Retardation in the chemical-mechanical polish of the boron-doped polysilicon and silicon

This letter reports on the chemical-mechanical polishing (CMP) of boron-doped polysilicon and silicon. Successive polishing was carried out to investigate how the removal rate correlates to the boron concentration as a function of depth in the polysilicon and crystalline silicon. It is found that the removal of boron-doped samples is significantly retarded and strongly correlated with the doping concentration. To the author's knowledge, this work is the first report discussing the retardation effect of boron in the Si-CMP process. This effect is attributed to the activated dopant atoms which are conjectured to inhibit the hydrolysis reaction of Si-Si bonding in the alkaline aqueous solution. In our study, the retardation effect is evident for boron concentration higher than 5/spl times/10/sup 18/ cm/sup -3/. As a consequence, it may become an issue in the CMP process for those layers of selected or complemented doping.