Display Panel Signal Line Etch Selectivity and Reflectance
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Solution Overview
Problem
Display panels face issues with high external light reflectance due to conductive layers, affecting image visibility and process reliability, particularly because non-uniform side surfaces of signal lines can damage insulating layers and increase reflectance.
Innovation Solution
A display panel design featuring a signal line structure with an upper layer having an etch selectivity of 0.5 to 3 with respect to a lower layer, where the upper layer is thin (≤100 angstroms) and may include the same material as a second layer with lower specific resistance, reducing light reflectance and improving process reliability by aligning side surfaces along a virtual line inclined to the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the signal line uses a conventional multi-layer conductive structure, then the electrical conductivity is improved, but the external light reflectance increases and the side surface uniformity deteriorates
Solution Approach 1:
The patent applies local quality by making the upper layer thickness position-dependent: thinner at the side surfaces (≤100 angstroms) to reduce reflectance and improve uniformity, and thicker in the center region to maintain electrical conductivity. This spatial variation in thickness resolves the contradiction between conductivity and reflectance.
Solution Approach 2:
The patent changes the thickness parameter of the upper layer from a uniform structure to a non-uniform structure with controlled thickness variation. By limiting the upper layer thickness to ≤100 angstroms at side surfaces while maintaining adequate thickness in the center, the patent achieves both low reflectance and high conductivity.
2Reliability
If the upper layer thickness is increased to improve electrical conductivity, then the conductivity is improved, but the light reflectance increases and visibility of signal lines worsens
Solution Approach 1:
The patent implements local quality by differentiating the upper layer thickness between side surface regions and center regions. The side surfaces have reduced thickness (≤100 angstroms) to minimize light reflection and improve visual appearance, while the center maintains sufficient thickness for electrical conductivity.
Solution Approach 2:
The patent transitions from a single uniform thickness dimension to a two-dimensional thickness distribution. The upper layer thickness varies across the surface area, being thin at edges and thicker in the center, thus satisfying both optical and electrical requirements simultaneously.
3Ease of manufacture
If the side surfaces of the signal line are non-uniform, then the manufacturing process is simpler, but the insulating layer integrity deteriorates and process reliability worsens
Solution Approach 1:
The patent applies preliminary action by pre-controlling the upper layer thickness at the side surfaces to be ≤100 angstroms during the deposition process. This preliminary thickness control ensures that subsequent insulating layer deposition and processing do not cause damage from non-uniform side surfaces, thereby maintaining insulating layer integrity.
Solution Approach 2:
The patent provides beforehand cushioning by designing the upper layer with reduced thickness at side surfaces, which acts as a buffer that prevents stress concentration and damage to the insulating layer during subsequent manufacturing processes, thus protecting insulating layer integrity.
4Object-affected harmful factors
If the upper layer thickness is reduced to minimize light reflectance, then the reflectance is reduced, but the electrical conductivity deteriorates
Solution Approach 1:
The patent implements local quality by creating a thickness gradient in the upper layer: thin at side surfaces (≤100 angstroms) to reduce reflectance, and thicker in the center region to maintain electrical conductivity. This spatial differentiation resolves the contradiction between optical and electrical performance.
Solution Approach 2:
The patent moves from a one-dimensional uniform thickness parameter to a two-dimensional thickness distribution. The upper layer thickness varies across the surface, being minimal at edges for optical performance and sufficient in the center for electrical performance, thus satisfying both requirements.
Data Source
AI summary
A display panel includes a base substrate, a pixel including a thin film transistor and a display element, a first signal line connected to the pixel, and a second signal line disposed on a layer different from the first signal line. At least one of the first signal line and the second signal line includes a lower layer including a conductive material and an upper layer disposed on the lower layer and including a conductive material. The upper layer has an etch selectivity in a range equal to or greater than about 0.5 and equal to or smaller than about 3 with respect to the lower layer.