LCD Pixel Electrode Dual-Layer Etching Aperture Ratio
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Solution Overview
Problem
Existing LCD devices face challenges in achieving high aperture ratios and reducing etching time due to etching non-uniformity, metal damage, and high reflectivity, which limits brightness and productivity.
Innovation Solution
The implementation of a dual-layer structure comprising a metal layer and a metal insulation layer for pixel electrodes, allowing for faster etching and uniform micro-line formation, thereby enhancing aperture ratio and reducing etching time while minimizing metal layer exposure and reflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single metal layer is used for pixel electrodes, then the structure is simple and manufacturing is easier, but etching time is lengthy and etching non-uniformity occurs
Solution Approach 1:
The pixel electrode structure is segmented into two distinct layers: a lower metal layer (aluminum or aluminum alloy) and an upper metal layer (molybdenum titanium alloy). This segmentation allows each layer to be optimized for different functions - the lower layer provides structural foundation while the upper layer enables precise micro-patterning with narrower line-widths, thereby reducing etching time and improving productivity without compromising manufacturing feasibility
Solution Approach 2:
The patent employs composite materials by combining two different metal alloys in a layered structure. The lower layer uses aluminum or aluminum alloy for cost-effectiveness and basic conductivity, while the upper layer uses molybdenum titanium alloy for superior etching characteristics and micro-line formation. This composite approach resolves the contradiction by achieving both ease of manufacture (through material selection) and high productivity (through enhanced etching performance)
2Manufacturing precision
If etching time is extended to achieve complete pattern formation, then micro-line formation completeness improves, but productivity decreases and metal damage increases
Solution Approach 1:
The etching process is segmented into two stages corresponding to the two metal layers. The upper molybdenum titanium layer is etched first to define the micro-line patterns with high precision and narrow line-widths. Then the lower aluminum layer is etched to complete the pixel electrode formation. This segmentation enables complete micro-line formation in a shorter total etching time, thereby improving both manufacturing precision and productivity simultaneously
Solution Approach 2:
The upper metal layer is deposited and patterned first to establish the micro-line geometry before the lower metal layer is processed. This preliminary action ensures that the critical micro-line formation is completed with high precision first, allowing the subsequent lower layer etching to proceed more quickly without compromising pattern completeness, thus resolving the contradiction between precision and productivity
3Reliability
If metal layer reflectivity is high, then electrical conductivity is good, but rainbow spot phenomenon occurs and brightness is reduced
Solution Approach 1:
The patent uses composite materials with different optical properties in the two layers. The lower aluminum layer provides high electrical conductivity and cost-effectiveness. The upper molybdenum titanium layer has lower reflectivity, which reduces the rainbow spot phenomenon and improves brightness. This composite structure resolves the contradiction by maintaining good electrical conductivity through the lower layer while improving illumination intensity through the upper layer's optical characteristics
4Area of stationary object
If aperture ratio is increased by narrowing electrode line-widths, then brightness improves, but etching difficulty increases and process time lengthens
Solution Approach 1:
The electrode structure is segmented into two layers with different etching characteristics. The upper molybdenum titanium layer is specifically designed to enable micro-patterning with narrow line-widths (1.5-2.0 μm) through controlled etching. This segmentation makes it feasible to achieve high aperture ratios by narrowing the visible electrode lines, thereby improving brightness without excessively increasing etching process complexity
Solution Approach 2:
The patent changes the material parameter of the upper metal layer to molybdenum titanium alloy, which has superior etching characteristics compared to traditional single-metal structures. This parameter change enables precise control of line-widths at 1.5-2.0 μm, achieving high aperture ratios while keeping the etching process manageable through optimized etching conditions for the specific material composition
Data Source
AI summary
A liquid crystal display device and a fabrication method thereof, are discussed. According to an embodiment, the liquid crystal display device includes gate lines on a substrate; data lines on the substrate; common lines disposed substantially in parallel to the gate lines; TFTs formed at intersections between the gate and data lines, each of the TFTs including a gate electrode extending from the corresponding gate line, a gate insulation layer, an active layer, an ohmic contact layer, a source electrode extending from the corresponding data line and a drain electrode spaced apart from the source electrode; passivation layers, each formed on the TFT and having a contact hole for exposing a part of the corresponding drain electrode; and pixel electrodes, each composed of a conductive layer and an insulation layer formed on the corresponding passivation layer and electrically connected to the corresponding drain electrode via the corresponding contact hole.