Back-side De-processing using CMP for bulk silicon 40-nm graphics processors
A back-side de-processing process by chemical mechanical polishing (CMP) is developed. The process has been optimized to produce repeatable results. The process is capable of exposing the circuitry of the die uniformly and is able to target more than one area for units with multiple defect locations; front-side de-processing process has difficulty achieving the same results due to the unevenness of the die
Backside failure analysis and case studies for Cu/low k technology
In this work, failure analysis (FA) challenges and new failure modes for devices of copper technology, especially for circuit-under-pad (CUP) devices are presented. Backside FA techniques including backside sample preparation, backside defect localization, backside physical analysis with both deprocessing and cross section analysis have been developed and applied to Cu/low k technology. For backside FA deprocessing, we present wet chemical etching, reactive ion etching (RIE), parallel polishing, chemical mechanical polishing (CMP) and combination of these techniques. For the backside FA cross-section analysis of copper/low k samples, focused ion beam (FIB) techniques that have been developed and studied are addressed. In addition, detailed characterization of backside silicon thinning using TMAH wet chemicals is presented.
Refinement of crystal structure parameters using convergent‐beam electron diffraction: the low‐temperature phase of SrTiO3
The method to refine crystal structure parameters (atom positions and Debye–Waller factors) using convergent-beam electron diffraction (CBED), which is applicable to crystal structure analysis of a small specimen area down to a few nm in diameter, is studied. The line profiles of higher-order Laue-zone reflections are recorded using imaging plates. Theoretical intensities are calculated based on the dynamical theory of electron diffraction with the aid of the generalized Bethe approximation to shorten calculation time. The structural parameters are determined by fitting the experimental profiles with the theoretical ones using a nonlinear least-squares method. The present method has been applied to the low-temperature phase of SrTiO3. The structural parameter or the rotation angle of the oxygen octahedron has been determined to be \varphi = 1.12 (4)°, which shows good agreement with that obtained from electron spin resonance experiments.