Multi-Beamlet Lithography Exposure Strategy
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Solution Overview
Problem
Current charged particle beam lithography systems face challenges in achieving smaller critical dimensions while maintaining sufficient wafer throughput, requiring a large number of beamlets and complex movement strategies that lead to incomplete exposure and variations in beamlet performance.
Innovation Solution
A method and system that utilize a charged particle multi-beamlet system with optimized beamlet arrangement and movement strategies, including grouping beamlets and using a virtual grid for efficient exposure, where the distance between adjacent scan lines is adjusted to ensure full coverage with minimal stepwise movement, and the beamlets are deflected in a coordinated manner to average out variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large number of beamlets are used to achieve smaller critical dimensions, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the exposure task into multiple beamlets arranged in a two-dimensional array, where each beamlet independently exposes a portion of the target. This segmentation allows achieving smaller critical dimensions through coordinated action of multiple beamlets while managing system complexity through systematic control approaches.
Solution Approach 2:
The patent transitions from one-dimensional beam scanning to two-dimensional beamlet arrays, adding spatial dimensionality to the exposure system. This enables more efficient coverage and smaller critical dimensions by utilizing both horizontal and vertical beamlet arrangements simultaneously.
2Manufacturing precision
If a large number of beamlets are used to achieve smaller critical dimensions, then manufacturing precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent combines multiple beamlets into a coordinated array system where beamlets are controlled in groups or patterns rather than individually. This merging approach simplifies operation by reducing the control burden from managing each beamlet separately to managing beamlet patterns or groups as unified entities.
Solution Approach 2:
The patent employs periodic scanning patterns and rhythmic beamlet activation sequences to simplify control. By using regular, repeating exposure patterns, the system makes complex multi-beamlet operation more manageable through predictable, cyclical control routines.
3Manufacturing precision
If complex movement strategies are used to coordinate beamlets, then manufacturing precision is improved, but productivity deteriorates
Solution Approach 1:
The patent implements continuous exposure patterns where beamlets operate without interruption or idle movement. By maintaining constant beamlet activity and eliminating unnecessary repositioning, the system achieves both exposure precision and high wafer throughput through uninterrupted productive action.
Solution Approach 2:
The patent pre-positions beamlets in optimized arrays and pre-plans exposure patterns before actual exposure begins. This preliminary arrangement of beamlets in precise two-dimensional configurations eliminates the need for complex real-time movement adjustments during exposure, thereby maintaining both precision and productivity.
4Manufacturing precision
If beamlets are densely arranged to improve resolution, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent employs asymmetric beamlet spacing and arrangement patterns that optimize resolution without requiring uniform dense packing in all directions. By using non-uniform, asymmetric configurations, the system achieves high feature size precision while reducing the overall complexity of beamlet positioning and control.
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 enables efficient and uniform exposure of large areas with reduced complexity in movement, improving throughput and reducing the effects of beamlet variations, thereby achieving smaller critical dimensions and higher wafer throughput.
Implementation Method 1
a charged particle beam column for exposing a target. The charged particle beamlets are scanned over the target while being modulated
Implementation Method 2
The modulation of the beamlets is performed by blanking or blocking beamlets to effectively switch the beamlets on and off
Implementation Method 3
By modulating the beam (or beams in multi-beam systems), individual grid cells in a rasterized virtual grid may be exposed or not exposed to write the desired pattern on to the target
Data Source
Figure 1
Figure 2~3B
Figure 4
AI summary
The invention relates to amethod ofexposing a target by means of a plurality of beamlets. First, a plurality of beamlets is provided. The beamlets are arranged in an array. Furthermore, a target to be exposed is provided. Subsequently, relative movement in a first direction between the plurality of beamlets and the target is created. Finally, the plurality ofbeamlets is moved in a second direction, such that each beamlet exposes a plurality of scan lines on the target. The relative movement in the first direction and the movement of the plurality of beamlets in the second direction are such that the distance between adjacent scan lines exposed by the plurality of beamlets is smaller than a projection pitch P proj,X in the first direction between beamlets of the plurality of beamlets in the array.