OPC-free on-grid fine random hole pattern formation utilizing double resist patterning with double RETs

Advances in Resist Materials and Processing Technology XXVI

Rayasam

Yamaguchi

et al. 2009

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 threedimensional 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.

Section: Introductionmentioning

confidence: 68%

Correlation of experimental and simulated cure-induced photoresist distortions in double patterning

Advances in Resist Materials and Processing Technology XXVI

Rayasam

Yamaguchi

et al. 2009

“…Design rule modification to accommodate double imaging has been previously proposed and discussed. 5,22 Second, process-based refinement and resist materials advances can be expected to yield pattern stabilization processes with higher cure sensitivity, lower shrinkage, and correspondingly lower distortion. Experimental results presented here are based on the behavior of a single commercial photoresist that was not designed with pattern freezing in mind.…”

Section: Impacts On Double Imaging Utilitymentioning

confidence: 99%

“…1͒. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Stabilization of the first photoresist pattern before processing of the second resist pattern is necessary in double imaging. Without stabilization, the first resist pattern will swell or dissolve on application of the second resist film, or undergo additional exposure and development during the patterning of the second resist.…”

Section: Introductionmentioning

confidence: 99%

Cure-induced photoresist distortions in double patterning

J. Micro/Nanolith. MEMS MOEMS

Rayasam

Yamaguchi

et al. 2009

Many processes are under evaluation as simplifications to current double patterning methods. Reduction in process complexity and cost may be achieved by use of track-based photoresist stabilization methods that eliminate one etch step by allowing a second resist to be patterned over a first resist. 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 shrinkage and three-dimensional pattern distortions at line ends and elbow corners using experimental and simulation-based methods. A 172-nm UV resist curing process was used to produce controlled shrinkage ranging from 5% to 30%: shrinkage was correlated with resist distortions. At cure dose sufficient to stabilize the resist, shrinkage of approximately 23% results in measured line-end pullback and elbow displacement of approximately 16% and 13% of nominal linewidth respectively, when measured at resist half-height. Finite element analysis of resist beam structures produces shrinkage distortions that are in good qualitative and semiquantitative agreement with these measurements 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.

“…Litholitho-etch (LLE) processes, in which a first photoresist image is cured and over-coated with a second photoresist layer, which, in turn, is imaged to form a joint final etch mask, are of continuing interest. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] This scheme offers great conceptual simplicity and promises cost savings vs. litho-etch-litho-etch approaches. However, the chemistry of high resolution imaging followed by curing presents significant challenges.…”

Section: Introductionmentioning

confidence: 98%

Photoresist stabilization for double patterning using 172 nm photoresist curing

Advances in Resist Materials and Processing Technology XXVI

Dai²,

Szmanda³

et al. 2009

We describe progress in low-k 1 factor double patterning using 172 nm ultraviolet (UV) curing as a resist stabilization method. Factors that have contributed to enhanced patterning capability include a) resists design and optimization for both patterning and UV curing; b) use of unique R&D tooling capabilities to rapidly identify and optimize key process variables; c) development of simple process metrics for characterizing double patterning process quality, and d) use of 172 nm-resistant antireflective materials. A designed resist, XP-7600A, was selected for detailed evaluation based on superior patterning and curing behavior (less than 10 percent volumetric shrinkage during cure.) Process optimization on 172 nm damage-prone antireflective coatings produced 60 nm cross-grid contact holes at 0.93 NA (litho k 1 = 0.28) with good uniformity when an ancillary 150 o C post-UV bake was used. Additional optimization on improved antireflective coatings yielded superior process latitude (>20 percent 172 nm dose latitude) and also demonstrated that a UV-cure-only resist stabilization process flow may be attainable. Under optimized conditions, highly uniform 60 nm half-pitch cross-grid contacts with cross-sectional area uniformity (1σ) of approximately 200 nm 2 (5 percent) are produced at 135 nm resist film thickness.