Thermal cure study of a low-k methyl silsesquioxane for intermetal dielectric application by FT-IR spectroscopy

In this paper, Fourier transform infrared (FT-IR) spectroscopy is used to study the thermal properties of methyl silsesquioxane (MSQ), an important low-dielectric-constant organic spin-on glass for semiconductor device fabrication. The compositional and structural changes of MSQ with temperature are investigated in detail. The cross-linking process, where the three-dimensional networked structure is formed, is found to start at room temperature, and is almost complete at the typical baking temperature of 250 degrees C, Further cross-linking occurs during the curing process at 425 degrees C, and small short-chain clusters call also be driven away at this temperature by sublimation. In this study, we have assigned all the MSQ IR peaks and se have used the long-chain O-Si-O IR peak to calculate the "degree of cross-linking" quantitatively.