Nanoscale Investigation of Piezo and Leakage Defects in SBT Film by SPM(Special Issue on Nonvolatile Memories)

概要

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Surface morphology and piezo response on SBT films were simultaneously measured by scanning probe microscopy. In a sample that had many short-circuited capacitor pads, some curious structures were observed on the SBT film surface. The piezo image partially did not correspond with the AFM image. Some specific grains were revealed to be piezo defects. Also observed were some smaller grains with flat surface, which showed good ferroelectricity. Next, we carried out simultaneous measurements of surface morphology and leakage current. The scanning at an intentionally high voltage was repeated until the leakage points were found. We found the leakage points, which were on some large grains, not at grain boundaries or on the flat smaller grains. In another SBT film derived from an unrefined source, many ferroelectric defects were observed despite there being no curious structures on the surface. Purity has an important bearing on the ability to avoid these defects. Thus, these nanoscopic investigations would greatly facilitate understanding of the mechanisms responsible for problems and enable optimization of the process conditions in device fabrication.
社団法人電子情報通信学会の論文
2001-06-01