Carbide Layer Protects Semiconductor Back-Channel from Plasma Damage
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Solution Overview
Problem
Existing thin film transistors, particularly in liquid crystal display devices, face issues with off-current variations and deterioration due to plasma damage and contamination of the back-channel portion during manufacturing, which cannot be adequately stabilized by surface treatments alone.
Innovation Solution
A chemically and thermally stable carbide layer is formed over and in contact with the semiconductor layer to act as a protective layer, preventing atoms that cause semiconductor characteristic changes from contacting or entering the semiconductor layer, and is designed to withstand chemical and thermal exposure during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface treatment (plasma discharge) is applied to the back-channel portion to remove impurities, then off current is reduced, but the semiconductor characteristics cannot be sufficiently stabilized due to lack of chemical and thermal stability
Solution Approach 1:
A carbide layer is introduced as an intermediary protective layer between the semiconductor layer and the external environment. This carbide layer serves as a mediator that prevents harmful factors (plasma, moisture, impurities) from directly contacting the semiconductor layer, while also providing chemical and thermal stability that surface treatment alone cannot achieve.
Solution Approach 2:
The invention uses a composite structure combining the semiconductor layer with a carbide layer. This composite material approach leverages the beneficial properties of both materials: the semiconductor properties of the base layer and the protective, chemically stable properties of the carbide layer, creating a structure that is both functional and protected.
2Object-affected harmful factors
If a protection film (silicon oxide or silicon nitride) is formed on the back-channel side, then the semiconductor layer is protected, but the easily damaged semiconductor film is adversely affected by plasma
Solution Approach 1:
The invention changes the material parameter of the protective layer from conventional silicon oxide or silicon nitride to carbide material. This parameter change provides different protective characteristics that are compatible with plasma processing, offering both protection and plasma resistance simultaneously.
Solution Approach 2:
The carbide layer acts as an intermediary that is compatible with both the semiconductor layer and the plasma processing environment. Unlike conventional protection films that are damaged by plasma, the carbide intermediary withstands plasma exposure while still protecting the underlying semiconductor layer.
3Ease of manufacture
If the back-channel portion is exposed to work environment during manufacturing, then manufacturing processes can be completed, but plasma damage and impurity adhesion cause deterioration of thin film transistor
Solution Approach 1:
The carbide layer is formed in advance before the semiconductor layer is exposed to the work environment during manufacturing. This preliminary protective action ensures that when plasma processing and other manufacturing steps are performed, the semiconductor layer is already protected, preventing subsequent damage and impurity adhesion.
Solution Approach 2:
The carbide layer provides beforehand cushioning protection against the harmful effects of the work environment. It acts as a pre-established protective barrier that cushions the semiconductor layer from plasma damage, moisture, and impurities that would otherwise cause deterioration during manufacturing.
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 carbide layer effectively suppresses changes in semiconductor characteristics, improves reliability, and reduces leakage current by acting as a dense, chemically stable protective film at the interface between the semiconductor and carbide layers, even when exposed to various chemical solutions or heated during processing.
Implementation Method 1
The carbide layer serves as a protective layer which prevents atoms or the like that causes change in semiconductor characteristics from being in contact with or entering the semiconductor layer
Implementation Method 2
deterioration, change in qualities or the like of the carbide layer can be suppressed even when the carbide layer is exposed to various chemical solutions or the like in the manufacturing process because the carbide layer is a chemically stable film
Implementation Method 3
the carbide layer is also a thermally stable film; thus, at the interface between the semiconductor layer and the carbide layer, change in semiconductor characteristics can be suppressed when the carbide layer is heated
Data Source
AI summary
An object is to prevent contamination of a semiconductor film in a transistor or a semiconductor device including the transistor. Another object is to suppress variation in electrical characteristics and deterioration. A transistor including: a gate electrode layer provided over a substrate; a gate insulating film provided over the gate electrode layer; a semiconductor layer which is provided over the gate insulating film and which overlaps the gate electrode layer; a carbide layer provided over and in contact with a surface of the semiconductor layer; and a source electrode layer and a drain electrode layer which are electrically connected to the semiconductor layer is provided.