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Ferroelectric random access memory with high electric properties and high production yield realized by employing an AlO <sub/>x</sub> underlying layer of Pt bottom electrode for a La-doped lead zirconate titanate capacitor
摘要： Although ferroelectric random access memory (FRAM) has superior electric properties, its downside is that it has a relatively larger cell area in comparison other non-volatile memories. We tried to apply TiOx, and AlOx to an underlying layer (TiOx-UL, AlOx-UL) instead of our previously used Ti underlying layer (Ti-UL) for the La-doped lead zirconate titanate (PLZT) capacitor to obtain a high polarization value aiming to a lowering cell area. The failed bit ratio of the FRAM with TiOx-UL was found to be higher than that with AlOx-UL even though polarization values of the PLZT capacitor with both underlying layers are almost the same and much higher than that with Ti-UL. It is strongly suggested that the imprint induced in PLZT by charged defect is a main cause of bit failure by fail-bit analysis. X-ray diffraction and atomic force microscopy observations shows that charged defect density in PLZT over TiOx-UL is possibly higher than that in PLZT over AlOx-UL due to surface roughness of underlying layers.
关键词： FRAM,AlOx underlying layer,Ferroelectric random access memory,production yield,polarization,PLZT capacitor,TiOx underlying layer
更新于2025-09-23 15:21:21
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Controlled Oxidation of III-V Semiconductors for Photonic Devices
摘要： The oxidation of III-V semiconductors is a crucial technological process in the mass-volume manufacturing of (singlemode) Vertical-Cavity Surface-Emitting Lasers or in the fabrication of more-recently-demonstrated integrated photonic devices. To facilitate the deployment of VCSELs in their up-rising markets but also to sustain the above-mentioned emerging uses, the shape and size of the optical/electrical apertures resulting from the selective lateral oxidation of buried layers of aluminum-containing III-V semiconductors needs to be controlled with an ever-increasing accuracy and reliability. In this paper, we will review the recent experimental investigations and model developments we have carried out to analyse and describe in detail this oxidation process. In particular, we will show that its degree of anisotropy depends on the oxidation process conditions and that the detrimental shape distortion induced by this anisotropy may be mitigated by a careful design of the etched mesas used to enable the oxidation of the buried layers.
关键词： oxidation,VCSEL,waveguides,AlOx,anisotropy
更新于2025-09-12 10:27:22
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Anisotropic lateral oxidation of Al-III-V semiconductors: inverse problem and circular aperture fabrication
摘要： The lateral wet oxidation of aluminum-containing III-V-semiconductors is a technological process which converts a buried (thin) cristalline material into an amorphous insulator and, as such, tends to exhibit an anisotropic behavior. As a result, the shape of the interface between the semiconductor and the insulator, often referred as the oxide aperture, differs from the etched mesa contour from which the oxidation proceeds. This, in turn, complicates the design of the devices relying on this process especially when specific oxide patterns are needed. In this paper, we introduce a method based on a morphological dilatation to determine the shape of the mesas which will lead to a specific targetted contour upon an anisotropic oxidation over a modest extent. The approach is experimentally validated by demonstrating the fabrication of circular oxide apertures which are inherently difficult to make because of their high degree of symmetry but which also turn out to be of critical importance in obtaining efficient single-mode vertical-cavity surface-emittting lasers.
关键词： AlOx,oxidation,anisotropy,VCSEL
更新于2025-09-11 14:15:04