Charged Particle Beam Writing Apparatus with Magnet Coil Angle Control
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Solution Overview
Problem
In electron beam writing apparatuses, maintaining a consistent beam incident angle to the target object surface is challenging during blanking voltage changes, leading to positional deviations and defocusing issues, as existing systems lack the ability to fine-tune the blanking voltage for precise angle control.
Innovation Solution
The apparatus includes a blanking deflector, electron lens, and magnet coils to adjust the beam trajectory, allowing for precise control of the beam incident angle by varying the voltage applied to the electron lens and magnet coils, ensuring the beam remains perpendicular to the target surface even with blanking voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If binary voltage values are used for blanking operation to secure blanking speed and voltage stability, then blanking response and voltage stability are improved, but beam incident angle control precision deteriorates
Solution Approach 1:
The blanking voltage control is segmented into two independent parts: a binary voltage signal for rapid blanking switching (handled by the blanking deflector) and a fine-adjustment voltage signal for precise incident angle control (handled by the magnet coil). This segmentation allows each component to optimize its function without interfering with the other.
Solution Approach 2:
The magnet coil acts as an intermediary device between the binary blanking voltage system and the beam trajectory. It converts electrical current into magnetic field adjustments that fine-tune the beam incident angle, mediating between the coarse binary voltage control and the precise angular positioning requirement.
2Adaptability or versatility
If blanking voltage is changed during beam-on period, then blanking operation functionality is improved, but beam incident angle stability deteriorates
Solution Approach 1:
The system measures the actual beam incident angle during blanking operation and uses this feedback information to adjust the magnet coil current, compensating for any incident angle changes caused by blanking voltage variations. This closed-loop feedback ensures incident angle stability despite binary voltage switching.
Solution Approach 2:
The system changes the magnetic field parameter (via magnet coil current) in response to blanking voltage changes, dynamically adjusting the beam trajectory to maintain constant incident angle. This parameter compensation approach decouples the incident angle stability from the blanking voltage fluctuations.
3Measurement precision
If beam deflection is performed by fine-tuning blanking voltage, then beam incident angle measurement capability is improved, but voltage control flexibility deteriorates
Solution Approach 1:
The voltage control system is segmented into a blanking voltage channel (for binary on/off control) and a magnet coil current channel (for continuous fine-adjustment). This segmentation provides both measurement capability through continuous control and operational simplicity through binary switching, resolving the contradiction between precision and ease of operation.
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 solution ensures the beam incident angle remains consistent, reducing positional deviations and maintaining focus, thereby enhancing the accuracy and precision of pattern writing on semiconductor devices.
Implementation Method 1
a magnet coil, arranged in a center height position of the blanking deflector, configured to deflect the charged particle beam
Implementation Method 2
an electron lens configured to converge the charged particle beam
Implementation Method 3
a blanking deflector, arranged backward of the electron lens with respect to a direction of an optical axis, configured to deflect the charged particle beam in a case of performing a blanking control of switching between beam-on and beam-off
Data Source
AI summary
A charged particle beam writing apparatus according to one aspect of the present invention includes an emission unit to emit a charged particle beam, an electron lens to converge the charged particle beam, a blanking deflector, arranged backward of the electron lens with respect to a direction of an optical axis, to deflect the charged particle beam in the case of performing a blanking control of switching between beam-on and beam-off, a blanking aperture member, arranged backward of the blanking deflector with respect to the direction of the optical axis, to block the charged particle beam having been deflected to be in a beam-off state, and a magnet coil, arranged in a center height position of the blanking deflector, to deflect the charged particle beam.