Multi-Charged Particle Beam Alignment via Aperture Plate Detector
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The adjustment of the optical axis in multi-charged particle beam writing apparatuses is critical for ensuring that electron beams are perpendicularly incident on the shaping aperture array, as improper alignment leads to partial beam loss and reduced writing accuracy.
Innovation Solution
A multi-charged particle beam writing apparatus with an alignment mechanism that includes alignment coils and a detector-equipped aperture plate, which calculates a feature quantity representing the perpendicularity of the electron beam's incidence and adjusts the optical axis using a coil control unit to ensure uniform brightness distribution in the alignment scan image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the optical axis is not accurately adjusted, then the alignment process is simpler, but the beam array is partially lost and writing accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the detector monitors the beam position on the aperture plate and provides signals to the alignment coil control unit. The system automatically adjusts the alignment coil currents based on detected beam position deviations, creating a closed-loop feedback system that maintains accurate optical axis alignment without requiring complex manual adjustment procedures
Solution Approach 2:
The alignment system performs self-adjustment through the automatic feedback loop. The detector continuously monitors beam position and the control unit automatically adjusts the alignment coils to correct any deviations, enabling the system to self-correct alignment errors without external intervention or complex manual procedures
2Measurement precision
If a detector-equipped aperture plate is added to detect beam position, then optical axis adjustment accuracy improves, but device complexity increases
Solution Approach 1:
The aperture plate serves multiple functions: it defines the beam shape for writing, acts as a reference for alignment, and incorporates a detector for position monitoring. By making the aperture plate multi-functional, the patent avoids adding separate alignment reference structures, thereby limiting the increase in device complexity while achieving precise beam position detection
Solution Approach 2:
The patent merges the alignment detection function with the existing aperture plate structure. The detector is integrated into the aperture plate itself, combining the beam-shaping function and the alignment-monitoring function into a single component, which reduces the number of separate parts and simplifies the overall alignment mechanism
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 accurately adjusts the optical axis, preventing beam array loss and enhancing writing accuracy by ensuring the electron beam is perpendicularly incident on the aperture member, thereby improving the precision of pattern formation on semiconductor substrates.
Implementation Method 1
an alignment coil adjusting an angle of incidence of the charged particle beam on the aperture plate
Implementation Method 2
a detector provided in the aperture plate and detecting charged particles
Data Source
AI summary
In one embodiment, a multi charged particle beam writing apparatus includes an emitter emitting a charged particle beam, a shaping aperture array forming multiple beams by allowing the charged particle beam to pass through a plurality of opening portions, an alignment unit disposed between the emitter and the shaping aperture array, the alignment unit including an aperture plate, a detector provided in the aperture plate and detecting charged particles, and an alignment coil adjusting an angle of incidence of the charged particle beam on the aperture plate, a feature quantity calculating unit calculating, from an alignment scan image based on a detection value of the detector, a feature quantity representing a perpendicularity of the angle of incidence of the charged particle beam on the aperture plate, and a coil control unit controlling an excitation value of the alignment coil based on the feature quantity.