可应用于CMOS彩色图像传感器的两层垂直层叠结构及其色彩特性的研究

Vertically Integrated Diode for CMOS Color Image Sensor and Its Colorimetric Characterization

基于两层垂直层叠结构的色彩传感器可同时对偏蓝波段和偏红波段进行感应, 配合绿/品红滤波片, 为彩色成像提供了可能, 由于它完全兼容于标准CMOS工艺, 可以作为一种新型的CMOS彩色图像传感器像素的感光功能器件。通过垂直层叠结构, 配合两色滤波片, 抽取不同深度的光生载流子, 即可以得到相应波段的成像信息。通过仿真和实验得到了它的各通道响应曲线, 提出了一种增强对了声稳健性的多个多项式回归的方法并得到色彩转换矩阵, 把传感器的4通道响应转换为CIE XYZ三刺激值。同时在CIE L＊A＊B＊空间中对器件传感得到的色彩和原始的色彩坐标进行了比对, 对器件的色彩准确度进行了一个量化评估。结果表明在应用新转换方法, 色彩误差大大优于常用的简单线性转换, 其色彩效果甚至优于商用Bayer滤光片式彩色CCD。

The vertically integrated diode can sense blue and red illumination simultaneously, and can provide full color information with green/magenta filter on it. It can also be used in the CMOS image senor for its fully compatibility with standard CMOS process. Through extraction of photogenerated carriers at different depths by vertically integrated diode with two color filters, the full color image is got. Through simulation and experiment, each channals response curve is got, an enhanced sound-robust method with multi-polynomial regression is proposed, and the color space transform matrix is obtained. The sensors four-channel response is converted to CIE XYZ three-stimulus-values. In the CIE L＊A＊B＊ space, comporation between cooridinate and sensed color coordinate is proposed, and the apparatus color accuracy is quantitively evaluated. The result shows that the device colorimetric accuracy is superior to that of a simple linear transformation, even better than commercial colorful CCD with Bayer filter.