A light sensor having a chemically resistant and robust reflector stack is disclosed. The reflector stack is formed over a substrate, and includes an adhesion layer, a patterned reflector layer over the adhesion layer, and a smoothing layer over the patterned reflector layer. The patterned reflector layer has a substantially flat top surface. A conformal passivation layer covers the reflector stack. An absorbing layer is situated above the reflector stack and separated from the reflector stack. The absorbing layer is supported by vias over the substrate. The absorbing layer is connected to at least one resistor, where a resistance of the at least one resistor varies in response to light absorbed by the absorbing layer. The vias are disposed on via landing pads on the substrate.