Heat Treatment Apparatus for Polycrystalline Silicon Substrate Flatness
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Solution Overview
Problem
Conventional heat treatment processes for forming polycrystalline silicon layers in thin film transistors, such as those used in flat panel displays, often result in substrate deformation and thermal damage, leading to unacceptable flatness and rendering subsequent processes impossible.
Innovation Solution
A heat treatment apparatus and method that uses a support plate and transfer unit to maintain substrate flatness by moving the substrate through a chamber with a heater, employing crystallization techniques like super grain silicon to convert amorphous silicon into polycrystalline silicon while minimizing thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional heat treatment process is used to crystallize amorphous silicon into polycrystalline silicon, then the crystallization is achieved, but substrate deformation and thermal damage occur leading to unacceptable flatness
Solution Approach 1:
A support plate is introduced as an intermediary component between the heating apparatus and the device substrate. The support plate absorbs and distributes thermal stress, preventing direct thermal damage to the substrate while maintaining the necessary heat treatment conditions for crystallization. This mediator approach resolves the contradiction by isolating the substrate from harmful thermal effects while still achieving the desired crystallization.
Solution Approach 2:
The heating rate and temperature parameters are optimized and controlled during the heat treatment process. By implementing a controlled heating rate and maintaining precise temperature parameters, the substrate experiences minimal thermal stress and deformation while still achieving complete crystallization of the amorphous silicon layer. This parameter optimization resolves the contradiction between achieving crystallization and preventing thermal damage.
2Reliability
If high temperature heat treatment is applied to crystallize the amorphous silicon layer, then electron mobility is improved, but substrate flatness deteriorates
Solution Approach 1:
The support plate serves as a thermal mediator that enables high-temperature heat treatment to achieve the necessary electron mobility in the polycrystalline silicon layer while preventing excessive thermal stress that would cause substrate deformation. The support plate maintains substrate flatness even at high temperatures required for improving electron mobility.
Solution Approach 2:
The heating rate is carefully controlled and optimized to achieve complete crystallization and high electron mobility while minimizing thermal stress on the substrate. By implementing precise temperature parameter control, the process achieves the necessary electron mobility improvement without causing unacceptable substrate flatness deterioration.
3Productivity
If fast heating rate is used to reduce processing time, then productivity is improved, but thermal stress and substrate deformation increase
Solution Approach 1:
The heating rate parameter is optimized to achieve an efficient balance between processing time and thermal stress generation. By implementing a controlled but efficient heating rate, the process achieves acceptable processing time while minimizing thermal stress and substrate deformation. The support plate further assists in distributing thermal stress during this optimized heating process.
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 apparatus effectively crystallizes amorphous silicon into polycrystalline silicon with reduced substrate deformation, maintaining flatness within acceptable limits, allowing for subsequent processing steps and improving the reliability of the heat treatment process.
Implementation Method 1
a heater positioned in the chamber, the heater being configured to heat the device substrate while the device substrate is located in the chamber
Implementation Method 2
heat-treating the device substrate may comprise crystallizing the amorphous silicon layer into a polycrystalline silicon layer
Data Source
AI summary
A heat treatment apparatus and a heat treatment method using the same are disclosed. In the method, a support plate on which a device substrate is mounted is loaded into the heat treatment apparatus using a transfer unit in an in-line manner, and the device substrate mounted on the support plate is heat-treated using the heat treatment apparatus.