Oxide Semiconductor Thin Film Transistor Drain Contact Structure
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Solution Overview
Problem
The existing methods for forming thin film transistors with oxide semiconductor films result in high resistance, leading to leakage, high threshold values, and insufficient long-term reliability, as well as unsatisfactory display quality due to the reduction in resistance of the oxide semiconductor film and inadequate protection, causing contact failures between the drain and pixel electrodes.
Innovation Solution
A thin film transistor substrate configuration where the drain section is a low resistance portion of the oxide semiconductor film, with a reduced thickness, ensuring reliable contact with the pixel electrode and improved conductivity, and including a source section made of source metal stacked above the gate insulating film, reducing the risk of contact failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-layer metal structure is used for the drain electrode, then the conductivity improves, but the contact hole formation becomes complex and may expose aluminum to etching gas
Solution Approach 1:
The invention extracts the aluminum layer from the contact path by forming the pixel contact hole to reach the oxide semiconductor film directly, bypassing the need to penetrate through the multi-layer metal structure. This simplifies the contact hole formation process while maintaining the benefits of the multi-layer drain electrode structure for conductivity.
Solution Approach 2:
The oxide semiconductor film serves as an intermediary conductive element between the multi-layer drain electrode and the pixel electrode. The drain electrode maintains its multi-layer structure for optimal conductivity, while the oxide semiconductor film provides a direct contact path that avoids exposing aluminum to etching gas, thus simplifying the overall contact formation process.
Data Source
AI summary
A source section (S) is made of a source metal (25s) provided above a gate insulating film (23) and an oxide semiconductor film (24a), and a drain section (DR) includes a low resistance portion (24ad) which is part of the oxide semiconductor film (24a), where the part includes a surface of the oxide semiconductor film (24a) opposite to the gate insulating film (23), and the resistance of the part is reduced.