Bi-Directional Double-Pass Multi-Beam Writing for Precision Lithography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current multi-beam writing technologies face challenges in achieving high Local and Global Critical Dimension Uniformity (LCDU and GCDU) and pattern placement accuracy, with limitations in reducing misplacements and resist heating, especially when dealing with small feature sizes and complex patterns.
Innovation Solution
The implementation of a 'Bi-Directional-Double-Pass' multi-beam writing method, which involves writing stripes in multiple sweeps with alternating directions, utilizing an air-bearing X-Y vacuum stage to enable high velocity in both directions, and overlapping stripes to reduce stage noise and beam array field distortions, thereby improving exposure dose uniformity and local beam-to-substrate error averaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If single-direction stripe writing is used, then writing speed is maintained, but stripe boundary errors and placement accuracy deteriorate
Solution Approach 1:
The writing process is segmented into multiple passes with alternating directions. Instead of writing all stripes in one direction, the method divides the work into forward passes and backward passes, where each pass writes stripes in alternating directions. This segmentation allows error distribution and cancellation, improving placement accuracy while maintaining overall writing speed through parallel processing capabilities.
Solution Approach 2:
The invention applies the inversion principle by reversing the writing direction in alternating passes. While conventional methods write all stripes in one direction, this invention writes stripes in opposite directions in successive passes, causing systematic errors to cancel out. The stage noise and beam array field distortions that affect one direction are counteracted by the reverse direction writing, significantly reducing stripe boundary errors.
2Reliability
If conventional multi-beam writing is used, then exposure is completed, but local resist and substrate heating increases
Solution Approach 1:
The invention implements periodic action by alternating the writing direction in successive passes. Instead of continuous unidirectional writing, the system periodically reverses direction, creating a rhythmic pattern of forward and backward passes. This periodic reversal prevents continuous heating in one location by distributing the thermal load across different spatial and temporal patterns, allowing heat dissipation between passes while maintaining exposure quality.
3Productivity
If high stage velocity is used, then writing time is reduced, but stage noise and beam array field distortions increase
Solution Approach 1:
The invention converts the harmful effect of stage noise and beam array field distortions into a beneficial outcome through alternating direction writing. The systematic errors introduced by high-velocity stage movement are transformed from cumulative defects into canceling patterns. By writing in opposite directions, the noise and distortions that plague one pass are counteracted in the next pass, allowing high writing speeds to be maintained without sacrificing stripe boundary accuracy.
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 significantly enhances multi-beam writing performance by reducing stripe boundary errors, local resist and substrate heating, and achieving superior LCDU, GCDU, and registration accuracy without increasing exposure field write time.
Implementation Method 1
utilizing an air-bearing X-Y vacuum stage to enable high velocity in both directions
Implementation Method 2
illuminating said pattern definition device by means of an illuminating wide beam, which traverses the pattern definition device through said apertures thus forming a patterned beam consisting of a corresponding plurality of beamlets
Data Source
AI summary
To irradiate a target with a beam of energetic electrically charged particles, the beam is formed and imaged onto a target, where it generates a pattern image composed of pixels. The pattern image is moved along a path on the target over a region to be exposed, and this movement defines a number of stripes covering said region in sequential exposures and having respective widths. The number of stripes is written in at least two sweeps which each have a respective general direction, but the general direction is different for different sweeps, e.g. perpendicular to each other. Each stripe belongs to exactly one sweep and runs substantially parallel to the other stripes of the same sweep, namely, along the respective general direction. For each sweep the widths, as measured across said main direction, of the stripes of one sweep combine into a cover of the total width of the region.