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Effect of point defect injection on diffusion of boron in silicon and silicon-germanium in the presence of carbon

Effect of point defect injection on diffusion of boron in silicon and silicon-germanium in the presence of carbon
Effect of point defect injection on diffusion of boron in silicon and silicon-germanium in the presence of carbon
Boron diffusion in Si and strained SiGe with and without C was studied using point defect injection.Interstitial-, vacancy- and noninjection conditions were achieved by annealing Si capping layers which were either bare, with Si3N4 film or with Si3N4+SiO2 bilayers, respectively. Concentration profiles of B, Ge, and C were obtained using secondary-ion-mass spectrometry and diffusion coefficients of B in each type of matrix were extracted by computer simulation. Under inert annealing, we find that C strongly suppresses B diffusion in SiGe:C, but the effect of C is less strong in Si:C, particularly at high temperatures. In contrast, C only weakly suppresses B diffusion in both Si:C and SiGe:C under interstitial injection. For inert anneal conditions, C reduces the B diffusion coefficient in Si:C by factors of 4.2, 5.9, and 1.9 at 940, 1000, and 1050 °C respectively, whereas for interstitial injection the factors are 2.1, 1.3, and 1.1, respectively. The equivalent factors for SiGe:C are 8.4, 5.9, and 8.0 for inert anneal conditions and 2.2, 3.4, and 1.6 for interstitial injection conditions. The degree of B diffusion suppression achieved in both Si:C and SiGe:C is dependent on the level of C retained during annealing. Diffusion of C is shown to be faster in Si:C and hence less C is retained there after annealing than in SiGe:C. Interstitial injection is shown to strongly enhance C diffusion in both Si:C and SiGe:C and hence decreases the effectiveness of C for B diffusion suppression. These findings illustrate that the retarding effect of C on B diffusion in both Si:C and SiGe:C is strongly reduced when the anneal is carried out under conditions where interstitials are injected from the surface.
Diffusion, carbon, Si:C, SiGe:C, point defects, boron
0021-8979
113531
Karunaratne, M.S.A.
b1163151-8361-4ae9-bda1-ee1a216d50d2
Willoughby, A.F.
854f065f-d9bd-41ca-a89c-dff19b6eba3b
Bonar, J.M.
12d01a95-92f9-4aa1-bce0-c857451cbbfe
Zhang, J.
722d2564-f8ae-40f1-b1e1-07896b67a0d8
Ashburn, P.
68cef6b7-205b-47aa-9efb-f1f09f5c1038
Karunaratne, M.S.A.
b1163151-8361-4ae9-bda1-ee1a216d50d2
Willoughby, A.F.
854f065f-d9bd-41ca-a89c-dff19b6eba3b
Bonar, J.M.
12d01a95-92f9-4aa1-bce0-c857451cbbfe
Zhang, J.
722d2564-f8ae-40f1-b1e1-07896b67a0d8
Ashburn, P.
68cef6b7-205b-47aa-9efb-f1f09f5c1038

Karunaratne, M.S.A., Willoughby, A.F., Bonar, J.M., Zhang, J. and Ashburn, P. (2005) Effect of point defect injection on diffusion of boron in silicon and silicon-germanium in the presence of carbon. Journal of Applied Physics, 97 (11), 113531.

Record type: Article

Abstract

Boron diffusion in Si and strained SiGe with and without C was studied using point defect injection.Interstitial-, vacancy- and noninjection conditions were achieved by annealing Si capping layers which were either bare, with Si3N4 film or with Si3N4+SiO2 bilayers, respectively. Concentration profiles of B, Ge, and C were obtained using secondary-ion-mass spectrometry and diffusion coefficients of B in each type of matrix were extracted by computer simulation. Under inert annealing, we find that C strongly suppresses B diffusion in SiGe:C, but the effect of C is less strong in Si:C, particularly at high temperatures. In contrast, C only weakly suppresses B diffusion in both Si:C and SiGe:C under interstitial injection. For inert anneal conditions, C reduces the B diffusion coefficient in Si:C by factors of 4.2, 5.9, and 1.9 at 940, 1000, and 1050 °C respectively, whereas for interstitial injection the factors are 2.1, 1.3, and 1.1, respectively. The equivalent factors for SiGe:C are 8.4, 5.9, and 8.0 for inert anneal conditions and 2.2, 3.4, and 1.6 for interstitial injection conditions. The degree of B diffusion suppression achieved in both Si:C and SiGe:C is dependent on the level of C retained during annealing. Diffusion of C is shown to be faster in Si:C and hence less C is retained there after annealing than in SiGe:C. Interstitial injection is shown to strongly enhance C diffusion in both Si:C and SiGe:C and hence decreases the effectiveness of C for B diffusion suppression. These findings illustrate that the retarding effect of C on B diffusion in both Si:C and SiGe:C is strongly reduced when the anneal is carried out under conditions where interstitials are injected from the surface.

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Published date: 2005
Keywords: Diffusion, carbon, Si:C, SiGe:C, point defects, boron
Organisations: Nanoelectronics and Nanotechnology

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Local EPrints ID: 260854
URI: https://eprints.soton.ac.uk/id/eprint/260854
ISSN: 0021-8979
PURE UUID: 231b1bb1-cd9e-429f-899f-52f8dc8f5800

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Date deposited: 12 May 2005
Last modified: 19 Jul 2019 22:36

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