Bottom anti-reflective coating processing techniques for via-first dual damascene processes

As dual damascene process integration continues, Bottom Anti-Reflective Coating (BARC) processing information for partial and full via fill for via-first dual damascene has been an increasing concern. To fill this need a screening design of experiment was used to discover the main factors that would give increased fill and reduce iso-dense bias for both fill and top coverage. This DOE incorporated typical coat and bake module process parameters, such as acceleration, spin speed, and spin time for the dispense, spread and casting steps, and a two stage bake for the bake module. The process steps that were found to affect via fill and iso-dense bias for via fill and top coverage were then used in multi-level process characterizations and are presented here. Multiple viscosities were also tested in these designs to bracket partial via fill processing. Via fill and bias results for via fill and top coverage will be presented for contact vias that have diameters from 300nm to 160nm that range in pitch ratios of dense (1:1) to isolated (1:5).