Silicon Wafer 2D Displacement Measurement With Self-Traceable Diffraction
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Solution Overview
Problem
High-precision 2D displacement measurement devices face challenges in achieving sub-nanometric resolution and direct traceability to the meter definition due to complex structures and processing quality issues in existing 2D grating displacement systems.
Innovation Solution
A self-traceable 2D displacement measurement device utilizing a first and second radiation source, silicon wafers with perpendicular lattice planes, and an XY 2D displacement platform, enabling simultaneous 2D displacement measurement with sub-nanometric resolution by Laue diffraction and interference fringe generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a 2D grating displacement measurement system is used, then 2D displacement measurement can be achieved, but the structure becomes complex and processing quality requirements are high
Solution Approach 1:
The patent replaces the mechanical grating structure with a silicon wafer-based diffraction system. Instead of using complex mechanical gratings that require high processing quality, the invention uses the periodic lattice structure of silicon wafers as the diffraction element. This substitution of mechanical components with a crystalline material-based system simplifies the overall structure while maintaining measurement precision through the inherent periodicity of the silicon lattice.
Solution Approach 2:
The patent changes the fundamental parameter of the diffraction element from mechanical grating spacing to silicon lattice plane spacing. By utilizing the well-known and stable lattice parameters of silicon (such as the 0.225 nm spacing for the (220) plane), the system achieves traceability to the meter definition without requiring complex mechanical structures. This parameter change from mechanical dimensions to crystalline lattice dimensions simplifies the system while improving traceability.
2Measurement precision
If a 2D grating displacement measurement system is used, then displacement measurement can be performed, but the measurement result cannot be directly traced to the definition of the meter
Solution Approach 1:
The patent replaces mechanical grating systems with a silicon wafer-based diffraction system that utilizes the crystalline lattice structure. The silicon wafer's periodic lattice planes provide a natural reference that can be directly traced to the meter definition through the known lattice spacing parameters, eliminating the need for complex mechanical calibration chains and achieving direct traceability.
Solution Approach 2:
The silicon wafer system is self-referencing through its inherent crystalline structure. The lattice planes of silicon provide a stable, known reference that does not require external calibration or complex mechanical references. The system uses the silicon lattice itself as the measurement reference, making the measurement self-traceable to the meter definition through the fundamental physical constants of silicon.
3Measurement precision
If existing 2D grating systems are used, then measurement can be achieved, but sub-nanometric resolution is difficult to achieve
Solution Approach 1:
The patent changes the reference parameter from mechanical grating spacing to silicon lattice plane spacing. The silicon lattice provides a natural sub-nanometric reference with known spacing (e.g., 0.225 nm for the (220) plane), enabling sub-nanometric resolution without requiring complex mechanical processing. The crystalline structure inherently provides the necessary precision that mechanical gratings cannot achieve.
Solution Approach 2:
By substituting mechanical gratings with a crystalline silicon wafer system, the patent eliminates the processing quality limitations inherent in mechanical systems. The silicon lattice structure provides a stable, reproducible, and traceable reference that naturally achieves sub-nanometric precision without requiring high-precision mechanical manufacturing and assembly.
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 device achieves sub-nanometric measurement resolution and direct traceability to the meter definition, with a compact spatial structure and wide measurement range, utilizing the spacing of lattice planes in silicon wafers.
Implementation Method 1
a ray emitted from the first radiation source is incident on the first lattice plane of the first silicon wafer at a Bragg angle and undergoes Laue diffraction
Implementation Method 2
the second diffracted light is converged at the third silicon wafer to generate an interference fringe
Implementation Method 3
an intensity of an interference signal received by the first radiation detector changes sinusoidally
Data Source
AI summary
Self-traceable two-dimensional (2D) displacement measurement devices are provided. In some examples, a self-traceable 2D displacement measurement device includes: a first radiation source, a second radiation source, a wafer fixation plate, a first silicon wafer, a second silicon wafer, a third silicon wafer, a first radiation detector, a second radiation detector, and an XY 2D displacement platform. The self-traceable 2D displacement measurement device includes a displacement measurement module in an X-direction and a displacement measurement module in a Y-direction. The first silicon wafer and the second silicon wafer are fixed on the wafer fixation plate in parallel; the third silicon wafer is parallel to the second silicon wafer; a distance from the third silicon wafer to the second silicon wafer is the same as that from the first silicon wafer to the second silicon wafer; the third silicon wafer is fixed on a sidewall of the XY 2D displacement platform.