红外焦平面阵列盲元簇成因分析

Analysis on formation of bad pixel cluster in IRFPA

红外焦平面阵列中盲元簇的存在增加了系统盲元补偿算法的难度和复杂度。同时,基于算法处理的红外系统对盲元簇的要求更加严格,导致红外焦平面阵列的合格率大大降低。通过对大量红外焦平面阵列产品的测试,得到了盲元类别的统计结果:单个盲元、盲元对和盲元簇的盲元分别占盲元总数的60.8%、17.6%和21.6%。经分析,确定了盲元簇的几种主要成因:前工艺阶段的材料缺陷、光刻图形缺失、铟渣残留和铟柱缺陷;后工艺中的铟柱未连通、应力导致的芯片碎裂;可靠性试验诱发的缺陷暴露与扩大。研究结果表明,在探测器材料的筛选、铟柱制备技术、低应力的工艺和结构技术等方面做进一步的优化工作,可以降低盲元簇产生的几率,从而提高红外焦平面阵列的性能和成品率。

Bad pixel cluster in infrared focal plane array （IRFPA） increases difficulty and complexity of bad pixel correction algorithm. Meanwhile, software-based tracking and target recognition system are generally less tolerant of bad pixels, especially large bad pixel cluster, than a human user system. This reduces the amount of qualified IRFPAs. Statistical results of bad pixels were obtained through a lot of tests on IRFPA products. Single bad pixel, bad pixel pair and bad pixel cluster accounted for 60.8%, 17.6% and 21.6% of total bad pixels respectively. Causes of bad pixel cluster were confirmed through analysis and tests, which were material defects, pattern missing, indium residual, indium bump defects, non-contact pixels, crack and potential defects exposed in reliability tests. Screening test on detector material, better fabrication technology of indium bumps, low stress technical process and structure are important to reduce bad pixel cluster, which are conducive to improve the performance of IRFPA.