Technological Approaches in Nanopolishing for Microstructures

Polishing technology has been broadly used in manufacturing of components to enhance the surface quality at final processing stage. On the threshold for the 21th century, all of technologies are changing more rapidly than the past. One of them is the miniaturization of the smart systems that require new technological approaches in manufacturing processes. Scientists and engineers have some responsibilities to revise the terminology and expand the area of each technology from the conventional one to nanoengineering. This paper focuses on the introduction of new technological approaches in nanopolishing for microstructures that imply new additional concepts on the conventional polishing. New concepts include damage-free, planarization, nanotopography and conformalization. Damage-free means to get not only atomic level surface roughness, but also subsurface without any physical defects. As one of the emerging methods, chemical mechanical polishing (CMP) is introduced with chemical reaction on the conventional mechanical polishing. Planarization is one of the fabrication processes for semiconductor devices, to make flat from the bumpy or rugged pattern surfaces for rearrangement of ULSI below quarter microns. Representative applications are reported with IMD, STI, copper and low-k CMP. Nanotopography means nanofeatures having 0.2~20mm wave length covered between nanoroughness (10-100nm) and flatness. It influences on the deterioration of threshold voltage, dielectric breakdown and failure of CMP of thin blanket film. Final issue is pointed to the conformalization which means isotropic removal of microstructures to improve the roughness while maintaining the micro three dimensional forms. Electrorheological and magnetorheologi- cal fluid (ERF or MRF) assisted polishing techniques are summarized with their material removal mechanisms and some results