Semiconductor Metal Gate Silicide Formation
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Solution Overview
Problem
The existing metal gate electrode structures in semiconductor devices face issues with increased resistance due to oxidation of the metal film surface and high interfacial resistance between the silicon and metal films, leading to reduced switching speed of transistors.
Innovation Solution
A method is developed to form a metal-silicon compound film on a metal film without exposing the semiconductor substrate to the atmosphere, followed by depositing a silicon film and etching the metal and compound films to create a laminated structure with a low interfacial resistance, preventing oxidation and void formation, and using a silicide layer to reduce stress on the gate insulating film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the metal film surface is exposed to atmosphere during fabrication, then the metal film can be formed and processed, but the metal film surface oxidizes and resistance increases
Solution Approach 1:
A silicide layer is introduced as an intermediary between the metal film and the silicon film. This silicide layer prevents direct contact between the metal film surface and oxidizing environment, while also providing good electrical contact properties. The silicide layer acts as a protective mediator that eliminates oxidation issues without compromising the metal-silicon interface electrical characteristics.
Solution Approach 2:
The fabrication process utilizes an inert atmosphere (vacuum or inert gas environment) during the formation of the silicide layer and subsequent processing steps. This inert environment prevents oxidation of the metal film surface while allowing the necessary thermal processing to occur, thereby maintaining low resistance at the gate electrode interface.
2Manufacturing precision
If a silicide layer is formed by reacting metal film and silicon film, then selective silicide formation occurs at the interface, but the metal film surface oxidizes and desired interfacial resistance is not obtained
Solution Approach 1:
The silicide layer is formed preliminarily on the metal film surface before the metal film is contacted with the silicon film. This preliminary silicide formation protects the metal film from oxidation during subsequent processing steps. The silicide layer is then selectively removed from areas where metal-silicon contact is desired, achieving both protection during fabrication and proper electrical contact at the interface.
Solution Approach 2:
Instead of forming silicide by reacting metal and silicon together, the approach is inverted: silicide is first formed on the metal film surface, then the silicon film is added. This inversion allows the metal film to be protected by the silicide layer during fabrication, while still achieving the desired metal-silicon interface for electrical contact through selective removal of excess silicide.
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 significantly improves the switching speed of transistors by maintaining low interfacial resistance and reducing stress on the gate insulating film, enhancing the reliability of the semiconductor device.
Implementation Method 1
a structure wherein a silicide layer is formed at the interface between a silicon film and a metal film wherein the metal film and the silicon film are caused to react with each other to form the silicide layer
Implementation Method 2
the surface of the metal film is oxidized so that the resistance of the gate electrode is increased
Data Source
AI summary
An aspect of the present disclosure, there is provided a method for fabricating a semiconductor device, including, forming a gate insulating film on a semiconductor substrate, forming a metal film on the gate insulating film, depositing a metal-silicon compound film on the metal film without exposing the semiconductor substrate into atmosphere after forming the metal film, forming a silicon film on the metal-silicon compound film, and etching the metal film, the metal-silicon compound film, and the silicon film.