Articles you may be interested inThe effects of the stress dependence of atomic diffusivity on stress evolution due to electromigration Stress evolution during stress migration and electromigration in passivated interconnect lines AIP Conf. Proc. 305, 231 (1994); 10.1063/1.45694 Microstructure based statistical model of electromigration damage in confined line metallizations in the presence of thermally induced stressesElectromigration is an important concern in very large scale integrated circuits. In narrow, conilned metal interconnects used at the chip level, the electromigration flux is resisted by the evolution of mechanical stresses in the interconnects. Solutions for the differential equation governing the evolution of back stresses are presented for several representative cases, and the solutions are discussed in the light of experimental as well as theoretical developments from the literature.

The S100A2 protein is an important regulator of keratinocyte differentiation, but its role in wound healing remains unknown. We establish epithelial-specific S100A2 transgenic (TG) mice and study its role in wound repair using punch biopsy wounding assays. In line with the observed increase in proliferation and migration of S100A2-depleted human keratinocytes, mice expressing human S100A2 exhibit delayed cutaneous wound repair. This was accompanied by the reduction of re-epithelialization as well as a slow, attenuated response of Mcp1, Il6, Il1β, Cox2, and Tnf mRNA expression in the early phase. We also observed delayed Vegfa mRNA induction, a delayed enhancement of the Tgfβ1-mediated alpha smooth muscle actin (α-Sma) axis and a differential expression of collagen type 1 and 3. The stress-activated p53 tumor suppressor protein plays an important role in cutaneous wound healing and is an S100A2 inducer. Notably, S100A2 complexes with p53, potentiates p53-mediated transcription and increases p53 expression both transcriptionally and posttranscriptionally. Consistent with a role of p53 in repressing NF-κB-mediated transcriptional activation, S100A2 enhanced p53-mediated promoter suppression of Cox2, an early inducible NF-κB target gene upon wound injury. Our study thus supports a model in which the p53-S100A2 positive feedback loop regulates wound repair process.

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Load relaxation testing has been demonstrated to be useful for characterizing the time dependent plastic properties of metals. However, for testing of small material volumes, such as thin film metallizations, thin films, and contact surfaces, conventional load relaxation techniques cannot be used. For such applications an indentation test offers an attractive means for obtaining data necessary for materials characterization. This work shows that an indentation load relaxation test is experimentally feasible for thin film testing. Experiments on brass and beryllium copper samples with or without a gold/nickel plating illustrate different relaxation properties of the substrates and the surface layers. Furthermore, results of experiments on some fcc metals suggest rather simple relations between the conventional uniaxial load relaxation (LR) test and the indentation load relaxation (ILR) test.

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Results from indentation load relaxation (ILR) tests on thin film-substrate systems are reported.In the case of a 1 pum aluminum film on silicon, the data can be interpreted as reflecting both the properties of the film and the interface between film and substrate.Data from a 3 Um TiN film on 304 SS are believed to reflect the combined behavior of the film and substrate.

In this paper a miniaturized mechanical testing system designed for multiple testing modes is described. The main testing modes include (1) constant displacement rate testing in uniaxial tensile, compressive, and cyclic loading; (2) load relaxation testing; and (3) indentation hardness testing with a controlled displacement rate or displacement (load relaxation) with an indentation probe size as small as a few micrometers in diameter. The system, originally developed for testing materials and interconnecting structures for microelectronic components, is designed so that tests in different modes can be performed with only minor modifications. For room temperature testing, the temperature stability of the system is better than 0.1°C. The maximum loading capacity and displacement range are ∼ 100 N and 5 cm, respectively, and the smallest displacements that can be controlled are ∼ 0.01 µm. The capabilities of the testing system in different testing modes are demonstrated. Tensile and load relaxation test results of thin wires (<0.1 mm in diameter) with an accuracy comparable to bulk specimen results are presented. Also reported are results from indentation load relaxation tests with indentation depths applicable to irradiated material testing. Correlations between the mechanical properties of miniaturized specimens and bulk properties are discussed.