Many have been wondering what Junichi Nakamura's startup Brillnics is working on, especially after TSMC pixel group head S.G. Wuu has joined them. Two PCT patent applications might shed some light on it:
WO2016009942: SOLID STATE IMAGING DEVICE, METHOD FOR PRODUCING SOLID STATE IMAGING DEVICE, AND ELECTRONIC APPARATUS by TAKAYANAGI, Isao; TANAKA, Shunsuke; MORI, Kazuya; ARIYOSHI, Katsuhiko; MATSUO, Shinichiro.
WO2016009943: SOLID-STATE IMAGING DEVICE, METHOD FOR PRODUCING SOLID-STATE IMAGING DEVICE, AND ELECTRONIC APPARATUS by AKAYANAGI, Isao; TANAKA, Shunsuke; MORI, Kazuya; ARIYOSHI, Katsuhiko; MATSUO, Shinichiro.
While the detailed description is in Japanese, just from the abstract and figures, it appears to be a stacked sensor built on CMOS pixel with CCD-like charge transfer and storage:
"This solid-state imaging device 100 has: a light sensitive unit that includes pixel units 211, which are disposed in a matrix, and charge forwarding units 212 for forwarding, by the column, the signal charge of the pixel units; a plurality of charge accumulation units 220 that accumulate the signal charges forwarded by the plurality of charge forwarding units of the light sensitive unit; a relay unit 240 that relays the forwarding of the signal charges forwarded by the plurality of charge accumulation units to each charge accumulation unit; an output unit 230 that outputs the signal charges of the plurality of charge accumulation units as electric signals; a first substrate 110 at which the light sensitive unit 210 is formed; and a second substrate 120 at which the charge accumulation unit 220 and output unit 230 are formed. The first substrate and second substrate are laminated together, and the relay unit 240 electrically couples the charge forwarding unit of the first substrate to the charge accumulation unit of the second substrate by means of a connection section traversing the substrates outside the light sensitive region of the light sensitive unit."
The most interesting part is a charge transfer between the stacked dies through TSV: