Nanosheet Transistor Corner Spacers for Sub-FIN Leakage Suppression
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Solution Overview
Problem
Existing nanosheet transistor structures face challenges in suppressing sub-FIN leakage while maintaining channel strain, leading to performance losses at the bottom of the device.
Innovation Solution
The introduction of bottom corner spacers under the lowest channel region, on both the source and drain sides of the device, in conjunction with inner sidewall spacers and gate structures, helps to suppress sub-FIN leakage and maintain channel strain through epitaxial regrowing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional nanosheet transistor structures are used, then device density and performance are improved, but sub-FIN leakage increases and channel strain is lost at the bottom of the device
Solution Approach 1:
The device is segmented into multiple functional regions by introducing corner spacers that divide the bottom region into distinct source and drain sides. This segmentation allows independent control of leakage suppression and strain maintenance in different areas, resolving the contradiction between overall performance improvement and localized leakage issues
Solution Approach 2:
Corner spacers are strategically placed only at the bottom corners of the nanosheet structure, providing localized leakage suppression and strain maintenance exactly where needed. This local quality approach allows the majority of the device to maintain high performance while addressing specific harmful effects at critical locations
2Productivity
If conventional nanosheet transistor structures are used, then device density is improved, but channel strain is lost at the bottom of the device
Solution Approach 1:
Corner spacers are formed in advance before epitaxial regrowth, creating a protective structure that maintains channel strain during subsequent processing. This preliminary action prevents strain loss before it can occur during device fabrication
Solution Approach 2:
Corner spacers act as intermediary structures that mediate between the nanosheet channel and the surrounding environment. They serve as a physical barrier that preserves channel strain while allowing the device to achieve high density through conventional fabrication processes
Data Source
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AI summary
The present disclosure relates to semiconductor structures and, more particularly, to nanosheet transistor structures and methods of manufacture. The structure includes: a plurality of stacked semiconductor nanosheets over a semiconductor substrate; a plurality of gate structures surrounding individual nanosheets of the plurality of semiconductor nanosheets; an inner sidewall spacer adjacent each of the plurality of gate structures; and corner spacers under the plurality of stacked semiconductor nanosheets.