SIDAM · Investigation of Si wafer damage in manufacturing processes

Wafer handling in semiconductor manufacturing introduces microcracks at the wafer edge. During thermal processing, some of these grow into slip bands; on rapid thermal processing some of these grow into cracks, shattering the wafer and disrupting manufacture. Dense slip bands also lead to yield loss by locally increasing diffusion rates. Breakage losses alone were of the order of €2.5M p.a. for a single fab line at the 90 nm node. Microcracks and slip bands are visible through X-ray Diffraction Imaging (XRDI); but it is unknown which of the many defects imaged are those that will result in yield loss and breakage. We aim to discover how to derive quantitative, predictive information from XRDI, enabling a breakthrough metrology of wafer inspection. The project will comprise quantification of the XRDI images, modelling of the stresses introduced by the controlled defects, modelling the influence of thermal gradients in RTA upon the defects, and experimental confirmation of the conclusions. The outcome of this research will offer a competitive advantage at several levels to those members of the European Semiconductor Industry who agree to join the Industrial Advisory Board. European wafer manufacturers will have early access to a technique that reveals the nature of the defects in the wafers and their relevance to semiconductor device fabrication. This could provide Europe with a competitive advantage in the development of both 450mm and thin silicon wafers. European wafer and equipment manufacturers will have early access to a unique and specifically developed body of open knowledge to aid them in the evaluation of risk of breakage during their processes. They will have a choice of access to off-line characterization of defects by XRDI at ANKA or an in-line wafer inspection tool commercialized by Bede plc. The knowledge and tools developed will contribute to maintaining Europe's leading position in semiconductor x-ray metrology.