Transflective LCD Fabrication Using Vertical Electrode Stacking
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Solution Overview
Problem
Transflective liquid crystal displays (LCDs) face challenges in reducing the number of masking processes, which increases production costs and can lead to wavy noise due to protrusive active patterns and reduced aperture ratios, limiting their picture quality and luminance.
Innovation Solution
A method for fabricating a transflective LCD that reduces the number of masking processes to five by forming a gate electrode and active pattern as an island, using a half-tone mask to pattern source and drain electrodes, and forming pixel electrodes of transparent conductive film below the data lines, avoiding adhesion issues and signal interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of masking processes is reduced to simplify fabrication, then productivity and ease of manufacture improve, but manufacturing precision deteriorates due to protrusive active patterns causing wavy noise
Solution Approach 1:
The patent introduces a vertical dimensional relationship by forming the active pattern at a lower level than the data line, creating a stepped structure. This dimensional separation allows the active pattern to be positioned underneath the data line, preventing protrusion and eliminating wavy noise while maintaining reduced masking process benefits
Solution Approach 2:
The patent segments the pixel region into distinct functional zones: a transmissive region with pixel electrodes and a reflective region with reflective electrodes. This segmentation allows different light handling mechanisms to coexist without interference, improving both manufacturing simplicity and picture quality
2Ease of manufacture
If the number of masking processes is reduced, then ease of manufacture improves, but aperture ratio increases due to improper electrode positioning
Solution Approach 1:
By positioning pixel electrodes below the data line in a vertical arrangement, the patent maximizes the horizontal aperture area without compromising electrical connectivity. The data line passes over the pixel electrode region, allowing both components to occupy different spatial layers and thus increasing the effective aperture ratio
3Reliability
If pixel electrodes are formed below data lines, then adhesion issues are eliminated, but device complexity increases due to multi-layer structure
Solution Approach 1:
The patent resolves adhesion issues by separating pixel electrodes and data lines into different vertical layers, eliminating direct contact and potential adhesion problems between incompatible materials. The insulating film between layers provides electrical isolation while the stepped configuration maintains structural integrity without requiring complex additional components
Data Source
AI summary
A transflective liquid crystal display includes: a first substrate divided into a pixel part and first and second pad parts; a gate electrode and a gate line formed at the pixel part of the first substrate; a first insulation film formed on the first substrate; an active pattern formed as an island at an upper portion of the gate electrode and having a width smaller than the gate electrode; an ohmic-contact layer and a barrier metal layer formed on the first substrate and on source and drain regions of the active pattern; source and drain electrodes formed at the pixel part of the first substrate and electrically connected with the source and drain regions of the active pattern via the ohmic-contact layer and the barrier metal layer; a data line formed at the pixel part of the first substrate and crossing the gate line to define a pixel region including a reflective portion and a transmissive portion; a pixel electrode formed at the transmissive portion of the pixel region and electrically connected with the drain electrode; a source electrode pattern, a drain electrode pattern and a data line pattern formed at lower portions of the source electrode, the drain electrode and the data line, and formed of a conductive film that forms the pixel electrode; a reflective electrode formed at the reflective portion of the pixel region and electrically connected with the drain electrode and the pixel electrode; a second insulation film exposing the pixel electrode of the pixel region; and a second substrate attached to the first substrate in a facing manner.