Friday, March 09, 2018

TechInsights Publishes Samsung 0.9um Tetracell Pixel Analysis

Techinsights publishes reverse engineering report of Samsung 0.9um Tetracell pixel sensor:

There are many reasons we are excited about the Samsung S5K2X7SP 0.9µm Image Sensor, including Samsung’s claims about it:
  • “Slim 2X7 with Tetracell technology” (.9um, 24MP)
  • The first 0.9 µm generation pixels in mass production
  • Targeting both front and rear cameras
As well as its noted technology features:

Improved ISOCELL technology with deeper deep trench isolation
  • (DTI)Reduced color crosstalk
  • Expands the full-well capacity to hold more light information
  • At 0.9um, allows 24Mp image sensor to fit in a thinner camera module
Tetracell Technology
  • Merges four neighboring pixels to work as one for better light sensitivity in low light situations


  1. "front and rear cameras" - sounds like an automotive product.

    in the cross section image the barriers between the cells are clearly visible when viewed at full scale. surprisingly the lower ends have higher contrast and look quite white there. the color filters on the bottom end can be distinguished by their thickness and their variation of gray.

    as a side note, the device is most probably following a BSI design with the fine grained structures on the upper end and the photo sensitive cells on the bottom end with a set of micro lenses on the very bottom. - seems the cross section photographer and annotator were reluctant to turn the image by 180° to make the surface for the incoming light appear on the top as many people would try to do... ;-)

    1. "front and rear cameras" - sounds like an automotive product.
      ...or mobile phone product. (correcting myself)

  2. why do the micro-lens appear misaligned with the pixels?

    1. Albert Theuwissen - Harvest ImagingMarch 12, 2018 at 2:55 PM

      To limit the light fall-off towards the edges of the sensor (what I call sensor "vignetting"). Without the misalignent, the micro-lenses would focus the light next to the photodiode, at least for the pixels at the edge of the sensor surface.

    2. Thank you for the answer!

    3. guessing:
      the micro lens grid on the center of the imager is perfectly aligned whilst going to the outside of the sensor plane the micro lenses tend towards the center.

      imagine the rays of light coming from the classic lens system is (for the center rays) a pyramid or cone shape. thus any additional lens with a significant offset to some other structure needs to take into account the slope of the ray to make the optimum match.

    4. This comment has been removed by the author.

  3. the "aperture grid metal" sees a little shift as well.
    probably incoming rays for this cross section area are meant to originate from a source on the very bottom right (outside the area of the cross section picture). at least that's my thesis for reasoning what can be observed.


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