Fin Isolation Profile Shaping to Prevent Source/Drain Merging
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Solution Overview
Problem
The increasing complexity of semiconductor manufacturing due to scaling down processes poses challenges in preventing the merging of source/drain regions in nanostructure channel FETs, such as GAA FETs, which can affect device performance and reliability.
Innovation Solution
An additional etch process is performed to modify the shape of isolation regions not covered by sacrificial gate structures, forming spacers that prevent the merging of adjacent source/drain regions by creating specific profiles in the isolation material, thereby protecting the well portions during subsequent fabrication stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If scaling down process is used to increase functional density, then production efficiency is improved and costs are lowered, but the complexity of processing and manufacturing increases
Solution Approach 1:
The patent performs an additional etch process to modify the shape of isolation regions before subsequent fabrication stages. This preliminary action creates specific profiles in the isolation material that prevent merging of source/drain regions in later processing steps, thereby addressing the complexity issue proactively while maintaining scaling benefits
2Productivity
If scaling down process is used to increase functional density, then production efficiency is improved and costs are lowered, but manufacturing precision becomes more difficult to maintain
Solution Approach 1:
The isolation region shape modification is performed in advance to create protective profiles before source/drain region formation. This preliminary action establishes precise geometric constraints that guide subsequent self-aligned processes, ensuring manufacturing precision is maintained despite scaling challenges
Solution Approach 2:
The modified isolation region acts as an intermediary structure that mediates between the fabrication process and the source/drain regions. By creating specific profiles with controlled overhangs or recesses, it serves as a protective template that ensures precise source/drain region formation without direct intervention in each subsequent step
3Reliability
If additional etch process is performed to modify isolation region shape, then reliability is improved by preventing source/drain merging, but device complexity increases
Solution Approach 1:
The additional etch process is performed as a preliminary step to establish protective isolation profiles before source/drain region formation. This single upfront modification prevents merging issues throughout subsequent processing, improving reliability while adding minimal process complexity compared to multiple corrective steps
Solution Approach 2:
The etch process modifies only specific local regions of the isolation material adjacent to well portions, creating targeted profiles with different characteristics in different areas. This local quality approach ensures source/drain separation where needed while maintaining standard processing elsewhere, balancing reliability improvement with process simplicity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The modified spacers effectively reduce the risk of source/drain region merging, enhancing the reliability and performance of nanostructure channel FETs by maintaining the integrity of the semiconductor device structure.
Implementation Method 1
an additional etch process is performed to modify the shape of the isolation region not covered by the sacrificial gate structures
Data Source
AI summary
Methods for forming a semiconductor device structure are described. The method includes forming a fin structure from a substrate, depositing an insulating material around the fin structure, recessing the insulating material, and forming a sacrificial gate structure over a first portion of the fin structure. A first portion of the insulating material is covered by the sacrificial gate structure, and a second portion of the insulating material is exposed. The method further includes modifying a top surface of the exposed second portion of the insulating material, and the modified top surface has a profile different from a top surface of the first portion of the insulating material. After the modifying of the top surface, the method further includes depositing a first spacer on the sacrificial gate structure a second portion of the fin structure and recessing the second portion of the fin structure.