Charged Particle Beam Writing Apparatus Dose Equation Selection
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Solution Overview
Problem
Conventional electron beam writing methods require longer writing times due to excessive doses in regions far from the figure edge, as they do not adequately account for dose distribution beyond the forward scattering radius, leading to inefficient pattern writing and increased irradiation time.
Innovation Solution
A beam writing apparatus and method that select a dose equation for each small region of a target workpiece, virtually divided into mesh-like areas, to calculate and adjust the dose, reducing excessive doses and improving throughput by shortening writing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single dose equation is used for calculating beam dose across the entire writing region, then the calculation method is simple and easy to implement, but the dose distribution becomes non-optimized leading to excessive doses in inner figure regions and longer writing time
Solution Approach 1:
The writing region is divided into multiple small regions (e.g., 3x3 grid) and different dose equations are applied to different regions. Inner figure regions use one dose equation while outer regions use another, allowing optimized dose calculation for each area rather than using a single equation for the entire region.
Solution Approach 2:
Different dose equations are selected based on the local characteristics of each small region. The dose calculation method is adapted to match the specific requirements of inner figure regions versus outer regions, achieving local optimization of dose distribution and writing efficiency.
2Manufacturing precision
If the dose is set to ensure threshold value at figure edge, then pattern resolution is maintained, but regions sufficiently distant from figure edge receive excessive dose causing longer irradiation time
Solution Approach 1:
The dose equation selection is based on local position characteristics. Inner figure regions use a dose equation optimized for maintaining pattern resolution at edges, while outer regions sufficiently distant from figure edges use a different equation that reduces excessive dose and shortens irradiation time.
Solution Approach 2:
The patent applies partial optimization by using different dose strategies for different regions. Full dose is applied where needed for pattern resolution at figure edges, while reduced dose is applied in outer regions where full dose is not necessary, avoiding excessive irradiation time.
3Productivity
If dose equations are optimized for different regions, then writing time is reduced and throughput is enhanced, but the system complexity increases due to multiple dose equations and region division
Solution Approach 1:
The writing region is segmented into a grid of small regions (e.g., 3x3 division), with each region assigned a specific dose equation. This systematic segmentation provides a structured approach to managing multiple dose equations, balancing complexity with implementability.
Solution Approach 2:
The system dynamically selects appropriate dose equations based on the characteristics of each small region. This dynamic adaptation allows the system to optimize dose calculation for each region while maintaining a unified overall control framework, managing complexity through adaptive selection rather than fixed complex algorithms.
Data Source
AI summary
A beam writing apparatus according to an embodiment includes a selection unit configured to select a dose equation from a plurality of dose equations for calculating a dose of a beam, for each small region of a plurality of small regions made by virtually dividing a writing region of a target workpiece into mesh-like regions, a dose calculation unit configured to calculate a dose of a beam which is shot into a small region of the plurality of small regions, by using a selected dose equation, for the each small region, and a writing unit configured to write a desired pattern in the small region, by using a calculated dose, for the each small region.