X-ray investigation of buried SiGe islands for devices with strain-enhanced mobility

Hrauda, N.; Nanver, L. K.; Stangl, J.; Schmidt, O. G.; Zhang, J. J.; Rehman-Khan, A.; Jovanovich, V.; Stoffel, M.; Bauer, G.

doi:10.1116/1.3056178

Journal Article

X-ray investigation of buried SiGe islands for devices with strain-enhanced mobility

Hrauda, N. (Corresponding author)Extern* ; Zhang, J. J. ; Stangl, J. ; Rehman-Khan, A. ; Bauer, G. ; Stoffel, M. ; Schmidt, O. G. ; Jovanovich, V. ; Nanver, L. K. ; DESY

2009
Inst. New York, NY

International Conference on Nanoscience and Technology, ICN+T 2008, Keystone, Colorado /USA, 20 Jul 2008 - 25 Jul 2008 Journal of vacuum science & technology / B 27, 912-918 (2009) [10.1116/1.3056178]

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Please use a persistent id in citations: doi:10.1116/1.3056178 doi:10.3204/PHPPUBDB-9724

Abstract: In this work self-organized SiGe islands are used as stressors for Si capping layers, which later act as carrier channels in field effect transistors. To be able to address individual islands and to obtain a sufficiently narrow distribution of their properties, the SiGe islands are grown by molecular beam epitaxy on prepatterned Si substrates, with a regular two-dimensional array of pits. This combination of lithographic patterning and self-assembled island growth combines the advantages of both approaches and leads to very homogeneous island shape, size, and chemical composition. For processing, 4in. wafers are used, and fields with pit periods between 600 and 1000nm are defined by optical lithography. After growth of a Si buffer layer several monolayers of Ge are deposited, leading to island formation (dome or barn shaped) in the pits. Subsequent Si capping is performed at a low substrate temperature of 300°C to avoid intermixing and shape changes of the buried islands. The Ge distribution in the buried islands and the strain distribution in the islands and the surrounding Si matrix are assessed by x-ray diffraction experiments, combined with three-dimensional model simulations using finite elements. Tensile strain values in the Si cap up to $8×10^{−3}$ can be achieved using this approach, which is difficult to achieve using other methods without introduction of dislocations.

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