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The diffusion parameters of chemical amplification resists are evaluated and analyzed as the functions of illumination condition, resist type and resist thickness. The pattern linearity is also compared among the different types of resist and process conditions. From the experimental results, it is confirmed that the diffusion parameters of dense L/S type resist is sensitively influenced by illumination condition, but those of C/H type resist are less affected by exposure condition due to the limited resolution of resist. Generally, the diffusion parameters seems to be much affected by sigma condition rather than the numerical aperture condition and it does not much influenced by resist thickness within similar thickness range. The 120nm, 100nm and 90nm dense L/S patterns are obtained with high contrast KrF resist of R5767 having diffusion parameter below 0.3 at the conditions of 0.80NA (89/60 sigma) and 2500 Angstrom thickness. Under the validation of DAIM, the most important parameter is the diffusion length of acid. Since the image contrast is given by the cross product of aerial image contrast and the resist function, the lithography performance depends upon not only the aerial image but also the resist function. The resist function is related with pattern pitch and diffusion length. Therefore, the increased value of resist function is required by introducing of high contrast resist having smaller diffusion parameter to induce the smaller pattern formation as explained in this experiment results.