Dielectric Sheet Measurement Using SCM Reference Capacitors
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Solution Overview
Problem
Scanning capacitance microscopy is unable to accurately measure the dielectric constant of dielectric sheets due to measurement errors caused by shape variations and internal voids in the sample.
Innovation Solution
A method using a semiconductor capacitor connected in series with three parallel plate capacitors, each with known dielectric constants and thicknesses, to calculate the dielectric constant by measuring scanning capacitance microscopy signals and impedance ratios, thereby compensating for shape-induced errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the dielectric resonance method is used to measure the dielectric constant, then the dielectric constant can be obtained through resonance frequency measurement, but measurement errors are introduced due to shape variations and internal voids in the sample
Solution Approach 1:
The patent introduces a reference capacitor with a reference dielectric sheet as an intermediary standard. By comparing the impedance of the test dielectric sheet against the known reference dielectric sheet through scanning capacitance microscopy, the measurement becomes relative rather than absolute, eliminating the need for resonance frequency measurements that are sensitive to sample shape and internal voids.
Solution Approach 2:
The patent replaces the electromagnetic resonance measurement system with a scanning capacitance microscopy system. Instead of measuring resonance frequency in an electromagnetic field, the system uses a conductive probe to measure capacitance variations at the nanoscale, substituting a direct electrical measurement approach for the indirect resonance-based method.
2Adaptability or versatility
If scanning capacitance microscopy is used to analyze semiconductor materials, then electrical properties such as carrier concentration distribution can be observed, but the dielectric constant of dielectric sheets cannot be measured
Solution Approach 1:
The patent extends the application of scanning capacitance microscopy beyond semiconductor material analysis to include dielectric constant measurement of dielectric sheets. By establishing a comparison method using reference and test capacitors, the same SCM instrument can perform multiple functions: analyzing semiconductor electrical properties and measuring dielectric constants, thereby achieving multi-functionality.
Solution Approach 2:
The patent changes the measurement parameter from capacitance-only analysis to impedance ratio analysis. By measuring the ratio of impedances between reference and test capacitors, and incorporating the known dielectric constant and thickness parameters of the reference sheet, the system can calculate the dielectric constant of the test sheet, thus enabling new measurement capabilities through parameter transformation.
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
The method accurately determines the dielectric constant of dielectric sheets, enhancing the capabilities of scanning capacitance microscopy by reducing measurement errors from surface undulations and internal voids.
Implementation Method 1
connecting a semiconductor capacitor and a first parallel plate capacitor in series
Implementation Method 2
applying a modulation voltage to the semiconductor capacitor and the first parallel plate capacitor to periodically change a width of the depletion region
Implementation Method 3
calculating an impedance ratio based on the first scanning capacitance microscopy signal, the second scanning capacitance microscopy signal, and (d2/d1)×(ε1/ε2)
Data Source
Figure 1(a)
Figure 1(b)
Figure 1(c)
AI summary
In a method for obtaining the dielectric constant of a dielectric sheet, a modulation voltage is applied to a semiconductor capacitor and a first parallel plate capacitor to measure a first scanning capacitance microscopy signal. Then, the first parallel plate capacitor is replaced with a second parallel plate capacitor to measure a second scanning capacitance microscopy signal corresponding to the semiconductor capacitor and the second parallel plate capacitor. Finally, the second parallel plate capacitor is replaced with a third parallel plate capacitor to measure a third scanning capacitance microscopy signal corresponding to the semiconductor capacitor and the third parallel plate capacitor. Based on the scanning capacitance microscopy signals and dielectric constants and the equivalent physical thicknesses of the dielectric sheets of the first parallel plate capacitor and second parallel plate capacitor, the dielectric constant of the dielectric sheet of the third parallel plate capacitor is obtained.