Regensburg 2007 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 11: Poster Session
DF 11.2: Poster
Donnerstag, 29. März 2007, 14:30–18:00, Poster C
X-Ray Diffraction Studies of PrO2/Si(111) — •Lars Boewer1, Joachim Wollschläger1, Thomas Weisemoeller1, Carsten Deiter1, Peter Zaumseil2, and Thomas Schroeder2 — 1Fachbereich Physik, Universität Osnabrück, Barbarastr. 7, 49076 Osnabrück Germany — 2IHP-Microelectronics, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany
Due to the progressive miniaturization of electronic devices and the problem of leakage current, the search for oxides with high dielectric constants has become very important.
PrO2 is a good candidate for Si(111) based technology due to its small lattice mismatch of 0.7% with respect to the Si substrate. However, PrO2 is not stable under UHV conditions, but it is known that Pr2O3 films can be transformed to PrO2 films by annealing in oxygen. Here we investigate Pr2O3 films of 5nm thickness deposited at 625∘C on Si(111) and annealed in oxygen at 300∘C and 700∘C, respectively. XRD and GIXRD studies were performed at beamlines W1 and BW2 at HASYLAB (DESY).
Comparing the obtained data with the lattice spacing of Pr2O3 and PrO2 shows that the entire film is apparently converted to PrO2, although the vertical lattice constant is increased with respect to bulk PrO2 is caused by lateral compression of the pseudomorphic PrO2 film. In addition analyzing the thickness of the crystalline part of the PrO2 films shows that the crystalline film annealed at 300∘C is thicker than the film annealed at 700∘C. This loss of crystalline PrO2 can probably be attributed to the formation of Pr silicate at the interface.