Residual stress measurement in thin films using the semi-destructive ring-core drilling method using Focused Ion Beam

In the present study, residual stress evaluation in thin films was achieved using a semi-destructive trench-cutting method. Focused Ion Beam (FIB) was employed to introduce the strain relief by ring-core milling, i.e. creating a trench around an "island". Either SEM or FIB imaging can be used to record sequences of images for strain change evaluation by Digital Image Correlation (DIC) analysis of micrographs. A regular array of shallow holes was drilled on a thin overlayer of Pt (∼100nm) deposited on to the film prior to patterning and trenching, in order to reduce the damage introduced by the ion beam during imaging and to assist the DIC strain evaluation by adding traceable markers. Finite Element (FE) simulation was also carried out to predict the curves for strain relief as a function of milling depth, and compared with the experimental measurements, which show good agreement with each other. An empirical mathematical description of the curves was proposed that allows efficient residual stress evaluation in thin solid films. © 2011 Published by Elsevier Ltd

Toxicity, Tunneling and Feeding Behavior of the Termite, Coptotermes vastator, in Sand Treated with Oil of the Physic Nut, Jatropha curcas

Oil of the physic nut, Jatropha curcas L. (Malpighiales: Euphorbiaceae), was evaluated in the laboratory for its barrier and repellent activity against the Philippine milk termite Coptotermes vastator Light (Isoptera: Rhinotermitidae). The study showed that J. curcas oil had anti-feeding effect, induced reduction in tunneling activity and increased mortality in C. vastator. Behavior of termites exposed to sand treated with J. curcas oil indicated that it is toxic or repellent to C. vastator. Toxicity and repellent thresholds, were higher than those reported for other naturally occurring compounds tested against the Formosan subterranean termite

Nanoindentation for reliability assessment of ULK films and interconnects structures

© 2012 Elsevier B.V. All rights reserved. The structural integrity of interconnect structures containing ultra-low-k (ULK) dielectrics is highly dependent on the mechanical properties of the porous dielectrics, e.g. fracture toughness elastic modulus and adhesion as well. Four-point-bending (FPB) and double-cantilever-beam (DCB) methods for the evaluation of fracture properties require out-of-fab sample preparation and testing. The reliable characterization of interfacial adhesion is important for in-line/at-line process development and control in microelectronics manufacturing. The ability to detect an out-of-spec or defective ULK film at an early process step could potentially save processing and materials cost. Therefore, the development of quick turnaround experimental methodologies for monitoring in-line/at-line mechanical stability of ULK films and ULK-containing interconnects is of great interest for semiconductor industry. This study presents two novel experimental approaches for the evaluation of interface adhesion and mechanical robustness of on-chip interconnects structures based on nanoindentation and nanoscratch, (a) wedge indentation and (b) bump assisted BEOL stability indentation (BABSI) tests, respectively. Wedge indentation tests on ULK films with increasing porosity show a decrease of adhesion values. Correspondingly, BABSI tests show increasing failure rates for Cu/ULK interconnect structures containing mechanically weaker dielectrics

A singular edge-based smoothed finite element method (ES-FEM) for bimaterial interface cracks

10.1007/s00466-009-0422-3Computational Mechanics452-3109-125CMME