Investigation and control of chemical and surface chemical effects during dielectric CMP

Due to the ever-increasing popularity of STI in microelectronic device fabrication, designer slurries must be tailored to meet increasingly stringent planarity requirements. Although dielectric polishing is primarily mechanical in nature, the chemical and surface chemical effects can be tailored to enhance selectivity and planarity. Examples of chemical and surface chemical effects in dielectric CMP include; control of slurry pH, use of reactive particles such as cerium dioxide, and addition of surfactants to modulate the particle-substrate interactions. Cerium dioxide particles are utilized due to an increase in substrate dissolution through particle-substrate bonding, which accelerates the material removal of the dielectric surface. The increased efficiency of reactive particles is largely dependent on the area of contact between particle and substrate during polishing. The chemical nature of the interaction between the particles and silica substrates has been investigated using polishing experiments, AFM, and an in-situ friction force apparatus, Both the pH and cerium dioxide particles have been found to significantly affect the near surface region of the oxide film.