Statistics of indium bump height of focal plane detectors by MATLAB

Indium bump fabrication is a key step of infrared focal plane arrays (IRFPAs) process with flip-chip bonding between sensor chip and Si readout integrated circuits (ROICs), and indium bump height is an important factor of indium bump fabrication quality. The usual method for indium bump height statistics is manual observation of the randomly picked indium bump by microscope. However, it can't comprehensively reflect the true situation for the lack of enough samples. On the other hand, the subjectivity of manual observation makes the statistical results inaccurate. In this paper, an improved method of the statistics of indium bump height was stated. First, the confocal laser scanning microscopy (CLSM) was used to scan the surface morphology of the indium bump arrays, then, MATLAB was used to work out the specific indium bump heights by analyzing the data CLSM scanned, when concerning the morphology's influence on the calculation of indium bumps. A real statistic of 1616 format ROIC was done, and the result was better than manual observation. It can provide indium height data with great accuracy for evaluating the indium fabrication quality by using this method.