Patent ID: 7824842
Filing Date: 2010-11-02
Classification: G03F

Abstract:
1. A method of patterning a positive tone resist layer overlaying at least partially a lithographic substrate with a target pattern of target pattern features and spaces having a target duty cycle of feature-width divided by pitch, comprising: providing a mask pattern of mask-pattern features and spaces in accordance with the target pattern using a patterning device, and having a mask-pattern duty cycle of feature-width divided by pitch; exposing the positive tone resist layer to a pattern of radiation using the mask pattern, wherein the patterning device and a projection system having a demagnification factor are traversed by the radiation and are constructed and arranged to provide said pattern of radiation; selecting a bias-ratio of mask-pattern feature-width multiplied by demagnification and divided by target-pattern feature-width at a value lower than 0.8; and arranging an exposure dose in accordance with the selected bias-ratio to provide the target duty cycle.