Investigation of hardmask/BARC materials for 157nm lithography

157nm lithography is expected to be the lithography choice for the 100nm-technology node, which is scheduled to be in full-production in 2003. However, due to 157nm photons being strongly absorbed by commonly used polymeric organic materials, a completely new class of material (containing F and Si-O) will be needed for 157nm Single Layer Resist (SLR) system. It is expected that the 157nm SLR system development will take greater than 3 years, which the industry will barely have, until the projected 2003 production schedule. In an attempt to fill the gap and to provide working resist system using thin (<100nm) films of existing resist materials along with inorganic thin hardmask/BARC films is an attractive approach. In this paper, we report the optical constants (n & k at 157nm as well as 193nm and 248nm) of various thin film hardmask/BARC candidate materials (SixNyHz, SixOyNz, SixCy CVD and TixNy PVD films) measured by VUV-VASE. The films' atomic compositions, determined by RBS/HFS, were varied by controlling feed gas flow rates in order to vary the optical behavior. However, we limited our study within the low process temperature PE-CVD and PVD films due to our intention of using these films along with LowK (2.7-2.0) dielectric materials. In addition, we will also report the optical constants of two types of LowK materials (PE-CVD OSG film and Spin-On/Cure low-density organosilicate dielectrics by JSR). The data is, then, used to optimize the physical properties (n & k) and utilized to determine suitable hardmask/BARC material for 157nm exposure using Prolith II simulation. The results containing property of these hardmask/BARC candidate films acid our optimization analysis along with the first successful pattern transfer feasibility demonstration into realistic substrate material (poly-Si) using ultra thin resist (currently existing) at 157nm optical lithography are reported.