Effects of Molecular-Weight Distributions of Resist Polymers and Process Control on Lithography for 0.1μm and Below

抄録

We describe how molecular-weight distributions of resist polymers and process control affect lithography for 0.1μm and below, especially for negative-type resists. There are two main issues for precise critical dimension (CD) control and high resolution in the region: microscopic pattern fluctuation caused by ultrasmall edge roughness in fabricated resist patterns (nano edge roughness); and pattern-size change due to acid diffusion in chemical amplification resists. We have found that nano edge roughness and acid diffusion can be suppressed by controlling the molecular-weight distributions of the base matrix polymers. It is also quite important to control process conditions to achieve high pattern fidelity with molecular-controlled resist materials. Multi-step post baking was applied to minimize the resist pattern deformation before dry etching. We have found that this process can suppress pattern size variations to within 10nm.