Oxide Semiconductor Power Gating for Low-Standby ICs
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Solution Overview
Problem
The increasing integration of semiconductor integrated circuits leads to higher standby power consumption due to increased leakage currents and parasitic capacitance, which existing technologies struggle to address effectively.
Innovation Solution
Utilizing a transistor with an oxide semiconductor as a switching element to control the supply of power supply voltage to the circuit, reducing leakage current and integrating crystalline silicon for high-speed operation, and employing a highly-purified oxide semiconductor to minimize off-current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the integration degree of the integrated circuit is increased, then the productivity and functionality are improved, but the standby power consumption increases due to increased leakage current
Solution Approach 1:
The patent changes the material parameter of the switching element from conventional semiconductor materials to highly-purified oxide semiconductor, which fundamentally alters the electrical characteristics to achieve extremely low off-current density (less than 1×10^-21 A/cm), thereby resolving the standby power issue while maintaining high integration
Solution Approach 2:
The patent employs a composite structure combining highly-purified oxide semiconductor with specific impurity concentrations (hydrogen: less than 5×10^19 atoms/cm³, moisture: less than 1×10^20 molecules/cm³) to create a switching element that achieves both high integration capability and ultra-low leakage current
2Productivity
If the channel length of the transistor is shortened to increase integration, then the productivity is improved, but the leakage current increases and standby power consumption increases
Solution Approach 1:
The patent changes the fundamental material parameter of the transistor channel from conventional semiconductor to highly-purified oxide semiconductor, which maintains extremely low off-current density even when channel length is shortened, enabling high integration without the usual leakage current penalty
3Productivity
If the thickness of the gate insulating film is reduced to increase integration, then the productivity is improved, but the leakage current increases and standby power consumption increases
Solution Approach 1:
The patent changes the switching element material to highly-purified oxide semiconductor, which compensates for the reduced gate insulating film thickness by providing extremely low inherent leakage current through its purified state, allowing thin gate insulators without increasing standby power
4Loss of energy
If a transistor is used as a switching element to stop power supply voltage in stop state, then the dynamic standby power is reduced, but the leakage current of the transistor increases with higher integration degree
Solution Approach 1:
The patent creates a composite material system with highly-purified oxide semiconductor containing specific impurity concentrations (hydrogen less than 5×10^19 atoms/cm³, moisture less than 1×10^20 molecules/cm³), which achieves extremely low off-current density that overcomes the integration-related leakage increase, enabling effective power gating
Data Source
AI summary
An object is to provide a semiconductor device with reduced standby power. A transistor including an oxide semiconductor as an active layer is used as a switching element, and supply of a power supply voltage to a circuit in an integrated circuit is controlled by the switching element. Specifically, when the circuit is in an operation state, supply of the power supply voltage to the circuit is performed by the switching element, and when the circuit is in a stop state, supply of the power supply voltage to the circuit is stopped by the switching element. In addition, the circuit supplied with the power supply voltage includes a semiconductor element which is a minimum unit included in an integrated circuit formed using a semiconductor. Further, the semiconductor included in the semiconductor element contains silicon having crystallinity (crystalline silicon).