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In addition to simulating lithography process effects, process models must accommodate pattern distortion due to the etching process. An etching bias modeling method and a staged correction strategy have been developed to compensate for such patterning process effects efficiently. However, the staged correction strategy may cause inaccurate compensation of patterning process effects since the patterns used to simulate etching process effects are assumed to be rectilinear. In fact, the patterns will be distorted during the lithography process. Therefore, a promising correction strategy that incorporates a recently developed optical proximity correction algorithm is proposed to deal with this problem. It can compensate for lithography and etching process effects simultaneously. In order to conduct this study, the etching bias modeling method is investigated by rigorous process simulations. The resulting model provides a reasonable fit to the measured data from the process simulations and can simulate etching process effects reasonably well. The performance of the proposed correction strategy in terms of correction accuracy and run time is examined. Numerical experiments show that the correction accuracy obtained is significantly improved compared with that obtained by the staged correction strategy. However, the total run time required is increased by a factor of ~2.5, which is practically acceptable for full-chip correction.

With the shrinkage of feature sizes, there is a need for bulk-resist models to evaluate resist performance in process simulators. This study investigates the sources of blur during image formation in chemically amplified resist (CAR) for extreme ultraviolet (EUV) exposure. It evaluates the acid generation blur due to photo acid generator (PAG) activation before post exposure bake (PEB) and the de-protection blur during PEB due to diffusion-reaction coupling of generated acids in the resist. The acid generation bulk-resist model is derived from the molecular formulation of resists [T. Kozawa, A. Saeki, S. Tagawa, Appl. Phys. Exp. 1 (2008) 027001]. While, the PEB de-protection blur is obtained from a chemical kinetics model [F.A. Houle, et. al. J. Vac. Sci. Technol. B19 (2000) 1874]. These derived bulk-resist models depend largely on the experimental data for obtaining resist-blur (kernel) parameters. In order to present the complete image formation in resist, an optimization model is proposed to build the kernel functionality and extract the kernel parameters using EUV critical dimension (CD) data on the test pattern.

Extreme ultraviolet lithography (EUVL) is a leading candidate for the 22nm node lithography and beyond. However, there are still some critical problems before EUVL may be deployed in high-volume manufacturing. One of the critical problems is to estimate the EUVL aerial image formation for optical proximity correction (OPC) in order to compensate for EUVL effects such as shadowing and flare. This study discusses aerial image formation through modeling of optical transfer function to assimilate optical diffraction, long range layout dependent flare effects, and shadowing effects due to non-telecentric imaging optics in the EUV case. Hence, after optimizing optical process parameters to model the EUV aerial image, this study will investigate OPC modeling methods employed to compensate these optical effects in the mask design flow.

A variety of micro scale surface wicking structures that form open/covered post surfaces and open channels are investigated to probe the effect of the geometry, inter-connectivity, and surface porosity on the wicking efficiency of such surfaces. The surfaces are examined using a capillary rise flow experiment and the study is focused on the Lucas-Washburn flow regime in which capillary forces balance viscous forces.

This study investigates various approaches to flare mitigation in EUVL. We evaluate the effectiveness of rule-based correction by defining a design where the critical dimension uniformity is used as a measure of the quality of the correction. We also describe the outcome of a model-based correction and the limits of this approach. Finally, we discuss the calculation of accurate full-chip flare maps which are required to implement a rule-based solution. Our results clearly indicate that it is possible to implement an effective flare variation compensation using rule-base correction with current EDA technology, provided that highly accurate full-chip flare maps having the required resolution are available.

Wicking structures based on interior corner geometry as the fundamental transport mechanism have been studied in microgravity environments. These structures provide for highly efficient passive transport that can be exploited in advanced two-phase passive cooling systems for applications in areas such as thermal control for microelectronics. Several pilot designs have been manufactured and tested and their performance is reported.

Dipole exposure techniques are currently being explored as alternatives to the low k1 problem that hinders the manufacture of sub 100nm logic technology. Recently, there has been a great deal of interest in using a combination of vertical and horizontal dipole exposures capable of producing manufacturing-robust image results for Manhattan features. In this technique, a design is split into two complementary masks that have enhanced contrast at a given dipole imaging condition. The dipole is a strong case of off-axis illumination, and significant resolution enhancement can be achieved, but only for one pattern direction. Complementary dipole exposures are required when dense pitches in horizontal and vertical direction are present. Dipole decomposition approaches that separate vertical and horizontal features in a layout are based on the fact that horizontal features form an improved aerial image with a vertical dipole illumination, and vertical features show the same aerial image improvement with a horizontal dipole illumination. This technique, though conceptually simple, requires a computer algorithm to decompose a design layout into two patterns consisting of features oriented mainly in the horizontal and vertical directions. Some layout features, landing pads or angled lines for example, cannot easily be assigned to a particular mask based on this simple orientation logic. In this work a new approach has been presented in which 45^o decomposition of the pattern is used to improve image contrast, pattern fidelity and focus behavior. The results will be analyzed in terms of contrast, pattern fidelity and focus dependence in order to determine the feasibility of printing manhattan and angled features using a dual dipole approach for sub 100nm processes.

In the modern photolithography simulation, the computation demand on resolution enhancement techniques (RETs) and optical proximity corrections (OPCs) is proportional to the simulation runtime of the model, which is dependant on the number of the kernels retained with the constrain of the model accuracy. Thus, it is essential to retain as few kernels as possible in the model calibration. Traditionally, the kernels are retained based upon their contribution to the aerial image, which is solely determined by the magnitudes of the eigenvalues. This method works well for arbitrary photolithography masks. However, real masks are never arbitrary and random. Instead, they have regular shapes and arrangements as governed by design rules, indicating the contributions from the retained kernels are statistically correlated to each other. By taking such correlations into account, the system representation can be improved to contain fewer kernels for a constant model accuracy. In this paper, the mathematical derivation of the pattern correlation concept is discussed and the concept is applied to a contact layer illuminated by a Quasar optical system with @l=193nm and NA=0.8. Significant improvement of model kernel representation is observed, four improved kernels vs 15 original kernels, and the new methodology is justified by comparing the difference of the aerial image intensities between the full kernel representation and the retained kernels representation at sampling points.

A new pattern analysis concept, referred to as a focus sensitivity model, has one output I"@D that identifies pattern components that are difficult to manufacture during photolithography. I"@D uses the change in modelled intensity with respect to defocus to rapidly determining if a pattern can be robustly manufactured. This paper will demonstrate that the I"@D model output can also be used on patterns without OPC to identify the same manufacturing characteristics found on a pattern that incorporates OPC. This is demonstrated by showing that OPC makes minor changes to the high spatial frequency components of a pattern. Current results show the I"@D analysis of a pattern that has OPC and the same pattern with no OPC is nearly qualitatively identical. The quantitative differences between the two outputs can be removed by changing the I"@D threshold value that is used to quantify pattern quality. However, the spatial frequency changes generated by other RET such as SRAFs is too large and non-linear to be compensated for with a simple change in the I"@D trigger threshold. The ability to remove the OPC correction set from pattern robustness analysis provides a significant advantage; even with the need to use other RET during robustness analysis.