Oxide Semiconductor Memory Structure for Fast Access and Long Data Hold

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing semiconductor storage devices, such as DRAM and flash memory, face challenges with data retention time, power consumption, and the need for frequent refresh operations in volatile devices, while non-volatile devices like flash memory suffer from limited write cycles and high voltage requirements.

Innovation Solution

A semiconductor device with a layered structure incorporating a transistor using an oxide semiconductor and another transistor using a material other than oxide semiconductor, allowing for long-term data retention without the need for refresh operations and enabling high-speed data writing and reading.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a volatile storage device (DRAM) is used to store data, then writing and reading operations can be performed quickly, but the data holding time is short and refresh operations are required at predetermined intervals

Engineering Contradiction:

Improvewriting and reading speedVSAvoiddata holding time

Core Design Contradiction:

SpeedVSDuration of action of moving object

Solution Approach 1:

The invention divides the storage system into two distinct parts: a volatile storage element (DRAM) for fast write/read operations and a non-volatile storage element for long-term data retention. This segmentation allows each part to perform its specialized function optimally without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention combines a volatile storage element and a non-volatile storage element into a single integrated storage system. The volatile element handles frequent access operations while the non-volatile element preserves data, merging the advantages of both storage types into one unified structure.

Inventive Principle:

Principle #5Merging (Combining)

2Device complexity

If a volatile storage device (DRAM) is used, then the structure can be simple, but power consumption cannot be sufficiently reduced due to required refresh operations

Engineering Contradiction:

Improvestructure simplicityVSAvoidpower consumption

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

The storage system is segmented into volatile and non-volatile portions, allowing the non-volatile part to retain data without power while the volatile part maintains simplicity for fast operations. This reduces overall power consumption by eliminating the need to continuously power the entire storage array.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of continuous refresh operations required by traditional DRAM, the invention uses periodic data transfer between volatile and non-volatile elements. Data is moved to non-volatile storage less frequently, reducing the overall refresh burden and power consumption.

Inventive Principle:

Principle #19Periodic action

3Duration of action of moving object

If a non-volatile storage device (flash memory) is used to retain data for long time, then refresh operations are not needed, but the gate insulating layer deteriorates by tunneling current after a predetermined number of writing operations

Engineering Contradiction:

Improvedata holding timeVSAvoidwrite cycle lifetime

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The invention segments the storage workload between volatile and non-volatile elements. The volatile DRAM element handles frequent write operations that would otherwise stress the non-volatile element's gate insulating layer, thereby extending the write cycle lifetime of the non-volatile portion.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The volatile storage element acts as an intermediary buffer between external write operations and the non-volatile storage element. This mediator absorbs the stress of frequent writing, protecting the non-volatile element's gate insulating layer from excessive tunneling current damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Duration of action of moving object

If a non-volatile storage device (flash memory) is used, then data can be retained permanently, but high voltage is necessary for holding or removing electric charge which slows down writing and erasing operations

Engineering Contradiction:

Improvedata retention timeVSAvoidwriting and erasing speed

Core Design Contradiction:

Duration of action of moving objectVSSpeed

Solution Approach 1:

The storage system is divided into a volatile component for high-speed operations and a non-volatile component for permanent retention. This segmentation allows fast write/erase operations in the volatile portion without requiring high voltage, while the non-volatile portion handles long-term storage needs.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention merges volatile and non-volatile storage elements into an integrated system where the volatile element provides high-speed access and the non-volatile element provides permanent retention. This combination achieves both high writing speed and long-term data retention simultaneously.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12211534B2Semiconductor device

Publication Date: 2025.01.28 SEMICON ENERGY LAB CO LTD

AI summary

An object is to provide a semiconductor device with a novel structure. The semiconductor device includes a first wiring; a second wiring; a third wiring; a fourth wiring; a first transistor having a first gate electrode, a first source electrode, and a first drain electrode; and a second transistor having a second gate electrode, a second source electrode, and a second drain electrode. The first transistor is provided in a substrate including a semiconductor material. The second transistor includes an oxide semiconductor layer.