<title>New submicron dimension reference for electron-beam metrology system</title>

Abstract

A novel submicron dimension reference for calibrating electron-beam metrology systems has been developed. A fine rectangular-profile diffraction grating fabricated by laser interferometer lithography and anisotropic chemical etching of (110) crystalline silicon satisfies any conditions for submicron dimension reference. In this reference, pitch size of about 0.2 micrometers is easily obtained by laser interferometer lithography with an accuracy, shown by optical diffraction measurement, of within 1 nm. This reference also satisfies several requirements for electron-beam metrology systems. It is stable and free from build-up of charge under electron-beam irradiation because it is fabricated from a conductive silicon single crystal. Also it generates high-contrast secondary electron signals due to high-aspect ratio grating profile. Evaluation of this reference by optical diffraction measurement and electron- beam CD measurements show high performance for submicron dimension calibration. In electron-beam CD measurements, the deviation of repeated measurements is under 5 nm within 3 (sigma) .