Display Device with Stepped Metal for Polysilicon Electron Mobility
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Solution Overview
Problem
Existing excimer laser annealing processes struggle to consistently achieve high electron mobility in low-temperature polysilicon due to irregular silicon particle arrangements, which affect the performance of thin-film transistors in display devices.
Innovation Solution
The process involves forming an inclined surface in the semiconductor layer using a stepped lower metal layer, allowing controlled interference of laser light to enhance the regularity of silicon particles through excimer laser annealing, thereby improving electron mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional excimer laser annealing is applied to amorphous silicon, then the silicon can be converted to low-temperature polysilicon, but the silicon particles remain irregularly arranged resulting in limited electron mobility
Solution Approach 1:
The patent applies preliminary action by forming an inclined surface on the semiconductor layer before laser annealing. This pre-structuring step creates controlled interference patterns during subsequent laser irradiation, which guides the formation of regular silicon particle arrangements and improves electron mobility in the resulting low-temperature polysilicon
Solution Approach 2:
The patent utilizes curvature by creating an inclined surface (curved/angled geometry) on the semiconductor layer. This curved surface structure enables controlled interference of laser light during annealing, transforming the irregular amorphous silicon into low-temperature polysilicon with regular particle arrangements and enhanced electron mobility
2Productivity
If high electron mobility is achieved through laser annealing, then display performance improves, but the process requires precise control of silicon particle regularity which is difficult to achieve
Solution Approach 1:
The inclined surface is formed in advance before laser annealing, providing a predetermined structure that automatically generates controlled interference patterns during laser irradiation. This preliminary structuring simplifies the manufacturing process by eliminating the need for complex real-time control of silicon particle arrangements, making high electron mobility more easily achievable
Solution Approach 2:
The inclined surface acts as an intermediary element between the laser beam and the amorphous silicon. It mediates the laser-silicon interaction by creating controlled interference patterns that guide the phase transition and crystallization process, thereby simplifying the overall manufacturing control while achieving high electron mobility
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 method results in improved electron mobility in low-temperature polysilicon, facilitating high-resolution, slim-bezel, and low-power consumption displays by ensuring regular silicon particle arrangements.
Implementation Method 1
irradiating a laser simultaneously to a flat surface and an inclined surface of the semiconductor layer
Implementation Method 2
excimer laser annealing process is used to convert amorphous silicon of thin-film transistors into low-temperature polysilicon
Implementation Method 3
allowing controlled interference of laser light to enhance the regularity of silicon particles through excimer laser annealing
Data Source
AI summary
A display device includes a first barrier layer disposed on a substrate, a lower metal layer disposed on the first barrier layer, and a semiconductor layer disposed on the lower metal layer. In a cross-sectional view, the lower metal layer includes a first part spaced apart from the semiconductor layer and a second part closer to the semiconductor layer, in a plan view, an area of the second part is smaller than an area of the first part, and a side of the semiconductor layer and a side of the second part, which is adjacent to the semiconductor layer, are parallel to each other.