A 1/2-in, 1.3 M-pixel progressive-scan CCD image sensor employing 0.25-μm gap single-layer poly-Si electrodes

A 1/2-in, 1.3 M-pixel progressive-scan interline-transfer charge coupled-device (IT-CCD) image sensor has been developed for low-power and high-sensitivity digital cameras. The image sensor uses 0.25-μm gap single-layer poly-Si for CCD transfer electrodes in order to reduce the power consumption and number of fabrication process steps. The image sensor achieved a low driving voltage (2.1 V) on a horizontal CCD (H-CCD) at a frequency of 24.5 MHz. An original pixel layout and a self-aligned photodiode structure make it possible to achieve a progressive scan pixel with well-controlled photodiode readout characteristics. An output three-stage source follower amplifier with new multioxide transistors, whose gate insulator thickness is thinner than that of a CCD register, is able to attain 17% higher gain than that of the conventional amplifier. The sensor provides low-power (100 mW) and high output sensitivity. The total number of steps for fabricating the sensor was reduced to 70% of that for conventional three-layer poly-Si electrodes