Chemical‐Mechanical Polishing of Parylene N and Benzocyclobutene Films

Abstract

In this paper, we have investigated the quality of benzocyclobutene (BCB) and parylene N (PA‐N) films after chemical‐mechanical polishing (CMP) by x‐ray photoelectron spectroscopy (XPS) and atomic force microscopy. The change of surface chemical structure of both BCB and PA‐N films after CMP is mainly dependent on the slurry composition and the quality of as‐deposited film. Some slurries do not alter the surface structure for PA‐N film, but the surface structure changes for all the slurries investigated for BCB. On the other hand, for both PA‐N and BCB we find that the higher the quality of the as‐deposited film or postdeposition treated film, the higher the quality of the polished film. The polishing time has little effect on the surface chemistry of high quality PA‐N films, but does affect the BCB films. The surface morphology for these two polymers becomes worse after CMP. The root‐mean‐square surface roughness for as‐deposited PA‐N is 90 Å, but after CMP is larger than 200 Å. The roughness for as‐spin‐coated and polished BCB film is 5 and 20 Å, respectively. A slurry which is good for BCB polishing is not good for PA‐N polishing, and vice versa. We conclude that the nature of the polymer film, including its chemical structure as well as the quality of the as‐deposited/postdeposition treated film, plays an important role in polymer CMP.