An EUV light source is disclosed that may include a laser source, eg CO2 laser, a plasma chamber, and a beam delivery system for passing a laser beam from the laser source into the plasma chamber Embodiments are disclosed which may include one or more of the following; a bypass line may be provided to establish fluid communication between the plasma chamber and the auxiliary chamber, a focusing optic, eg mirror, for focusing the laser beam to a focal spot in the plasma chamber, a steering optic for steering the laser beam focal spot in the plasma chamber, and an optical arrangement for adjusting focal power

Laser produced plasma euv light source

The source is an integral part of an extreme ultraviolet lithography (EUVL) tool. Such a source, as well as the EUVL tool, has to fulfil very high demands both technical and cost oriented. The EUVL tool operates at a wavelength of 13.5 nm, which requires the following new developments. The light production mechanism changes from conventional lamps and lasers to relatively high-temperature emitting plasmas. The light transport, mainly refractive for deep ultraviolet (DUV), should be reflective for EUV. The source specifications as derived from the customer requirements on wafer throughput mean that the output EUV source power has to be hundreds of watts. This in its turn means that tens to hundreds of kilowatts of dissipated power has to be managed in a relatively small volume. In order to keep lithography costs as low as possible, the lifetime of the components should be as long as possible and at least of the order of thousands of hours. This poses a challenge for the sources, namely how to design and manufacture components robust enough to withstand the intense environment of high heat dissipation, flows of several keV ions as well as the atomic and particular debris within the source vessel. As with all lithography tools, the imaging requirements demand a narrow illumination bandwidth. Absorption of materials at EUV wavelengths is extreme with extinguishing lengths of the order of tens of nanometres, so the balance between high transmission and spectral purity requires careful engineering. All together, EUV lithography sources present technological challenges in various fields of physics such as plasma, optics and material science.These challenges are being tackled by the source manufacturers and investigated extensively in the research facilities around the world.An overview of the published results on the topic as well as the analyses of the physical processes behind the proposed solutions will be presented in this paper.

https://iopscience.iop.org/article/10.1088/0022-3727/44/25/253001/pdf

Physical processes in EUV sources for microlithography

Offset in the ejection direction of target material droplets is corrected in order to stabilize EUV output in an EUV light source device. An extreme ultraviolet light source device includes a droplet generation device 110 that outputs target material droplets 101 towards a predetermined plasma emission point 103; a charging device 130 that charges the target material droplets 101; a trajectory correction device 140 that generates a force field in the trajectory to correct the travel direction of the charged target material droplets 101 a so that the charged target material droplets 101 a travel towards the plasma emission point 103; and a laser light source 150 that irradiates, at the plasma emission point 103, a laser beam onto the charged target material to generate plasma thereby.

Extreme ultraviolet light source device

A review is presented for the research development of Stirling cycle engines for recovering low and moderate temperature heat. The Stirling cycle engines are categorized into four types, including kinetic, thermoacoustic, free-piston, and liquid piston types. The working characteristics, features, technological details, and performances of the related Stirling cycle engines are summarized. Upon comparing the available experimental results and the technology potentials, the research directions and the possible applications of different Stirling cycle engines are further discussed and identified. It is concluded that kinetic Stirling engines and thermoacoustic engines have the greatest application prospect in low and moderate temperature heat recoveries in terms of output power scale, conversion efficiency, and costs. In particular, kinetic Stirling engines should be oriented toward two directions for practical applications, including providing low-cost solutions for low temperatures, and moderate efficient solutions with moderate costs for medium temperatures. Thermoacoustic engines for low temperature applications are especially attractive due to their low costs, high efficiencies, superior reliabilities, and simplicities over the other mechanical Stirling engines. This work indicates that a cost effective Stirling cycle engine is practical for recovering small-scale distributed low-grade thermal energy from various sources.

/pdf/stirling-cycle-engines-for-recovering-low-and-moderate-4i8vuhf5zt.pdf

Stirling cycle engines for recovering low and moderate temperature heat: A review

Apparatuses and processes for maskless deposition of electronic and biological materials. The process is capable of direct deposition of features with linewidths varying from the micron range up to a fraction of a millimeter, and may be used to deposit features on substrates with damage thresholds near 100° C. Deposition and subsequent processing may be carried out under ambient conditions, eliminating the need for a vacuum atmosphere. The process may also be performed in an inert gas environment. Deposition of and subsequent laser post processing produces linewidths as low as 1 micron, with sub-micron edge definition. The apparatus nozzle has a large working distance—the orifice to substrate distance may be several millimeters—and direct write onto non-planar surfaces is possible.

Apparatuses and methods for maskless mesoscale material deposition

Traveling-wave thermoacoustic heat engines have been demonstrated to convert high-temperature heat to acoustic power with high efficiency without using moving parts Electrodynamic linear alternators and compressors have demonstrated high acoustic-to-electric transduction efficiency as well as long maintenance-free lifetimes By optimizing a small-scale traveling-wave thermoacoustic engine for use with an electrodynamic linear alternator, we have created a traveling-wave thermoacoustic electric generator; a power conversion system suitable for demanding applications such as electricity generation aboard spacecraft

Traveling-wave thermoacoustic electric generator

A target material delivery system in the form of a nozzle (50) for an EUV radiation source (10). The nozzle (50) includes a target material supply line (66) having an orifice (68) through which droplets (76) of a liquid target material (64) are emitted, where the droplets (76) have a predetermined size, speed and spacing therebetween. The droplets (76) are mixed with a carrier gas (74) in a mixing chamber (54) enclosing the target material chamber (66) and the mixture of the droplets (76) and the carrier gas (74) enter a drift tube (56) from the mixing chamber (54). The droplets (76) are emitted into an accelerator chamber (124) from the drift tube (56) where the speed of the droplets (76) is increased to control the spacing therebetween. A vapor extractor (90) can be mounted to the accelerator chamber (124) or the drift tube (56) to remove the carrier gas (74) and target material vapor, which would otherwise adversely affect the EUV radiation generation.

/pdf/gasdynamically-controlled-droplets-as-the-target-in-a-laser-1tjj8a70b7.pdf

Gasdynamically-controlled droplets as the target in a laser-plasma extreme ultraviolet light source

Laser-produced plasmas (LPPs) are being developed as light sources for EUV lithography. To meet the requirements for high-volume manufacturing, LPP EUV sources must generate intense EUV output in the 13.5 nm band, and minimize source-induced degradation of EUV optics allowing hundreds of hours of clean operation. Xenon has been identified as a promising target material for LPP EUV light sources, with the potential for both high-efficiency EUV generation, and low optics contamination. Several dense xenon target configurations have been tested including aerosol sprays, continuous liquid streams, condensed xenon droplets, and frozen solid xenon. Important LPP performance characteristics, such as conversion efficiency, EUV radiation distribution, EUV optics degradation by material erosion and/or deposition, and the physical interface to the EUV optical system, are strongly influenced by the xenon target design. The performance of xenon targets with measured conversion efficiencies in the 0.4 percent to 1.4 percent range is reported. Prospects for xenon targets to reach the EUV power generation and contamination goals for production lithography tools are addressed.

Xenon target performance characteristics for laser-produced plasma EUV sources

A nozzle ( 46 ) for a laser-plasma EUV radiation source that provides thermal isolation between the nozzle body ( 48 ) and the target material flowing therethrough. A target delivery tube ( 72 ) is provided that extends through the nozzle body ( 48 ). The delivery tube ( 72 ) has an expansion aperture ( 80 ) positioned behind an exit collimator ( 50 ) of the nozzle body ( 48 ). The delivery tube ( 72 ) is made of a low thermal conductivity material, such as stainless steel, and is in limited contact with the nozzle body ( 48 ) so that heating of the nozzle body ( 48 ) from the plasma does not heat the liquid target material being delivered through the delivery tube ( 72 ). The expansion aperture ( 80 ) has a smaller diameter than the exit collimator ( 50 ).

/pdf/high-temperature-euv-source-nozzle-30h5795ekg.pdf

High temperature EUV source nozzle

A laser-plasma EUV radiation source (50) that generates larger liquid droplets (72) for the plasma target material. The EUV source (50) forces a liquid (58), preferably Xenon, through a nozzle (64), instead of forcing a gas through the nozzle. The geometry of the nozzle (64) and the pressure of the liquid (58) through the nozzle (54) atomizes the liquid (58) to form a dense spray (70) of droplets (72). Because the droplets (72) are formed from a liquid, they are larger in size, and are more conducive to generating EUV radiation. A condenser (60) is used to convert gaseous Xenon (54) to the liquid (58) prior to being forced through the nozzle (64).

Michael B. Petach

Papers

Traveling-wave thermoacoustic electric generator

Gasdynamically-controlled droplets as the target in a laser-plasma extreme ultraviolet light source

Xenon target performance characteristics for laser-produced plasma EUV sources

High temperature EUV source nozzle

Liquid sprays as the target for a laser-plasma extreme ultraviolet light source