Multi-beam Writing Apparatus Drift Correction
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Solution Overview
Problem
Multi-charged particle beam writing apparatuses face challenges in maintaining position accuracy due to beam drift, which affects the throughput and quality of pattern writing on semiconductor devices, especially in multi-beam systems where beam shaping and blanking control are complex and prone to contamination and position deviations.
Innovation Solution
A multi-charged particle beam writing apparatus and method that includes a beam forming member with specific openings for writing and measurement beams, a blanking plate with deflectors, a limiting aperture member, and mark members for precise measurement and correction of beam positions, allowing for real-time drift correction and improved position accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple beams are used for writing to increase throughput, then productivity is improved, but device complexity increases and beam drift occurs more easily
Solution Approach 1:
The patent divides the beam system into writing beams (through first openings) and measurement beams (through second openings). This segmentation allows independent measurement of beam positions without interfering with the writing process, enabling drift correction while maintaining high throughput multi-beam writing capability.
Solution Approach 2:
The patent introduces mark members as intermediary reference objects that measurement beams interact with to detect beam position drift. These mark members serve as mediators between the measurement beams and the control system, enabling precise drift detection and correction without adding complexity to the beam shaping structure.
2Productivity
If beam current density is increased to shorten writing time, then productivity is improved, but resist heating increases and writing quality deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where measurement beams continuously monitor beam positions via mark members, and the control unit adjusts blanking control based on detected drift. This feedback loop enables maintaining optimal writing conditions at higher current densities by compensating for drift that would otherwise cause dose variations and heating-related quality issues.
3Productivity
If shaping aperture size is increased to accommodate multiple beams, then productivity is improved, but adherent contamination increases and position accuracy deteriorates
Solution Approach 1:
The patent extracts the measurement function from the writing beam path by using separate second openings for measurement beams. This allows the shaping aperture to be optimized for writing (first openings) while independently measuring drift through second openings, maintaining position accuracy without sacrificing multi-beam productivity.
Solution Approach 2:
The patent creates a copy of the beam path for measurement purposes. Measurement beams follow a similar path through the shaping aperture and blanking plate as writing beams, allowing drift detection at the same locations without requiring additional complex positioning structures.
4Manufacturing precision
If beam drift correction is implemented to maintain position accuracy, then manufacturing precision is improved, but device complexity and measurement difficulty increase
Solution Approach 1:
The patent uses mark members with distinct visual characteristics (described as having different colors or visual properties) that facilitate easy detection by measurement beams. These marked reference objects provide clear, unambiguous signals for beam position detection, simplifying the measurement process while maintaining high position accuracy.
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
The solution enables accurate drift correction at the shaping section of multiple beams, preventing beam blockages and ensuring consistent dose delivery to the target object, thereby enhancing the position accuracy and throughput of multi-beam writing processes.
Implementation Method 1
an emission unit that emits a charged particle beam; a beam forming member in which a plurality of first openings for writing and a plurality of second openings not for writing are formed around the plurality of first openings
Implementation Method 2
a blanking plate having a plurality of blankers that respectively perform blanking deflection for a corresponding beam in the multiple beams for writing and the multiple beams for measurement
Implementation Method 3
a converging lens that converges the multiple beams for writing and the multiple beams for measurement that have passed through the blanking plate
Data Source
AI summary
A multi charged particle beam writing apparatus includes a beam forming member, where first openings for writing and second openings not for writing around the first openings are formed, to form multiple beams for writing and to form multiple beams for measurement, plural mark members on a blanking aperture member arranged close to the height position where crossover is formed, a measurement unit to measure positions of the multiple beams for measurement by the plural mark members, and a correction unit to correct a voltage for making a “beam on” state applied to one of the plural blankers, in order to correct a position deviation amount of a measured position.