New nano-patterns generated by the self-assembling of PS spheres during ICP etching

Polystyrene sphere is widely used as mask for wet-chemical or dry-plasma etching. During our inductively coupled plasma etching of silicon (100) surface to fabricate honeycomb structure, some self-assemble phenomena of the polystyrene sphere have appeared and new glam patterns have been observed under appropriate process. For the close-packed polystyrene spheres, a polystyrene membrane with highly ordered periodic regular triangle pores is obtained. And for the scattering polystyrene spheres, every polystyrene sphere have transformed to 3-5 “side-by-side goldfishes”. The affects of the flow of C₄F₈ on the patterns achieved have been investigated, and it is concluded that gas flow is a very important factor that affect the patterns generated by the self-assembling of the polystyrene spheres during etching process. The etching recipe reported here provides a technology to fabricate large area highly ordered polystyrene membranes with regular triangle or square pores. These membranes can be used as masks to fabricate triangular or square arrays of nano-pillars or nano-pores by wet-chemical or dry-plasma etching technologies.