Dual-Gate Oxide Semiconductor Transistor Fabrication
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Solution Overview
Problem
Current oxide-semiconductor transistors lack flexibility in providing multiple threshold voltage (Vt) options and have insufficient Ion/Ioff performance, limiting their fabrication and structural improvements.
Innovation Solution
A method involving the formation of a channel layer, gate dielectric layer, source and drain layers, a bottom gate, phase change layer, and a top gate is employed, with specific materials and processes like high-k dielectric materials and phase change materials like germanium antimony telluride to enhance device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional oxide-semiconductor transistor structure is used, then the fabrication process is simple, but the device lacks flexibility in providing multiple threshold voltage options and has insufficient Ion/Ioff performance
Solution Approach 1:
The gate structure is segmented into a bottom gate and a top gate, separated by an insulating layer. This segmentation allows independent control of threshold voltage through the bottom gate and enhancement of Ion/Ioff characteristics through the top gate, thereby providing multiple Vt options while maintaining fabrication feasibility
Solution Approach 2:
The top gate is formed within a recess of the insulating layer, creating a nested structure where the top gate is embedded in the insulating material. This nesting approach enables complex gate functionality without significantly increasing overall device footprint or fabrication complexity
2Reliability
If a conventional oxide-semiconductor transistor structure is used, then the fabrication process is straightforward, but the Ion/Ioff performance is insufficient
Solution Approach 1:
The gate is divided into bottom gate and top gate components that work together to achieve superior Ion/Ioff performance. The bottom gate provides threshold voltage control while the top gate enhances carrier accumulation, resulting in improved switching characteristics without overly complicating the fabrication process
Solution Approach 2:
The transistor employs an oxide semiconductor film as the active layer, which inherently provides low leakage current. This composite material approach, combining oxide semiconductor with the dual-gate structure, achieves high Ion/Ioff performance while maintaining compatibility with existing fabrication techniques
Data Source
AI summary
A method for fabricating a semiconductor device includes the steps of: forming a channel layer on a substrate; forming a gate dielectric layer on the channel layer; forming a source layer near one side of the gate dielectric layer and a drain layer near another side of the gate dielectric layer; forming a bottom gate on the gate dielectric layer; forming a phase change layer on the bottom gate; and forming a top gate on the phase change layer.