Wafer Orientation Measurement for X-ray Scatterometry
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Solution Overview
Problem
Current X-ray metrology systems face challenges in accurately measuring the orientation of semiconductor wafers due to wafer tilt and curvature, leading to measurement errors and reduced tool throughput, especially when dealing with complex three-dimensional structures and opaque materials.
Innovation Solution
The implementation of a wafer orientation measurement system that allows for precise measurement of wafer orientation at a single point without intervening stage moves, enabling simultaneous X-ray scatterometry measurements and using advanced signal filtering techniques to improve tracking of the wafer's actual orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional multi-point wafer orientation measurement methods are used, then comprehensive wafer tilt data can be obtained, but measurement time increases and tool throughput decreases
Solution Approach 1:
The patent extracts and measures only the critical local wafer orientation parameters (tilt and curvature) at the specific measurement location rather than performing comprehensive multi-point measurements. This selective extraction of necessary information reduces measurement time while maintaining accuracy for the relevant parameters.
Solution Approach 2:
The system performs preliminary measurement of wafer orientation parameters before the main X-ray scatterometry measurement. This preliminary action allows for real-time correction and compensation, ensuring accurate measurements without requiring time-consuming post-processing or repeated measurements.
2Productivity
If wafer tilt is not compensated, then measurement process is simpler and faster, but measurement accuracy deteriorates due to orientation errors
Solution Approach 1:
The patent implements a feedback mechanism where wafer orientation parameters measured by the optical system are used to correct and compensate the main X-ray scatterometry measurements in real-time. This closed-loop approach maintains high measurement accuracy without requiring mechanical repositioning or slowing down the measurement process.
Solution Approach 2:
Instead of using mechanical systems to physically adjust or reposition the wafer to compensate for tilt, the patent substitutes an optical measurement and computational correction system. This replacement maintains measurement speed while achieving accuracy through software-based compensation rather than mechanical adjustment.
3Device complexity
If optical radiation is used for metrology, then the system is simpler and faster, but penetration depth is insufficient for complex 3D structures
Solution Approach 1:
The patent merges two different measurement systems: an optical system for measuring wafer orientation parameters and an X-ray system for measuring structures beneath the surface. The optical system provides surface orientation data that enables accurate positioning and interpretation of X-ray measurements, combining the advantages of both methods without requiring either system to work alone.
Solution Approach 2:
The optical measurement system acts as an intermediary that provides critical orientation information about the wafer surface. This intermediary data enables the X-ray system to accurately interpret measurements by compensating for surface tilt and curvature, allowing the X-ray system to effectively penetrate and measure deep 3D structures without the optical system needing to provide direct deep penetration capability.
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 enhances measurement accuracy and reduces errors by providing rapid and accurate wafer orientation data, improving the precision of X-ray scatterometry measurements and increasing tool throughput.
Implementation Method 1
a wafer orientation measurement system that generates a measurement of wafer orientation at a measurement location based on a single measurement without intervening stage moves
Implementation Method 2
x-ray scatterometry measurements
Implementation Method 3
X-ray based metrology
Data Source
AI summary
Methods and systems for measuring the orientation of a wafer at or near an X-ray scatterometry measurement location are described herein. In one aspect, an X-ray scatterometry based metrology system includes a wafer orientation measurement system that measures wafer orientation based on a single measurement without intervening stage moves. In some embodiments, an orientation measurement spot is coincident with an X-ray measurement spot. In some embodiments, an X-ray scatterometry measurement and a wafer orientation measurement are performed simultaneously. In another aspect, signals detected by a wafer orientation measurement system are filtered temporally, spatially, or both, to improve tracking. In another aspect, a wafer orientation measurement system is calibrated to identify the orientation of the wafer with respect to an incident X-ray beam. In another aspect, a wafer under measurement is positioned based on the measured orientation in a closed loop or open loop manner.