Thin-Film Transistor Barrier Layer Density for Copper Diffusion Control
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Solution Overview
Problem
Conventional thin-film transistor barrier layers fail to provide sufficient barrier properties when thinned, leading to copper diffusion into semiconductor layers, which affects the performance and reliability of organic electroluminescence display devices.
Innovation Solution
A thin-film transistor with a barrier layer composed of nitrogen and molybdenum, having a density between 7.5 and 10.5 g/cm3, is implemented, which includes a molybdenum nitride film with a thickness of at least 2 nm and no more than 30 nm, and a contact layer between the semiconductor and barrier layers, formed using sputtering with nitrogen and argon gases to prevent copper diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the barrier layer is thinned to enable low-cost and workable wet etching processes, then ease of manufacture is improved, but barrier properties deteriorate leading to copper diffusion into the semiconductor layer
Solution Approach 1:
The patent changes the density parameter of the barrier layer from conventional values to a specific range of 7.5 g/cm³ to 10.5 g/cm³. This parameter change enables the barrier layer to maintain sufficient copper diffusion blocking capability even when thinned to 3 nm to 10 nm thickness, thereby achieving both ease of wet etching and reliable barrier properties simultaneously
Solution Approach 2:
The patent employs a composite barrier layer structure consisting of a molybdenum nitride film combined with a nitrogen-containing film. This composite material approach creates a barrier layer with optimized density and composition that provides superior copper diffusion resistance while maintaining thin thickness for easy etching processes
2Power
If copper is used as source electrode and drain electrode material to reduce line resistance, then electrical conductivity is improved, but thermal diffusion of copper into the semiconductor layer occurs causing device failure
Solution Approach 1:
The patent introduces a barrier layer as an intermediary substance positioned between the copper source/drain electrodes and the semiconductor layer. This intermediary barrier layer, with density of 7.5 g/cm³ to 10.5 g/cm³, effectively blocks copper atoms from diffusing into the semiconductor layer during thermal processes, while allowing the copper electrodes to maintain their high electrical conductivity
Solution Approach 2:
The patent converts the potentially harmful effect of copper thermal diffusion into a benefit by using the copper's own diffusion tendency to validate the effectiveness of the barrier layer. The barrier layer is designed to be thin enough to allow process integration but dense enough to stop copper diffusion, turning the diffusion problem into a means of verifying barrier performance
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 solution effectively blocks copper diffusion even when the barrier layer is thinned, maintaining the integrity of the semiconductor layer and enhancing the performance and reliability of the thin-film transistor, while allowing for low-cost and workable wet etching processes.
Implementation Method 1
a barrier layer between the semiconductor layer and the source electrode and between the semiconductor layer and the drain electrode
Implementation Method 2
formed using sputtering with nitrogen and argon gases
Data Source
AI summary
A thin-film transistor according to the present disclosure includes: a substrate; a gate electrode above the substrate; a gate insulating layer on the gate electrode; a channel layer on the gate insulating layer which is located on the gate electrode; a source electrode above the channel layer; a drain electrode above the channel layer; and a barrier layer between the channel layer and the source electrode and between the channel layer and the drain electrode. Each of the source electrode and the drain electrode is made of a metal including copper, and the barrier layer contains nitrogen and molybdenum and has a density greater than 7.5 g/cm3 and less than 10.5 g/cm3.