JPH07161950A - Solid-state image pick-up device and its manufacture - Google Patents

Abstract

PURPOSE:To form a pattern of a specified size stably and to increase the light condensing performance of a photodetector section by decreasing the reflection from a shielding film. CONSTITUTION:A photodetector section 21 and a charge transfer channel 22 are formed on a substrate 20 and then a shielding film 23 is formed on the charge transfer channel 22 and a black filter layer 25 is formed on the shielding film 23. Nextly, a protective film 26 is formed on the photodetector section 21 and the black filter layer 25 and microlenses 28 are formed on the protective film 26. Due to this structure, exposed light in the exposure process is absorbed by the black filter layer 25 and the reflection from the shielding film 23 can be reduced. Since the microlenses 28 are formed on recessed section of the protective film 26 and there is a difference in a refractive index between parts on and under an interface between the protective film and the microlenses, the light condensing performance of the microlenses 28 is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device in which a plurality of light-receiving parts and charge transfer paths for transferring charges thereof are formed on a substrate, and microlenses are formed in the upper layers of the respective light-receiving parts, and this device. Manufacturing method.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing a manufacturing process of a solid-state image pickup device. As shown in FIG. 1A, a plurality of light receiving portions 2 are formed in the substrate 1, and a charge transfer path 3 for transferring charges obtained by photoelectric conversion of these light receiving portions 2 is provided in each light receiving portion 2. It is formed along the array. A flattening layer 4 is formed on the light receiving portion 2 and the charge transfer path 3. A light shielding film (not shown) is formed on each charge transfer path 3.

In the next step, a microlens resist 5 is applied on the flattening layer 4 as shown in FIG. 1B, and a mask 6 is placed after this, and the microlens resist 5 is exposed and developed by the same process. Patterning is performed as shown in (c) to form a microlens pattern 5a.

In the next step, the microlens pattern 5a is heat-treated as shown in FIG. 3D, whereby the microlens pattern 5a is thermally deformed into a spherical shape, and FIG. As shown in, each microlens 7 is formed on the upper layer of each light receiving portion 2. As a result, a solid-state imaging device is manufactured.

On the other hand, the solid-state image pickup device shown in FIG. 4 is manufactured in order to improve the light converging property on the light receiving portion. A light receiving portion 11 and a charge transfer path 12 are formed on the substrate 10. A protective film 13 is formed on the light receiving portion 11 and the charge transfer path 12, and the protective film 1 is formed.
A light shielding film 14 is formed on the surface 3.

Further, a flattening layer 15 is formed, and each color filter 16 is formed on the light receiving portion 11 in the flattening layer 15. These color filters 16 are the three primary colors R (red), G (green), B (blue), or the complementary colors Y (yellow), M (magenta), and C (cyan).

A first microlens 17 is formed on the flattening layer 15, and a second microlens 19 is formed on the flattening layer 18 with a flattening layer 18 interposed therebetween. Therefore, the light is condensed by the first and second microlenses 17 and 19 and enters each light receiving unit 11.

However, in both such manufacturing methods, ultraviolet light is irradiated through the mask 6 during the exposure process for forming the microlens pattern 5a, and this ultraviolet light is reflected by the light-shielding film on each charge transfer path 3. The extra-ultraviolet light, which is reflected and is larger than the normal exposure amount, is irradiated on the microlens resist 5.

Therefore, it becomes difficult to form the microlens pattern 5a having a predetermined size. For example, when the microlens 7 is formed of a positive type resist, the amount of exposure increases due to the reflected light from the light shielding film, a thin pattern is formed with a predetermined size, and a nonuniform pattern is formed due to the difference in reflection. The amount of light incident on the light receiving unit 2 varies and uneven sensitivity occurs.

Further, in the device in which the first and second microlenses 17 and 19 are formed to improve the light collecting property, the light receiving portion 11 and the second light receiving portion 11 are formed to form the respective flattening layers 15 and 18.
The film thickness between the micro lens 19 and the micro lens 19 becomes thicker.

Therefore, even though the first and second microlenses 17 and 19 are formed, these flattening layers 1 are formed.
As the thicknesses of 5 and 18 become thicker, the amount of shift of the focal position due to the oblique light with respect to the light receiving unit 11 increases, and the light-collecting property deteriorates.

[0012]

As described above, the microlens pattern 5 having a predetermined size is formed by the reflection on the light-shielding film.
It is difficult to form a, and the shift amount of the focal position due to the oblique light with respect to the light receiving unit 11 becomes large, so that the light collecting property is deteriorated.

Therefore, the present invention provides a solid-state image pickup device capable of forming a pattern of a predetermined size stably by reducing reflection on a light-shielding film, and further improving a light-collecting property on a light-receiving portion, and a manufacturing method of this device. The purpose is to

[0014]

According to a first aspect of the present invention, a light receiving portion and a charge transfer path for transferring charges obtained by photoelectric conversion of the light receiving portion are formed on a substrate, and light is shielded on the charge transfer path. In a solid-state imaging device having a film formed thereon, a light absorbing layer formed on a light shielding film, a light receiving portion and a protective film formed on the light absorbing layer so as to cover the light receiving portion and the light absorbing layer, and the protective film And a microlens formed in the upper layer of the light receiving portion of the solid-state image pickup device for achieving the above object.

According to a second aspect of the present invention, a solid-state image pickup in which a light receiving portion and a charge transfer path for transferring charges obtained by photoelectric conversion of the light receiving portion are formed on the substrate and a light shielding film is formed on the charge transfer path. In the method of manufacturing a device, a first step of forming a light absorbing layer on the light shielding film, and a second step of forming a protective film on the light receiving portion and the light absorbing layer so as to cover the light receiving portion and the light absorbing layer. And a third step of applying a resist for a microlens on the protective film, patterning the resist after this, and forming a microlens in the upper layer of the light receiving portion by a heat treatment, thereby achieving the above object. And a method for manufacturing a solid-state imaging device.

[0016]

The light receiving portion and the charge transfer path are formed on the substrate, the light shielding film is formed on the charge transfer path, and the light absorption layer is formed on the light shielding film. Then, since the protective film is formed on the light receiving portion and the light absorbing layer and the microlens is formed thereon, the exposure at the time of the exposure processing is absorbed by the light absorbing layer and the amount of reflection from the light shielding film can be reduced. . Also, the micro lens is
Since it is formed on the protective film, the light-converging property of the microlens is improved due to the difference in the refractive index.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a manufacturing process of a solid-state imaging device. As shown in FIG. 3A, a light receiving portion 21 is formed in each concave portion of the substrate 20, and a charge transfer path 22 is formed along the arrangement of these light receiving portions 21, and a light shielding film 23 is formed thereon. Has been done.

In the next step, a protective film 24 (shown in FIG. 2) made of SiN is formed on each light receiving portion 21 and the light shielding film 23 so as to cover the light receiving portion 21 and the light shielding film 23. A black filter layer 25 is formed on each of the light shielding films 23 on the 24.

The black filter layer 25 is formed by first protecting the protective film 2.
4 is coated with a film for a filter layer, formed by exposure, development and patterning, and then dyed with a black dyeing solution.

In the next step, these black filter layers 2
5 and the protective film 24, a protective film 26 is applied so as to cover the black filter layer 25 and the protective film 24, as shown in FIG. The protective film 26 is light-transmissive and is formed of, for example, an acrylic resist. The refractive index n2 of the protective film 26 is 1.55.

In the next step, on the protective film 26,
A microlens resist 27 is applied as shown in FIG. The microlens resist 27 is a positive resist, for example, a novolac-based resist or a styrene-based resist.

In the next step, although not shown, a mask is arranged, and patterning is performed by exposure and development processes as shown in FIG. 3D to form a microlens pattern 27a.

After that, the photosensitive resin is crosslinked by irradiation with ultraviolet rays to decolorize it. In the next step, heat treatment is performed on the microlens pattern 27a, which causes the microlens pattern 27a to be thermally deformed.
As shown in (e), each microlens 28 is formed on the upper layer of each light receiving portion 2. The refractive index n1 of these microlenses 28 is 1.65.

As a result, as shown in FIG. 2, the light receiving portion 21 and the charge transfer path 22 are formed on the substrate 20, the light shielding film 23 is formed on the charge transfer path 22, and the light shielding film 23 is further formed. A solid-state imaging device in which a black filter layer 25 is formed on the protective film 26, the protective film 26 is formed on the light receiving portion 21 and the black filter layer 25, and the microlenses 28 are formed on the protective film 26 on the light receiving portion 21. Is manufactured.

According to such a manufacturing method, ultraviolet light is absorbed by the black filter layer 25 during the exposure processing for forming the microlens pattern 27a, and patterning can be performed with a predetermined exposure amount.

As a result, the microlens pattern 2 is formed.
7a is not formed thinner than a predetermined size, the amount of light reflected from the light shielding film 23 is reduced, and a uniform microlens pattern 27a is formed without variations.

On the other hand, when the protective film 26 is applied as shown in FIG. 1 (b), the protective film 26 is formed on each light receiving portion 21.
Has a concave shape, and the microlenses 28 are formed on the upper layer. The refractive index n1 of the microlens 28 is 1.
65, the refractive index n2 of the protective film 26 is 1.55, and the relationship of n1> n2 is satisfied.

Therefore, as shown in FIG. 2, the optical path is refracted by the microlens 28 toward the central portion of the light receiving portion 21, and further refracted toward the central portion of the light receiving portion 21 at the boundary surface between the microlens 28 and the protective film 26. . As a result, the light collecting property for the light receiving unit 21 is improved.

Further, since the distance between the light receiving portion 21 and the microlens 28 is short, the shift of the focal position with respect to the oblique light is reduced, the factor of deterioration of the light collecting property is eliminated, and the light collecting property is improved.

The present invention is not limited to the above-mentioned embodiment, but may be modified within the scope of the invention. Although the black filter layer 25 is dyed with a black dyeing solution, a pigment dispersion type resist may be used.

[0031]

As described in detail above, according to the present invention, the reflection at the light shielding film can be reduced to form a pattern having a predetermined size in a stable manner, and further, the solid-state image pickup device which can improve the light collecting property for the light receiving portion. And the manufacturing method of this apparatus can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of a solid-state imaging device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of the solid-state imaging device.

FIG. 3 is a diagram showing a manufacturing process of a conventional device.

FIG. 4 is a block diagram of a conventional device.

[Explanation of symbols]

20 ... Substrate, 21 ... Light receiving part, 22 ... Charge transfer path, 23 ...
Light-shielding film, 24 ... Protective film, 25 ... Black filter layer, 26 ... Protective film, 27 ... Microlens resist, 27a ... Microlens pattern, 28 ... Microlens.

Claims (2)

[Claims] 1. A solid-state imaging device comprising a substrate, a light-receiving portion, and a charge transfer path for transferring charges obtained by photoelectric conversion of the light-receiving portion, and a light-shielding film formed on the charge transfer path. A light absorbing layer formed on the film; a protective film formed on the light receiving portion and the light absorbing layer so as to cover the light receiving portion and the light absorbing layer; formed on the light receiving portion on the protective film. A solid-state image pickup device comprising: 2. A method of manufacturing a solid-state image pickup device, comprising: a light receiving portion on a substrate; and a charge transfer path for transferring charges obtained by photoelectric conversion of the light receiving portion, and a light shielding film formed on the charge transfer path. A first step of forming a light absorbing layer on the light shielding film, and a second step of forming a protective film on the light receiving portion and the light absorbing layer so as to cover the light receiving portion and the light absorbing layer, A third step of applying a resist for a microlens on the protective film, patterning the resist after this, and forming a microlens in the upper layer of the light receiving portion by heat treatment, the third step. Manufacturing method.