JPH03297167A - Microlens - Google Patents

Abstract

PURPOSE:To remove an unnecessary flattened layer part such as a pad part by employing an inorganic material and an organic material for a microlens or employing an organic material for the flattened layer and an inorganic material for the microlens. CONSTITUTION:A transparent inorganic material silicon ladder polymer 3a is formed on a semiconductor substrate including an optical detector part and a transfer part into a thickness or more where a base stepped part can be absorbed. There are successively laminated a transparent thermoplastic resin layer 4a of a microlens (Ml) host material and a photoresist layer 5a for plasma etching. After the photoresist is patterned 5, pattern formation 4b of the Ml host material is performed by O2 plasma etching. Thereupon, the polymer 3a acts as a stopper, and after removal of the resist Ml formation 4 is performed by heat reflowing. Finally, after a photoresist 6 is formed and patterned, an unnecessary part is removed by etching, and the resist is removed to form the Ml. Hereby, the Ml can be formed with high accuracy and hence the unnecessary part such as a pad can be removed.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to improving the sensitivity of solid-state image sensors.
This relates to a microlens (microscopic condenser) placed in front of the photoelectric conversion section.

[Conventional technology]

FIG. 2 is a cross-sectional flow diagram showing the conventional microlens formation process disclosed in, for example, Japanese Unexamined Patent Publication No. 61-203663. In the figure, 1 is a photodiode section;
2 is a pad portion, 23 is a flattening layer, and 24 is a microlens.

Next, the formation flow will be explained.

A negative photosensitive transparent resin 1i23a is formed on a semiconductor substrate having a light receiving part and a transfer part by a spin coating method.
(a), the layer on the photodiode 2 is insolubilized by exposure and development, and the pad portion 2. Unnecessary parts such as dicing lines are removed (FIG. 2(b)).

By repeating this process, the steps on the semiconductor surface are flattened,
A planarization layer 23 is formed (FIG. 2(C)). Subsequently, a photosensitive heat-softening transparent resin layer 24a, which is a microlens base material, is formed by spin coating as shown in FIG. 2(d).
), exposure and development to remove the resin layer other than the photodiode portion (FIG. 2(e)).

Finally, the microlens 24 is formed by heat flow (
Figure 2(f)).

[Problem to be solved by the invention]

Conventional microlenses are formed as described above, and since microlenses are formed after removing unnecessary parts such as the pad portion of the flattening layer, coating unevenness occurs in the formation of the resin layer of the microlens base material. This occurs, making it impossible to form microlenses with high precision.

Furthermore, because the etching selectivity cannot be maintained between the flattening layer and the microlens base material in the conventional method, techniques such as etching cannot be used to form microlenses, and the range of selection of the microlens base material is limited. was there.

This invention was made in order to solve the above-mentioned problems, and the purpose is to obtain a microlens that can use techniques such as etching when forming a microlens pattern and can form lenses with high precision. do.

[Means to solve the problem]

The microlens according to the present invention uses a material that is selective to etching for the flattening layer and the microlens. Specifically, it uses an inorganic material for the flattening layer and an organic material for the microlens. Alternatively, an organic material is used for the flattening layer and an inorganic material is used for the microlens.

[Effect]

The flattening layer and microlens base material in the present invention allow the flattening layer to act as a stopper during microlens pattern formation, and unnecessary flattening layer portions such as pad portions can be removed after microlens formation.

〔Example〕

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

FIG. 1 is a cross-sectional flow diagram showing a process for forming a microlens according to an embodiment of the present invention. In the figure, 3 is a flattening layer, 4 is a microlens, and 5°6 is a resist.

Next, the formation flow of this embodiment will be explained.

A transparent inorganic material such as silicon ladder polymer 3a such as OCD (manufactured by Tokyo Ohka Chemical Co., Ltd.) or polyvinyl silsesquiotisane (PVSQ) is placed on the semiconductor substrate that has the light receiving part and the transfer part to a thickness that is thicker than that which can absorb the level difference in the base. It is formed using a spin coating method. Next, a transparent thermoplastic resin layer (for example, PMMA, PGMA, P
MIPK etc.) 4a, photoresist layer for plasma etching (for example, Tokyo Ohka ■○FPR-800, TSMR-
8900 etc.) 5a (FIG. 1(a)).

After the photoresist is patterned 5, a pattern 4b of the microlens base material is formed by 0° plasma etching (FIG. 1B)). At this time, the flattening layer 3a made of silicon ladder polymer has a thickness of 0. Acts as a stopper against plasma etching. After removing the photoresist with a stripping solution (ethanol, acetone, etc.), microlens formation 4 is performed using a hot flow (FIG. 1(C)).

Finally, the flattening layer 3 for pads, dicing lines 2, etc.
a To remove unnecessary parts, after laminating and patterning the photoresist 6 (Fig. 1 (d)), remove the unnecessary parts by etching with a solvent such as Ansor in the case of PVSQ (hydrofluoric acid, etc. in the case of OCD). Then, remove the resist with ethanol or the like to form a microlens (Fig. 1(e)).
.

In this way, according to this example, inorganic and organic materials that are selective to etching are used as the flattening layer and the microlens base material, so etching can be performed using the flattening layer as a stopper. It is possible to form microlens patterns with high precision using
This has the effect that a material with excellent transmission characteristics can be selected, and unnecessary parts such as pads can be removed after the microlens layer is formed.

In the above example, unnecessary parts are removed after heat flow for forming microlenses, but after removing unnecessary parts,
Finally, a heat flow may be performed to form microlenses.

Further, the microlens forming step may utilize isotropic etching, etc., and the same effects as in the above embodiments can be achieved.

Further, the material of the flattening layer and the material of the microlens base material in the above embodiment may be replaced, and the same effects as in the above embodiment can be obtained.

[Effects of the Invention] As described above, according to the present invention, materials that are selective to etching are used as the flattening layer and the microlens base material, so the flattening layer can be used as a stopper. There is an effect that a microlens pattern can be formed with high precision using etching.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional flow diagram showing the process of forming a microlens according to an embodiment of the present invention, and FIG. 2 is a cross-sectional flow diagram showing the process of forming a conventional microlens. In the figure, 3 is a flattening layer and 4 is a microlens. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In a microlens formed on a flattening layer that flattens steps on a semiconductor substrate having a light receiving section and a signal transfer section, the flattening layer and the microlens base material are made of a material that is selective to etching. A microlens characterized by using.