EUV Source Stabilization via Crucible Bumps and Eaves
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Solution Overview
Problem
EUV lithography systems face instability and reduced EUV light intensity due to the accumulation of tin debris, which causes defocusing of the laser spot and fluctuations in EUV light generation, affecting the precision and efficiency of semiconductor manufacturing.
Innovation Solution
A rotating crucible with strategically placed bumps and an eave is used to manage the flow of metal debris, converting turbulent flow to laminar flow and directing debris to a catcher, maintaining a stable laser spot size and EUV light intensity by recycling metal debris back to the target region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a laser beam is focused onto a metal target to generate EUV light, then EUV light intensity is improved, but tin debris accumulates causing laser spot defocusing and EUV light intensity fluctuations
Solution Approach 1:
The invention extracts and removes tin debris from the laser target region using a debris removal system that includes a gas flow to carry debris away from the target area, preventing accumulation and maintaining stable EUV light generation
Solution Approach 2:
The invention introduces a gas intermediary (such as nitrogen or argon gas) that mediates between the laser-target interaction and debris accumulation by carrying tin debris away from the focal region, thereby maintaining laser spot focus and EUV light intensity stability
2Productivity
If the laser spot size fluctuates due to tin debris accumulation, then manufacturing precision deteriorates, but continuing operation maintains productivity
Solution Approach 1:
The invention performs preliminary debris removal by establishing a gas flow system that continuously clears tin debris from the target region before significant accumulation occurs, preventing laser spot defocusing and maintaining manufacturing precision throughout operation
Solution Approach 2:
The invention implements a feedback mechanism where EUV light intensity is monitored and used to detect debris accumulation, triggering increased gas flow or other corrective actions to restore laser focus and maintain manufacturing precision
3Reliability
If the crucible rotates at high speed to manage metal flow, then debris control is improved, but device complexity increases
Solution Approach 1:
The invention merges the debris removal function with the crucible rotation system by integrating gas flow channels and debris ejection mechanisms into the rotating crucible structure, allowing both metal flow management and debris control to be achieved through a single integrated system
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 solution stabilizes EUV light intensity, enhances the productivity of semiconductor manufacturing by maintaining laser operating standards, and reduces maintenance needs, leading to increased throughput and cost savings.
Implementation Method 1
EUV lithography employs a laser-produced plasma (LPP), which emits EUV light. The LPP is produced by focusing a high-power laser beam, from a carbon dioxide (CO2) laser and the like, onto a metal target, such as tin (Sn), in order to transition it into a highly ionized plasma state.
Implementation Method 2
A rotating crucible with strategically placed bumps and an eave is used to manage the flow of metal debris, converting turbulent flow to laminar flow and directing debris to a catcher
Data Source
AI summary
To improve EUV emission stability, bumps and eaves are added to the interior wall of a rotating crucible that produces EUV light by vaporizing a pre-heated metal, such as tin, using a laser. The bumps and eaves prevent migration of debris and control liquid metal flow, which is otherwise distributed over time by the centrifugal forces generated as the crucible rotates. The bumps and eaves stabilize EUV emissions by changing turbulent liquid metal flow to a predominately laminar flow. Tin catchers of various designs are available to collect and recycle a significant portion of the debris and unused liquid metal. A closed crucible chamber design alleviates non-uniform heating issues.