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Overview Of Scatterometry Applications In High Volume Silicon Manufacturing

A review of scatterometry technology and its relevance to high volume silicon manufacturing is presented. First, an introduction and history of the technology are provided, with the technology being broadly described in two parts known as the “forward” and “inverse” problems. In the forward problem, the scatterometry signature is acquired by some optical measurement. Both single wavelength, angle scanning and fixed angle, wavelength scanning approaches to the forward problem are described. In the inverse problem, the scatterometry signature is analyzed to determine dimensional parameters that are of interest for the application. Two common approaches to the inverse problem are summarized. The most common approach involves a direct comparison to a pre‐computed database of theoretically generated signatures. Another approach, often called a “real time” regression, uses optimization methods to compare the measured signature against modeled signatures dynamically. Strengths and weaknesses of each method are discussed. Finally, a review of scatterometry applications with high potential in mainstream volume manufacturing will be presented. In particular, the emphasis will be on lithography applications that are readily addressable from a technology perspective and compelling in terms of their value to reducing costs and increasing yields in the manufacturing process. The increasing role of scatterometry for integrated metrology applications, and limits of the technology as the silicon industry moves well into the sub‐100 nm regime, will also be discussed.