Dummy Pattern Layout With Density Gradients for Wafer Flatness
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Solution Overview
Problem
Current systems face challenges in achieving high surface uniformity on semiconductor wafers due to erosion and dishing effects during chemical mechanical polishing, which are exacerbated by abrupt density changes caused by incomplete dummy pattern placement in vacant regions.
Innovation Solution
A system and method for designing dummy pattern layouts that involve identifying feature patterns, determining properties and rules based on scripts, and generating dummy patterns with controllable density gradients through wrap-filling techniques to ensure gradual density changes across the wafer surface, thereby reducing erosion and dishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dummy patterns are placed in vacant regions to improve surface flatness, then surface uniformity is improved, but abrupt density changes occur causing erosion and dishing effects
Solution Approach 1:
The patent applies local quality by varying the density of dummy patterns in different regions. Specifically, the density of dummy patterns is adjusted based on the distance from feature patterns, creating a gradient distribution where density is higher near feature patterns and lower in distant vacant regions. This local variation in density prevents abrupt transitions and reduces erosion and dishing effects during chemical mechanical polishing.
Solution Approach 2:
The patent changes the density parameter of dummy patterns to resolve the contradiction. By controlling the density gradient of dummy patterns based on distance from feature patterns, the system maintains surface flatness while avoiding abrupt density changes that cause erosion and dishing. The density parameter is specifically adjusted to create a smooth transition zone between feature patterns and vacant regions.
2Manufacturing precision
If dummy patterns are densely filled in vacant regions, then surface uniformity is improved, but pattern distortion increases due to excessive density
Solution Approach 1:
The patent applies local quality by making the density of dummy patterns location-dependent. Dummy patterns closer to feature patterns have higher density to maintain surface uniformity, while those farther away have lower density to prevent pattern distortion. This spatially varying density approach ensures both surface uniformity and pattern integrity.
Solution Approach 2:
The patent introduces dynamics by making the dummy pattern density adaptive rather than static. The density is determined dynamically based on the distance from feature patterns, allowing the system to optimize both surface uniformity and pattern shape preservation according to local conditions in the layout.
3Manufacturing precision
If manual dummy pattern placement is used, then precise control over density is achieved, but design complexity and time increase
Solution Approach 1:
The patent applies self-service by enabling the dummy pattern generation system to automatically determine optimal density distributions based on the layout geometry. The system calculates density gradients and places dummy patterns autonomously using algorithms that consider distance from feature patterns, eliminating the need for manual intervention while maintaining precise density control.
Solution Approach 2:
The patent uses parameter changes to automate the dummy pattern placement process. By defining density as a function of distance from feature patterns, the system automatically adjusts dummy pattern density without manual input. This parametric approach simplifies the design process while maintaining precise control over density distribution.
Data Source
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AI summary
Systems and methods for designing a dummy pattern layout for improving surface flatness of a wafer are provided. An exemplary system includes at least one processor and at least one memory storing instructions. The instructions, when executed by the at least one processor, cause the at least one processor to perform operations. The operations include identifying a feature pattern corresponding to a functional region of the wafer. The operations also include determining a property of the feature pattern based on a script associated with the feature pattern. The operations further include determining a dummy pattern rule based on the property of the feature pattern. Moreover, the operations include generating a dummy pattern corresponding to a vacant region of the wafer by wrap-filling dummy units in an adjacent area surrounding the feature pattern based on the dummy pattern rule.