Mechanisms for laser-induced functional damage to silicon charge-coupled imaging sensors

Abstract

We measured the functional degradation of silicon CCD photodetector arrays when subjected to Nd:YAG laser irradiation at 1.06 µm by 10-ns pulses. Operational tests such as dark leakage, point-spread function, and modulation transfer function were developed for testing individual pixels and applied to the testing of locally laser-damaged CCD arrays. Testing revealed that the primary failure mechanism was the spreading of the point-spread function in the direction of clocked charge motion that resulted from a decreased depth of potential wells within the laser-damaged spot. Lesser degradation was observed at pixels near the damaged spot that were served by clock lines that traversed the damage spot. This damage behavior was correlated with decreased breakdown voltage and increased leakage current between adjacent clock lines. Subsequent morphological and TEM examination of similarly constructed chips indicated that laser heating of the polysilicon clock lines led to degradation of the adjacent isolation oxide between clock lines. Functional damage occurred at locations where two clock lines were very close to each other, and the thin oxide layer separating them was subjected to high temperatures that resulted from melting of the neighboring polysilicon.

Precision laser annealing of silicon devices for enhanced electro-optic performance

“…3(b). Note the sharp transition at 1.1 J/cm 2 , which agrees well with other published values for Si [3]. As an example of the power and utility of laser annealing consider the results of figure 4.…”

“…This is in contrast to single shot damage thresholds where surface damage always preceded electrical damage. Morphological damage preceding electrical damage has been observed before [2]; however, for CCDs electrical performance can degrade prior to the onset of surface damage [3]. For multi-shot investigation the experimental setup is configured to produce one shot every second up to 20 shots.…”

Damage Analysis of CCD Image Sensor Irradiated by Continuous Wave Laser

“…또한, 근적외선 대역의 레이저를 이용하면 공기 중의 산란이나 흡수가 비교 적 적어 먼 거리에서도 운용이 가능하다 [2,3] . 국내에서는 본 연구진이 CMOS 영상센서를 대상으 로 한 연구가 유일하며 [5] , 국외에서는 포토다이오드에 1064 nm 파장의 펄스 레이저를 조사하였을 때 나타나 는 응답지연과 표면손상에 대한 연구 [6] 와 CCD에 1064 nm 파장의 펄스 레이저를 조사하였을 때 전기적 특성 의 변화 및 LIDT(Laser-Induced Damage Threshold)에 대 하여 분석한 사례가 있다 [1,7] . 그러나 CCD 영상센서를 대상으로 연속발진 레이저에 의한 반응거동을 분석한 연구는 전무하다.…”

Analysis of the disturbance of remote aerial detector induced by laser

“…When the electrons accumulated in the capacitor reached a certain number, it will penetrate and overflow from the potential hill. Then the phenomenon of crosstalk will be appeared [7,8] . detecting precision, the detecting system must has a small field angle.…”