Electrical Characterization of the Backside Interface on BSI Global Shutter Pixels with Tungsten-Shield Test Structures on CDTI Process

A new methodology is presented using well known electrical characterization techniques on dedicated single devices in order to investigate backside interface contribution to the measured pixel dark current in BSI CMOS image sensors technologies. Extractions of interface states and charges within the dielectric densities are achieved. The results show that, in our case, the density of state is not directly the source of dark current excursions. The quality of the passivation of the backside interface appears to be the key factor. Thanks to the presented new test structures, it has been demonstrated that the backside interface contribution to dark current can be investigated separately from other sources of dark current, such as the frontside interface, DTI (deep trench isolation), etc

Noise as a characterization tool for reliability under illumination of transfer gate transistor for image sensors applications

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Etude de la fiabilité sous éclairement des transistors spécifiques aux applications capteurs d'images à pixels actifs

GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

A comparative mismatch study of the 20nm Gate-Last and 28nm Gate-First bulk CMOS technologies

International audienceIn this work the threshold voltage (Vt), the current gain factor (β), and the drain current (ID) mismatch trends for 20 nm Gate-Last bulk CMOS technology integrating High-k/metal gate are investigated. The reported results indicate that the high k/metal Gate-Last technology exhibits a reduced metal gate granularity contribution to the Vt mismatch and good performance in terms of the β mismatch. This study further demonstrates that the ID variability mainly depends on the mismatch trends of Vt and β, and on the contributions of the transconductance divided by the drain current (Gm/ID) and the source drain series resistance (Rsd) terms. The 20 nm Gate-Last technology exhibits significant improvement in the Vt and β mismatch performance as compared to the 28 nm Gate-First counterpart. The evolution of the Vt and β mismatch parameters, iAΔVt and iAΔβ/β, is further analyzed as a function of the electrical oxide thickness EOT (Tox) along the technology nodes from 90 nm to 20 nm. A clear trend towards a reduction of the y-axis intercept (i.e. offset) of the linear plot of iAΔVt as a function of EOT is observed starting at the 28 nm Gate-First technology, with the offset approaching zero for the 20 nm Gate-Last technology node. This observation point out a considerable decrease of the gate material contribution to mismatch performances

Mismatch trends in 20nm gate-last bulk CMOS technology

session posterInternational audienceIn this work Vt and β mismatch for the 20 nm Gate-last bulk CMOS technology are investigated for the first time. Our results indicate that the 20 nm Gate-last technology exhibits significant improvement in the Vt and β mismatch performance as compared to the 28 nm Gate-first counterpart. Furthermore, the evolution of the Vt and β mismatch parameters, iA ΔVt and iA Δβ/β , is analyzed as a function of EOT (Tox) from the 90 nm technology node down to the 20 nm technology node. A clear trend towards a reduction of the y-axis intercept (i.e. offset) of the linear plot iA ΔVt vs EOT is observed from the 28 nm Gate-first technology, with such offset approaching zero for the 20 nm Gate-last technology node. This indicates evidence of a huge decrease in the mismatch contribution of the gate material

The Finite Element Method as applied to the calculation of the quantum efficiency in optoelectronic imaging devices

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