Active pixel sensor integrated with a pinned photodiode

A method of forming an active pixel sensor comprising the steps of:

• providing a semiconductor substrate of a first conductivity type with an array of pixels on it;
• and
• providing at least one pixel with a pinned photodiode having a pinning layer heavily doped of the first conductivity type and a photodiode heavily doped of a second conductivity type and at a depth deeper than source and drain regions of CMOS within the array of pixels that is operatively coupled to a sensing node conpised of a floating diffusion connected to a CMOS control circuitry through a transfer gate controlled by said CMOS control circuitry, the at least one pixel further comprising means for transferring charge from the pinned photodiode to a floating diffusion area under control of a transfer gate for charge to voltage conversion within the pixel such that the pinned photodiode, the transfer gate and a charge sensing means acts as, respectively, the source, the gate and the drain of a MOSFET.