CMOS pixel-aperture and offset pixel-aperture techniques for 3-dimensional imaging

Pixel-aperture and offset pixel-aperture techniques for 3-dimensional complementary metal oxide semiconductor (CMOS) image sensors are presented in this talk. In conventional camera systems, the aperture is located between the object and the CMOS image sensor (CIS). This type of image sensor consists of a pixel array with red, green, and blue (RGB) Bayer pattern color filters. Our proposed image sensor uses red, green, blue, and white (RGBW) filters, and the aperture is located on the W pixel which is without any color filter. A sharp image can be obtained from the W pixels, and the RGB pixels produce a defocused image with blurring. The sharp image can be compared with the defocused image to obtain depth information for 3D imaging. A metal layer, such as aluminum in the conventional CIS process, is used for the aperture on the white pixel. Offset pixel-aperture structures for disparity information are also considered. We designed and simulated pixel models for the pixel-aperture and offset pixel-aperture structures using a 0.11 µm CIS process and evaluated the performance of the proposed structures using finite-difference time-domain (FDTD) analysis. The proposed structures have been fabricated and some experimental results will also be presented.