title: Toward one Giga frames per second--evolution of in situ storage image sensors.
abstract: The ISIS is an ultra-fast image sensor with in-pixel storage. The evolution of the ISIS in the past and in the near future is reviewed and forecasted. To cover the storage area with a light shield, the conventional frontside illuminated ISIS has a limited fill factor. To achieve higher sensitivity, a BSI ISIS was developed. To avoid direct intrusion of light and migration of signal electrons to the storage area on the frontside, a cross-sectional sensor structure with thick pnpn layers was developed, and named "Tetratified structure". By folding and looping in-pixel storage CCDs, an image signal accumulation sensor, ISAS, is proposed. The ISAS has a new function, the in-pixel signal accumulation, in addition to the ultra-high-speed imaging. To achieve much higher frame rate, a multi-collection-gate (MCG) BSI image sensor architecture is proposed. The photoreceptive area forms a honeycomb-like shape. Performance of a hexagonal CCD-type MCG BSI sensor is examined by simulations. The highest frame rate is theoretically more than 1Gfps. For the near future, a stacked hybrid CCD/CMOS MCG image sensor seems most promising. The associated problems are discussed. A fine TSV process is the key technology to realize the structure.
authors.affiliation: Research Organization of Science and Technology, Ritsumeikan University, Noji-Higashi 1-1-1, Kusatsu, Japan. etoh@fc.ritsumei.ac.jp
authors.forename: Takeharu G
authors.initials: TG
authors.lastname: Etoh
authors.forename: Dao V T
authors.initials: DV
authors.lastname: Son
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Yamada
authors.forename: Edoardo
authors.initials: E
authors.lastname: Charbon