Acid diffusion analysis in the chemically amplified CARL resist

The demand for smaller device dimensions in microlithography drives the need to understand and control diffusion during photoresist processing, in advanced chemically amplified systems the lithographic performance is strongly influenced by diffusion of acid and base additives. Diffusion parameters and photoacid generation efficiencies were quantitatively evaluated using an established in situ photometric method employing a pH-sensitive organic dye[1,2]. This method does not require expensive inspection tools and allows estimations of the lithographic performance aside the production environment. A kinetic model for the post-exposure bake (PEB) has been proposed and transferred to transport properties. The experimental data for this model have been obtained from UV/VIS spectroscopy measurements. Rough estimations of effective diffusion lengths are based on molecular reaction dynamics. The influence of the process conditions are discussed in greater detail. Results are used to improve the lithographic performance of the dual-wavelength CARL(R) [3] resist system presently evaluated at Infineon Technologies.