Multi-Column Electron Beam Inspection for High-Throughput CD Metrology
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Solution Overview
Problem
The increasing complexity and miniaturization of semiconductor devices require more stringent accuracy in overlay, critical dimension, and registration errors during the patterning process, which existing metrology techniques struggle to meet, especially with the limitations of single electron beam column inspection systems in terms of throughput and resolution.
Innovation Solution
A multi-column electron beam inspection system with a plurality of electron beam columns, each configured to provide an electron beam and detect scattered or secondary electrons, and an actuator system for relative movement between columns to inspect specific areas of a substrate, allowing parallel inspection and increased throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single electron beam column inspection system is used, then the device complexity is low, but the productivity and measurement precision are insufficient to meet the stringent accuracy requirements for overlay, critical dimension, and registration errors
Solution Approach 1:
The inspection system is divided into multiple electron beam columns, with each column independently inspecting a specific die or field on the substrate. This segmentation allows parallel inspection operations across multiple columns, simultaneously improving measurement precision for critical dimensions and increasing productivity through concurrent inspections of multiple areas
Solution Approach 2:
The system transitions from a single-beam inspection approach to a multi-column array configuration, adding spatial dimensionality to the inspection process. Multiple beams operate simultaneously in parallel, transforming the inspection from a sequential single-point operation to a multi-point concurrent operation across the substrate surface
2Measurement precision
If the entire area of each die or field is inspected by electron beam columns, then the measurement precision is maximized, but the productivity decreases due to the time required to inspect large areas
Solution Approach 1:
Each electron beam column is assigned to inspect a specific die or field area, segmenting the total inspection task into parallel sub-tasks. This allows the system to maintain high measurement precision within each segmented area while reducing total inspection time through simultaneous execution across multiple columns
Solution Approach 2:
The system inspects specific areas of each die or field rather than the entire area, applying partial action principle. By focusing electron beam columns on critical regions or representative samples within each die/field, the system achieves sufficient measurement precision while significantly reducing the time required compared to complete area inspection
3Productivity
If multiple electron beam columns are used to increase throughput, then the productivity improves, but the device complexity increases
Solution Approach 1:
The multi-column system segments the inspection function into independent, identical modular units. Each electron beam column operates as a self-contained module with similar complexity, allowing the system to scale productivity by adding identical segments rather than designing increasingly complex single-unit systems
Solution Approach 2:
Each electron beam column is designed as a universal, multi-functional unit capable of performing the complete inspection function independently. This universality allows multiple columns to be combined in array configurations to increase throughput while maintaining manageable individual column complexity, as each column serves the same purpose and can be independently controlled
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 the ability to detect defects and measure critical dimensions with higher resolution and throughput, significantly improving the accuracy and efficiency of the patterning process by inspecting less than the entire area of each die or field, thereby addressing the limitations of single-beam systems.
Implementation Method 1
A multi-column electron beam inspection system with a plurality of electron beam columns, each configured to provide an electron beam and detect scattered or secondary electrons
Implementation Method 2
detect scattered or secondary electrons from the substrate
Data Source
AI summary
An electron beam inspection apparatus, the apparatus including a plurality of electron beam columns, each electron beam column configured to provide an electron beam and detect scattered or secondary electrons from an object, and an actuator system configured to move one or more of the electron beam columns relative to another one or more of the electron beam columns, the actuator system including a plurality of first movable structures at least partly overlapping a plurality of second movable structures, the first and second movable structures supporting the plurality of electron beam columns.