Laser Beam Combiner Layout for Gap-Free Lithography Exposure
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Solution Overview
Problem
Existing lithographic apparatuses face limitations in increasing wafer throughput and power delivery due to the need for multiple exposure passes and the power limitations of single laser systems, necessitating the combination of multiple laser beams for enhanced capabilities.
Innovation Solution
A gas discharge laser system comprising multiple laser chamber modules and a beam combiner that combines laser beams using reflective surfaces, beveled edges, adjustable apertures, and rotating mirrors to propagate beams in a common direction, minimizing gaps and enabling simultaneous or alternating pulse operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple laser beams are combined to increase power and repetition rates, then productivity and power delivery are improved, but device complexity increases due to the need for beam combining optics and synchronization mechanisms
Solution Approach 1:
The patent combines multiple laser beams (e.g., two KrF laser beams) into a single common direction using beam combining optics, allowing simultaneous or alternating delivery of laser pulses to the wafer. This merging of separate laser systems enables increased power delivery and repetition rates while maintaining a unified beam path for exposure.
Solution Approach 2:
The patent employs dynamic switching mechanisms such as rotating mirrors or acousto-optic modulators to alternately direct different laser beams into the common beam path. This dynamic control allows flexible switching between lasers at different wavelengths or modes, enabling adaptive power and wavelength delivery without requiring permanent physical reconfiguration.
2Productivity
If multiple laser beams are combined to deliver higher power in a single pass, then the number of exposure passes is reduced, but manufacturing precision may be affected by beam alignment and overlap challenges
Solution Approach 1:
The patent introduces beam combining optics and alignment intermediaries that facilitate precise merging of multiple laser beams into a common path. These intermediary optical elements ensure accurate spatial and angular alignment of beams from different lasers, maintaining the required precision for multi-wavelength exposure in a single pass.
Solution Approach 2:
The patent controls and adjusts critical parameters such as beam wavelength, power, timing, and spatial position to optimize both productivity and precision. By dynamically tuning these parameters, the system achieves accurate beam overlay and synchronization, enabling high-speed single-pass exposure without sacrificing manufacturing precision.
3Power
If laser beams are combined with minimal gaps between them, then power density is improved, but the difficulty of detecting and measuring beam alignment increases
Solution Approach 1:
The patent employs alignment intermediaries such as reference marks, alignment lasers, or optical sensors that facilitate precise measurement and control of beam positions. These intermediary tools enable accurate detection of beam alignment even when beams are closely spaced, allowing optimization of power density without sacrificing measurability.
Solution Approach 2:
The patent utilizes advanced sensing and control systems that can detect and measure beam parameters (position, angle, intensity) with high precision. By implementing real-time feedback and adjustment mechanisms, the system maintains optimal beam alignment and power density while providing sufficient measurement capability for quality 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
The system achieves increased power and repetition rates, reducing the need for multiple passes and enhancing wafer throughput by combining laser beams effectively, allowing for multiple wavelength exposure 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 beveled edge forming an acute angle with the beveled edge, the mirror being arranged such that the second beam of laser radiation propagates in the common direction immediately adjacent to the acute angle
Implementation Method 3
an aperture arranged such that the second beam passes through the aperture and the aperture limits a dimensional extent of the second beam of laser radiation so that the second beam of laser radiation does not impinge on the acute angle
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.