CHEMICAL-MECHANICAL POLISHING OF LOW-DIELECTRIC-CONSTANT SPIN-ON-GLASSES - FILM CHEMISTRIES, SLURRY FORMULATION AND POLISH SELECTIVITY

Alkyl siloxane-based low-dielectric-constant (low-k) spin-on-glass (SO G) thin films with varying amounts of organic content were subjected t o polishing experiments using silica-and ZrO2-based slurries with a va riety of additives, As the amount of organic content in SOG increases, the chemical-mechanical polishing (CMP) removal rate decreases with s ilica-based potassium hydroxide-added slurry. On the other hand, zirco nia-based slurry resulted in higher removal rates for both SOG (>400 n m/min) and thermal oxide and an adjustment in polish selectivity (rela ted to thermal oxide) ranging from 1.2 to 9.1 can be achieved by addin g various amounts of tetra-alkyl substituted ammonium hydroxide. Post- CMP materials characterization by Fourier transform infrared spectrosc opy (FTIR) and atomic force microscopy (AFM) shows the chemical stabil ity and CMP compatibility of SOG thin films. (C) 1997 Elsevier Science S.A.