Dehydrogenation-enhanced large strain (∼1.6%) in Si pillars covered by Si3N4 stress liners

High-strain Si-pillars are desirable for achieving high-speed three-dimensional transistors. The effects of postannealing (400-1150C) on strain-enhancement in Si-pillars covered with Si₃N₄ stress-liners are investigated. Before annealing, the Si₃N ₄ stress-liners induce strain in Si, where the direction of strain, which can be compressive or tensile, depends on the Si₃N₄ deposition parameters. After postannealing (800C), the strain becomes highly compressive, because of dehydrogenation-induced structural relaxation in Si ₃N₄ films. Consequently, compressive strains (1.6) are induced in the 200-nm-thick Si-pillars covered in 200-nm-thick Si ₃N₄ films after high temperature postannealing (1000-1150C). This strain-enhancement technique is useful for the realization of advanced high-speed three-dimensional transistors.