Because of their superior characteristics for material processing, energetic cluster beams have been utilized for shallow junction formation, thin film formation, surface smoothing and etching. Recently, we have demonstrated extremely high-speed etching of silicon using hyper-thermal ClF₃ cluster beam. Etching rates of several tens of mm per minute, much higher than conventional reactive ion etching (RIE), were obtained. Molecular dynamics (MD) simulation reveals that high temperature and pressure at the impact zone, resulting from multiple collisions of incident energetic ClF₃ cluster, enhance the dissociation of ClF₃ and the reaction to form volatile products, such as SiF_x. Furthermore, a cluster beam is highly directional, because it is generated with adiabatic expansion. Consequently, a deep trench of 1 mm width was fabricated with photoresist mask. In addition, the etching selectivity of photoresist to silicon is infinite, because of the extremely low incident energy. This simple energetic cluster beam process could be suitable for deep and high-speed etching used for 3D integration of LSIs and microelectronic mechanical system (MEMS) devices.

Recent progress in this novel technique will be presented and discussed in view of its application in micro and nano fabrication.