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The paper investigates the dependence of the flow stress σ of ultra‐high‐purity molybdenum single crystals on temperature T, strain rate, and crystallographic orientation of the crystal axis. The cyclic‐deformation technique developed by Mughrabi and Ackermann allowed a complete set of flow‐stress data (covering the temperature range 125 to 460 K at 15 different shear strain rates, varying from 5.9 × 10—7 to 1.7 × 10—3 s—1) to be obtained on one and the same specimen. The two crystals investigated, with Schmid factors μ{110} = 0.50 and μ{112} = 0.43, or μ{110} = 0.40 and μ{110} = 0.43, respectively, had residual resistivity ratios exceeding 2.5 × 105, the main impurity being W. The data are in excellent agreement with the theory of flow‐stress control by kink‐pair formation and kink migration. It is shown that for both orientations the elementary glide steps of the a0 〈111〉/2 screw dislocations controlling the flow stress occur on {112} planes. The formation energy of a pair of isolated kinks on a {112} plane is 1.27 eV, in perfect agreement with the activation energy of the so‐called γ‐relaxation as determined by internal‐friction measurements. The apparent kink mass and the kink diffusivity could be determined, too. The present results leave no doubt that the “hump” observed in the σ–T relationship of high‐purity b.c.c. metals is due neither to a change in the glide mechanism nor to a special form of the Peierls potential but is a natural consequence of the dependence of the kink‐pair formation enthalpy on the resolved shear stress.

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The influence of the SIN cap-layer deposition process including different pre-clean treatments on the electromigration (EM) and stressvoiding (SV) behavior of copper dual damascene metalli:rations has been studied. A rcmarkable trade-off between the EM and SV performance was revealed depcnding primarily on the pre-treatment beforc cap-layer deposition rather than the deposition process itself On the one hand an "aggressive" pre-treatment yields improved CdSiN-interface properties with higher electromigration failure times and activation energies (1.22 ... 1.26eV). On the other hand these pre-cleans were found to provoke stressvoiding failures because of the recovery of crystal defects induced in the hulk copper during the plasma treatment. The degree of microstructural damage and hence thc SV susceptibility was found to increase with the preclean intensity. In contrast, no SV risk is related to "less aggressive" pre-clean treatments since they are influencing only the copper surface. The crystal structure of the bulk remains unaffected and hence -in absence of any crystal recovery -no vacancies will be generated. However, these pre-cleans result in significantly lower EM performance with smaller failure times and activation energies (1.03 ... 1.06eV).The results illustrate the need to adjust the SIN cap-layer process parameters with respect to both EM & SV performance to meet the overall reliability requirements for these wear-out mechanisms: at the same time.

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