Non-volatile Memory Dummy Word Line Current Control
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Solution Overview
Problem
In semiconductor memory systems, power consumption during the program-verify operation is higher than preferred, particularly due to peak current fluctuations associated with word line dependencies, which complicates optimization for reduced power usage while maintaining performance.
Innovation Solution
The introduction of dummy memory cells connected to a dummy word line, programmed to specific threshold voltages based on the position of the data word line, to increase resistance and lower peak current, thereby reducing power consumption during program-verify operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If dummy memory cells connected to a dummy word line are programmed to specific threshold voltages, then peak current is lowered and power consumption is reduced, but device complexity increases
Solution Approach 1:
The memory array is segmented into data memory cells and dummy memory cells, with the dummy cells serving a specialized function of providing controlled resistance. This segmentation allows the system to address peak current issues without complicating the entire memory structure, as only a portion of the array is modified.
Solution Approach 2:
Dummy memory cells act as an intermediary element between the word line and the data memory cells. By programming these dummy cells to specific threshold voltages, they provide a controlled resistance that mediates the peak current flow, thereby reducing power consumption during program-verify operations without directly modifying the data storage cells.
2Productivity
If dummy memory cells are programmed to different threshold voltages based on data word line position, then channel resistance is maintained constant and power efficiency is optimized, but manufacturing precision requirements increase
Solution Approach 1:
Different regions of the memory array, corresponding to different data word line positions, are assigned different threshold voltages for the dummy memory cells. This local quality approach ensures that each region has the optimal resistance characteristics for its specific position, maintaining constant channel resistance across the entire array while optimizing power efficiency for each local region.
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 effectively lowers peak and average power consumption by maintaining constant channel resistance across data word lines, addressing the word line dependency issue and optimizing power efficiency during programming.
Implementation Method 1
The introduction of dummy memory cells connected to a dummy word line, programmed to specific threshold voltages based on the position of the data word line, to increase resistance and lower peak current
Data Source
AI summary
In order to lower the peak and average current through the channel (thereby lowering peak and average power consumption) during program-verify, which exhibits a word line dependency, the inventors propose to program dummy memory cells connected to a dummy word line before programming data memory cells connected to a data word line. The additional resistance in the NAND string introduced by the preprogrammed dummy memory cells will cause the peak current, and power consumption, to be lower. To address the word line dependency, the dummy memory cells connected to the dummy word line can be programmed to different threshold voltages based on which data word line is to be programmed. Thus, prior to programming data non-volatile memory cells connected to a particular data word line, the dummy memory cells are programmed to a threshold voltage that is chosen based on the position of the particular data word line.