Analysis of Scratches Formed on Oxide Surface during Chemical Mechanical Planarization

Abstract

Scratch formation on patterned oxide wafers during the chemical mechanical planarization process was investigated. Silica and ceria slurries were used for polishing the experiments to observe the effect of abrasives on the scratch formation. Interlevel dielectric patterned wafers were used to study the scratch dimensions, and shallow trench isolation patterned wafers were used to study the effect of polishing parameters, such as pressure and rotational speed (head/platen). Similar shapes of scratches (chatter type) were observed with both types of slurries. The length of the scratch formed might be related to the period of contact between the wafer and the pad. Large particles would play a significant role in increasing the number of scratches. The probability of scratch generation is more at higher pressures due to higher friction force and removal rate. The optimization of the head to platen velocity could decrease the number of scratches.