Saturday, January 17, 2009

Weekly Patent Review

One funny quote on pixel operation from Samsung application US2009000868, paragraph [0005]:

"...if light is detected in the photodiodes, electron-hole pairs (EHP) are generated and accumulated. The accumulated electron-hole pairs are transferred to the floating diffusion region via the transfer transistor. As a result, the potential in the floating diffusion region is changed, and the active pixel sensor detects and outputs the change in potential."

The application mostly talks about process ideas. I have seen that process engineers sometimes do not understand the intimate details of pixel operation, so it's somewhat excusable. Still, it's quite rare to see such a glaring mistake in an official document from one of the leading image sensor companies.

Siliconfile application US20090008737 has a title "Image sensor having anti-reflection film and method of manufacturing the same". Contrary to the common meaning, the anti-reflection films (250) prevent the reflections from metal layers, as shown:

The anti-reflection films are said to include "at least one of polysilicon, amorphous silicon, tungsten, and TiN". On the negative side, if these films are conductive, they can significantly increase pixel parasitic capacitances.

1 comment:

  1. Sometimes in a big company the patent is written in a different department, based on the disclosure. So, the original disclosure, undoubtedly in Korea, may have been correct but somewhere along the chain incl. English translation, silly mistakes may have happened. It happens at big US companies too. The patent guys writing the application may not have a firm grasp on all the lingo or details, and the typos may not be caught by the inventor esp. if the application is sent at the last moment to the inventor for review. Patent attorneys always seem to wait until the last possible day to file things. It can drive one nuts.


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