Measurement technique for ultra-thin oxides

摘要

A method of measuring the thickness of ultra-thin (e.g., <200 Å) oxide formed on a semiconductor device uses a reference sample (i.e., another silicon wafer) which has been pre-processed to include a relatively thick oxide surface layer. The thickness of the reference oxide (t) is measured using any conventional technique (such as an ellipsometer). An ultra-thin oxide is then simultaneously formed on both the reference sample and semiconductor device. The total oxide thickness (T) of the dual-layer structure on the reference sample is then measured (again, using any conventional technique), and the difference between the two measured values (T-t=delta) is defined as the thickness of the ultra-thin oxide layer.