EUV Radiation Source With Simultaneous Multi-Droplet Irradiation
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Solution Overview
Problem
Existing laser-produced plasma (LPP) EUV sources face inefficiencies in generating extreme ultraviolet radiation due to the limited energy transfer to droplets, which hinders the resolution improvements needed for further miniaturization in semiconductor manufacturing.
Innovation Solution
The EUV radiation source employs a mechanism where a high-power laser beam is divided into multiple portions, creating parallel fringes that interact with smaller droplets, increasing the surface area and interaction time, thereby enhancing energy transfer and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high-power laser beam is focused on a single droplet target, then the energy concentration is high, but the surface area for energy transfer is limited, reducing overall efficiency
Solution Approach 1:
The single droplet target is segmented into multiple smaller droplet targets arranged in an array. The laser beam is correspondingly divided into multiple portions that simultaneously irradiate each droplet. This segmentation increases the total surface area for energy transfer while maintaining high energy concentration at each droplet, thereby resolving the contradiction between energy concentration and surface area.
2Area of moving object
If the laser beam interacts with smaller droplets, then the surface area increases, but the interaction time decreases, potentially reducing energy transfer efficiency
Solution Approach 1:
Multiple droplets are arranged in a sequence along the laser beam path, creating a continuous train of plasma emissions. As each droplet passes through the laser focus zone, it generates EUV radiation, and the next droplet immediately follows. This continuous sequence maintains sustained useful action, compensating for the reduced interaction time with individual smaller droplets.
3Productivity
If multiple droplets are irradiated simultaneously, then the total EUV radiation output increases, but the system complexity increases
Solution Approach 1:
The droplet array system is designed to be self-aligning, where the droplets naturally position themselves in the laser focus zone through controlled ejection and motion. The system uses the inherent properties of droplet formation and laser focusing to achieve automatic synchronization, reducing the need for complex external control mechanisms while maintaining high EUV radiation output from multiple droplets.
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 increases the efficiency of EUV radiation production by optimizing energy transfer to smaller droplets, leading to improved resolution in EUV lithography systems.
Implementation Method 1
a high-power laser beam is focused on small droplet targets of metal, such as tin, to form a highly ionized plasma that emits EUV radiation
Implementation Method 2
The optical system is configured to divide the laser beam into two or more portions and to pass the two or more portions through two or more slits to generate two or more fringes
Data Source
AI summary
A method for generating an extreme ultraviolet (EUV) radiation includes simultaneously irradiating two or more target droplets with laser light in an EUV radiation source apparatus to produce EUV radiation and collecting and directing the EUV radiation produced from the two or more target droplet by an imaging mirror.