Multigate Cladding Structure for Footing-Free GAA Gate Fabrication
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Solution Overview
Problem
Existing gate-all-around (GAA) devices face challenges in fabricating a gate structure that leads to footing issues and diffusion into channels, degrading device performance and increasing processing complexity.
Innovation Solution
A method for fabricating multigate devices with an engineered cladding layer that includes forming a diffusion blocking layer before the cladding layer, using rapid thermal nitridation to convert a liner into silicon nitride, and selectively growing the cladding layer on semiconductor surfaces to prevent diffusion and eliminate footing issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a cladding layer is formed around an active region in conventional GAA devices, then the gate structure can be fabricated, but footing issues occur that cause residual defects during gate replacement
Solution Approach 1:
A liner layer is formed on the active region before the cladding layer is deposited. This preliminary liner layer prevents direct contact between the cladding layer and the active region, eliminating footing issues and residual defects during gate replacement while enabling successful gate structure fabrication
2Ease of manufacture
If a cladding layer is formed around an active region, then the gate structure can be fabricated, but diffusion into channels occurs that reduces carrier mobility and degrades device performance
Solution Approach 1:
A liner layer is introduced as an intermediary between the active region and the cladding layer. This liner layer acts as a diffusion barrier that prevents harmful diffusion into the channel while allowing the cladding layer to be formed for gate structure fabrication, thereby maintaining device performance
3Productivity
If IC dimensions are reduced to improve production efficiency and lower costs, then manufacturing productivity increases, but manufacturing process complexity increases
Solution Approach 1:
The cladding structure is segmented into multiple functional layers: a liner layer for protection and diffusion prevention, and a cladding layer for gate formation. This segmentation allows each layer to perform its specific function optimally, enabling continued scaling without proportionally increasing process complexity
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 engineered cladding layer enhances device performance by reducing diffusion and footing defects, improving gate control and processing efficiency in GAA devices.
Implementation Method 1
using rapid thermal nitridation to convert a liner into silicon nitride
Implementation Method 2
using rapid thermal nitridation to convert a liner into silicon nitride
Implementation Method 3
selectively growing the cladding layer on semiconductor surfaces
Data Source
AI summary
The present disclosure provides a method of making a semiconductor device. The method includes forming a semiconductor stack on a substrate, wherein the semiconductor stack includes first semiconductor layers of a first semiconductor material and second semiconductor layers of a second semiconductor material alternatively stacked on the substrate; patterning the semiconductor stack and the substrate to form a trench and an active region being adjacent the trench; epitaxially growing a liner of the first semiconductor material on sidewalls of the trench and sidewalls of the active region; forming an isolation feature in the trench; performing a rapid thermal nitridation process, thereby converting the liner into a silicon nitride layer; and forming a cladding layer of the second semiconductor material over the silicon nitride layer.