The GATE Grind

GATE 2014 EC (EC3) – Question 18

Electronic Devices · P-N Junction and Semiconductor Devices · 1 mark · Multiple choice

During which MOSFET fabrication process is channel length defined?

  1. Isolation oxide growth
  2. Channel-stop implantation
  3. Polysilicon gate patterning
  4. Lithography for contact pads

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Show answer and explanation

Correct answer: (C) Polysilicon gate patterning

Explanation

In a self-aligned MOS process, the patterned polysilicon gate establishes the lateral channel extent between source and drain. Hence the channel length is defined during **poly-silicon gate patterning,C**. Isolation, channel-stop implantation and contact-pad patterning serve different fabrication purposes.