Characterization of tetra methyl cyclo tetra siloxanes-based low-k dielectric film

In this work, chemical vapor deposited low-k films using tetra methyl tetra cyclo siloxanes (TMCTS) precursors were studied. Process parameters studied included low-frequency RF (LFRF) power, high-frequency RF (HFRF) power, pressure, CO₂ flow rates, and precursors flow rate. Results indicated that the reduction of LFRF power, CO₂ flow rate, and increase in HFRF power, pressure, TMCTS flow rate reduces the dielectric constant (k). In the TMCTS flow rate, there are two reaction's mechanisms which are mass transport-limited and reaction-limited that govern the reaction at low flow rate and high flow rate of TMCTS, respectively. Oxygen in the process plasma played a major role in breaking the Si-CH₃ and Si-H bonds and forming a silica-like structure having higher k. It was found that the k as inversely proportional to the Si-CH₃/Si-O ratio and having a linear relationship with hardness and modulus. The low-k films demonstrate good stability and good adhesion property.