Lithography Mask Assist Pattern for OPE Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The optical proximity effect (OPE) in semiconductor manufacturing leads to pattern deviations, such as rounded corners and line width variations, due to diffraction and interference when the pitch of mask patterns is scaled down, affecting the resolution and integrity of transferred patterns on photoresist layers.
Innovation Solution
A mask with an assist pattern is used, where the assist pattern is disposed in a second strip pattern neighboring a first strip pattern, with a width larger than the first strip pattern, to adjust light intensity and prevent micro-loading effects, ensuring uniform light transmission and improved pattern correctness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pitch of mask patterns is scaled down to achieve finer device integration, then the integration density is improved, but diffraction and interference occur causing pattern resolution degradation
Solution Approach 1:
The patent introduces assist patterns as intermediary elements positioned between transparent regions of different interval sizes. These assist patterns act as mediators that transfer optical energy to compensate for diffraction and interference effects, enabling finer pitch patterns to be resolved accurately without sacrificing pattern quality
2Manufacturing precision
If dummy patterns or scattering bars are added to prevent OPE effects, then pattern integrity is improved, but the feasible utilization rate of semiconductor wafer decreases
Solution Approach 1:
The patent applies local quality by placing assist patterns only in specific locations where optical proximity effects are problematic - namely between transparent regions of different interval sizes. This localized approach provides pattern integrity enhancement only where needed, avoiding the wafer utilization penalty associated with blanket dummy patterns or scattering bars across the entire mask
3Manufacturing precision
If light passes through transparent regions with small interval sizes, then fine pattern transfer is enabled, but micro-loading effect occurs causing pattern deformation
Solution Approach 1:
The assist patterns serve as optical intermediaries that redirect light energy from transparent regions with small interval sizes to adjacent regions. This mediation balances the light distribution across different transparent regions, preventing micro-loading effects while preserving the ability to transfer fine patterns accurately
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
The assist pattern enhances the accuracy and integrity of the transferred pattern by uniformizing light intensity across the first strip pattern, reducing pattern deformations and maintaining the correctness of the formed pattern, even at smaller feature sizes.
Implementation Method 1
the assist pattern is used to make uniform quantity of light passing through two sides of the first strip pattern in the lithography process
Implementation Method 2
when the light passes through the mask, diffraction and interferences may occur
Implementation Method 3
when the light passes through the mask, diffraction and interferences may occur
Data Source
AI summary
A method of forming a pattern is disclosed. At first, a layout pattern is provided to a computer system. The layout pattern includes at least a first strip pattern and at least a second strip pattern, and a width of the second strip pattern is substantially larger than a width of the first strip pattern. Subsequently, the second strip pattern neighboring the first strip pattern is defined as a selected pattern. Then, an assist pattern is formed in the selected pattern, and the assist pattern does not overlap a center line of the selected pattern. The layout pattern and the assist pattern are further outputted through the computer system onto a mask.