Oxide Semiconductor Layer Anion Doping for Thermal Stability
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Solution Overview
Problem
Oxide semiconductor transistors with amorphous metal oxides, such as InZnO, face challenges in thermal stability during manufacturing processes due to metallization caused by heat treatment, which affects their mobility and on-current performance.
Innovation Solution
Incorporating specific anion elements like fluorine (F) and chlorine (Cl) into the metal oxide semiconductor layer within a controlled atomic percentage range (1-8%) enhances thermal stability and maintains high mobility by forming stable metal-oxygen bonds, reducing metallization and electron trap formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If amorphous metal oxide is used in oxide semiconductor transistor, then high mobility and large band gap are achieved, but thermal stability deteriorates due to metallization during heat treatment
Solution Approach 1:
The patent applies parameter changes by controlling the oxygen partial pressure during heat treatment within a specific range (1×10^-3 Pa to 100 Pa) and setting the heat treatment temperature between 200°C to 550°C. These parameter adjustments prevent metallization while maintaining high mobility, resolving the contradiction between speed (mobility) and stability (thermal stability).
Solution Approach 2:
The patent uses an inert atmosphere with controlled oxygen partial pressure during heat treatment to prevent unwanted oxidation and metallization of the amorphous metal oxide. This creates a stable environment that preserves both the high mobility characteristics and thermal stability of the oxide semiconductor layer.
2Ease of manufacture
If heat treatment is applied to oxide semiconductor transistor, then manufacturing process is completed, but metallization occurs reducing on-current performance
Solution Approach 1:
The patent changes the parameters of heat treatment by controlling oxygen partial pressure (1×10^-3 Pa to 100 Pa) and temperature (200°C to 550°C) to enable complete manufacturing processes without causing metallization. This allows ease of manufacture while preserving on-current performance and reliability.
Solution Approach 2:
The patent performs preliminary heat treatment under controlled oxygen partial pressure conditions before final device completion. This preliminary action prevents metallization from occurring during subsequent manufacturing steps, ensuring both ease of manufacture and maintained on-current performance.
3Temperature
If amorphous structure is used in metal oxide, then large band gap is achieved, but semiconductor characteristics deteriorate due to poor stability
Solution Approach 1:
The patent maintains the large band gap of amorphous metal oxide while improving semiconductor characteristics by controlling heat treatment parameters (oxygen partial pressure: 1×10^-3 Pa to 100 Pa, temperature: 200°C to 550°C). These parameter changes stabilize the amorphous structure, preventing metallization and maintaining reliable semiconductor characteristics.
Solution Approach 2:
The patent uses composite metal oxide materials containing multiple elements (In, Ga, Zn, Al, Ti, Si) in specific ratios to create an amorphous structure that maintains large band gap while achieving improved thermal stability and reliable semiconductor characteristics through synergistic effects of different metal elements.
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 thermal stability and maintains high mobility and on-current performance of oxide semiconductor transistors, even after heat treatment, while minimizing leakage current and ensuring reproducibility.
Implementation Method 1
Incorporating specific anion elements like fluorine (F) and chlorine (Cl) into the metal oxide semiconductor layer within a controlled atomic percentage range (1-8%) enhances thermal stability and maintains high mobility by forming stable metal-oxygen bonds
Data Source
AI summary
A semiconductor device of an embodiment includes an oxide semiconductor layer. The oxide semiconductor layer includes a metal oxide containing at least one first metal element selected from the group consisting of indium and tin and at least one second metal element selected from the group consisting of zinc, gallium, aluminum, tungsten, and silicon. The oxide semiconductor layer includes a first region in which at least one anion element selected from the group consisting of fluorine and chlorine is contained within a range of 1 atomic % or more and less than 8 atomic % in the metal oxide.