Diffraction-Order Overlay Metrology for Precise Layer Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lithographic systems face challenges in accurately aligning different layers on a substrate, leading to misalignment errors that reduce the quality and yield of fabricated devices, increasing fabrication time and cost.
Innovation Solution
A system and method utilizing a radiation source, diffractive element, optical element, detector, and processor to generate and analyze first and second scattered beams with different non-zero diffraction orders to determine a property of the target structure, enhancing the accuracy of overlay measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional alignment methods are used, then the lithographic system can operate with standard equipment, but misalignment errors occur that reduce manufacturing precision
Solution Approach 1:
The patent segments the measurement process by separating the detection of different diffraction orders (e.g., +1 and -1 orders) and analyzing their intensity differences. This segmentation allows for more precise overlay measurements by comparing specific diffraction components rather than using conventional whole-pattern alignment methods.
Solution Approach 2:
The patent changes the measurement parameter from conventional position-based alignment to intensity-based diffraction order analysis. By measuring the intensity difference between opposite diffraction orders and using this to determine overlay error, the system achieves higher measurement precision without requiring more complex hardware.
2Measurement precision
If multiple diffraction orders are analyzed with intensity attenuation, then overlay measurement accuracy improves, but the optical system complexity increases
Solution Approach 1:
The patent introduces an optical element (such as a phase shift grating or beam splitter) as an intermediary to create controlled intensity differences between diffraction orders. This intermediary component enables precise measurement of overlay error through intensity comparison without requiring complex detection systems or multiple measurement steps.
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
Improves the accuracy of overlay measurements, reducing misalignment errors and enhancing the quality and yield of fabricated devices by providing precise alignment of layers.
Implementation Method 1
The diffractive element diffracts the radiation to generate a first beam and a second beam. The first beam includes a first non-zero diffraction order and the second beam includes a second non-zero diffraction order
Implementation Method 2
The optical system receives a first scattered beam and a second scattered beam of radiation from the target structure
Data Source
AI summary
The system includes a radiation source, a diffractive element, an optical system, a detector, and a processor. The radiation source generates radiation. The diffractive element diffracts the radiation to generate a first beam and a second beam. The first beam includes a first non-zero diffraction order and the second beam includes a second non-zero diffraction order that is different from the first non-zero diffraction order. The optical system receives a first scattered beam and a second scattered radiation beam from a target structure and directs the first scattered beam and the second scattered beam towards a detector. The detector generates a detection signal. The processor analyzes the detection signal to determine a target structure property based on at least the detection signal. The first beam is attenuated with respect to the second beam or the first scattered beam is purposely attenuated with respect to the second scattered beam.