Dummy Active Region Layout for Uniform MOSFET Sidewall Angles
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Solution Overview
Problem
The miniaturization of semiconductor devices leads to variations in active region spacing, causing differences in sidewall angles and dopant concentration, which affect the performance of transistors, particularly metal-oxide-semiconductor field-effect transistors (MOSFETs), and existing dummy patterns struggle to achieve loading uniformity.
Innovation Solution
Incorporating dummy active regions adjacent to the periphery of active regions to improve pattern density during the etching process, reducing sidewall angle variations and enhancing transistor performance by reducing the difference in etching mask pattern density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device dimensions are scaled down to increase device density, then productivity and performance are improved, but manufacturing precision deteriorates due to variations in active region spacing affecting sidewall angles and dopant concentration
Solution Approach 1:
The patent introduces dummy active regions as intermediary structures between real active regions. These dummy regions serve as mediators that absorb etching process variations and prevent them from affecting the real active regions. The dummy active regions are positioned in spaces between active regions and have the same structural characteristics (sidewalls, doping) as the real active regions, thereby creating a buffer zone that stabilizes the etching environment and ensures uniform sidewall angles across all active regions regardless of spacing variations.
2Manufacturing precision
If dummy patterns are added to improve loading uniformity, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by making the dummy active regions identical in structure to the real active regions (same sidewalls, same doping concentration, same gate structure) but positioning them only in specific locations where spacing variations occur. This localized application of dummy structures provides the necessary loading uniformity exactly where needed, rather than uniformly across the entire device, thereby minimizing the increase in overall device complexity while achieving the desired manufacturing precision improvement.
3Adaptability or versatility
If active region spacing varies based on design requirements, then adaptability is improved, but manufacturing precision deteriorates due to etching loading effects causing different sidewall angles
Solution Approach 1:
The dummy active regions act as intermediaries that decouple the relationship between varying active region spacing and sidewall angle formation. By placing dummy regions in the spaces between active regions, they create a consistent etching environment that maintains uniform sidewall angles even when the actual spacing between functional active regions varies according to design requirements. This allows designers to freely adjust active region spacing for circuit optimization without compromising manufacturing precision.
Data Source
AI summary
A semiconductor structure includes a first active region, a first dummy active region and a second dummy active region, and a first gate structure extending over the first active region in a first direction. The first active region has a first edge extending in the first direction, and a second edge connected to the first edge and extending in a second direction. The first dummy active region has a first edge extending in the first direction and immediately adjacent to the first edge of the first active region. The second dummy active region has a first edge extending in the second direction and immediately adjacent to the second edge of the first active region.