Gridded design rule scaling: taking the CPU toward the 16nm node

The Intel 45nm PenrynTM CPU was a landmark design, not only for its implementation of high-K metal gate materials1, but also for the adoption of a nearly gridded design rule (GDR) layout architecture for the poly silicon gate layer2. One key advantage of using gridded design rules is reduction of design rules and ease of 1- dimensional scaling compared to complex random 2-dimensinal layouts. In this paper, we demonstrate the scaling capability of GDR to 16nm and 22nm logic nodes. Copying the design of published images for the Intel 45nm PenrynTM poly-silicon layer2, we created a mask set designed to duplicate those patterns targeting a final pitch of 64nm and 52nm using Sidewall Spacer Double Patterning for the extreme pitch shrinking and performed exploratory work at final pitch of 44nm. Mask sets were made in both tones to enable demonstration of both damascene (dark field) patterning and poly-silicon gate layer (clear field) GDR layouts, although the results discussed focus primarily on poly-silicon gate layer scaling. The paper discusses the line-and-cut double patterning technique for generating GDR structures, the use of sidewall spacer double patterning for scaling parallel lines and the lithographic process window (CD and alignment) for applying cut masks. Through the demonstration, we highlight process margin issues and suggest corrective actions to be implemented in future demonstrations and more advanced studies. Overall, the process window is quite large and the technique has strong manufacturing possibilities.