Amorphous Silicon Crystallization via Inclined Laser Scanning
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Solution Overview
Problem
The existing crystallization methods for amorphous silicon layers, such as sequential lateral solidification, often result in uncrystallized regions and display defects like moiré patterns and oblique stains due to the use of masks and fixed laser angles, which compromise image quality and efficiency.
Innovation Solution
A method involving a laser beam with an inclined angle relative to the substrate, moved in both perpendicular directions to ensure complete crystallization without a pattern mask, using a relative movement velocity equation to optimize coverage and prevent uncrystallized areas, thereby improving crystallization characteristics and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed laser beam angle and mask are used in sequential lateral solidification, then the crystallization process can be simplified, but uncrystallized regions and display defects like moiré patterns and oblique stains occur
Solution Approach 1:
The patent applies dynamics by making the laser beam angle adjustable rather than fixed. The laser beam is irradiated at an inclined angle θ that can be optimized to prevent uncrystallized regions while maintaining process simplicity. This dynamic adjustment of the laser angle resolves the contradiction between ease of manufacture and manufacturing precision.
Solution Approach 2:
The patent changes the parameter of laser beam angle from a fixed value to an optimized inclined angle θ. By adjusting this parameter, the method achieves complete crystallization coverage without creating uncrystallized regions, thereby improving manufacturing precision while keeping the process relatively simple.
2Manufacturing precision
If a pattern mask is used in sequential lateral solidification, then crystallization coverage can be controlled, but manufacturing complexity and costs increase
Solution Approach 1:
The patent extracts and eliminates the pattern mask from the sequential lateral solidification process. By using an optimized inclined laser angle instead of a mask, the method achieves crystallization coverage control without the added complexity and costs of mask fabrication and alignment.
Solution Approach 2:
The patent replaces the mechanical mask system with an optical parameter adjustment (laser angle θ). This substitution eliminates the need for physical masks while maintaining precise control over crystallization coverage, thereby reducing device complexity.
3Productivity
If the laser beam is moved only in one direction, then the process is simpler, but uncrystallized regions remain and crystallization efficiency is reduced
Solution Approach 1:
The patent adds a second dimension to laser beam movement by moving it not only in the scanning direction but also in the vertical direction. This two-dimensional movement pattern ensures complete coverage of the amorphous silicon layer, eliminating uncrystallized regions and improving crystallization efficiency without excessive complexity.
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 effectively minimizes display defects and enhances crystallization efficiency by ensuring complete coverage of the amorphous silicon layer without uncrystallized regions, while simplifying the process and reducing manufacturing costs by eliminating the need for pattern masks.
Implementation Method 1
irradiating a laser beam onto the substrate so as to have an inclined angle with respect to the first and second sides of the substrate
Implementation Method 2
crystallization method of an amorphous silicon layer by laser irradiation
Data Source
AI summary
A crystallization method is disclosed. In one embodiment, the method includes providing a substrate having an amorphous silicon layer, wherein the substate has first and second sides opposing each other and irradiating a laser beam onto the substrate so as to have an inclined angle with respect to the first and second sides of the substrate. The method further includes relatively moving one of the laser beam and the substate with respect to the other i) in a first direction from the first side to the second side of the substate and ii) in a second direction which crosses the first direction.