Flash Memory Configurable as Read-Only via OTP and SFROM Bits

Solution Overview

Problem

Existing flash memory devices cannot operate as read-only memory devices or be partitioned in real time to provide a variable flash memory portion and a variable read-only memory portion.

Innovation Solution

A flash memory device is configured to operate as a read-only memory device by incorporating a ROM-enable portion that allows sectors to be designated as read-only or multiple-time programmable, using OTP bits and SFROM-bits to control access and programming capabilities, enabling dynamic partitioning between flash and read-only memory arrays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If flash memory device is used as read-only memory device, then data security is improved, but programming flexibility is lost

Engineering Contradiction:

Improvedata securityVSAvoidprogramming flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The memory device enables dynamic configuration where sectors can be programmatically designated as read-only or multiple-time programmable through OTP bits and SFROM-bits. This allows the device to adapt its functionality based on data importance, providing both security for critical data and flexibility for other data within the same device.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

Different sectors of the flash memory device are assigned different access characteristics. Some sectors are designated as read-only for secure storage of important information, while other sectors remain multiple-time programmable. This local differentiation resolves the contradiction by applying read-only protection only where needed rather than uniformly across the entire device.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If flash memory device is partitioned into variable flash portion and variable ROM portion, then functionality is improved, but device complexity is increased

Engineering Contradiction:

ImprovefunctionalityVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The flash memory device incorporates multiple functions within a single device architecture. It can operate as pure flash memory, pure read-only memory, or a hybrid of both. The same physical memory cells can be configured to provide different functionality based on the designation bits, eliminating the need for separate devices for different memory types.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges flash memory and read-only memory functionalities into a single device. By combining the programming capabilities of flash memory with the security features of read-only memory in one integrated device, the overall system complexity is reduced compared to using multiple separate devices.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If sectors are designated as read-only, then data protection is improved, but write capability is reduced

Engineering Contradiction:

Improvedata protectionVSAvoidwrite capability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The memory device enables dynamic configuration where sectors can be programmatically designated as read-only or multiple-time programmable through OTP bits and SFROM-bits. This allows the device to adapt its functionality based on data importance, providing both security for critical data and flexibility for other data within the same device.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

Different sectors of the flash memory device are assigned different access characteristics. Some sectors are designated as read-only for secure storage of important information, while other sectors remain multiple-time programmable. This local differentiation resolves the contradiction by applying read-only protection only where needed rather than uniformly across the entire device.

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

Enables the use of flash memory devices as read-only memory devices, allowing for secure storage of important information and flexible configuration of memory arrays, ensuring that sensitive data is not inadvertently erased or modified.

Implementation Method 1

The cell 10 is erased, through a Fowler-Nordheim tunneling mechanism, by applying a high voltage on the erase gate 28 with other terminals equal to zero volt.

Methodology Applied

Scientific EffectFowler-Nordheim tunneling:

Implementation Method 2

The cell 10 is programmed, through a source side hot electron programming mechanism, by applying a high voltage on the coupling gate 26, a high voltage on the source line 14, a medium voltage on the erase gate 28, and a programming current on the bit line 20.

Methodology Applied

Scientific EffectHot electron programming:

Data Source

PatentEP3259758B1Flash memory device configurable to provide read only memory functionality

Publication Date: 2019.08.07 SILICON STORAGE TECHNOLOGY INC

Figure 1
Figure 2
Figure 3

AI summary

The disclosed embodiments comprise a flash memory device that can be configured to operate as a read only memory device. In some embodiments, the flash memory device can be configured into a flash memory portion and a read only memory portion.