A Method of Estimating Indium Bump Integration Yield in Hybrid IRFPA of HgCdTe Photodiodes
Hybrid IRFPAs are comprised of photo detector array and readout integrated circuit (ROIC) made of different materials best suited for their purposes, interconnected by flip-chip bonding using indium bumps. Typically, array operability of >99.9 % is required in several high-end applications of IRFPAs. Therefore, one cannot afford any operability loss due to failure of bump connectivity. To ensure high yield of bump connectivity, some iteration in flip chip process is usually needed. This requires the correct estimation of the connectivity after all iterations, so that even the single unconnected pixel may be identified and corrected. In this paper, we demonstrate a reliable method of estimating the bump connectivity of the ROIC and HgCdTe photodiode array by prober level room temperature measurements. The charge integrated on the integration capacitor in various modes of operation has been used to estimate the connectivity. This method is useful for initial IRFPA technology development.
KeywordsIndium bump Infrared IRFPA HgCdTe Photodiode ROIC
Unable to display preview. Download preview PDF.
The authors want to thank Director SSPL, Dr. R. Muralidharan, for encouragement and support to carry out this work and for granting permission to publish it.
- 1.M. B. Reine, A. K. Sood, and T.J. Tredwell, Semiconductors and Semimetals, vol. 18, ch. 6, 19th eds. (Academic Publisher, New York, 1981).Google Scholar
- 2.A. Rogalski, Infrared Phys. and Tech., 54, 136 (2011).Google Scholar
- 4.J. L. Tissot, Infrared Phys. and Tech., 43, 223 (2002).Google Scholar
- 5.R. S. Saxena, R. K. Bhan, L. Sareen, R. Pal and R. K. Sharma, IR Physics and Technology, 54, 108 (2011).Google Scholar
- 6.Y. Tian, C. Liu, D. Hutt, B. Stevens, 2008 Electronic Components and Technology Conference, 2096 (2008).Google Scholar