Issues Of Wet Cleaning In ULSI Process

Wet cleaning for actual LSI processes is discussed. Particle elimination efficiency is limited by suppression of device degradation and cleaning is invalid for the particles generated during etching and film formation. Particle reduction depends on particle characteristics, i.e. the sticking force and the chemical structure of the particles. Metallic contamination on wafers, dependent on a kind of solutions and the concentration in a solution, degrades TDDB characteristics and recombination lifetime. Although the lifetime degradation is a serious problem for ULSI, the damage by etching and by ion implantation causes the lifetime lowering rather than metallic contamination.