Sacrificial Gate Segmentation for Reliable Alternative Metal Gate Formation
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Solution Overview
Problem
The existing semiconductor device fabrication processes face challenges in achieving reliable alternative gate electrode formation due to residual byproducts from sacrificial gate removal, which can hinder the complete removal of the second portion of the sacrificial gate structure, leading to defects and size variations in the alternative gate electrode, affecting threshold voltage and device performance.
Innovation Solution
A method involving a sacrificial gate structure with a first and second portion, where the first portion is removed using a dry etching process, followed by an oxidation process to form an oxide film on the second portion, allowing for its subsequent removal through a wet etching process, thereby preventing byproduct interference and ensuring accurate gate electrode formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional sacrificial gate removal process is used, then the gate electrode can be formed, but residual byproducts remain that hinder complete removal and cause defects
Solution Approach 1:
The sacrificial gate structure is divided into two portions: a first portion that is removed early in the process, and a second portion that remains temporarily to prevent harmful byproduct formation. This segmentation allows the second portion to be removed later without interfering with the gate electrode formation, ensuring both complete removal and high reliability.
Solution Approach 2:
The first portion of the sacrificial gate is removed in advance before gate electrode formation begins. This preliminary removal action prevents the generation of residual byproducts during the critical gate electrode formation process, while the second portion remains to continue providing structural support and preventing defects.
2Manufacturing precision
If the sacrificial gate structure is completely removed early, then no byproduct interference occurs, but the gate electrode size and position cannot be precisely controlled
Solution Approach 1:
The sacrificial gate is segmented into two functional portions: the first portion is removed early to eliminate byproduct interference, while the second portion remains temporarily to maintain precise gate electrode dimensions and positioning. The second portion is subsequently removed after serving its protective function.
Solution Approach 2:
The second portion of the sacrificial gate acts as an intermediary structure that temporarily fills the space where the gate electrode will be formed. It prevents harmful byproduct formation and ensures accurate gate sizing, then is removed to allow complete gate electrode formation without interference.
3Adaptability or versatility
If multiple etching and deposition steps are used, then the alternative metal gate process can be implemented, but the fabrication complexity increases
Solution Approach 1:
The fabrication process is segmented into distinct phases: first portion removal, gate electrode formation, second portion removal, and cap layer formation. This segmentation allows each step to be optimized independently, enabling alternative metal gate formation while managing overall process complexity through systematic organization.
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
This approach enhances the reliability of the alternative gate electrode forming process by ensuring complete removal of the sacrificial gate structure, preventing defects and maintaining intended gate size and threshold voltage, thus improving semiconductor device performance.
Implementation Method 1
forming an oxide film by oxidizing an upper surface of the second portion of the sacrificial gate structure
Implementation Method 2
The sacrificial gate removal process may include a dry etching process
Implementation Method 3
an oxidation process, and a wet etching process that are sequentially performed
Data Source
AI summary
Example methods for fabricating a semiconductor device and example semiconductor devices are disclosed. An example method may include forming a sacrificial gate structure on a substrate, and the sacrificial gate structure may include a first portion and a second portion. The method may further include, removing the first portion of the sacrificial gate structure and forming an oxide film by oxidizing an upper surface of the second portion of the sacrificial gate structure after removing the first portion of the sacrificial gate structure. The method may additionally include, forming a trench on the substrate by removing the oxide film and the second portion of the sacrificial gate structure; and forming a gate electrode that fills the trench.