Applications of germanium to low temperature micro-machining

Though germanium (Ge) shares similar physical properties with silicon (Si), it also possesses unique characteristics that are complementary to those of Si. The advantages of Ge include its compatibility with Si micro-fabrication, its excellent gas and liquid phase etch selectivity to other materials commonly used in Si micro-machining, and particularly its low deposition temperature (<350 degrees C) which allows Ge to be used after the completion of a standard CMOS run. Clearly, wider applications of Ge as structural, sacrificial, and sensor material require a more systematic investigation of its processing and properties. In this report, the results of a systematic investigation of the use of Ge in MEMS are presented.