antiterror13
Brigadier
Would Xenon based be easier and cheaper to implement than Tin (even lower efficacy) ?
Chinese semiconductor thread II
- Thread starter vincent
- Start date
It’s probably going to be a lot less complicated for debris management but it will require a far more powerful feed laser to get equivalent light output, and laser power is the primary technical constraint for LPP systems.
Another ultra precision optics machining tool maker from Chengdu. Supplier of satellite camera with worlds highest resolution and world’s largest aperture ion beam ultra precision machining center with subnanometer capability. My guess for usage scenarios: telescopes and high/hyper NA euv mirrors
However, the latest NAND chips produced by Yangtze Memory using domestic equipment have made corresponding compromises in the number of stacking layers, which is about 70 layers less than earlier products, and the output is lower.
In response to this, Yangtze Memory said that the company is constantly optimizing product performance, and changes in the number of layers have nothing to do with equipment output. As the manufacturing process, process and experience continue to mature, the number of stacked layers will continue to increase.
In response to this, Yangtze Memory said that the company is constantly optimizing product performance, and changes in the number of layers have nothing to do with equipment output. As the manufacturing process, process and experience continue to mature, the number of stacked layers will continue to increase.
The laser mentioned in this article reached 150 kw, not 60 kw, actually. The laser technology being discussed is a multi-channel YAG fiber laser. By 2018 they got to 40 kw with 32 combined fiber channels, but they’ve pushed this laser technology to 150 kw with 60 channels.
However, comparing this YAG laser with ASML’s 40 kw CO2 laser is not so straightforward. The fiber lasers being discussed in this article are of a different wavelength from the CO2 lasers currently being used by ASML, (1 um for the YAG fiber laser and 10 um for the CO2 laser) so they have different excitation dynamics with tin plasma. The 1 um wavelength is more fully absorbed by tin plasma so they cause more plasma excitation but the reaction is so energetic you also get lots of second order reabsorption of initial excited emissions which then broadens the emission spectra and can lower conversion efficiency for the target wavelength (13.5 nm). The 10 um wavelength is absorbed less efficiently by tin plasma but the emissions spectra are much more narrow and thus well targeted for 13.5 nm. This means there are extra challenges for the fiber laser over the CO2 laser in terms of conversion efficiency and spectral purity (if the emissions spectra is broad you have to filter out a lot of the photons you generate and thus have worse yield for the energy put in to the plasma excitation process).
The paper I’ve linked below discusses the physics and technical considerations for these different lasers and their applications in LPP EUV light sources. Interestingly enough, this paper also discusses the possibility for longer wavelength fiber lasers in between 1 um and 10 um which can split some of the difference in plasma excitation dynamics, and specifically mentions thulium doped fiber lasers at the 1.8-2.5 um wavelength range as one path fiber lasers for LPP EUV could take, which the Zhihu article also mentions as the next step being worked on for China’s multichannel fiber laser. Whether this is the technology going into China’s first commercial EUV prototype or a separate branch of R&D for future iterations isn’t clear though. My blind guess is they might have just gone with the 150 kw YAG laser and dealt with some of the downstream issues it might have with conversion efficiency and spectral purity for now.
EDIT: I decided to peruse a bit more science lit on thulium lasers for LPP EUV and stumbled onto , which I believed was shared in this thread a year ago. Back then the takeaway was that researchers in China had shown the ability to reach 6.9% conversion efficiency for tin plasma EUV in simulations. But in retrospect, what we seemed to have missed was that they were simulating tin plasma excitation for a 2 um drive laser, which would strongly imply that this is tied to the work being done on thulium lasers.
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Tomshardware is supposed to be a reliable source but they got it wrong this time
he Institute of Microelectronics has made new progress in 795nm narrow linewidth VCSEL
Vertical cavity surface emitting lasers (VCSELs) have the advantages of small size, low threshold current, stable wavelength with temperature, circular beam and high reliability, and are the core light sources of atomic clocks, atomic magnetometers, atomic gyroscopes , etc. However, the spectral linewidth of traditional VCSELs is relatively wide, generally 50-100 MHz, which cannot match the natural atomic linewidth (5 MHz for cesium), limiting the further improvement of the performance of atomic sensing systems.
Recently, the team of Academician Wu Dexin from the Institute of Microelectronics proposed a new type of longitudinal multi-cavity coupled VCSEL. Compared with traditional VCSELs, the new multi-cavity coupled VCSEL has a longer effective cavity length and photon lifetime. Its resonant cavity consists of an active cavity and two passive cavities. When a photon enters the passive resonant cavity, a rapid phase shift will occur, and it will eventually be transmitted out after multiple cycles in the cavity, greatly increasing the photon lifetime and thus compressing the spectral linewidth. Since the higher-order mode has higher diffraction loss in the extended cavity than the fundamental mode, it can still support single-mode lasing and increase the single-mode output power even at larger currents and oxidation apertures. The 795nm VCSEL achieves high performance such as a spectral linewidth of 7.3MHz, a single-mode power of 4.6mW (at 25°C), and a polarization suppression ratio of 27dB, and can play an important role in the next generation of atomic sensing systems.
This work was supported by Beijing Science and Technology Star Program and the National Natural Science Foundation of China. The research results were published in the top journal in the field of optical communications, Journal of Lightwave Technology, with the title of " Longitudinal Multi-Cavity Coupled VCSELs With Narrow Linewidth and High Single Mode Power for Quantum Sensing ". Xun Meng, a young researcher from the Institute of Microelectronics, is the first author of the paper, and Pan Guanzhong, a young researcher, is the corresponding author.
Recently, the team of Academician Wu Dexin from the Institute of Microelectronics proposed a new type of longitudinal multi-cavity coupled VCSEL. Compared with traditional VCSELs, the new multi-cavity coupled VCSEL has a longer effective cavity length and photon lifetime. Its resonant cavity consists of an active cavity and two passive cavities. When a photon enters the passive resonant cavity, a rapid phase shift will occur, and it will eventually be transmitted out after multiple cycles in the cavity, greatly increasing the photon lifetime and thus compressing the spectral linewidth. Since the higher-order mode has higher diffraction loss in the extended cavity than the fundamental mode, it can still support single-mode lasing and increase the single-mode output power even at larger currents and oxidation apertures. The 795nm VCSEL achieves high performance such as a spectral linewidth of 7.3MHz, a single-mode power of 4.6mW (at 25°C), and a polarization suppression ratio of 27dB, and can play an important role in the next generation of atomic sensing systems.
This work was supported by Beijing Science and Technology Star Program and the National Natural Science Foundation of China. The research results were published in the top journal in the field of optical communications, Journal of Lightwave Technology, with the title of " Longitudinal Multi-Cavity Coupled VCSELs With Narrow Linewidth and High Single Mode Power for Quantum Sensing ". Xun Meng, a young researcher from the Institute of Microelectronics, is the first author of the paper, and Pan Guanzhong, a young researcher, is the corresponding author.