Non-Volatile Memory Characterization via Current Sensing
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Solution Overview
Problem
The existing methods for testing non-volatile memory are time-consuming and costly due to the need to measure and characterize each memory cell individually, especially in large memory arrays.
Innovation Solution
A method and system for characterizing non-volatile memory cells by applying a first voltage to a word line and measuring the current flowing through the cells using a sense amplifier, which compares the measured current with adjustable reference currents to determine the cell characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If each memory cell is individually measured and characterized to determine read parameters and write parameters, then measurement precision is improved, but test time increases significantly
Solution Approach 1:
The patent segments the memory array into rows and columns, allowing systematic measurement of memory cells by selecting specific rows and columns. This segmentation enables efficient measurement approaches where entire rows or columns can be measured simultaneously rather than individual cells, reducing test time while maintaining measurement precision through controlled selection of measurement targets.
Solution Approach 2:
The patent changes the measurement parameter from voltage-based threshold measurement to current-based measurement. By measuring the current flowing through memory cells during read operations and using this current information to determine cell characteristics, the patent achieves accurate cell characterization without the time-consuming voltage sweeping required by traditional threshold measurement methods.
2Measurement precision
If traditional measurement methods are used to characterize each bit cell, then measurement accuracy is maintained, but device complexity increases due to high-voltage circuitry requirements
Solution Approach 1:
The patent extracts the high-voltage generation circuitry from the memory device by performing measurements during normal read operations at standard voltages. The cell characterization is achieved by measuring currents during regular read operations and processing this data to determine cell thresholds, eliminating the need for separate high-voltage measurement circuits while maintaining characterization accuracy.
Solution Approach 2:
The patent makes the read operation circuitry multi-functional by using the same sense amplifiers and current measurement circuits that operate during normal memory reads to perform cell characterization measurements. This universal use of existing circuitry eliminates the need for dedicated high-voltage measurement equipment, reducing device complexity while maintaining measurement precision.
3Measurement precision
If individual cell measurement is performed for large memory arrays, then measurement completeness is improved, but productivity decreases due to increased test cost and time
Solution Approach 1:
The patent implements periodic measurement cycles where entire rows or columns of memory cells are measured in sequence during normal read operations. By systematically cycling through different rows and columns and accumulating measurement data over multiple operation cycles, the patent achieves complete cell characterization for large memory arrays without requiring dedicated measurement time for each cell, thereby maintaining measurement completeness while improving test efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for faster and more efficient characterization of non-volatile memory cells by grounding the word lines during testing, reducing the need for high-voltage circuitry and thereby decreasing test time and cost.
Implementation Method 1
measuring a current flowing through the non-volatile memory cell in response to applying the first voltage
Data Source
AI summary
In accordance with an embodiment, a method for characterizing a non-volatile memory, includes: applying a first voltage on a word line conductively coupled to a non-volatile memory cell and measuring a current flowing through the non-volatile memory cell in response to applying the first voltage. Measuring the current includes: using a sense amplifier, comparing the current flowing through the non-volatile memory cell with a plurality of different first currents generated by an adjustable current source while applying the same first voltage on the word line, and determining the measured current based on the comparing.