Oxide Semiconductor TFT Processing for Stable Electric Characteristics
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Solution Overview
Problem
Existing methods for manufacturing semiconductor devices with oxide semiconductors struggle to achieve stable electric characteristics and high reliability due to impurities such as moisture in the oxide semiconductor layers and gate insulating layers.
Innovation Solution
The method involves forming oxide semiconductor films for the channel and source/drain regions, followed by heat treatment under an inert gas atmosphere to reduce impurities like moisture. The films are then slowly cooled under an oxygen atmosphere to further improve purity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is performed to reduce impurities in oxide semiconductor layers, then purity and reliability are improved, but manufacturing complexity and process time increase
Solution Approach 1:
The patent combines multiple heat treatment steps (dehydration and dehydrogenation) into a single integrated process. The oxide semiconductor layer undergoes simultaneous removal of water and hydrogen impurities through one heat treatment operation at 200-400°C in an inert or reducing atmosphere, eliminating the need for separate treatment steps and reducing overall manufacturing complexity while maintaining high reliability
Solution Approach 2:
The patent performs heat treatment for impurity removal immediately after forming the oxide semiconductor layer, before subsequent processing steps. This preliminary action prevents impurity accumulation and ensures high purity is achieved early in the manufacturing process, reducing the need for additional cleaning or treatment steps later
2Manufacturing precision
If multiple heat treatment steps are performed to remove impurities, then purity is improved, but manufacturing time and productivity are reduced
Solution Approach 1:
The patent merges dehydration and dehydrogenation treatments into one simultaneous heat treatment process. By using a reducing atmosphere (nitrogen, argon, or forming gas) at 200-400°C, the process removes both water and hydrogen impurities in a single step, achieving high purity oxide semiconductor layers without extending manufacturing time, thus maintaining high productivity
3Ease of manufacture
If impurities are not reduced in oxide semiconductor layers, then manufacturing is simpler and faster, but electric characteristics and reliability deteriorate
Solution Approach 1:
The patent changes the atmosphere parameter from ambient air to a controlled reducing atmosphere (nitrogen, argon, or forming gas) during heat treatment. This parameter change enables effective removal of water and hydrogen impurities at moderate temperatures (200-400°C) without complex equipment modifications, maintaining manufacturing simplicity while dramatically improving electric characteristic stability and device reliability
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 results in a thin film transistor with improved electric characteristics, higher productivity, and enhanced reliability by effectively reducing impurities and stabilizing the oxide semiconductor films.
Implementation Method 1
heat treatment (heat treatment for dehydration or dehydrogenation) is performed so as to improve the purity of the oxide semiconductor layer and reduce impurities such as moisture
Implementation Method 2
heat treatment (heat treatment for dehydration or dehydrogenation) is performed so as to improve the purity of the oxide semiconductor layer and reduce impurities such as moisture
Implementation Method 3
the first oxide semiconductor film and the second oxide semiconductor film are heated to be dedydrated or dehydrogenated and then slowly cooled under an oxygen atmosphere
Data Source
AI summary
It is an object to provide a highly reliable semiconductor device which includes a thin film transistor having stable electric characteristics. It is another object to manufacture a highly reliable semiconductor device at lower cost with high productivity. In a method for manufacturing a semiconductor device which includes a thin film transistor where a semiconductor layer having a channel formation region, a source region, and a drain region are formed using an oxide semiconductor layer, heat treatment (heat treatment for dehydration or dehydrogenation) is performed so as to improve the purity of the oxide semiconductor layer and reduce impurities such as moisture. Moreover, the oxide semiconductor layer subjected to the heat treatment is slowly cooled under an oxygen atmosphere.