Nikkei publishes an article on Olympus IEDM 2015 presentation on stacked visible and IR sensor. While it mostly re-iterated the previously published data, some info is new:
"The laminated image sensor is made by combining (1) an image sensor equipped with an RGB color filter for visible light (top layer) and (2) a near-infrared image sensor (bottom layer). Each layer functions as an independent sensor and independently outputs video signals.
The visible-light image sensor is a backside-illuminated type, and its light-receiving layer (made of semiconductor) is as thin as 3μm. Each pixel measures 3.8 x 3.8μm, and the number of pixels is 4,224 x 240."