IGZO TFT Oxygen Vacancy Passivation via Fluorine Treatment
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Solution Overview
Problem
Metal oxide semiconductors, such as zinc oxide and indium gallium zinc oxide, used in thin film transistors (TFTs) are prone to oxygen vacancies, leading to unstable TFTs and negative threshold voltages, which affect the stability and performance of the devices.
Innovation Solution
Treating the metal oxide layer with a fluorine containing gas or plasma to fill oxygen vacancies and prevent oxygen loss, thereby stabilizing the TFTs and eliminating negative threshold voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal oxide layer is used in TFT fabrication, then the device benefits from high carrier mobility, low processing temperature, and optical transparency, but the metal oxide layer is susceptible to oxygen vacancies that cause instability and negative threshold voltage
Solution Approach 1:
The patent applies preliminary action by performing fluorine treatment on the metal oxide layer before subsequent processing steps. The fluorine is introduced into the metal oxide layer in advance to fill oxygen vacancies and passivate the material, preventing instability and threshold voltage shifts before they affect device performance
Solution Approach 2:
The patent uses fluorine as an intermediary substance to resolve the contradiction. Fluorine atoms act as mediators that fill oxygen vacancies in the metal oxide layer, stabilizing the material without requiring changes to the fundamental metal oxide structure or composition
2Manufacturing precision
If oxygen vacancies are present in the metal oxide channel layer, then the TFT exhibits negative threshold voltage, but eliminating oxygen vacancies requires additional processing steps
Solution Approach 1:
The patent merges the fluorine treatment step with the existing metal oxide layer deposition and annealing process. By introducing fluorine during or after the metal oxide formation, the patent combines multiple functions (deposition, oxygen vacancy filling, and passivation) into an integrated process flow, minimizing additional complexity
Solution Approach 2:
The patent employs parameter changes by adjusting the fluorine introduction conditions (such as fluorine gas flow rate, treatment temperature, and treatment duration) to optimize oxygen vacancy filling while maintaining control over threshold voltage. This allows precise tuning of electrical properties through controlled parameter variation
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 fluorine treatment results in more stable TFTs with improved performance by reducing oxygen vacancies and preventing negative threshold voltages, enhancing the reliability and efficiency of the devices.
Implementation Method 1
The fluorine treatment of the metal oxide layer fills any oxygen vacancies in the metal oxide channel layer
Implementation Method 2
generating a first remote plasma, treating the metal oxide layer with first fluorine radicals
Implementation Method 3
treating the metal oxide layer with a fluorine containing gas or plasma
Data Source
AI summary
Embodiments of the present disclosure generally relate to methods for forming a TFT having a metal oxide layer. The method may include forming a metal oxide layer and treating the metal oxide layer with a fluorine containing gas or plasma. The fluorine treatment of the metal oxide layer helps fill the oxygen vacancies in the metal oxide channel layer, leading to a more stable TFT and preventing a negative threshold voltage in the TFT.