Photomask OPC Correction Prohibited Regions
Solution Overview
Problem
In the manufacturing of semiconductor devices, photomasks with hole and line features close to each other often result in unstable resist patterns due to optical proximity correction, leading to issues such as feature bonding or inaccurate drawing, which can violate mask rule checks and hinder the formation of desired resist patterns with sufficient depth of focus.
Innovation Solution
The method involves extracting proximity design features that are likely to be brought too close together during optical proximity correction, setting correction prohibited regions based on the wavelength of exposure light and numerical aperture of the exposure device, and excluding these regions from the correction process to prevent feature bonding and ensure stable pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If optical proximity correction is carried out to improve pattern accuracy, then the shape and dimensions of resist patterns can be corrected, but features close to each other are brought too close together causing unstable resolution and feature bonding
Solution Approach 1:
The patent applies preliminary action by performing mask rule check (MRC) before photomask manufacturing to identify features that will be brought too close together by optical proximity correction. Correction prohibited regions are set in advance based on MRC results, preventing the harmful effect of feature bonding while allowing beneficial OPC in safe regions.
Solution Approach 2:
The patent applies local quality by differentiating between regions where optical proximity correction should be applied and regions where it should be prohibited. Correction prohibited regions are locally identified around features close to each other based on MRC, while other regions continue to receive OPC benefits. This localized approach maintains pattern accuracy where safe and prevents instability where hazardous.
2Manufacturing precision
If features are brought closer together through optical proximity correction to achieve desired resist pattern, then pattern density is improved, but mask rule check is violated and depth of focus becomes insufficient
Solution Approach 1:
The patent performs mask rule check in advance to identify features that would result in insufficient depth of focus after OPC. Correction prohibited regions are established before photomask manufacturing based on MRC results, preventing the harmful effect of depth of focus insufficiency while maintaining pattern accuracy in regions where MRC passes.
3Manufacturing precision
If optical proximity correction is applied to all features, then overall pattern accuracy is improved, but processing time and computational complexity increase
Solution Approach 1:
The patent extracts and isolates features that would benefit from OPC without causing MRC violations. By identifying correction prohibited regions through MRC and excluding only those specific features from OPC, the patent maintains overall pattern accuracy while reducing unnecessary OPC processing time for features that would cause problems anyway.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the formation of desired resist patterns without violating mask rule checks, ensuring a sufficient depth of focus and improving the process margin in photoengraving by preventing feature bonding and maintaining pattern accuracy.
Implementation Method 1
a resist film for electron beam exposure over a light shield film formed over the surface of a glass plate is scanned with an electron beam based on the data and a layout pattern is thereby drawn
Implementation Method 2
photoengraving a predetermined pattern in a photosensitive material film over a semiconductor substrate
Data Source
AI summary
A manufacturing method of a photomask by which a resist pattern corresponding to a pattern with designed values can be formed, a method for optical proximity correction, and a manufacturing method of a semiconductor device are provided. Proximity design features that are close to each other and estimated to violate a mask rule check are extracted. In the proximity design features, correction prohibited regions where optical proximity correction is not carried out are set based on the distance between the features obtained from the extracted proximity design features and the resolution of an exposure device. Optical proximity correction is carried out on the proximity design features with the correction prohibited regions excluded to obtain corrected proximity patterns. A predetermined mask material is patterned by carrying out electron beam lithography based on the corrected proximity pattern data.