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HL: Halbleiterphysik

HL 23: Grenz- und Oberfl
ächen II

HL 23.4: Vortrag

Mittwoch, 29. März 2000, 16:45–17:00, H17

Concerted-Exchange Diffusion of Dopants — •Jarek Dabrowski and Hans-Joachim Müssig — Institute for Semiconductor Physics (IHP), Walter-Korsing-Str. 2, D-15230 Frankfurt (Oder), Germany

Dopant atoms can segregate to SiO₂/Si(001) interfaces, causing problems in manufacture of submicron devices. Diffusion is a key element of the segregation process. Since dopant atoms must find adsorption sites at the interface, the number of adsorption sites accessible to a dopant atom (i.e., also the sticking coefficient) depends on the lateral diffusion coefficient. In bulk Si, dopant atoms need the presence of native point defects in order to diffuse, because diffusion processes in which a dopant exchanges sites with a lattice Si atom (No-dqconcerted exchange No-dq) have high activation energies. However, SiO₂ is a good sink for Si interstitials and vacancies, and the defect-mediated diffusion may be suppressed near the interface. Our ab initio calculations show that the strain due to distortion of Si-O and Si-Si bonds at the interface assists diffusion along the concerted exchange path. The strain-enhanced concerted exchange diffusion may therefore account for the high sticking coefficient of P to SiO₂/Si(001) interfaces.