Muthiah Thiyagarajan

Study of the Effect of Amine Additives on LWR and LER

We will give an account of our investigation on structure property relationships of amines with regards to line width roughness (LWR) and line edge roughness (LER) of a 193 nm alicyclic-acrylate resist. Specifically, we have looked at basicity, molar volume and logD as factors which may have an influence of roughness of 80 nm 1:1 L/S features. For relatively hydrophobic amines (Log D > -1), the lower the hydrophilicity at acidic pH the greater the LER and LWR becomes. Specifically, in this range of Log D, more hydrophobic larger amines, with higher basicity, tend to give worse L/S feature roughness. For amines which are more hydrophilic, the relationship becomes more complex with some amines giving a lower LER while others do not. This appears to be predicated on a delicate balance between basicity, hydrophilicy and size.

Comparison of thermal flow and chemical shrink processes for 193 nm contact hole patterning

This paper compares thermal shrink properties of contact holes and chemical shrink performance for 193 nm lithography. Pitch dependence, shrink properties, contact hole circularity, sidewall roughness, and process window are also discussed. Thermal flow process exhibited more pitch dependence than chemical shrink process. Thermal shrink rate increased substantially at higher bake temperatures. Contact holes in defocused area shrunk non-evenly and DOF deteriorated upon heating. In chemical shrink process, shrink rate was hardly influenced by mixing bake temperature, contact holes from center focus to defocus area shrunk evenly preserving effective DOF and MEF became smaller at smaller CD. Chemical shrink has clear advantages over thermal flow process and sub-70 nm contact holes were obtained with iso-dense overlap DOF 0.25 μm by optimizing resist formulations and process conditions. Application of shrink processes will pave the way for the next generation LSI production.