Adaptive Window Feature Density Computation for Chip Layouts
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Solution Overview
Problem
Current methods for computing feature density in semiconductor chip layouts face a tradeoff between accuracy and computational time, as decreasing step size increases accuracy but also increases time, while increasing step size reduces accuracy and improves speed.
Innovation Solution
A system that computes feature density by dynamically adjusting the window displacement based on the feature density value and design thresholds, allowing for accurate identification of design rule violations with optimized computational efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the step size is decreased to increase accuracy, then the measurement precision of feature density improves, but the computational time increases
Solution Approach 1:
The patent applies dynamics by making the step size adaptive rather than fixed. The step size is dynamically adjusted based on the current feature density value and the design rule threshold. When the current density is close to the threshold, smaller steps are used to maintain accuracy. When the density is far from the threshold, larger steps are used to reduce computational time. This dynamic adjustment resolves the contradiction between measurement precision and computational time.
Solution Approach 2:
The patent changes the parameter of step size based on the relationship between the current feature density and the design rule threshold. The step size is calculated as a function of the difference between the current density and the threshold, allowing the measurement parameter to vary adaptively. This parameter change enables the system to achieve high accuracy where needed while maintaining efficiency where the threshold is not critical.
2Productivity
If the step size is increased to reduce computational time, then the productivity improves, but the measurement precision of feature density decreases
Solution Approach 1:
The system dynamically adjusts the step size based on the proximity to the design rule threshold. When the current feature density is far from the threshold, the system uses larger steps to maximize computational efficiency. When the density approaches the threshold, the system automatically reduces the step size to maintain measurement precision for detecting violations. This dynamic behavior resolves the contradiction between productivity and measurement precision.
Solution Approach 2:
The step size parameter is changed adaptively based on the current density value and threshold relationship. The patent calculates the step size as a function of the difference between current density and threshold, allowing larger steps when the difference is large (improving productivity) and smaller steps when the difference is small (maintaining precision). This parameter adaptation simultaneously achieves high productivity and measurement precision.
3Device complexity
If a fixed step size is used to simplify the computation, then the device complexity is reduced, but the adaptability to different density regions is lost
Solution Approach 1:
The patent replaces the static fixed step size with a dynamic adaptive step size that automatically adjusts based on the local feature density and its relationship with the design rule threshold. This dynamic approach increases adaptability to different density regions while maintaining reasonable computational complexity through a systematic adaptation rule rather than complex decision-making logic.
Solution Approach 2:
The step size parameter is changed adaptively based on the current density and threshold relationship, allowing the system to automatically adjust to different regions of the layout. This parameter change enables the system to detect violations in both high-density and low-density regions effectively, improving adaptability without requiring region-by-region manual configuration.
Data Source
AI summary
One embodiment of the present invention provides a system that computes feature density for a number of areas within a layout by moving a window across the layout, which allows the system to identify areas in the layout that violate a design rule. During operation, the system receives a layout. Next, the system places the window at a first location in the layout. The system then computes the feature density value based on the features within the window at the first location. Next, the system determines a second location in the layout based on the first location and the feature density value. The system then moves the window to the second location. Next, the system computes the feature density value based on the features within the window at the second location. Note that determining the second location in the layout based on the feature density value computed at the first location instead of using a constant displacement from the first location allows the system to accurately identify an area that violates the design rule.