Thin Film Transistor Drain Electrode Active Layer Protection
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Solution Overview
Problem
Oxide thin film transistors of the back-channel-etching type lack protection for the active layer, making it vulnerable to subsequent manufacturing processes and environments, which affects their performance.
Innovation Solution
The thin film transistor design includes a drain electrode that completely covers one end of the active layer, with specific configurations such as rectangular or connected electrodes, to provide maximum protection and reduce gate/drain capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If no etch stopping layer is arranged between source/drain electrode and active layer, then device structure is simpler, but active layer is adversely affected by subsequent manufacturing process and environment
Solution Approach 1:
The drain electrode is designed to completely cover the second end of the active layer, serving as an intermediary protective layer between the active layer and the external environment. This covering structure protects the active layer from adverse effects of subsequent manufacturing processes and environmental factors without requiring an additional etch stopping layer, thus maintaining structural simplicity while improving reliability
Solution Approach 2:
The drain electrode performs multiple functions: it serves as both the electrical contact component and the protective covering layer for the active layer. By making the drain electrode extend beyond and completely cover the active layer end, it simultaneously provides electrical connection and environmental protection, eliminating the need for a separate protective layer
2Reliability
If drain electrode completely covers the active layer, then active layer protection is improved, but gate/drain capacitance increases
Solution Approach 1:
The drain electrode is designed with different widths at different locations: it completely covers the active layer at the second end for protection, but has a narrower width in the overlapping region with the gate electrode to minimize capacitance. This local variation in width optimizes both protection and electrical performance
Data Source
AI summary
The present disclosure provides a thin film transistor and its manufacturing method, an array substrate, a display device. The thin film transistor includes a gate electrode, a gate insulating layer, an active layer, a source electrode and a drain electrode. The source electrode and the drain electrode are formed above the active layer and located at a first end and a second end of the active layer which are opposite to each other, respectively. The drain electrode completely covers the second end of the active layer.