Ellipsometer Azimuth Rotation for Small Pattern Precision
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Solution Overview
Problem
Current ellipsometers face challenges in accurately measuring physical properties of small substrate patterns due to limitations in reducing incident light beam size, leading to difficulties in focusing light on reduced measurement regions, especially as semiconductor device patterns shrink.
Innovation Solution
An ellipsometer design that includes a light source, polarization unit, detector, and controller, which rotates the detector by an azimuth angle to maintain effective measurement region alignment and masks inactive regions, using a 2D area image sensor and compensator to analyze polarization changes and adjust polarization states, allowing for precise measurement of substrate patterns without data collection from inactive areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the beam size of incident light is reduced to measure smaller substrate patterns, then measurement precision is improved, but diffraction phenomenon increases and makes further beam size reduction challenging
Solution Approach 1:
The patent divides the measurement process into multiple azimuth angle measurements. Instead of using a single small beam, the system uses a wider beam and segments the measurement by taking multiple readings at different azimuth angles (e.g., 0°, 45°, 90°, 135°), then combines these measurements to achieve precise characterization of the substrate pattern without suffering from diffraction limitations of small beams.
Solution Approach 2:
The patent introduces the azimuth angle dimension to solve the beam size problem. By measuring at multiple azimuth angles rather than relying on a single small beam in one direction, the system effectively adds a rotational dimension to the measurement process, enabling precise measurement of small patterns without the diffraction issues that plague conventional small-beam approaches.
2Measurement precision
If the measurement region area is reduced to match smaller test piece patterns, then measurement precision is improved, but the time to process and analyze data from the measurement region increases
Solution Approach 1:
The patent performs preliminary actions by pre-calculating azimuth angles and measurement parameters before actual measurement. The system determines the optimal azimuth angle sequence and measurement region in advance, which streamlines the data collection process and reduces the time required for real-time data processing and analysis during the actual measurement of small patterns.
Solution Approach 2:
The patent maintains continuous useful action by implementing a seamless measurement sequence where multiple azimuth angle measurements are taken in rapid succession without interrupting the measurement flow. The system continuously collects data across different azimuth angles and processes this information in real-time, eliminating idle time between measurements and maintaining continuous productive operation throughout the characterization process.
3Measurement precision
If multiple azimuth angle measurements are taken to improve measurement accuracy of small patterns, then measurement precision is improved, but measurement time increases
Solution Approach 1:
The patent applies periodic action by measuring at regularly spaced azimuth angles (e.g., 0°, 45°, 90°, 135°). This periodic measurement approach allows the system to capture sufficient information for accurate pattern characterization using a standardized sequence of measurements, which can be efficiently executed and processed, balancing measurement precision with acceptable measurement time.
4Ease of operation
If a wide-area light source is used to irradiate the substrate, then ease of operation is improved, but measurement precision for small regions deteriorates
Solution Approach 1:
The patent applies local quality by analyzing the polarization properties of light at different spatial locations across the substrate surface. Even though a wide-area light source illuminates the entire substrate, the system extracts localized measurement information by examining polarization changes at specific measurement regions and azimuth angles, enabling precise local characterization while maintaining the operational simplicity of wide-area illumination.
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
This approach enables accurate measurement of physical properties on small substrate patterns by maintaining measurement region alignment and reducing data processing time, thereby shortening overall measurement time and improving data transfer efficiency.
Implementation Method 1
a polarization unit configured to polarize the light irradiated from the light source and analyze the polarized light
Implementation Method 2
a detector configured to measure a light quantity of the polarized light passing through the polarization unit
Data Source
AI summary
An ellipsometer for detecting a surface including a light source irradiating a substrate with light, a polarization unit polarizing the light irradiated from the light source and analyzing the polarized light, a detector measuring a light quantity of the polarized light passing through the polarization unit, and a driver rotating the detector by an azimuth angle as the substrate rotates in a direction of the azimuth angle direction may be provided.