Electron Microscope Assembly for Lithography Wafer Plane Imaging
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Solution Overview
Problem
The existing knife edge technique for measuring electron beam parameters in lithographic processes faces challenges in achieving nanometer-scale sharpness, edge roughness, and accurate measurement of rotation and magnification, limiting the precision of lithographic processes.
Innovation Solution
An electron microscope system is integrated with an electron beam lithography tool, featuring a translation unit and magnifying lenses to position the microscope proximate to the lithography optics, allowing for the magnification and measurement of a virtual sample plane image, thereby enhancing image resolution and optical condition optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the knife edge technique is used to measure electron beam parameters, then the measurement process is simple, but the measurement precision is insufficient for nanometer-scale parameters
Solution Approach 1:
The patent merges the electron microscope with the lithography tool to form an integrated measurement system. The electron microscope is positioned within the lithography tool's vacuum chamber and optical path, allowing simultaneous viewing of the wafer plane image and measurement of beam parameters without requiring separate measurement equipment.
Solution Approach 2:
The patent introduces a specialized detector positioned at the wafer plane to capture the electron beam image. This detector acts as an intermediary that converts the electron beam information into measurable signals, enabling precise measurement of focus, astigmatism, magnification, rotation, distortion and uniformity parameters.
2Measurement precision
If the knife edge technique is used to measure rotation and magnification, then the measurement process is straightforward, but the accuracy is limited due to single-axis measurement constraint
Solution Approach 1:
The patent transitions from single-axis knife edge measurement to two-dimensional wafer plane imaging. By capturing the complete electron beam image at the wafer plane, the system can simultaneously measure rotation, magnification, distortion and other parameters across multiple axes, dramatically improving measurement accuracy and comprehensiveness.
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 system enables precise measurement and optimization of optical conditions such as focus, astigmatism, magnification, and image uniformity, improving the accuracy and resolution of lithographic processes, particularly in reflective electron beam lithography.
Implementation Method 1
one or more magnifying lenses oriented about an optical axis of the electron microscope configured to magnify a virtual sample plane image generated by the electron beam lithography tool
Implementation Method 2
a virtual sample plane image generated by the electron beam lithography tool
Data Source
AI summary
An electron microscope assembly suitable for enhancing an image of a lithography tool includes an electron microscope configured for positioning below a lithography stage of an e-beam lithography tool, the lithography stage of the e-beam lithography tool including an aperture for providing the microscope line-of-sight to the lithography optics of the lithography tool, a translation unit configured to selectively translate the microscope along the optical axis of the lithography optics of the lithography tool responsive to a translation control system, the translation unit further configured to position the microscope in an operational state such that the optics of the microscope are positioned proximate to the lithography optics, a docking unit configured to reversibly mechanically couple the microscope with the lithography tool, the microscope configured to magnify a virtual sample plane image generated by the lithography tool.