Impact of patterning strategy on mask fabrication beyond 32nm

Mask specifications of the pitch splitting type double patterning for 22nm node and beyond in logic devices have been discussed. The influences of the mask CD error and the mask induced overlay error on wafer CD have been investigated in both cases of bright field and dark filed. The specification for intra-layer overlay alignment is much smaller than inter-layer one. The specification of mask CD uniformity for dark is more challenging. In order to overcome the technology gap between single patterning and double patterning, many things will have to be improved.