A method to simulate fluorine outgas and Al bond pad corrosion in wafer fab

Abstract

This paper describes a wafer-level Reliability test methodology for Al bond pad corrosion due to long term wafer storage even in a controlled environment, such as N2 cabinet or vacuum packaged wafer box. The sensitivity of such a reliability test very much depends on how well it captures fluorine contaminant and moisture, the two key determinants of Al pad corrosion. Our test methodology is able to do so by a simple improvised solution to the experimental setup involving a wafer-box which contains quartz-boat mount test wafers. An array of small holes were drilled in the top cover lid of the box so that it can allow moisture from the test chamber to diffuse into the container and at the same time, still trap fluorine outgassed from the test wafer. The accelerated test methodology was successfully used to simulate, in laboratory time-scales, Al pad corrosion due to F-outgas from the pad sidewall polymer residue.