Adaptive Negative Wordline Voltage for Lifetime Data Retention
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Solution Overview
Problem
Non-volatile memory devices face challenges in maintaining data retention degradation (DR) across different stages of their product lifetime, particularly due to aggressive scaling and process changes that impact DR degradation at both the beginning-of-life (BOL) and end-of-life (EOL) stages, leading to issues with vertical data retention and uncorrectable errors.
Innovation Solution
An adaptive negative wordline (NWL) scheme is implemented to adjust negative wordline settings based on the product lifetime stage, optimizing DR degradation by shifting Vth distributions for both BOL and EOL stages, thereby reducing errors and improving memory performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aggressive scaling and process changes are implemented to improve memory density and performance, then productivity and manufacturing capability are improved, but data retention degradation worsens at both BOL and EOL stages
Solution Approach 1:
The patent implements dynamic adjustment of the negative wordline voltage parameter based on the product lifetime stage. The controller adapts the NWL setting from a first setting at BOL to a second setting at EOL, allowing the system to optimize data retention characteristics for each stage while maintaining high-density memory operation. This dynamic parameter adjustment resolves the contradiction by making the memory system adaptable to aging effects without sacrificing the benefits of aggressive scaling.
Solution Approach 2:
The patent changes the electrical parameter (negative wordline voltage) based on the operational stage of the memory device. By adjusting the NWL voltage from a first value at BOL to a second value at EOL, the system compensates for degradation mechanisms that occur over time. This parameter change strategy allows the memory to maintain reliable data retention despite aggressive scaling, as the electrical characteristics are optimized for each lifecycle stage.
2Device complexity
If a fixed negative wordline setting is used throughout the product lifetime, then device complexity is reduced, but data retention performance deteriorates at EOL stage
Solution Approach 1:
The patent introduces dynamic adaptation of the negative wordline setting based on the determined product lifetime stage. The controller transitions from a static control approach to a dynamic one, where the NWL parameter is adjusted according to whether the memory is at BOL or EOL. This dynamic control mechanism improves EOL data retention while maintaining relatively simple device architecture, as the adaptation is managed through control logic rather than hardware complexity.
Solution Approach 2:
The patent implements a feedback mechanism where the controller determines the product lifetime stage and adjusts the negative wordline setting accordingly. This feedback loop allows the system to automatically compensate for aging effects by selecting appropriate NWL settings for each operational phase. The feedback-based approach maintains reliability at EOL without requiring complex hardware modifications, as the adaptation is achieved through intelligent control.
3Reliability
If negative wordline voltage is adjusted to improve data retention at EOL, then reliability is improved, but device complexity increases due to adaptive control mechanisms
Solution Approach 1:
The patent implements dynamic adjustment of the negative wordline voltage based on the determined product lifetime stage. By adapting the NWL setting from a first value at BOL to a second value at EOL, the system improves data retention reliability while managing complexity through controlled adaptation rather than hardware redundancy. The dynamic parameter adjustment allows a single memory device to optimize performance across its entire lifecycle.
Solution Approach 2:
The patent changes the electrical parameter (negative wordline voltage) based on the operational stage to improve reliability. By adjusting the NWL voltage setting according to the product lifetime stage, the system compensates for degradation without requiring complex hardware architectures. The parameter change strategy achieves improved EOL retention through software/firmware-controlled voltage adjustment rather than additional physical components.
Data Source
AI summary
A storage device comprises: a non-volatile memory including control circuitry and an array of memory cells formed using a set of word lines and a set of bit lines. A controller, coupled to the non-volatile memory, configured to: determine, based on a stage of a product lifetime of the non-volatile memory, a negative word line setting for implementing during performance of a first operation; perform the first operation, the first operation including adjusting, based on the negative word line setting, a negative word line relative parameter; determine, based on another stage of the product lifetime of the non-volatile memory, another negative word line setting for implementing during performance of a second operation; and perform the second operation, the second operation including adjusting, based on the other negative word line setting, another negative word line relative parameter.