INTEGRATED ELECTRONIC SHUTTER FOR BACK-ILLUMINATED CHARGE-COUPLED-DEVICES

A novel electronic shutter has been integrated into the structure of a back-illuminated frame-transfer charge-coupled device (CCD) to permit short optical exposure times and to reduce the smear that occurs duri ng the transfer of an image from the CCD detection area. The shutter c onsists of an n+ shutter drain placed in the vertical channel stop reg ions and stepped p-type buried layers formed by a high-energy implanta tion (1.0-1.5 MeV) located between CCD n-type buried channel and p- su bstrate. These structures create electric fields that direct the photo electrons to either the CCD detection region or the n+ shutter drain. The ratio of photons detected with the shutter open to photons detecte d with the shutter closed has been measured to be greater than 75 000 for wavelengths below 540 nm. The corresponding shutter rise and fall times are less than 55 ns.