Implicit function characterization of the curvilinear mask to realize parametric optical proximity correction with a neighborhood parallel tabu search.

The curvilinear mask structures provide significant benefits in improving lithographic resolution. Curvilinear masks, as opposed to rectilinear masks, have a wider range of structure types that can be used precisely to correct the contour of diffraction at sharp technological nodes. However, the curvilinear structure also makes the inverse design of mask in optical proximity correction (OPC) flow difficult.

Effective multi-objective inverse lithography technology at full-field and full-chip levels with a hybrid dynamic priority algorithm.

Inverse lithography technology (ILT), such as source mask optimization (SMO), is used to improve lithography performance. Usually, a single objective cost function is selected in ILT, and an optimal structure for one field point is achieved. The optimal structure is not the case for other images at full field points where the aberrations of the lithography system are different, even in high-quality lithography tools.

Spatial interpolation of regional PM concentrations in China during COVID-19 incorporating multivariate data.

During specific periods when the PM variation pattern is unusual, such as during the coronavirus disease 2019 (COVID-19) outbreak, epidemic PM regional interpolation models have been relatively little investigated, and little consideration has been given to the residuals of optimized models and changes in model interpolation accuracy for the PM concentration under the influence of epidemic phenomena. Therefore, this paper mainly introduces four interpolation methods (kriging, empirical Bayesian kriging, tensor spline function and complete regular spline function), constructs geographically weighted regression (GWR) models of the PM concentration in Chinese regions for the periods from January-June 2019 and January-June 2020 by considering multiple factors, and optimizes the GWR regression residuals using these four interpolation methods, thus achieving the purpose of enhancing the model accuracy. The PM concentrations in many regions of China showed a downward trend during the same period before and after the COVID-19 outbreak.

Sampling-based imaging model for fast source and mask optimization in immersion lithography.

Current source and mask optimization (SMO) research tends to focus on advanced inverse optimization algorithms to accelerate SMO procedures. However, innovations of forward imaging models currently attract little attention, which impacts computational efficiency more significantly. A sampling-based imaging model is established with the innovation of an inverse point spread function to reduce computational dimensions, which can provide an advanced framework for fast inverse lithography.

Vectorial pupil optimization to compensate for a polarization effect at full exposure field in lithography.

Recently, a single vectorial pupil optimization (VPO) was proposed to compensate for the polarization effect induced by thick mask and image optics at one field point in a lithography system, which does not work at full field points. In this paper, we propose a multi-objective VPO (MOVPO) method to obtain a universal vectorial pupil that can compensate for the polarization aberration at full field points. A novel multi-objective cost function, to the best of our knowledge, is built and includes uneven image pattern errors causing by polarization aberration (PA) at full field points in the MOVPO method.

Exposure latitude aware source and mask optimization for extreme ultraviolet lithography.

Extreme ultraviolet (EUV) lithography is a new generation of integrated circuit manufacturing technology with great development prospects. EUV lithography has more significant demand for high exposure latitude (EL) due to greater requirements for the stability of the light source. Source and mask optimization (SMO) technology is widely used to compensate for imaging distortion.

Ingestion of GNSS-Derived ZTD and PWV for Spatial Interpolation of PM Concentration in Central and Southern China.

With the increasing application of global navigation satellite system (GNSS) technology in the field of meteorology, satellite-derived zenith tropospheric delay (ZTD) and precipitable water vapor (PWV) data have been used to explore the spatial coverage pattern of PM concentrations. In this study, the PM concentration data obtained from 340 PM ground stations in south-central China were used to analyze the variation patterns of PM in south-central China at different time periods, and six PM interpolation models were developed in the region. The spatial and temporal PM variation patterns in central and southern China were analyzed from the perspectives of time series variations and spatial distribution characteristics, and six types of interpolation models were established in central and southern China.

Rigorous imaging-based measurement method of polarization aberration in hyper-numerical aperture projection optics.

Imaging-based measurement methods of polarization aberration (PA) are indispensable in hyper-numerical aperture projection optics for advanced lithography. However, the current methods are derived from the Kirchhoff model and ignore the 3D mask effect of the test mask, which will impact the measurement accuracy. In this paper, a novel imaging-based measurement method of PA is proposed based on a rigorous imaging model to improve the measurement accuracy.

Vectorial pupil optimization to compensate polarization distortion in immersion lithography system.

Polarization distortion innately exists in hyper numerical aperture immersion lithography system. Polarization distortion, mainly including polarization aberration (PA) of lithography projection optics and thick mask induced polarization distortion, would seriously impact on lithography imaging quality. Some computational lithography technologies, such as robust optical proximity correction and robust source and mask optimization, have been introduced and developed to reduce the impact of polarization distortion on lithography imaging.

Fast lithographic source optimization method of certain contour sampling-Bayesian compressive sensing for high fidelity patterning.

Fast source optimization (SO) is in demand urgently for holistic lithography on-line at 14-5 nm nodes. Our earlier works of fast compressive sensing (CS) SO methods adopted randomly sampling monitoring pixels on layout patterns, consequently resulting in failure of SO sometimes and poor image fidelity compared to gradient-based SO with complete sampling (SD-SO). This paper proposes a novel certain contour sampling-Bayesian compressive sensing SO (CCS-BCS-SO) method to achieve the goals of fast SO and high fidelity patterns simultaneously.

Multiple-field-point pupil wavefront optimization in computational lithography.

Some pupil wavefront optimization (PWO) approaches were studied to compensate the thick mask effects considering only a field point, and these PWO methods neglect the inherent wave aberration in a realistic lithography system. Particularly, the wave aberration of lithography projection optics is exposure field dependent, and the wave aberrations at different fields of view (FOVs) would seriously and unevenly impact the results and effects of PWO. The current PWO method for single FOV cannot match full FOV.

Multi-objective lithographic source mask optimization to reduce the uneven impact of polarization aberration at full exposure field.

Source and mask optimization (SMO) technology based on vectorial image model is indispensable in immersion lithography process at advanced technology node. Many kinds of algorithms have achieved successes in aspect of fast and robust SMO without accounting polarization aberration (PA). However, because the PA arising from immersion projection optics unevenly impacts on imaging performance, the conventional SMO would not be applicable in real lithography system.

Co-optimization method to reduce the pattern distortion caused by polarization aberration in anamorphic EUV lithography.

Extreme ultraviolet lithography is regarded as the most attractive technology to achieve 7 nm node and below. A new high-numerical-aperture anamorphic objective lens is designed to extend the single exposure resolution limit. However, the polarization aberrations (PAs) induced by the multilayer coatings on mirrors cause pattern distortions that cannot be neglected.

Fast nonlinear compressive sensing lithographic source and mask optimization method using Newton-IHTs algorithm.

Source and mask optimization (SMO) is an important method to improve lithography imaging fidelity. However, constrained by the computational inefficiency, the current SMO method can be used only in clip level applications. In this paper, to our best knowledge, the fast nonlinear compressive sensing (CS) theory is for the first time applied to solve the nonlinear inverse reconstruction problem in SMO.

A nonlinear measurement method of polarization aberration in immersion projection optics by spectrum analysis of aerial image.

Polarization aberrations (PA) can be presented by Jones pupil and can also impact the imaging performance of immersion projection optics significantly. Precise PA measurement is most important for resolution enhancement technology and holistic lithography at 7nm node and below, in order to improve the pattern fidelity and processing stability. However, the current imaging-based measurement method of PA by linear approximation has not taken the coupling effect of the PA coefficients into account.