Selective Chemical Vapor Deposition

Selective area deposition has received much attention in IC technology in the past forty years. Its advantage in IC technology is that one saves a mask and a full sequence of lithography, etching, resist removal and cleaning. In Selective Chemical Vapor Deposition (CVD) the selectivity is obtained by the different chemical behavior of reactants with different surfaces. The advantage of selective CVD is the self-alignment with respect to the previous pattern, which allows for tight design-rules in this phase of the IC production. Selective epitaxial Silicon deposition was investigated in the sixties of the last century. Later selective Tungsten, selective epitaxial SiGe, selective IH-V and II-VI compounds and recently selective deposition of Copper became intensively researched subjects. In these cases of selective deposition one etches a window in a dielectric to the substrate and then deposits the required layer. Due to nucleation matters it starts to grow immediately on the substrate material whereas the nucleation on the dielectric is retarded. However, in nature one never gets advantages for free. Selectivity loss, reaction with the substrate material, facetting, lateral overgrowth on the dielectric and pattern-density dependency are major problems.