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A multiscale modeling platform that supports the “virtual” qualification of commercial-off-the-shelf parts is presented. The multiscale approach is divided into two modules. The first module generates information related to the bipolar junction transistor gain degradation that is a function of fabrication process, operational, and environmental inputs. The second uses this information as inputs for radiation-enabled circuit simulations. The prototype platform described in this paper estimates the total ionizing dose and dose rate responses of linear bipolar integrated circuits for different families of components. The simulation and experimental results show good correlation and suggest this platform to be a complementary tool within the radiation-hardness assurance flow. The platform may reduce some of the costly reliance on testing for all systems. [ABSTRACT FROM AUTHOR]

In this work, a generalized yield criterion that captures non-Schmid effects is proposed and implemented into a finite element crystal plasticity model to simulate plastic deformation of single and polycrystals. The parameters required for the constitutive formulation were calibrated to deformation experiments on single crystals. This model is used to investigate the effects of non-Schmid effects on the predictions of the stress-strain response and texture evolution in body-centered-cubic (bcc) metals. The non-Schmid contributions are required to accurately predict the stress-strain response of single crystals, and the concomitant non-associativity of the flow also increases the tendency of localization in polycrystal deformations. [ABSTRACT FROM AUTHOR]

The interplay between deformation and microstructure evolution can be strong and is the basis of a large majority of thermomechanical processing techniques for metals. We present simulations of this interplay, using a sharp-interface front tracking model for grain growth and a finite-element polycrystal plasticity model of deformation that includes anisotropic linear elasticity. The two approaches are iteratively coupled, so that grain growth affects the deformation behavior, and vice versa. Analyses of both purely elastic and of elastic-plastic materials are presented through coupled simulations of static loading of model polycrystalline micro- structures. In the elastic case, stored elastic energies can reach relatively high values, and the mechanical driving force can locally exceed the curvature driving force, causing boundaries to assume noncompact (rippled) shapes. These large driving forces also serve to accelerate the grain growth process. In the elastic-plastic case, under relatively low strains, plasticity provides a stress relief mechanism that prohibits the generation of large stored elastic energies; thus, substantial deviations from compact interface morphologies were not observed, and growth kinetics did not accelerate substantially. [ABSTRACT FROM AUTHOR]

Mechanical testing of thin fills for MEMS has progressed from a developmental stage to a point where validated techniques are used to study the behavior of devices and materials at a very fine scale. Tensile data coveting a range of sizes and test techniques have been analyzed to examine the distribution of defects that would be responsible for the observed fracture strengths. For each sample, a critical defect size was calculated based on a published fracture toughness and a half-circular surface crack fracture toughness model. For polysilicon produced using the SUMMiT V process in the period 1998-1999, the calculated mean defect size was 115 nm. For polysilicon produced using the MUMPS process, the calculated mean defect size was 389 nm. [ABSTRACT FROM AUTHOR]