Sony Proposes Moisture Collecting Holes Between Microlens

Sony patent application US20170278889 "Solid-state imaging device, method of manufacturing the same, and electronic apparatus" by Takashi Nakashikiryo, Yoshiaki Kitano, Yuuji Nishimura, Kouichi Itabasi, Ryou Chiba, Yosuke Takita, Mitsuru Ishikawa, Toyomi Jinwaki, Yuichi Seki, Masaya Shimoji, Yoichi Ootsuka, and Takafumi Nishi says that sensors with AR coating on top of micoelens have a problem:

"In a case where an antireflection film is provided on the surfaces of the microlenses, however, if BSIs are left in a high-temperature, high-humidity condition for a long period of time, the moisture generated in part of the regions of the interfaces between the microlenses and the antireflection film might not permeate through the antireflection film but remain therein, resulting in generation of water droplets. In this case, the captured image is stained by the water droplets, and the quality of the image is degraded."

So, Sony proposes the moisture collecting holes in the corners between the microlenses: