Dummy Word Line Control for Non-Volatile Memory

Solution Overview

Problem

In non-volatile semiconductor memory devices, program disturb occurs when unintended memory cells receive programming voltage, leading to data errors due to incomplete inhibition of memory cells not meant to be programmed.

Innovation Solution

The implementation of a memory system that includes data memory cells and dummy memory cells, where a gate voltage based on temperature is applied to dummy memory cells as part of memory operations to mitigate program disturb, with the word line voltage adjusted according to temperature to prevent unwanted programming of data memory cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If program voltage is applied to a selected word line to program memory cells, then programming speed is improved, but program disturb occurs in unintended memory cells

Engineering Contradiction:

Improveprogramming speedVSAvoiddata integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent segments the memory array into data memory cells and dummy memory cells, with dummy cells strategically positioned adjacent to selected data cells. This segmentation allows the system to apply program voltage to the selected word line while using dummy cells to absorb or shield against voltage leakage, thereby preventing program disturb in unintended data cells while maintaining fast parallel programming of selected cells.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Dummy memory cells serve as intermediary elements between the program voltage application and the data memory cells. These dummy cells act as a buffer or mediator that intercepts stray electric fields and voltage leakage, preventing them from affecting unintended data cells. The dummy cells are specifically positioned to provide this protective intermediary function during programming operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If all memory cells connected to a word line are programmed concurrently, then programming efficiency is improved, but unintended memory cells cannot be inhibited from programming

Engineering Contradiction:

Improveprogramming efficiencyVSAvoidprogramming precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent segments the memory array into data memory cells and dummy memory cells, with dummy cells strategically positioned adjacent to selected data cells. This segmentation allows the system to apply program voltage to the selected word line while using dummy cells to absorb or shield against voltage leakage, thereby preventing program disturb in unintended data cells while maintaining fast parallel programming of selected cells.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by giving different functional roles to different parts of the memory array. Data memory cells are designed for data storage and programming, while dummy memory cells are specifically designed to provide protection against program disturb. This local differentiation in function allows the system to maintain high programming efficiency across the array while ensuring precision in controlling which cells are actually programmed.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS9852803B2Dummy word line control scheme for non-volatile memory

Publication Date: 2017.12.26 SANDISK TECHNOLOGIES LLC

AI summary

A memory system includes blocks (or other groupings) of memory cells including data memory cells and dummy memory cells. In order to mitigate program disturb or other issues, the memory system applies a gate voltage based on temperature to all or a subset of the dummy memory cells as part of a memory operation.