CMOS compatible optical filter for high-throughput enzymatic analysis devices

This paper relates to the use of a thin film of re-crystallized (polycrystalline) silicon as a narrow-band rejection filter in the ultraviolet light range and more particularly to the use of this layer as a protective mask for semiconductor photodiodes. The polycrystalline silicon filters were fabricated by laser annealing a thin film of amorphous silicon deposited by an LPCVD process. In order to produce such films on top of CMOS implemented diodes, annealing was done by excimer-laser irradiation. Using SEM, we compared the crystallization process of the LPCVD silicon film deposited on glass film and on a BPSG layer (boron phosphor silicate glass), available as standard in CMOS.