Nickel Disilicide Seed Layer for LTPS Crystallization
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Solution Overview
Problem
Existing methods for manufacturing low-temperature polysilicon thin film transistors (LTPS TFTs) face challenges such as high cost and uneven grain distribution with excimer laser annealing, and residual metal issues with metal-induced crystallization, leading to performance deterioration and increased leakage current.
Innovation Solution
A method involving the use of a nickel disilicide metal seed layer for metal-induced crystallization, where the metal seed layer is deposited after patterning the amorphous silicon layer, reducing the area of the amorphous silicon layer and shortening annealing time, and diffusing only the necessary metal atoms to minimize residual metal and enhance grain growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If metal-induced crystallization is used to crystallize amorphous silicon, then crystallization temperature is reduced, but residual metal remains in the thin film transistor resulting in large leakage current
Solution Approach 1:
The patent extracts and removes the metal catalyst layer after it has fulfilled its crystallization function. The method involves forming a metal layer for induced crystallization, then selectively removing it through wet etching or other methods, thereby eliminating residual metal that causes leakage current while maintaining the low-temperature crystallization benefit
Solution Approach 2:
The patent applies local quality by using a metal layer only in the regions where crystallization is needed, and removes it from the channel region. The metal layer is formed selectively and removed selectively, ensuring that residual metal does not remain in critical areas where it would affect device performance
2Productivity
If excimer laser annealing is used to crystallize amorphous silicon, then crystallization speed is improved, but cost increases and grain distribution becomes uneven
Solution Approach 1:
The patent replaces the expensive excimer laser annealing system with a simpler thermal annealing process using a metal-induced crystallization mechanism. The metal layer acts as a catalyst that enables crystallization at lower temperatures and with simpler equipment, thereby reducing manufacturing cost while maintaining reasonable crystallization speed
Solution Approach 2:
The patent introduces a metal layer as an intermediary substance that facilitates the crystallization process. This metal layer acts as a catalyst that enables amorphous silicon to crystallize at lower temperatures and with more uniform grain distribution, replacing the need for expensive laser annealing equipment
3Reliability
If solid-phase crystallization is used to crystallize amorphous silicon, then crystallization is achieved, but heating at high temperature for long time causes phase transition of glass substrate and reduces production efficiency
Solution Approach 1:
The patent changes the temperature parameter by using metal-induced crystallization that enables crystallization at lower temperatures (below the glass substrate transition temperature). This parameter change allows crystallization to proceed without causing substrate phase transition, and the metal catalyst accelerates the process to reduce annealing time
Solution Approach 2:
The metal layer serves as an intermediary that enables crystallization to proceed rapidly at lower temperatures. It facilitates the phase transition of silicon without requiring high-temperature prolonged heating, thus preventing glass substrate damage and reducing production time loss
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 reduces residual metal, improves transistor performance by increasing grain size, and shortens crystallization annealing time, resulting in a more efficient and stable LTPS TFT production process.
Implementation Method 1
converting the amorphous silicon layer into a polysilicon layer under an induction effect of the metal seed layer
Implementation Method 2
through an annealing treatment
Implementation Method 3
diffusing only the necessary metal atoms to minimize residual metal
Data Source
AI summary
This application discloses a method for manufacturing a thin film transistor, and a display panel. The method for manufacturing a thin film transistor includes steps of providing a substrate; forming an amorphous silicon thin film layer on the substrate; patterning the amorphous silicon thin film layer to form an amorphous silicon layer; forming a metal seed layer made of a nickel disilicide (NiSi2) material on the amorphous silicon layer; converting the amorphous silicon layer into a polysilicon layer under an induction effect of the metal seed layer and through an annealing treatment; and forming a source and drain layer.