Nanolayer thickness detection via spatial mode projection

TL;DR

This paper introduces an optical method using spatial mode projection to measure nanolayer thicknesses with high precision, achieving sub-10 nm accuracy and enhanced sensitivity, suitable for subnanometric detection.

Contribution

The novel scheme employs spatial mode projection of reflected light to accurately measure nanolayer thicknesses, improving sensitivity and enabling detection below 10 nm.

Findings

Measured step height smaller than 10 nm

Achieved picometer-scale measurement error

Enhanced signal-to-noise ratio for better sensitivity

Abstract

We demonstrate an optical scheme for measuring the thickness of thin nanolayers with the use of light beam s spatial modes. The novelty in our scheme is the projection of the beam reflected by the sample onto a properly-tailored spatial mode. In the experiment described below, we are able to measure a step height smaller than 10 nm, i.e., one-eightieth (1/80)of the wavelength with a standard error in the picometer scale. Since our scheme enhances the signal-to-noise ratio (SNR), which effectively increases the sensitivity of detection, the extension of this technique to the detection of subnanometric layer thicknesses is feasible.