Inverse lithography for high transmission attenuated phase shift mask design and creation
AssigneeImec
InventorsEric Henri Jan Hendrickx, Alexander V. Tritchkov, Kyohei Sakajiri
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Abstract
Various implementations of the invention provide for generation of a high transmission phase shift mask layout through inverse lithography techniques. In various implementations of the present invention, a set of mask data having a plurality of pixels is generated. The transmission value associated with each pixel may then be determined through an inverse lithography technique. With various implementations of the invention, the inverse lithography technique identifies an objective function, minimizes the objective function in relation to a simulation of the optical lithographic process, such that the transmission value, which is greater than 6%, may be determined.
Claims21
A method of generating photolithographic mask data for a mask, the method comprising:
- identifying a target image, the target image corresponding to an image to be printed onto a substrate through an optical lithographic process;
- generating a set of mask data for an attenuated phase shift mark, the mask comprising:
- a main feature having a transmission value of 100%, the main feature comprising an isolated pattern and corresponding to a feature on the target image,
- a plurality of assist features surrounding the main feature and having a linewidth substantially smaller than a linewidth of the main feature, the assist features having a transmission value of 100%, and
- a plurality of phase shift areas having a transmission value of greater than 6%;
- simulating by a computer an intensity on a substrate generated by employment of the set of mask data in the optical lithographic process;
- identifying an objective function that compares the simulation of the intensity to an ideal image intensity corresponding to the target image;
- and
- minimizing an intensity on the substrate outside the main feature based on the objective function to determine a placement for the plurality of assist features in the set of mask data.
A non-transitory computer readable storage medium having stored thereon instructions which, when executed on a computer, causes the computer to perform a method, the method comprising:
- identifying a target image, the target image corresponding to an image to be printed onto a substrate through an optical lithographic process;
- generating a set of mask data for an attenuated phase shift mask, the mask comprising:
- a main features having a transmission value of 100%, the main feature comprising an isolated pattern and corresponding to a feature on the target image, a plurality of assist features surrounding the main feature and having a linewidth substantially smaller than a linewidth of the main feature, the assist features having a transmission value of 100%, and a plurality of phase shift areas having a transmission value of greater than 6%;
- simulating an intensity on a substrate generated by employment of the set of mask data in the optical lithographic process;
- identifying an objective function that compares the simulation of the intensity to an ideal image intensity corresponding to the target image;
- minimizing an intensity on the substrate outside the main feature based on the objective function to determine a placement for the plurality of assist features in the set of mask data;
- and
- saving the mask data to a memory storage location.
Dependencies are inferred from the claim text.