EUV Light Generation System Pulse Timing Control
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Solution Overview
Problem
Current extreme ultraviolet light generation systems for semiconductor manufacturing face challenges in generating ions with high ion energy, which can degrade the multi-layer reflective films used in EUV condensation mirrors, leading to reduced reflectance and efficiency in EUV light production.
Innovation Solution
The system employs a laser system that outputs a sequence of pre-pulse and main pulse laser beams with specific fluence and delay time relationships to control the ion energy generated during the EUV light production process, including the use of regenerative amplifiers and optical shutters to manage pulse energy and timing, thereby reducing high ion energy generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high-energy pulse laser beam is used to generate EUV light, then EUV light generation efficiency is improved, but ion energy increases causing film degradation
Solution Approach 1:
The single high-energy pulse is segmented into multiple pulses with different energy levels (first pre-pulse, second pre-pulse, and main pulse). Each pulse serves a specific function: the first pre-pulse creates initial plasma, the second pre-pulse enhances ionization, and the main pulse generates EUV light. This segmentation allows control of ion energy while maintaining EUV generation efficiency.
Solution Approach 2:
The first and second pre-pulses are applied before the main pulse to prepare the target material. The first pre-pulse creates initial plasma and modifies the target surface, while the second pre-pulse further enhances ionization conditions. This preliminary action reduces the ion energy generated by the subsequent main pulse while maintaining EUV generation capability.
2Illumination intensity
If pulse energy is increased to maintain EUV output, then EUV light intensity is improved, but multi-layer reflective film degradation accelerates
Solution Approach 1:
Instead of using a single high-energy pulse, the system employs periodic action with multiple pulses at controlled energy levels. The first pre-pulse, second pre-pulse, and main pulse are delivered in sequence with specific timing intervals. This periodic approach maintains EUV light intensity while distributing the energy load, preventing excessive ion energy that would degrade the multi-layer reflective film.
3Device complexity
If single pulse irradiation is used to simplify the process, then device complexity is reduced, but ion energy control precision deteriorates
Solution Approach 1:
The laser system dynamically adjusts the energy distribution across multiple pulses rather than using a static single-pulse approach. The first pre-pulse, second pre-pulse, and main pulse each have optimized energy levels and timing intervals that can be adjusted based on process requirements. This dynamic control enables precise ion energy management while maintaining manageable device complexity through standardized laser components.
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 effectively reduces ion energy to prevent film degradation, maintaining reflectance and enhancing EUV light generation efficiency by optimizing the pulse energy and timing of the laser beams.
Implementation Method 1
a laser produced plasma (LPP) device that uses plasma generated by irradiating a target material with a pulse laser beam
Data Source
AI summary
An extreme ultraviolet light generation system includes: a chamber; a target generation unit; a laser system configured to output a first pre-pulse laser beam, a second pre-pulse laser beam, and a main pulse laser beam so that fluence of the first pre-pulse laser beam is 1.5 J/cm2 to 16 J/cm2 inclusive at a position where a target is irradiated with the first pre-pulse laser beam; and a control unit configured to control the laser system so that a first delay time from a timing of irradiation of the target with the first pre-pulse laser beam to a timing of irradiation with the second pre-pulse laser beam and a second delay time from the timing of irradiation of the target with the second pre-pulse laser beam to a timing of irradiation with the main pulse laser beam have a following relation:the first delay time<the second delay time.