It is demonstrated that ther is a difference in the pressure dependence origin of CMP removal rate between a hard and soft pad. It is shown that, in contrast to Preston's equation, the pressure dependence of the removal rate for CMP with soft pads is nonlinear, i.e., RR X P~(2/3). This new model is shown to be consistent with available experimental evidence on CMP of oxide dielectrics. In addition, it is pointed out that the pressure dependence behavior of the CMP removal rate for values of P near zero is needed for a further test of the present and other polishing rate models, for elucidating the direct chemical contribution to the removal rate and thus for a better understanding of CMP mechanisms.
展开▼
