Effect of a post-deposition anneal on Al2O3/Si interface properties

• Main Authors: Benick, J, Richter, A, Li, T.-T A, Grant, N E, McIntosh, K R, Ren, Y, Weber, K J, Hermle, M, Glunz, S W
• Format: Conference Proceeding
• Language: English
• Subjects: Aluminum oxide; Annealing; Capacitance-voltage characteristics; Passivation; Silicon; Temperature measurement
• ISSN: 0160-8371
• DOI: 10.1109/PVSC.2010.5614148

While Al 2 O 3 has been proven to provide an excellent level of surface passivation on all sorts of p-type doped silicon surfaces, the passivation mechanism of this layer and especially the influence of the post-deposition anneal on the Al 2 O 3 /Si interface properties is not yet completely understood. A great increase in the surface passivation is observed after a post-deposition anneal, i.e. a post-deposition anneal is mandatory to activate the surface passivation. Thus, the influence of this anneal on the interface properties, density of negative fixed charges Q f and density of interface traps D it , will be investigated and correlated to the measured minority carrier lifetime. In the case of plasma enhanced ALD, Q f is already high in the as-deposited state and the annealing process only has a minor effect on Q f (Q f increases by 20-50 %, depending on the annealing temperature). The D it however is strongly reduced by the post-deposition anneal, decreasing by two orders of magnitude. This large reduction in D it is a prerequisite for benefiting from the strong field effect induced by the high density of negative charges of the Al 2 O 3 .