Moving-Stage Electron Beam Alignment for Non-Contact Electrical Measurement
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Solution Overview
Problem
The movement of a semiconductor wafer or device under test on a movable stage introduces uncertainty in the testing process, leading to throughput delays and errors due to difficulty in precisely determining the position of the wafer before, during, and after movement, especially during non-contact electrical measurements using particle or electron beams.
Innovation Solution
A system and method for non-contact electrical measurement (NCEM) on a moving NCEM-enabled cell vehicle, where the movement of the stage is compensated by adjusting the deflection angle of the electron beam responsive to the stage's continuous or varying movement, using position assessment hardware to determine absolute and relative positions, allowing continuous testing without stopping the stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the stage moves the wafer continuously to facilitate testing of different regions, then productivity is improved, but measurement precision deteriorates due to uncertainty in determining the position of the wafer before, during, and after movement
Solution Approach 1:
The system uses position assessment hardware to continuously monitor the stage position and feeds this information back to the control system. The control system then adjusts the electron beam deflection angle based on this feedback to maintain accurate targeting of wafer features despite continuous stage movement, resolving the contradiction between continuous motion for productivity and position precision for measurement accuracy.
Solution Approach 2:
The patent replaces mechanical positioning dependency with an electronic correction system. Instead of relying solely on mechanical stage positioning accuracy, the system uses electronic deflection angle adjustment of the electron beam to compensate for stage movement, substituting mechanical precision requirements with electronic control capabilities.
2Measurement precision
If the stage stops to position the wafer precisely under the electron beam, then measurement precision is improved, but productivity deteriorates due to throughput delays
Solution Approach 1:
The system transitions from a static positioning approach (stopping the stage) to a dynamic compensation approach. The electron beam deflection angle is continuously adjusted in real-time to track and compensate for stage movement, allowing precise measurements to be taken during continuous motion rather than requiring the stage to stop, thus maintaining both precision and productivity.
Solution Approach 2:
The patent enables continuous testing by maintaining the electron beam's alignment with wafer features throughout continuous stage movement. The useful action of testing different regions continues uninterrupted as the stage moves, with the deflection angle adjustment ensuring the beam remains properly positioned on target features without requiring stopping.
3Measurement precision
If the electron beam deflection angle is adjusted continuously to compensate for stage movement, then measurement precision is maintained during motion, but device complexity increases due to additional position assessment hardware and control mechanisms
Solution Approach 1:
The position assessment hardware serves multiple functions: it monitors stage position, provides feedback for deflection angle adjustment, and enables continuous motion compensation. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in overall system complexity while achieving continuous precision measurement.
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 increases throughput by enabling continuous testing of semiconductor devices like chips, wafers, and logic portions without impacting operational integrity, reducing yield loss and improving precision in determining the position of the wafer during electron beam inspection.
Implementation Method 1
A response of the target to the particle beam may be detected and analyzed to determine, for example, whether the target's response to the particle beam is correct and/or indicates whether the target is operational and/or defective
Data Source
AI summary
Systems, devices, and methods for performing a non-contact electrical measurement (NCEM) on a NCEM-enabled cell included in a NCEM-enabled cell vehicle may be configured to perform NCEMs while the NCEM-enabled cell vehicle is moving. The movement may be due to vibrations in the system and/or movement of a movable stage on which the NCEM-enabled cell vehicle is positioned. Position information for an electron beam column producing the electron beam performing the NCEMs and/or for the moving stage may be used to align the electron beam with targets on the NCEM-enabled cell vehicle while it is moving.