Oxide Semiconductor Transistor for Non-Volatile Memory
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Solution Overview
Problem
Conventional semiconductor devices, such as DRAM and flash memory, face challenges with data retention time, power consumption, and the limitations of write cycles due to high leakage currents and the need for frequent refresh operations or high voltage for data storage.
Innovation Solution
A semiconductor device utilizing a purified oxide semiconductor with a unique transistor structure that includes both oxide and non-oxide semiconductor materials, minimizing off-state current and eliminating the need for high voltage, allowing for long-term data retention without refresh operations and unlimited write cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a conventional transistor is used in DRAM, then the device can store data using a capacitor, but the leakage current causes short data retention time and requires frequent refresh operations
Solution Approach 1:
The patent changes the material parameter of the transistor from conventional semiconductor to oxide semiconductor, which fundamentally alters the electrical characteristics to achieve extremely low leakage current and long data retention without refresh operations
Solution Approach 2:
The patent employs a composite structure combining oxide semiconductor layer with other functional layers (gate electrode, gate insulator, source/drain electrodes) to create a transistor with unique properties that achieve both non-volatile storage and low power consumption
2Duration of action of stationary object
If flash memory is used for non-volatile storage, then data retention time is extremely long, but the gate insulating layer deteriorates due to tunneling current after a predetermined number of writing operations
Solution Approach 1:
The patent changes the writing mechanism from high-voltage tunneling current injection (flash memory) to low-voltage charge transfer through oxide semiconductor, eliminating the deterioration problem while maintaining non-volatile storage capability
Solution Approach 2:
The patent replaces the fragile gate insulating layer in flash memory with a robust oxide semiconductor-based structure that can withstand repeated writing operations without degradation
3Duration of action of stationary object
If flash memory is used, then high voltage is necessary for holding or removing electric charge, but this increases circuit complexity and writing time
Solution Approach 1:
The patent changes the operating voltage parameter from high voltage (flash memory) to low voltage (oxide semiconductor transistor), simplifying the circuit structure and enabling faster writing operations while maintaining non-volatile storage
4Duration of action of moving object
If a transistor with small off-state current is used, then data can be retained for a long time, but the manufacturing process becomes more complex due to purified oxide semiconductor requirements
Solution Approach 1:
The patent changes the manufacturing approach by using oxide semiconductor materials that can be processed at lower temperatures and with simpler techniques compared to conventional high-purity semiconductor manufacturing, reducing overall process complexity
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 semiconductor device achieves extended data retention, reduced power consumption, and increased reliability by minimizing off-state current and eliminating the need for high voltage, enabling high-speed operation and high integration density.
Implementation Method 1
A transistor including an oxide semiconductor has an extremely small leakage current, so that data can be retained for a long time
Data Source
AI summary
An object is to provide a semiconductor device in which stored data can be retained even when power is not supplied, and there is no limitation on the number of write cycles. The semiconductor device includes a source line, a bit line, a first signal line, a second signal line, a word line, a memory cell connected between the source line and the bit line, a first driver circuit electrically connected to the bit line, a second driver circuit electrically connected to the first signal line, a third driver circuit electrically connected to the second signal line, and a fourth driver circuit electrically connected to the word line and the source line. The first transistor is formed using a semiconductor material other than an oxide semiconductor. The second transistor is formed using an oxide semiconductor material.