Ferroelectric Neuromorphic Transistor Stack for Accurate In-Memory Computing

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Solution Overview

Problem

The Von Neumann computing architecture limits energy efficiency and processing speed for large data sets due to inefficient data transfer between main memory and CPU, and existing in-memory computing technologies using RRAM or PCM suffer from accuracy issues due to asymmetric and nonlinear weight changes.

Innovation Solution

The development of semiconductor devices and neuromorphic circuits incorporating ferroelectric materials, which enable efficient data processing by simulating synaptic functions, allowing for parallel processing and improved data storage and retrieval, thereby enhancing the accuracy and speed of data processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If Von Neumann architecture with separate main memory and CPU is used, then device structure is simple and ease of manufacture is improved, but data transfer efficiency deteriorates and power consumption increases

Engineering Contradiction:
Improveease of manufactureVSAvoidpower consumption
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent merges memory and computing functions into a single integrated device structure. The ferroelectric transistor stack combines storage (ferroelectric layer) and logic (transistor) functions, eliminating the need for separate memory and CPU components. This integration reduces data transfer distances and enables in-memory computing, directly addressing the energy efficiency problem while maintaining manufacturing feasibility through standardized semiconductor fabrication processes.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The ferroelectric transistor serves multiple functions simultaneously: it acts as both a memory element (storing data in the ferroelectric layer) and a logic element (performing computations through transistor operation). This multi-functionality allows the same physical structure to handle both storage and processing tasks, reducing the need for separate dedicated components and improving overall system efficiency.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Device complexity

If Von Neumann architecture with sequential data processing is used, then device structure is simple, but processing speed deteriorates for large data sets

Engineering Contradiction:
Improvedevice complexityVSAvoidprocessing speed
Core Design Contradiction:
Device complexityVSSpeed

Solution Approach 1:

The patent transitions from planar 2D transistor structures to vertically stacked 3D architectures. The multi-layer stack configuration allows multiple computational and storage elements to be integrated in the vertical dimension, enabling parallel processing operations without increasing lateral device footprint. This dimensional transition facilitates higher processing speeds while maintaining manageable device complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Speed

If RRAM or PCM is used for in-memory computing, then processing speed is improved, but measurement precision deteriorates due to asymmetric and nonlinear weight changes

Engineering Contradiction:
Improveprocessing speedVSAvoidaccuracy
Core Design Contradiction:
SpeedVSMeasurement precision

Solution Approach 1:

The patent changes the fundamental material parameter from resistive switching materials (RRAM/PCM) to ferroelectric materials. This parameter change enables linear and symmetric weight adjustments in the synaptic connections, improving measurement precision for neural network computations while maintaining high processing speeds through fast ferroelectric switching characteristics.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The device employs a composite structure combining ferroelectric materials with conventional semiconductor materials. This composite approach leverages the non-volatile memory properties and fast switching of ferroelectrics while maintaining compatibility with standard semiconductor fabrication, achieving both high speed and high precision simultaneously.

Inventive Principle:
Principle #40Composite materials

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 proposed solution achieves high accuracy in image recognition tasks, with a 97.3% identification rate on the MNIST dataset, significantly outperforming traditional technologies, while reducing power consumption and improving processing speed.

Implementation Method 1

The gate insulating film includes a ferroelectric material

Methodology Applied
Scientific EffectFerroelectricity:

Data Source

PatentUS11887989B2Semiconductor device including ferroelectric material, neuromorphic circuit including the semiconductor device, and neuromorphic computing apparatus including the neuromorphic circuit
Publication Date: 2024.01.30 SAMSUNG ELECTRONICS CO LTD
  • US11887989B2 patent drawing
  • US11887989B2 patent drawing
  • US11887989B2 patent drawing

AI summary

A semiconductor device includes a first transistor including a first channel layer of a first conductivity type, a second transistor provided in parallel with the first transistor and including a second channel layer of a second conductivity type, and a third transistor stacked on the first and second transistors. The third transistor may include a gate insulating film including a ferroelectric material. The third transistor may include third channel layer and a gate electrode that are spaced apart from each other in a thickness direction with the gate insulating film therebetween.