CHEMICAL-MECHANICAL POLISHING IN SEMIDIRECT CONTACT MODE

In a typical chemical-mechanical polishing (CMP) process for interlevel dielectric planarization, the oxide removal rate is strongly dependent on the parameters such as applied load, relative speed, and pad surface properties. However, the experimental results presented in this work show that by maintaining a thin fluid film between the pad and the wafer and thereby reducing the role of the asperities in the pad, the oxide removal rate can be made independent of these polishing parameters. In this semidirect contact mode, the CMP process, carried out on 2 in. wafers, resulted in a uniform polish rate across the wafer, high run-to-run reproducibility, high selectivity between materials of differing chemical properties, and eliminated the need for pad surface conditioning and in situ end-point determination equipment.