JPH04275459A - Solid-state image pickup device and for manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce the reflectance from 5-10% to about 1-5%, by forming an antireflective film with a given thickness over a microlens surface uniformly. CONSTITUTION:An antireflective film 6 is formed by laminating the surface of a microlens 1 with a monomolecular layer, which is made of a solution of any of fluorine-contained epoxy resin, acrylic resin, polyester resin, methacrylate resin, or phenol aldehyde resin in an ethereal or ketonic solvent in which hydrogen atoms have been substituted by fluorine atoms, in the Langmuir-blodgett's method or the water surface cast method.

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 having microlenses on each light-receiving section, and a method for manufacturing the same.

0002

2. Description of the Related Art FIG. 3 shows the structure of a conventional CCD solid-state image sensor having a microlens. 1 is a microlens,
2 is a photodiode, 3 is a silicon substrate, 4 is a vertical CC
D section, 5 is a polysilicon electrode, 7 is a silicon oxide film, 8
1 is a flattening film, and 10 is an air or inert gas layer.

The microlens 1 is formed for the purpose of increasing the amount of light incident on the photodiode 2 and increasing the sensitivity. The material constituting this microlens 1 is a transparent resin, such as acrylic resin or polystyrene. The reflectance of the surface of the transparent resin is about 5 to 10%. However, no antireflection film is formed on the surface of this microlens.

0004

[Problems to be Solved by the Invention] In recent years, the sensitivity of CCD solid-state imaging devices has improved significantly, and devices that are superior to the human eye are now being manufactured. If we can establish a technology to form an anti-reflection film on the surface of microlenses,
Furthermore, the sensitivity will be improved, expanding its use for safety purposes such as at night.

However, a film with a thickness of about 0.1 to 0.2 μm can be formed into a film with a vertical and horizontal width of 5 μm to 10 μm and a thickness of 2 μm as shown in FIG.
Conventionally, there has been no technology for forming microscopic convex lenses on the surface of microscopic convex lenses with a diameter of about m to 4 μm. For example, when a commonly used spin coating method is used to form a polymer resin film on the surface of a semiconductor element, uneven coating occurs due to the convex portions of microlenses.

SUMMARY OF THE INVENTION An object of the present invention is to provide a solid-state imaging device having an antireflection film of uniform thickness on the surface of a microlens, and a method for manufacturing the same.

[0007]

[Means for Solving the Problems] A solid-state imaging device according to the present invention as set forth in claim 1 is characterized in that an antireflection film having a uniform thickness is provided on the surface of a microlens.

[0008] Furthermore, the method for manufacturing a solid-state image sensing device according to the present invention as set forth in claim 2 provides a method for manufacturing a solid-state imaging device using hydrogen contained in an ether molecule or a ketone molecule in which a fluorine-containing epoxy resin, polyester resin, methacrylic resin, or phenol resin is dissolved. The method is characterized in that a monomolecular film of a solvent in which atoms are replaced with fluorine atoms is laminated on the surface of a microlens to form an antireflection film.

[0009]

[Operation] By using the present invention as set forth in claim 1 above, it is possible to reduce the reflectance of light incident on the microlens.

Furthermore, by using the present invention as set forth in claim 2 above, it is possible to form an antireflection film of a desired thickness and a uniform thickness on the surface of a microlens.

[0011]

EXAMPLES The present invention will be explained in detail below based on examples.

FIG. 1 shows a configuration diagram of a solid-state imaging device according to the present invention. 1 is a microlens, 2 is a photodiode, 3 is a silicon substrate, 4 is a vertical CCD section, 5 is a polysilicon electrode, 6 is an antireflection film, 7 is a silicon oxide film, 8 is a flattening film, 10 is air or inert It is a gas layer. As shown in FIG. 1, the microlens 1 of the solid-state imaging device of the present invention has an antireflection film 6 formed on the surface thereof with a uniform thickness. The material of this anti-reflection film 6 includes:
Acrylic resin, polyester resin, methacrylic resin, or phenol resin containing fluorine (hereinafter referred to as "fluorine-containing resin") is used.

Next, the manufacturing method according to claim 2 will be described. First, a fluorine-containing resin is dissolved in a predetermined solvent. What can be used as a solvent is an ether or a ketone in which the hydrogen atom is replaced with a fluorine atom. The ratio of fluorine-containing resin is 10% or less, preferably 5%.
% or less. This is because if it exceeds 10%, the viscosity of the fluororesin increases, making it difficult to form a monomolecular film and a thin film.

Next, using the Langmuir-Blodgett method (hereinafter referred to as the "LB method") or the water surface casting method, the monomolecular film 9 of the fluororesin described above is laminated on the surface of the microlens 1 to form an antireflection film 6. do. Figure 2 shows the principle of the LB method.

In the present invention, the LB method is mainly carried out when using a highly volatile solvent with a small number of molecules. LB
When performing this method, the above fluorine-containing resin solution is dropped onto the water surface. After dropping, most of the highly volatile solution evaporates, leaving behind the fluorine-containing resin. Sufficient surface pressure is applied to the monomolecular film on the water surface to maintain the state of the solid film 9 (FIG. 2(a)). Next, as shown in FIGS. 2(b) to 2(d), the wafer or chip is moved up and down in a direction across the monomolecular film 9. A monomolecular film is accumulated on the surface of the microlens 1 until a desired film thickness is obtained. Thereafter, if necessary, baking is performed to remove solvent molecules from the monomolecular film laminate to improve adhesion to the microlens 1. As a result, an antireflection film made of a fluorine-containing resin and having a uniform thickness is formed.

Next, when performing a water surface casting method, a thin film with a thickness of several 100 Å can be obtained by dropping several drops of the fluororesin solution onto the water surface using a dropper or the like. Next, if necessary, by discharging in an oxygen atmosphere, the surface of the microlens 1 is oxidized to make it hydrophilic and increase adsorption. After that, similarly to the LB method, the monomolecular film can be laminated on the surface of the microlens 1 by moving the wafer or chip up and down, or the wafer or chip can be held horizontally and brought as close to the water surface as possible, and then tilted slightly. The monomolecular film is attached onto the microlens 1 by contacting the thin film from one end. Thereafter, baking is performed in the same manner as in the LB method to improve adhesion to the microlens 1.

The applicable range of the thickness of the antireflection film formed as described above varies depending on the refractive index of the microlens, the refractive index of the fluorine-containing resin, the thickness of the microlens, and the wavelength of the incident light. Although it comes, it is 0.05 to 0.5 μm.
It will be about.

The present invention is characterized in that an antireflection film is provided on the microlens in a solid-state image sensor, but it can also be implemented in a liquid crystal display (LCD).

[0019]

As described above in detail, by using the solid-state image sensor of the present invention as set forth in claim 1, the sensitivity of the solid-state image sensor can be increased from about 5 to Improve by 10%. Incidentally, the surface reflectance is 5 to 10% in conventional solid-state image sensors, whereas
In the solid-state image sensor of the present invention, the reduction was about 1 to 5%. Furthermore, by using the method for manufacturing a solid-state image sensor according to the second aspect, it is possible to form a desired antireflection film evenly and with a uniform thickness on the surface of the microlens.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the structure of a solid-state image sensor according to the present invention.

FIG. 2 is a diagram showing the principle of the LB method.

FIG. 3 is a structural cross-sectional view of a conventional solid-state image sensor.

[Explanation of symbols]

1 Micro lens 2 Photodiode 3 Silicon substrate 4 Vertical CCD section 5 Polysilicon electrode 6. Anti-reflection film 7 Silicon oxide film 8 Planarization film 9 Monolayer 10　Air or inert gas layer

Claims (2)

[Claims] Claim 1: A solid-state imaging device having microlenses on each light receiving part, characterized in that an antireflection film made of a fluorine-containing resin film of a predetermined thickness is formed on the microlenses. Solid-state image sensor. Claim 2: A monomolecular film of a solution in which a fluorine-containing resin is dissolved in a solvent in which hydrogen atoms in ether or ketone are replaced with fluorine atoms in a solid-state imaging device having microlenses on each light receiving part. 2. The solid-state imaging device according to claim 1, wherein the solid-state imaging device is laminated on a microlens by an LB method or a water surface casting method, and an antireflection film made of a fluorine-containing resin film having a predetermined thickness is formed on the microlens. Method of manufacturing elements.