Moth-eye anti-reflection structures in silicon for Long Wave IR applications

Novel moth-eye anti-reflection structures in Si for the 12-16 mu m wavelength range have been manufactured and compared to simulations. These structures show a 5-percentage point increase in transmission compared to untreated wafers. Simulations show strong indications that these structures may be further refined for a 10-percentage point increase in transmission and application in the 8-12 mu m LWIR wavelength region associated with thermal cameras. The structures are realized using a single oxide mask and an anisotropic-isotropic-anisotropic etching process. These structures are highly temperature resistant compared to traditional anti-reflection coatings, and therefore lend themselves well to, amongst other things, moderate temperature processes like SLID bonding, which is an attractive approach for hermetic sealing of microbolometer array-based thermal cameras.