Three-dimensional impurity profiling using chemical etching and scanning tunneling microscopy

Abstract

Scanning tunneling microscopy on cleaved silicon surfaces, chemically etched with HF-HNO 3-H 2O solution, exhibits boron impurity concentration profiles with 10 nm resolution. This method is applicable to a wide impurity concentration range of 10 16−10 20 cm -3 and outperforms the impurity profiling method using current-imaging tunneling spectroscopy in its ability to measure lower impurity concentrations of less than 10 17 cm -3. Impurity profiling is demonstrated with a metal-oxide-silicon structure, and it is found that the lateral junction depth in the test structure is 70% of the junction depth and the impurity profile in the sidewall region shows an almost straight-line impurity distribution.