Wafer Depth Data from Phase Information in Scatterometry
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Solution Overview
Problem
Scatterometry overlay metrology tools face challenges in accurately determining wafer focus and deriving depth data, which affects the precision of overlay measurements and material property analysis.
Innovation Solution
The method involves scanning a wafer region using a metrology tool to perform focus measurements, extract phase information, and derive depth data, enabling profilometry and surface data analysis, which can be used to locate metrology targets, estimate process variation, and improve overlay measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If focus measurements are performed using conventional methods, then overlay measurements can be obtained, but measurement precision of wafer topography and depth data is insufficient
Solution Approach 1:
The patent introduces phase information as an intermediary parameter that mediates between focus measurements and depth data. By extracting phase information from focus measurements and using it to derive depth data, the system achieves higher measurement precision without losing critical topographical information
Solution Approach 2:
The patent transforms focus measurement data into depth data by changing the parameter representation from conventional focus metrics to phase information. This parameter transformation enables more precise characterization of wafer topography and depth variations
2Measurement precision
If additional imaging methods are used to improve topography measurement accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent makes the existing focus measurement system multi-functional by enabling it to perform both overlay measurements and topography/depth measurements. The same optical path and detectors used for overlay measurement are also used to extract phase information for depth data, eliminating the need for separate imaging systems
Solution Approach 2:
The patent merges the overlay measurement function with the topography measurement function into a single integrated system. By combining these functions, the system achieves high measurement precision for both parameters without increasing device complexity
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 simplifies and accelerates wafer topography measurements, enhancing the accuracy of scatterometry overlay metrology and wafer positioning, while providing detailed material property information.
Implementation Method 1
performing focus measurements by the metrology tool during the scanning and extracting therefrom phase information
Implementation Method 2
extracting therefrom phase information
Implementation Method 3
deriving depth data of the scanned wafer region from the extracted phase information
Implementation Method 4
provide profilometry and surface data
Data Source
AI summary
Methods and scatterometry overlay metrology tools are provided, which scan a wafer region, perform focus measurements during the scanning to extract therefrom phase information, and derive depth data of the scanned wafer region from the extracted phase information. The depth information, relating to a dimension perpendicular to the wafer, may be derived along lines or surfaces, providing profilometry and surface data, respectively. The depth data may be used to locate metrology targets, as well as to provide material properties concerning wafer layers, to estimate process variation and to improve the overlay measurements.