Dopant influence on polysilicon capacitor oxide failure
In this work, we investigate polysilicon capacitor oxide defectivity as a function of dopant contamination in a 0.5 /spl mu/m mixed signal process. Experiments show that shallow n and p type dopant implants, used to mimic a cross contamination problem discovered in a PECVD cluster tool, can significantly degrade oxide integrity. Various possible mechanisms of the increased defectivity are discussed.
Polyoxide thinning limitation and superior ONO interpoly dielectric for nonvolatile memory devices
Results obtained from a study on thin interpoly dielectrics, especially for nonvolatile memories with stacked-gate structures, are presented. First, the key factors which dominate the leakage current in polyoxide are reviewed, and intrinsic limitations in thinner polyoxide for device applications are investigated considering defect densities and edge leakage current. Second, the ONO (oxide/nitride/oxide) structure which overcomes polyoxide-thinning limitations is described. This stacked film reveals superior electric-field strength due to the inherent electron-trapping-assisted process. UV erase characteristics for EPROM cells with ONO structure are discussed. The slower erasing speed for EPROM cells with ONO interpoly dielectric is due to the decrease in photocurrent flow from a floating gate to a control gate. >
Evaluation of buckling load and dynamic performance of steel shear wall retrofitted with strips made of shape memory alloy
One of the most imperfections of the steel shear wall is out of plane displacements that cause severe damage in both structural and non-structural elements. In this paper, the effects of shape-memory alloys on steel shear walls are investigated. First, a numerical analysis using the finite element method in ABAQUS software has been carried out according to an experimental test. The results of the numerical analysis have been verified with experimental results. Next, shape-memory alloy fibers have been added vertically and horizontally to various parts of the steel shear wall. The results show that retrofitting with the shape-memory alloy reduces the out-of-plane displacement of the steel shear wall under both cyclic and seismic loadings. Besides, the buckling load in the steel shear wall increases when it is retrofitted with the shape-memory alloy. Also, the total out-of-plane movement (accumulated absolute displacements) of the steel shear wall and non-structural damage are controlled by the characteristic of a shape-memory alloy material called “super-elastic”.