Regensburg 2000 – scientific programme

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DS: Dünne Schichten

DS 33: Schichtcharakterisierung II

DS 33.4: Fachvortrag

Thursday, March 30, 2000, 10:15–10:30, H32

Improved Sputter Depth Profiling of WSix Layers on Si — •Andriy Goryachko, Dietmar Krueger, and Rainer Kurps — Institut fuer Halbleiterphysik (IHP), Walter-Korsing-Str. 2, 15230, Frankfurt (Oder)

Sputter depth profiling of WSix / Poly-Si structures is required in advanced Si based CMOS technologies, e.g., for sub-0.25 micron DRAM circuits. Ion beam induced artifacts, such as knock-on effects, preferential sputtering, and surface roughening often complicate the use of ion beams for failure analysis and technology optimization.

We used low-angle / low-energy ion sputtering and beveling techniques to improve compositional characterization of WSix layers. Experimental results for depth profiling using Ar, Xe, Cs primary beams with Auger electron spectroscopy (AES), X-ray induced photoelectron spectroscopy (XPS), and time - of - fligth secondary ion mass spectrometry (ToF-SIMS) are presented. Under standard measurement conditions, preferential sputtering strongly depletes the WSix surface of Si in comparison to the true composition. The improved analysis conditions used in this work reduce the ion beam induced alteration of chemical composition. We have also successfully applied sample rotation during sputtering to improve the depth resolution of the measurements. A new method for further improvement, namely hemispherically integrated ion sputtering is proposed.