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. >
Experimental study on bond behavior between high-strength grout and deformed steel bars
Abstract Engineers use high-strength grout to connect precast concrete members for its low shrinkage and good fluidity. This paper designed 87 central pull-out specimens using the control variable method to investigate the influence of factors on the rebar-grout bond property such as compressive strength, steel grade, bar diameter, transverse stirrups, and bond length. The test result showed that improving grout compressive strength (85.8 MPa–122.7 MPa) cannot improve the bond strength, which was different from the previous conclusions of concrete pull-out tests. Simplified formulas were presented for calculating the characteristic values of bond strength, residual strength, peak slip, and relative slip of load-holding platform based on parameter analysis. Then, a constitutive model was proposed to predict the full-range bond stress-slip curve of high-strength grout and steel bar specimens from bearing to failure. Finally, FEA models were established to evaluate the applicability and accuracy of the constitutive model.