Easy-handling minimum mass laser target scaffold based on sub-millimeter air bubble -An example of laser plasma extreme ultraviolet generation-

Abstract

Low density materials can control plasma properties of laser absorption, which can enhance quantum beam generation. The recent practical extreme ultraviolet light (EUV) is the first industrial example of laser plasma source with low density targets. Here we propose an easy-handling target source based on a hollow sub-millimeter microcapsule fabricated from polyelectrolyte cationic and anionic surfactant on air bubbles. The lightweight microcapsules acted as a scaffold for surface coating by tin (IV) oxide nanoparticles (22-48%), and then dried. As a proof of concept study, the microcapsules were ablated with a Nd:YAG laser (7.1 × 10 10 W/cm 2 , 1 ns) to generate 13.5 nm EUV relatively directed to laser incidence. The laser conversion efficiency (CE) at 13.5 nm 2% bandwidth from the tin-coated microcapsule (0.8%) was competitive compared with bulk tin (1%). We propose that microcapsule aggregates could be utilized as a potential small scale/compact EUV source, and future quantum beam sources by changing the coating to other elements.

A laser-produced plasma source based on thin-film Gd targets for next-generation extreme ultraviolet lithography

“…With respect to the second approach, a mass-limited target is preferred as it can not only produce sufficient EUV emission but also reduce the neutral atoms and low-ionized ions that come from the deep layer of the target [17]. There are several forms of mass-limited targets, such as sphere targets made by depositing materials on balls [18][19][20][21] or bubbles [22], thin-film targets coated on planar Si wafers or glass [23,24] and uniform liquid droplets [25,26]. Comparably, the thin-film target approach is simpler, and it can be easily applied to the study of the properties of mass-limited targets made of new materials in the laboratory.…”

Dynamics of laser produced plasma from foam targets for future nanolithography devices and X-ray sources

“…In the field of semiconductor lithography, liquid tin droplets irradiated by a double pulse laser scheme is currently adopted to enhance the EUV emission intensity with 100 kHz repetition 24 , 25 . However, the double pulse scheme has a durability problem due to the difficulty of controlling the droplet expansion dynamics and fragmentation caused by the pre-pulse 22 , 26 . Currently, some research related to the laser produced low-density tin plasma show that the complex double pulse laser scheme is expected to be replaced by using low-density foam targets in the future 26 – 28 .…”

“…However, the double pulse scheme has a durability problem due to the difficulty of controlling the droplet expansion dynamics and fragmentation caused by the pre-pulse 22 , 26 . Currently, some research related to the laser produced low-density tin plasma show that the complex double pulse laser scheme is expected to be replaced by using low-density foam targets in the future 26 – 28 . In addition, low density foam targets have been demonstrated to have higher X-ray radiation than solid targets in reports of the laser produced Au 23 , 29 , 30 , Cu 31 , V 31 , Ti 32 , Ca 33 , Bi 34 , and cellulose triacetate 20 plasma.…”

Dynamics of Laser Produced Plasma From Foam Targets for Future Nanolithography Devices and X-Ray Sources

“…In the field of semiconductor lithography, liquid tin droplets irradiated by a double pulse laser scheme is currently adopted to enhance the EUV emission intensity with 100 kHz repetition 24,25 . However, the double pulse scheme has a durability problem due to the difficulty of controlling the droplet expansion dynamics and fragmentation caused by the pre-pulse 22,26 . Currently, some research related to the laser produced low-density tin plasma show that the complex double pulse laser scheme is expected to be replaced by using low-density foam targets in the future [26][27][28] .…”

“…However, the double pulse scheme has a durability problem due to the difficulty of controlling the droplet expansion dynamics and fragmentation caused by the pre-pulse 22,26 . Currently, some research related to the laser produced low-density tin plasma show that the complex double pulse laser scheme is expected to be replaced by using low-density foam targets in the future [26][27][28] . In addition, low density foam targets have been demonstrated to have higher x-ray radiation than solid targets in reports of the laser produced Au 23,29,30 , Cu 31 , V 31 , Ti 32 , Ca 33 , Bi 34 , and cellulose triacetate 20 plasma.…”