Deposition of SiOC by plasma-free ultra-low-temperature ALD (ULT-ALD) and its passivation on p-type silicon

SiOC thin films have been successfully deposited using carbosilane compounds with ultra-low-temperature ALD (ULT-ALD) around 50°C to 70°C. This plasma-free ULT-ALD eliminates the damage to the silicon surfaces due to plasma and high temperature. Silicon substrates with native oxide, as well as hydroxyl terminated silicon, without a pre-cleaning, can be passivated by this method , which greatly shortens the processing time in fabrication. Lifetime tests show that the SiOC film deposited by precursors R#2 (Air Liquide proprietary) and a BTCSM precursor can passivate the p-Si substrates giving a lifetime of up to 349μs. XPS and FTIR analysis shows that the film is approximately 10%C, 40%O and 50%Si with trace amounts of N and Cl. Most of the films' lifetime performances follow an exponential decay with time when exposed to air. Some of the relatively thinner samples do have good stability in that they can maintain 80% passivation performance for two days. Moreover, an increase in lifetime is observed when samples are heated to 100°C, which might be related to hydrogen migration in the film.