Copper Electrode Oxidation Prevention via Nitrogen Plasma
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Solution Overview
Problem
Conventional semiconductor devices for thin-film transistors (TFTs) face complications in the fabrication process due to the need for additional alloy layers to prevent copper oxidation, leading to increased process complexity, line resistance, and insulation failures.
Innovation Solution
A method involving the formation of a thin-film semiconductor substrate by irradiating electrodes and lines with nitrogen plasma and exposing them to silane gas before forming an insulating oxide layer, simplifying the process and reducing oxidation and resistance issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an alloy layer including a chemical element with oxidation-reduction potential greater than copper is disposed between a copper line and an insulating barrier film, then oxidation of the copper line is prevented, but the fabricating process becomes complicated and line resistance increases
Solution Approach 1:
The patent removes the alloy layer from the conventional structure, extracting only the essential function of oxidation prevention. By using a simple copper line without an additional alloy layer, the fabricating process is simplified while oxidation protection is achieved through the plasma treatment method that creates a protective surface state on the copper itself.
Solution Approach 2:
The patent introduces nitrogen plasma as an intermediary treatment between the copper line formation and the insulating barrier film deposition. This plasma treatment creates a modified surface state on the copper that prevents oxidation without requiring an additional material layer, thus simplifying the overall structure while maintaining reliability.
2Reliability
If an alloy layer is disposed between a copper line and an insulating barrier film, then oxidation is prevented, but line resistance increases
Solution Approach 1:
The patent extracts the alloy layer that causes resistance increase while maintaining oxidation prevention through plasma treatment. The copper line remains pure copper without additional resistive layers, achieving both low resistance and oxidation protection.
Solution Approach 2:
The patent replaces the material-based oxidation prevention (alloy layer) with a process-based solution (nitrogen plasma treatment). This substitution eliminates the need for additional materials that would increase resistance, using instead a surface modification process that preserves the copper's electrical properties.
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 decreases oxidation and resistance of electrodes and lines, reduces insulation failures, and simplifies the fabrication process, enhancing the reliability of TFTs in display devices.
Implementation Method 1
irradiating the at least one of the electrode and the line with nitrogen plasma after the forming of the at least one of the electrode and the line
Implementation Method 2
exposing surfaces of a top and an end portion of the at least one of the electrode and the line with silane (SiH4) gas after the irradiating
Data Source
AI summary
A method of fabricating a thin-film transistor substrate including a thin-film semiconductor includes: forming a metal film mainly comprising Cu above a substrate; forming a source electrode and a drain electrode by processing the metal film in a predetermined shape; irradiating the source electrode and the drain electrode with nitrogen plasma; exposing surfaces of a top and an end portion of the source electrode and the drain electrode with silane (SiH4) gas; and forming an insulating layer comprising an oxide on the source electrode and the drain electrode.