Oxide Semiconductor Electrode Structure for Threshold Voltage Stability
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Solution Overview
Problem
Oxide semiconductor transistors used in memory cells face challenges with heat treatment, leading to fluctuating threshold voltages and reduced heat resistance due to oxygen deficiency and absorption issues during the manufacturing process.
Innovation Solution
The semiconductor device incorporates a specific electrode structure with regions of indium, zinc, and oxygen, along with metal elements like titanium, tantalum, and tungsten, where the third and fourth regions have higher oxygen concentrations, preventing oxygen absorption and maintaining high resistance, thus stabilizing the threshold voltage and enhancing heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide semiconductor transistor undergoes heat treatment during memory cell and wiring formation, then memory cell structure is formed, but threshold voltage fluctuates and heat resistance decreases due to oxygen deficiency and absorption
Solution Approach 1:
The patent applies preliminary action by forming a protective oxide layer on the oxide semiconductor layer before heat treatment. This protective layer prevents oxygen deficiency and absorption during subsequent heat treatment processes, thereby maintaining threshold voltage stability and heat resistance. The protective structure is prepared in advance to counteract the harmful effects of heat treatment.
Solution Approach 2:
The patent introduces an intermediary protective oxide layer between the oxide semiconductor layer and the external environment during heat treatment. This intermediary layer acts as a barrier that prevents oxygen loss from and absorption into the oxide semiconductor layer, thus maintaining its electrical characteristics and preventing threshold voltage fluctuations.
2Reliability
If oxide semiconductor transistor is used in memory cell switching transistor, then excellent off-operation characteristics are achieved, but heat treatment causes oxygen issues leading to performance degradation
Solution Approach 1:
The patent converts the harmful effect of heat treatment into a beneficial outcome by using the heat treatment process to form a protective oxide layer on the oxide semiconductor layer. This protective layer, which would normally be considered an additional complexity, actually protects the oxide semiconductor from oxygen deficiency and absorption, thereby maintaining the excellent off-operation characteristics.
Solution Approach 2:
The patent creates an inert protective environment by forming an oxide layer on the oxide semiconductor layer before heat treatment. This protective layer acts as an inert barrier that isolates the oxide semiconductor from oxygen-related harmful effects during heat treatment, preserving its electrical characteristics.
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 configuration effectively suppresses threshold voltage fluctuations and improves the heat resistance of oxide semiconductor transistors, ensuring reliable operation even after heat treatment.
Implementation Method 1
the third region having an atomic concentration of oxygen (O) higher than an atomic concentration of oxygen (O) of the second region, and the fourth region having an atomic concentration of oxygen (O) higher than an atomic concentration of oxygen (O) of the second region
Data Source
AI summary
Provided is a semiconductor device of the embodiment including: an oxide semiconductor layer; a gate electrode; a first electrode electrically connected to one portion of the oxide semiconductor layer, the first electrode including a first region, second region, a third region, and a fourth region, the first region disposed between the first portion and the second region, the first region disposed between the third region and the fourth region, the first region containing at least one element of In, Zn, Sn or Cd, and oxygen, the second region containing at least one metal element of Ti, Ta, W, or Ru, the third region and the fourth region containing the at least one metal element and oxygen, the third region and the fourth region having an atomic concentration of oxygen higher than that of the second region; and a second electrode electrically connected to another portion of the oxide semiconductor layer.