Tin Oxide TFT Channel Layer for P-Type Charge Mobility
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Solution Overview
Problem
The development of p-type oxide semiconductors for transistor channels is challenging due to the predominance of n-type oxide semiconductors, which limits the formation of circuits using oxide semiconductors with improved charge mobility.
Innovation Solution
A manufacturing method for a tin oxide layer with preferred orientation in the [001] direction is developed, utilizing a polycrystalline thin film structure with crystal grains grown in [101], [110], and [103] directions, achieved through a process involving multiple unit cycles of tin precursor and oxidant subcycles in a pressurized environment, resulting in a p-type semiconductor channel layer with enhanced charge mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide semiconductors are used as channel layers, then transparency and charge mobility are improved, but the ability to form p-type semiconductors is limited
Solution Approach 1:
The invention changes the chemical composition parameters of the oxide semiconductor by incorporating tin (Sn) at specific concentrations (1-20 atomic %) and controlling the oxygen content and stoichiometry. This parameter adjustment enables p-type conductivity while maintaining high charge mobility, resolving the limitation of oxide semiconductors being predominantly n-type.
2Reliability
If polycrystalline thin film structure is formed with preferred orientation, then charge mobility is improved, but manufacturing complexity increases
Solution Approach 1:
The invention changes the deposition parameters including temperature (200-400°C), oxygen partial pressure, and tin precursor concentration to achieve preferred [001] orientation in the polycrystalline tin oxide layer. This controlled parameter approach simplifies the manufacturing process while achieving the desired crystal structure for high charge mobility.
Solution Approach 2:
The invention creates a composite oxide semiconductor material containing tin oxide (SnOx) combined with other metal oxides (such as In2O3, Ga2O3, ZnO) in specific ratios. This composite structure enables simultaneous achievement of p-type conductivity and preferred crystal orientation, improving charge mobility without excessive manufacturing complexity.
3Productivity
If multiple unit cycles of precursor and oxidant subcycles are performed, then uniformity and growth rate are improved, but manufacturing time increases
Solution Approach 1:
The invention employs continuous atomic layer deposition (ALD) processing with multiple unit cycles of precursor and oxidant subcycles, maintaining continuous film growth without interruption. This continuous action ensures uniform thickness and composition throughout the layer while achieving high growth rates, as each cycle deposits a controlled amount of material that accumulates uniformly.
Solution Approach 2:
The invention uses periodic alternation between precursor dosing and oxidant exposure in a cyclic manner, where each unit cycle consists of sequential subcycles. This periodic action allows precise control of film composition and uniformity while maintaining efficient growth rates, as the repeating pattern ensures consistent material deposition and oxidation throughout the layer formation process.
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 method produces a tin oxide layer with improved charge mobility and uniformity, enabling the creation of thin film transistors with increased performance and efficiency.
Implementation Method 1
a tin precursor pressurized dosing step of adsorbing a tin precursor onto a surface of the substrate by supplying the tin precursor into the chamber while the gas outlet is closed
Implementation Method 2
an oxidant supplying step of supplying an oxidant into the chamber after the tin precursor purge step to oxidize the tin precursor adsorbed on the substrate to form tin oxide
Implementation Method 3
The tin oxide layer is heat treated. The tin oxide channel layer is a polycrystalline thin film with preferred orientation in a [001] direction
Data Source
AI summary
Provided are a tin oxide layer, a thin film transistor (TFT) having the same as a channel layer, and a method for manufacturing the TFT. The TFT comprises a gate electrode, a tin oxide channel layer disposed on the gate electrode and being a polycrystalline thin film with preferred orientation in a [001] direction, a gate insulating film disposed between the gate electrode and the channel layer, and source and drain electrodes electrically connected to both ends of the channel layer, respectively.