TFT Array Substrate Single Patterning Process
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Solution Overview
Problem
In the manufacturing of oxide semiconductor thin-film transistors (TFTs), the diffusion of metallic ions from Cu-based metal source/drain electrode layers into the oxide semiconductors can degrade the characteristics of TFTs, requiring an additional buffer layer which increases production complexity and cost.
Innovation Solution
A method involving a single patterning process to form a stack layer of a transparent conductive film and a Cu-based metal film on the oxide semiconductor layer, where the transparent conductive film contacts the oxide semiconductor layer, simultaneously forming source, drain, and pixel electrodes, thereby preventing metallic ion diffusion and reducing the need for a separate buffer layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Cu-based metal source/drain electrode layer is used, then electrical conductivity is improved, but metallic ion diffusion into oxide semiconductor occurs degrading TFT characteristics
Solution Approach 1:
The patent introduces a transparent conductive oxide layer as an intermediary between the Cu-based metal source/drain electrode and the oxide semiconductor. This intermediate layer acts as a diffusion barrier that prevents metallic ion diffusion while maintaining electrical conductivity, thus resolving the contradiction between using Cu-based metals for conductivity and preventing ion diffusion to maintain TFT characteristics.
2Reliability
If an additional buffer layer is added to prevent metallic ion diffusion, then TFT characteristics are protected, but production complexity and cost increase
Solution Approach 1:
The patent makes the transparent conductive oxide layer serve multiple functions simultaneously: it provides electrical conductivity for the source/drain electrode, acts as a diffusion barrier to prevent metallic ion diffusion, and eliminates the need for separate buffer layers. This multi-functionality reduces production complexity and process steps while maintaining TFT characteristics.
3Manufacturing precision
If multiple photolithography processes are used for precise electrode formation, then manufacturing precision is improved, but production time and cost increase
Solution Approach 1:
The patent combines the formation of source/drain electrodes and pixel electrodes into a single photolithography process by using a unified transparent conductive oxide layer patterned in one step. This merging of processes maintains manufacturing precision while significantly reducing production time and eliminating the need for multiple alignment steps.
Data Source
AI summary
A method of manufacturing a thin-film transistor (TFT) array substrate, including: forming a gate layer, a gate insulating layer, an oxide semiconductor layer, a source/drain electrode layer and a pixel electrode layer on a base substrate. The step of forming the source/drain electrode layer and the pixel electrode layer includes: forming a transparent conductive film and a first metallic film on the oxide semiconductor layer in sequence, to form a stack layer of the transparent conductive film and the first metallic film, in which the transparent conductive film contacts the oxide semiconductor layer; and forming source electrodes, drain electrodes and pixel electrodes by a single patterning process on the stack layer of the transparent conductive film and the first metallic film. One patterning process is saved, the production time is shortened, and the production cost is reduced.