Multi-Column Electron Beam Exposure Line Width Uniformity
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Solution Overview
Problem
Multi-column electron beam exposure apparatuses face challenges in achieving uniform line widths among column cells due to variations in aberration of the electron optical system, effective current density, aperture size, and pattern density, which existing correction methods, including proximity effect correction, fail to adequately address.
Innovation Solution
An electron beam exposure method that adjusts the exposure time of each column cell by using correction parameters to align the relationship between exposure intensity and line width with a reference column cell, allowing for uniform line widths even when proximity effect correction is performed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If exposure time is changed for proximity effect correction, then line width uniformity is improved, but line width variation among column cells cannot be prevented
Solution Approach 1:
The patent applies local quality by determining correction parameters individually for each column cell based on its specific characteristics (aberration, current density, aperture size). Each column cell receives customized exposure time corrections rather than a uniform correction, allowing local optimization that maintains both line width uniformity and consistency across different column cells
Solution Approach 2:
The patent changes parameters by introducing multiple correction parameters (including but not limited to proximity effect correction parameters) to adjust exposure time. By modifying the exposure time parameter based on measured line width data and calculated correction values, the system achieves uniform line width across all column cells while maintaining reliability
2Manufacturing precision
If proximity effect correction calculation is performed with specific parameters for each column cell, then line width uniformity is improved, but data generation complexity and time increase
Solution Approach 1:
The patent applies universality by using a standardized correction parameter determination process that can be applied to all column cells. The same measurement and calculation methodology is universally applied across different column cells, reducing complexity through method standardization while still accounting for individual cell characteristics
Solution Approach 2:
The patent simplifies complexity by changing from a complex multi-parameter approach to a more streamlined correction parameter determination. By focusing on key parameters (exposure time, line width measurements) and using systematic calculation methods, the patent reduces data generation complexity while maintaining correction accuracy
3Ease of operation
If three parameters are used for proximity effect correction calculation, then calculation is simplified, but degree of freedom is insufficient to correct multiple causes of line width variation
Solution Approach 1:
The patent applies local quality by determining correction parameters individually for each column cell based on its specific characteristics (aberration, current density, aperture size). This localized approach provides sufficient degree of freedom to correct multiple causes of line width variation while maintaining practical operability through automated measurement and calculation
Solution Approach 2:
The patent applies dynamics by making the correction parameters adaptive rather than fixed. The parameters are dynamically determined based on actual measurements from each column cell, allowing the system to adapt to varying conditions and correct multiple sources of line width variation with appropriate flexibility
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 method effectively corrects line width variations among column cells by generating exposure data that accounts for the specific conditions of each column cell, reducing the complexity and time required for data generation and facilitating practical management of exposure data.
Implementation Method 1
a micropattern has been drawn on a photomask by exposure using an electron beam exposure apparatus
Implementation Method 2
a so-called proximity effect in which a line width of a pattern varies due to a change in backscattering amount of the electron beam according to the pattern density
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
In a multi-column electron beam exposure apparatus for performing exposure treatment in parallel by arranging a plurality of column cells on a wafer, a relationship between exposure intensity and a line width for each column cell is obtained (Steps S41 and S44). Then, correction parameters are obtained, which allow a relationship between exposure intensity and a line width for a correction target column cell to coincide with a relationship between exposure intensity and a line width for a reference column cell selected from among the plurality of column cells (Steps S43 and S46). Thereafter, exposure time of each column cell is obtained by correcting the exposure time of the reference column cell based on the correction parameters thus obtained (Steps S30 and S40).