Utilizing Roughness Power Spectral Density Variables to Guide Resist Formulation and Understand Impact of Frequency Analysis through Process

Linewidth roughness (LWR) remains a difficult challenge for improvement in all resist materials. In this paper, we intend to focus on the impact of key components of LWR by analyzing the power spectral density (PSD) curves which can be obtained using Fractilia's MetroLER computational software. We will study systematic changes to ArF resist formulations and correlate these changes with the overall PSD curves. In this manner we will use frequency analysis information to guide resist formulation improvements. We will also investigate the relationship between frequency roughness components and LWR through lithographic / etch processing and demonstrate which components correspond with the largest impact. In order to achieve quality data over low and high frequency ranges we changed our standard metrology setup to capture longer lines. By making systematic changes to the ArF resists, we can determine the key impacts of various controllable resist factors on the PSD. Through systematic analysis, we can deconvolute LWR improvements both after develop and after an etch process.