Pixel Drive Circuit Fabrication via Selective Etching
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Solution Overview
Problem
Current pixel driving circuit fabrication methods for AMOLED displays require complex and costly masking processes or intricate etching rate adjustments, which decrease efficiency and increase production complexity when achieving jump layer connections between switching and driving TFTs.
Innovation Solution
A method where the gate, gate insulation, oxide semiconductor, and etching stop layers of both TFTs are fabricated simultaneously, with the drain metal of the switching TFT extending to cover the gate of the driving TFT, followed by a via hole process to expose the driving TFT gate and connect it with an Indium Tin Oxide layer, simplifying the process and reducing the need for multiple masks or etching rate adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If masking process is used to split the GI layer of the driving TFT gate metal, then reliable jump layer connection is achieved, but fabrication cost increases and fabrication efficiency decreases
Solution Approach 1:
The patent extracts and removes the masking step from the fabrication process by using selective etching with different etching rates. The GI layer is selectively removed at the via hole position through chemical etching without requiring a mask, thereby eliminating the masking process while maintaining reliable jump layer connection.
Solution Approach 2:
The patent introduces an intermediary mechanism - selective chemical etching with different etching rates for different metal layers. This intermediary process enables selective removal of the GI layer at specific positions without masks, resolving the contradiction between reliability and efficiency.
2Reliability
If masking process is used to split the GI layer of the driving TFT gate metal, then reliable jump layer connection is achieved, but fabrication cost increases
Solution Approach 1:
The patent removes the masking step from the fabrication process by using selective etching with different etching rates. This extraction of the masking process directly reduces fabrication cost while maintaining reliable jump layer connection through the alternative selective etching mechanism.
3Reliability
If dry etching with different etching rates is used to remove GI layer and protection layer, then jump layer connection is achieved, but process complexity increases
Solution Approach 1:
The patent introduces selective chemical etching as an intermediary mechanism that uses different etching rates of materials (Al vs. GI layer) to achieve selective removal without masks. This intermediary approach simplifies the overall process by replacing complex mask-aligned dry etching with a more straightforward wet etching process.
Solution Approach 2:
The patent changes the etching parameter approach by using chemical etching with inherently different etching rates for different materials rather than controlling dry etching parameters. This parameter change from physical to chemical etching reduces process complexity while achieving the same selective removal effect.
4Manufacturing precision
If multiple masks are used for fabricating the pixel driving circuit, then precise pattern formation is achieved, but fabrication efficiency decreases
Solution Approach 1:
The patent extracts and eliminates the masking step from the fabrication process. By using selective etching with different etching rates, precise pattern formation is achieved without masks, thereby removing the bottleneck that reduced fabrication efficiency.
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
This approach increases the aperture ratio of the backplate, reduces process complexity, and ensures a reliable jump layer connection between the switching and driving TFTs, enhancing fabrication efficiency and reducing costs.
Implementation Method 1
an Indium Tin Oxide ITO layer connecting the drain of the switching TFT and the gate of the driving TFT at the via hole
Implementation Method 2
the drain metal of the switching TFT extending and covering the GI layer on the gate of the driving TFT by etching
Data Source
AI summary
The application discloses a pixel driving circuit and a fabrication method thereof as well as an array substrate, the pixel driving circuit including a switching and a driving TFT, the method including: on a substrate, fabricating a gate, a gate insulation GI layer, an oxide semiconductor layer, and an etching stop ESL layer simultaneously in turn; depositing simultaneously source/drain metals of the switching TFT and the driving TFT, the drain metal of the switching TFT extending and covering the GI layer on the gate of the driving TFT by etching; depositing a protection layer; etching off the protection layer, the drain metal of the switching TFT and the GI layer at a via hole by using a via hole process, to expose the gate of the driving TFT; depositing an ITO layer connecting the drain of the switching TFT and the gate of the driving TFT at the via hole.