Papers by Author: B. Yang

Abstract: Issues of ferroelectric high-density memories (>64Mb) indispensable for upcoming ubiquitous era have been on the cell integration less than 0.1um2 and reliabilities. Thus nanoscale control of microstructures of ferroelectric films with large switching polarization has been one of the issues to obtain the uniform electrical properties for realization of high-density memories. In this study the grain orientations and distributions of BT-based films by spin-on coatings were examined by EBSD (electron backscatter diffraction) technique. Ferroelectric domain characteristics by PFM (piezo-response force microscope) were also performed to study the dependence of reliabilities on the grain orientations and distributions. It is believed that understandings of the nucleation and growth mechanisms of the a- or b-axis oriented films during the thermal processes such as RTA and furnace annealing affecting on grain orientation and uniformity could be possible based on this experimental results.

Abstract: Issues of ferroelectric high-density memories (>64Mb) indispensable for upcoming ubiquitous era have been on the cell integration less than 0.1um2 and reliabilities. Thus nanoscale control of microstructures of ferroelectric films with large switching polarization has been one of the issues to obtain the uniform electrical properties for realization of high-density memories. In this study the grain orientations and distributions of BT-based films by spin-on coatings were examined by an electron backscatter diffraction (EBSD) technique. Ferroelectric domain characteristics by a piezoresponse force microscope (PFM) were also performed to study the dependence of reliabilities on the grain orientations and distributions.

Abstract: A diaphragm, the most important part of pressure sensor, was successfully fabricated by an electro-chemical etch-stop (ECES) technique. It was important to control the thickness of the diaphragm precisely. We compared characteristic results of diaphragms by electro-chemical etch-stop with those by time-control etch-stop (TCES). The 4 inch n-Epi/p-substrate with 16±1 ㎛ thickness was utilized because the thickness of the diaphragm fabricated by ECES is controlled by the thickness of Epi.. The etching of silicon wafer was carried out in the solution (25 wt% KOH) at 80°C, using 3 electrode system with potentiostat. Proper voltages were applied to etch p/n-type silicon wafer after determined open circuit potential (OCP) and passivation potential (PP) of n and p-type silicon, respectively. Thickness of diaphragms fabricated by ECES was controlled in the range of 16±1 ㎛ while that by TCES was in the range of 16.1±2 ㎛. The roughness of diaphragm was 52±5 Å. When the pressure of 50 kPa was applied on the pressure sensor using the diaphragm fabricated by ECES, the error rate was improved to ±10 ㎷. In the case of the error rate of pressure sensor using the diaphragm fabricated by TC was in the range of ±25 ㎷ under the same condition.