Sony 13MP HDR Stacked Sensor Analysis

Chipworks publishes a series of reverse engineering reports on Sony IMX214 stacked sensor based on 1.12um pixel. The device is defined as "a second generation13 MP Exmor RS “stacked” CIS with spatially multiplexed exposure-high dynamic range (SME-HDR). SME-HDR technology involves imaging at two different exposure conditions and performing image processing to generate images with wide dynamic range."

The logic die photo reveals a lot of empty space in the middle of the die: