p-MOS transistor: In this module students will design and fabricate a working p-MOS transistor. Students will design and fabricate masks and will carry out the multi-step processing necessary to produce the devices and will characterize the transfer characteristics with an emphasis on understanding deviations from ideal square-law behavior.
  1. Start with a lightly doped n-type silicon wafer and clean it.
  2. The chips are then etched to remove the native oxide
  3. A field oxide is then grown
  4. Perform photolithography I (to form the p-wells), which includes spinning on the photoresist, softbake, exposure, development, and a hardbake
  5. Oxide etch (where photoresist is absent)
  6. Remove the photoresist
  7. Spin on the borofilm and diffuse in an oven
  8. Etch the boroglass off
  9. Perform photolithography II (to etch the field oxide in the gate oxide area), which includes spinning on the photoresist, softbake, exposure, development, and hardbake
  10. Oxide etch (where the photoresist is absent)
  11. Remove the photoresist
  12. Grow the gate oxide
  13. Perform photolithography III (to metallize contacts over the p-wells), which includes spinning on the photoresist, softbake, exposure, development, and hardbake
  14. Etch the gate oxide above the p-wells (exposed area)
  15. Metallize contacts over the p-wells with aluminum
  16. Liftoff the metal on top of photoresist
  17. Perform photolithography IV (to metallize contacts over the gate oxide and again over the p-wells OR over the drain, gate, and source), which includes spinning on the photoresist, softbake, exposure, development, and hardbake
  18. Metallize contacts over the gate oxide, again over the p-wells and on the bottom of the chip with aluminum
  19. Liftoff the metal on top of photoresist

   

 

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