TFT Substrate Manufacturing via Segmented Crystallization
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Solution Overview
Problem
Current LTPS TFT substrate manufacturing methods using Excimer Laser Annealing (ELA) technology face challenges in achieving uniform lattice and crystal orientation, leading to non-uniform images and high electric leakage in AMOLED displays.
Innovation Solution
A method involving a dual approach for manufacturing TFT substrates, where Excimer Laser Annealing is used for the drive TFT region to achieve LTPS and Solid Phase Crystallization for the display TFT region, allowing for different performance requirements to be met, resulting in improved luminous uniformity and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Excimer Laser Annealing (ELA) technology is used to prepare polysilicon, then the manufacturing process can be completed, but lattice uniformity and crystal orientation cannot be controlled effectively, leading to non-uniform images and high electric leakage
Solution Approach 1:
The substrate is divided into multiple regions (first region and second region), and different crystallization methods are applied to different regions. The first region uses ELA method while the second region uses SPC method, allowing each region to be optimized independently for its specific functional requirements.
Solution Approach 2:
Different crystallization methods are selected for different regions based on their specific functional requirements. The drive TFT region uses ELA for high-speed switching, while the display TFT region uses SPC for uniformity and low leakage, achieving local optimization of material properties.
2Productivity
If ELA method is used for polysilicon preparation, then manufacturing can proceed, but the polysilicon cannot be formed uniformly on the whole substrate
Solution Approach 1:
The substrate is segmented into different regions with different crystallization methods. The SPC region provides uniform polysilicon formation, while the ELA region provides high-speed performance, resolving the contradiction between manufacturing capability and uniformity.
Solution Approach 2:
The patent creates a composite structure where different polysilicon types (ELA-prepared and SPC-prepared) coexist on the same substrate, each contributing their advantageous properties to the overall device performance.
3Ease of manufacture
If a single crystallization method is used for the entire substrate, then the manufacturing process is simple, but it cannot meet different performance requirements of drive TFT and display TFT regions
Solution Approach 1:
The manufacturing process is segmented into different crystallization steps for different regions. This allows the process to be tailored to meet the specific performance requirements of each region while maintaining a systematic manufacturing approach.
Solution Approach 2:
Different crystallization methods are applied to different regions based on their specific functional requirements. The drive TFT region requires high-speed switching characteristics from ELA, while the display TFT region requires uniformity and low leakage from SPC.
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 enhances luminous uniformity and reduces power consumption by utilizing LTPS for quick response in the display region and SPC poly TFT for constant current in the drive region, addressing non-uniformity and leakage issues while maintaining manufacturing cost-effectiveness.
Implementation Method 1
subjecting the first amorphous silicon layer to an excimer laser annealing scan (ELA scan) treatment, to convert the first amorphous silicon layer into a first polysilicon layer
Implementation Method 2
instantaneous pulse of a laser irradiates on the surface of the amorphous silicon, so that the amorphous silicon can be melted and recrystallized
Implementation Method 3
conducting solid phase crystallization (SPC) of the second amorphous silicon layer, to convert crystal of the second amorphous silicon layer into a second polysilicon layer
Implementation Method 4
implanting ions into the gate insulating layer, the first gate electrode and the second gate electrode being used as blocking layer
Data Source
AI summary
A method for manufacturing a TFT substrate is disclosed. The TFT substrate includes a drive TFT region and a display TFT region. The drive TFT region and the display TFT region are manufactured with different technologies, so that different requirements for TFT can be met. The manufacturing method according to the present disclosure mainly includes: forming a first amorphous silicon layer to obtain a drive TFT region; forming a second amorphous silicon layer to obtain a display TFT region; and then depositing a passivation layer and a flat layer, so that the TFT substrate is manufactured after following treatment steps.