Lateral Crystallization of Semiconductor Layers Using Prism Sheet Segmentation
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Solution Overview
Problem
Existing methods for crystallizing semiconductor layers, such as excimer laser annealing, struggle to achieve uniform grain size greater than 0.5 μm and control grain size uniformity, making it difficult to manufacture semiconductor devices with high electron mobility and good electrical characteristics.
Innovation Solution
A method involving a prism sheet to split and direct laser beams onto a semiconductor layer, creating alternating areas for selective melting and lateral crystallization, using second areas as seeds to induce crystallization, allowing for easier control of crystallized areas and improved laser beam efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If excimer laser annealing is used to crystallize amorphous silicon, then the semiconductor layer can be crystallized, but the grain size is limited to less than 0.5 μm and uniformity is difficult to control
Solution Approach 1:
The laser beam is divided into multiple segments by the prism sheet, creating alternating irradiated and non-irradiated stripes on the semiconductor layer. This segmentation enables different regions to serve different functions: irradiated regions for melting and non-irradiated regions for serving as crystallization seeds, thereby achieving controlled lateral crystallization with uniform grain size
Solution Approach 2:
Different regions of the semiconductor layer are given different properties through selective laser irradiation. The irradiated areas receive high energy for complete melting while the non-irradiated areas remain as seed regions for crystallization. This local differentiation of quality enables precise control over crystallization behavior and grain size uniformity
2Manufacturing precision
If sequential lateral solidification or optical phase shift mask methods are used to increase grain size, then larger grain sizes can be achieved, but the apparatus complexity increases and it becomes difficult to apply to TFT process
Solution Approach 1:
A prism sheet is introduced as an intermediary optical element to divide the laser beam into multiple paths. This simple passive optical component replaces complex active control systems required by other lateral crystallization methods, achieving the same effect of creating alternating melt and seed regions without requiring sophisticated substrate positioning or multi-laser beam coordination
Solution Approach 2:
The mechanical complexity of precise substrate and multi-laser beam coordination in traditional lateral crystallization methods is replaced by an optical solution using a prism sheet. The beam splitting is achieved through optical refraction rather than mechanical positioning, significantly simplifying the apparatus while maintaining the ability to produce uniform large-grain crystallized layers
3Productivity
If conventional laser annealing is used, then the semiconductor layer can be crystallized, but the laser beam efficiency is low and the process is not cost-effective
Solution Approach 1:
The laser beam is segmented by the prism sheet to create multiple irradiated stripes across the semiconductor layer width. This allows simultaneous processing of multiple regions in a single pass, increasing the effective utilization of laser energy and reducing the total processing time compared to conventional single-beam annealing methods
Solution Approach 2:
The prism sheet configuration enables continuous laser beam propagation through the semiconductor layer with minimal loss. The optical paths are designed to maximize beam penetration and utilization, ensuring that laser energy is continuously and efficiently converted into thermal energy for crystallization throughout the processing area
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 enables the production of semiconductor devices with larger grain sizes, enhancing electron mobility and electrical characteristics, while simplifying the manufacturing process and improving laser beam utilization, leading to more efficient and cost-effective semiconductor device production.
Implementation Method 1
splitting the laser beams using a prism sheet comprising an array of a plurality of prisms
Implementation Method 2
irradiating a plurality of laser beams on the semiconductor layer
Implementation Method 3
fully melt the first areas
Implementation Method 4
inducing the first areas to be laterally crystallized using the second areas as seeds
Data Source
AI summary
Provided are a method of manufacturing a laterally crystallized semiconductor layer and a method of manufacturing a thin film transistor (TFT) using the method. The method of manufacturing the laterally crystallized semiconductor layer comprises: forming a semiconductor layer on a substrate; irradiating laser beams on the semiconductor layer; splitting the laser beams using a prism sheet comprising an array of a plurality of prisms, advancing the laser beams toward the semiconductor layer to alternately form first and second areas in the semiconductor layer so as to fully melt the first areas, wherein the laser beams are irradiated onto the first areas, and the laser beams are not irradiated onto the second areas; and inducing the first areas to be laterally crystallized using the second areas as seeds.