Laser Beam Combining for Single-Pass Lithography Exposure
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Solution Overview
Problem
Current lithographic apparatuses require multiple exposure passes to achieve desired patterns on wafers, which reduces throughput and limits the power that can be delivered to the wafer.
Innovation Solution
A gas discharge laser system that combines two laser beams, each generated by a separate chamber module, using a beam combiner to propagate them in a common direction, thereby increasing power and reducing the need for multiple exposure passes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple exposure passes are used to achieve desired patterns on wafers, then manufacturing precision is improved, but productivity deteriorates
Solution Approach 1:
The patent combines multiple laser beams (e.g., two KrF laser beams) into a single beam path using optical combining techniques. This allows multiple exposure passes to be performed simultaneously or in rapid succession through a single scanner, thereby maintaining pattern quality while significantly increasing wafer throughput by eliminating the need for sequential processing of multiple separate beam lines.
2Device complexity
If a single laser is used, then device complexity is reduced, but power deteriorates
Solution Approach 1:
The patent merges multiple high-power laser beams into a common propagation path using beam combiners and optical elements. This allows the system to achieve higher total power delivery (e.g., combining two 150W KrF lasers to deliver 300W) while maintaining a relatively simple single-beam scanner architecture, thus resolving the contradiction between power requirements and device complexity.
3Power
If multiple laser beams are combined, then power is improved, but device complexity increases
Solution Approach 1:
The patent employs intermediary optical elements such as beam combiners, mirrors, and optical delay lines to facilitate the merging of multiple laser beams. These intermediary components enable sophisticated beam combination and synchronization while maintaining modularity, allowing the system to achieve high power delivery without proportionally increasing overall system complexity.
Solution Approach 2:
The patent divides the laser system into separate modular laser chambers (e.g., two independent KrF laser chambers) that can be operated independently and then combined. This segmentation allows each laser module to be optimized and maintained separately, reducing the complexity impact of having multiple beams while still achieving high total power through their combination.
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
The system effectively doubles the repetition rate and power delivery to the wafer, allowing for increased throughput and the ability to achieve multiple wavelength exposures in a single pass.
Implementation Method 1
the mirror being arranged such that the first beam of laser radiation reflects off of the reflective surface in the common direction
Implementation Method 2
A gas discharge laser system that combines two laser beams, each generated by a separate chamber module, using a beam combiner to propagate them in a common direction, thereby increasing power and reducing the need for multiple exposure passes
Data Source
AI summary
Apparatus for and methods of combining multiple, i.e., two or more laser beams to reduce even to the point of elimination a transverse gap between the two or more beams caused, for example, by a space between a coating on a surface of the mirror and the edge of the mirror, or by optic geometry, is avoided.