Flexible Dummy Cell Arrangement for Pattern Density Uniformity
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Solution Overview
Problem
Current methods for adding dummy features in semiconductor fabrication face challenges with limited degree of freedom and effectiveness in tuning pattern density, leading to issues like dishing, erosion, and incomplete filling, especially in smaller feature sizes and irregular shapes, which affect imaging resolution and increase costs.
Innovation Solution
A flexible dummy cell arrangement that includes unit dummy cells with a base unit and fixed units, and flexible extended dummy cells that can fill irregular regions without strict layout constraints, allowing for more efficient filling of remaining spaces and improved pattern uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If regular dummy cells are used for filling, then the dummy region can be filled with standard patterns, but large dummy areas remain near area boundaries and pattern density uniformity is poor
Solution Approach 1:
The dummy cell is divided into modular components (active region, interconnect region, shared regions) that can be independently configured. This segmentation allows the dummy cell to be adapted to different positions and boundary conditions within the dummy region, enabling complete filling without large empty areas while maintaining pattern density uniformity.
Solution Approach 2:
The dummy cell design incorporates flexible configurations where certain regions can be selectively activated or deactivated based on position within the dummy region. This dynamic adaptability allows the same dummy cell structure to effectively fill various spaces including irregular boundaries, eliminating remaining empty areas while maintaining consistent pattern density throughout.
2Reliability
If dummy features are added to enhance CMP performance, then dishing and erosion effects are reduced, but the degree of freedom and effectiveness to tune pattern density is limited
Solution Approach 1:
Different regions of the dummy cell are designed with specific functions: active regions for pattern density control, interconnect regions for electrical connectivity, and shared regions for boundary flexibility. This local differentiation allows selective tuning of pattern density in different areas while maintaining overall CMP performance through the complete dummy cell structure.
Solution Approach 2:
The dummy cell structure serves multiple functions simultaneously: it provides CMP enhancement through its overall presence, enables pattern density tuning through configurable active regions, and offers adaptability to different boundary conditions through shared regions. This multi-functionality resolves the contradiction between CMP performance and pattern density tuning flexibility.
3Manufacturing precision
If complete dummy cell filling is achieved, then spatial charging effect and micro-loading effect are reduced, but the complexity of simulations and calculations increases
Solution Approach 1:
The dummy cell design uses repetitive modular units that can be copied and arranged in systematic patterns. This regularity simplifies simulations and calculations compared to irregular dummy feature placements, as the repeating structure allows for more efficient computational modeling while still achieving complete filling and reduced spatial charging and micro-loading effects.
Data Source
AI summary
A dummy cell arrangement in a semiconductor device includes a substrate with a dummy region, unit dummy cells arranged in rows and columns in the dummy region, and flexible extended dummy cells arranged in rows and columns filling up remaining dummy region. The unit dummy cell includes exactly one base dummy cell and exactly two fixed dummy cells at opposite sides of the base dummy cell in row direction or in column direction and the flexible extended dummy cell includes at least two base dummy units and a plurality of flexible dummy units at two opposite sides of the two base dummy units in row direction or in column direction. The base dummy cell consists of at least one fin, at least one gate and at least one contact, while the flexible dummy cell consists of one gate and one contact without any fin.