Structural and electrical characterisation of ion-implanted strained silicon

The production of low resistance ultra-shallow junctions for e.g. source/drain extensions using low energy ion-implantation will be required for future CIVICS devices [H. Wakabayashi, M. Ueki, M. Narihiro, T. Fukai, N. Ikezawa, T. Matsuda, K. Yoshida, K. Takeuchi. Y. Ochiai, T. Mogami, T. Kunio, Trans. Electron Devices 49 (2002) 89-94]. This architecture will require implants which demonstrate high electrical activation and nm range depth profiles. We investigate the properties of Sb implants in tensile strained silicon due to their potential to satisfy these criteria and the mobility enhancements associated with tensile strained silicon. Low energy (in this case 2 keV) implants coupled with Sb's large atomic radius are capable of providing similar to 10 run implant depths. In addition to this. Sb demonstrates higher electrical activation in the presence of tensile strain, when compared with the more traditional n-type dopant As [N.S. Bennett, N.E.B. Cowern, A.J. Smith, R.M. Gwilliam, B.J.Sealy, LO'Reilly, P.J. McNally. G. Cooke, H. Kheyrandish, Appl. Phys. Lett. 89(2006) 182122]. We now report on the initial results of an ongoing systematic study over a wide silicon tensile strain range (from 0.4% to 1.25% strain) in order to establish clear strain-related trends. Graded Si(1-x)Ge(x) virtual substrates (VS) with 0.1 23% (i.e. epsilon > 0.9%) we find clear evidence of tilt in the SiGe VS, which impacts on the quality of the strained Si. Additionally, stacking faults have been detected non-destructively in the higher strain samples (epsilon = 1.25%. VS = Si(0.7)Ge(0.3)) using SXRT in transmission mode. (C) 2008 Elsevier B.V. All rights reserved.