Enhanced spacer-is-dielectric (sid) decomposition flow with model-based verification

Abstract

Self-aligned double patterning (SADP) lithography is a leading candidate for 14nm node lower-metal layer fabrication. Besides the intrinsic overlay-tolerance capability, the accurate spacer width and uniformity control enables such technology to fabricate very narrow and dense patterns. Spacer-is-dielectric (SID) is the most popular flavor of SADP with higher flexibility in design. In the SID process, due to uniform spacer deposition, the spacer shape gets rounded at convex mandrel corners, and disregarding the corner rounding issue during SID decomposition may result in severe residue artifacts on device patterns. Previously, SADP decomposition was merely verified by Boolean operations on the decomposed layers, where the residue artifacts are not even identifiable. This paper proposes a model-based verification method for SID decomposition to identify the artifacts caused by spacer corner rounding. Then targeting residue artifact removal, an enhanced SID decomposition flow is introduced. Simulation results show that residue artifacts are removed effectively through the enhanced SID decomposition strategy.

Spacer-is-dielectric-compliant detailed routing for self-aligned double patterning lithography

“…11(b). The remaining 'spur' shaped residue can be simply removed by post-processing such as mandrel extension and mandrel merging [7].…”

“…With high spacer width uniformity, the shape of the spacer gets rounded at convex mandrel corners even with perfect OPC for the mandrel mask [7], as shown in Fig. 3(a).…”

Detailed routing for spacer-is-metal type self-aligned double/quadruple patterning lithography

“…Meanwhile, we define Sc and Wc as the minimum spacing and minimum width values for cut mask. 2 Non-preferred jog [8] states that spacer deposited at a convex mandrel corner gets rounded even with refined OPC for the mandrel mask. Instead, the shape of spacers stays sharp at concave mandrel corners.…”