Patent Number: 6,528,833

Title: CMOS active pixel for improving sensitivity

Abstract: A CMOS active pixel of increased sensitivity includes a floating diffusion layer, a photo-diode, a reset circuit and an output circuit The floating diffusion layer is of a first dopant type and receives a signal charge. The photo-diode generates the signal charge depending on an energy inputted thereto and transfers the signal charge to the floating diffusion layer. The photo-diode has first and second lower diode dopant layers of the first dopant type and an upper diode dopant layer of a second dopant type. The polarity of the second dopant type is opposite to that of the first dopant type. The first and second lower diode dopant layers are formed to contact a lower portion of the upper diode dopant layer. The upper diode dopant layer and the first lower diode dopant layer are formed to contact the floating diffusion layer. The second lower diode dopant layer is formed to contact the first lower diode dopant layer. The reset circuit controls a voltage level of the floating diffusion layer to a reset voltage level in response to a control signal. A doping concentration of the first lower diode dopant layer is less than that of the floating diffusion layer. A doping concentration of the second lower diode dopant layer is less than that of the first lower diode dopant layer.

Inventors: Lee; Seo Kyu (Cheongju, KR), Min; Dae Sung (Daejeon Metropolitan, KR)

Assignee: Pixelplus Co., Ltd.

International Classification: H01L 27/146 (20060101); H01L 031/062 ()

Expiration Date: 03/04/2020