Adaptive Soft Programming for Non-Volatile Memory Using Temperature Sensor

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Solution Overview

Problem

The existing erase operation in non-volatile memory technologies results in increased column leakage due to over-erased memory cells, particularly as feature sizes decrease, leading to failed program and read operations, and the soft programming procedure consumes a significant portion of the erase time.

Innovation Solution

Incorporating a temperature sensor to dynamically adjust the soft program gate voltage based on temperature data, using lower voltages at lower temperatures and higher voltages at higher temperatures to expedite the soft programming process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the soft programming procedure is performed to reduce column leakage from over-erased cells, then the reliability of program and read operations is improved, but the total erase operation time increases significantly

Engineering Contradiction:

Improveprogram and read operation reliabilityVSAvoiderase operation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the soft program gate voltage adjustable rather than fixed. The voltage is dynamically modified based on detected temperature conditions, allowing the system to adapt the programming parameters in real-time. This enables faster erase operations at higher temperatures while maintaining reliability, thus reducing the time penalty associated with soft programming.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the voltage parameter of the soft programming procedure based on temperature detection. By detecting the temperature and selecting from multiple voltage levels, the system optimizes the programming voltage to achieve the desired compression of threshold voltage distribution more quickly, thereby reducing the overall erase time while maintaining program and read operation reliability.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If memory cells are further scaled to increase density, then the storage capacity is improved, but the column leakage increases due to over-erased cells

Engineering Contradiction:

Improvememory storage capacityVSAvoidcolumn leakage

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent implements feedback by detecting the temperature during the erase operation and using this information to adjust the soft program gate voltage. This closed-loop approach ensures that the voltage applied during soft programming is optimized for the current thermal conditions, effectively compressing the threshold voltage distribution and reducing column leakage from over-erased cells in scaled memory structures.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent performs preliminary temperature detection before executing the soft programming procedure. This preliminary action allows the system to pre-determine the appropriate voltage level for soft programming, ensuring that the threshold voltage distribution is properly compressed before the actual programming operation, thereby preventing excessive column leakage in scaled memory cells.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If a fixed soft program gate voltage is used during erase operations, then the device complexity is reduced, but the erase operation time increases at higher temperatures

Engineering Contradiction:

Improvevoltage control complexityVSAvoidsoft programming time

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The patent transitions from a static fixed voltage approach to a dynamic temperature-dependent voltage selection. By incorporating temperature detection and using the detected temperature to select from multiple voltage levels, the system achieves faster erase operations at higher temperatures while adding minimal complexity through a straightforward temperature-to-voltage mapping mechanism.

Inventive Principle:

Principle #15Dynamics

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 reduces the time required for the soft programming procedure by effectively managing the soft program gate voltage with temperature, thereby minimizing column leakage and ensuring successful program and read operations.

Implementation Method 1

a temperature sensor to provide temperature data

Methodology Applied

Scientific EffectTemperature sensing:

Implementation Method 2

a Fowler-Nordheim (FN) erase procedure to lower the threshold voltages

Methodology Applied

Scientific EffectFowler-Nordheim tunneling:

Implementation Method 3

A soft program procedure may be used after the FN erase procedure to compress the distribution of the erased cells so as to reduce the column leakage

Methodology Applied

Scientific EffectSoft programming:

Data Source

PatentUS9129700B2Systems and methods for adaptive soft programming for non-volatile memory using temperature sensor

Publication Date: 2015.09.08 NXP USA INC

AI summary

Erasing of a non-volatile memory (NVM) having an array of bit cells includes soft programming after an initial erasing of the bit cells. Over-erased bit cells are determined. A temperature is detected. A first soft program gate voltage based on the temperature is provided. Soft programming on the over-erased bit cells using the first soft program gate voltage is performed. Any remaining over-erased bit cells are identified. if there are any remaining over-erased bit cells, soft programming is performed on the remaining over-erased bit cells using a second soft program gate voltage incremented from the first soft program gate voltage.