TFT Array Substrate Without Passivation Layer
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Solution Overview
Problem
The existing TFT array substrates for liquid crystal display devices require a passivation layer, which increases manufacturing costs and can lead to galvanic corrosion of data pads and image quality degradation due to the complexity of the manufacturing process and the use of multiple mask processes.
Innovation Solution
A TFT array substrate and fabrication method that eliminates the need for a passivation layer by using a jumping structure for data pads and channel passivation, reducing the number of mask processes and incorporating a static electricity prevention structure to separate even and odd data lines, thereby reducing manufacturing costs and preventing galvanic corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passivation layer is used to protect TFTs, then TFT reliability is improved, but manufacturing cost increases and galvanic corrosion of data pads occurs
Solution Approach 1:
The patent removes the passivation layer from the manufacturing process entirely. Instead of adding a protective layer, the invention uses a different approach by forming the data pad with a jumping structure that connects to the data line through a contact hole, eliminating the need for passivation and thereby reducing manufacturing cost and preventing galvanic corrosion.
Solution Approach 2:
Instead of protecting the TFT with a passivation layer (conventional approach), the patent inverts the approach by making the data pad structure itself resistant to corrosion through the jumping structure design, where the data pad is separated from the data line and connected through an insulating layer with a contact hole, thus preventing galvanic corrosion without requiring passivation.
2Manufacturing precision
If multiple mask processes are used to fabricate TFT array substrate, then manufacturing precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the data pad formation with the data line formation in a single mask process. The jumping structure is formed using the same mask pattern as the data line, eliminating the need for separate mask processes for data pad fabrication. This merging of processes reduces device complexity and manufacturing cost while maintaining precision.
Solution Approach 2:
The mask pattern used for data line formation serves multiple functions: it defines both the data line and the jumping structure that connects to the data pad. This multi-functionality reduces the number of mask processes required while maintaining manufacturing precision.
Data Source
AI summary
A TFT array substrate is provided. The TFT array substrate includes: a gate electrode connected to a gate line; a source electrode connected to a data line that crosses the gate line and defines a pixel region; a drain electrode facing the source electrode with a channel between; a semiconductor layer forming the channel in between the source electrode and the drain electrode; a pixel electrode in the pixel region and contacting the drain electrode; a channel passivation layer formed on the semiconductor layer; a gate pad with a gate pad lower electrode that extends from the gate line; and a data pad having a data pad lower electrode separated from the data line.