Abstract: A method is described for designing an alternating phase shifted mask (altPSM) by optimally selecting the width of phase shapes. The selection of optimal phase shape widths is achieved by providing a lithography metric that describes the relationship between phase shape width and the target image dimension such that the metric, such as process window or across chip linewidth variation (ACLV), is optimized. In a preferred embodiment, ACLV is computed by Monte Carlo simulation by providing a set of error distributions for lithographic parameters such as focus, dose, lens aberrations, and the like. Alternatively, a lookup table of optimal phase widths associated with target image dimensions may be provided. The resulting altPSM is characterized by phase shapes having widths that vary according to the widths of the target image dimensions.

Abstract: A method is provided for designing an altPSM mask including a substrate. The method includes the following steps. Provide a circuit layout. Identify critical elements of the circuit layout. Provide a cutoff layout dimension. Identify critical segments of the circuit layout which are critical elements with a sub-cutoff dimension less than the cutoff dimension. Create basic phase shapes associated with the critical segments. Remove layout violations from the phase shapes. Determine whether the widths of phase shapes associated with a critical segment have unequal narrower and wider widths. If YES, then widen each narrower phase shape to match the width of wider phase shape associated with the critical segment and repeat the steps starting with removal of layout violations until the test answer is NO. When the test answer is NO, provide a layout pattern to an output.

Abstract: A method and apparatus for making phase shift masks are provided wherein an anti-reflective coating used on an opaque pattern layer of the mask fully covers the opaque pattern layer and has not been etched in the etching process to form the phase shift mask. A two-exposure method to form the phase shift mask is used wherein a photoresist having a defined dose-to-clear level is coated on the surface of the mask and the lower surface of the mask is exposed to a blanket exposure in an energy amount less than the dose-to-clear level. The open areas of the upper surface of the mask to be etched are exposed to an energy dose in an amount less than the dose-to-clear level, with the sum of the amounts of the lower surface energy and upper surface energy being at least the dose-to-clear level. The method and apparatus minimizes and/or avoids etching of the anti-reflective coating.

Abstract: A method and computer program product is described for optimizing the design of a circuit layout that assigns binary properties to the design elements according to a hierarchy of rules. For example, the design of an alternating phase shifted mask (altPSM) is optimized first according to rules that assign phase shapes that maximize image quality for critical circuit elements, and then further optimized to minimize mask manufacturability problems without significantly increasing the complexity of the design process flow. Further optimization of the design according to additional rules can be performed in a sequentially decreasing priority order. As the priority of rules decrease, some violation of lower priority rules may be acceptable, as long as higher priority rules are not violated.

Abstract: A method and computer program product is described for optimizing the design of a circuit layout that assigns binary properties to the design elements according to a hierarchy of rules. For example, the design of an alternating phase shifted mask (altPSM) is optimized first according to rules that assign phase shapes that maximize image quality for critical circuit elements, and then further optimized to minimize mask manufacturability problems without significantly increasing the complexity of the design process flow. Further optimization of the design according to additional rules can be performed in a sequentially decreasing priority order. As the priority of rules decrease, some violation of lower priority rules may be acceptable, as long as higher priority rules are not violated.

Abstract: A method and computer program product is described for optimizing the design of a circuit layout that assigns binary properties to the design elements according to a hierarchy of rules. For example, the design of an alternating phase shifted mask (altPSM) is optimized first according to rules that assign phase shapes that maximize image quality for critical circuit elements, and then further optimized to minimize mask manufacturability problems without significantly increasing the complexity of the design process flow. Further optimization of the design according to additional rules can be performed in a sequentially decreasing priority order. As the priority of rules decrease, some violation of lower priority rules may be acceptable, as long as higher priority rules are not violated.

Abstract: A method is described for designing an alternating phase shifted mask (altPSM) by optimally selecting the width of phase shapes. The selection of optimal phase shape widths is achieved by providing a lithography metric that describes the relationship between phase shape width and the target image dimension such that the metric, such as process window or across chip linewidth variation (ACLV), is optimized. In a preferred embodiment, ACLV is computed by Monte Carlo simulation by providing a set of error distributions for lithographic parameters such as focus, dose, lens aberrations, and the like. Alternatively, a lookup table of optimal phase widths associated with target image dimensions may be provided. The resulting altPSM is characterized by phase shapes having widths that vary according to the widths of the target image dimensions.