Variable-Sized Active Regions With Dummy Gates for Dense Cell Layouts
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Solution Overview
Problem
Current semiconductor manufacturing processes face challenges in maximizing transistor density within a given area while maintaining design rule compliance and efficient current leakage management.
Innovation Solution
The introduction of isolation dummy gates that divide active regions within a cell region, allowing for non-full projection of active regions and varying their size and spacing to increase transistor density without sacrificing performance or exceeding design rule constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If active regions are made larger to increase transistor density, then transistor density improves, but current leakage increases
Solution Approach 1:
The patent divides active regions into multiple smaller sub-regions separated by isolation dummy gates. This segmentation allows the total active region area to be maintained for high transistor density while breaking up continuous large active regions into smaller isolated segments, thereby reducing current leakage paths between adjacent transistors.
Solution Approach 2:
Isolation dummy gates are introduced as intermediary structures between adjacent active regions. These dummy gates act as barriers that prevent direct current leakage between neighboring transistors while allowing the active regions to maintain their functional spacing and electrical connectivity through the gate structure.
2Productivity
If transistors are placed closer together to increase density, then transistor density improves, but design rule compliance becomes difficult
Solution Approach 1:
The patent uses dummy gates that are identical in structure and material composition to functional gates, allowing them to be placed in the same manufacturing layers without requiring additional process steps. This copying approach enables close transistor spacing while maintaining design rule compliance, as the dummy gates are treated as regular gate structures by the manufacturing process.
Solution Approach 2:
The isolation dummy gates serve multiple functions: they act as electrical isolation barriers between active regions, maintain design rule spacing requirements, and can be integrated into the same gate manufacturing process as functional gates. This multi-functionality allows them to address both density and compliance requirements simultaneously.
3Object-generated harmful factors
If isolation structures are added to reduce current leakage, then current leakage control improves, but cell area efficiency decreases
Solution Approach 1:
The patent combines the isolation function with the gate structure itself by using dummy gates that are formed in the same layers and process steps as functional gates. This merging eliminates the need for separate isolation structures, as the dummy gates perform both the gate function (when connected) and the isolation function (when disconnected), thereby improving cell area efficiency.
Solution Approach 2:
The patent optimizes the dimensions and spacing of dummy gates to achieve effective current leakage blocking with minimal area overhead. By carefully controlling the width, length, and spacing parameters of the dummy gates, the design achieves adequate isolation performance while minimizing the area consumed by isolation structures.
Data Source
AI summary
A semiconductor device includes a substrate; and a cell region having opposite first and second sides, the cell region including active regions formed in the substrate; relative to an imaginary first reference line, a first majority of the active regions having first ends which align with the first reference line, the first side being parallel and proximal to the first reference line; relative to an imaginary second reference line in the second direction, a second majority of the active regions having second ends which align with the second reference line, the second side being parallel and proximal to the second reference line; and gate structures correspondingly on first and second ones of the active regions; and relative to the second direction, a first end of a selected one of the gate structures abuts an intervening region between the first and second active regions.