AMORPHOUS-SILICON CARBIDE AND ITS APPLICATION IN SILICON MICROMACHINING

A new passivation material for application in microsystem technologies is presented for the first time. Silicon carbide is known to have goo d chemical resistance and mechanical properties. The deposition of lay ers reported here was performed in a parallel-plate plasma reactor wit h hexamethyldisilane (HMDS). The HMDS was supplied by a liquid bubbler line and argon was used as carrier gas to provide a sufficiently high flow of gas. The principal deposition parameters investigated are tem perature and r.f. power. These parameters have the most direct influen ce on the layer properties compared to other possible parameters such as total flow, r.f. frequency or total pressure. Besides the primary r esults for deposition rate, homogeneity and step coverage, further imp ortant properties for the application are stress in the layers and etc h resistance. These properties were investigated in relation to the ch emical composition of the amorphous silicon carbide. The amount and ki nd of stress (compressive or tensile) influence the adhesion of the la yers to different materials and also the application as membranes. Tem pering of the carbide at 450 and 1000-degrees-C was also part of our i nvestigation even though the latter temperature is not compatible with aluminium.