Pre-conditioning Waveforms for Non-Volatile Storage Read Accuracy
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Solution Overview
Problem
Non-volatile storage devices face challenges in accurately reading programming states due to noise from trap sites, particularly 1/f noise, which affects the reliability of stored data, especially as storage elements are scaled down.
Innovation Solution
The method involves applying pre-conditioning waveforms before read operations to stabilize the short-term history of storage elements, allowing for iterative probabilistic decoding using reliability metrics derived from multiple read operations to improve data decoding accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple read operations are performed to improve decoding accuracy, then reliability is improved, but loss of time increases
Solution Approach 1:
The patent applies pre-conditioning waveforms before read operations to stabilize the short-term history of storage elements. This preliminary action reduces the impact of 1/f noise and trap site effects during subsequent read operations, improving decoding accuracy without requiring excessive multiple reads, thus balancing reliability improvement with time loss reduction.
Solution Approach 2:
The patent uses reliability metrics derived from multiple read operations to iteratively improve decoding accuracy. The feedback mechanism involves using the results of initial read operations to adjust subsequent read operations and decoding processes, optimizing the balance between time spent on reading and accuracy achieved.
2Reliability
If pre-conditioning waveforms are applied to stabilize storage elements, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies pre-conditioning waveforms before read operations to stabilize the short-term history of storage elements. This preliminary action reduces the impact of 1/f noise and trap site effects during subsequent read operations, improving decoding accuracy without requiring excessive multiple reads, thus balancing reliability improvement with time loss reduction.
Solution Approach 2:
The patent modifies control waveform parameters (amplitude, duration, timing) of pre-conditioning waveforms to optimize their effect on storage element stabilization. By carefully tuning these parameters, the system achieves reliable reading while controlling the complexity of the control mechanism.
3Reliability
If iterative probabilistic decoding is used to improve state determination accuracy, then reliability is improved, but loss of time increases
Solution Approach 1:
The patent applies pre-conditioning waveforms before read operations to stabilize the short-term history of storage elements. This preliminary action reduces the impact of 1/f noise and trap site effects during subsequent read operations, improving decoding accuracy without requiring excessive multiple reads, thus balancing reliability improvement with time loss reduction.
Solution Approach 2:
The patent uses reliability metrics derived from multiple read operations to iteratively improve decoding accuracy. The feedback mechanism involves using the results of initial read operations to adjust subsequent read operations and decoding processes, optimizing the balance between time spent on reading and accuracy achieved.
Data Source
AI summary
Data stored in non-volatile storage is read using sense operations and associated pre-conditioning waveforms. The pre-conditioning waveform provides a short term history for a non-volatile element which is analogous to the conditions experienced during programming when a programming pulse is applied prior to a verify operation. The pre-conditioning waveform can cause electrons to enter and exit trap sites, for instance, so that the accuracy of a probabilistic decoding process is improved. In one approach, multiple read operations are performed, some with pre-conditioning waveforms and some without. Pre-conditioning waveforms with different characteristics, such as amplitude, shape, duration and time before the associated read pulse, can also be used. For probabilistic decoding, initial reliability metrics can be developed based on multiple reads. Tables which store the reliability metrics can then be prepared for use in subsequent decoding.