 is a cross-sectional view showing the first embodiment of the present invention, and FIGS.
(C) is a sectional view showing a state in the course of manufacture of the first embodiment,
FIG. 5 is a sectional view showing a second embodiment of the present invention, and FIG. 6 is a sectional view of a conventional example. 101, 201, 301, 401: p-type well region, 102, 202, 30
2, 402 n-type semiconductor substrate, 103, 203, 303, 403 n-type region for photodiode, 104, 204, 304, 404 p ⁺
Mold channel stopper region, 105, 205, 305, 405 ... n-type buried channel region, 106, 206, 306, 406 ... insulating film, 107, 207, 407 ... protective insulating film, 108, 208, 308, 40
8 ... first color filter film, 109 ... planarization insulating film, 11
0, 210, 410: Condensing micro lens, 111, 211, 31
1, 411: light shielding film, 112, 212, 312, 412: second color filter film, 113, 413: first color filter protective insulating film, 114, 414: second color filter protective insulating film, 11
5, 415: Third color filter protective insulating film, 116, 416 ...
... Fourth color filter protective insulating film, 117, 217, 317, 417
... First gate electrode, 118, 218, 318, 418... Second gate electrode, 219, 220.

Claims (5)

(57) [Claims] 1. A solid-state imaging device having an on-chip color filter in which a color filter film is formed of colored glass, wherein the color filter film also serves as a condenser lens. 2. The solid-state imaging device according to claim 1, wherein the colored glass contains silicon oxide as a main component. 3. The solid-state imaging device according to claim 1, wherein the coloring material of the colored glass is a metal element or a metal compound. 4. The solid-state imaging device according to claim 1, wherein a part of said color filter film is formed in contact with a part of said light shielding film. 5. A step of forming a water-repellent organic compound pattern having an opening only in a desired light-receiving portion, and selectively coloring the opening of the water-repellent organic compound pattern by utilizing a hydrolysis reaction of a silane halide. A method for manufacturing a solid-state imaging device having an on-chip color filter, comprising a step of repeating a step of forming a filter film and a step of removing the water-repellent organic compound by a desired number of colors.