Integrated OCD Metrology with Normal and Oblique Optical Paths
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Solution Overview
Problem
Current measurement systems in the semiconductor industry, both off-line and in-situ, fail to provide accurate real-time measurements for complex patterned structures, especially when shrinking dimensions and dynamic processes require close to real-time feedback loops, which is not achievable with standalone or end-point detection devices.
Innovation Solution
A novel integrated optical metrology system designed for optical critical dimension (OCD) measurements, capable of switching between normal and oblique measurement schemes, with a compact footprint, allowing for azimuth and polarization variations, and featuring a support assembly for rotation and movement, an optical system with multiple lens units, and an optical window arrangement for efficient light propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an integrated measurement system is designed with both normal and oblique measurement schemes, then measurement precision and information completeness are improved, but device complexity and footprint increase
Solution Approach 1:
The optical head is designed to perform multiple measurement functions (normal incidence and oblique incidence measurements) using a unified structure. The system can switch between different measurement schemes without requiring separate dedicated devices, thereby improving measurement precision while controlling complexity through multi-functionality.
Solution Approach 2:
The system employs dynamic switching between normal and oblique measurement schemes based on measurement requirements. The optical path and measurement mode can be adjusted dynamically, allowing the system to adapt to different structural measurement needs while maintaining a compact footprint through conditional operation rather than permanent dual-path complexity.
2Measurement precision
If an integrated measurement system is designed with both normal and oblique measurement schemes, then measurement precision and information completeness are improved, but footprint increases
Solution Approach 1:
A single optical head design serves dual purposes by supporting both normal and oblique measurement schemes. This multi-functional approach eliminates the need for separate measurement devices, improving precision while minimizing footprint through shared optical components and unified structural design.
Solution Approach 2:
The patent combines normal and oblique measurement capabilities into a single integrated optical system. By merging the optical paths, detection mechanisms, and control systems into one unified structure, the system achieves enhanced measurement precision without proportionally increasing the physical footprint.
3Device complexity
If offline measurement systems are used, then device complexity is reduced, but productivity and real-time feedback capability deteriorate
Solution Approach 1:
The integrated measurement system is designed to provide real-time feedback by being physically installed inside the processing equipment. This enables closed-loop control where measurement results immediately inform process adjustments, dramatically improving productivity and response time while maintaining manageable complexity through direct integration rather than separate offline systems.
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 comprehensive and accurate OCD measurements on complex structures by providing additional information through different measurement schemes, facilitating closed-loop control and feed-forward processes, while maintaining a small footprint for integration with processing equipment.
Implementation Method 1
an optical system defining illumination and collection light channels of normal and oblique optical schemes
Implementation Method 2
propagation of light returned from an illuminated region to the optical head
Data Source
AI summary
A measurement system is presented configured for integration with a processing equipment for applying optical measurements to a structure. The measurement system comprises: a support assembly for holding a structure under measurements in a measurement plane, configured and operable for rotation in a plane parallel to the measurement plane and for movement along a first lateral axis in said measurement plane; an optical system defining illumination and collection light channels of normal and oblique optical schemes and comprising an optical head comprising at least three lens units located in the illumination and collection channels; a holder assembly comprising: a support unit for carrying the optical head, and a guiding unit for guiding a sliding movement of the support unit along a path extending along a second lateral axis perpendicular to said first lateral axis; and an optical window arrangement comprising at least three optical windows made in a faceplate located between the optical head at a certain distance from the measurement plane. The optical windows are aligned with the illumination and collection channels for, respectively, propagation of illuminating light from the optical head and propagation of light returned from an illuminated region to the optical head, in accordance with the normal and oblique optical schemes.