DAC Calibration Mapping for Precise Charged-Particle Deflection
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Solution Overview
Problem
Existing methods for correcting non-linearity errors in digital-to-analog converters (DACs) of charged-particle beam systems are inefficient and resource-intensive, failing to address individual DAC variances and leading to inaccurate beam positioning and inspection image errors.
Innovation Solution
A method is provided to characterize the non-linearity behavior of each DAC in a charged-particle inspection system, establishing a lookup table for each DAC to determine error-correcting digital inputs, and applying these inputs to generate error-compensated outputs, thereby improving precision and reducing resource waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional error correction methods are used for DACs in charged-particle beam systems, then the correction process is simple, but the beam positioning accuracy deteriorates due to non-linearity errors
Solution Approach 1:
The patent applies preliminary action by establishing mapping relationships for each DAC before the inspection system operates. During initialization, the system determines non-linearity characteristics of each DAC and creates correction mappings that are stored and applied during actual beam manipulation. This pre-characterization approach ensures high beam positioning accuracy without adding complexity to the operational error correction process.
2Manufacturing precision
If individual DAC calibration is performed for each DAC, then the beam positioning accuracy improves, but the time and resources required for system initialization increase
Solution Approach 1:
The patent applies segmentation by treating each DAC independently rather than calibrating the entire deflector system as a single unit. Each DAC is individually characterized to determine its specific non-linearity mapping relationship. This segmented approach allows parallel processing of multiple DACs during initialization and enables selective calibration only when needed, reducing overall initialization time while maintaining high precision for each individual deflector.
3Reliability
If non-linearity correction is applied to each DAC, then the inspection image accuracy improves, but the computational resources and processing time increase
Solution Approach 1:
The patent minimizes computational resource consumption during operation by performing all non-linearity characterization and mapping relationship establishment during system initialization. Once the mapping relationships are determined and stored, the actual beam manipulation and inspection processes use these pre-computed mappings without requiring intensive real-time calculations. This separates the computationally intensive calibration phase from the operational phase, ensuring high inspection image accuracy while reducing ongoing energy and computational requirements.
Data Source
AI summary
A method for controlling deflectors of a charged-particle inspection system is disclosed. The method comprises establishing a mapping relationship for each digital-to-analog converter (DAC) of a plurality of DACs included in a charged-particle inspection system, the mapping relationship characterizing non-linearity behavior of each of the DACs, determining target control signals for manipulating deflectors of the charged-particle inspection system, determining, for each DAC of the plurality of DACs, an error correcting digital input based on a corresponding target control signal among the target control signals and the corresponding mapping relationship, and inputting the corresponding error correcting digital input to each of the DACs to enable each of the DACs to generate a corresponding error compensated output.