Liquid Crystal Display Electrode Thickness Ratio for Etching Control
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Solution Overview
Problem
In liquid crystal display devices, the wet etching process for patterning electric conductive layers can lead to uneven removal, resulting in tapered ends of electrodes and wiring, which worsens coverage characteristics and may cause short circuits, thereby lowering manufacturing yield.
Innovation Solution
The use of a specific thickness ratio between the first and second electric conductive layers, where the first layer (e.g., molybdenum, titanium, or chromium) is equal to or less than 10% of the second layer (aluminum) thickness, ensures tapered ends and prevents uneven removal during wet etching, maintaining coverage and avoiding short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet etching process is used to pattern electric conductive layers, then manufacturing process is simplified, but uneven removal of layers occurs causing tapered ends and short circuits
Solution Approach 1:
The patent changes the physical parameter of the electric conductive layer by forming a tapered structure with controlled thickness ratio (first layer thickness ≤ 10% of second layer thickness). This parameter change ensures uniform etching removal and prevents reverse taper formation, resolving the contradiction between manufacturing simplicity and precision.
Solution Approach 2:
The patent performs preliminary action by pre-forming the tapered structure and thickness ratio before the wet etching process. This preliminary preparation ensures that during etching, the layers are removed uniformly without causing coverage deterioration or short circuits, thus maintaining both manufacturing ease and precision.
2Reliability
If first electric conductive layer thickness is increased, then electrode conductivity is improved, but reverse taper formation occurs during wet etching
Solution Approach 1:
The patent optimizes the thickness parameter by establishing a specific ratio relationship (first layer ≤ 10% of second layer). This parameter control ensures sufficient conductivity through the first layer while preventing reverse taper formation during etching, as the thin first layer removes uniformly without creating protruding ends.
Solution Approach 2:
The patent uses a composite structure of two different electric conductive layers with distinct thickness ratios. The first layer (e.g., Mo, Ti, Ni, Cr) and second layer (e.g., Al) work together, where the thin first layer provides conductivity while the thicker second layer prevents reverse taper, achieving both reliability and proper shape.
3Reliability
If insulating layer coverage is improved, then short circuit prevention is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-forming the tapered electrode structure with controlled thickness ratio before depositing the insulating layer. This preliminary preparation ensures that the insulating layer naturally achieves good coverage without requiring additional complex manufacturing steps, thus enhancing short circuit prevention without increasing device complexity.
Data Source
AI summary
In one embodiment, a liquid crystal display device includes an array substrate having a sensor electrode and a plurality of pixel electrodes, and a counter substrate facing the array substrate. The sensor electrode includes an electric conductive oxide layer, a first electric conductive layer arranged on the electric conductive oxide layer and formed of one metal selected from the group consisting of molybdenum (Mo), titanium (Ti), nickel (nickel), and chromium (Cr), and a second electric conductive layer arranged on the first electric conductive layer and formed of aluminum. The plurality of pixel electrodes is arranged on the sensor electrode in a matrix shape so as to face the electric conductive oxide layer. Each pixel electrode is provided with slits. The thickness of the first electric conductive layer is equal to or less than 10% of the thickness of the second electric conductive layer.