Fin-Shaped Active Region Layout to Prevent Isolation-Induced Cracking
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Solution Overview
Problem
Existing methods for forming multi-gate devices like FinFETs and GAA transistors face issues with fin cracking due to variations in isolation feature configurations, leading to device failure.
Innovation Solution
The formation of fin-shaped active regions with uniform and non-uniform sidewall profiles, using a patterned photoresist and mandrel layer to reduce stress and minimize cracking by ensuring consistent isolation feature formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If isolation features are formed using existing methods, then device isolation is achieved, but fin cracking occurs due to variations in isolation feature configurations
Solution Approach 1:
The patent applies parameter changes by modifying the mandrel width parameter to be non-uniform (wider at ends, narrower in middle) which directly changes the isolation feature configuration. This parameter modification ensures uniform isolation features on both sides of the fin, eliminating the variations that cause fin cracking while maintaining proper device isolation.
Solution Approach 2:
The patent uses asymmetry by intentionally designing the mandrel with non-uniform width along its length (wider at the first and second ends, narrower in the middle). This asymmetric mandrel configuration compensates for edge effects and process variations, ensuring that the isolation features formed at opposite sides of the fin are uniform, thereby preventing fin cracking.
2Productivity
If aggressive scaling down of IC dimensions is performed, then production efficiency increases and costs decrease, but fin cracking issues arise due to variations between isolation features
Solution Approach 1:
The patent modifies the mandrel width parameter to create a non-uniform profile (wider at ends, narrower in middle). This parameter change ensures that even during aggressive scaling, the isolation features formed at opposite sides of the fin remain uniform, preventing fin cracking while maintaining the benefits of scaled-down dimensions and high production efficiency.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the mandrel with a specific non-uniform width profile before isolation feature formation. This preliminary mandrel design anticipates and compensates for process variations that would otherwise cause isolation feature mismatches and fin cracking, ensuring reliability even at scaled dimensions.
3Reliability
If multi-gate devices are formed with elevated temperature processes, then gate control is improved, but variations between isolation features lead to fin cracking
Solution Approach 1:
The patent uses asymmetric mandrel design (non-uniform width along length) to compensate for thermal expansion and stress variations that occur during elevated temperature processing. This asymmetric configuration ensures that isolation features formed at opposite sides of the fin remain uniform even after high-temperature processes, preventing fin cracking while maintaining improved gate control.
Solution Approach 2:
The patent changes the mandrel width parameter from uniform to non-uniform (wider at ends, narrower in middle) to account for thermal effects during elevated temperature processing. This parameter modification ensures that thermal expansion and stress distribution result in uniform isolation features on both sides of the fin, eliminating fin cracking while preserving gate control improvements.
Data Source
AI summary
A method includes forming a fin-shaped active region protruding from a substrate and having a uniform width, wherein, when viewed from top, the fin-shaped active region comprises a first segment having substantially straight sidewalls and a second segment immediately adjacent to the first segment and having curved sidewalls; forming a gate structure over the second segment of the fin-shaped active region; replacing the first segment of the fin-shaped active region with an isolation structure; and forming source/drain features coupled to the second segment of the fin-shaped active region.