Vapour deposited silicon carbide

Microengineering techniques using silicon have been extensively developed in recent years and a wide range of microstructures can now be routinely achieved. At the same time there has been considerable development in electroforming technology and micro-moulding techniques producing families of microstructures in various metals and polymers. This presentation outlines a method of extending these material options to include hard, refractory materials. Silicon carbide was selected as the material for demonstrating the technique which basically consists of the chemical vapour deposition (CVD) of a thick SiC layer onto a microstructured substrate, followed by the selective dissolution of that substrate to release the free-standing SiC microstructure - which is essentially a negative copy of the substrate. Due to its relatively high temperature compatibility, low thermal expansion coefficient and appropriate chemistry (for selective removal) and well characterised micromachining properties, silicon makes an ideal substrate material