Stepped Holes in Array Substrate Insulation Layer
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Solution Overview
Problem
The challenge in display technology is that a thick insulation layer in array substrates, required for signal transmission, leads to incomplete etching and lapping defects due to excessive thickness, causing residual photoresist and stress in metal lines, which affects the yield and stability of electrical connections.
Innovation Solution
The introduction of stepped holes in the insulation layer with a radius difference of 0.2 μm to 0.6 μm between the bottom and top, and a gradient angle of 50° to 75°, reduces internal stress and improves the lapping effect by providing a cushioning effect for the metal, preventing broken connections and enhancing the yield of the array substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the insulation layer is increased to cover thicker metallic lines for signal transmission, then the insulation capability is improved, but the etching process becomes incomplete and produces residues
Solution Approach 1:
The single thick insulation layer is segmented into multiple thinner layers (first insulation layer and second insulation layer). Each layer can be completely etched without residues while collectively providing the required insulation capability. The etching process is divided into separate steps for each layer, ensuring complete removal without photoresist residues.
Solution Approach 2:
The solution transitions from a single-thickness dimension to a multi-layer dimensional structure. By stacking multiple thinner insulation layers, the total insulation thickness is achieved while each individual layer maintains etchability. This dimensional restructuring allows simultaneous achievement of both insulation capability and etching completeness.
2Reliability
If the thickness of the metallic line is increased to meet signal transmission requirements, then the signal transmission capability is improved, but the insulation layer thickness must also increase leading to etching defects
Solution Approach 1:
The insulation structure is segmented into multiple layers, allowing each layer to be etched completely without residues. This segmentation eliminates the harmful etching defects while maintaining the total insulation thickness required for the thicker metallic lines.
Solution Approach 2:
The insulation layers are prepared in a stacked configuration before the etching process. The first insulation layer is formed and etched completely, then the second insulation layer is formed and etched completely. This preliminary structuring ensures that each layer can be processed independently without generating residues or lapping defects.
Data Source
AI summary
An array substrate includes an insulation layer and one or more stepped holes each penetrating through the insulation layer in a direction perpendicular to the insulation layer. Each stepped hole includes a first hole and a second hole under the first hole, a radius of the first hole at a bottom is a first radius, a radius of the second hole at a top is a second radius which is substantially smaller than the first radius, and a difference between the first radius and the second radius is 0.2 μm to 0.6 μm.