Zigzag Pad Contact Holes for LCD Alignment
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Solution Overview
Problem
Existing LCD devices face challenges in forming precise contact holes on pad portions due to side contacts and high fabrication costs associated with photolithography processes, particularly in roll printing methods where embossed patterns are difficult to form accurately, leading to misalignment and undercuts during the etching process.
Innovation Solution
A printing plate with embossed patterns in a zigzag or oblique line format is used to form contact holes on pad portions, allowing for precise transfer of PR patterns and reducing misalignment, while varying linewidths in pad unit portions help in minimizing contact resistance and fabrication costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography process is used to form contact holes on pad portions, then manufacturing precision can be improved, but fabrication cost increases significantly
Solution Approach 1:
The patent uses embossed patterns on a printing plate as a physical copy/master template to transfer patterns onto photoresist-coated substrates via roll printing. This copying approach replaces the need for expensive photolithography masks while achieving comparable pattern transfer precision for contact hole formation on pad portions.
Solution Approach 2:
The patent replaces the optical system of photolithography (requiring photomasks, UV exposure equipment, and complex alignment systems) with a mechanical roll printing system that uses embossed patterns and pressure-based transfer. This mechanical substitution significantly reduces equipment cost and process complexity while maintaining manufacturing precision.
2Ease of manufacture
If embossed patterns are formed in straight line format for roll printing, then fabrication cost is reduced, but misalignment and undercuts occur during etching process
Solution Approach 1:
The patent transitions from symmetric straight-line embossed patterns to asymmetric zigzag or oblique line patterns. This asymmetry in pattern geometry allows the photoresist to be transferred more accurately during roll printing, preventing misalignment and undercut issues that occur with straight-line patterns while maintaining the cost benefits of roll printing.
Solution Approach 2:
The patent introduces curved or angled zigzag patterns instead of straight lines. This curvature in the embossed pattern design improves the transfer fidelity during rolling contact, ensuring that contact holes are formed with proper alignment and without undercuts, thereby resolving the precision issue while keeping fabrication costs low.
3Object-affected harmful factors
If pad metallic film is formed of Molybdenum to comply with environmental regulations, then environmental compliance is achieved, but side contact occurs between transparent conductive film and pad metallic film
Solution Approach 1:
The patent addresses the side contact issue by changing the dimensional arrangement of contact holes from a single-line configuration to a multi-dimensional zigzag or oblique pattern. This dimensional change in hole distribution improves the connection between the transparent conductive film and Molybdenum pad metallic film, reducing contact resistance while maintaining environmental compliance.
Solution Approach 2:
The patent applies different local qualities to different regions of the pad portion by creating contact holes in zigzag or oblique patterns rather than uniform straight lines. This local variation in contact hole distribution optimizes the electrical connection in critical areas while maintaining the benefits of using Molybdenum as the environmentally compliant pad metallic film material.
Data Source
AI summary
A LCD device and its fabrication method as discussed. According to an embodiment, the LCD device includes a plurality of gate lines and data lines arranged on a substrate to define a plurality of unit pixels; thin film transistors (TFTs) each formed at an intersecting region of the gate lines and the data lines; a plurality of gate pad portions and data pad portions formed at end portions of the gate lines and the data lines, respectively, at least one of the gate and data pad portions being made up of at least two pad unit portions, each pad unit portion having at least one contact hole such that the contact holes of one of the plurality of gate or data pad portions are arranged in a zigzag or an oblique line format; and pixel electrodes formed at the unit pixels.