Microcrystalline Silicon Thin Film Transistor Process
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional amorphous silicon thin film transistors in liquid crystal displays have limited electron mobility and stability, restricting the performance of electronic devices in terms of resolution, efficiency, and reliability.
Innovation Solution
A method for forming microcrystalline silicon layers with a high crystalline fraction and controlled process pressures to enhance electron mobility and stability, involving a gas mixture with a high hydrogen-to-silane ratio and adjusting pressures during plasma deposition in a processing chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional amorphous silicon is used in thin film transistors, then the manufacturing process is simple, but electron mobility is limited
Solution Approach 1:
The patent changes the crystalline structure parameter of the silicon layer from amorphous to microcrystalline, and adjusts deposition parameters (pressure, gas ratios, temperature) to achieve high electron mobility while maintaining manufacturing feasibility through plasma-enhanced chemical vapor deposition
Solution Approach 2:
The patent creates a composite structure with a microcrystalline silicon layer having a specific grain structure and orientation relationships, combining crystalline regions with controlled grain boundaries to achieve both high electron mobility and manufacturing practicality
2Ease of manufacture
If conventional amorphous silicon is used, then device fabrication is straightforward, but device stability is poor
Solution Approach 1:
The patent changes the material composition parameter by forming a microcrystalline silicon layer with specific crystallographic orientation relationships and grain structure, which inherently provides better stability while maintaining fabrication simplicity through controlled deposition processes
Solution Approach 2:
Instead of trying to improve amorphous silicon stability through complex post-processing, the patent inverts the approach by directly depositing microcrystalline silicon with stable crystal structures, achieving stability as a inherent property of the deposited layer
3Reliability
If higher electron mobility is achieved through material improvement, then pixel area for light transmission increases, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes deposition parameters (pressure, gas flow ratios, substrate temperature) to achieve high electron mobility microcrystalline silicon layers in a single deposition process, avoiding the need for multiple processing steps and reducing manufacturing complexity
Solution Approach 2:
The patent performs preliminary optimization of the deposition process to directly form the desired microcrystalline structure with high electron mobility in one step, eliminating the need for subsequent complex processing steps to achieve the same result
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 method results in microcrystalline silicon layers with improved electron mobility and stability, reducing film leakage and enhancing the electrical performance of transistor and diode devices.
Implementation Method 1
maintaining a first process pressure greater than about 6 Torr in the processing chamber to deposit a first microcrystalline silicon containing layer in presence of a plasma formed from the first gas mixture
Implementation Method 2
supplying a first gas mixture having a hydrogen containing gas to a silicon containing gas flow rate ratio greater than about 200:1 into the processing chamber
Data Source
AI summary
Methods for forming a microcrystalline silicon layer in a thin film transistor structure are provided. In one embodiment, a method for forming a microcrystalline silicon layer includes providing a substrate in a processing chamber, supplying a first gas mixture having a hydrogen containing gas to a silicon containing gas flow rate ratio greater than about 200:1 into the processing chamber, maintaining a first process pressure greater than about 6 Torr in the processing chamber to deposit a first microcrystalline silicon containing layer in presence of a plasma formed from the first gas mixture, supplying a second gas mixture into the processing chamber, and maintaining a second process pressure less than about 5 Torr in the processing chamber to deposit a second microcrystalline silicon containing layer in presence of a plasma formed from the second gas mixture.