Boron-doped polysilicon: Growth kinetics and structural study of low-pressure chemical vapour deposited films in the case of high doping levels

In this paper, we present new experimental and theoretical results concerning the deposition of in situ boron doped silicon from BCl3 and SiH4 in a conventional low pressure chemical vapor deposition (LPCVD) reactor. Attempts have been made to increase the doping level compared to what have been done in previous works, in order to reach the alloy lin-dt and look at the resulting kinetics and properties of crystallisation and conduction. In parallel, simulations have been performed, with the aim of understanding and describing properly the chemical and physical phenomena leading to the rate of deposition of boron and silicon. The building of such a model in the case of highly doped silicon emphasises the role of the position (substitutional or interstitial) of boron in the silicon matrix. Indeed, a strong correlation appears between the amorphous or crystalline nature of the film and its deposition kinetics. In turn, the crystallisation of the deposited silicon is a non monotonous function of the boron content, leading to a complex dependence of the kinetics on the operating parameters, together with non-linear time dependent rates of growth.