Line end shortening and iso-dense etch bias improvement by ALD spacer shrink process

Abstract Multiple patterning employing etch shrink extends the scaling of hardmask open CD (HCD) to sub-50nm regime. A plasma-assisted shrink technique is primarily used in the back-end-of-line (BEOL) however it faces major challenges such as the line end shortening (LES) and large critical dimension iso-dense bias (IDB). In order to mitigate these two problems we apply an atomic layer deposition (ALD) spacer shrink process at 10nm metal interconnect layer with sub-20nm minimum half-pitch. As a result we observed 8nm LES improvement in tip-to-tip (T2T) two-dimensional (2D) structures, and 5nm IDB reduction in one-dimensional (1D) structures. These improvements suggest that the ALD spacer shrink can contribute to more precise CD control in multiple patterning.