Offset Deflection Calculation for Variable-Shaped Electron Beam Lithography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for calculating the offset deflection amount in variable-shaped electron beam lithography are insufficient for achieving high precision, especially with increased integration density of semiconductor patterns, leading to misalignment issues due to differences in shaping positions between aperture plates.
Innovation Solution
A method involving the formation of reference images and convolution synthesis images using design data and optical images of figures shaped by aperture plates, with center-of-gravity position calculations to determine offset deflection amounts, ensuring precise alignment of reference positions across different figure types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used to calculate offset deflection amount, then the calculation process is simple, but the alignment precision is insufficient for fine patterns with increased integration density
Solution Approach 1:
The patent performs preliminary actions by creating convolution reference images from aperture design data before actual pattern formation. These reference images are used to calculate center-of-gravity positions in advance, enabling precise offset deflection amount calculation before the actual lithography process begins. This preliminary preparation resolves the contradiction by establishing accurate reference data that simplifies subsequent alignment operations while maintaining high precision.
Solution Approach 2:
The patent introduces convolution reference images and center-of-gravity position calculations as intermediary elements between the aperture plates and the final pattern formation. These intermediaries serve as reference standards that mediate the alignment process, allowing precise measurement and calculation of offset deflection amounts without requiring direct complex measurements of the actual patterns. This intermediary approach enables high precision while keeping the calculation process manageable.
2Adaptability or versatility
If aperture plates are used to shape beams for different figure types, then various pattern shapes can be formed, but misalignment occurs due to differences in shaping positions
Solution Approach 1:
The patent implements a feedback mechanism by calculating center-of-gravity positions from optical images of formed patterns and comparing them with design data. Based on this feedback, the offset deflection amounts are calculated and adjusted for each figure type. This feedback loop ensures that despite different shaping positions in aperture plates for various pattern shapes, the final patterns are precisely aligned by compensating for position differences through calculated offset values.
Solution Approach 2:
The patent applies local quality by calculating specific offset deflection amounts for each figure type based on its unique characteristics. Instead of using a uniform alignment approach, the system determines tailored offset values for different pattern shapes (rectangles, triangles, circles, etc.) by analyzing their specific center-of-gravity positions. This localized approach maintains manufacturing precision while preserving the ability to form diverse pattern shapes.
3Adaptability or versatility
If beam positions are shaped at different locations on aperture plates for different figures, then various figure types can be created, but reference positions become misaligned
Solution Approach 1:
The patent creates copies of reference information by generating convolution reference images from aperture design data for each figure type. These reference images serve as ideal templates that are compared with actual optical images. By copying the expected pattern characteristics into reference data, the system can accurately measure and correct reference position deviations, maintaining high measurement precision while supporting diverse figure types.
Data Source
AI summary
A method of acquiring an offset deflection amount for a shaped beam, includes forming reference images of first and second figures which can be shaped by first and second aperture plates placed on a lithography apparatus, and a reference image of a mark; forming first and second convolution reference images based on the reference images of the mark and of the first and second figures; scanning over the mark with charged particle beams shaped into the first and second figures to acquire optical images of the first and second figures; forming first and second convolution synthesis images based on the first convolution reference image and respectively the optical images of the first and second figures; and calculating an offset deflection amount for the charged particle beam shaped into the second figure to match reference positions of the first and second figures based on center-of-gravity positions of the first and second convolution synthesis images.