Low Energy X-ray Emission Spectrometry, LEXES Analysis

Low Energy X-ray Emission Spectrometry (LEXES), is a near surface analytical technique that utilizes a low energy electron beam as an excitation source. Atoms that are excited by the electron beam relax under the emission of characteristic x-rays. Similarly to EDS, LEXES analysis measures the energy of the emitted x-rays, which are characteristic of elements present in the near-surface region of a sample. The use of Wavelength Dispersive Spectrometers (WDS) increases the sensitivity of the technique and improves energy resolution, removing most interferences.

The electron beam current can be very tightly controlled, allowing for very high precision measurements. Dopant concentrations, film composition, and/or film thickness can be mapped across wafers or compared between wafers with precisions of 1% or better. By using reference standards measurement accuracies of better than 5% can be obtained. Adjusting the energy of the incident electron beam allows layers as thin as 10Å or as thick as 1µm to be analyzed. Finally, the LEXES electron beam can be focused into an area as small as 10µm, allowing small areas to be analyzed.

Main Applications

• High precision measurement and full wafer mapping of dopant dose, thin film composition, thickness, and impurities