Wafer curvature was used to study the thermal-mechanical behavior of 1-mu m Cu thin films capped with a 100-nm-thick Si_3N_4 layer. These films were grown with either a Ta or a Si_3N_4 underlayer. Films on Si_3N_4 that were exposed to oxygen at the film/capping layer interface or at the center of the copper layer exhibited Bauschinger-like yielding at low stress. Stacks deposited under continuous vacuum, with a Ta underlayer, with carbon exposure at the upper surface of the copper film, or with oxygen exposure of only the underlayer did not demonstrate the anomalous yielding. Preferential diffusion of oxygen into copper grain boundaries or interfaces is the likely cause of the early yield behavior. Possible mechanisms include an increase in interface adhesion due to the presence of oxygen in solution and diffusion-induced dislocation glide as an additional driving force for dislocation motion at low applied stress.
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机译：利用晶圆曲率研究了1 μ m Cu薄膜的热力学行为，并覆盖了100 nm厚的Si_3N_4层。这些薄膜是用 Ta 或 Si_3N_4 底层生长的。在薄膜/封盖层界面或铜层中心暴露于氧气的Si_3N_4上的薄膜在低应力下表现出类似Bauschinger的屈服。在连续真空下沉积的烟囱，具有Ta底层，在铜膜的上表面暴露碳，或仅在底层暴露的氧气，没有表现出异常的屈服。氧优先扩散到铜晶界或界面中是早期屈服行为的可能原因。可能的机制包括由于溶液中存在氧而导致的界面粘附力增加，以及扩散诱导的位错滑移作为在低施加应力下位错运动的额外驱动力。
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