Oxide Semiconductor Transistor Gate Insulator Hydrogen Control
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Solution Overview
Problem
In oxide semiconductor transistors, drain current flows even when the gate voltage is zero due to negative shifts in threshold voltage caused by hydrogen diffusion from insulating layers with high hydrogen content.
Innovation Solution
Using insulating layers with a hydrogen concentration less than 6×10^20 atoms/cm^3, preferably less than 5×10^19 atoms/cm^3, to prevent hydrogen diffusion into the oxide semiconductor layer, thereby maintaining favorable electric characteristics without increasing manufacturing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If insulating layers with high hydrogen content are used, then ease of manufacture is improved, but threshold voltage shifts negatively causing drain current leakage
Solution Approach 1:
The patent changes the hydrogen concentration parameter of the insulating layer from high to low content. Specifically, it uses an insulating layer with hydrogen concentration of less than 6×10^20 atoms/cm³ (preferably less than 5×10^19 atoms/cm³) to prevent hydrogen diffusion into the oxide semiconductor layer, thereby stabilizing the threshold voltage and eliminating drain current leakage while maintaining manufacturability
Solution Approach 2:
The patent applies local quality by specifically controlling the hydrogen content in the insulating layer that is in direct contact with the oxide semiconductor layer. This localized control of hydrogen concentration at the critical interface prevents threshold voltage shifts without requiring changes to the entire device structure or manufacturing process
2Reliability
If hydrogen diffusion prevention measures are taken, then threshold voltage stability is improved, but device complexity increases
Solution Approach 1:
The patent achieves threshold voltage stability by changing the material parameter (hydrogen concentration) of the insulating layer rather than adding complex structural elements or processing steps. The insulating layer with controlled hydrogen content serves as a barrier to hydrogen diffusion, preventing threshold voltage shifts without increasing device complexity
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
Prevents hydrogen diffusion, maintains favorable electric characteristics, and avoids the degradation of transistor performance by ensuring the insulating layers have low hydrogen content, specifically in the gate and oxide semiconductor layers.
Implementation Method 1
diffusion of hydrogen into the oxide semiconductor layer can be prevented
Data Source
AI summary
In a transistor having a top-gate structure in which a gate electrode layer overlaps with an oxide semiconductor layer which faints a channel region with a gate insulating layer interposed therebetween, when a large amount of hydrogen is contained in the insulating layer, hydrogen is diffused into the oxide semiconductor layer because the insulating layer is in contact with the oxide semiconductor layer; thus, electric characteristics of the transistor are degraded. An object is to provide a semiconductor device having favorable electric characteristics. An insulating layer in which the concentration of hydrogen is less than 6×1020 atoms/cm3 is used for the insulating layer being in contact with oxide semiconductor layer which forms the channel region. Using the insulating layer, diffusion of hydrogen can be prevented and a semiconductor device having favorable electric characteristics can be provided.