An all pixel PDAF CMOS image sensor with 0.64μmx1.28μm photodiode separated by self-aligned in-pixel deep trench isolation for high AF performance

We present a CMOS image sensor (CIS) with phase detection auto-focus (PDAF) in all pixels. The size of photodiode (PD) is 0.64μm by 1.28μm, the smallest ever reported and two PDs compose a single pixel. Inter PD isolation was fabricated by deep trench isolation (DTI) process in order to obtain an accurate AF performance. The layout and depth of DTI was optimized in order to eliminate side effects and maximize the performance even at extremely low light condition up to 1lux. In particular the AF performance remains comparable to that of 0.70μm dual PD CIS. By using our unique technology, it seems plausible to scale further down the size of pixels in dual PD CIS without sacrificing AF performance.