Oxide Semiconductor Transistor Structure for Low Characteristic Variation
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving small variations in transistor characteristics, high on-state current, favorable electrical characteristics, miniaturization, high integration, high reliability, and low power consumption.
Innovation Solution
A semiconductor device is designed with a specific structure including a first insulator, a first oxide, a first conductor, a second conductor, and a second oxide positioned between the conductors over the first oxide, with a second insulator and a third conductor on top. The top surface of the first oxide under the third conductor is lower than under the first conductor, with a curved surface having a curvature radius between 1 nm and 15 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional transistor structure is used, then manufacturing is simpler, but transistor characteristic variation is large
Solution Approach 1:
The patent applies local quality by creating different oxide layer configurations in different regions: a first oxide layer is formed in the channel formation region, while a second oxide layer is formed in the source and drain regions. This local differentiation optimizes transistor characteristics by reducing variation while maintaining manufacturability through region-specific material properties.
Solution Approach 2:
The oxide semiconductor layer is segmented into multiple distinct layers (first oxide layer in channel region, second oxide layer in source/drain regions) with different compositions and properties. This segmentation allows independent optimization of each region's characteristics, reducing overall transistor variation while keeping the manufacturing process manageable.
2Area of moving object
If transistor size is reduced for miniaturization, then integration density increases, but on-state current decreases
Solution Approach 1:
The patent changes material parameters by using different oxide compositions in different regions. The first oxide layer in the channel region has specific properties that maintain high on-state current, while the second oxide layer in source/drain regions has properties that facilitate carrier injection. This parameter differentiation allows miniaturized transistors to maintain adequate current levels.
Solution Approach 2:
The transistor employs composite oxide semiconductor materials with different compositions and crystalline structures in different regions. The channel region uses a specific oxide composition optimized for carrier transport, while source/drain regions use different compositions optimized for carrier injection, enabling miniaturization without severe current loss.
Data Source
AI summary
A semiconductor device in which a variation of transistor characteristics is small is provided. The semiconductor device includes a transistor. The transistor includes a first insulator, a first oxide over the first insulator, a first conductor, a second conductor, and a second oxide, which is positioned between the first conductor and the second conductor, over the first oxide, a second insulator over the second oxide, and a third conductor over the second insulator. A top surface of the first oxide in a region overlapping with the third conductor is at a lower position than a position of a top surface of the first oxide in a region overlapping with the first conductor. The first oxide in the region overlapping with the third conductor has a curved surface between a side surface and the top surface of the first oxide, and the curvature radius of the curved surface is greater than or equal to 1 nm and less than or equal to 15 nm.