EUV Source Droplet Control via Waveform-Driven Nozzle Pressure
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Solution Overview
Problem
Limited control over droplet formation in EUV systems leads to unstable EUV generation, affecting the accuracy of lithographic processes.
Innovation Solution
A system comprising a nozzle, an electromechanical element, and a waveform generator is used to control the pressure applied to the nozzle, generating coalesced droplets through a combination of periodic waveforms with specific frequency ratios, thereby stabilizing EUV generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If source material is delivered as droplets through a nozzle in EUV systems, then EUV radiation can be generated, but limited control over droplet formation causes unstable EUV generation
Solution Approach 1:
The patent applies periodic action by using a waveform generator to apply periodic pressure variations to the nozzle at specific frequencies. This periodic pressure modulation controls the droplet ejection process, ensuring consistent droplet formation and improving the stability of EUV radiation generation by synchronizing the droplet release with the pressure cycle.
Solution Approach 2:
The patent implements parameter changes by varying the pressure parameters applied to the nozzle through the waveform generator. By adjusting pressure amplitude, frequency, and timing parameters, the system achieves precise control over droplet formation, size, and ejection rate, thereby improving both the stability of EUV generation and the precision of droplet characteristics.
2Manufacturing precision
If pressure is applied to the nozzle to control droplet ejection, then droplet formation can be controlled, but the system complexity increases
Solution Approach 1:
The patent applies mechanics substitution by replacing complex mechanical droplet formation control mechanisms with an electromechanical system. Instead of using complex mechanical valves or regulators, the system uses a waveform generator to apply electrical signals that control an electromechanical element (such as a piezoelectric actuator) to regulate nozzle pressure, thereby achieving precise droplet control with simpler overall system architecture.
Solution Approach 2:
The patent implements self-service by using the waveform generator to automatically control the pressure applied to the nozzle based on programmed parameters. The system self-regulates droplet ejection characteristics without requiring external manual adjustment or complex feedback mechanisms, simplifying operation and reducing system complexity while maintaining precise control.
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
The solution improves the control over the breakup and coalescence process, reducing instabilities in EUV generation and enhancing the accuracy of lithographic processes.
Implementation Method 1
The waveform generator is electrically coupled to the electromechanical element and is configured to generate an electrical signal to control the applied pressure on the first nozzle. The electrical signal comprises a first periodic waveform having a first frequency and a second periodic waveform having a second frequency different from the first frequency.
Implementation Method 2
The system is configured to generate coalesced droplets from a coalescing of the initial droplets based on the first and second periodic waveforms and drag.
Implementation Method 3
One technique for generating droplets involves melting a target material such as tin and then forcing it under high pressure through a relatively small diameter orifice, such as an orifice having a diameter of about 0.5 μm to about 30 pm, to produce a stream of droplets. Under most conditions, in a process called Rayleigh breakup, naturally occurring instabilities, e.g. noise, in the stream exiting the orifice, will cause the stream to break up into droplets.
Data Source
AI summary
A method includes ejecting initial droplets of a material using a nozzle. The method includes applying a pressure on the nozzle using an electromechanical element. The method includes controlling the applied pressure on the nozzle using an electrical signal generated by a waveform generator. The electrical signal includes a first periodic waveform and a second periodic waveform. The method includes coalescing the initial droplets to generate coalesced droplets based on the first and second periodic waveforms and drag. The method includes generating a detection signal, using a detector, corresponding to time intervals between crossings of coalesced droplets at the detector. The method includes determining at least first and second ones of the time intervals using a processor.