Nanosheet Transistor Corner Spacers for Sub-FIN Leakage Control
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Solution Overview
Problem
Conventional 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 combination with inner sidewall spacers and gate structures, helps to suppress sub-FIN leakage and maintain channel strain through epitaxial regrowing of source and drain regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional nanosheet transistor structures are used, then device density and performance are improved, but sub-FIN leakage occurs and channel strain is lost at the bottom of the device
Solution Approach 1:
The device is segmented into distinct functional regions through the introduction of corner spacers that divide the bottom region into separate source and drain segments. This segmentation prevents leakage paths while maintaining the integrity of the channel strain, resolving the contradiction between device performance and sub-FIN leakage suppression.
Solution Approach 2:
Corner spacers act as intermediary structures positioned at the bottom corners of the nanosheet transistor. These spacers mediate between the source and drain regions, blocking leakage currents while preserving the mechanical strain in the channel. The intermediary structures enable both high device performance and leakage suppression simultaneously.
2Productivity
If conventional nanosheet transistor structures are used, then device density is increased, but channel strain is lost at the bottom of the device
Solution Approach 1:
The corner spacers segment the bottom region to create distinct strain-preserved zones. By dividing the structure into controlled segments, the strain is maintained in the channel region while the spacer regions provide structural support and prevent strain relaxation, thus maintaining productivity while preserving strength.
Solution Approach 2:
Different regions of the device are given different local qualities: the channel region maintains high strain for carrier mobility, while the corner spacer regions provide structural stability. This local differentiation allows the device to achieve high density with preserved channel strain, resolving the contradiction between productivity and strength.
Data Source
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.