ABSTRACT
Many attempts have been made to apply chemical vapor deposition (CVD) diamonds in other than wear resistant parts and cutting tools. However, diamond is well known as the most suitable material for acoustic parts because diamond has the largest sound velocity. A diamond coated speaker diaphragm was developed as the first product of CVD diamond in 1987. The sound velocity was measured by the vibration method and was 16,500 m/s, which is a little less than the value for single crystalline diamond. A free standing diamond diaphragm fabricated by the CVD method was developed in 1990. Another expected application of diamond is surface acoustic wave (SAW) filters. SAW filters are popular devices in televisions, video recorders, mobile telephones, etc. Introduced electric signal is converted to sound signal and is reconverted to electric signal. Diamond film deposited on a silicon substrate is polished by conventional methods, and an aluminum film was deposited on the diamond film.
