Oxidation Layer Barrier for Gate Last Process Etching
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Solution Overview
Problem
When replacing a polysilicon gate electrode with a metal gate electrode in semiconductor devices, the etchant used to remove polysilicon can penetrate through weak points in the sidewall of the gate structure, damaging underlying features like source and drain regions, which is a challenge in achieving desired device performance.
Innovation Solution
A method involving the formation of an oxidation layer over the channel region and sidewalls of the fin structure, which acts as a barrier to prevent etchant penetration during the removal of the dummy gate, thereby protecting the underlying source and drain regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a high amount of etchant is applied to remove the polysilicon gate electrode, then the polysilicon removal is complete, but the etchant penetrates through weak points of the sidewall and damages the underlying source and drain regions
Solution Approach 1:
An oxidation layer is introduced as an intermediary barrier between the etchant and the source/drain regions. This oxidation layer forms on the sidewalls of the gate structure and prevents etchant penetration, thereby protecting the underlying features while allowing complete polysilicon removal
Solution Approach 2:
The oxidation layer is formed in advance before the etching process. This preliminary oxidation creates a protective barrier that prevents etchant damage to source and drain regions during the subsequent polysilicon removal step
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 oxidation layer effectively prevents damage to the source and drain regions, ensuring the integrity of the semiconductor device during the transition from a polysilicon to a metal gate electrode, enhancing device performance and reliability.
Implementation Method 1
forming an oxidation layer that covers a portion of the channel region and the sidewalls of the fin structure
Data Source
AI summary
Embodiments of the present disclosure relate generally to a semiconductor device and method of fabricating the same, the semiconductor device includes a semiconductor substrate and a gate stack disposed over a channel region of the semiconductor device, the gate stack includes an oxidation layer, a gate dielectric and a gate electrode, the oxidation layer at least covers a portion of the channel region of the semiconductor device and may act as a barrier to prevent damage to the underlying features, such as the source and drain regions, during removal of a dummy gate in a gate last process.