Charge Storage Layer Refractive Index via Memory Cell Breakdown Voltage
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Solution Overview
Problem
Existing methods do not effectively measure the refractive index of charge storage layers in semiconductor memory devices, which affects the classification and reliability of semiconductor memory devices.
Innovation Solution
A method is developed to measure the refractive index of charge storage layers by determining the positive and negative breakdown voltages of memory cells, and classifying the semiconductor memory device based on these measurements, dividing cells into lower and upper groups, and comparing refractive indices with reference values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing measurement methods are used, then the measurement process is simple, but the refractive index of charge storage layers cannot be effectively measured
Solution Approach 1:
The patent introduces an intermediary relationship between breakdown voltage measurement and refractive index determination. By measuring breakdown voltage (a readily obtainable electrical parameter) and using it to infer refractive index through established relationships, the method enables indirect measurement of refractive index without requiring direct optical measurement equipment on the charge storage layer.
Solution Approach 2:
The patent replaces direct optical measurement methods with electrical measurement methods. Instead of using optical systems to directly measure refractive index, the method uses electrical breakdown voltage measurements to determine refractive index, substituting a mechanical/electrical system for an optical measurement system.
2Measurement precision
If breakdown voltage measurement method is used, then refractive index can be determined, but measurement time increases due to multiple voltage measurements
Solution Approach 1:
The patent performs preliminary classification by measuring only certain representative memory cells rather than all cells. By selecting specific cells for breakdown voltage measurement and using their refractive indices to represent broader groups, the method reduces total measurement time while maintaining acceptable accuracy for product classification purposes.
Solution Approach 2:
The patent applies partial measurement by measuring breakdown voltage of selected memory cells rather than all cells in the device. This partial action is sufficient for obtaining representative refractive index values needed for product group classification, achieving the necessary measurement precision without the time cost of complete measurement.
3Reliability
If all memory cells are measured, then comprehensive data is obtained, but processing complexity and time increase
Solution Approach 1:
The patent performs preliminary selection of representative memory cells for measurement before conducting the actual breakdown voltage measurements. By pre-identifying which cells to measure based on their representativeness for different product groups, the method ensures reliable classification data is obtained from a manageable subset rather than requiring exhaustive measurement of all cells.
Solution Approach 2:
The patent uses partial measurement of selected memory cells to achieve sufficient reliability for product classification. The measurements on representative cells provide adequate statistical basis for classification without the excessive time and processing requirements of measuring every cell in the device.
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
Enables accurate classification of semiconductor memory devices into product groups with varying data reliability, improving the quality and performance of the devices by optimizing the charge storage layer deposition process.
Implementation Method 1
the charge storage layer may have a first refractive index when a first amount of electrons are trapped in the charge storage layer
Implementation Method 2
the charge storage layer may have a second refractive index when a second amount of holes are trapped in the charge storage layer
Implementation Method 3
the charge storage layer may have different refractive indices depending on an amount of charges trapped in the charge storage layer
Data Source
AI summary
Provided herein is a method of measuring a refractive index of a semiconductor memory device and a method of classifying a product group of a semiconductor memory device using the same. The method of measuring a refractive index of a semiconductor memory device includes measuring a positive breakdown voltage and a negative breakdown voltage of each of memory cells coupled to a selected word line. The method also includes checking a refractive index of a charge storage layer of each of the memory cells based on the measured positive breakdown voltage and the measured negative breakdown voltage.