Programmable Element With Floating Gate For Non-Volatile Memory

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Solution Overview

Problem

Existing non-volatile memory devices based on Transition Metal Oxides exhibit a large statistical spread of resistance values and limited endurance, and programmable logic devices are less efficient in terms of power consumption and area usage compared to application-specific integrated circuits.

Innovation Solution

A programmable element with a transition-metal oxide base that includes mobile ions, such as oxygen vacancies, which can be altered by applied electric fields to create four distinct states through voltage pulses applied to the source, drain, and gate electrodes, reducing the influence of statistical spread and enhancing endurance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Transition Metal Oxide based non-volatile memory devices are used, then non-volatile memory functionality is achieved, but large statistical spread of resistance values and limited endurance occur

Engineering Contradiction:
ImproveenduranceVSAvoidresistance value spread
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the fundamental operating parameter from resistance-based storage to charge-based storage. The memory cell uses a floating gate electrode to store electrical charge, which modulates the threshold voltage of the transistor. This parameter change from resistance to charge/threshold voltage eliminates the statistical spread issue inherent in TMO materials while achieving non-volatile memory functionality with improved endurance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite structure combining a MOS transistor with a floating gate electrode made of different materials (e.g., polysilicon, metal). This composite approach integrates the reliability of CMOS transistors with the non-volatile storage capability of the floating gate, overcoming the limitations of single-material TMO-based memory devices.

Inventive Principle:
Principle #40Composite materials

2Adaptability or versatility

If programmable logic devices with memory and logic elements are used, then flexibility and re-programmability are achieved, but power consumption increases and area efficiency decreases

Engineering Contradiction:
Improvere-programmabilityVSAvoidpower consumption
Core Design Contradiction:
Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent merges the memory element and logic element into a single integrated structure using non-volatile CMOS technology. The floating gate transistor serves both as a memory cell and as a programmable logic element, eliminating the need for separate memory and logic components. This merging reduces area overhead and power consumption while maintaining re-programmability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The non-volatile CMOS transistor with floating gate serves multiple functions: it acts as a memory element for data storage, a logic element for computation, and a programmable element for configuration. This multi-functionality allows a single device type to replace multiple specialized components, improving area efficiency and reducing overall power consumption.

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

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 programmable element achieves clear distinguishability of states, improved robustness against material parameter variations, higher current densities, and enhanced energy efficiency, enabling higher information density and functionality per area in memory and logic circuits.

Implementation Method 1

a transition-metal oxide with mobile ions that are capable of drifting under an applied electric field

Methodology Applied
Scientific EffectIon drift: Electrophoresis

Implementation Method 2

an interface of a source and/or drain electrode material and the transition metal oxide base material forms an energy barrier for electron injection from the electrode into the base material and the energy barrier depends on a concentration of the mobile ions of the base material

Methodology Applied
Scientific EffectSchottky barrier modulation: Electrical Resistance

Data Source

PatentUS8470676B2Programmable element, and memory device or logic circuit
Publication Date: 2013.06.25 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD
  • US8470676B2 patent drawing
  • US8470676B2 patent drawing
  • US8470676B2 patent drawing

AI summary

A multi-terminal programmable element. The programmable element includes a source electrode and a drain electrode on a base. The programmable element includes reference voltage contact that is not in contact with the source or drain electrode. The base includes a transition-metal oxide with oxygen vacancies for drifting under an applied electric field. Further, materials of the source electrode and the base are selected such that an interface of a source and/or drain electrode material and the transition metal oxide base material forms an energy barrier for electron injection from the electrode into the base material. The energy barrier has a height that depends on an oxygen vacancy concentration of the base material. Four non-volatile states are programmable into the programmable element.