ArF excimer laser lithography with bottom antireflective coating

Abstract

In ArF excimer laser lithography, the bottom antireflective coating (BARC) technique is essential in inhibiting the effect of interference and reflective notching. We investigated the antireflective effect of commercially available organic BARCs, that had originally been designed for KrF and i-line lithography, and also the patterning characteristics of ArF resists with BARCs. The refractive indices of various materials were measured with a spectroscopic ellipsometer. The real part (n) and the imaginary part (k) of the complex refractive index at 193 nm were 1.4 to 1.7 and 0.1 to 0.8 respectively. Almost all the materials had sufficient antireflectivity at 193 nm. We investigated the patterning characteristics of chemically amplified ArF positive resists with suitable BARC materials. The resolution, the depth-of- focus of patterns below 0.16-micrometer lines and spaces, and the exposure latitude were improved and good critical dimensional control over topography was achieved by using BARC. An acceptable profile after gate structure (BARC, W-Si, and Poly-Si) etching could be obtained under the typical etching conditions used for KrF resists.