Beam Column Array Alignment Using Intermediary Marks
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Solution Overview
Problem
Conventional electron beam columns face challenges in accurately registering multiple beams, leading to insufficient placement accuracy in future generation lithography and inspection tools, with existing techniques being impractical, time-consuming, or inaccurate.
Innovation Solution
An apparatus and method for calibrating multiple beams in a beam array using alignment marks located beneath the lenses, with electronics determining beam centroid positions to align the beams relative to each other and a target, enabling precise alignment through scanning and data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional alignment techniques are used for multiple beam columns, then alignment can be performed, but the process is too time-consuming and inaccurate for production tools
Solution Approach 1:
The patent introduces an intermediary alignment mark structure that mediates between the beam columns and the alignment process. The alignment marks are positioned at known locations relative to each other and serve as reference points that enable rapid, accurate measurement of beam positions without requiring complex iterative alignment procedures between each beam pair.
Solution Approach 2:
The patent uses a replicated pattern of alignment marks that can be scanned by multiple beams simultaneously. Instead of performing pairwise alignment between each beam, the system copies the same alignment mark pattern across the field and uses all beams to scan these marks in parallel, dramatically reducing alignment time while maintaining nanometer-level accuracy.
2Productivity
If parallel beam arrays are used to increase throughput, then productivity improves, but beam-to-beam calibration becomes extremely difficult due to variations in assembly tolerances and tip placement
Solution Approach 1:
The system performs self-calibration by having each beam scan the alignment marks and automatically determine its own centroid position relative to the known mark locations. The electronics process the scan data to calculate beam positions and alignment corrections without requiring manual intervention or complex external calibration equipment, enabling the parallel beam array to self-correct for assembly tolerances and tip placement variations.
Solution Approach 2:
The patent implements a feedback mechanism where the scan results from alignment marks are fed back to determine beam centroid positions and calculate alignment corrections. This closed-loop approach allows the system to measure actual beam positions, compare them to ideal positions, and apply corrections to achieve nanometer-level alignment accuracy across the parallel beam array.
3Manufacturing precision
If nanometer level placement of lens apertures is achieved, then manufacturing precision improves, but variations in assembly tolerances and tip placement still require complex alignment procedures
Solution Approach 1:
The alignment marks serve as an intermediary reference system that decouples the manufacturing precision of the beam columns from the final alignment accuracy. Even with nanometer-level aperture placement, the marks provide a stable, known reference framework that simplifies the alignment procedure by providing explicit geometric references that all beams can use to determine their relative positions.
Data Source
AI summary
A beam column array included alignment marks within to enable alignment of beams with respect to each other. Specifically, the array includes an array of beam columns, each column having at least once lens. A plurality of alignment marks are located beneath the lens. A method of using the array includes: scanning a plurality of beams in a beam column array over a plurality of alignment marks; and determining beam centroid positions of the beams with respect to each other based on data from the scanning.