Question

You want to create narrow polySi gates for Si MOSFET transistors.

You are given the photomask to be used for polySi gate definition, and it is mostly opaque (i.e., you cannot see much light through it). Do you choose positive or negative photoresist to apply to the wafers?

After completing the lithography steps and RIE etching of the polySi gate in the problem above, you find that the gate is too wide. You cannot make another mask. Describe two process changes in gate fabrication you can use to narrow the gate using the same mask.

Answer 1