Nitride-Lined STI Isolation Structures for Fin Spacing Reliability
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Solution Overview
Problem
As semiconductor devices continue to shrink in size, challenges arise in maintaining isolation between transistor components, leading to manufacturing defects and reduced electrical performance.
Innovation Solution
The formation of isolation structures, such as shallow trench isolation regions, is enhanced by using protective liners made of nitride layers that provide etch selectivity and reduce isolation loss during processing, along with a multi-layer structure that includes nitride and oxide layers to protect the isolation regions from subsequent etching and cleaning processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If minimum feature size is reduced to improve integration density, then more components can be integrated into a given area, but isolation between transistor components deteriorates leading to manufacturing defects and reduced electrical performance
Solution Approach 1:
The patent implements a multi-layer isolation structure where an inner shallow trench isolation region is nested within an outer shallow trench isolation region. This nested configuration allows the isolation structure to maintain effective separation between transistor components even as feature sizes are reduced, thereby preserving reliability while enabling higher integration density.
Solution Approach 2:
The patent employs composite materials by forming the inner isolation region with a first material and the outer isolation region with a second material. This composite approach enables differential etch selectivity and provides enhanced isolation performance, allowing the structure to maintain component separation at reduced feature sizes without compromising electrical performance.
2Ease of manufacture
If conventional single-layer isolation structures are used, then manufacturing process is simpler, but etching and cleaning processes cause isolation loss leading to manufacturing defects
Solution Approach 1:
The patent applies a protective liner material to the inner isolation region before subsequent etching and cleaning processes. This preliminary protective action prevents isolation loss during manufacturing, ensuring that the isolation structure maintains its integrity throughout the fabrication process without requiring complex process modifications.
Solution Approach 2:
The protective liner is nested within the outer isolation region, creating a protected inner isolation region. This nested configuration allows the manufacturing process to proceed with standard etching and cleaning steps while the protective liner prevents isolation loss, thereby improving manufacturing precision without significantly complicating the manufacturing process.
3Productivity
If feature sizes are reduced to increase integration density, then more components fit in a given area, but maintaining isolation between components becomes more difficult leading to electrical performance degradation
Solution Approach 1:
The nested dual-layer isolation structure provides enhanced isolation capability at reduced feature sizes. The inner isolation region nested within the outer isolation region creates multiple barriers that maintain component separation even when transistors are closely spaced, thereby preserving manufacturing precision and electrical performance while enabling higher integration density.
Solution Approach 2:
By using different materials for the inner and outer isolation regions, the patent creates a composite isolation structure with optimized properties. The first material in the inner region and the second material in the outer region provide differential etch selectivity and enhanced isolation, allowing precise maintenance of component isolation at reduced feature sizes.
Data Source
AI summary
A device, includes a first semiconductor fin and a second semiconductor fin; an isolation structure between the first semiconductor fin and the second semiconductor fin, the isolation structure comprising: an inner shallow trench isolation (STI) region; a first liner layer along sidewalls and a bottom surface of the inner STI region; and a STI hard mask on a top surface of the inner STI region. The STI hard mask and the first liner layer each comprise a higher concentration of nitrogen than the inner STI region.