In this paper we present process tool monitoring and matching using an interferometry technique. There are many types of interferometry techniques used for various process monitoring applications. We use a Coherent Gradient Sensing (CGS) interferometer which is self-referencing and enables high throughput measurements. Using this technique, we can quickly measure the topography of an entire wafer surface and obtain stress and displacement data from the topography measurement. For improved tool and chamber matching and reduced device failure, wafer stress measurements can be implemented as a regular tool or chamber monitoring test for either unpatterned or patterned wafers as a good criteria for improved process stability.
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Doug Anberg, David M. Owen, Jeffrey Mileham, Byoung-Ho Lee, Eric Bouche, "Process tool monitoring and matching using interferometry technique," Proc. SPIE 9778, Metrology, Inspection, and Process Control for Microlithography XXX, 977831 (8 March 2016);