Effects of residual water in spin-on-glass layer on void formation for multilevel interconnections

Abstract

Enhanced void formation observed for first-level Al-Si lines under a large area of second-level Al-Si lines is discussed. The void formation depended on both the annealing temperature of the second-level metal and cure conditions of spin-on-glass films used for the planarization. Studies of thermal desorption with Fourier transform infrared spectroscopy revealed that the residual Si-OH components in spin-on-glass films provided a significant amount of water outgassing, and that water desorbed through interdielectric films but not through Al-Si films. Pressure-cooking states were produced under the second level Al-Si metal during the metallization anneal. A gaseous pressure mechanism to explain the enhanced void formation is proposed.<>