Directly electroplated microstructure

Structures have been electroplated directly to metal (Al) pads on Si wafers using only the metal pad geometry to define the position and shape of the electroplated pad. No further processing steps are required after the electroplating. These pads have been used to form the sensing elements in an adhesive bond degradation sensor. Other uses could include the electroplating of high density materials to increase inertial/accelerometer sensor mass for higher sensitivity. The electroplating has been performed on Al pads formed in a CMOS compatible process on whole Si wafers. Multiple 'bus bars' connected to different sensor pads have been used to simultaneously electroplate structures with different heights. Both zincating and evaporation of a Cu seed layer on the Si substrate followed by electroplating have been investigated to determine the parameters to achieve optimum Cu cover and the best adhesion of the electroplated Cu to the Al/wafer. This involved the development of a test to measure the adhesion of 100 micrometer X 100 micrometer electroplated Cu studs on a silicon wafer.