Abstract: One embodiment of the present invention provides a system that determines an assist feature placement within a post-optical proximity correction (post-OPC) mask layout. During operation, the system receives a set of target patterns which represent a set of polygons in a pre-OPC mask layout. The system then constructs a focus-sensitive cost function based on the target patterns, wherein the focus-sensitive cost function represents an amount of movement of post-OPC contours of the target patterns in response to changes in focus condition of the lithography system. Next, the system computes a cost-covariance field (CCF field) based on the focus-sensitive cost function, wherein the CCF field is a two-dimensional (2D) map representing changes to the focus-sensitive cost function due to an addition of a pattern at a given location within the post-OPC mask layout. Finally, the system generates assist features for the post-OPC mask layout based on the CCF field.

Abstract: Some embodiments provide techniques and systems to identify locations in a target mask layout for placing assist features. During operation, an embodiment can determine a spatial sampling frequency to sample the target mask layout, wherein sampling the target mask layout at the spatial sampling frequency prevents spatial aliasing in a gradient of a cost function which is used for computing an inverse mask field. Next, the system can generate a grayscale image by sampling the target mask layout at the spatial sampling frequency. The system can then compute the inverse mask field by iteratively modifying the grayscale image. The system can use the gradient of the cost function to guide the iterative modification process. Next, the system can filter the inverse mask field using a morphological operator, and use the filtered inverse mask field to identify assist feature locations in the target mask layout.

Abstract: One embodiment of the present invention provides a system that determines an assist feature placement within a post-optical proximity correction (post-OPC) mask layout. During operation, the system receives a set of target patterns which represent a set of polygons in a pre-OPC mask layout. The system then constructs a focus-sensitive cost function based on the target patterns, wherein the focus-sensitive cost function represents an amount of movement of post-OPC contours of the target patterns in response to changes in focus condition of the lithography system. Note that the contours of the target patterns substantially coincide with the edges of set of the polygons. Next, the system computes a cost-covariance field (CCF field) based on the focus-sensitive cost function, wherein the CCF field is a two-dimensional (2D) map representing changes to the focus-sensitive cost function due to an addition of a pattern at a given location within the post-OPC mask layout.

Abstract: One embodiment of the present invention provides a system that determines an assist feature placement within a post-optical proximity correction (post-OPC) mask layout. During operation, the system receives a set of target patterns which represent a set of polygons in a pre-OPC mask layout. The system then constructs a focus-sensitive cost function based on the target patterns, wherein the focus-sensitive cost function represents an amount of movement of post-OPC contours of the target patterns in response to changes in focus condition of the lithography system. Note that the contours of the target patterns substantially coincide with the edges of set of the polygons. Next, the system computes a cost-covariance field (CCF field) based on the focus-sensitive cost function, wherein the CCF field is a two-dimensional (2D) map representing changes to the focus-sensitive cost function due to an addition of a pattern at a given location within the post-OPC mask layout.

Abstract: One embodiment of the present invention provides a system that determines an assist feature placement within a post-optical proximity correction (post-OPC) mask layout. During operation, the system receives a set of target patterns which represent a set of polygons in a pre-OPC mask layout. The system then constructs a focus-sensitive cost function based on the target patterns, wherein the focus-sensitive cost function represents an amount of movement of post-OPC contours of the target patterns in response to changes in focus condition of the lithography system. Note that the contours of the target patterns substantially coincide with the edges of set of the polygons. Next, the system computes a cost-covariance field (CCF field) based on the focus-sensitive cost function, wherein the CCF field is a two-dimensional (2D) map representing changes to the focus-sensitive cost function due to an addition of a pattern at a given location within the post-OPC mask layout.

Abstract: One embodiment of the present invention provides a system that determines the locations and dimensions of one or more assist features in an uncorrected or corrected mask layout. During operation, the system receives a mask layout. The system then creates a set of candidate assist feature configurations, which specify locations and sizes for one or more assist features in the mask layout. Next, the system determines an improved assist feature configuration using the set of candidate assist feature configurations and a process-sensitivity model which can be represented by a multidimensional function that captures process-sensitivity information. Note that placing assist features in the mask layout based on the improved assist feature configuration improves the manufacturability of the mask layout. Moreover, using the process-sensitivity model to determine the improved assist feature configuration reduces the computational time required to determine the improved assist feature configuration in the mask layout.

Abstract: One embodiment of the present invention provides a system that determines an assist feature placement. During operation, the system receives an initial assist feature placement for a layout. Next, the system determines assist feature perturbations using the initial assist feature placement. An assist feature perturbation typically comprises a few simple polygons. The system then determines perturbation values at evaluation points in the layout using the assist feature perturbations and an analytical model. If a process-sensitivity model is used, the perturbation value at an evaluation point is associated with the change in the through-process window at that point in the layout. Next, the system determines a change in the value of an objective function using the perturbation values. The objective function can be indicative of the overall manufacturability of the layout. The system then determines an assist feature placement using the change in the value of the objective function.

Abstract: One embodiment of the present invention provides a system that identifies a problem edge in a mask layout which is likely to have manufacturing problems. During operation, the system creates an on-target process model that models a semiconductor manufacturing process under nominal process conditions. The system also creates one or more off-target process models that model the semiconductor manufacturing process under one or more process conditions that are different from nominal 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 an edge-detecting process-sensitivity model by convolving the process-sensitivity model with an edge-detecting function which can be used to detect edges in an image. Next, the system identifies a problem edge in the mask layout using the edge-detecting process-sensitivity model.

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 due to a missing or an improperly placed assist feature. During operation, the system receives an uncorrected or corrected mask layout. The system then dissects the mask layout into segments. Next, the system identifies a problem area associated with a segment using a process-sensitivity model which can be represented by a multidimensional function that captures process-sensitivity information. Note that identifying the problem area allows a new assist feature to be added or an existing assist feature to be adjusted, thereby improving the wafer manufacturability. Moreover, using the process-sensitivity model reduces the computational time required to identify the problem area.