INTEGRATED GRATING DETECTOR ARRAY FABRICATED IN SILICON USING MICROMACHINING TECHNIQUES

Silicon bulk micromachining techniques have been employed to fabricate an integrated grating and detector array in silicon for operation in the visible and near-infrared spectral range. Two wafers are machined in such a way that an optical path of about 4 mm in length is obtained in which dispersed light from a 32-slit diffraction grating is projected onto an array of photodiodes. The wafers are subjected to an electrochemically controlled etch. The interior of one of the wafers is subsequently coated with a reflective film. The grating and the array of photodetectors are integrated in the second wafer, which remains uncoated. The wafers can be bonded using the direct silicon-to-silicon fusion bonding technique. The functional division into a reflective wafer and a grating/readout wafer greatly simplifies the integration of the complete device in a smart silicon sensor.