Multiple Charged Particle Beam Dose Correction for Resist Heating
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Solution Overview
Problem
In multiple-beam writing, resist heating occurs due to high irradiation energy density, leading to inaccurate line width accuracy, and existing methods require extensive calculations to account for temperature rise from each shot and beam, which is impractical for a large number of beams.
Innovation Solution
A multiple charged particle beam writing apparatus and method that divides the writing region into mesh regions, calculates a representative dose value for each mesh, uses a convolution process to predict temperature rise, and adjusts beam doses to correct for resist heating without accumulating influence from each shot and beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple beams are used for writing, then throughput is significantly increased, but resist heating occurs due to high irradiation energy density
Solution Approach 1:
The writing region is divided into multiple stripe regions, and each stripe region is further divided into mesh regions. This segmentation allows the system to process and correct temperature effects in smaller, manageable units rather than treating the entire writing area as a single region, enabling more precise local dose adjustments.
Solution Approach 2:
The system calculates effective temperature based on cumulative dose from multiple beams and adjusts the dose parameters accordingly. By changing the dose parameter as a function of calculated effective temperature, the system compensates for resist heating effects while maintaining high throughput multiple-beam writing.
2Manufacturing precision
If dose correction is performed by accumulating temperature rise influence for each shot and beam, then line width accuracy is improved, but calculation complexity becomes enormous
Solution Approach 1:
The system merges the dose information from multiple beams by calculating a cumulative effective temperature for each mesh region. Instead of tracking each beam and shot separately, the approach combines their thermal effects into a single effective temperature value that represents the total heating influence, significantly reducing calculation complexity.
Solution Approach 2:
The system performs preliminary calculation of effective temperature and dose correction amounts before actual writing. By pre-calculating the cumulative thermal effects and determining correction doses in advance, the system avoids the need for complex real-time calculations during the writing process, thereby reducing overall computational burden.
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 corrects resist heating by optimizing beam doses, ensuring accurate line width precision without the computational burden of individual shot calculations, particularly suitable for multiple-beam writing processes.
Implementation Method 1
irradiate a writing region on a surface of a target object with multiple charged particle beams
Implementation Method 2
high irradiation energy density
Implementation Method 3
thermal spread function representing thermal spread generated by the plurality of mesh regions
Data Source
AI summary
The disclosure relates to a multiple charged particle beam writing apparatus that includes a dose representative value calculator that determines a representative dose for each mesh region irradiated by multiple beams. A calculation processor computes the temperature rise in a mesh region of interest due to beam irradiation, using a convolution of the dose values and a thermal spread function. An effective temperature calculator repeats this process while shifting the processing region along the stripe to obtain multiple temperature rises of the mesh area of interest and calculate a representative value of the multiple temperature rises as an effective temperature of the mesh area of interest. Based on the effective temperature, a dose corrector adjusts the beam doses to compensate for resist heating effects.