Heterodyne Scanning Probe Microscopy for Sub-Surface Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing acoustic scanning probe microscopy methods face limitations in resolution and contrast, particularly when imaging sub-surface structures, due to the decreasing size of semiconductor elements and the need for higher resolution imaging.
Innovation Solution
A heterodyne scanning probe microscopy method using acoustic input signals with frequencies above 1 GHz, combined with a heterodyne measurement technique, to enhance resolution and contrast by analyzing the difference frequency component of mixed acoustic signals, allowing for the detection of sub-surface structures at the micrometer and nanometer scale.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic input signals with frequencies above 1 GHz are used, then resolution and contrast of sub-surface structure detection are improved, but device complexity increases due to the need for heterodyne measurement techniques and high-frequency signal generation
Solution Approach 1:
The patent introduces a local oscillator signal as an intermediary element that mixes with the high-frequency acoustic input signal to produce a difference frequency signal. This mediator enables the detection of high-frequency acoustic waves by converting them to a lower, more manageable frequency range while preserving the structural information, thus resolving the contradiction between achieving high resolution and maintaining system simplicity
Solution Approach 2:
The patent changes the frequency parameter of the acoustic signal to above 1 GHz to improve resolution and contrast. By using heterodyne detection, the system transforms the high-frequency signal into a difference frequency that can be measured with standard equipment, allowing the parameter change to benefit measurement precision without proportionally increasing device complexity
2Manufacturing precision
If the size of semiconductor elements is decreased, then imaging resolution requirements increase, but the ability to detect and image these structures with existing acoustic methods deteriorates
Solution Approach 1:
The patent utilizes mechanical vibration in the form of high-frequency acoustic waves (above 1 GHz) to probe sub-surface structures. The acoustic waves interact with the semiconductor elements, and by detecting the scattered or reflected waves through heterodyne measurement, the system achieves the measurement precision needed to characterize increasingly smaller semiconductor features
Solution Approach 2:
The patent applies preliminary action by pre-mixing the high-frequency acoustic input signal with a local oscillator signal before detection. This preliminary heterodyne mixing converts the high-frequency signal to a difference frequency that is easier to detect and analyze, enabling the system to maintain measurement precision as semiconductor element sizes decrease
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 improves the accuracy and contrast of sub-surface structure detection, enabling the visualization of structures smaller than 5 micrometers and 50 nanometers, respectively, by leveraging the diffraction limit and non-linear interactions between the probe tip and sample surface.
Implementation Method 1
a transducer for applying an acoustic input signal to the sample
Implementation Method 2
sensing, using a probe including a probe tip in contact with the surface, an acoustic output signal, wherein the acoustic output signal is representative of acoustic waves induced by the acoustic input signal
Implementation Method 3
applying a further acoustic input signal to at least one of the probe or the sample for obtaining a mixed acoustic signal, the further acoustic input signal including at least a second signal component having a frequency above 1 gigahertz, wherein the mixed acoustic signal comprises a third signal component having a frequency equal to a difference between the first frequency and the second frequency
Data Source
AI summary
The present invention relates to a heterodyne scanning probe microscopy method for imaging structures on or below the surface of a sample, the method including applying, using a transducer, an acoustic input signal to the sample sensing, using a probe including a probe tip in contact with the surface, an acoustic output signal, wherein the acoustic output signal is representative of acoustic surface waves induced by the acoustic input signal wherein the acoustic input signal comprises at least a first signal component having a frequency above 1 gigahertz, and wherein for detecting of the acoustic output signal the method comprises a step of applying a further acoustic input signal to at least one of the probe or the sample for obtaining a mixed acoustic signal, the further acoustic input signal including at least a second signal component having a frequency above 1 gigahertz, wherein the mixed acoustic signal comprises a third signal component having a frequency equal to a difference between the first frequency and the second frequency, wherein the frequency of the third signal component is below 1 gigahertz.