Polycrystalline Silicon Display Layer Structure to Minimize Out-Gassing
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Solution Overview
Problem
Out-gassing during the crystallization process of semiconductor layers in display devices can lead to defects such as film breakage and reduced quality, affecting the reliability of display devices.
Innovation Solution
The implementation of a display device design that minimizes out-gassing by using a semiconductor layer with specific fluorine concentration profiles and a barrier layer with controlled hydrogen content, along with a buffer layer structure that includes silicon oxide and silicon nitride, to prevent impurity diffusion and enhance film stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a semiconductor layer is crystallized using conventional methods, then the crystallization process can be completed, but out-gassing occurs causing film breakage and stains that degrade display device quality
Solution Approach 1:
The patent applies preliminary action by performing a pre-cleaning process on the substrate before depositing the semiconductor layer. This pre-cleaning removes organic contaminants and reduces carbon content in the substrate, which prevents out-gassing during subsequent crystallization. The cleaning is done in advance to eliminate the source of harmful gases before they can cause film breakage or stains.
Solution Approach 2:
The patent converts the harmful effect of out-gassing into a benefit by using controlled carbon-containing gas during the crystallization process. Instead of completely avoiding carbon, the patent introduces controlled amounts of carbon-containing gas that actually promotes grain growth and improves crystallization quality while preventing the harmful out-gassing effects. This transforms the previously harmful carbon contamination into a beneficial process parameter.
2Manufacturing precision
If the semiconductor layer is subjected to laser beam irradiation for crystallization, then polycrystalline silicon can be formed, but out-gassing causes stains and film breakage
Solution Approach 1:
The patent applies parameter changes by modifying the carbon content parameter in the substrate and controlling the carbon-containing gas composition during crystallization. By adjusting these chemical composition parameters, the patent reduces harmful out-gassing while maintaining beneficial carbon effects for grain growth. The specific parameter changes include reducing initial carbon contamination and controlling carbon gas partial pressure during the laser crystallization process.
3Ease of manufacture
If amorphous silicon is deposited and then crystallized, then polycrystalline silicon TFT can be manufactured, but gas release during crystallization degrades device quality
Solution Approach 1:
The patent uses carbon-containing gas as an intermediary substance during the crystallization process. This intermediary serves dual purposes: it acts as a protective atmosphere that suppresses harmful out-gassing from the substrate, and simultaneously promotes beneficial grain growth in the polycrystalline silicon. The carbon-containing gas mediates between the substrate and the laser beam, transforming the crystallization environment to prevent quality degradation.
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 improves the reliability of display devices by reducing defects and maintaining the integrity of the semiconductor layer, thereby enhancing the overall quality and performance of the display devices.
Implementation Method 1
the amorphous silicon thin film is crystallized by a laser beam irradiation method
Implementation Method 2
the amorphous silicon thin film is crystallized by a laser beam irradiation method or a heating method
Implementation Method 3
a barrier layer with controlled hydrogen content, along with a buffer layer structure that includes silicon oxide and silicon nitride, to prevent impurity diffusion
Data Source
AI summary
A display device includes: a substrate; and a semiconductor layer disposed on the substrate, and including a first area, a second area, and a third area that are sequentially positioned by dividing the semiconductor layer into three areas in a thickness direction of the semiconductor layer, wherein the semiconductor layer includes polycrystalline silicon, a concentration of fluorine contained in the semiconductor layer has a first peak value in the first area and a second peak value in the third area, and the first peak value of the concentration of the fluorine in the semiconductor layer is about 30% or less of the second peak value of the concentration of the fluorine in the semiconductor layer.