Charged Particle Beam Writing Apparatus Dose Modulation
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Solution Overview
Problem
The increasing integration density of semiconductor devices requires higher precision in circuit pattern formation, leading to longer writing times due to increased resist sensitivity and shot noise, which is exacerbated by resist heating when using higher-density electron beams, resulting in interrupted writing processes and compromised line width precision.
Innovation Solution
A charged particle beam writing apparatus that divides the writing region into stripe regions, performs data conversion, and modulates the dose based on heat transfer from preceding regions to minimize resist heating, ensuring consistent line width precision by starting the writing process only when sufficient data is prepared and managing data transfer efficiently to reduce recovery interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher-density electron beam is used to increase current density, then writing time is reduced, but resist heating occurs causing line width precision degradation
Solution Approach 1:
The patent modulates the beam dose dynamically based on the cumulative dose already applied to adjacent regions. By changing the dose parameter adaptively according to heat accumulation, the system maintains writing speed while preventing resist heating-induced precision degradation.
Solution Approach 2:
The system calculates cumulative dose distribution across the writing region and uses this feedback to adjust the beam dose for subsequent writing areas. This closed-loop control prevents resist heating by reducing dose in regions where heat accumulation is detected, thereby maintaining line width precision.
2Manufacturing precision
If dose is modulated to account for heat transfer from other regions, then line width precision is maintained, but substrate temperature drops during recovery process causing precision loss
Solution Approach 1:
The patent performs preliminary actions during the recovery process by calculating and adjusting the beam dose to account for substrate temperature changes. Before resuming writing, the system pre-compensates for temperature drops by modifying dose parameters, ensuring continuous precision without interruption.
Solution Approach 2:
The system maintains continuous dose modulation throughout the writing process, including during recovery interruptions. By continuously adjusting the beam dose based on real-time temperature and cumulative dose information, the patent ensures uninterrupted precision control even when writing is temporarily suspended and resumed.
3Productivity
If data transfer speed is increased to prevent writing interruption, then writing continuity is improved, but data processing accuracy may be compromised
Solution Approach 1:
The patent segments the writing region into multiple sub-regions and processes data for each segment independently with appropriate dose modulation. This segmentation allows parallel data processing while maintaining accuracy, as each segment's data can be prepared and transferred without waiting for the entire writing dataset.
Solution Approach 2:
The system performs preliminary data conversion and dose calculation for upcoming writing regions before they are actually written. By preparing data in advance and storing it in buffer memory, the system ensures accurate data processing while maintaining writing continuity, as data transfer and processing occur in parallel with the writing of previous regions.
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 approach reduces the occurrence of recovery processes and maintains desired line width precision by modulating the dose according to heat transfer, thereby shortening writing time and improving pattern quality.
Implementation Method 1
determining for each of the temperature calculation regions the amount of temperature rise based on heat transfer from preceding temperature calculation regions in the writing order
Data Source
AI summary
A charged particle beam writing apparatus according to an embodiment starts a wiring operation when the sum of the amount of shot data stored in a buffer memory of a transfer control calculator, the amount of shot data being transferred by a transfer unit, and the amount of shot data stored in a buffer memory of a deflection control circuit reaches the amount of data for one stripe region.