TFT Buffer Layer Composition for Low-Hydrogen Display Reliability
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Solution Overview
Problem
Conventional thin-film transistors with improved buffer layers face issues such as hydrogen pileup and increased electron traps, leading to pixel defects, leakage currents, and hot carrier phenomena due to high N—H bond content and Si—N—Si clusters in the buffer layer, which affect image display quality.
Innovation Solution
A thin-film transistor substrate with a buffer layer having an inorganic insulating material like silicon oxide or silicon nitride, where the area ratio of N—H bonds is 0.5% or less based on FTIR, and a content of 0.5 wt% or less, reducing hydrogen outgassing and Si—N—Si cluster defects, and employing a second barrier layer with a different material to minimize defects and improve film quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the buffer layer contains high N—H bond content to improve film quality, then the buffer layer provides better protection, but hydrogen pileup occurs causing pixel defects and leakage currents
Solution Approach 1:
The patent changes the chemical composition parameters of the buffer layer by controlling the N—H bond content to be 0.5 wt% or less, and adjusting the Si—N—Si cluster concentration to 7.0×10^17 spins/cm³ or less. This parameter optimization resolves the contradiction by maintaining protective film quality while eliminating harmful hydrogen pileup effects.
Solution Approach 2:
The patent employs a composite buffer layer structure combining inorganic insulating materials (such as silicon oxide and silicon nitride) with controlled N—H bond content. This composite approach provides both the protective quality needed for reliability and the defect reduction necessary to prevent hydrogen pileup and pixel defects.
2Reliability
If the buffer layer contains Si—N—Si clusters to improve insulating properties, then the insulating performance increases, but electron traps increase causing hot carrier phenomena
Solution Approach 1:
The patent optimizes the concentration parameter of Si—N—Si clusters in the buffer layer, limiting it to 7.0×10^17 spins/cm³ or less. This parameter control maintains the necessary insulating performance while preventing the formation of excessive electron traps that would cause hot carrier phenomena and device degradation.
3Object-generated harmful factors
If hydrogen outgassing is increased to remove trapped hydrogen, then hydrogen pileup is reduced, but image display quality deteriorates due to pixel defects and leakage currents
Solution Approach 1:
The patent applies preliminary action by pre-controlling the N—H bond content and Si—N—Si cluster concentration during buffer layer formation, rather than attempting to remove hydrogen after trapping occurs. This preventive approach eliminates hydrogen pileup at the source, maintaining both low defect levels and high image display quality without requiring aggressive outgassing treatments.
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 solution effectively suppresses hydrogen pileup, reduces defects, and minimizes outgassing, resulting in improved image display quality and reduced momentary afterimages by limiting N—H bond content and Si—N—Si clusters, thereby enhancing the performance and reliability of the display apparatus.
Implementation Method 1
an area ratio of a peak corresponding to an N—H bond in the material constituting the buffer layer is 0.5% or less based on a total peak area in a Fourier transform infrared spectroscopy (FTIR)
Implementation Method 2
effectively suppresses hydrogen pileup, reduces defects, and minimizes outgassing
Data Source
AI summary
Provided are a thin film transistor substrate which include a substrate, a buffer layer and a thin film transistor, a display apparatus including the thin film transistor substrate, and a method of manufacturing the display apparatus including the thin film transistor substrate. The buffer layer includes an inorganic insulating layer. An area ratio of a peak corresponding to an N—H bond in the buffer layer is 0.5% or less based on a total peak area in a Fourier transform infrared spectroscopy (FTIR).