Display Substrate Reflective Layer Layout for TFT Etching Completeness
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Solution Overview
Problem
The manufacturing process of thin film transistors (TFTs) for active matrix organic light emitting diodes (AMOLEDs) often results in short circuits between TFTs, leading to a decrease in the yield of display substrates due to incomplete etching of active patterns during the formation process.
Innovation Solution
A display substrate design that includes a reflective layer covering gaps between active patterns, enhancing light exposure and intensifying photoresist exposure, which allows for more complete etching and reduces the likelihood of residual material and short circuits between TFTs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the distance between adjacent active patterns is reduced to increase TFT density, then the pixel density is improved, but the etching completeness deteriorates leading to short circuits
Solution Approach 1:
The patent applies local quality by creating different gap configurations at different locations. Specifically, the first gap between adjacent active patterns in the same pixel is designed to be smaller than the second gap between active patterns of different pixel units. This local differentiation allows sufficient etching distance in the second gap while maintaining high density through the smaller first gap, thereby resolving the contradiction between pixel density and etching completeness.
Solution Approach 2:
The patent introduces a dimensional solution by varying gap sizes in different spatial directions and locations. By distinguishing between gaps within the same pixel (first gap) and gaps between different pixels (second gap), the design operates in multiple dimensional considerations simultaneously, achieving both high density and complete etching through strategic dimensional differentiation.
2Manufacturing precision
If the gap between active patterns is increased to ensure complete etching, then the etching completeness is improved, but the pixel density decreases
Solution Approach 1:
The patent implements local quality by making the gap size location-dependent. The first gap (within-pixel) is made smaller to maximize density, while the second gap (between-pixel) is made larger to ensure etching completeness. This localized differentiation of gap qualities allows the system to achieve both high pixel density and complete etching without requiring uniform large gaps throughout.
3Manufacturing precision
If photoresist exposure time is increased to improve etching completeness, then the etching completeness is improved, but the manufacturing time increases
Solution Approach 1:
The patent applies preliminary action by pre-optimizing the gap dimensions before the etching process. By designing the first gap and second gap with specific size relationships in advance, the etching process can be completed more efficiently and completely without requiring excessive exposure time. The pre-configured gap structure facilitates better light penetration and etchant access, reducing the time needed to achieve complete etching.
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
The design improves the yield of display substrates by ensuring complete etching of active patterns, reducing the probability of short circuits and enhancing the overall manufacturing process efficiency.
Implementation Method 1
A portion of a first effective pattern that does not overlap with the first signal line has a gap. An orthographic projection of the reflective layer on the substrate covers at least part of a gap of at least one active pair
Data Source
AI summary
A display substrate includes a substrate, a reflective layer, a plurality of first signal lines, and an active layer that are stacked in sequence. The active layer includes a plurality of active pairs, and an active pair includes two active patterns. An orthographic projection of an active pattern on the substrate overlaps with an orthographic projection of a first signal line on the substrate, and a portion of the active pair that does not overlap with the first signal line has a gap. An orthographic projection of the reflective layer on the substrate covers at least part of a gap of at least one active pair.