Low-k SiOCH film deposited by plasma-enhanced chemical vapor deposition using hexamethyldisiloxane and water vapor

We have developed low dielectric constant SiOCH films by plasma-enhanced chemical vapor deposition (PE-CVD) using hexamethyldisiloxane (HMDSO) containing a siloxane structure and water vapor (H2O) gases. Although the film was deposited using H2O vapor, the content of H2O is very small and the k value can be reduced to the order of 2.5. The leakage current is small and on the order of 10(-9) to 10(-10) A/CM2 at 1 MV/CM2. The hardness and Young's modulus are larger than 2 and 10 GPa, respectively at the k value of 2.8. However the values decrease abruptly with decreasing k value. The mechanism in which the structure and Young's modulus of PE-CVD low-k film decrease with changing k value and deposition conditions is discussed.