Investigation of the influence of resist patterning on absorber LWR for 22-nm-node EUV lithography

Achieving the specifications of resolution, sensitivity and line width roughness (LWR) of wafer resist is one of the top challenges of bringing extreme ultraviolet lithography (EUVL) into high volume manufacturing. Contributions to the resist LWR on wafer can be divided into two categories; chemical properties of the resist and aerial image. Chemical properties of the resist are complicated and many factors contribute to LWR, such as polymer size, sensitivity, surface reaction etc. Aerial image LWR is much simply determined by the optical properties of a mask and a scanner. Since very small LWR value of the resist is needed, EUV mask LWR is also set very severely from ITRS [1] . In our previous work [2] , we demonstrated current mask LWR as comparing them with mask resist LWR and absorber LWR. As a result, we found that the absorber's LWR almost depends on resist patterning. In this paper, we will present the influence of resist patterning on absorber LWR comparing resist materials and EB tools. From the results, LWR has been reduced by 10-20% by improving EB tool. However, the LWR value at line and space pattern for 22nm-hp case have not met target of ITRS' roadmap while, by using Non-CAR, the LWR value has met the target. In particularly, the value at isolated line is dramatically improved using Non-CAR.