A 1/1.57-inch 50Mpixel CMOS Image Sensor With 1.0μm All-Directional Dual Pixel by 0.5μm-Pitch Full-Depth Deep-Trench Isolation Technology

As the strong demand for higher resolution and new functionality is rapidly increasing in the mobile CMOS Image Sensor (CIS) market, we have seen the emergence of: submicron pixels, >200M pixels, fast readout, global shutter, high dynamic range, and phase-detection autofocus (PDAF) [1 – 3]. Among these, PDAF is an essential feature of cutting-edge CIS for accurate autofocus at extremely low-light situations, and dual-pixel technology has been widely used for AF of the entire image area [4]. To implement high pixel resolution in a limited optical size, the pixel size has continued to shrink, and the pixel structure has evolved to maintain high image quality. However, for a dual pixel, integrating two photodiodes (PDs) in one pixel by backside deep trench isolation (BDTI) has technical limitations and causes degradation of image AF performance as well as image quality.