Semiconductor Processing Tool with Multi-Pulse EUV Laser Heating
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Solution Overview
Problem
Existing EUV radiation sources face inefficiencies due to non-uniform laser beam profiles, leading to uneven energy distribution, low collimation, high divergence, and thermal effects, which affect plasma generation, debris formation, and overall system performance.
Innovation Solution
A laser source employing a multi-pulse technique generates pre-pulse and main-pulse laser beams, augmented by an auxiliary laser beam, to correct and compensate for non-uniform energy distribution, improving plasma heating efficiency and reducing thermal effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single laser beam is used to irradiate Sn droplets, then the device complexity is low, but the energy distribution is non-uniform and collimation is poor
Solution Approach 1:
The single laser beam is segmented into multiple pulses (pre-pulse and main-pulse) with different characteristics. The pre-pulse has lower intensity to avoid excessive heating, while the main-pulse has higher intensity for efficient plasma generation. This temporal segmentation resolves the contradiction by allowing optimized energy distribution without increasing spatial complexity.
Solution Approach 2:
The laser irradiation is applied periodically in the form of multiple pulses rather than a single continuous beam. This periodic action enables better control over energy deposition timing, improving collimation and reducing thermal effects while maintaining manageable system complexity through pulsed operation.
2Power
If higher laser intensity is used to increase EUV radiation output, then the conversion efficiency improves, but thermal effects increase and plasma generation becomes uneven
Solution Approach 1:
The high-intensity laser energy is segmented into multiple pulses applied at different times. The pre-pulse gently heats the droplet surface, while the main-pulse delivers the high intensity needed for plasma generation. This prevents excessive thermal accumulation and creates more uniform plasma, resolving the contradiction between power output and thermal management.
Solution Approach 2:
A pre-pulse is applied before the main high-intensity pulse to preliminarily heat and prepare the Sn droplet. This preliminary action reduces the thermal shock and creates more uniform plasma when the main pulse arrives, allowing higher EUV output with reduced thermal effects.
3Productivity
If a multi-pulse laser technique is used to improve energy distribution, then plasma heating efficiency increases, but the device complexity increases
Solution Approach 1:
The laser system is segmented into two functional pulses (pre-pulse and main-pulse) rather than requiring complex multi-component systems. This segmentation achieves improved plasma heating efficiency through simple temporal separation of pulse functions, avoiding excessive device complexity.
Solution Approach 2:
The laser parameters (intensity, duration, timing) are changed between pulses to optimize performance. The pre-pulse uses lower intensity with longer duration for gentle heating, while the main-pulse uses higher intensity for efficient plasma generation. These parameter changes improve productivity without requiring complex device architecture.
4Ease of operation
If conventional laser beams are used, then the system is simple to operate, but beam divergence is high and collimation is poor
Solution Approach 1:
The periodic pulsed operation of the laser enables better beam control and collimation. The time-separated pulses allow for optimized optical path management and reduce thermal lensing effects that cause divergence, maintaining ease of operation while improving beam shape through pulsed rather than continuous operation.
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 enhances the intensity and uniformity of laser beams, increasing the conversion efficiency of EUV radiation generation and improving the throughput and yield of semiconductor devices.
Implementation Method 1
A carbon dioxide (CO2)-based laser source is an example laser source that can provide high power and energy
Implementation Method 2
The laser source generates a pre-pulse laser beam and main-pulse laser beam to achieve greater heating efficiency in tin (Sn)-based plasma
Implementation Method 3
The Sn droplets are generated by a droplet generator (DG) head, which provides the Sn droplets into a scanner chamber
Implementation Method 4
The laser source generates a pre-pulse laser beam and main-pulse laser beam to achieve greater heating efficiency in tin (Sn)-based plasma to increase conversion efficiency
Implementation Method 5
The EUV radiation is produced from a laser produced plasma (LPP) that is generated by exposing droplets of tin (Sn) to a carbon dioxide (CO2)-based laser
Data Source
AI summary
Example implementations described herein include a laser source and associated methods of operation that can balance or reduce uneven beam profile problem and even improve plasma heating efficiency to enhance conversion efficiency and intensity for extreme ultraviolet radiation generation. The laser source described herein generates an auxiliary laser beam to augment a pre-pulse laser beam and/or a main-pulse laser beam, such that uneven beam profiles may be corrected and/or compensated. This may improve an intensity of the laser source and also improve an energy distribution from the laser source to a droplet of a target material, effective to increase an overall operating efficiency of the laser source.