Correlation of Experimental and Simulated Cure-Induced Photoresist Distortions in Double Patterning Thomas I. Wallow* a , Mahidhar Rayasam a , Masanori Yamaguchi b , Yohei Yamada b , Karen Petrillo c , Kenji Yoshimoto d , Jongwook Kye a , Ryoung-han Kim e , and Harry J. Levinson a a GlobalFoundries, 1050 East Arques Avenue, Sunnyvale, CA 94085; b Ushio Incorporated, 1194 Sazuchi, Bessho-cho, Himeji, Hyogo Prefecture JAPAN 6710224; c IBM Corporation, 255 Fuller Road, Albany, NY, 12203; d GlobalFoundries, 2070 Route 52, Hopewell Junction, NY, 12533; e GlobalFoundries, 255 Fuller Road, Albany, NY, 12203 ABSTRACT Numerous alternate processes are under industry-wide evaluation as simplifications to current double patterning methods. Reduction in process complexity and cost may be achieved by use of photoresist stabilization methods that eliminate one etch step by allowing a second resist to be patterned over the first resist pattern. Examples of stabilization methods using numerous curing processes have been reported. At least some resist shrinkage during stabilization appears to be generally observed for these methods. We evaluate the link between volumetric shrinkage and three- dimensional pattern distortion for a variety of resist geometries using experimental and simulation-based methods. Experimental resists designed for double patterning using 172 nm UV resist curing were evaluated and showed shrinkage of less than 10 percent. Several simplified metrology approaches for measuring shrinkage as well as inferring shrinkage distortions were assessed. For top-down SEM measurements, elbow inner corner rounding measurements appear to be a usefully robust method for estimating shrinkage distortion. Finite element analysis of resist structures yields shrinkage distortions that are in good qualitative and quantitative agreement with experiments, and thus appears to provide a provisionally general and useful method for predicting pattern distortions that arise during cure-based resist stabilization methods used in double imaging. Keywords: photoresist, distortion, shrinkage, curing, double patterning, simulation, metrology, 172 nm 1. INTRODUCTION Double patterning methods that simplify integration of lithographic and etch processes are of growing importance due to their potential for improved manufacturing throughput and cost savings. Increasing efforts in this area center on double imaging processes in which two or more independent lithographic patterns are generated in sequentially applied resist films, then transferred in a single etch step. 1-14 In previous reports, 15,16 we demonstrated that 172 nm cure stabilization, when properly implemented, can result in superior retention of photoresist profiles compared to broadband UV curing (Fig. 1). We documented that the approximately 25 percent volumetric shrinkage observed for a non-optimized resist during stabilization resulted in controlled CD trimming and thickness loss as well as three-dimensional resist pattern distortions that included a) line- end tilting and pullback and b) elbow corner tilting and displacement. We concluded that shrinkage control during any stabilizing process is a critical factor for both a) determining the suitability of a given double imaging method for patterning complex resist structures and b) designing photoresists for cure-based double imaging methods. *tom.wallow@globalfoundries.com ; 408-749-2513 Advances in Resist Materials and Processing Technology XXVI, edited by Clifford L. Henderson, Proc. of SPIE Vol. 7273, 727309 · © 2009 SPIE · CCC code: 0277-786X/09/$18 · doi: 10.1117/12.814474 Proc. of SPIE Vol. 7273 727309-1