NAND Flash Burst Programming via Continuous Charge Pump
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Solution Overview
Problem
Current NAND flash memory programming techniques are inefficient, particularly in reducing the time required to program flash memory cells, which affects overall performance and can lead to data loss in scenarios like sudden power outages.
Innovation Solution
The implementation of a fast SLC burst program sequence that maintains a voltage pump in an ON state and overlaps the transfer of next page data with the wordline/bitline discharge during programming, eliminating the need for charge pump reset and charge-up time between operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional programming sequences are used with charge pump reset between operations, then reliability is maintained, but programming time increases
Solution Approach 1:
The charge pump is activated in advance and maintained in an ON state before programming operations begin, eliminating the need for repeated charge-up cycles. This preliminary preparation of the voltage supply system reduces subsequent programming time while maintaining reliable operation throughout the burst sequence.
Solution Approach 2:
The charge pump operates continuously during the entire burst programming sequence without interruption or reset, maintaining continuous useful action. This eliminates idle time between programming operations while the system monitors completion status, ensuring both speed and reliability.
2Productivity
If burst programming is implemented to reduce time, then productivity increases, but complexity of control increases
Solution Approach 1:
A completion status bit is monitored to provide feedback on whether programming has finished. This simple feedback mechanism allows the system to execute burst programming sequences efficiently without complex control logic, as the completion status automatically signals when the operation is complete and the next sequence can begin.
3Productivity
If programming speed is increased through burst modes, then productivity improves, but energy consumption increases
Solution Approach 1:
The charge pump operates continuously at a steady state during burst programming, avoiding the energy-wasting repeated charge-up and reset cycles. This continuous operation maintains optimal energy efficiency while achieving high programming speeds throughout the burst sequence.
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 significantly reduces the total programming time, enhancing flash memory performance, especially for large data chunks, and ensures data integrity by preventing data loss during power outages without the need for excessive holdup capacitors.
Implementation Method 1
Fowler-Nordheim (FN) tunneling or hot carrier injection (HCI) techniques may be employed to apply or remove charge
Implementation Method 2
Fowler-Nordheim (FN) tunneling or hot carrier injection (HCI) techniques may be employed to apply or remove charge
Data Source
AI summary
A fast burst program sequence that reduces overall NAND flash programming time is disclosed. The burst program sequence includes maintaining a charge pump in an ON state and not fully discharging the WL/BLs at the conclusion of the programming phase of each program operation. As a result, the fast burst program sequence provides total program time savings over an existing cache program sequence by eliminating the full WL/BL discharge and charge pump reset that conventionally occurs after each program operation, which in turn, allows for the transfer of next page data from the page buffer to the data latches to be hidden within the program time of a prior/current program operation.