Corrective Read Voltage Signals for Partially Programmed Memory Blocks
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Solution Overview
Problem
During read operations on partially programmed blocks in memory systems, errors occur due to lower threshold voltages in partially programmed blocks when using the same sensing signals as for fully programmed blocks, leading to increased peak and average Icc (current consumption) during corrective read operations.
Innovation Solution
The implementation of a controller that performs corrective read operations by applying distinct corrective read voltage signals to target and adjacent word lines, along with applying a lower pass voltage to unselected, unprogrammed word lines, reduces peak and average Icc during these operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same sensing signals are used for fully programmed blocks and partially programmed blocks, then the read operation can be simplified, but errors occur due to lower threshold voltages in partially programmed blocks
Solution Approach 1:
The patent applies different pass voltages to different word lines based on their programming state. Specifically, a first pass voltage is applied to selected word lines while a second, different pass voltage is applied to unselected word lines. This local differentiation resolves the contradiction by tailoring the voltage signals to the specific characteristics of partially programmed blocks, ensuring accurate reading without increasing overall operational complexity.
2Reliability
If corrective read operations are performed on partially programmed blocks using standard voltages, then read errors can be corrected, but peak and average Icc (current consumption) increase
Solution Approach 1:
The patent changes the voltage parameters applied during corrective read operations based on the programming state of the block. By applying a first pass voltage to selected word lines and a second pass voltage to unselected word lines, the patent optimizes the current consumption while maintaining effective error correction. This parameter differentiation reduces unnecessary current draw compared to applying uniform high voltages to all word lines.
Data Source
AI summary
Apparatuses and methods for performing corrective read operations on a partially programmed block are provided. One example apparatus can include a controller configured to perform a corrective read operation on a target word line of a partially programmed block, wherein the corrective read operation includes applying a first corrective read voltage signal to the target word line during the corrective read operation, applying a second corrective read voltage signal to a word line adjacent to the target word line during the corrective read operation, applying a first pass voltage to a number of unprogrammed word lines of the partially programmed block during the corrective read operation, and applying a second pass voltage to a first number of programmed word lines of the partially programmed block that are nonadjacent to the target word line during the corrective read operation.