EUV Light Generation System Multi-Pulse Laser Target Irradiation
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Solution Overview
Problem
Current extreme ultraviolet (EUV) light generation systems for semiconductor microfabrication face challenges in achieving high conversion efficiency from pulse laser energy to EUV light, particularly at the 32 nm or less node, where the existing systems struggle to optimize the fluence and timing of pre-pulse and main pulse laser beams to efficiently produce EUV light.
Innovation Solution
The system employs a configuration where a target is irradiated with a first pre-pulse laser beam, followed by a second pre-pulse laser beam, and then a main pulse laser beam, with controlled fluence and waveform to break down the target into fine particles, steam, and pre-plasma, optimizing the conversion to EUV light through precise control of beam diameters, wavelengths, and timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single main pulse laser beam is used to generate EUV light, then the system structure is simple, but the conversion efficiency from laser energy to EUV light is insufficient
Solution Approach 1:
The laser system is segmented into multiple independent laser beams (first pre-pulse laser beam, second pre-pulse laser beam, and main pulse laser beam) that sequentially irradiate the target. Each beam performs a specific function: the first pre-pulse creates initial plasma, the second pre-pulse enhances plasma density, and the main pulse generates EUV light. This segmentation allows optimization of each beam's parameters independently, significantly improving overall conversion efficiency while maintaining manageable system complexity.
Solution Approach 2:
The pre-pulse laser beams perform preliminary actions on the target before the main pulse arrives. The first pre-pulse laser beam pre-ionizes the target surface to create a plasma precursor, and the second pre-pulse laser beam further densifies this plasma. These preliminary actions prepare the target in an optimal state for EUV generation, allowing the main pulse to convert energy much more efficiently than irradiating a cold target directly.
2Productivity
If the fluence of pre-pulse laser beams is increased to improve plasma generation, then EUV light output increases, but the target damage and energy waste increase
Solution Approach 1:
Each laser beam is assigned a specific fluence range optimized for its function: the first pre-pulse uses lower fluence (0.1-1.0 J/cm²) for gentle pre-ionization, the second pre-pulse uses moderate fluence (1.0-5.0 J/cm²) for plasma densification, and the main pulse uses high fluence (5.0-20.0 J/cm²) for EUV generation. This localized optimization of fluence for each beam's specific purpose maximizes EUV output while minimizing unnecessary target damage and energy waste that would occur with uniform high fluence application.
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 configuration significantly enhances the conversion efficiency of laser energy to EUV light, improving the performance of EUV light generation systems for advanced semiconductor processes by optimizing the interaction of laser beams with the target.
Implementation Method 1
a laser system configured to generate a first pre-pulse laser beam, a second pre-pulse laser beam, and a main pulse laser beam so that the target is irradiated with the first pre-pulse laser beam, the second pre-pulse laser beam, and the main pulse laser beam in this order
Implementation Method 2
the target is irradiated with the first pre-pulse laser beam, the second pre-pulse laser beam, and the main pulse laser beam in this order
Implementation Method 3
a target generation unit configured to output a target toward a plasma generation region in the chamber
Implementation Method 4
This configuration significantly enhances the conversion efficiency of laser energy to EUV light
Data Source
AI summary
An extreme ultraviolet light (EUV) generation system is configured to improve conversion efficiency of energy of a laser system to EUV energy by improving the efficiency of plasma generation. The EUV generation system includes a target generation unit configured to output a target toward a plasma generation region in a chamber. The laser system is configured to generate a first pre-pulse laser beam, a second pre-pulse laser beam, and a main pulse laser beam so that the target is irradiated with the first pre-pulse laser beam, the second pre-pulse laser beam, and the main pulse laser beam in this order. In addition, the EUV generation system includes a controller configured to control the laser system so that a fluence of the second pre-pulse laser beam is equal to or higher than 1 J/cm2 and equal to or lower than a fluence of the main pulse laser beam.