Hamamatsu enhances IR sensitivity by MEMS structures
These sensors are said to utilize MEMS structures fabricated by using "unique laser processing technology" to achieve a significant enhancement of NIR sensitivity. Another explanation of MEMS action is on Electro Optics site: "Using unique laser processing technology, MEMS structures can be fabricated on the silicon surface, which act to reduce reflections and increase the surface area of the active element. This process drastically increases the sensitivity in wavelengths longer than 800nm."
PIN diode NIR extension is quite big, as seen on Figure 1 (Hamamatsu NIR BSI CCD).
In case of BSI FT-CCD the MEMS structure is formed at the backside and NIR extension is somewhat less than in the PIN diode case, see Figure 2 (Hamamatsu NIR CCD)..
MDT: The S11510 BSI CCD features QE "of 40% at 1,000 nm, without the need for a deep depletion structure, with its corresponding drawback of higher dark signal. The S11510 series is available with 1,024 or 2,048 pixels, with each pixel measuring 14 by 14 µm." The new NIR CCD products have been announced about a year ago, but the PR had no reference to the MEMS technology at that time (figure 3: Hamamatsu NIR BSI CCD).