FABRICATION OF MICROCHANNELS BY LASER MACHINING AND ANISOTROPIC ETCHING OF SILICON

Micromechanical structures in silicon are usually fabricated by photolithography and anisotropic etching. While the shape and the size of the pattern on the wafer surface are defined by a masking layer, the dimension of the microstructures perpendicular to the wafer surface depends mainly on the crystallographic orientation of the wafer. Our work presents a method for the fabrication of new types of microstructures with high aspect ratio. This technique is based on the local destruction of limiting {111} crystal planes by laser melting and anisotropic etching of the molten zones. Although the shape and the size of the microchannels are lithographically predetermined, their aspect ratio can be modified by the parameters of the laser beam. The partially closed form of these microchannels is suitable for precise positioning of fibers in hybrid microoptical devices and transport systems for gases and liquids.