Curvilinear OPC Control Point Shifting for Edge Placement Error
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Solution Overview
Problem
Existing optical proximity correction (OPC) methods struggle to minimize edge placement errors (EPE) effectively, especially at corner portions of patterns in semiconductor manufacturing.
Innovation Solution
The proposed OPC method involves generating a retarget curve line for a polygonal pattern layout, shifting control points along this curve to minimize EPE, and iteratively refining the curvilinear pattern layout through simulation and adjustment until the desired edge placement accuracy is achieved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional OPC methods are used to correct patterns, then manufacturing precision is improved, but edge placement error at corner portions cannot be sufficiently minimized
Solution Approach 1:
The patent divides the pattern correction process into multiple stages: initial control points are generated on the retarget curve line, then iteratively adjusted by shifting along the curve. The corner portions are specifically targeted through segmentation of the control points into multiple groups, with each group independently optimized. This segmentation enables precise control of corner regions while maintaining overall pattern accuracy.
Solution Approach 2:
The patent introduces a new dimension of control by allowing control points to shift not only in the normal direction but also along the retarget curve line. This additional degree of freedom enables optimization of corner portions where traditional normal-direction adjustment is insufficient. The control points can move in multiple directions (along the curve and perpendicular to it), providing enhanced flexibility for correcting complex corner geometries.
2Manufacturing precision
If control points are shifted along the retarget curve line to minimize EPE, then manufacturing precision is improved, but computational complexity increases
Solution Approach 1:
The patent performs preliminary actions by pre-calculating the retarget curve line and initial control points before the iterative optimization process. The retarget curve line is generated based on the desired pattern geometry, and initial control points are positioned on this pre-computed curve. This preliminary preparation reduces the computational burden during the iterative EPE minimization process, as the optimization only needs to adjust control points along the pre-defined curve rather than generating everything from scratch.
Solution Approach 2:
The patent implements a feedback mechanism where the edge placement error (EPE) is calculated after each iteration, and the control points are adjusted based on this feedback. The process continuously monitors the difference between the current pattern and the target pattern, making iterative adjustments to minimize EPE. This feedback loop ensures that computational resources are efficiently allocated to adjustments that actually improve accuracy, avoiding unnecessary computations.
3Manufacturing precision
If multiple control points are generated and adjusted iteratively, then manufacturing precision is improved, but processing time increases
Solution Approach 1:
The patent applies local quality by treating different regions of the pattern with different levels of refinement. Corner portions, which are more difficult to correct, receive specialized attention with multiple control points and iterative adjustment, while straighter regions use fewer control points. This localized approach ensures high precision where needed without unnecessarily increasing processing time for simpler regions.
Solution Approach 2:
The patent introduces dynamic adjustment of control points during the optimization process. Rather than using a fixed set of control points, the system dynamically positions control points along the retarget curve line based on the current EPE measurements. This dynamic approach allows the system to adaptively allocate computational resources, focusing iterations on regions that require the most correction while reducing effort in regions that are already well-aligned.
Data Source
AI summary
An optical proximity correction (OPC) method includes generating a retarget curve line of a polygonal pattern layout of a target pattern, generating first control points on the retarget curve line, generating a first curvilinear pattern layout based on the first control points, extracting a contour of the target pattern through a OPC simulation, calculating an edge placement error, determining whether to re-perform the extracting, when it is determined to re-perform the extracting of the contour, shifting the first control points to second control points, and when it is determined not to re-perform the extracting, determining the first curvilinear pattern layout as an OPCed layout. In the shifting, a first starting control point is shifted in a first direction different from a normal direction. After the shifting, the generating of the first curvilinear pattern layout is performed based on the second control points to generate a second curvilinear pattern layout.