Paper PS1-WeM10
Dependence of Carbon Removal Rate on the Structure of Porous Low-k SiOCH Films during N₂/H₂ Plasma Processes

Wednesday, October 22, 2008, 11:00 am, Room 304

To realize highly reliable interconnects for sub 32 nm node LSI, low-k materials such as porous SiOCH films are demanded to be resistant to plasma processes, such as etching and ashing. This is because a methyl group which makes hydrophobic film is easily abstracted from the film during the plasma irradiation processes. We have examined the plasma resistance of SiOCH films which contained the methylene-bridge (Si-CH₂-Si) structure¹ using a plasma beam irradiation apparatus.² This apparatus enabled us to carry out plasma-surface interaction experimens using identified irradiation species. We used two kinds of spin-on-glass porous SiOCH films (k=2.0). One contained only methyl groups, and the other contained both methyl groups and methylene bridges. Used gas chemistry was nitrogen and hydrogen gas mixture plasma. We assumed the damage of the pattern sidewall and irradiated only neutral species from the plasma to the SiOCH films. Major irradiated neutral species were NHx (x=1-4) in addition to parent gases. We evaluated the damage of the film by using the decrease ratio of the carbon content measured as an index by XPS and FTIR. It was found that the decrease ratio of carbon in the SiOCH film contained only methyl groups was larger than that in the film contained methylene bridges. The authors thank JSR Corporation for supplying the SiOCH films.

¹ H. Miyajima et al. Proc. of Advanced Metallization Conf. 37 (2007).
² K.Kurihara et al. J. Vac. Sci.Technol. A 22, 2311(2004).