Stress and impurities in electroplated copper

Changes in the as-deposited stress state of electroplated Cu layers as a function of plating current and additive concentrations are shown to be directly linked to the incorporation of impurities in the layer. A compressive trend is seen for both decreasing current and increasing additive concentrations due to an increasing incorporation rate A desorption of these impurities from the layer, accompanied by a stress reduction, occurs at just over 100 degreesC during a thermal cycle independent of the deposition parameters.