A 1/3-in 1.3 M-pixel single-layer electrode CCD with a high-frame-rate skip mode

A 1/3-in 1.3 M-pixel interline-transfer charge-coupled-device (IT-CCD) image sensor has been developed for digital-camera applications. A 0.25-/spl mu/m-gap single-layer poly-Si is used for the CCD electrodes. The vertical CCD (V-CCD) of the image sensor has ten-phase metal wiring to enable various charge-transfer modes. A high-frame-rate skip mode (75 frames/s) and an advanced 3:1 interlaced-scan mode were developed and tested. A method of separately implanting boron ions for the V-CCD and horizontal CCD in single-layer electrode CCDs with small pixels, to maintain high charge-transfer efficiency, was developed. However, reducing pixel size degrades the light-gathering capability of the on-chip microlens, which occurs especially obliquely incident light, thus, reducing the sensitivity for a given camera-iris aperture (f-number). A new thin flattened-layer (3.5 /spl mu/m thickness) microlens improved the sensitivity of the device. At f-number 1.4, for example, there was an 18% increase in sensitivity compared to that of the thick flattened-layer (5.0 /spl mu/m thickness) microlens.