Z-Inversion Display Drain Electrode Overlap for Capacitance Uniformity
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Solution Overview
Problem
In Z-inversion type display devices, capacitance variations between pixels occur due to misalignment of gate and source/drain electrode layers, leading to nonuniformity, flickering, and vertical line defects, which complicates mass production and quality control.
Innovation Solution
The solution involves forming a Z-inversion type display device where the drain electrode completely overlaps the gate line, ensuring consistent capacitance across pixels, thereby eliminating capacitance variations and reducing misalignment issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the drain electrode is formed with misalignment relative to the gate line, then the manufacturing process is simpler, but capacitance variations occur between pixels causing nonuniformity and defects
Solution Approach 1:
The gate line width is designed to be greater than the drain electrode width in advance, creating a built-in tolerance margin that prevents capacitance variations even when misalignment occurs during manufacturing. This preliminary design decision eliminates the need for precise alignment control while ensuring capacitance uniformity.
Solution Approach 2:
The gate line width parameter is specifically increased relative to the drain electrode width parameter. This parameter change creates a geometric configuration where the gate line completely covers the drain electrode, transforming the alignment sensitivity issue into a robust design that tolerates manufacturing variations.
2Manufacturing precision
If secondary compensation processes are implemented to correct capacitance variations, then pixel uniformity improves, but manufacturing complexity and time increase
Solution Approach 1:
The design accepts that misalignment will occur during manufacturing but converts this potential harm into a benefit by designing the gate line to be wider than the drain electrode. This ensures that even with misalignment, the gate line completely covers the drain electrode, maintaining capacitance uniformity without requiring compensation processes.
Solution Approach 2:
The geometric design of the gate line and drain electrode relationship creates a self-compensating system. The wider gate line automatically compensates for any misalignment that occurs during manufacturing, eliminating the need for secondary compensation processes and maintaining productivity.
3Manufacturing precision
If the gate line width is increased to completely cover the drain electrode, then capacitance uniformity improves, but material consumption increases
Solution Approach 1:
The gate line width is increased only in the specific region where it intersects with the drain electrode, rather than increasing the entire gate line width. This localized quality change ensures complete coverage of the drain electrode while minimizing additional material consumption in non-critical regions.
Data Source
AI summary
The present invention provides a Z-inversion type display device comprising a gate line and a data line that intersect with each other to define a pixel area on a substrate, a thin film transistor that includes a gate electrode, a semiconductor layer, a source electrode and a drain electrode, and a pixel electrode that is formed in the pixel area, and is electrically connected to the drain electrode of the thin film transistor, wherein the drain electrode completely overlaps the gate line such that a drain electrode area is wholly included in a gate line area on a plan view.