In situ infrared study of chemical nature of Si surface in etching solution and water

摘要

The chemical nature of Si(100) and (111) surfaces during immersion in dilute hydrofluoric acid (HF) solution and water was investigated "in-situ" and in real time using infrared absorption spectroscopy in the multiple internal reflection geometry. We demonstrate that in dilute HF solution, Si surfaces are not perfectly terminated by hydrogen, but are covered in part with hydrogen-associated Si fluorides, such as SiH_2(SiF). We find that the hydrogen coverage of the surface duringstorage in dilute HF solution depends on the HF concentration of the solution. It is shown that rinsing in water sollowing HF treatment leads to complete hydrogen termination of the surface. We also show that hydrogen exchangereaction occurs on the hudrogen-terminated Si surface during storage in water.