Challenges and solutions of 28nm poly etching

Gate formation for 28nm node is LELE (2 times Litho, 2 times etch process) approach, which is different from traditional poly LE (Litho-Etch) process. Poly line and poly LEC (line end cut) formed during the second Litho etch process. It is great challenge to get appropriate LEC CD (Critical Dimension), meanwhile balance LEC position to achieve residue & pitting defect free. This paper introduces challenges and solutions of 28nm poly LEC etching, especially studies on LEC CD & defect control.