Nonvolatile Memory Erasing via Body Contact Hot Hole Injection

Solution Overview

Problem

Conventional erasing methods for nonvolatile flash memory, such as Fowler-Nordheim tunneling and band-to-band hot hole effects, face issues with high erasing voltage and time, leading to retention degradation and nonuniform threshold voltage, respectively.

Innovation Solution

The method employs forward bias between the source/drain region and the body contact to inject and accelerate majority carriers, overcoming the oxide barrier to erase the memory, allowing for reduced erasing time and voltage while maintaining thicker tunnel oxide retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Fowler-Nordheim tunneling effect is used for erasing, then erasing capability is achieved, but erasing voltage and erasing time become excessively high

Engineering Contradiction:

Improveerasing capabilityVSAvoiderasing voltage

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent changes the erasing mechanism from Fowler-Nordheim tunneling to band-to-band hot hole injection by modifying the voltage application pattern. Instead of applying high voltage to the control gate, the patent applies voltage to the body contact, changing the physical mechanism of carrier injection and thereby reducing the required erasing voltage while maintaining erasing capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces the body contact as an intermediary element to facilitate carrier injection. By using the body contact as the voltage application point rather than the control gate, the patent creates a new conduction path that enables hot hole injection with lower voltage, thus resolving the contradiction between erasing capability and power consumption

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If Fowler-Nordheim tunneling effect is used for erasing, then erasing capability is achieved, but erasing time becomes excessively long

Engineering Contradiction:

Improveerasing capabilityVSAvoiderasing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent changes the erasing mechanism from Fowler-Nordheim tunneling to band-to-band hot hole injection by modifying the voltage application pattern. Instead of applying high voltage to the control gate, the patent applies voltage to the body contact, changing the physical mechanism of carrier injection and thereby reducing the required erasing voltage while maintaining erasing capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces the body contact as an intermediary element to facilitate carrier injection. By using the body contact as the voltage application point rather than the control gate, the patent creates a new conduction path that enables hot hole injection with lower voltage, thus resolving the contradiction between erasing capability and power consumption

Inventive Principle:

Principle #24Intermediary (Mediator)

3Loss of time

If band-to-band hot hole effect is used for erasing, then erasing speed is improved, but threshold voltage becomes nonuniform causing reliability issues

Engineering Contradiction:

Improveerasing timeVSAvoidthreshold voltage uniformity

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The patent applies local quality by creating different voltage conditions in different regions of the device. By applying voltage to the body contact rather than the control gate, the patent achieves localized hot hole injection that is more uniform across the channel, preventing the nonuniform threshold voltage distribution that occurs with conventional control gate-based methods

Inventive Principle:

Principle #3Local quality

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

This approach decreases erasing time and voltage, enhances retention, and maintains the reliability of nonvolatile memory by using a forward bias to inject and accelerate carriers, effectively addressing the limitations of existing methods.

Implementation Method 1

uses the forward bias between the source/drain region and the body contact to inject majority carriers (holes with N-channel) of the body contact into the body

Methodology Applied

Scientific EffectForward bias:

Implementation Method 2

accelerates the majority carriers by the electric field between the body and the gate to energize the majority carriers to overcome the oxide barrier

Methodology Applied

Scientific EffectElectric field acceleration: Electric Field

Implementation Method 3

energize the majority carriers to overcome the oxide barrier and to erase the nonvolatile memory

Methodology Applied

Scientific EffectHot hole effect:

Data Source

PatentUS7869284B1Erasing method for nonvolatile memory

Publication Date: 2011.01.11 ACER INC

AI summary

The present invention relates to an erasing method for nonvolatile memory, which uses forward bias between the source/drain region and body contact to inject majority carriers into the body, and then accelerates the majority carriers by an electric field between the body and the gate to energize the majority carriers to overcome the oxide barrier and to erase the nonvolatile memory.