Interplay of physical and chemical aspects in the PECVD and etching of thin solid films

The deposition and etching of thin solid films by means of weakly ionized plasmas is discussed here with the aim of stressing the interlink between the involved physical events and their related chemical reactions. This is particularly important in two situations. First in the gas phase, where the concentration, energy, and reactivity of ions, electrons, radicals, and excited molecules generated by electronic reactions influence the electromagnetic field employed to sustain the plasma, the electron energy distribution function, the time evolution and spatial distribution of the electronic temperature and density. Then secondly on the film surface the ionic surface bombardment has a significant impact on the surface chemistry, which eventually determines the film morphology. In this work we report on the progress of theoretical approaches that correctly describe complex systems where chemical and physical aspects are strongly coupled. We show how it is now possible to formulate detailed plasma reactor models that can predict the concentration of the different charged and neutral species in the gas phase, their gas phase and surface reactivity, growth and etch rates, and the film morphological and compositional evolution. The modern approach takes advantage of the progress in computational chemistry and molecular dynamics to calculate the unknown parameters needed as input to the reactor model. Some examples where the mentioned approach is applied are given.