Oxide Semiconductor Storage Gate for Non-Volatile Memory
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Solution Overview
Problem
Current semiconductor storage devices, such as DRAM and flash memory, face limitations in data retention time, power consumption, and number of write cycles, with DRAM requiring frequent refresh operations and flash memory experiencing gate insulating layer deterioration and high voltage requirements.
Innovation Solution
A semiconductor device utilizing an oxide semiconductor storage gate that can be made conductive or insulative to store data, eliminating the need for high voltage and reducing power consumption, with data retention for extended periods without the need for refresh operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a DRAM storage element is used, then data can be stored using a simple transistor-capacitor structure, but the data retention time is short and frequent refresh operations are required
Solution Approach 1:
The patent changes the electrical state parameter of the oxide semiconductor layer by applying specific voltages to transform it between conductive and insulative states. When conductive, the storage gate can be charged; when insulative, the charge is retained for long periods without refresh operations, solving the data retention problem while maintaining structural simplicity
Solution Approach 2:
The patent uses a composite structure combining an oxide semiconductor layer with gate insulating layers and electrode layers. The oxide semiconductor's unique property of being transformable between conductive and insulative states creates a novel storage mechanism that achieves both simple structure and long data retention
2Duration of action of stationary object
If a flash memory storage element is used, then data retention time is extremely long and refresh operations are not needed, but the gate insulating layer deteriorates after limited write operations
Solution Approach 1:
The patent applies voltage parameters to transform the oxide semiconductor layer between conductive and insulative states for writing operations. This parameter-based switching mechanism allows repeated write operations without the gate insulating layer deterioration that plagues flash memory, while maintaining the ability to retain data for extended periods
Solution Approach 2:
The oxide semiconductor layer acts as a reusable, non-deteriorating switching element that can be transformed between states indefinitely. Unlike the gate insulating layer in flash memory which degrades with each write cycle, the oxide semiconductor maintains its properties through repeated use, enabling unlimited write cycles
3Duration of action of stationary object
If a flash memory storage element is used, then data can be retained permanently, but high voltage is required to inject or remove electric charge
Solution Approach 1:
The patent uses controlled voltage parameters to transform the oxide semiconductor layer between conductive and insulative states. This allows charge injection and removal at lower voltages compared to flash memory, reducing energy consumption while maintaining permanent data retention capability
Solution Approach 2:
The oxide semiconductor layer provides localized conductive or insulative properties in the storage gate region. This localized property change enables efficient charge storage and retrieval at lower voltages, eliminating the need for high voltage operations required by flash memory
4Duration of action of stationary object
If an SRAM storage element is used, then no refresh operation is needed, but the cost per storage capacity is increased
Solution Approach 1:
The patent transforms the oxide semiconductor layer between conductive and insulative states through voltage application, creating a simple single-transistor storage element. This parameter-based mechanism achieves SRAM-like no-refresh operation without the complex flip-flop circuitry, reducing cost per storage capacity
Solution Approach 2:
The patent extracts the essential function of long-term data retention from complex SRAM flip-flop circuits and implements it through a simple transistor with an oxide semiconductor-based storage gate. This extraction achieves the benefit of no refresh operations while eliminating the circuit complexity and associated costs
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 long-term data retention, reduced power consumption, and increased reliability with high integration and storage capacity, enabling high-speed operation and extended write cycle durability.
Implementation Method 1
A semiconductor device utilizing an oxide semiconductor storage gate that can be made conductive or insulative to store data
Data Source
AI summary
Disclosed is a semiconductor device having a memory cell which comprises a transistor having a control gate and a storage gate. The storage gate comprises an oxide semiconductor and is able to be a conductor and an insulator depending on the potential of the storage gate and the potential of the control gate. Data is written by setting the potential of the control gate to allow the storage gate to be a conductor, supplying a potential of data to be stored to the storage gate, and setting the potential of the control gate to allow the storage gate to be an insulator. Data is read by supplying a potential for reading to a read signal line connected to one of a source and a drain of the transistor and detecting the change in potential of a bit line connected to the other of the source and the drain.