The modification of roughness to corner effect in plasma etching

Abstract

Plasma etching, a quite vital technique for transferring the mask pattern onto the substrate, is subjected to charging phenomena. Compared to the round contact-hole which has been studied by a great deal of previous research on the charging issues, the rectangle mask hole presents a significant corner effect. The case study here thus focuses on several kinds of isolated rectangle mask holes with various edge roughnesses and ratios of length (L) and width (Wd). The modification of the roughness to the corner effect has been investigated using classical particle simulations, including a string algorithm for the evolution of the hole opening. This work shows that the corner effect becomes unobvious with the increase of the dominant amplitude and with the decrease of the wavelength of the roughness. In addition, the simulated results indicate that a small ratio (L: Wd) can reduce the corner effect. Mechanisms behind these observations were explained mainly based on the analysis of the spatial electric field distribution as well as the opening evolution. This study would be beneficial for controlling the rectangle mask pattern transfer.