2 research outputs found
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
Innovative electrical characterizations of CMOS image sensors using test structures
Dans un contexte trĂšs concurrentiel et riche dâinnovations, il est crucial de pouvoir Ă©valuer les performances des capteurs de maniĂšres prĂ©cises. Pour ce faire deux supports de caractĂ©risation sont envisageables : le capteur complet ou les structures de test. Sur le capteur complet sont extraits des paramĂštres dans un environnement et des conditions proches de lâapplication. Les structures de test, elles, permettent de ne sâintĂ©resser quâĂ une zone spĂ©cifique dâun pixel et de pouvoir Ă©tudier les phĂ©nomĂšnes physiques en jeu et dissocier les diffĂ©rentes contributions possibles Ă un paramĂštre pixel Ă©tudiĂ©. Une meilleure comprĂ©hension de ce mĂȘme paramĂštre extrait sur capteur complet est alors possible. De plus elles facilitent lâĂ©tude de diffĂ©rents essais de procĂ©dĂ©s en dĂ©but de dĂ©veloppement. Les travaux de cette thĂšse proposent de nouvelles mĂ©thodologies de mesure et de caractĂ©risation de paramĂštres sur structures de test complĂ©mentaires Ă ce qui se fait sur un capteur complet. Dans ce manuscrit sont dĂ©veloppĂ©es notamment de nouvelles structures de test afin dâĂ©tudier la contribution de lâinterface arriĂšre de pixels BSI au courant dâobscuritĂ©. Une nouvelle mĂ©thode dâextraction de potentiels est Ă©galement prĂ©sentĂ©e et permet lâextraction dâune multitude de potentiels dâintĂ©rĂȘts prĂ©sents dans les pixels. Enfin une nouvelle mĂ©thode dâextraction de la charge Ă saturation sur structures de test est proposĂ©e.In a very competitive and innovative context, it is crucial to be able to evaluate the performance of sensors with accuracy. To do so, two characterization supports are possible: the complete sensor or test structures. Parameters are extracted on full sensor in an environment and in conditions close to the application. Test structures, on the other hand, allow to focus on a specific region of a pixel, to study physical phenomena involved and to dissociate the different possible contributions to a studied pixel feature. A better understanding of this same parameter extracted on a complete sensor is then possible. Moreover, they make easier the study of different process tests in early development. The work of this manuscript proposes new methods to measure and characterize parameters on test structures complementary to what is done on a complete sensor. In this manuscript, new test structures are developed in order to study the contribution of the backside interface of BSI pixels to the dark current. A new method of potential extraction is also presented and allows the extraction of a multitude of potentials of interest present in the pixels. Finally, a new method of extraction of the Full Well Capacity on test structures is proposed