Amorphous Silicon TFT Grain Boundary Protrusion Control
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Solution Overview
Problem
In thin film transistors used in display apparatuses, protrusions formed at grain boundaries during crystallization can lead to excessive electric field concentration and visibility of unwanted patterns, causing instability and decreased product reliability.
Innovation Solution
A method involving surface cleaning of the amorphous silicon layer to remove the oxide film using a hydrogen fluoride solution, followed by a heat treatment with a laser beam, to control the height of protrusions at grain boundaries to 3 nanometers or less, and incorporating a buffer layer to enhance uniform heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is performed to crystallize the amorphous silicon layer, then the active layer is formed, but protrusions are formed at grain boundaries causing electric field concentration and device instability
Solution Approach 1:
The oxide film is removed from the amorphous silicon layer surface before heat treatment through hydrogen fluoride solution treatment. This preliminary action prevents the oxide film from causing excessive protrusion formation during subsequent crystallization, thereby controlling protrusion height and preventing electric field concentration that would lead to device instability
Solution Approach 2:
The patent controls the concentration of hydrogen fluoride solution (0.1-10 vol%) and treatment conditions to achieve optimal oxide film removal. By adjusting these parameters, the protrusion height is controlled to be 5 nm or less, preventing both excessive protrusion formation and complete oxide removal that would damage the silicon layer
2Manufacturing precision
If the oxide film is completely removed to reduce protrusion size, then electric field concentration is reduced, but the silicon layer may be damaged
Solution Approach 1:
The patent optimizes the hydrogen fluoride solution concentration (0.1-10 vol%) and treatment conditions to achieve selective oxide film removal. This parameter control ensures sufficient oxide removal to limit protrusions to 5 nm or less while maintaining the structural integrity of the underlying amorphous silicon layer
Solution Approach 2:
The hydrogen fluoride solution acts as an intermediary that selectively removes the oxide film without directly attacking the silicon layer. The controlled chemical reaction between HF and the oxide film allows precise control over removal depth, preventing silicon layer damage while achieving the desired protrusion height reduction
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 reduces electrical deviations and minimizes the visibility of patterns, enhancing the stability and quality of the thin film transistor and display apparatus by maintaining the protrusion height at 3 nanometers or less, thereby improving product reliability.
Implementation Method 1
removing an oxide film on a surface of the amorphous silicon layer by performing a surface cleaning, wherein the removing the oxide film includes spraying a hydrogen fluoride solution onto the surface of the amorphous silicon layer
Implementation Method 2
forming an active layer by performing a heat treatment on the amorphous silicon layer, wherein the amorphous silicon layer is changed into crystalline silicon by the heat treatment
Implementation Method 3
the amorphous silicon layer is changed into crystalline silicon by the heat treatment
Data Source
AI summary
A method of manufacturing a thin film transistor includes: removing an oxide film on a surface of an amorphous silicon layer by performing a surface cleaning; and forming an active layer by performing a heat treatment on the amorphous silicon layer, where the amorphous silicon layer is changed into crystalline silicon by the heat treatment.