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US 5,294,288 AGranted
Forming sol-gel dichroic color filters
AssigneeEastman Kodak Company
InventorsSharon M. Melpolder, Michael J. Hanarahan, Anne W. West
Life of this patent
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Abstract
A process of forming dichroic color filters on substrates, particularly image sensors, includes using a spin-on-glass process to form low and high refractive index layers. A mixture of titania and silica partially hydrolyzed and condensed sol-gel polymer suspension in the high refractive index layer and in the low refractive index layer has a partially hydrolyzed and condensed silica sol-gel polymer suspension are processed and to cause titania to phase change.
Claims1
In a process for forming an integral dichroic color filter array on an image sensor, comprising the steps of:
- (a) coating a planarization layer on the image sensor;
- (b) sequentially depositing a plurality of spin-on glass layers on the planarization layer, wherein two of such spin-on glass layers have different desired indices of refraction with one including a mixture of titania and silica partially hydrolyzed and condensed sol-gel polymer suspension and the other a partially hydrolyzed and condensed silica sol-gel polymer suspension, and after depositing each layer, heating such layer at a temperature less than 300.degree. C. to remove residual solvent and to achieve a desired refractive index without causing a phase change of titania from amorphous to either crystalline anatase or rutile or a combination thereof;
- and exposing the layer containing titania to energy selected to cause titania to phase change from amorphous to either crystalline anatase or rutile or a combination thereof to change the spectral response characteristics of the filter.
Dependencies are inferred from the claim text.