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Title: Real-time monitoring and control of critical dimensions in Lithography.
Authors: YANG GENG
Keywords: lithography, critical dimension, uniformity, real-time control, bake-plate, ellipsometry
Issue Date: 27-Dec-2012
Citation: YANG GENG (2012-12-27). Real-time monitoring and control of critical dimensions in Lithography.. ScholarBank@NUS Repository.
Abstract: Lithography is a key enabler accounting for a third of IC manufacturing costs. Critical dimension (CD) is the most important variable in the lithography sequence affecting the speed of the circuit. Current approaches to CD control are primarily based on a run-to-run strategy due to a lack of in-situ sensors and control authority. In this thesis, we proposed an approach to conduct real-time CD monitoring and control. It is well-known that temperature has a direct effect on CD. First, a multi-zone programmable thermal processing system is developed, which is able to control the wafer temperature uniformity during the entire thermal cycle. Next, an in-situ ellipsometry system is established and integrated into the thermal process to measure the CD profile in real-time. Compared with the state of art in current semiconductor manufacturing based on a run-to-run strategy, the proposed real-time control system is capable to monitor and control the CD across wafer in real-time. Experimental results demonstrate that the real-time control system improves the across wafer CD uniformity more than 60% versus a run-to-run approach.
Appears in Collections:Ph.D Theses (Open)

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