Multi-Beam Charged Particle Writing Dose Modulation for Resist Heating
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Solution Overview
Problem
In multi-beam charged particle beam writing, resist heating occurs due to simultaneous irradiation of multiple beams, leading to inaccurate line width and residual correction issues in proximity effect correction.
Innovation Solution
A method involving a dose map creation, effective temperature calculation, and modulated dose calculation to correct for resist heating, using a dose map, effective temperature distribution, and back scattering coefficients to adjust the dose for each position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple beams are used for writing, then productivity is improved, but manufacturing precision deteriorates due to resist heating
Solution Approach 1:
The patent calculates and applies heating effect correction in advance before the actual writing process. By pre-calculating the temperature rise caused by multiple beam irradiation and determining the necessary dose modulation, the system compensates for resist heating effects before writing begins, thereby maintaining line width accuracy while using multiple beams for high-speed writing
Solution Approach 2:
The patent modifies the irradiation dose parameter based on calculated heating effects. By adjusting the dose distribution across different regions of the writing area according to predicted temperature rises, the system compensates for resist heating and maintains manufacturing precision despite using multiple beams for improved productivity
2Manufacturing precision
If dose correction for heating effect is applied, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the writing area into multiple stripe regions and further segments temperature calculation into mesh regions. This segmentation allows the heating effect correction to be applied in a structured, modular manner, managing computational complexity by breaking down the large-scale calculation into smaller, more manageable regional calculations
Solution Approach 2:
The patent introduces an effective temperature distribution map as an intermediary between the multiple beam irradiation and the dose correction process. This intermediary representation simplifies the complex thermal field into a usable format for dose modulation, making the correction system more manageable while maintaining accuracy
3Manufacturing precision
If proximity effect correction is performed first, then manufacturing precision is improved, but correction residuals increase when heating effect correction is subsequently applied
Solution Approach 1:
The patent performs heating effect correction in advance before proximity effect correction. By pre-calculating and applying dose modulation for heating effects, the system establishes a corrected baseline that accounts for temperature rises, allowing subsequent proximity effect correction to work on an already compensated dose distribution, thereby eliminating correction residuals
Solution Approach 2:
The patent separates the correction process into distinct sequential stages: first heating effect correction based on thermal considerations, then proximity effect correction based on electron scattering. This dimensional separation of correction concerns allows each type of correction to be optimized independently without interfering with the other, eliminating the residual correction problems that arise from simultaneous or reversed correction sequences
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
Reduces correction residuals and improves line width accuracy by accurately accounting for temperature rises caused by multiple beam irradiations.
Implementation Method 1
temperature rises due to heat caused by beam irradiations onto the surface of a target object
Data Source
AI summary
A charged particle beam writing apparatus, includes: an effective temperature calculation circuit configured to calculate, for each of mesh regions obtained by dividing each stripe region, a representative value of a temperature rise while a beam array region irradiated with multiple beams is passing through a mesh region of interest as a mesh region concerned, among temperature rises due to heat caused by beam irradiations onto the surface of the target object and affecting the mesh region of interest, as an effective temperature of the mesh region of interest; and a modulated dose calculation circuit configured to calculate a modulated dose at each position obtained by correcting a dose at each position defined in the dose map using a function using an effective temperature distribution map defining the effective temperature for each mesh region, an area density map for each position, and a back scattering coefficient for proximity effect correction.