Multi Charged Particle Beam Writing Distortion Compensation
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Solution Overview
Problem
In multi-charged particle beam writing systems, achieving high accuracy in pattern formation is hindered by distortion in the optical system, leading to challenges in adjusting irradiation positions and correcting field distortion, which complicates the optimization of parameters like resolution and focus depth.
Innovation Solution
A method and apparatus that calculate initial shot positions considering distortion, adjust condition positions within predefined regions, and calculate irradiation times based on area density to ensure precise beam alignment and pattern formation, using a control grid and deflection control units to maintain accurate beam positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the lens condition is changed to adjust pattern dimension, then the pattern size can be adjusted, but pattern rotation or field distortion occurs
Solution Approach 1:
The patent pre-calculates distortion amounts for each shot position and stores them in a distortion amount map before actual pattern writing. This preliminary action allows the system to compensate for optical distortions by adjusting shot positions based on pre-computed values, thereby maintaining pattern shape stability while achieving dimension accuracy without requiring lens condition changes.
Solution Approach 2:
The patent changes the parameter being adjusted from lens conditions to shot position coordinates. Instead of modifying optical system parameters that cause distortion, the system adjusts the digital shot position parameters using pre-calculated distortion compensation values, thus achieving dimension control without inducing shape distortion.
2Manufacturing precision
If mechanical rotation adjustment is performed to correct distortion, then irradiation position accuracy can be improved, but the required rotation precision is unrealistically high
Solution Approach 1:
The patent replaces the mechanical rotation adjustment system with a digital calculation and control system. Instead of using mechanical components to physically rotate or reposition the optical system with nm-level precision, the system uses computational methods to calculate distortion amounts and adjusts shot positions through digital coordinate transformations, eliminating the need for ultra-precise mechanical adjustment mechanisms.
3Manufacturing precision
If field distortion is corrected through precise optical system design, then distortion can be reduced, but manufacturing accuracy of nm or below is required which is unrealistic
Solution Approach 1:
The patent applies preliminary anti-action by pre-calculating the distortion amounts that will occur during pattern writing and storing these values in a distortion amount map. The system then uses these pre-computed values to compensate for distortions by adjusting shot positions in the opposite direction of the expected distortion, thereby correcting field distortion effects without requiring ultra-precise optical manufacturing.
4Manufacturing precision
If multiple correction systems are added to reduce distortion, then distortion correction capability is improved, but apparatus complexity and burden increase excessively
Solution Approach 1:
The patent extracts the distortion correction function from the physical optical system and implements it as a separate digital processing step. By separating the correction mechanism from the optical writing system and implementing it through software-based shot position calculation using pre-stored distortion maps, the patent avoids adding complex physical correction hardware while achieving effective distortion compensation.
5Manufacturing precision
If parameter optimization is attempted after manufacturing, then writing accuracy can be improved, but parameters are intricately related making optimization difficult and time-consuming
Solution Approach 1:
The patent performs preliminary action by pre-calculating distortion amounts for all shot positions and storing them in a distortion amount map before actual pattern writing begins. This pre-computation eliminates the need for time-consuming iterative optimization during operation, as the system can directly use the pre-prepared distortion compensation data to achieve high writing accuracy immediately.
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 effectively suppresses pattern shape changes due to optical distortions, enabling high-precision pattern writing by accounting for positional deviations and optimizing beam irradiation times, thus improving the overall accuracy and efficiency of multi-beam writing processes.
Implementation Method 1
each unblocked beam is reduced by an optical system and deflected by a deflector so as to irradiate a desired position on a target object
Implementation Method 2
each unblocked beam is reduced by an optical system
Data Source
AI summary
A multi charged particle beam writing method includes calculating first shot positions of multiple beams, each of which includes a distortion amount of an irradiating corresponding beam, in a case of irradiating each beam, based on control grid intervals, calculating first condition positions based on a pre-set condition, each of which is arranged in a corresponding first region surrounded by closest second shot positions of 2×2 in length and width of the first shot positions, calculating, for each of second regions respectively surrounded by closest second condition positions of the first condition positions, an area density of a figure pattern in overlapping with a second region concerned, calculating an irradiation amount or an irradiation time of each beam whose corresponding first shot position is in a corresponding second region, based on an area density, and writing a pattern by irradiating a beam of the calculated irradiation amount or time.