Oxide Semiconductor Stack for High Drain Current Power Devices
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Solution Overview
Problem
Current semiconductor devices using silicon for power applications face limitations in performance due to high temperature operation constraints and difficulty in achieving high drain current, prompting the need for alternative materials like SiC or GaN, but these also have limitations.
Innovation Solution
A semiconductor device with a stacked-layer structure incorporating oxide semiconductors, including a first and second oxide semiconductor layer with varying concentrations of conductivity elements, and a gate electrode configuration that enhances current flow and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon is used for power device, then the device structure is simple and manufacturing is easy, but the operation temperature is limited due to small band gap
Solution Approach 1:
The patent employs a composite material structure combining oxide semiconductor layers with metal layers (such as Al-In-Ga-Zn-O system). This composite approach enables the device to achieve high-temperature operation capability while maintaining ease of manufacture through established thin-film deposition techniques.
2Temperature
If SiC or GaN is used to achieve wide band gap and high temperature operation, then the operation temperature is improved, but the device complexity increases
Solution Approach 1:
The patent changes the material parameters by using oxide semiconductor compositions with specific metal ratios (Al-In-Ga-Zn-O system) to achieve wide band gap characteristics. This allows high-temperature operation while maintaining a relatively simple layered device structure compared to conventional SiC or GaN devices.
3Ease of manufacture
If conventional oxide semiconductor structure is used, then the manufacturing process is simple, but the drain current is insufficient for power applications
Solution Approach 1:
The patent implements local quality variation by creating a multi-layer oxide semiconductor structure where different layers have different compositions and conductivity characteristics. The metal layers (Al-In-Ga-Zn-O) are strategically positioned to enhance carrier concentration and conductivity in specific regions, thereby increasing drain current while maintaining overall manufacturing simplicity.
4Power
If high conductivity is achieved by adding elements to oxide semiconductor, then the drain current is improved, but the series resistance increases
Solution Approach 1:
The patent addresses the series resistance issue by transitioning from a single-layer to a multi-layer vertical structure. The conductive metal layers are positioned at specific depths within the oxide semiconductor stack, creating optimized current pathways that reduce series resistance while maintaining high drain current capability.
Data Source
AI summary
An object is to provide a semiconductor device that includes an oxide semiconductor and is suitable for a power device. An object is to provide a semiconductor device in which large current can flow. An object is to provide a highly reliable semiconductor device. A semiconductor device includes an oxide stack in which a first oxide layer, a first oxide semiconductor layer, a second oxide semiconductor layer, and a second oxide layer are stacked and has a structure in which a region that contains an element imparting conductivity and is provided in the first oxide semiconductor layer overlaps an electrode functioning as a source electrode and does not overlap an electrode functioning as a drain electrode.