Challenge for effective OCV control in 90-nm logic gate using ArF lithography

The introduction of ArF lithography technology is needed for on-chip linewidth variation(OCV) control less than 10nm in 90nm logic transistor development. Since conventional KrF lithography increased the burdens of mask fabrication and photo process due to excessive optical proximity correction(OPC), ArF lithography is more required to improve pattern feasibility in terms of line edge roughness(LER), corner rounding and contact overlapping margin than before. In this paper, we investigated two major components of OCV, that is, proximity and uniformity using ArF lithography. For a tighter CD control, the proximity can be corrected by hybrid OPC method, which is a combination of rule-based and model-based OPC. The uniformity can be effectively improved by several methods such as lithography-friendly layout formation, optimal substrate condition, decrease in MEEF and tuning of the resist process. In conclusion, by using ArF lithography we could obtain the satisfactory OCV control less than 10nm and reasonable process latitude simultaneously for 90nm logic gate under the condition of well-controlled proximity and uniformity.