Chipworks Reveals Sony BSI Secrets

Semiconducor International publishes Chipworks' Ray Fontain's article on Sony BSI sensor reverse engineering findings. The article reveals:

• Sony BSI uses SOI process - meaning it's not cheap.
• The sensor's backside has AR layer
• The backside uses aperture grid made of tungsten
• Assuming the pixel size of 1.75um, the silicon layer thickness is about 2.8um
• It appears there is 0.8-0.9um thick spacer between microlens and color filter, so the distanse from microlens to the silicon surface is about 2um
  
  The picture below shows the sensor cross-section:
  
  

Update: It appears that Sony uses an additional conforming AR layer on top of microlens (should I say on bottom of microlens?).