Charged Particle Beam Device Residual Magnetic Field Reduction
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Solution Overview
Problem
The existing charged particle beam apparatuses face inefficiencies in reducing the effect of residual magnetic fields, which affect the processing and observation accuracy of FIB, requiring faster demagnetization methods to enhance operational efficiency.
Innovation Solution
The apparatus employs a first mode using direct current and a second mode using alternating current in specific coils to efficiently reduce the residual magnetic field, allowing for selective operation modes based on application requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a damped alternating magnetic field is used to demagnetize the residual magnetic field, then the residual magnetic field is reduced to an acceptable level, but it takes several seconds to complete the demagnetization process
Solution Approach 1:
The patent applies periodic action by using alternating current (AC) to generate an alternating magnetic field for demagnetization. The AC current reverses direction periodically, creating a damped alternating magnetic field that progressively reduces the residual magnetic field in the pole piece. This periodic action is more effective than direct current (DC) alone, as it can penetrate and demagnetize the ferromagnetic material through hysteresis heating and magnetic domain realignment, achieving complete demagnetization within several seconds.
Solution Approach 2:
The patent implements dynamics by switching between different operational modes: a first mode using direct current for normal operation, and a second mode using alternating current for rapid demagnetization. The system dynamically adjusts the current type based on whether SEM observation is being performed. When the SEM is not in use, the system automatically activates the AC demagnetization mode to quickly reduce residual magnetic field effects on the FIB ion beam, thereby minimizing time loss while maintaining processing accuracy.
2Manufacturing precision
If the SEM objective lens is turned off to eliminate magnetic field interference, then FIB processing accuracy is improved, but the residual magnetic field in the pole piece still leaks into the specimen chamber
Solution Approach 1:
The patent extracts the harmful residual magnetic field from the pole piece by applying alternating current to generate a demagnetizing field. This AC field progressively reduces the magnetic flux density in the pole piece to near-zero levels, effectively removing the source of magnetic field leakage into the specimen chamber. By targeting and eliminating the residual field at its source rather than merely shielding its effects, the system achieves complete removal of the harmful factor.
Solution Approach 2:
The patent introduces an intermediary mechanism - the alternating current demagnetization system - that mediates between the SEM objective lens and the FIB processing environment. When the SEM is not in use, the AC demagnetization circuit acts as an intermediary to actively neutralize residual magnetic fields in the pole piece, preventing them from leaking into the specimen chamber and affecting FIB ion beam accuracy. This intermediary action ensures high FIB processing precision without requiring permanent structural modifications.
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 effectively suppresses the residual magnetic field, improving the accuracy and efficiency of FIB processing and observation by allowing for quick adjustment and high precision in FIB operations.
Implementation Method 1
a first mode for passing a direct current to a second coil after turning off a first coil, and a second mode for passing an alternating current to the second coil after turning off the first coil
Data Source
AI summary
The present invention provides a charged particle beam apparatus capable of efficiently reducing the effect of a residual magnetic field when SEM observation is performed. The charged particle beam apparatus according to the present invention includes a first mode for passing a direct current to a second coil after turning off a first coil, and a second mode for passing an alternating current to the second coil after turning off the first coil.