Selective Retired Wordline Programming for Charge-Loss Control
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Solution Overview
Problem
Programming retired wordlines in memory devices leads to negative pillar potential regions and charge loss migration, affecting active data wordlines, resulting in increased error rates and reduced performance due to the need for dummy data programming, which consumes time and system resources.
Innovation Solution
Program specific data patterns in selected retired wordlines adjacent to active data wordlines, using median and high threshold voltage levels to mitigate negative pillar potential and charge loss, reducing the number of programmed retired wordlines to improve performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all retired wordlines are programmed with dummy data, then charge loss migration and negative pillar potential are mitigated, but programming time and system resources are consumed
Solution Approach 1:
Instead of uniformly programming all retired wordlines, the patent applies local quality by selectively programming only boundary retired wordlines (those adjacent to active data wordlines) while skipping inner retired wordlines. This localized approach concentrates the protective programming action where it is most needed—at the boundaries where charge loss migration and negative pillar potential effects are most severe—while avoiding the time cost of programming all retired wordlines uniformly.
2Productivity
If retired wordlines are not programmed, then programming time is saved, but negative pillar potential regions and charge loss migration affect active data wordlines
Solution Approach 1:
The patent extracts the harmful effect (negative pillar potential and charge loss migration) from the entire retired wordline array and isolates it to specific boundary locations. By programming only the boundary retired wordlines, the solution extracts and addresses the harmful effects only where they originate and propagate, rather than attempting to eliminate them throughout the entire memory array. This selective extraction reduces the scope of the problem while maintaining effectiveness.
3Reliability
If a large number of retired wordlines are programmed, then protection against charge loss is improved, but system resources and power consumption increase
Solution Approach 1:
The patent applies partial action by programming only a subset of retired wordlines (specifically boundary wordlines) rather than all retired wordlines. This partial programming approach provides sufficient protection against charge loss migration and negative pillar potential at the critical boundary locations without the excessive energy consumption that would result from programming every retired wordline in the array. The action is precisely calibrated to address the problem where it matters most.
Data Source
AI summary
A memory device comprises an array of memory cells organized into a plurality of wordlines, and a processing device to perform processing operations that receive a program command specifying a memory unit and data comprising first received data, where the plurality of wordlines includes one or more first active data wordlines and a group of consecutive retired wordlines. The processing operations also program the specified data to the memory unit by programming the first received data to the one or more first active data wordlines, identifying a first retired boundary wordline that is in the group of consecutive retired wordlines and is adjacent to one of the first active data wordlines, generating a first data pattern comprising a first plurality of threshold voltage levels, and programming the first data pattern to the first retired boundary wordline.