Study of Probe Contact Resistance Impact on Inline Testing with Different Bond Pad Design in BEOL

Inline electrical testing in a semiconductor fabrication line is a very common method to monitor the line performance and to be able to detect any issue for the tested wafers. This helps to detect the problems much earlier. Detecting issues earlier not only stops the affected wafer from processing further, but it would be able to highlight an upstream process issue stopping other incoming wafers. Fundamental issues like high probe contact resistance (CRES) during test affects the measurement data integrity of critical device parameters. This also impacts the learning cycles as well as mean time to detect process / drift issues. Extensive data collection and experiments were able to conclude that the presence of copper oxide is the root cause of high CRES. Adhesion to different constructs explains variations seen in different designs.