This report is an Imager Process Review of the Sony IMX278 13 MP stacked back illuminated (BI) CMOS image sensor (CIS) extracted from a Huawei P8 smartphone. The IMX278 is Sony's third generation of the 13 MP Exmor RS series stacked BI CIS, featuring, for the first time a RGBW color filter array and back deep trench pixel-to-pixel isolation. Also for the first time, Sony used an AlO antireflection (AR) layer instead of HfO. The TSVs formation process for the IMX278 has completely changed by using deep trench isolation (DTI) to isolate the TSVs from the CIS silicon substrate, and a single deep TSV to connect both the CIS and ISP dies.