John Smythe

Depth profiling of dielectric SrTiO3 thin films by angle-resolved x-ray photoelectron spectroscopy

This letter reports the results from using angle-resolved x-ray photoelectron spectroscopy to nondestructively characterize ultrathin high-k SrTiO3 (STO) films. Results indicate that carbon is present in the STO film in the form of SrCO3 which is amorphous. SrCO3 concentration varies as a function of its position in the film as measured by the take-off angle (TOA). For films annealed at 650°C, the C 1s, O 1s, and Sr 3d photoelectron transitions indicate a significant reduction in the carbonate. There is Sr enrichment on the surface, and the composition gradually converges to stoichiometric STO with Sr∕Ti∼1 at higher TOA.

Shallow trench isolation liners and their role in reducing lattice strains

Three spin-on dielectric (SOD) shallow trench isolation (STI) structures were studied: nitride liner, nitride liner with anisotropic amorphous silicon (a-Si) bottom fill, and nitride liner with thin conformal a-Si. All samples received the same SOD material conditions and final thermal oxidation. Convergent beam electron diffraction determined the induced STI strain and has been shown to accurately measure strain on 60nm active areas. The results revealed effects that the liners have in balancing stress induced by volume shrinkage of the SOD. The conformal a-Si liner decreased the shear force that causes dislocations that form at the bottom corners of STI structures.