Oxide TFT Substrate Alignment Mark Formation
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Solution Overview
Problem
High-temperature thermal treatment in the fabrication of oxide semiconductor-based thin-film transistor (TFT) substrates leads to substrate shrinkage and misalignment issues, causing light leakage and process failures.
Innovation Solution
A method is introduced where an alignment mark is provided after the thermal treatment process, using multiple deposition layers patterned with a halftone mask to prevent shrinkage and misalignment, ensuring accurate alignment of subsequent layers and electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature thermal treatment is performed on the oxide semiconductor layer, then the semiconductor properties are improved, but substrate shrinkage and misalignment occur
Solution Approach 1:
The alignment mark is formed before the thermal treatment process. This preliminary action ensures that the alignment reference is established when the substrate is still at its original dimensions, allowing subsequent layers to be aligned relative to this pre-formed mark rather than to the shrunk substrate features
Solution Approach 2:
The alignment mark is formed as a separate, distinct structure from the active device patterns. By segmenting the alignment reference from the functional patterns, the mark can serve its alignment purpose without being affected by the shrinkage that occurs during thermal treatment of the oxide semiconductor layer
2Ease of manufacture
If alignment mark is provided before thermal treatment, then the process is simpler, but the alignment mark shrinks and causes misalignment
Solution Approach 1:
The alignment mark is formed in advance of the thermal treatment, establishing a stable reference point before substrate shrinkage occurs. This preliminary formation allows the mark to maintain its original dimensions and position relationship with other structures
Solution Approach 2:
The alignment mark serves as an intermediary reference element that mediates between the pre-thermal-treatment substrate geometry and the post-thermal-treatment device features. Subsequent layers are aligned to this intermediary mark rather than directly to the shrunk substrate features
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 effectively prevents misalignment and process failures, maintaining the structural integrity and performance of the TFT substrate and display device.
Implementation Method 1
performing a thermal treatment process to the oxide semiconductor layer
Implementation Method 2
exposing and developing the photosensitive film and providing first and second photosensitive film portions
Data Source
AI summary
A method of fabricating a thin-film transistor substrate includes disposing an oxide semiconductor layer on an insulating substrate, performing a thermal treatment process to the oxide semiconductor layer, providing an alignment mark, a source electrode, a drain electrode, and an oxide semiconductor pattern, after the thermal treatment process, providing a gate electrode, after the thermal treatment process, and providing a pixel electrode connected to the drain electrode.