Multi-Charged Particle Beam Writing Apparatus Dose Control
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Solution Overview
Problem
Multi-beam writing techniques face challenges in reducing writing time while minimizing the influence of pattern density, as higher pattern densities require longer writing times and lower densities result in increased exposure doses, leading to longer overall writing times.
Innovation Solution
A multi-charged particle beam writing apparatus and method that calculates and applies distinct doses for beams corresponding to pattern and no-pattern forming regions, using a combination of aperture members, blankers, and deflection control units to optimize beam exposure and reduce writing time by adjusting doses based on pattern density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple beams are emitted at a time to increase throughput, then writing speed is improved, but the influence of pattern density becomes significant causing writing time to increase for high density patterns
Solution Approach 1:
The patent segments the writing area into pattern forming regions and non-pattern forming regions, applying different dose strategies to each segment. This allows the system to maintain high writing speed for pattern regions while reducing unnecessary exposure in non-pattern regions, thereby reducing overall writing time for high density patterns.
Solution Approach 2:
The patent implements local quality by calculating and applying different doses to different regions: a first dose for pattern forming regions and a second dose for non-pattern forming regions. This localized dose adjustment optimizes writing efficiency by preventing over-exposure in non-pattern areas while ensuring proper exposure in pattern areas.
2Loss of time
If beam current density is increased to compensate for increased number of shots in complicated patterns, then writing time is reduced, but resist heating influence becomes large
Solution Approach 1:
The patent applies partial action by emitting beams only to necessary regions (pattern forming areas) and controlling the dose to be sufficient but not excessive. By avoiding unnecessary exposure in non-pattern regions and using optimized dose levels in pattern regions, the total energy deposited is reduced, thereby mitigating resist heating while maintaining writing speed.
3Loss of time
If higher layout pattern density is used in multi-beam writing, then writing time becomes shorter, but lower layout pattern density requires larger dose leading to longer writing time
Solution Approach 1:
The patent changes the dose parameter based on region type and pattern density. By calculating and applying different dose levels (first dose for pattern regions, second dose for non-pattern regions), the system optimizes the balance between writing speed and exposure requirements. This parameter adjustment allows efficient writing across different pattern densities without requiring excessively large doses.
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 effectively reduces writing time by approximately 15-30% across various pattern densities, mitigating the impact of pattern density on writing time and improving exposure efficiency.
Implementation Method 1
an emission unit configured to emit a charged particle beam; an aperture member, in which a plurality of openings are formed, configured to form multiple beams by letting a region including a whole of the plurality of openings be irradiated with the charged particle beam
Implementation Method 2
a plurality of blankers configured to respectively perform blanking deflection of a corresponding beam in the multiple beams having passed through the plurality of openings of the aperture member; a blanking aperture member configured to block each beam having been deflected to be in a beam-off state by the plurality of blankers
Data Source
AI summary
A multi charged particle beam writing apparatus includes a dose calculation unit to calculate a first dose resolving the resist of the target object, for a first beam of the multiple beams, corresponding to a pattern forming region, in which a pattern is arranged; and to calculate a second dose not resolving the resist, for a second beam of the multiple beams, corresponding to a no-pattern forming region, which surrounds the whole perimeter of the pattern and in which no pattern is arranged, and a deflection control unit to control a plural blankers so that a dose of the first beam is to be the first dose calculated and a dose of the second beam is to be the second dose calculated.