Composite Oxide Layer Structure for Fin Damage Protection
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Solution Overview
Problem
The fabrication process of semiconductor devices often damages underlying insulating layers, leading to issues such as charge leakage and device failures, which negatively impact reliability and performance.
Innovation Solution
A method involving the use of two separate oxide layers, where a first oxide layer is formed adjacent a fin and a dummy gate is subsequently removed, followed by the formation of a second oxide layer to cover any damage inflicted on the first oxide layer during the dummy gate removal process, forming a composite oxide layer for improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single oxide layer is formed adjacent a fin before dummy gate removal, then the fabrication process can be completed with standard steps, but the oxide layer is damaged during dummy gate removal leading to charge leakage and device failures
Solution Approach 1:
The single oxide layer is divided into two separate oxide layers: a first oxide layer formed before dummy gate removal and a second oxide layer formed after dummy gate removal. The first oxide layer serves as a sacrificial layer that protects the fin during initial processing, while the second oxide layer provides the final protective barrier. This segmentation allows each layer to fulfill specific functions without compromising the other, resolving the contradiction between manufacturing simplicity and device reliability.
Solution Approach 2:
The first oxide layer is formed in advance before the dummy gate removal process. This preliminary oxide layer is specifically designed to withstand the dummy gate removal process, protecting the fin structure during this critical fabrication step. After the dummy gate is removed, the second oxide layer is then formed to provide long-term protection. This preliminary action ensures that the fin is protected during the potentially damaging dummy gate removal process while maintaining overall process simplicity.
2Loss of time
If the dummy gate is removed using conventional processes, then the fabrication timeline is maintained, but underlying insulating layers are damaged causing charge leakage
Solution Approach 1:
The first oxide layer is formed beforehand as a protective cushion layer specifically to absorb and mitigate the damage caused during dummy gate removal. This sacrificial oxide layer is designed to be present during the dummy gate removal process, protecting the underlying fin and insulating structures from etching damage. After serving its protective function, the first oxide layer can be selectively removed or covered by the second oxide layer, while the fabrication timeline remains maintained.
3Productivity
If no additional oxide layer is formed after dummy gate removal, then the fabrication process is shorter, but device reliability deteriorates due to exposed damaged layers
Solution Approach 1:
The protective oxide structure is segmented into two distinct layers formed at different stages of the fabrication process. The first oxide layer is formed before dummy gate removal to provide initial protection, while the second oxide layer is formed after dummy gate removal to provide final protection and ensure long-term device reliability. This segmentation allows each layer to be optimized for its specific temporal and functional requirements without significantly extending the overall fabrication process.
Data Source
AI summary
1. A semiconductor structure includes a first fin; an isolation structure adjacent the first fin; a dielectric layer adjacent the isolation structure; a first oxide layer adjacent the first fin, the isolation structure, and the dielectric layer, and a second oxide layer adjacent the first oxide layer. The first oxide layer and the second oxide layer define a composite oxide layer. A horizontal portion of the composite oxide layer is thicker than a vertical portion of the composite oxide layer.