Patent ID: 6043001
Filing Date: 2000-03-28
Classification: G02B,G03F

Abstract:
A method for forming lenslets which collect light and focuses the light onto photosensitive elements of a solid-state imager, comprising the steps of:(a) providing a first etch-stop layer on a spacer layer formed on a substrate or layer(s) on a substrate;(b) providing a first photosensitive resin layer on the first etch-stop layer and patterning the first photosensitive resin layer to form a first mask pattern wherein the first mask pattern defines an array of open regions corresponding to the lenslet array to be formed such that the area of each open region is less than and covered by the area of the footprint of the corresponding lenslet and wherein the first mask pattern also defines the areas of the spacer layer which are to be removed;(c) performing an etch transfer of the first mask pattern of the first photosensitive resin layer to the first etch-stop layer to form a first etch-stop mask pattern in the first etch-stop layer, and removing the first photosensitive resin layer;(d) providing a transparent lenslet-forming layer over the spacer layer;(e) forming a second etch-stop layer on the transparent lenslet-forming layer and patterning a second photosensitive resin layer on the second etch-stop layer to form a second photosensitive resin mask pattern wherein the second photosensitive resin mask pattern corresponds to the lenslet array to be formed and wherein the lenslet array defined by the second mask photosensitive resin pattern is aligned to the array of open regions of the first etch-stop layer;(f) transferring by etching the pattern of the second photosensitive resin layer to the second etch-stop layer to form a second etch-stop mask pattern;(g) anisotropically plasma etching the transparent lenslet-forming layer according to the second etch-stop mask pattern to form a transparent lenslet precursor;(h) anisotropically plasma etching the spacer layer according to the first etch-stop mask pattern;(i) isotropically etching to remove remaining portions of the first etch-stop layer forming the first etch-stop mask and portions of the second etch-stop layer forming the second etch-stop mask so that the remaining transparent lenslet precursor is undercut; and(j) thermally reflowing the patterned transparent lenslet precursor to form the lenslets directly on the spacer layer.