Oxide Semiconductor Transistor Data Retention During Power Stop
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Solution Overview
Problem
Semiconductor devices face challenges in reducing power consumption and preventing operation delays due to the need to store and restore data in volatile memory devices when power is stopped, as existing solutions require external auxiliary memory for data restoration.
Innovation Solution
A semiconductor device with a node that holds data using a transistor with an oxide semiconductor layer, allowing data to be stored and restored without external power, by electrically connecting nodes through the transistor's source and drain, and controlling the connection to minimize power consumption and operation delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If supply of power source voltage is stopped to reduce power consumption, then power consumption is reduced, but data in volatile memory devices is lost and operation delay occurs
Solution Approach 1:
The patent applies preliminary action by storing data from volatile memory (flip-flops) to nonvolatile memory (ferroelectric memory) before power is stopped. This advance data preservation ensures that when power is restored, the data is already available in nonvolatile storage, eliminating the need for time-consuming data restoration operations and preventing operation delays.
Solution Approach 2:
The patent introduces nonvolatile memory (ferroelectric memory) as an intermediary between volatile memory and external auxiliary memory. This intermediary component enables data to be temporarily stored within the semiconductor device itself during power stop periods, eliminating the need for external auxiliary memory and reducing operation delay while maintaining low power consumption.
2Reliability
If external auxiliary memory is used to restore data after power stop, then data can be restored, but device complexity increases
Solution Approach 1:
The patent merges volatile memory (flip-flops) and nonvolatile memory (ferroelectric memory) into a single integrated memory system within the semiconductor device. This combination allows the device to maintain data storage capability during power stop without requiring external auxiliary memory, thereby reducing device complexity while ensuring reliable data restoration.
Solution Approach 2:
The patent enables the semiconductor device to serve itself by incorporating nonvolatile memory that can autonomously retain data without external intervention. The ferroelectric memory automatically preserves data during power stop and restores it when power is restored, eliminating the need for external auxiliary memory and simplifying the overall device architecture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces power consumption and prevents operation delays by allowing data to be stored and restored within the device itself, even when power is stopped, using a low off-state current transistor to maintain data integrity.
Implementation Method 1
the off-state current value of the transistor is extremely low. For that reason, electric charge scarcely leaks through the transistor from the latter node
Data Source
AI summary
A novel semiconductor device and a driving method thereof are provided. In the semiconductor device, a (volatile) node which holds data that is rewritten by arithmetic processing as appropriate and a node in which the data is stored are electrically connected through a source and a drain of a transistor whose channel is formed in an oxide semiconductor layer. The off-state current value of the transistor is extremely low. Therefore, electric charge scarcely leaks through the transistor from the latter node, and thus data can be held in the latter node even in a period during which supply of power source voltage is stopped. In the semiconductor device, a means of setting the potential of the latter node to a predetermined potential is provided. Specifically, a means of supplying a potential corresponding to “1” or “0” that is data stored in the latter node from the former node is provided.