Arun's Tech Blog


My First Wafer!

Finished processing the first layer on my first microelectromechanical systems device wafer today! Took it through the entire process. Cleaning -> Chromium deposit -> Gold deposit -> L-edit design -> Masks made offsite -> Cleaning -> HMDS spin-on -> Photoresist spin-on -> Prebake -> Exposure -> Postbake -> Development -> Gold etch -> Chrome etch -> Resist strip. The devices on the images below are on at a micron scale. Lets take a look!

Wafer processing - microscope
Who would have guessed that one day I would use a microscope for something actually useful?

Wafer processing - development
Photoresist development looks spot on – disregard the dirty microscope lense

Wafer processing - low zoom
Alright! The thicker beams are definitely etched well but it looks as if the 4-micron beam may be overetched

Wafer processing - high zoom
Perfect(to nitpick there does appear to be a small section of chromium exposed)! But that beam is a little less than four microns wide!

There is something incredibly gratifying about manufacturing something at what could be a professional level of quality, especially at this size. Also, I managed to not be the guy who breaks the $200 dollar production wafer! After this, I definitely appreciate those Intel MOSFET gate lengths of 14 nanometers a lot more. This was done on a silicon on insulator wafer. The gold layer itself isn’t particularly interesting as the gold/chromium is used exclusively for contacts and reducing the resistivity in certain areas of the device. Next up is the device layer photolithography but with deep reactive ion etching instead of a wet-etch. And finally a wet release etch of the buried oxide to make the devices fully functional. Stay tuned!

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