Near-field Sensor Height Control via X-ray Diffraction
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Solution Overview
Problem
Near field sensors face challenges in accurately measuring distance due to the sensitivity of evanescent modes to material and three-dimensional geometry changes, requiring precise height control at the nanometer scale, which traditional measurement techniques struggle to achieve effectively.
Innovation Solution
A method involving the creation of a diffraction pattern using a coherent x-ray beam with a wavelength not exceeding 20 nanometers, detecting multiple portions of the diffraction pattern, and processing these signals to determine the slit height and subsequently the distance between the near field sensor and the substrate, utilizing a height measurement module and controller to maintain precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional optical interferometry or capacitive measurement techniques are used for height measurement, then the measurement process is simple to implement, but the measurement precision deteriorates due to sensitivity to material and geometry changes
Solution Approach 1:
The patent changes the fundamental measurement parameter from optical wavelength (hundreds of nanometers) to x-ray wavelength (less than 20 nanometers). This parameter change enables nanometer-scale height measurement precision while using diffraction pattern analysis instead of traditional optical interferometry, thereby achieving high precision without proportionally increasing system complexity
Solution Approach 2:
The patent replaces traditional optical measurement systems with an x-ray diffraction-based measurement system. By substituting optical radiation with x-ray radiation and using diffraction pattern detection instead of optical interference patterns, the system achieves superior height measurement precision that is insensitive to material and geometry variations
2Reliability
If the near field sensor operates at visible to deep UV wavelengths, then the sensor can detect evanescent modes close to the substrate surface, but the height control requirement becomes extremely stringent at the nanometer scale
Solution Approach 1:
The patent changes the radiation wavelength parameter from visible/UV range to x-ray range (less than 20 nanometers). This enables the use of x-ray diffraction for height measurement, providing nanometer-scale precision that relaxes the stringent height control requirements while maintaining sensor sensitivity through the diffraction-based measurement approach
3Measurement precision
If traditional optical measurement techniques are used, then the system is easy to operate, but the measurement precision deteriorates when material and geometry change across the substrate
Solution Approach 1:
The patent changes the measurement parameter from optical wavelength to x-ray wavelength, enabling height measurement through x-ray diffraction patterns. This approach provides material-insensitive measurement with nanometer precision, achieving high measurement precision while maintaining operational simplicity through automated diffraction pattern analysis
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 robust and accurate height measurements with nanometric precision, minimizing the impact of material and geometric changes, and allowing for precise control of the near field sensor's height, thereby enhancing sensitivity and reliability.
Implementation Method 1
creating a diffraction pattern by illuminating, with a beam of coherent radiation having a wavelength that does not exceed twenty nanometers, a slit that is formed between the substrate and an opaque element
Data Source
AI summary
A method for determining a distance between a near field sensor and a substrate, the method may include creating a diffraction pattern by illuminating, with a beam of coherent radiation having a wavelength that does not exceed twenty nanometers, a slit that is formed between the substrate and an opaque element; detecting, by a detector, multiple portions of the diffraction pattern and generating detection signals indicative of the multiple portions of the diffraction pattern; processing the detection signals to determine a height of the slit; and determining the distance between the near field sensor and the substrate based upon (a) the height of the slit, and (b) a relationship between the height of the slit and a location of the near field sensor.