JPH069229B2 - Method of manufacturing solid-state imaging device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to improving the sensitivity of a solid-state image pickup device, and in particular, forming a lens array on the solid-state image pickup device to collect incident light on a photoelectric conversion unit. To improve photoelectric sensitivity,
The present invention relates to a method for manufacturing a lens array.

(Prior Art and Problems Thereof) In general, a solid-state imaging device has a photoelectric conversion unit and a signal reading unit on a semiconductor substrate, so that the effective photoelectric conversion region is limited to 30 to 50% of the entire area. As a means for solving this drawback, a method has been proposed in which a transparent lens is arranged on a solid-state image pickup device to collect incident light on a photoelectric conversion section (Japanese Patent Application No. 56-10399).

However, such a conventional proposal does not have a feasible method for forming a lens array.

Specifically, the method of forming the convex lens array on the solid-state imaging device is described in “A High Photosensitivity” by the present inventor.
IL-CCD Image Sensor with Monolithic Resin Lens Ar
Proceedings of the IEEE Internati-ona
l Electron Devices Meeting, pp.497-500, Decembe
r 1983. Was announced at. In this, a transparent photosensitive resin pattern is formed correspondingly on the photoelectric conversion element, and then heat treatment is performed at a temperature equal to or higher than the softening temperature of the photosensitive resin. The photosensitive resin pattern can be heat-fluidized to form a convex lens-shaped cross-sectional shape. However, the formation of the convex lens array utilizing the heat flow of the resin is unstable due to the large influence of the interface between the photosensitive resin and the base.

(Object of the Invention) The present invention eliminates the above-mentioned drawbacks and provides a method for manufacturing a convex lens array integrated on a solid-state imaging device.

(Structure of the Invention) In the solid-state imaging device according to the present invention, a photoelectric conversion element group formed in a mosaic pattern on a semiconductor substrate and a unit for reading out a signal photoelectrically converted by the photoelectric conversion element group are formed. The main surface of the solid-state imaging device is coated with a hydrophobic transparent resin layer, then the hydrophobic transparent resin layer is coated with a hydrophilic resin layer, and then the hydrophobic resin layer in a portion corresponding to the photoelectric conversion element group is removed. Then, a method for manufacturing a solid-state imaging device is obtained, in which a transparent dye is dyed by thermal transfer dyeing in the opening of the hydrophilic resin layer to form a convex lens array corresponding to the photoelectric conversion element group.

First Embodiment Next, the present invention will be described with reference to the drawings. 1 to 5 are views for explaining one embodiment of the method for manufacturing a solid-state image pickup device according to the present invention, and are conceptual sectional views of the solid-state image pickup device in the main steps.

FIG. 1 schematically shows a cross section of an interline transfer type CCD image pickup device, and a photoelectric conversion region 11 made of, for example, a photodiode is arranged on the main surface of a semiconductor substrate 10. Reference numeral 12 denotes a vertical CCD register area for reading out a signal photoelectrically converted in the photoelectric conversion area 11. Between the photoelectric conversion area 11 and the vertical CCD register 12, a transfer gate (not shown) for controlling transfer of signal charges is arranged. ing. Further, the vertical CCD register and the transfer gate region are shielded by a light-impermeable layer 13 such as aluminum. Transfer electrodes are arranged on the main surfaces of the vertical CCD register 12 and the transfer gate region via an insulator, but they are not shown because they are not related to the operation of the present invention.

In FIG. 2, after the CCD image pickup device is formed on the main surface 10 of the semiconductor substrate, a hydrophobic resin layer 14 such as novolac resin or polyether sulfone is coated. Thereafter, the bonding pad of the image pickup device and the resin layer 14 on the scribe line are removed by using a photolithography technique.

Next, as shown in FIG. 3, a resin layer 15 is coated on the resin layer 14 by mixing a hydrophilic resin such as casein, gelatin, pullulan, or polyvinyl alcohol with potassium dichromate as a photosensitizer. Then photoelectric conversion area
The hydrophilic resin layer 15 of the portion 16 corresponding to 11 is removed by a photochemical reaction. For example, when there is a vertical CCD register or a signal readout line between the vertical rows of the photoelectric conversion regions as in the case of the interline transfer CCD or MOS type image pickup device, the opening portion 16 of the hydrophilic resin layer shown in FIG. May have a stripe shape corresponding to the vertically arranged photoelectric conversion regions.

After forming the pattern of the hydrophilic resin 15 on the hydrophobic resin 14, a transparent hydrophobic dye 17 such as Whitex ERN (manufactured by Sumitomo Chemical Co., Ltd.) is subjected to thermal transfer dyeing as shown in FIG. The hydrophobic dye 17 is dyed on the hydrophobic resin 14 in the opening 16 using the hydrophilic resin 15 as a mask.

FIG. 5 shows a sectional shape after the transparent dye 17 is dyed. The hydrophobic resin layer in the portion dyed with the dye 17 has a convex cross-sectional shape due to volume expansion.

The dye also spreads laterally below the hydrophilic resin layer 15 acting as a mask for dyeing, and a continuous convex lens array can be formed. Finally, the hydrophilic resin layer 15 is removed.

The curvature of the convex lens can be determined by the width of the opening of the hydrophilic resin 15 and the temperature of thermal transfer dyeing. The thickness of the hydrophobic resin layer 14 is determined in consideration of the curvature of the convex lens, the aperture ratio of the photoelectric conversion region, and the refractive index of the dyeing layer and the resin 14 so that all incident light is collected in the photoelectric conversion region.

(Other Embodiments) FIG. 6 is a schematic cross-sectional view of solid-state imaging according to another embodiment, which corresponds to FIG. 5 described in the first embodiment, and portions having the same functions have the same symbols. It is indicated by. The difference from the first embodiment is that the color filter is integrated on the solid-state image pickup device and the convex lens array described in the first embodiment is formed thereon.

In FIG. 6, a substrate semiconductor on which a solid-state imaging device is formed
For example, the same resin layer 18 as the hydrophobic resin layer 14 of the first embodiment is coated on 10, and then a hydrophilic resin layer 19 such as gelatin is formed. After that, for example, dyes of red 20, green 21, and blue 22 are sequentially dyed corresponding to the photoelectric conversion unit 11 by using a photolithography technique. After that, the convex lens array shown in FIG. 6 can be formed by going through the steps of FIG. 2 to FIG. 5 of the first embodiment.

(Effects of the Invention) As described in detail above, according to the present invention, the curvature of the convex lens array can be formed with good control, and the photoelectric conversion efficiency of the interline CCD image pickup device and the MOS type image pickup device can be set to about 100%. .

[Brief description of drawings]

1 to 5 are schematic cross-sectional views of a main part showing an embodiment of the method for manufacturing a solid-state imaging device according to the present invention, and FIG. 6 is a schematic cross-sectional view of another embodiment. 10 is a semiconductor substrate, 11 is a photoelectric conversion unit, 12 is a signal reading unit, 13 is a light shielding unit, 14 is a transparent resin, 15 is a dye mask resin,
Reference numeral 17 is a transparent dye, and 19 is a resin that dyes a color filter.

Claims (1)

[Claims] 1. A solid-state image pickup device comprising: a photoelectric conversion element group formed in a mosaic pattern on a semiconductor substrate; and means for reading out a signal photoelectrically exchanged by the photoelectric conversion element group. The surface is coated with a hydrophobic transparent resin layer, then the hydrophobic transparent resin layer is coated with a hydrophilic resin layer, then the hydrophilic resin layer in the portion corresponding to the photoelectric conversion element group is removed, and then the hydrophilic layer is removed. A method of manufacturing a solid-state image pickup device, comprising: forming a convex lens array corresponding to the photoelectric conversion element group by dyeing a transparent dye by thermal transfer dyeing in an opening of the functional resin layer.