Abstract: A lithography model uses a transfer function to map exposure energy dose to the thickness of remaining photoresist after development; while allowing the flexibility to account for other physical processes. In one approach, the model is generated by fitting empirical data. The model may be used in conjunction with an aerial image to obtain a three-dimensional profile of the remaining photoresist thickness after the development process. The lithography model is generally compact, yet capable of taking into account various physical processes associated with the photoresist exposure and/or development process for more accurate simulation.

Abstract: One embodiment of the present invention provides techniques and systems for determining modeling parameters for a photolithography process. During operation, the system can receive a layout. Next, the system can determine an iso-focal pattern in the layout. The system can then determine multiple aerial-image-intensity values in proximity to the iso-focal pattern by convolving the layout with multiple optical models, wherein the multiple optical models model the photolithography process's optical system under different focus conditions. Next, the system can determine a location in proximity to the iso-focal pattern where the aerial-image-intensity values are substantially insensitive to focus variations. The system can then use the location and the associated aerial-image-intensity values to determine an optical threshold and a resist bias. The optical threshold and the resist bias can then be used for modeling the photolithography process.

Abstract: One embodiment provides a system for determining a process model for a photolithography process. The photolithography process can use multiple exposure-and-development steps to create features on a wafer. When the photolithography process exposes the wafer to a layout, the wafer can include topography variations which were caused by previous exposure-and-development steps. The process model can be used to predict patterns that are created on the wafer when the wafer is exposed to a second layout, wherein the wafer includes topography variations that were caused by resist features that were created when the wafer was exposed to a first layout. The process model can include a first term and a second term, wherein the first term is convolved with a sum of the first layout and the second layout, and wherein the second term is convolved with the second layout.

Abstract: Some embodiments provide techniques for determining a set of Abbe's kernels which model an optical system of a photolithography process. During operation, the system can receive optical parameters (e.g., numerical aperture, wavelength, etc.) for the photolithography process's optical system. Next, the system can use the optical parameters to determine a point spread function for an Abbe's source. Note that the point spread function for the Abbe's source can be determined either by discretizing the optical system's light source using a set of concentric circles, or by discretizing the optical system's light source in an orthogonal fashion. The system can then determine a correlation matrix from the point spread function. Next, the system can determine the set of Abbe's kernels by performing an eigen decomposition of the correlation matrix using principal component analysis. The system can then use the set of Abbe's kernels to compute image intensity.

Abstract: A lithography model uses a transfer function to map exposure energy dose to the thickness of remaining photoresist after development; while allowing the flexibility to account for other physical processes. In one approach, the model is generated by fitting empirical data. The model may be used in conjunction with an aerial image to obtain a three-dimensional profile of the remaining photoresist thickness after the development process. The lithography model is generally compact, yet capable of taking into account various physical processes associated with the photoresist exposure and/or development process for more accurate simulation.

Abstract: One embodiment of the present invention provides a method to facilitate using a synchrotron as a source in an extreme ultraviolet lithography (EUVL) system, wherein the synchrotron's energy decreases over time. The EUVL system can includes a stepper which uses a step-and-repeat process or a step-and-scan process to transfer patterns from a reticle onto a wafer. The wafer is desired to be exposed to a substantially constant dose. During operation, the system can measure a synchrotron current, and adjust the stepper's exposure duration or the stepper's scan speed based on the synchrotron current so that the wafer is exposed to the substantially constant dose. Note that using the synchrotron current to control the stepper can enable the EUVL system to expose the wafer to the substantially constant dose without using additional equipment to monitor the source's energy.

Abstract: One embodiment of the present invention provides techniques and systems for modeling long-range extreme ultraviolet lithography (EUVL) flare. During operation, the system may receive an evaluation point in a layout. Next, the system may receive an EUVL model which includes kernels that are discretized at different sampling rates, and which have different sized ambits. Specifically, a kernel that is discretized using a low sampling rate may have a longer range than a kernel that is discretized using a high sampling rate. The system may then convolve the kernels with the layout at the evaluation point over their respective ambits. Next, the system may use the convolution results to determine an indicator value. The indicator value can be used for a number of applications, e.g., to predict pattern shapes that are expected to print on a wafer, to perform optical proximity correction, or to identify manufacturing problem areas in the layout.

Abstract: One embodiment of the present invention provides a system that reduces computational complexity in simulating an image resulting from an original mask and an optical transmission system. During operation, the system obtains a set transmission cross coefficient (TCC) kernel functions based on the optical transmission system, and obtains a set of transmission functions for a representative pattern which contains features representative of the original mask. The system constructs a new set of kernel functions based on the TCC kernel functions and the transmission functions for the representative pattern, wherein responses to the new kernel functions in a resulting image corresponding to the representative pattern are substantially uncorrelated with one another. The system further produces an intensity distribution of a resulting image corresponding to the original mask based on the new kernel functions, thereby facilitating prediction of a layout that can be produced from the original mask.

Abstract: An embodiment provides systems and techniques for determining a process model. During operation, the system may receive a first optical model which models a first optical system of a photolithography process. Next, the system may use the first optical model to determine a second optical model that models a second latent image that is formed by the first optical system at a second distance. The system may also use the first optical model to determine a third optical model that models a third latent image that is formed by the first optical system at a third distance. Next, the system may receive process data which is obtained by subjecting a test layout to the photolithography process. The system may then determine a process model using the first optical model, the second optical model, the third optical model, the test layout, and the process data.

Abstract: One embodiment provides a system for using a database to quickly identify a manufacturing problem area in a layout. During operation, the system receives a first check-figure which identifies a first area in a first layout, wherein the first area is associated with a first feature. Next, the system determines a first sample using the first check-figure, wherein the first sample represents the first layout's geometry within a first ambit of the first check-figure, wherein the first sample's geometry is expected to affect the shape of the first feature. The system then performs a model-based simulation using the first sample to obtain a first simulation-result which indicates whether the first feature is expected to have manufacturing problems. Next, the system stores the first simulation-result in a database which is used to quickly determine whether a second feature is expected to have manufacturing problems.

Abstract: An embodiment provides systems and techniques for determining an improved process model which models mask corner rounding (MCR) effects. During operation, the system may receive a mask layout and process data which was generated by applying a photolithography process to the mask layout. The system may also receive an uncalibrated process model which may contain a set of MCR components. Next, the system may identify a set of corners in the mask layout. The system may then determine a set of mask layers, wherein at least some of the mask layers correspond to the MCR components. Next, the system may determine an improved process model by calibrating the uncalibrated process model using the set of mask layers, and the process data.

Abstract: One embodiment provides a system that can enable a designer to determine the effects of subsequent processes at design time. During operation, the system may receive a test layout and an optical model that models an optical system, but which does not model the effects of subsequent processes, such as optical proximity correction (OPC). The system may generate a first dataset using the test layout and the optical model. Next, the system may apply OPC to the test layout, and generate a second dataset using the corrected test layout and the optical model. The system may then use the first dataset and the second dataset to adjust the optical model to obtain a second optical model that models the effects of subsequent processes.

Abstract: An embodiment provides systems and techniques for determining a process model. During operation, the system may receive a first optical model which models a first optical system of a photolithography process. Next, the system may use the first optical model to determine a second optical model that models a second latent image that is formed by the first optical system at a second distance. The system may also use the first optical model to determine a third optical model that models a third latent image that is formed by the first optical system at a third distance. Next, the system may receive process data which is obtained by subjecting a test layout to the photolithography process. The system may then determine a process model using the first optical model, the second optical model, the third optical model, the test layout, and the process data.

Abstract: One embodiment of the present invention provides a system that identifies an area in a mask layout which is likely to cause manufacturing problems. During operation, the system creates an on-target process model that models a semiconductor manufacturing process under nominal (e.g., optimal) process conditions. The system also creates one or more off-target process models that model the semiconductor manufacturing process under one or more arbitrary (e.g., non-optimal) process conditions. Next, the system computes a process-sensitivity model using the on-target process model and the off-target process models. The system then computes a gradient-magnitude of the process-sensitivity model. Next, the system identifies a problem area in the mask layout using the gradient-magnitude of the process-sensitivity model. Note that identifying the problem area allows it to be corrected, which improves the manufacturability of the mask layout.

Abstract: Some embodiments provide techniques for determining a set of Abbe's kernels which model an optical system of a photolithography process. During operation, the system can receive optical parameters (e.g., numerical aperture, wavelength, etc.) for the photolithography process's optical system. Next, the system can use the optical parameters to determine a point spread function for an Abbe's source. Note that the point spread function for the Abbe's source can be determined either by discretizing the optical system's light source using a set of concentric circles, or by discretizing the optical system's light source in an orthogonal fashion. The system can then determine a correlation matrix from the point spread function. Next, the system can determine the set of Abbe's kernels by performing an eigen decomposition of the correlation matrix using principal component analysis. The system can then use the set of Abbe's kernels to compute image intensity.

Abstract: An embodiment provides systems and techniques for determining a process model. During operation, the system may receive a first optical model which models a first optical system of a photolithography process. Next, the system may use the first optical model to determine a second optical model that models a second latent image that is formed by the first optical system at a second distance. The system may also use the first optical model to determine a third optical model that models a third latent image that is formed by the first optical system at a third distance. Next, the system may receive process data which is obtained by subjecting a test layout to the photolithography process. The system may then determine a process model using the first optical model, the second optical model, the third optical model, the test layout, and the process data.

Abstract: One embodiment provides a method to determine if a pattern is robustly manufacturable. During operation, the system may receive a first pattern and a design intent, wherein the first pattern is intended to generate the design intent. Next, the system may determine a second pattern using the design intent, wherein subjecting the second pattern to a second manufacturing process is expected to generate a third pattern that is substantially similar to the design intent. The system may then determine if a first semiconductor manufacturing process is capable of robustly manufacturing the second pattern. If the second pattern is not robustly manufacturable, the system may generate an indicator that indicates that the first pattern is not robustly manufacturable.

Abstract: One embodiment provides a system for determining an improved process model that models one or more semiconductor manufacturing processes. During operation, the system can receive a first process model. Next, the system can receive a 2-D-pattern detecting kernel which can detect 2-D patterns. The system can then receive a second set of empirical data which is associated with 2-D patterns in a test layout. Next, the system can determine an improved process model using the first process model, the 2-D-pattern detecting kernel, the test layout, and the second set of empirical data.

Abstract: An embodiment provides systems and techniques for determining an improved process model which models mask corner rounding (MCR) effects. During operation, the system may receive a mask layout and process data which was generated by applying a photolithography process to the mask layout. The system may also receive an uncalibrated process model which may contain a set of MCR components. Next, the system may identify a set of corners in the mask layout. The system may then determine a set of mask layers, wherein at least some of the mask layers correspond to the MCR components. Next, the system may determine an improved process model by calibrating the uncalibrated process model using the set of mask layers, and the process data.

Abstract: One embodiment of the present invention provides a system that determines whether a sub-resolution assist feature will print. During operation, the system receives a layout which contains a sub-resolution assist feature. Next, the system determines whether the sub-resolution assist feature will print using a process model and the layout. The process model is determined using first process data and second process data. The first process data is obtained using a first layout which is exposed using a first exposure level. The second process data is obtained using a second layout which is exposed using a second exposure level, which is different from the first exposure level. The second exposure level causes the sub-resolution assist features within the second layout to print.