Hard-mask Etch Process Using ArF Photoresist and Conventional ICP System

초록

The ArF photoresist, which can be exposed at 193 nm wavelengths, has been applied in semiconductor manufacturing for a sub-micron feature size and beyond. Recent reports show that ArF photoresist is much weaker and thinner than KrF (248nm) photoresists. Thus, rotecting the patterned ArF photoresist during a plasma etch process may be a key issue of a sub-micron scale semiconductor fabrication process. We tried to etch silicon dioxide and silicon nitride using ArF photoresist. Silicon dioxide and silicon nitride are commonly used as hard masks of subsequent etch process due to their etch characteristics in plasma chamber. So, hard-mask opening process using ArF photoresist is a challengeable work. In this work, deformation characteristics and etch characteristics of ArF photoresist in plasma chamber with various gas chemistries are studied in order to establish an optimized etch recipe. We present an alternative etch process which includes protective layer coating, polymer/photoresist trimming and hardmask etching. These complex reactions are simultaneously occurs during the plasma etch process, and can be controlled by gas mixtures and temperature controls. The ArF photoresist which protected by fluorocarbon polymer shows high selectivity and low deformation characteristics during the plasma etch process, compared with the untreated ArF photoresist. As a result, successful hard-mask etch process more than 200 nm depth was carried without pattern deformations and photoresist depletions. Detailed results and SEM images of the etched samples will be presented.