Aluminum Metal Layer Segmentation in LTPS Array Substrates
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Solution Overview
Problem
The high resistance of Molybdenum (Mo) metal used in traditional Low Temperature Poly-silicon (LTPS) array substrates leads to significant RC delay in signal wires, affecting the reliability and scalability of image displays.
Innovation Solution
The use of aluminum as the second metal layer in the manufacturing method for array substrates, where a Poly-Silicon layer is formed on a glass substrate with heavily doped regions, and aluminum is used for both the first and second metal layers, reducing RC delay and enabling larger product sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If Molybdenum (Mo) metal is used for the first metal layer to ensure thermostability during high-temperature activation process, then the activation process can be performed at high temperature to achieve ohmic contact, but the resistance of the metal layer becomes very high causing serious RC delay
Solution Approach 1:
The metal layer is divided into two separate layers: the first metal layer (Mo) deposited before activation to provide thermostability during high-temperature processing, and the second metal layer (Al) deposited after activation to provide low resistance for signal transmission. This segmentation allows each layer to fulfill its specific function without compromise.
Solution Approach 2:
The first metal layer is deposited preliminarily before the activation process to ensure thermostability during the high-temperature activation. After activation is completed, the second metal layer is then deposited to replace the high-resistance Mo for signal wire functions.
2Stability of the object's composition
If Molybdenum (Mo) metal is used as the first metal layer, then thermostability is achieved for high-temperature activation, but the high resistance prevents it from being used as conductive metal material for large-sized products
Solution Approach 1:
The metal structure is segmented into two functional layers: Mo layer for thermostability during processing, and Al layer for low-resistance conduction in large-sized products. This allows the product to be manufactured at high temperature while maintaining good electrical performance in the final large-scale product.
Solution Approach 2:
The material parameter (metal type) is changed at different stages of the process. Mo is used during the high-temperature activation stage, then Al is introduced for the conduction stage. This parameter change allows optimization for both processing conditions and final product performance.
3Manufacturing precision
If the first metal layer is deposited before activation process, then the activation can be performed at high temperature to form ohmic contact, but the high resistance of Mo causes serious RC delay affecting image display reliability
Solution Approach 1:
The metal layer is segmented into two parts with different functions: the first Mo layer enables precise ohmic contact formation through high-temperature activation, while the second Al layer ensures low resistance for reliable image display by replacing the high-resistance Mo for signal transmission.
Solution Approach 2:
The first Mo layer acts as an intermediary during the activation process, enabling ohmic contact formation at high temperature. After this intermediate step is completed, it is replaced by the second Al layer for the final low-resistance conduction function.
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
The implementation of aluminum metal layers reduces RC delay and enhances the reliability of display panels, facilitating the production of larger-sized LTPS displays by lowering resistivity and optimizing the manufacturing process.
Implementation Method 1
forming heavily doped regions by performing heavily doping and activation process at both sides of the Poly-Silicon layer
Implementation Method 2
the resistance for metal Mo is very high to be applied as a conductive metal material, and the RC delay is occurred seriously
Data Source
AI summary
A manufacturing method for an array substrate is provided in the present invention. The method comprises: forming a Poly-Silicon layer on a glass substrate; forming heavily doped regions by performing heavily doping and activation process at both sides of the Poly-Silicon layer; forming a source/a drain of a first metal layer growing on the heavily doped region; forming a gate of both a gate insulator and a second metal layer growing sequentially on the Poly-Silicon layer, wherein, a material of the second metal layer is aluminum. The activation technology process can be improved in the present invention to reduce RC delay in metal wires of product and then further to achieve large sizes for products.