LCD Oxide TFT Contact-Hole Patterning With Fewer Photomasks
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Solution Overview
Problem
The existing methods for manufacturing liquid crystal display devices require multiple photomasks and complex techniques, leading to increased costs, reduced yield, and potential degradation of electric characteristics, while also limiting the reduction of substrate thickness, which affects the device's thickness, weight, and durability.
Innovation Solution
A method involving the formation of a separation layer, conductive layers, and resist masks to reduce the number of photomasks needed, using oxide semiconductors with reduced impurity concentrations, and copper or aluminum for electrodes to enhance reliability and durability, while transferring the element region to a tougher support for improved mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional manufacturing methods using at least five photomasks are used, then the liquid crystal display device can be manufactured with standard process reliability, but the manufacturing cost increases and the manufacturing process becomes more complex
Solution Approach 1:
The patent combines multiple photomask processes into a single photomask process by using a reflective board with a specific reflective layer structure. The reflective layer is formed to have different reflective properties in different regions, allowing multiple pattern transfers to be achieved simultaneously through one photomask exposure process, thereby reducing process complexity while maintaining reliability
Solution Approach 2:
The patent introduces a reflective board with a specially designed reflective layer as an intermediary element. This reflective board serves as a mediator that enables the transfer of multiple patterns through a single photomask by controlling light reflection in different regions, thus simplifying the manufacturing process without sacrificing pattern definition quality
2Length of moving object
If substrate thickness is reduced by mechanical polishing or chemical polishing, then the liquid crystal display device becomes thinner and lighter, but the substrate strength decreases and the device becomes more susceptible to damage
Solution Approach 1:
The patent changes the material parameter of the substrate from traditional glass to a resin film, which has inherently better toughness and impact resistance. This material parameter change allows the substrate to be made thinner while maintaining or improving its mechanical strength and damage resistance, directly resolving the contradiction between thickness reduction and strength maintenance
Data Source
AI summary
Provided is a method to manufacture a liquid crystal display device in which a contact hole for the electrical connection of the pixel electrode and one of the source and drain electrode of a transistor and a contact hole for the processing of a semiconductor layer are formed simultaneously. The method contributes to the reduction of a photography step. The transistor includes an oxide semiconductor layer where a channel formation region is formed.