Oxide Semiconductor Microvoid Nitrogen Adsorption
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Oxide semiconductor transistors with short channel lengths often fail to achieve a sufficient on/off ratio due to hydrogen diffusion, leading to constant drain current regardless of gate voltage, which compromises their functionality as switching elements in electronic and optical devices.
Innovation Solution
Incorporating a microvoid with high nitrogen or oxygen concentration in the oxide semiconductor layer, where hydrogen is adsorbed to prevent oxygen extraction, thereby maintaining a sufficient on/off ratio while minimizing the impact on on-state current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the channel length L is shortened to miniaturize the oxide semiconductor transistor, then miniaturization is achieved, but the on/off ratio becomes insufficient due to hydrogen diffusion effects
Solution Approach 1:
The patent applies preliminary action by forming a protective layer containing nitrogen or oxygen before the transistor is miniaturized and before heat treatment. This protective layer prevents hydrogen from diffusing into the oxide semiconductor layer during subsequent heat treatment processes, thereby avoiding oxygen extraction and maintaining the on/off ratio even when the channel length is shortened for miniaturization.
Solution Approach 2:
The patent uses an intermediary substance (nitrogen or oxygen-containing layer) placed between the hydrogen source and the oxide semiconductor layer. This intermediary layer acts as a barrier that prevents hydrogen diffusion during heat treatment, protecting the oxide semiconductor layer from oxygen extraction while permitting the necessary thermal processing to occur, even in miniaturized devices with short channel lengths.
2Reliability
If nitrogen or oxygen is added to the upper layer of the oxide semiconductor layer, then hydrogen is adsorbed and oxygen extraction is prevented, but the structure complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition of the upper layer of the oxide semiconductor layer, specifically increasing the nitrogen or oxygen concentration. This compositional change enables the layer to adsorb hydrogen and prevent oxygen extraction from the semiconductor layer, achieving the desired protective effect through material parameter adjustment rather than adding separate structural components.
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 approach ensures a sufficient on/off ratio in oxide semiconductor transistors with short channel lengths, enhancing their reliability as switching elements by preventing oxygen extraction and maintaining on-state current integrity.
Implementation Method 1
Hydrogen from external air or an insulating film is adsorbed to the inner wall of the microvoid
Implementation Method 2
If heat treatment is performed on the oxide semiconductor layer which water or hydrogen has entered, hydrogen is diffused into the oxide semiconductor layer
Data Source
AI summary
The invention relates to a semiconductor device including an oxide semiconductor layer, a gate electrode overlapping with a channel formation region of the oxide semiconductor layer, and a source electrode or a drain electrode overlapping with a first region of the oxide semiconductor layer, and a second region between the channel formation region and the first region. An upper layer of the second region includes a microvoid. The microvoid is formed by adding nitrogen to the upper layer of the second region. Thus, upper layer of the second region contains lager amount of nitrogen than a lower layer of the second region.