In this review,we describe our research on the development of the 13.5 nm coherent microscope using high-order harmonics for the mask inspection of extreme ultraviolet(EUV)lithography.EUV lithography is a game-changin...In this review,we describe our research on the development of the 13.5 nm coherent microscope using high-order harmonics for the mask inspection of extreme ultraviolet(EUV)lithography.EUV lithography is a game-changing piece of technology for high-volume manufacturing of commercial semiconductors.Many top manufacturers apply EUV technology for fabricating the most critical layers of 7 nm chips.Fabrication and inspection of defect-free masks,however,still remain critical issues in EUV technology.Thus,in our pursuit for a resolution,we have developed the coherent EUV scatterometry microscope(CSM)system with a synchrotron radiation(SR)source to establish the actinic metrology,along with inspection algorithms.The intensity and phase images of patterned EUV masks were reconstructed from diffraction patterns using ptychography algorithms.To expedite the practical application of the CSM,we have also developed a standalone CSM,based on high-order harmonic generation,as an alternative to the SR-CSM.Since the application of a coherent 13.5 nm harmonic enabled the production of a high contrast diffraction pattern,diffraction patterns of sub-100 ns size defects in a 2D periodic pattern mask could be observed.Reconstruction of intensity and phase images from diffraction patterns were also performed for a periodic line-and-space structure,an aperiodic angle edge structure,as well as a cross pattern in an EUV mask.展开更多
Extreme ultraviolet （EUV） spectroscopy has been developed for impurity diagnostics in HL-2A tokamak. The EUV spectrometer consists of an entrance slit, a holographic varied-line- space （VLS） grating, a back-illumi...Extreme ultraviolet （EUV） spectroscopy has been developed for impurity diagnostics in HL-2A tokamak. The EUV spectrometer consists of an entrance slit, a holographic varied-line- space （VLS） grating, a back-illuminated charge-coupled device （CCD） and a laser light source for optical alignment. Spectral lines in wavelength region of 20-500 A observed from HL-2A plasmas were analyzed to study the impurity behavior. Spectral and temporal resolutions used for the analysis were 0.19A at CV （2×33.73 ,h,） and 6 ms, respectively. It was found that carbon, oxygen and iron impurities were usually dominant in the HL-2A plasma. They almost disappeared when the siliconization was carried out. Although the EUV spectra were entirely replaced by the silicon emissions just after the siliconization, the emissions were considerably decreased with accumulation of discharges. Aluminum and neon were externally introduced into the HL-2A plasma based on laser blow-off （LBO） and supersonic molecular beam injection （SMBI） techniques for a trial of the impurity transport study, respectively. The preliminary result is presented for time behavior of EUV spectral lines.展开更多
Extreme ultraviolet(EUV) spectra emitted from low-Z impurity ions in the wavelength range of10–500Å were observed in Experimental Advanced Superconducting Tokamak(EAST)discharges. Several spectral lines from K-a...Extreme ultraviolet(EUV) spectra emitted from low-Z impurity ions in the wavelength range of10–500Å were observed in Experimental Advanced Superconducting Tokamak(EAST)discharges. Several spectral lines from K-and L-shell partially ionized ions were successfully observed with sufficient spectral intensities and resolutions for helium, lithium, boron, carbon,oxygen, neon, silicon and argon using two fast-time-response EUV spectrometers of which the spectral intensities are absolutely calibrated based on the intensity comparison method between visible and EUV bremsstrahlung continua. The wavelength is carefully calibrated using wellknown spectra. The lithium, boron and silicon are individually introduced for the wall coating of the EAST vacuum vessel to suppress mainly the hydrogen and oxygen influxes from the vacuum wall, while the carbon and oxygen intrinsically exist in the plasma. The helium is frequently used as the working gas as well as the deuterium. The neon and argon are also often used for the radiation cooling of edge plasma to reduce the heat flux onto the divertor plate. The measured spectra were analyzed mainly based on the database of National Institute of Standards and Technology. As a result, spectral lines of He Ⅱ, Li Ⅱ–Ⅲ, B Ⅳ–Ⅴ, C Ⅲ–Ⅵ, O Ⅲ–Ⅷ, Ne Ⅱ–Ⅹ,Si Ⅴ–Ⅻ, and Ar Ⅹ–XVI are identified in EAST plasmas of which the central electron temperature and chord-averaged electron density range in Te0=0.6–2.8 keV and ne=(0.5–6.0)×1019 m-3, respectively. The wavelengths and transitions of EUV lines identified here are summarized and listed in a table for each impurity species as the database for EUV spectroscopy using fusion plasmas.展开更多
Interests in the extendibility are growing after the introduction of the LPP (Laser Produced Plasma) EUV source technology in the semiconductor industry, towards higher average power and shorter wavelength, based on t...Interests in the extendibility are growing after the introduction of the LPP (Laser Produced Plasma) EUV source technology in the semiconductor industry, towards higher average power and shorter wavelength, based on the basic architecture of the established LPP EUV source technology. It is discussed in this article that the power scaling of the 13.5nm wavelength source is essentially possible by a slight increase of the driving laser power, CE (Conversion Efficiency) and EUV collection efficiency by some introduction of novel component technologies. Extension of the EUV wavelength towards BEUV (Beyond EUV), namely 6.x nm is discussed based on the general rule of the UTA (Unresolved Transition Arrays) of high Z ions, and development of multilayer mirrors in this particular wavelength region. Technical difficulties are evaluated for the extension of the LPP source technology by considering the narrower mirror bandwidth and higher melting temperature of the candidate plasma materials. Alternative approach based on the superconducting FEL is evaluated in comparison with the LPP source technology for the future solution.展开更多
Particle-In-Cell(PIC)simulations were performed in this work to study the dynamics of the EUVinduced hydrogen plasma.The Monte-Carlo Collision(MCC)model was employed to deal with the collisions between charged particl...Particle-In-Cell(PIC)simulations were performed in this work to study the dynamics of the EUVinduced hydrogen plasma.The Monte-Carlo Collision(MCC)model was employed to deal with the collisions between charged particles and background gas molecules.The dynamic evolution of the plasma sheath,as well as the flux and energy distribution of ions impacting on the mirror surface,was discussed.It was found that the emission of secondary electrons under the EUV irradiation on the ruthenium mirror coating creates a positively charged wall and then prevents the ions from impacting on the mirror and therefore changes the flux and energy distribution of ions reaching the mirror.Furthermore,gas pressure has a notable effect on the plasma sheath and the characteristics of the ions impinging on the mirrors.With greater gas pressure,the sheath potential decreases more rapidly.The flux of ions received by the mirror grows approximately linearly and at the same time the energy corresponding to the peak flux decreases slightly.However,the EUV source intensity barely changes the sheath potential,and its influence on the ion impact is mainly limited to the approximate linear increase in ion flux.展开更多
文摘In this review,we describe our research on the development of the 13.5 nm coherent microscope using high-order harmonics for the mask inspection of extreme ultraviolet(EUV)lithography.EUV lithography is a game-changing piece of technology for high-volume manufacturing of commercial semiconductors.Many top manufacturers apply EUV technology for fabricating the most critical layers of 7 nm chips.Fabrication and inspection of defect-free masks,however,still remain critical issues in EUV technology.Thus,in our pursuit for a resolution,we have developed the coherent EUV scatterometry microscope(CSM)system with a synchrotron radiation(SR)source to establish the actinic metrology,along with inspection algorithms.The intensity and phase images of patterned EUV masks were reconstructed from diffraction patterns using ptychography algorithms.To expedite the practical application of the CSM,we have also developed a standalone CSM,based on high-order harmonic generation,as an alternative to the SR-CSM.Since the application of a coherent 13.5 nm harmonic enabled the production of a high contrast diffraction pattern,diffraction patterns of sub-100 ns size defects in a 2D periodic pattern mask could be observed.Reconstruction of intensity and phase images from diffraction patterns were also performed for a periodic line-and-space structure,an aperiodic angle edge structure,as well as a cross pattern in an EUV mask.
基金supported partially by National Natural Science Foundation of China(Nos.11175061 and 11375057)the JSPS-NRF-NSFC A3Foresight Program in the field of Plasma Physics(NSFC:No.11261140328)
文摘Extreme ultraviolet （EUV） spectroscopy has been developed for impurity diagnostics in HL-2A tokamak. The EUV spectrometer consists of an entrance slit, a holographic varied-line- space （VLS） grating, a back-illuminated charge-coupled device （CCD） and a laser light source for optical alignment. Spectral lines in wavelength region of 20-500 A observed from HL-2A plasmas were analyzed to study the impurity behavior. Spectral and temporal resolutions used for the analysis were 0.19A at CV （2×33.73 ,h,） and 6 ms, respectively. It was found that carbon, oxygen and iron impurities were usually dominant in the HL-2A plasma. They almost disappeared when the siliconization was carried out. Although the EUV spectra were entirely replaced by the silicon emissions just after the siliconization, the emissions were considerably decreased with accumulation of discharges. Aluminum and neon were externally introduced into the HL-2A plasma based on laser blow-off （LBO） and supersonic molecular beam injection （SMBI） techniques for a trial of the impurity transport study, respectively. The preliminary result is presented for time behavior of EUV spectral lines.
基金supported by National Key Research and Development Program of China(Nos.2018YFE0311100,2017YFE0300402,2017YFE0301300)National Natural Science Foundation of China(Nos.Nos.11905146,11775269,U1832126,11805133)+1 种基金Hefei Science Center High-end User Development Fund Project(2019HSCUE014)Chinese Academy of Sciences President’s International Fellowship Initiative(PIFI)(2020VMA0001)。
文摘Extreme ultraviolet(EUV) spectra emitted from low-Z impurity ions in the wavelength range of10–500Å were observed in Experimental Advanced Superconducting Tokamak(EAST)discharges. Several spectral lines from K-and L-shell partially ionized ions were successfully observed with sufficient spectral intensities and resolutions for helium, lithium, boron, carbon,oxygen, neon, silicon and argon using two fast-time-response EUV spectrometers of which the spectral intensities are absolutely calibrated based on the intensity comparison method between visible and EUV bremsstrahlung continua. The wavelength is carefully calibrated using wellknown spectra. The lithium, boron and silicon are individually introduced for the wall coating of the EAST vacuum vessel to suppress mainly the hydrogen and oxygen influxes from the vacuum wall, while the carbon and oxygen intrinsically exist in the plasma. The helium is frequently used as the working gas as well as the deuterium. The neon and argon are also often used for the radiation cooling of edge plasma to reduce the heat flux onto the divertor plate. The measured spectra were analyzed mainly based on the database of National Institute of Standards and Technology. As a result, spectral lines of He Ⅱ, Li Ⅱ–Ⅲ, B Ⅳ–Ⅴ, C Ⅲ–Ⅵ, O Ⅲ–Ⅷ, Ne Ⅱ–Ⅹ,Si Ⅴ–Ⅻ, and Ar Ⅹ–XVI are identified in EAST plasmas of which the central electron temperature and chord-averaged electron density range in Te0=0.6–2.8 keV and ne=(0.5–6.0)×1019 m-3, respectively. The wavelengths and transitions of EUV lines identified here are summarized and listed in a table for each impurity species as the database for EUV spectroscopy using fusion plasmas.
文摘Interests in the extendibility are growing after the introduction of the LPP (Laser Produced Plasma) EUV source technology in the semiconductor industry, towards higher average power and shorter wavelength, based on the basic architecture of the established LPP EUV source technology. It is discussed in this article that the power scaling of the 13.5nm wavelength source is essentially possible by a slight increase of the driving laser power, CE (Conversion Efficiency) and EUV collection efficiency by some introduction of novel component technologies. Extension of the EUV wavelength towards BEUV (Beyond EUV), namely 6.x nm is discussed based on the general rule of the UTA (Unresolved Transition Arrays) of high Z ions, and development of multilayer mirrors in this particular wavelength region. Technical difficulties are evaluated for the extension of the LPP source technology by considering the narrower mirror bandwidth and higher melting temperature of the candidate plasma materials. Alternative approach based on the superconducting FEL is evaluated in comparison with the LPP source technology for the future solution.
基金supported by National Natural Science Foundation of China(Nos.12172356,U23B20110)the Interdisciplinary and Collaborative Teams of CAS。
文摘Particle-In-Cell(PIC)simulations were performed in this work to study the dynamics of the EUVinduced hydrogen plasma.The Monte-Carlo Collision(MCC)model was employed to deal with the collisions between charged particles and background gas molecules.The dynamic evolution of the plasma sheath,as well as the flux and energy distribution of ions impacting on the mirror surface,was discussed.It was found that the emission of secondary electrons under the EUV irradiation on the ruthenium mirror coating creates a positively charged wall and then prevents the ions from impacting on the mirror and therefore changes the flux and energy distribution of ions reaching the mirror.Furthermore,gas pressure has a notable effect on the plasma sheath and the characteristics of the ions impinging on the mirrors.With greater gas pressure,the sheath potential decreases more rapidly.The flux of ions received by the mirror grows approximately linearly and at the same time the energy corresponding to the peak flux decreases slightly.However,the EUV source intensity barely changes the sheath potential,and its influence on the ion impact is mainly limited to the approximate linear increase in ion flux.
