Pixel Structure With Variable Channel Thickness For LCD View Angle
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Solution Overview
Problem
Current LCD manufacturing techniques for achieving wide view angles are complex and result in low production yield, increased manufacturing costs, and issues like light leakage due to the need for additional mask processes and alignment protrusions or slits.
Innovation Solution
A pixel structure with a substrate, gate, gate insulating layer, channel layer, source/drain layers, and pixel electrodes, where the channel layer has different thicknesses to achieve varying liquid crystal alignments without additional alignment structures, allowing for simpler fabrication and higher yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alignment protrusions or slits are formed on substrates using additional mask processes to achieve wide view angle (MVA), then liquid crystal alignment is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention extracts and removes the additional mask process from the fabrication sequence by forming the pixel electrode pattern and alignment protrusion pattern simultaneously in a single photolithography step. This eliminates the separate alignment structure formation step while maintaining the MVA alignment effect.
Solution Approach 2:
The invention merges the pixel electrode pattern formation and alignment protrusion pattern formation into a single photolithography and etching process. The pixel electrode and alignment protrusions are created together using one mask pattern, combining two functions into one fabrication step.
2Reliability
If additional mask processes are used to form alignment protrusions for wide view angle, then liquid crystal alignment is improved, but production yield decreases
Solution Approach 1:
The additional mask process is extracted and removed from the fabrication sequence. The alignment protrusions are formed in the same photolithography step as the pixel electrode, eliminating the source of yield loss associated with multiple masking steps.
Solution Approach 2:
The alignment protrusion pattern is predetermined and formed simultaneously with the pixel electrode pattern in the initial photolithography step. This preliminary formation of both structures together prevents subsequent alignment issues that would reduce yield.
3Reliability
If alignment protrusions or slits are formed on substrates to achieve wide view angle, then liquid crystal alignment is improved, but manufacturing cost increases
Solution Approach 1:
The formation of pixel electrodes and alignment protrusions is merged into a single fabrication process using one mask pattern. This reduces material consumption (photoresist, masks) and process steps, directly lowering manufacturing costs while maintaining alignment functionality.
Solution Approach 2:
The additional mask process and separate alignment structure formation steps are extracted and removed. This simplification reduces fabrication cost by eliminating expensive photolithography materials and processing steps.
4Illumination intensity
If additional mask processes are used for forming alignment structures, then wide view angle is achieved, but light leakage in dark state occurs
Solution Approach 1:
The pixel electrode pattern and alignment protrusion pattern are preliminarily formed together in a single photolithography step with precise pattern definition. This ensures proper pattern formation without the light leakage issues that can arise from multiple masking steps and subsequent alignment operations.
5Reliability
If alignment protrusions are formed on substrates to achieve wide view angle, then liquid crystal alignment is improved, but optical transmittance of backlight sources decreases
Solution Approach 1:
The pixel electrode and alignment protrusions are formed together in a single etching step from the same mask pattern. This reduces the total number of etching steps and material deposition layers, minimizing light scattering and absorption, thereby improving optical transmittance while maintaining alignment functionality.
Data Source
AI summary
A pixel structure and a fabrication method thereof are provided. The pixel comprises a substrate, a gate, a gate insulating layer, a channel layer, a first source/drain, a second source/drain, a dielectric layer, a first pixel electrode, and a second pixel electrode. The gate is disposed on the substrate and is covered by the gate insulating layer. The channel layer is disposed on the gate insulating layer above the gate. The first source/drain and the second source/drain are disposed on the channel layer. The channel layer has different thicknesses respectively corresponding to the first drain/source and the second drain/source. The dielectric layer covers the substrate and exposes the first and the second drains. The first and the second pixel electrodes are disposed on the dielectric layer, and are electrically connected to the first and the second drains respectively.