Application specific spectral response with CMOS compatible photodiodes

Several methods are presented for realizing photodiodes with independent sp ectral responses in a standard CMOS integrated circuit process. Only the ma sks, materials, and fabrication steps inherent to this standard process mer e used. The spectral responses of the photodiodes were controlled by 1) usi ng the SiO2 and polycrystalline Si as thin-film optical filters, 2) using p hotodiodes with different junction depths, and 3) controlling the density o f the interfacial trapping centers by choosing which oxide forms the Si/SiO 2 interface. Also presented is an example method for constructing photo-spe ctrometers using these spectrally-independent photodiodes. This methods for ms weighted sums of the photodiodes' outputs to extract spectrographic info rmation.