A new CVD reaction for atomic layer deposition of silicon

We have investigated a new reaction pathway for atomic layer deposition of Si on various metal and semiconductor substrates using a novel organosilicon compound, Si(C ₆ H ₁₀ ) ₂ , which has a central Si atom with two identical 5-fold hydrocarbon rings. Upon reaction with the substrate the hydrocarbon rings are expected to transform into dimethylbutadiene (C ₆ H ₁₀ ), which is very volatile and should readily desorb, thereby leaving the Si core atoms adsorbed on the surface. High purity vapor sources of Si(C ₆ H ₁₀ ) ₂ were prepared and introduced into a multi-technique ultrahigh vacuum (UHV) chamber. Si(C ₆ H ₁₀ ) ₂ molecule was initially physisorbed at liquid nitrogen temperature (∼ 100 K) at a pressure of 1.0 × 10 ^-6 Torr to either monolayer or multi-layer thickness on substrates. Infrared reflection-absorption spectroscopy (IRAS) and core-level X-ray photoelectron spectroscopy (XPS) of the Si(2p) have shown evidence of an adsorbed 'silylene' species formed at 200 K due to the loss of one 5-fold hydrocarbon ring. Thermal desorption data support the dissociation of the molecule and the liberation of the hydrocarbon reaction product, dimethylbutadiene. However, upon further heating the 'silylene' species decomposes non-selectively to produce both silicon deposition and carbon contamination.