Application of image processing to wafer probe mark area calculation

This paper presents an image processing approach that calculates the probe mark area on semiconductor wafer pads. The electrical characteristics of the chip pad must be tested using a probing needle before wire-bonding to the wafer. However, this test leaves probe marks on the pad. A large probe mark area results in poor adhesion forces at the bond ball of the pad, thus leading to undesirable products. Traditionally, given the difficulty of calculating the area of the irregular probe mark, probe mark area calculations were substituted by calculating the area of the oval that is manually drawn to cover the probe mark area. Nevertheless, this method is inaccurate, and the results varied from person to person. In this paper, we present an imaging processing approach to calculate the probe mark area utilizing high magnification microscopes to capture probe mark images. Our approach is faster and more accurate compared to traditional methods.