PREVENTION OF MICROROUGHNESS GENERATION ON THE SILICON-WAFER SURFACE IN BUFFERED HYDROGEN-FLUORIDE BY A SURFACTANT ADDITION

In order to prevent microroughness generation on the Si wafer surface in buffered hydrogen fluoride (BHF), the addition of a surfactant to B HF was investigated. It was found that microroughness generation on th e Si wafer surface in BHF was prevented by adding the several 10 ppm s urfactant. Also, the dissolution of Si into BHF from the Si wafer surf ace was suppressed by adding the surfactant. Microroughness generation was suppressed by lowering the NH4F concentration in BHF and the diss olution of Si depended on the OH- concentration rather than on the HF concentration in BHF. For a wide range of HF and NH4F concentrations i n BHF, the hydrocarbon anionic surfactant is effective for the prevent ion of microroughness generation. The prevention of microroughness gen eration is explained by the adsorption of the surfactant molecules on the Si wafer surface in accordance with the Langmuir type adsorption e quation.