Multi-Beam Exposure Segmentation for Imaging Error Tolerance
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Solution Overview
Problem
The performance of multibeam writing systems is limited by data rate processing and transfer into the pattern definition device, with specific requirements for the number of beamlets being a power of 2, which is not feasible in the range of interest, and optical imaging errors affecting the accuracy of patterns on the target.
Innovation Solution
The method involves writing stripes in consecutive passes, with each pass associated with partial grids of pattern pixels, allowing for additional redundancy and improved tolerance against imaging errors by exposing the same region with beamlets from different regions in the pattern definition device, and splitting the pixel grid into subgrids for sequential exposure, enabling flexible beamlet arrangements and reducing the impact of optical aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the number of beamlets is constrained to be a power of 2 for data processing, then data rate processing is simplified, but the flexibility of beamlet arrangement is reduced
Solution Approach 1:
The patent divides the pixel grid into multiple partial grids (e.g., 2x2, 3x3 segmentation) and processes them in sequential passes. This segmentation allows the system to work with smaller, more manageable beamlet groups in each pass while maintaining overall system flexibility. The aperture array can be reconfigured for each pass to match the specific partial grid requirements, eliminating the constraint that the total number of beamlets must be a power of 2.
Solution Approach 2:
The patent employs dynamic reconfiguration of the aperture array between passes. The aperture positions and configurations are adjusted adaptively for each pass based on the specific partial grid being processed. This dynamic adaptation allows the system to optimize beamlet arrangements for each sub-region independently, providing flexibility without being constrained by fixed power-of-2 beamlet numbers.
2Productivity
If a single pass exposes all stripes, then writing speed is maximized, but optical imaging errors affect the accuracy of patterns
Solution Approach 1:
The patent segments the exposure process into multiple passes, with each pass handling a specific partial grid of pixels. This segmentation allows optical errors to be localized and corrected independently for each pass. By processing different partial grids sequentially with potentially different aperture configurations, the system can compensate for optical imaging errors that would affect the entire field in a single-pass approach.
Solution Approach 2:
The patent uses partial grids that cover only portions of the total pattern area in each pass. This partial action approach allows the system to prioritize certain regions or apply different exposure parameters to different areas, enabling error correction and optimization for specific problem regions without compromising the overall writing speed significantly.
3Reliability
If multiple passes are used to write stripes, then tolerance against imaging errors is improved, but data rate processing complexity increases
Solution Approach 1:
The patent organizes pixels into partial grids that can be processed independently in sequential passes. This segmentation simplifies data rate processing for each pass by reducing the number of pixels that need to be managed simultaneously. The data processing complexity is distributed across multiple smaller passes rather than handled all at once, making the overall system more manageable while improving error tolerance.
Solution Approach 2:
The patent processes partial grids sequentially rather than attempting to process the entire pattern in one pass. This partial action approach reduces the data rate processing burden for each individual pass, as the system only needs to manage and transfer data for a subset of pixels at any given time. The cumulative effect of multiple passes achieves the complete pattern with improved error tolerance.
4Adaptability or versatility
If the aperture array is reconfigured for each pass, then coverage of pattern pixels is improved, but device complexity increases
Solution Approach 1:
The patent divides the aperture array into manageable groups that can be reconfigured for different partial grids. This segmentation allows the system to optimize aperture positions and configurations for specific regions without requiring complete reconfiguration of the entire array. The modular approach to aperture management reduces the practical complexity of reconfiguration while improving coverage of different pattern regions.
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 approach enhances the flexibility of the 'trotting mode' writing strategy, improves pixel addressing, and reduces the influence of optical errors, achieving better coverage and accuracy in pattern formation on the target while maintaining writing speed.
Implementation Method 1
illuminating said pattern definition means by means of an illuminating wide beam, which traverses the pattern definition means through said apertures, thus forming a patterned beam consisting of a corresponding plurality of beamlets
Implementation Method 2
forming said patterned beam into a pattern image on the location of the target, with the pattern image comprising the images of at least part of the plurality of apertures
Data Source
Figure 1~1A
Figure 2~4
Figure 3~17B
AI summary
In order to irradiate a target with a beam of energetic radiation formed by electrically charged particles, the beam is formed and imaged onto a target, where it generates a pattern image (pm) composed of a plurality of pixels (pm). The pattern image (pm) is moved along a path on the target over a region to be exposed, and this movement defines a number of stripes (s11, s21) covering said region in sequential exposures and having respective widths (y0) as measured across said main direction. The number of stripes (s11, s21) is written in at least two subsequent passes such that for each pass, the widths (y0) of the stripes of one pass combine into a cover of the total width of the region to be exposed; and each pass is associated with one of a number of partial grids (G1, G2) of pattern pixels which are exposable during the respective pass. The mutually different partial grids (G1, G2) combine to the complete plurality of pattern pixels which compose the region to be exposed.