Deposition of hafnium silicate films by liquid injection MOCVD using a single source or dual source approach

Two approaches have been investigated for the MOCVD of high-k hafnium silicate (HfSixOy) films for gate dielectric applications. The first approach using the novel "single source'' precursor [Hf((OSiBuMe2)-Me-t)(4)(Et2NH)], gave a level of Si (similar to10 at%) which showed little variation over a range of growth temperatures and oxygen partial pressures. The second, more flexible approach, uses two separate Hf and Si sources, Hf(NMe2)(4) and (BuMe2SiOH)-Me-t, and allows good control of the Si concentration in HfSixOy, depending on the relative precursor ratios, up to a maximum level of 18 at%. The dielectric properties of the HfSixOy films deposited by this method were shown to be very good. In the dual source process it is proposed that an intermediate containing direct Hf-(OSiBuMe2)-Me-t bonds is formed in situ in the gas phase. The crystal structure of [Hf((OSiBuMe2)-Me-t)(4)(Et2NH)] is also reported.