JPH0529590A - Method of manufacturing solid-state image sensor - Google Patents

Abstract

(57) [Summary] (Modified) [Objective] The present invention is intended to form a microlens conforming to the shape of the opening of the photodiode without lengthening the manufacturing process. [Structure] A resist made of heat-deformable resin is applied on an image sensor substrate in a patterning process, a pattern corresponding to the shape of the image sensor is formed by an exposure process, and the resist is irradiated with light rays in the next light-transmitting process. This resist is used as a light-transmissive resist 22, and in the next curing step, the light-transmissive resist 22 is cured by being irradiated with predetermined light through a mask 21 in which holes corresponding to the shape of the image sensor are formed. In the heating step, the translucent resist is heated and the portion other than the cured portion is curved. In addition, after the light-transmitting step, the step moves to a deforming step, and in this step, the light-transmissive resist 22 is subjected to ultraviolet ray hearting treatment to deform the light-transmissive resist.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid-state image pickup device for manufacturing a microlens.

[0002]

2. Description of the Related Art In a method of manufacturing such a microlens, for example, as a first technique, Japanese Patent Application Laid-Open No. 2-89687,
As a technique, there is one disclosed in Japanese Patent Laid-Open No. 64-10666. A manufacturing process diagram of the first technology is shown in FIG. A plurality of photodiodes 2 are formed in an array on the semiconductor substrate 1 as shown in FIG.
The transfer path 3 is formed between them, the shield film 4 is formed on the transfer path 3, and the color filter layer 5 is formed on the shielding film 4. First, as shown in FIG. 3B, a positive resist 7 is applied on the surface of the color filter layer 5 and patterned according to the arrangement position of each photodiode 2. Next same figure
As shown in (c), the positive resist 7 becomes a resist 8 which is made transparent by irradiation of a predetermined light, and then the resist 8 is heated to become a microlens 9.

FIG. 7 is a manufacturing process diagram of the second technique. Same figure
As shown in (b), a transparent resist 10 is applied on the surface of the color filter layer 5, and then a positive resist 7 is applied on the upper surface thereof as shown in (c) of FIG. Patterning is performed according to the arrangement position. Next same figure
As shown in (d), the positive type resist 7 is heated to be transformed into a lens-shaped resist 11, and then a pattern is transferred by a reactive sputter etching (RIE) process. The microlens 12 shown is formed.
Then, the light is focused on each photodiode 2 by these microlenses 9 and 12, which leads to the high sensitivity of the image pickup device. As another technique, microlenses are formed in two layers 13 and 14 as shown in FIG.

By the way, since the photodiode 2 is formed with the transfer paths 3 as shown in FIG. 9, it has a vertically long shape along these transfer paths 3. The cross-sectional shape of the microlenses manufactured by the first and second techniques is determined by the thickness and width of the positive resist 7. The lens patterns of these microlenses are formed in the X direction (hereinafter referred to as the lateral direction) with respect to the photodiode 2 in the Y direction (hereinafter referred to as the longitudinal direction) as shown in FIGS.

Therefore, the lens pattern of the microlens is formed according to the length of one side of the opening of the photodiode 2, and the film thickness and width of the resist 7 are determined according to the shape of this opening. For example, microlenses 9 and 12
When the lens pattern of is matched with the length of one side of the photodiode 2 viewed from the horizontal direction shown in FIG. 10, the curvature of the microlenses 9 and 12 becomes large in the vertical direction as shown in FIG. It comes off from the diode 2.
On the contrary, if the lens pattern is adjusted to the length of one side of the photodiode 2 viewed from the vertical direction shown in FIG. 12, the light converging property in the horizontal direction is poor as shown in FIG. Therefore, it is difficult to form the lens patterns of the microlenses 9 and 12 according to the shape of the opening of the photodiode 2.

Further, the two-layer microlens 1 shown in FIG.
In Nos. 3 and 14, the light condensing property for the photodiode 2 is good, but the microlens must be formed twice,
The manufacturing process becomes long.

[0007]

As described above, it is difficult to form a microlens matching the shape of the opening of the photodiode, and even if the lens can be formed, the manufacturing process is long.

Therefore, an object of the present invention is to provide a method of manufacturing a solid-state image pickup device which can form a microlens conforming to the shape of an opening of a photodiode without lengthening the manufacturing process.

[0009]

The present invention provides a method of manufacturing a solid-state image pickup device, wherein a microlens is formed in a portion corresponding to the image pickup device on a substrate on which an image pickup device is formed and a filter layer is formed on the substrate. A patterning process in which a resist made of a heat-deformable resin is applied on the resist, and the heat-deformable resin is patterned by an exposure process according to the shape of an image sensor, and the resist is irradiated with light rays to make the resist a translucent resist. A light-transmitting step, a curing step of irradiating the light-transmissive resist with predetermined light through a mask in which holes corresponding to the shape of the image sensor are formed on the light-transmissive resist to cure the light-irradiated portion. It is a method for manufacturing a solid-state image pickup device, which aims to achieve the above object from a heating step of heating a translucent resist to curve the portion other than a cured portion.

Further, the present invention is a method for manufacturing a solid-state image pickup device in which a microlens is formed in a portion corresponding to the image pickup device on a substrate on which an image pickup device is formed and a filter layer is formed on the image pickup device, and a heat-deformable resin is formed on the substrate. A patterning step of applying a resist consisting of, and patterning the heat-deformable resin according to the shape of the image sensor by an exposure process; and a light-transmitting step of irradiating the resist with light rays to make this resist a light-transmissive resist. A method for manufacturing a solid-state image pickup device, which aims to achieve the above object from a deforming step of deforming the transparent resist by subjecting the transparent resist to ultraviolet hardening treatment.

[0011]

By providing such means, a resist made of a heat-deformable resin is applied on the image pickup device substrate in the patterning process, and a pattern corresponding to the shape of the image pickup device is formed by the exposure process. In the curing step, the resist is irradiated with light rays to make it a translucent resist, and in the next curing step, the translucent resist is irradiated with predetermined light through a mask in which holes corresponding to the shape of the image sensor are formed. Then, in the next heating step, the translucent resist is heated to curve other than the cured portion.

Further, by providing the above means, a resist made of a heat-deformable resin is applied on the image pickup device substrate in the patterning process, and a pattern corresponding to the shape of the image pickup device is formed by the exposure process, and the next light transmission is performed. In the curing step, the resist is irradiated with light rays to make this resist a light-transmissive resist, and in the next deformation step, the light-transmissive resist is deformed by an ultraviolet hardening treatment for the light-transmissive resist.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. The same parts as those in FIGS. 6 and 7 are designated by the same reference numerals, and detailed description thereof will be omitted.

1 and 2 are manufacturing process diagrams of the microlens manufacturing method. FIG. 1 is a manufacturing process diagram of the microlens viewed from the lateral direction, and FIG. 2 is a manufacturing process diagram of the same lens viewed from the vertical direction. Is. In the figure, the semiconductor substrate 1 and the like which are the lower layers of the color filter layer 5 are omitted.

First, as shown in FIGS. 1 and 2A, a positive resist 20 made of a heat-deformable resin is applied on the surface of the color filter layer 5 in the patterning process. The positive resist 20 is made of styrene and novolac and is deformed by heating. Next, a mask 21 corresponding to the shape of the photodiode 2 is arranged.
The mask 21 is arranged at a pitch according to the arrangement interval of the photodiodes 2. Next, an exposure process is performed through this mask 21, and this process forms a positive resist 20 in a pattern corresponding to the shape of the photodiode 2 as shown in FIG.

Next, in the light-transmitting step, the positive type resist 2 is used.
UV light is irradiated to 0. As a result, the photosensitive component of the positive resist 20 is decomposed, and the positive resist 20 becomes a colorless and transparent light-transmitting resist 22.

In the next curing step, a mask 23 is arranged on the translucent resist 22 as shown in FIG. This mask 23 has holes 24 formed as shown in FIG. The lateral dimension of the hole 24 is formed to be about 1.0 to 2.0 μm, which is shorter than the lateral width of the photodiode 2.
The lateral dimension is formed as narrow as possible. Next, UV light is irradiated through the mask 23. This UV
The optimum wavelength of light is 300 nm or less on the short wavelength side. By this irradiation of UV light, the surface portion A of the translucent resist 22 irradiated with UV light is cured. And the mask 23
Is moved to another position.

In the next heating step, the translucent resist 22
Is heated to a temperature of 150 to 160 ° C., and by this heating, the parts other than the cured part A are deformed and curved. Thus, the micro lens 25 is formed.

FIG. 4 shows a cross-sectional shape of the microlens 25 as viewed from the lateral direction, and FIG. 5 shows a cross-sectional shape of the microlens 25 as viewed from the vertical direction. As can be seen from the figure, the light is condensed so that it is uniform in the lateral direction of the photodiode 2 and concentrated in one point in the longitudinal direction.

As described above, in the first embodiment described above, the photodiode 20 is applied by applying the resist 20 and exposing it.
A pattern corresponding to the shape of the photo resist 2 is formed by irradiating the resist 20 with a light beam to form a translucent resist 22, and then a hole 24 corresponding to the shape of the photodiode 2 is formed in the translucent resist 22. UV light is radiated through the mask 23 to cure, and then the translucent resist 22 is heated to cure part A.
Since the other components are modified, the microlens 25 having a cross-sectional shape that matches the shape of the opening of the photodiode 2 can be formed, and the light-collecting properties in the horizontal and vertical directions can be improved. Further, by changing the pattern size of the hole 24 of the mask 23, the microlens 25 having an arbitrary shape, that is, an arbitrary curvature can be formed. Furthermore, the microlens 25 having a good light-collecting property can be formed by a small number of steps. Next, a second embodiment of the present invention will be described.

In this embodiment, the curing process and the heating process in the above-mentioned one embodiment are replaced with a deformation process. In this deforming step, the entire surface of the translucent resist 22 is subjected to ultraviolet hardening treatment for irradiating UV light to deform the translucent resist 22, and the shape of the microlens 25 is controlled by the irradiation amount of UV light. can do. That is, if the irradiation amount of UV light is reduced, the microlens 25
Is formed in a spherical shape, and if the irradiation amount is increased, the shape of the microlens 25 is formed in an aspherical shape such as a square shape.

By such a deforming step, a spherical microlens having an arbitrary curvature can be formed, and further, an aspherical microlens such as not only a spherical surface but also a square shape can be formed.

The present invention is not limited to the above-mentioned one embodiment, and may be modified within the scope of the invention. For example, the wavelength range of UV light is not limited. Further, the microlenses may be transparent and colored instead of being colorless and transparent.

[0024]

As described above in detail, according to the present invention, it is possible to provide a microlens manufacturing method capable of forming a microlens conforming to the shape of the opening of a photodiode without lengthening the manufacturing process.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram when an embodiment of a microlens manufacturing method according to the present invention is viewed from the lateral direction.

FIG. 2 is a manufacturing process diagram when an embodiment of the same method is viewed from the vertical direction.

FIG. 3 is a configuration diagram of a mask used in the method.

FIG. 4 is a diagram showing a condensed state of a microlens formed by the same method.

FIG. 5 is a diagram showing a condensed state of a microlens formed by the same method.

FIG. 6 is a manufacturing process diagram of a conventional microlens manufacturing method.

FIG. 7 is a manufacturing process diagram of a conventional microlens manufacturing method.

FIG. 8 is a configuration diagram of a conventional two-layer microlens.

FIG. 9 is a diagram showing an arrangement state of photodiodes.

FIG. 10 is a diagram showing a condensed state of a conventional microlens.

FIG. 11 is a diagram showing a condensed state of a conventional microlens.

FIG. 12 is a diagram showing a condensed state of a conventional microlens.

FIG. 13 is a diagram showing a condensed state of a conventional microlens.

[Explanation of symbols]

1 ... Semiconductor substrate, 2 ... Photodiode, 3 ... Transfer path,
4 ... Shielding layer, 5 ... Color filter layer, 20 ... Positive resist, 21 ... Mask, 22 ... Translucent resist, 23 ... Mask, 24 ... Hole, 25 ... Microlens.

Claims (2)

[Claims] 1. A method for manufacturing a solid-state image sensor, comprising forming an image sensor and forming a microlens at a portion corresponding to the image sensor on a substrate having at least a filter layer formed on the image sensor. And a patterning step of patterning the heat-deformable resin according to the shape of the image pickup device by an exposure process, and light-transmitting the resist as a light-transmissive resist by irradiating the resist with light rays. A step of irradiating the light-transmissive resist with a predetermined light through a mask in which holes corresponding to the shape of the image sensor with respect to the light-transmissive resist, and curing the light-irradiated portion; And a heating step of heating the translucent resist to curve the portions other than the cured portion. 2. A method of manufacturing a solid-state image sensor, comprising forming an image sensor and forming a microlens at a portion corresponding to the image sensor on a substrate on which at least a filter layer is formed. And a patterning step of patterning the heat-deformable resin according to the shape of the image pickup device by an exposure process, and light-transmitting the resist by irradiating the resist with light rays. A method of manufacturing a solid-state imaging device, comprising: a step of deforming the transparent resist by subjecting the transparent resist to ultraviolet hardening treatment.