Oxide Semiconductor Transistor with Segmented Impurity Regions
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Solution Overview
Problem
Existing semiconductor devices with oxide semiconductor transistors face challenges in achieving stable electrical characteristics and low power consumption due to hydrogen diffusion affecting channel formation regions, leading to variations in resistance and performance.
Innovation Solution
A self-aligned transistor structure is developed with an oxide semiconductor film, featuring regions with different impurity element concentrations, including rare gas elements or hydrogen, boron, nitrogen, fluorine, aluminum, and phosphorus, to control resistance and stability, and a nitride insulating film to manage hydrogen diffusion, ensuring low resistance and reduced variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hydrogen is introduced into the oxide semiconductor film to form low-resistance source and drain regions, then the resistance of source and drain regions is reduced, but hydrogen diffuses to the channel formation region causing unstable semiconductor characteristics
Solution Approach 1:
The oxide semiconductor film is divided into distinct regions with different impurity concentrations: a channel formation region with low impurity concentration for stability, and source/drain regions with high impurity concentration for low resistance. This spatial segmentation allows each region to fulfill its specific function without interference.
Solution Approach 2:
Different regions of the oxide semiconductor film are given different local properties through selective impurity introduction. The source and drain regions have high impurity concentration (including hydrogen) for low resistance, while the channel formation region maintains low impurity concentration for stable characteristics, achieving local optimization of electrical properties.
2Ease of manufacture
If a silicon nitride film is formed by plasma CVD to introduce hydrogen into the oxide semiconductor film, then low-resistance regions are formed, but hydrogen diffusion to the channel region causes variations in electrical characteristics
Solution Approach 1:
A barrier layer is formed between the silicon nitride film and the oxide semiconductor film before hydrogen introduction. This preliminary barrier structure prevents hydrogen from diffusing into the channel formation region during subsequent heat treatment, ensuring that hydrogen only affects the source and drain regions as intended.
Solution Approach 2:
A barrier layer acts as an intermediary between the hydrogen source (silicon nitride film) and the oxide semiconductor film. This intermediate layer selectively blocks hydrogen diffusion to the channel region while allowing the desired hydrogen introduction in source/drain regions, mediating the hydrogen introduction process to achieve precise control.
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 solution provides transistors with excellent electrical characteristics, reduced variations, and low power consumption, enhancing the performance and reliability of semiconductor devices.
Implementation Method 1
hydrogen included in the silicon nitride film is introduced into the oxide semiconductor film
Data Source
AI summary
A semiconductor device includes an oxide semiconductor film, a gate electrode overlapping the oxide semiconductor film with a gate insulating film therebetween, a nitride insulating film in contact with the oxide semiconductor film, and a conductive film in contact with the oxide semiconductor film. The oxide semiconductor film includes a first region in contact with the gate insulating film and a second region in contact with the conductive film. The second region contains an impurity element. The impurity element concentration of the second region is different from that of the first region.