Hillock formation, hole growth and agglomeration in thin silver films

Thin silver films deposited onto quartz substrates by cathodic sputtering showed hillock growth on annealing in vacuum and in atmospheres of oxygen, helium and argon. Further heating in an oxygen atmosphere caused hole growth and finally led to agglomeration in the films, whereas no hole formation or agglomeration was observed on annealing the films in vacuum and in helium or argon atmospheres. The phenomenon of hillock formation observed in the present case has been explained on the basis of thermal stress relaxation occuring by diffusion creep, with the additional effect of the high surface diffusion of silver atoms on an oxygen-covered silver surface. The hole growth observed as a result of annealing in an oxygen atmosphere could be suitably explained by surface diffusion of silver atoms while the agglomeration occurs during the process of achieving a minimum energy configuration.