abstract |
A process for trimming a photoresist layer during the fabrication of a gate electrode in a MOSFET is described. A bilayer stack with a top photoresist layer on a thicker organic underlayer is patternwise exposed with 193 nm or 157 nm radiation to form a feature having a width w 1 in the top layer. A pattern transfer through the underlayer is performed with an anisotropic etch based on H 2 /N 2 and SO 2 chemistry. The feature formed in the bilayer stack is trimmed by 10 nm or more to a width w 2 by a HBr/O 2 /Cl 2 plasma etch. The pattern transfer through an underlying gate layer is performed with a third etch based on HBr/O 2 /Cl 2 chemistry. The underlayer is stripped by an O 2 ashing with no damage to the gate electrode. Excellent profile control of the gate electrode is achieved and a larger (w 1 −w 2 ) is possible than in prior art methods. |