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(C6H10)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 (C6H10), which is very volatile and should readily desorb, thereby leaving the Si core atoms adsorbed on the surface. High purity vapor sources of Si(C6H10)2 were prepared and introduced into a multi-technique ultrahigh vacuum (UHV) chamber. Si(C6H10)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.