Multifunctional collimator for contact image sensors

A semiconductor device, comprising:

• at least one optical sensing element;
• and
• an optical collimator;
• wherein the optical collimator comprises:
• a first dielectric layer, a first substrate, and a plurality of via holes, wherein the first dielectric layer is formed over the first substrate, wherein the plurality of via holes are configured as an array along a lateral direction of a first surface of the first dielectric layer, wherein each of the plurality of via holes extends through the first dielectric layer and the first substrate from the first surface of the first dielectric layer to a second surface of the first substrate in a vertical direction, wherein the first substrate has a bulk impurity doping concentration equal to or greater than 1×1019 per cubic centimeter (cm−3) and a first thickness, and wherein the bulk impurity doping concentration and the first thickness of the first substrate are configured so as to allow the optical collimator to filter light in a range of wavelengths.