Reflectivity control through angle is challenging at hyper NA, especially for Logic devices which have various pitches in the same layer. When patterning critical layers, a multilayer antireflectant system is required in order to control complex reflectivity resulting from various incident angles. Multilayer antireflectants typically consist of an organic and inorganic (TiN and SiON) layers. Fewer or thinner layers are desired for etch pattern transfer. However, it would make the reflectivity control through angle more difficult. We have investigated several antireflectants for a simplified multilayer stack. The organic films differ in terms of n, k, thickness and etch rate. The n, k, and thickness span the ranges of 1.60-1.85, 0.15-0.30, and 30-130nm, respectively. The overall patterning performance including profiles, line width roughness (LWR), overlap depth of focus margin (ODOF) and critical dimension uniformity (CDU) has been evaluated. An immersion tool at 1.35NA was used to perform lithography. Simulation was performed using Prolith TM software.

As line width roughness (LWR) and depth of focus (DoF) become the critical lithography challenges, there is a growing interest in applying surface conditioner solutions during post-develops process to increase DoF and reduce LWR. Previous work 1 has demonstrated that a significant LWR reduction and DoF increase can be achieved through the utilization of a surface conditioner in the features of lines/spaces patterned for 45nm node by immersion lithography. However, the previous generation surface conditioner is not able to provide effective LWR improvement for the resist pattern having LWR less than 5nm.In this paper, 45nm lines/spaces features, having 4.8nm LWR, were patterned using immersion lithography to evaluate a newly-formulated surface conditioner's performance on LWR reduction. The results showed there is about 20% LWR reduction and the LWR was reduced to 4nm, which indicates the newly-formulated surface conditioner is capable of doing further LWR reduction on the pattern whose LWR is less than 5nm.In addition, surface conditioners were applied to extend the capability of 193nm "dry" lithography process window below the k2 = 0.3 threshold by DoF increase. The result demonstrated there is a significant process improvement on DoF which results in a usable DoF process window in practice comparable to that of "wet" lithography process.