Curvilinear Layout Retargeting With Spline Anchor Point Adjustment
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Solution Overview
Problem
Conventional retargeting techniques struggle to effectively process curvilinear layout features in circuit design, leading to issues such as fragment degeneration and poor lithographic quality, especially when applied to silicon photonics and memory chip manufacturing.
Innovation Solution
A method involving selecting anchor points on layout features, determining property values, adjusting their positions using splines, and deriving retargeted layout features through interpolating or approximating curves, followed by optical proximity correction to generate mask data for photomasks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional retargeting techniques are applied to curvilinear layout features, then processing capability is maintained, but lithographic quality deteriorates and fragment degeneration occurs
Solution Approach 1:
The curvilinear boundary is segmented into multiple discrete anchor points that are selected based on curvature conditions. This segmentation allows the complex curve to be processed as a series of manageable points, preventing fragment degeneration while maintaining lithographic quality.
Solution Approach 2:
Anchor points are selectively placed based on local curvature conditions - denser spacing in high-curvature regions and sparser spacing in low-curvature regions. This local adaptation ensures high pattern fidelity where needed while maintaining overall processing efficiency.
2Ease of manufacture
If Manhattan shapes are used in layout design, then conventional DRC and OPC tools work effectively, but lithographic quality and design flexibility are limited
Solution Approach 1:
The invention transitions from straight-edged Manhattan shapes to curvilinear boundaries with smooth curves. This curvature enables better lithographic quality by reducing diffraction effects and improving pattern fidelity, while the systematic anchor point method ensures compatibility with conventional processing tools.
3Manufacturing precision
If curvilinear patterns are introduced to improve lithographic quality, then pattern fidelity is enhanced, but conventional retargeting tools fail to process them effectively
Solution Approach 1:
The anchor points serve as an intermediary representation between the curvilinear boundary and the retargeting process. By converting the continuous curve into discrete anchor points with specific selection conditions, the method enables conventional tools to effectively process curvilinear patterns without losing lithographic quality.
4Productivity
If feature size is reduced to increase circuit density, then more components fit on substrate, but image reproduction fidelity deteriorates and manufacturing flaws increase
Solution Approach 1:
The invention changes the geometric parameters of layout features from Manhattan shapes to curvilinear shapes with optimized anchor point distributions. This parameter change improves image reproduction fidelity at reduced feature sizes by reducing diffraction effects and improving light transmission characteristics during photolithography.
Data Source
AI summary
Various aspects of the present disclosed technology relate to techniques for retargeting free-form layout features. In a retargeting process, anchor points are selected on boundary lines of layout features based on one or more predetermined conditions. Property values comprising spacing values and linewidth values for each of the anchor points are then determined. Based on the determined property values, positions of the anchor points are adjusted to derive new anchor points. Retargeted layout features are derived by using splines as interpolating curves passing through the new anchor points or as approximating curves passing near to but not necessarily through the new anchor points.