Fujitsu Corporation

Tetsuo Nishikawa

Akira Takei

Eiichi Nagai

Teruyuki Nabeta

A charge coupled device (CCD) has a charge storage region and a potential barrier region. The CCD includes a first layer made of a first conductivity type semiconductor, a second layer made of a second conductivity type semiconductor and provided on the first layer, where the first and second conductivity types are mutually opposite types selected from n-type and p-type semiconductors, a third layer made of a first conductivity type semiconductor, impurity diffusion regions provided in at least a surface part of the third layer and having an impurity density higher than that of the third layer, a first gate electrode provided on the third layer between two mutually adjacent impurity diffusion regions, and a second gate electrode provided on each impurity diffusion region of the third layer. The impurity diffusion region forms the charge storage region of the CCD and the third layer between the two mutually adjacent impurity diffusion regions forms the potential barrier region of the CCD.

Charge coupled device and method of producing the same

Field isolation between arrayed picture cells of an image sensor is fabricated thinner than the insulation layer for the peripheral portion of CCD operatively connected to picture cells. The field isolation is fabricated by a selective thermal oxidization, by which the isolation film inflates not only vertically but also laterally, therefore the thinner isolation layer can be narrower. And, the lower applied voltage to the picture cell than applied voltage to the CCD portion allows the narrower isolation. The narrower field isolation between the picture cells allows greater density of integration of the picture cells. Procedures to embody the invention are disclosed, one of which is to fabricate the thinner isolation first, and another one is the thicker insulation layer first.

Image sensor

An image sensor includes a plurality of potential monitoring transistors connected to respective floating electrodes for separately monitoring changes in potential of the respective floating electrodes. In addition, the image sensor includes an output circuit for producing an output signal which varies in accordance with one of the monitored potentials which is one of the highest potential and the lowest potential.

Growing community of inventors

Kawasaki, Japan

Tetsuo Nishikawa