Oxide Semiconductor Transistor Stack for Stable Normally-Off Operation
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Solution Overview
Problem
Existing transistors face challenges in achieving stable electrical characteristics, low leakage current in the off state, high frequency characteristics, normally-off electrical characteristics, small subthreshold swing values, and high reliability.
Innovation Solution
A semiconductor device structure is proposed, which includes a first insulator with a halogen element over a substrate, a second insulator, an oxide semiconductor in contact with the second insulator, a third insulator in contact with the oxide semiconductor, and conductors electrically connected to the oxide semiconductor. This structure is designed to provide stable electrical characteristics and low leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transistor structures are used, then manufacturing is simpler, but electrical characteristics stability and reliability are insufficient
Solution Approach 1:
The transistor is divided into multiple functional regions including a first semiconductor region, a second semiconductor region, a third semiconductor region, and a fourth semiconductor region with different doping types and concentrations. This segmentation allows each region to be optimized for specific electrical characteristics, improving overall device reliability and stability.
Solution Approach 2:
Different regions of the transistor are assigned different local properties through varying doping types (n-type and p-type) and doping concentrations. The first and third semiconductor regions have different doping characteristics from the second and fourth regions, creating localized electrical properties that enhance device performance and reliability.
2Reliability
If high doping concentration is used, then conductivity is improved, but leakage current increases
Solution Approach 1:
The patent employs different doping concentrations in different regions to optimize the balance between conductivity and leakage current. By carefully controlling the doping parameters in each semiconductor region, the device achieves low leakage current in the off state while maintaining good conductivity in the on state.
Solution Approach 2:
The transistor structure combines multiple semiconductor regions with different doping characteristics (n-type and p-type) to create a composite structure. This composite approach allows the device to achieve both low leakage current and high conductivity by leveraging the complementary properties of different doped regions.
3Productivity
If simple transistor structure is used, then manufacturing is easier, but frequency characteristics and subthreshold swing are insufficient
Solution Approach 1:
The transistor is segmented into four distinct semiconductor regions with specific doping configurations, which enables improved frequency characteristics and subthreshold swing performance. This segmentation allows for optimized charge carrier control and reduced parasitic effects.
Solution Approach 2:
By adjusting the doping concentrations and types in different regions, the patent optimizes the transistor's frequency characteristics and subthreshold swing. The parameter variations in doping create favorable electrical fields that enhance device performance metrics.
Data Source
AI summary
A transistor with stable electrical characteristics. A semiconductor device includes a first insulator over a substrate, a second insulator over the first insulator, an oxide semiconductor in contact with at least part of a top surface of the second insulator, a third insulator in contact with at least part of a top surface of the oxide semiconductor, a first conductor and a second conductor electrically connected to the oxide semiconductor, a fourth insulator over the third insulator, a third conductor which is over the fourth insulator and at least part of which is between the first conductor and the second conductor, and a fifth insulator over the third conductor. The first insulator contains a halogen element.