Germanium as a versatile material for low-temperature micromachining

Though germanium (Ge) shares many similar physical properties with silicon (Si), it also possesses unique characteristics that are complementary to th ose of Si. The advantages of Ge include its compatibility with Si microfabr ication, its excellent gas and liquid phase etch selectivity to other mater ials commonly used in Si micromachining, and its low deposition temperature (<350 degrees C) that potentially allows Ge to be used after the completio n of a standard CMOS run. Wider applications of Ge as a structural, sacrifi cial, and sensor material require a more systematic investigation of its pr ocessing and properties. The results of such an undertaking are presently r eported, The topics covered are the formation of Ge thin films and novel ap plication of the selective deposition of Ge to etch hole filling, character ization of the effects of thermal treatment on the evolution of the residua l stress in Ge thin films, etch selectivity for etch mask and sacrificial l ayer applications, and gas phase release technique for stiction elimination . [431].