Effect of surface pretreatment of submicron contact hole on selective tungsten chemical vapor deposition

Abstract

The effects of various predeposition treatments of silicon substrates on selective tungsten chemical vapor deposition were investigated using the silane reduction process. The predeposition treatments include HF or buffered HF wet etch and/or NF3 plasma etch. The experimental results show remarkable differences in the initial nucleation of W and the smoothness of the W surface and the W/Si interface among the various treatments, as revealed by scanning electron microscope inspection and atomic force microscope analysis. Plasma etch leads to a rough W/Si interface while wet treatment with HF dip results in a fairly smooth interface. The experimental results show that better I-V characteristics for the W/n-Si Schottky contact can be obtained by the wet etch treatment prior to the W deposition. The reverse bias junction leakage for the wet etch pretreated W/p(+)n junction diode is smaller than that of the plasma pretreated diode. In addition, the substrate surface treatments were found to result in Si consumption of various degrees. (C) 1996 American Vacuum Society.