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.