Poly Silicon Pattern With Multi-Directional Grains For LCD Switching Elements
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Solution Overview
Problem
The current poly silicon LCD devices face limitations in current mobility and design margin due to the restricted orientation of poly silicon grains formed through sequential lateral solidification, which fixes the extended direction of grains, thereby deteriorating the TFT location and design flexibility.
Innovation Solution
The array substrate is designed with a poly silicon pattern having blocks with grains extended in multiple directions, including both horizontal and longitudinal orientations, allowing for improved current mobility and design margin by forming a poly silicon layer with alternating grain regions using a mask with transmitting and blocking portions to control laser irradiation and grain growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the poly silicon grain extended direction is fixed through mask design, then current mobility is improved in that direction, but the TFT location and design margin are restricted
Solution Approach 1:
The mask is divided into multiple blocks (first block, second block, third block, fourth block) with different transmitting and blocking portions arranged in specific patterns. Each block creates grains extended in different directions, allowing the poly silicon layer to have multi-directional grain structures that improve both current mobility and design flexibility.
Solution Approach 2:
The mask blocks are designed with asymmetric transmitting and blocking portion arrangements, where each block has a unique configuration that directs grain growth in specific orientations. This asymmetric design enables control over grain direction while maintaining flexibility in TFT placement.
2Manufacturing precision
If the mask transmitting and blocking portions are extended in a single direction, then poly silicon grains are extended uniformly, but the channel direction of TFT becomes restricted
Solution Approach 1:
The mask is segmented into multiple blocks with different orientations. The first and third blocks have transmitting portions extending in a first direction, while the second and fourth blocks have transmitting portions extending in a second direction perpendicular to the first direction. This segmentation creates uniform grain extension within each block while providing overall directional diversity.
Solution Approach 2:
The invention transitions from single-direction grain extension to multi-directional grain extension by adding another dimension (perpendicular direction) to the grain growth patterns. This allows TFT channels to be oriented in different directions without compromising grain uniformity within each directional region.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances current mobility and design margin of the switching element by allowing channels to be extended in either direction, increasing the channel width and flexibility, thereby improving the performance of the TFTs in LCD devices.
Implementation Method 1
A laser beam is irradiated on a first melting area of an amorphous silicon layer to melt the first melting area so that a poly silicon grain grows from an interface between the first melting area and a non-melting area toward an interior of the first melting area
Data Source
AI summary
An array substrate includes a base substrate, a switching element, and a pixel electrode. The switching element is on the base substrate. The switching element includes a poly silicon pattern having at least one block. Grains are formed in each of the at least one block that are extended in a plurality of directions. The pixel electrode is electrically connected to the switching element. Therefore, current mobility and design margin of the switching element are improved.