Degradation of CMOS APS Image Sensors Induced by Total Ionizing Dose Radiation at Different Dose Rates and Biased Conditions

Abstract

The experiments of total ionizing dose radiation effects on CMOS APS image sensors at the dose rates of 50.0 and 0.2 rad(Si)/s were presented. The CMOS APS image sensors were manufactured using the standard <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$0.35 - \mu \hbox{m}$</tex></formula> CMOS technology that had a typical gate-oxide thickness of 7.0 nm. The samples were divided into two groups, with one group biased and the other unbiased during <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{60}{\rm Co}\gamma $</tex> </formula> irradiation. When the samples were exposed to the total dose of 200 krad(Si), only one investigated device was still exposed up to the highest total dose of 800 krad(Si), and functional failure was observed. The dark signal ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${K_{\rm D}}$</tex></formula> ), dark signal non-uniformity (DSNU), noise ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${V_{\rm N}}$</tex></formula> ), saturation output signal voltage ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${V_{\rm S}}$</tex></formula> ), and dynamic range (DR) versus the total doses were investigated. The tendency for <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$K_{\rm D}$</tex></formula> , DSNU, and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${V_{\rm N}}$</tex></formula> to increase at 50.0 rad(Si)/s is larger than that at 0.2 rad(Si)/s. The degradation mechanisms of CMOS APS image sensors were analyzed. The room temperature annealing tests were performed at 24 h, 48 h, and 168 h with different biased conditions after irradiation.