Simultaneous Dark Field and Phase Contrast Inspection
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Solution Overview
Problem
Current semiconductor wafer inspection tools cannot simultaneously perform dark field and differential interference contrast inspections due to differences in optical components and detection signals, making it time-consuming and inefficient to detect and classify defects.
Innovation Solution
An apparatus and method for simultaneous dark field and differential interference contrast inspection using an optical sub-system with illumination sources, a sample stage, and sensors, where the optical sub-system directs and separates scattering-based and phase-based signals into distinct paths for each type of inspection, allowing for simultaneous data acquisition and fusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate optical layouts are used for dark field and differential interference contrast inspection, then each inspection mode can be optimized independently, but the inspection process becomes time-consuming and cannot be performed simultaneously
Solution Approach 1:
The patent combines dark field and differential interference contrast optical layouts into a single integrated inspection system. The optical sub-system includes components that enable both inspection modes to operate simultaneously through a unified illumination and detection architecture, allowing dual-mode inspection without sequential operation.
Solution Approach 2:
The inspection tool is designed with multi-functional optical components that can perform both dark field and differential interference contrast inspection functions simultaneously. The optical sub-system incorporates elements that support multiple inspection modes through a single optical path configuration, enabling the system to execute diverse inspection tasks without requiring separate dedicated systems.
2Productivity
If a single optical system is used for both dark field and differential interference contrast inspection, then simultaneous inspection is enabled, but the optical component design becomes more complex and incompatible
Solution Approach 1:
The optical system is segmented into distinct functional modules including separate illumination sources, optical paths, and detection channels for dark field and differential interference contrast inspection. This modular segmentation allows each inspection mode to be independently optimized while maintaining simultaneous operation capability, reducing the complexity of integrating both modes into a single monolithic system.
Solution Approach 2:
The patent employs intermediary optical components such as beam splitters, dichroic mirrors, and optical isolators that mediate between the two inspection modes. These intermediary elements enable the separation and routing of optical paths for dark field and differential interference contrast inspection, allowing both modes to coexist in a single system without direct interference, thereby managing optical system complexity.
3Measurement precision
If separate inspection operations are performed for dark field and differential interference contrast, then signal detection can be optimized for each mode, but the overall defect detection and classification value is reduced
Solution Approach 1:
The patent merges the detection channels of dark field and differential interference contrast inspection into a unified data acquisition system. The sensor sub-system simultaneously captures scattering-based signals from dark field inspection and phase-based signals from differential interference contrast inspection, combining both signal types to provide complete defect information for enhanced detection and classification accuracy.
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 enhanced detection and classification of defects by combining scattering-based and phase-based information, improving the efficiency of semiconductor wafer inspection processes.
Implementation Method 1
an objective configured to collect a collected signal from the surface of the sample, wherein the collected signal includes at least one of a scattering-based signal and a phase-based signal from the sample
Implementation Method 2
one or more separation optical elements arranged to spatially separate the collected signal into a dark field signal and a differential interference contrast signal by directing the dark field signal along a dark field path to the first sensor and the differential interference contrast signal along a differential interference contrast path to the second sensor
Data Source
AI summary
An inspection apparatus for simultaneous dark field (DF) and differential interference contrast (DIC) inspection includes an illumination source and a sample stage configured to secure a sample. The inspection apparatus includes a first sensor, a second sensor and an optical sub-system. The optical sub-system includes an objective, one or more optical elements arranged to direct, through the objective, illumination from the one or more illumination sources to a surface of the sample. The objective is configured to collect a signal from the surface of the sample, wherein the collected signal includes a scattering-based signal and/or a phase-based signal from the sample. The inspection apparatus includes one or more separation optical elements arranged to spatially separate the collected signal into a DF signal and a DIC signal by directing the DF signal and the DIC signal along a DF path and DIC path respectively.