Abstract: A first location within a mask pattern of a semiconductor circuit layout is determined, based on a feature of the mask pattern that is within a threshold distance of a boundary in the mask pattern. The mask pattern is based on a first mask exposure and a second mask exposure that meet at the boundary. The first location defines where to place a first assistive feature that reduces a sensitivity to lithographic process variations of the feature of the mask pattern. A second location of the mask pattern is also determined. The second location defines where to place a second assistive feature that reduces stray light at the boundary during the first mask exposure and the second mask exposure. The mask pattern is then modified to place the first assistive feature in the first location and the second assistive feature in the second location.

Abstract: In some aspects, a mask pattern is accessed. The mask pattern is for use in a lithography process that prints a pattern on a wafer. The mask pattern is applied as input to a deterministic model of the lithography process to predict a characteristic of the printed pattern. The deterministic model is deterministic, but it accounts for local stochastic variations of the characteristic in the printed pattern.

Abstract: Calibrating stochastic signals in compact modeling is provided by obtaining data of process variations in producing a resist mask; calibrating a continuous compact model of the resist mask based on the data; evaluating the continuous compact model against a stochastic compact model that is based on the data; choosing a functional description of an edge location distribution for the stochastic compact model; mapping image parameters from the evaluation to edge distribution parameters according to the functional description; determining an edge location range for the stochastic compact model based on scaled measurements from the image parameters; calibrating a threshold for the resist mask and updating parameters of the stochastic compact model to reduce a difference between the data and a modeled Line Edge Roughness (LER) value; and outputting the stochastic compact model.

Abstract: In some aspects, a mask pattern is accessed. The mask pattern is for use in a lithography process that prints a pattern on a wafer. The mask pattern is applied as input to a deterministic model of the lithography process to predict a characteristic of the printed pattern. The deterministic model is deterministic, but it accounts for local stochastic variations of the characteristic in the printed pattern.

Abstract: Calibrating stochastic signals in compact modeling is provided by obtaining data of process variations in producing a resist mask; calibrating a continuous compact model of the resist mask based on the data; evaluating the continuous compact model against a stochastic compact model that is based on the data; choosing a functional description of an edge location distribution for the stochastic compact model; mapping image parameters from the evaluation to edge distribution parameters according to the functional description; determining an edge location range for the stochastic compact model based on scaled measurements from the image parameters; calibrating a threshold for the resist mask and updating parameters of the stochastic compact model to reduce a difference between the data and a modeled Line Edge Roughness (LER) value; and outputting the stochastic compact model.