High-Aspect-Ratio Groove Substrate for Sub-2 μm Thick Metal Traces
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Solution Overview
Problem
Existing manufacturing processes struggle to produce metal mesh transparent conductive films with a line width less than 2 μm and a thickness greater than 2 μm, as they either result in wider lines due to lithography limitations or cause the lines to collapse.
Innovation Solution
A substrate design with a groove in the insulating layer having a depth greater than 2 μm and a width ratio greater than 1, combined with a metal trace within the groove matching the groove's depth, is used to form a metal trace with a thickness greater than 2 μm and a line width less than 2 μm, achieved through controlled deposition and etching of insulating layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the line width of the metal mesh is reduced to less than 2 μm to improve transmittance, then the transmittance is improved, but the thickness of the metal mesh cannot be increased to satisfy the resistivity requirement
Solution Approach 1:
The patent transitions from a planar metal mesh structure to a three-dimensional structure by forming grooves in the insulating layer and placing metal traces within these grooves. This vertical dimensionality change allows the metal trace to achieve greater effective thickness (filling the groove depth) while maintaining a narrow line width at the surface, thereby simultaneously improving transmittance and satisfying resistivity requirements.
Solution Approach 2:
The metal trace is nested within the groove structure formed in the insulating layer. The groove acts as a container that holds the metal trace, allowing the metal to occupy the vertical space within the groove while maintaining a controlled horizontal footprint. This nesting approach enables the metal trace to achieve the required thickness equivalent to the groove depth while keeping the line width below 2 μm.
2Manufacturing precision
If conventional manufacturing processes are used to form narrow metal lines, then the line width can be controlled, but the lines collapse or cannot achieve sufficient thickness
Solution Approach 1:
The groove structure is formed in the insulating layer before the metal trace is deposited. This preliminary action creates a pre-defined three-dimensional space that guides and supports the metal trace formation. The groove walls provide lateral confinement that prevents line collapse during subsequent processing steps, while the groove depth pre-determines the maximum achievable metal trace thickness.
Solution Approach 2:
The insulating layer is modified locally by forming grooves only in specific regions where metal traces are to be placed. This local modification creates areas with different structural properties - the grooved regions provide enhanced support and confinement for the metal traces, while other regions maintain the original planar insulating layer structure. This localized approach enables precise control over metal trace geometry and stability.
Data Source
AI summary
A substrate, a method for manufacturing the substrate, a display device, and an electronic apparatus are provided. The substrate includes: a base; an insulating layer on the base, and a metal trace, wherein a groove is arranged in a side surface of the insulating layer distal to the base, the depth of the groove is greater than 2 μm, a ratio of the depth to the width of the groove is greater than 1, and the width is the dimension of a longitudinal section of the groove in a first direction, the first direction is parallel to the base; the depth is a dimension of a longitudinal section of the groove in a second direction, the second direction is perpendicular to the base; the metal trace is within the groove, and a thickness of the metal trace is equal to or substantially equal to the depth of the groove.