Influence of thermal treatment of low dielectric constant SiOC(-H) films using MTES/O_2 deposited by PECVD

摘要

Low dielectric constant SiOC(-H) films are deposited on p-type Si(100) substrates by plasma enhanced chemical vapor deposition (PECVD) using methyltriethoxysilane (MTES, C_7H_(18)O_3Si) and oxygen gas as precursors. The SiOC(-H) films are deposited at room temperature, 100, 200, 300 and 400 ℃ and then annealed at 100, 200, 300 and 400 ℃ temperatures for 30 min in vacuum. The influence of deposition temperature and annealing on SiOC(-H) films are investigated. Film thickness and refractive index are measured by field emission scanning electron microscopy and ellipsometry, respectively. Chemical bonding characteristics of as-deposited and annealed films are investigated by Fourier transform infrared (FTIR) spectroscopy in the absorbance mode. As more carbon atoms are incorporated into the SiOC(-H) films, both film density and refractive index are decreased due to nano pore structure of the film. In the SiOC(-H) film, CH_3 group as an end group is introduced into -O-Si-O- network, thereby reducing the density to decrease the dielectric constant thereof. The dielectric constant of SiOC(-H) film is evaluated by C-V measurements using metal-insulator-semiconductor (MIS), Al/SiOC(-H)/p-Si structure and it is found to be as low as 2.2 for annealed samples deposited at 400 ℃.