Epitaxial engineered solutions for ITRS scaling roadblocks

This paper reviews the current and future roles of epitaxy in providing both process and materials solutions to the scaling roadblocks identified by ITRS2005. now widely accepted that we are in an “era of materials enabled device scaling” [International Technology Roadmap for Semiconductors, 2005 Edition, Front End Processing.] and that in addition to new materials for the gate stack, advanced substrates will also become increasingly important in the 21st Century. The Emerging Materials Committee has identified a range of issues such as mobility enhancement and thermal management [M. Bulsara, G. Celler, H. Huff, R. Standly, E. White, Solid State Technol. (2006).] which can be addressed by new “engineered” substrates that are now manufacturable thanks to combinations of advanced layer transfer and epitaxy processes. ed silicon has proved to be an invaluable performance booster due to the enhanced mobilities resulting from different forms of uniaxial and biaxial strain. SiGe epitaxy is the key process enabling technology for both process induced (local) strain and bulk (global) strain. Hybrid orientation technology (HOT), where (1 0 0) and (1 1 0) surfaces coexist on the same silicon substrate, is also an exciting development for boosting pMOS mobility. Several embodiments of this approach also exist and all require forms of epitaxial processing. ed layer transfer processes make it possible to engineer substrates in a variety of ways which were, until recently, unimaginable. Layer transfer is essential to hybrid orientation technology and also makes strained silicon extendable onto SOI to produce ultra thin body (UTB) strained SOI substrates suitable for fully depleted CMOS devices. ition to its role in strain processes and engineered substrates, the number of ‘in-process’ epitaxy stages is also increasing. BiCMOS and HBT epitaxy are established technologies, however, the requirement to reduce source/drain series resistance is driving the introduction of elevated structures grown using selective epitaxy. mary, innovative epitaxy processes are essential for meeting the performance requirements of next-generation technologies and also have a crucial role in engineered substrate manufacture.