Endpoint detection development for 70 nm technology Cr etch process

Abstract

For the last few years several different photoresists and Cr layers were used for mask making: -I line resist for 363.8 nm laser writer; -e-beam resist; -Positive CAR resist and DUV CAR resist. Introduction of a new resist into production has several risks associated with and requires process adjustments in litho and etch process likewise. This presentation will focus on the differences in the endpoint detection using optical emission spectroscopy (OES), especially at low Cr load, when using above mentioned photo resists. Development of the OES endpoint detection starting from single wavelength is shortly discussed and methods for endpoint detection at low Cr concentration in the gas phase caused by decreasing plasma power and increasing volume of the etch chamber are shown. An important factor for the practical use of the endpoint detection is the reliability, scalability for different Cr loads and dependence on the chamber seasoning. These factors will be discussed finally.