Advances to smaller memory chip nodes has brought about challenges of accurately fabricating and monitoring increasingly narrow and high aspect ratio (HAR) features. Among these, the HAR etching process is considered the most critical and intricate step in the entire manufacturing flow. The production of high-quality HAR features require methodologies to tackle a range of process errors, including incomplete etching, bowing, twisting, tilting and CD variation. We present both theoretical insights and experimental evidence to highlight CD small-angle x-ray scattering (CDSAXS) as a powerful method for monitoring process variations such as tilt and bending signatures. This nondestructive approach holds immense potential as a rapid screening tool to detect etch process excursions. This method is model-free and eliminates the need for lengthy geometric-model-building processes that may take days to weeks. Moreover, it mitigates the risk of model failure and reduces engineering hours, making it a cost-effective and efficient solution.
|