Diffraction grating scanners using polysilicon micromotors

摘要

This paper describes polysilicon micromotors with single andnpyramidal diffraction grating elements fabricated on the polishednsurface of large-area rotors for optical scanning applications. Whilentaking full advantage of planar processing, such scanners havenhigh-quality scan profiles, good efficiency, meter working distances,nand multiple out of plane beam diffraction orders. Chemical-mechanicalnpolishing was used to reduce the 5-Μm-thick polysilicon rotors'naverage surface roughness from 420 Å to below 17 Å, withnless than 1500-Å film removal, improving the optical performancenof the gratings as well as the definition, delineation, and side wallnquality of the device features. Self-assembled monolayers (SAM) werenfound to improve the overall micromotor's dynamic performance.nSAM-coated scanners could operate at voltages as low as 15 V and maximumnoperational speeds of 5200 rpm. The gratings were tested optically atn633-nm wavelength and were verified to have spatial periods of 1.80 andn3.86 Μm, closely matching their design values. Stepping andncontinuous mode dynamic operation of the scanners was demonstrated withnvisible diffraction orders at meter distances away