Semiconductor Electrode Protective Layers for Contact Resistance
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Solution Overview
Problem
In the manufacturing of thin film transistors, high contact resistance at the interface between semiconductor layers and electrode layers leads to signal delay and display unevenness, particularly in large-area display devices, due to factors like dust or impurity contamination on the electrode surfaces.
Innovation Solution
A semiconductor device design where source and drain electrode layers are in contact with a channel formation region through protective layers formed from a second semiconductor material, which prevents the formation of high-resistance films and ensures uniform conductivity, reducing parasitic resistance and enhancing field effect mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrode layers are directly contacted with semiconductor layers, then manufacturing process is simple, but contact resistance increases due to dust or impurity contamination
Solution Approach 1:
An insulating film is introduced as an intermediary layer between the electrode layer and the semiconductor layer. This insulating film prevents direct contact that would allow dust or impurity contamination, thereby reducing contact resistance while maintaining a relatively simple manufacturing process. The insulating film acts as a barrier that mediates the interface between the two functional layers.
Solution Approach 2:
The insulating film is formed on the electrode layer before the semiconductor layer is deposited. This preliminary action of creating the insulating barrier prior to semiconductor layer formation prevents contamination from occurring during subsequent manufacturing steps, thereby ensuring low contact resistance from the outset.
2Reliability
If insulating film is added between electrode and semiconductor layers, then contact resistance is reduced, but device complexity increases
Solution Approach 1:
The insulating film is applied locally only at the interface between the electrode layer and the semiconductor layer, rather than throughout the entire device structure. This localized approach reduces contact resistance at the critical interface while minimizing the increase in overall device complexity. The insulating film is confined to where it is most needed for electrical performance.
3Speed
If high conductivity material is used for electrode layers, then signal delay is reduced, but parasitic resistance variations occur due to surface contamination
Solution Approach 1:
The insulating film serves as a protective intermediary between the high conductivity electrode layer and the environment, preventing dust or impurity contamination that would cause parasitic resistance variations. This allows the electrode layer to maintain its high conductivity for fast signal transmission while the insulating film ensures uniform electrical characteristics by blocking contamination pathways.
Solution Approach 2:
The insulating film is formed on the electrode layer before subsequent manufacturing steps, preliminarily protecting the high conductivity material from surface contamination. This preliminary protective action ensures that the electrode layer maintains uniform electrical characteristics throughout the manufacturing process and device operation.
Data Source
AI summary
One of factors that increase the contact resistance at the interface between a first semiconductor layer where a channel is formed and source and drain electrode layers is a film with high electric resistance formed by dust or impurity contamination of a surface of a metal material serving as the source and drain electrode layers. As a solution, a first protective layer and a second protective layer including a second semiconductor having a conductivity that is less than or equal to that of the first semiconductor layer is stacked successively over source and drain electrode layers without exposed to air, the stack of films is used for the source and drain electrode layers.