Oxide Semiconductor TFT Purification for Stable Electric Characteristics
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Solution Overview
Problem
Existing semiconductor devices with oxide semiconductor thin film transistors face instability due to impurities such as moisture, which affect the reliability and electric characteristics of the transistors.
Innovation Solution
A manufacturing method involving heat treatment in an oxygen atmosphere to dehydrate and dehydrogenate the oxide semiconductor layer, followed by slow cooling and the formation of an oxide insulating layer to reduce impurities and improve the transistor's reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is performed in an oxygen atmosphere to remove impurities, then the purity and reliability of the oxide semiconductor layer is improved, but the manufacturing process complexity and time are increased
Solution Approach 1:
Heat treatment for dehydration and dehydrogenation is performed on the oxide semiconductor layer before forming the source and drain electrodes. This preliminary purification action removes impurities such as water and hydrogen in advance, ensuring high transistor reliability and stable electrical characteristics before subsequent manufacturing steps are completed.
2Stability of the object's composition
If heat treatment is performed to dehydrate and dehydrogenate the oxide semiconductor layer, then the electric characteristics stability is improved, but the manufacturing time and energy consumption are increased
Solution Approach 1:
The oxide semiconductor layer undergoes heat treatment for dehydration and dehydrogenation before electrode formation. This preliminary stabilization ensures that the layer achieves desired electrical characteristics and compositional stability prior to subsequent manufacturing steps, preventing later adjustments and reducing total manufacturing time.
3Manufacturing precision
If slow cooling is performed after heat treatment, then the crystal structure and purity are improved, but the manufacturing cycle time is extended
Solution Approach 1:
The oxide semiconductor layer undergoes controlled phase transition during slow cooling after heat treatment. This controlled cooling process allows proper crystallization and structural stabilization, improving manufacturing precision and electrical characteristics while managing the necessary time investment for quality outcomes.
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 enhances the stability and reliability of thin film transistors by reducing moisture and hydrogen impurities, leading to improved electric characteristics and increased durability.
Implementation Method 1
heat treatment which reduces impurities such as moisture to improve the purity of the oxide semiconductor layer (heat treatment for dehydration or dehydrogenation) is performed in an oxygen atmosphere
Implementation Method 2
heat treatment for dehydration or dehydrogenation is performed in an oxygen atmosphere
Implementation Method 3
heat treatment for dehydration or dehydrogenation is performed in an oxygen atmosphere
Implementation Method 4
the heat treatment can oxidize the oxide semiconductor layer
Implementation Method 5
After the heat treatment, it is preferable that the oxide semiconductor layer be slowly cooled in the/an oxygen atmosphere or an inert gas atmosphere of nitrogen or a rare gas
Data Source
AI summary
A highly reliable semiconductor device which includes a thin film transistor having stable electric characteristics, and a manufacturing method thereof. In the manufacturing method of the semiconductor device which includes a thin film transistor where a semiconductor layer including a channel formation region is an oxide semiconductor layer, heat treatment which reduces impurities such as moisture to improve the purity of the oxide semiconductor layer and oxidize the oxide semiconductor layer (heat treatment for dehydration or dehydrogenation) is performed. Not only impurities such as moisture in the oxide semiconductor layer but also those existing in a gate insulating layer are reduced, and impurities such as moisture existing in interfaces between the oxide semiconductor layer and films provided over and under and in contact with the oxide semiconductor layer are reduced.