JPH04184970A - Formation method for microlens - Google Patents

Abstract

PURPOSE:To obtain lenses, which are high in heat stability and have a high condensing capacity, by a method wherein an ion implantation of Si is performed in microlenses formed of a thermoplastic resin and the microlenses are made to crosslink and are made to insolubilize. CONSTITUTION:A film 9a consisting of a thermoplastic resin is formed on a semiconductor substrate 10 having photodetecting parts, transfer and the like by a spin coating method. Then, end parts 9b microlens formation parts are removed by an etching or like on an aluminium light-shielding film 8 of each photodetecting part. Then, the microlens formation parts are heated and are made to reflow and microlenses 9 are formed. Lastly, an ion implantation 11 of Si is performed and the lenses 9 are made to crosslink and are made to insolubilize. Thereby, highly reliable lenses, which are stable to heat and a solvent and have a high condensing capacity, can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to improving the sensitivity of solid-state imaging devices [Prior Art]
1 is a cross-sectional flow diagram showing a conventional method for forming a microlens as shown in the above publication. In the figure, 1 is a silicon substrate, 2 is a photodiode, 3 is a channel stop, 4 is a transfer section, and 5 and 7 are An insulating layer, 6 a polysilicon gate, 8 an aluminum light-shielding film, 9 a microlens, and IO a semiconductor substrate having a light receiving section and a signal transfer section.

Next, the formation method will be explained.

A film made of a heat-softening transparent material 9a is formed on a semiconductor substrate 10 having a light receiving section, a transfer section, etc. by spin coating or the like (FIG. 3(a)). Next, on the aluminum light-shielding film 8 between each light-receiving part, the ends of the microlens forming parts are removed by etching (see Fig. 3) The microlenses formed by this method can easily obtain a high curvature; Has high light gathering ability.

[Problem to be solved by the invention]

In the conventional method for forming microlenses, as described above, the microlenses are formed by being softened by heat, so they lack thermal stability and have problems such as deformation during heat treatment steps such as assembly in subsequent steps.

This invention was made to solve the above-mentioned problems, and aims to provide a method for forming a microlens that has high thermal stability and high light-gathering ability.

[Means to solve the problem]

In the method for forming a microlens according to the present invention, Si ions are implanted into a microlens made of a thermoplastic resin, and the microlens is crosslinked and made insolubilized.

[Effect]

In this invention, the microlens is formed by crosslinking and insolubilizing the thermoplastic resin, so that it is stable against heat and hot materials, has high reliability, and has high light gathering ability.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

1A to 1C are cross-sectional flow diagrams showing a method for forming a microlens according to an embodiment of the present invention, and the same reference numerals as in FIG. 3 indicate the same or corresponding parts. Also, Figure 1 (C
Arrow 11 in J indicates Si ion implantation.

Next, the formation method will be explained.

As shown in FIG. 1(a), for example, a
A film 9a made of a thermoplastic translucent resin such as FPR-800 or 0DOR-1013 is formed by spin coating or the like. Next, as shown in FIG. 1(b), the end portions of the microlens forming portions are removed by etching or the like on the aluminum light shielding film 8 between the light receiving portions.

Further heat, e.g. 150℃ for 0FPR-800.
The microlens 9 is formed by heating the front and back and causing it to flow. Finally, as shown in FIG. 1C, Si ions are implanted to crosslink the microlenses 9 and make them insoluble.

FIG. 2 shows the crosslinking mechanism when Si is injected into the phenolic resin. For example, when Si is injected into a phenolic resin as shown in FIG. 2(a), -OH, -CH, and -CH of the phenolic resin.

H is eliminated and cross-linked, for example, as shown in FIG. 2 (bJ).

In this example, a film made of thermoplastic translucent resin is formed by spin coating on a semiconductor substrate lO having a light receiving part, a transfer part, etc., and the ends are removed by etching etc. to form a microlens. By further heating and flowing Si ions into the forming area, the transparent resin layer of the microlens takes on a three-dimensional network structure, improving heat resistance and creating a thermally stable microlens. It has the effect of forming a lens.

Next, other embodiments of the present invention will be described.

In the above example, after the etching process, the etching process was performed at 150°C for 30 minutes.
Although the microlens 9 was cross-linked by heating at a temperature of .degree. C. and finally implanting Si ions to crosslink the microlens 9, Si implantation may be performed prior to heat flow. In this case, since the degree of crosslinking is low, the rate of thermal stabilization is lower than in the above example, but if the heat flow temperature for forming microlenses is set to 170°C for 30 minutes,
During heat treatment in assembly, etc., which is a post-process (heat treatment temperature 1
50 to 160[deg.] C.), it is possible to obtain a microlens with high thermal stability and high light-gathering ability, similar to the above embodiments.

〔Effect of the invention〕

As described above, according to the present invention, Si is injected into the heat-flowed thermoplastic resin to make it cross-linked and insolubilized, resulting in a highly reliable product that is stable against heat and hot materials and has a high light-gathering ability. microlenses can be formed.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional flow diagram showing a method for forming a microlens according to an embodiment of the present invention, FIG. 2 is a diagram showing the crosslinking mechanism of the present invention, and FIG. 3 is a diagram showing a method for forming a microlens according to a conventional example. FIG. In the figure, 9 indicates a microlens, 10 indicates a semiconductor substrate having a light receiving section and a signal transfer section, and 11 indicates Si implantation. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A step of forming a microlens using a thermoplastic resin as a base material on each light receiving section on a semiconductor substrate having a light receiving section and a signal transfer section, and injecting Si into the microlens. 1. A method for forming a microlens, comprising the step of crosslinking a base material.