Hitachi Chemical Co., Ltd. has obtained a basic patent of its CMP slurry which is based on self-activated cerium oxide particles. When manufacturing semiconductor devices, the slurry allows the unnecessary silicon oxide layer on the wafer to be polished away at high rate with the minimum of scratches in the Chemical Mechanical Planarization (CMP) process.
CMP is a process for polishing and smoothing uneven surfaces of wafers (silicon oxide layer, interlayer insulation film, wiring metal layer, etc.) generated in the device isolation or wiring process for semiconductors. CMP slurry is a type of polishing solution used for this application. Particularly in applications for polishing away silicon oxide layers, CMP slurries based on silica particles or cerium oxide particles have not been very successful in satisfying high removal rates and few scratches. As polishing scratches caused by CMP slurries lead to increased defectives, it has been critical to develop CMP slurries that allow faster removal rates with fewer scratches for improved productivity and reliability in manufacturing semiconductor devices for high-speed and highly-integrated circuits.
By applying its ceramics manufacturing technology based on many years of experience, Hitachi Chemical has succeeded in developing CMP slurry composed of self-activated cerium oxide polishing particles, which allows high removal rate with the minimum of scratches. Cerium oxide particles in the CMP slurry have crystalline grain boundaries. They disintegrate under polishing pressures and provide newly activated surfaces which are ready to react chemically with the silicon oxide layer. CMP slurry based on this type of cerium oxide particles makes it possible to keep polishing scratches to a minimum while increasing the removal rate.
Hitachi filed foreign counterpart in the U.S. and in the countries of Europe and Asia to provide worldwide patent protection and to differentiate their unique technology of the recently-developed CMP slurry based on self-activated cerium oxide particles.