Multiple-Objective Metrology for Lithographic Alignment
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Solution Overview
Problem
Existing lithographic systems face challenges in accurately positioning substrates relative to prior patterns with high precision, particularly in aligning alignment marks across different layers, which affects overlay accuracy.
Innovation Solution
A system with multiple objectives is introduced, utilizing an illumination system to split a beam into sub-beams directed to different spots on a substrate, with detectors analyzing diffracted beams to determine properties of target structures, enabling precise alignment and measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single objective is used for inspection, then the device complexity is low, but the measurement precision and alignment accuracy are insufficient
Solution Approach 1:
The inspection system is segmented into multiple independent optical objectives, each targeting a specific region or feature type on the substrate. This allows simultaneous multi-point measurement, improving alignment accuracy while keeping each individual objective relatively simple in design
2Productivity
If multiple objectives are used for simultaneous inspection, then the productivity and measurement speed improve, but the device complexity increases
Solution Approach 1:
Multiple optical objectives are designed with universal functionality to perform the same inspection tasks simultaneously at different locations. This enables parallel processing of alignment marks and target structures, significantly improving measurement speed and productivity while maintaining consistent measurement quality across all objectives
3Measurement precision
If multiple spots on substrate are illuminated simultaneously, then the overlay measurement accuracy improves, but the use of energy increases
Solution Approach 1:
The illumination beam is segmented into multiple sub-beams, with each sub-beam directed to a specific spot or region on the substrate through corresponding optical objectives. This segmented approach enables simultaneous multi-point overlay measurement, improving measurement accuracy while distributing energy consumption across multiple focused illumination points rather than requiring high-power single-point 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
Enhances the accuracy of substrate alignment and overlay measurement, improving the precision of lithographic processes by utilizing multiple objectives for simultaneous inspection and alignment.
Implementation Method 1
The optical system is configured to split the illumination beam into a first sub-beam and a second sub-beam
Implementation Method 2
The detector is configured to receive diffracted beams from the first spot and second spot
Data Source
AI summary
A metrology or inspection system, a lithographic apparatus, and a method are provided. The system includes an illumination system, an optical system, a first optical device, a second optical device, a detector, and a processor. The optical system is configured to split an illumination beam into a first sub-beam and a second sub-beam. The first optical device is configured to receive the first sub beam and direct the first sub-beam towards a first spot on a substrate. The substrate includes one or more target structures. The second optical device is configured to receive the second sub-beam and direct the second sub-beam towards a second spot on the substrate. The first spot is a different location than the second spot. The detector is configured to receive diffracted beams and to generate a detection signal. The processor is configured to determine a property of the one or more target structures.