High Throughput Phase Mapping for Metrology Using Low-Loss EELS

The plasmon-loss region of the low-loss electron energy loss spectroscopy (EELS) contains chemical information similar to core-loss EELS; therefore it can be utilized as finger-printing elements. A high throughput phase mapping technique based on plasmon energy (Ep) is proposed. We have successfully applied this phase mapping technique into two case studies in our magnetic head manufacturer processes. This Ep phase mapping can be applied to not only the data storage but also semiconductor industries.

Extrinsic and Intrinsic Contributions to Plasmon Peaks in Solids

Intrinsic and extrinsic plasmons are defined and the contribution of each determined. It is shown that quantum interference between intrinsic and extrinsic satellites in X-ray photoelectron spectroscopy (XPS) as well as in Auger electron spectra (AES) does not occur for plasmon loss peaks higher than first order. Line widths in measured reflected electron energy loss spectra (EELS) are analysed by subtracting the Shirley background. Contrary to common understanding, extrinsic and intrinsic contributions by plasmon peaks can be experimentally distinguishable by comparison of line widths.

Investigation of phase separation in InGaN alloys by plasmon loss spectroscopy in a TEM

ABSTRACTPhase separation of InxGa1-xN alloys into Ga-rich and In-rich regions was observed by a number of research groups for samples grown with high indium content, x. Due to the radiation sensitivity of InGaN to beam damage by fast electrons, high-resolution imaging in transmission electron microscopy (TEM) or core-loss electron energy-loss spectroscopy (EELS) may lead to erroneous results. Low-loss EELS can yield spectra of the plasmon loss regions at much lower electron fluxes. Unfortunately, due to their delayed edge onset, the low energetic core losses of Ga and In partially overlap with the plasmon peaks, all of which shift with indium content.Here we demonstrate a method to quantify phase separation in InGaN thin films from the low-loss region in EELS by simultaneously fitting both plasmon and core losses over the energy range of 13-30eV. Phase separation is shown to lead to a broadening of the plasmon peak and the overlapping core losses, resulting in an unreliable determination of the indium concentration from analyzing the plasmon peak position alone if phase separation is present. For x=0.3 and x=0.59, the relative contributions of the binary compounds are negligibly small and indicate random alloys. For xnom.=0.62 we observed strong broadening, indicating phase separation.