Aperture Array Alignment for Multi-Beam Writing
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Solution Overview
Problem
Conventional multi-beam writing apparatuses face issues with beam loss due to displacement, tilting, or warping of the aperture array, leading to incomplete pattern formation on semiconductor devices.
Innovation Solution
An aperture array alignment method that involves emitting a charged particle beam through a shaping aperture array, performing blanking deflection using a blanking aperture array, and detecting beam current to generate current maps, allowing for precise adjustment of the aperture array's position and orientation to ensure optimal beam alignment and pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple beams are formed by a shaping aperture array in a multi-beam writing apparatus, then throughput is significantly improved, but beam loss occurs due to aperture array displacement, tilting, or warping
Solution Approach 1:
The patent performs preliminary alignment of the blanking aperture array relative to the shaping aperture array before actual beam writing. By pre-adjusting the positional relationship between the two aperture arrays using detection beams and current maps, the system ensures that all multiple beams will correctly pass through the blanking aperture openings during subsequent writing operations, preventing beam loss while maintaining high throughput
Solution Approach 2:
The patent employs a feedback mechanism where beam current is detected by a detector on the stage, current maps are generated based on detection results and aperture array positions, and these current maps are used to adjust the aperture array positions. This closed-loop feedback system continuously optimizes the alignment between shaping and blanking aperture arrays, ensuring reliable beam passage while maintaining high productivity
2Reliability
If the blanking aperture array is precisely aligned to ensure all beams pass through, then beam loss is prevented, but the alignment process becomes complex requiring current maps and iterative adjustments
Solution Approach 1:
The patent implements a self-alignment mechanism where the system uses its own beam current detection capability to automatically generate current maps and determine optimal aperture array positions without requiring external alignment equipment or manual intervention. The detector on the stage measures beam current, the system automatically processes this data into current maps, and uses these maps to self-correct aperture array positioning, thereby reducing operational complexity while ensuring reliable beam passage
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 method ensures that multiple beams pass through the aperture array correctly, maintaining the integrity of the beam array and pattern formation on the substrate, thereby improving the precision and completeness of the semiconductor device patterns.
Implementation Method 1
emitting a charged particle beam, forming multiple beams by allowing the charged particle beam to pass through a plurality of openings in a shaping aperture array plate
Implementation Method 2
The blanking aperture array has electrode pairs configured to deflect individual beams, and each of the electrode pairs has an opening for beam passage between its electrodes. While one electrode of each electrode pair (blanker) is fixed at the ground potential, the other electrode is switched between the ground potential and another potential, and thus electron beams passing through are individually subjected to blanking deflection.
Implementation Method 3
detecting beam current on a stage using a detector disposed on the stage, the stage being capable of holding a substrate thereon
Data Source
AI summary
An aperture array alignment method according to the present embodiment includes switching on and off of each of multiple beams using a blanking aperture array plate, and detecting beam current on a stage using a detector. At least one of the multiple beams is turned on to scan the blanking aperture array plate, and a current map is generated on the basis of a result of detection of the beam current made by the detector and a position of the blanking aperture array plate. An on-beam is switched from one to another to generate the current map for each of the on-beams. The position of the blanking aperture array plate is adjusted on the basis of the current maps for the on-beams.