Flash Memory Programming via Overlapping Bit Line Setup

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Solution Overview

Problem

The existing flash memory programming methods face inefficiencies due to the time required to charge word lines, which increases with the number of memory cells connected, and increasing pump capacity to address this issue results in a larger chip area.

Innovation Solution

The method involves charging selection lines with a first voltage during the bit line setup interval, activating a block word line to connect these lines to corresponding word lines, and then applying a second, higher voltage to a selected selection line during the program execution interval, utilizing a circuit configuration that includes a page buffer, decoding and driving circuits, and a control logic circuit to manage these operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the pump capacity is increased to charge word lines faster, then the programming speed is improved, but the chip area increases

Engineering Contradiction:

Improveprogramming speedVSAvoidchip area

Core Design Contradiction:

SpeedVSArea of stationary object

Solution Approach 1:

The selection lines are charged with a first voltage during the bit line setup interval, before the word line enable interval begins. This preliminary charging action allows the word lines to be quickly activated without requiring a large pump capacity, as the selection lines are already prepared with the appropriate voltage level.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The programming operation is divided into two distinct intervals: a bit line setup interval for charging selection lines, and a word line enable interval for activating word lines. This segmentation allows independent optimization of each phase, enabling fast word line charging without increasing overall pump capacity by preparing selection lines in advance.

Inventive Principle:

Principle #1Segmentation

2Loss of time

If the word line charging time is reduced, then the programming speed is improved, but the pump capacity must be increased

Engineering Contradiction:

Improveword line charging timeVSAvoidpump capacity

Core Design Contradiction:

Loss of timeVSPower

Solution Approach 1:

Selection lines are charged during the bit line setup interval before the word line enable interval starts. This preliminary action stores energy in the selection lines, which is then transferred to word lines during the enable interval, reducing the instantaneous power requirement of the pump.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The selection line charging and word line enabling operations are overlapped in time, with the selection line charging occurring continuously during the bit line setup interval and transitioning into the word line enable interval. This continuous action eliminates idle time and maintains efficient power utilization.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS7486557B2Methods/circuits for programming flash memory devices using overlapping bit line setup and word line enable intervals

Publication Date: 2009.02.03 SAMSUNG ELECTRONICS CO LTD

AI summary

A method of programming a flash memory device includes charging selection lines with a first voltage while applying program data to bit lines to during a bit line setup interval, then activating a block word line to electrically connect the selection lines to corresponding word lines, and then applying a second voltage, greater than the first voltage, to a selected one of the selection lines. Related devices are also disclosed.