Temperature-Compensated Word Line Voltage for Flash Memory Read Errors
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Solution Overview
Problem
Variations in temperature cause errors in semiconductor memory devices during data read operations due to changes in threshold voltage of flash memory cells, leading to increased error bits and potential failures.
Innovation Solution
A semiconductor memory device with a word line voltage application unit that includes a temperature detector, lookup tables for temperature compensation, and a compensator to generate and apply temperature-compensated read and pass voltages to selected and unselected word lines, reducing errors by compensating for temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature compensation is not performed, then device complexity is reduced, but data read reliability deteriorates due to threshold voltage variation
Solution Approach 1:
The patent applies temperature compensation in advance by detecting temperature and selecting appropriate read voltages from lookup tables before the actual read operation. This preliminary action ensures that the threshold voltage variation due to temperature is compensated beforehand, improving data read reliability without adding complex real-time adjustment mechanisms.
Solution Approach 2:
The patent uses lookup tables that store pre-calibrated read voltage values corresponding to different temperature ranges. Instead of performing complex calculations during operation, the system copies the appropriate voltage value from the lookup table based on detected temperature, simplifying the device complexity while maintaining reliability.
2Measurement precision
If temperature-compensated voltages are applied to all word lines, then data read accuracy is improved, but energy consumption increases
Solution Approach 1:
The patent applies temperature-compensated voltages selectively only to the selected word line where read operations are actually performed, rather than applying compensation voltages to all word lines uniformly. This local approach maintains data read accuracy for the active memory cells while minimizing unnecessary energy consumption from inactive word lines.
Solution Approach 2:
The patent applies temperature compensation partially - only to the extent necessary for the selected word line during read operations. By using pass voltages for unselected word lines and full temperature-compensated read voltages only for the selected word line, the system achieves sufficient measurement precision without the excessive energy consumption that would result from applying full compensation to all word lines.
Data Source
AI summary
A semiconductor memory device configured to apply a temperature-compensated word line voltage to a word line during a data read operation includes a memory cell array including a plurality of word lines, a plurality of non-volatile memory cells connected to the word lines, and a word line voltage application unit configured to apply a temperature-compensated read voltage to a selected word line and to apply a temperature-compensated pass voltage to at least one unselected word line during a read operation.