The properties of silicon dioxide films on silicon as diffusion masks for boron

Measurements of the diffusion constant and segregation coefficient have been made for silicon dioxide films on silicon, using six different methods of preparing the oxide films. The results show that the thermally grown oxides give the best masking properties against the diffusion of boron, but that other oxides, notably reactively sputtered oxide and oxide formed by decomposition of tetraethoxysilane, can be almost as good. It is also shown that the exact method of preparation of the latter two oxides is important; for example, an argon-oxygen mixture gives much better oxide than pure oxygen.