Source For EUV Lithography Research Articles

A synchrotron-based kilowatt-level radiation source for EUV lithography

A compact damping ring with a limited circumference of about 160 m is proposed for producing kilowatt-level coherent EUV radiation. The electron bunch in the storage ring is modulated by a 257 nm wavelength seed laser with the help of the angular-dispersion-induced micro-bunching method (Feng and Zhao in Sci Rep 7:4724, 2017), coherent radiation at 13.5 nm with an average power of about 2.5 kW can be achieved with the state-of-the-art accelerator and laser technologies.

Laser-Assisted Counter-Facing Plasma Focus Device as a Light Source for EUV Lithography

A pair of plasma focus devices was operated with a counter-facing configuration. The focus electrode consisted of six cathodes and a center anode, drove a multichannel discharge. The $2 \times 6$ multichannel discharges were triggered by a YAG laser, which also supplied lithium plasma as the radiation source. A high energy density lithium plasma was formed in the center of focus electrodes, which emitted radiation in an extreme ultraviolet region through the Lyman- $\alpha $ (2p-1s) transition of hydrogenlike lithium ions for pulse duration of more than microsecond. A proof of principle experiment and the latest advances toward realization of a high-average power system are shown.

Laser wavelength dependence on angular emission dynamics of Nd : YAG laser-produced Sn plasmas

We investigated the laser wavelength effect on angular atomic and ionic emission from laser-produced Sn plasma, since it is regarded as a viable candidate for an EUV lithography source. For producing plasmas, the fundamental, second and fourth harmonics radiation from a Nd : YAG laser were used. The angular variation of atomic and ionic particle analysis was carried out using quartz crystal microbalance and Faraday cups by moving them in a circular path at a constant distance from the target normal. Along with atomic and ionic emission, we also compared the plasma emission features in the visible and EUV spectral regions. Results indicate strong forward bias in atomic and ionic plasma debris at all wavelengths. Shorter wavelength plasmas are found to generate more atomic particles while ion flux showed a similar trend irrespective of the excitation wavelength.

Source for extreme ultraviolet lithography by the tabletop storage ring MIRRORCLE

Advances of electron storage rings to beam currents of above 1 A and tabletop sizes make possible the development of a synchrotron-based source for EUV lithography (EUVL) at ~13.5-nm wavelength. The MIRRORCLE storage rings can provide on average 3-A electron beam current, 1-min lifetime, 15-ms radiation damping, and beam size ~3*3 mm2. MIRRORCLE-20SX, MIRRORCLE-6X, and MIRRORCLE-CV4 store electrons with energies of 20 MeV, 6 MeV, and 4 MeV, respectively. These machines can emit EUV from a tiny target, hit by the circulating beam, via transition radiation or diffusive radiation. Using a multilayer microelectromechanical system (MEMS) target allows enhancement and spectral purification of the emitted EUV. Aligning many such MEMS along the electron beam orbit and radiation collection by only one quasi-elliptical EUV mirror can provide EUV satisfying the joint requirements for an EUVL source.

High power fiber laser driver for efficient EUV lithography source with tin-doped water droplet targets

In this paper we report the development of nanosecond-pulsed fiber laser technology for the next generation EUV lithography sources. The demonstrated fiber laser system incorporates large core fibers and arbitrary optical waveform generation, which enables achieving optimum intensities and other critical beam characteristics on a laser-plasma target. Experiment demonstrates efficient EUV generation with conversion efficiency of up to 2.07% for in-band 13.5-nm radiation using mass-limited Sn-doped droplet targets. This result opens a new technological path towards fiber laser based high power EUV sources for high-throughput lithography steppers.

Review of the 4th NLTE Code Comparison Workshop

We review the critical results of the 4th Non-LTE Code Comparison Workshop held in December 2005. To test the NLTE population kinetics codes, both steady-state and time-dependent cases for C, Ar, Fe, Sn, Xe, and Au plasmas were selected for detailed comparisons. Additional features such as the effects of non-Maxwellian free electrons, the influence of a Planckian radiation field, and the emission spectra were required in specific cases. The scope of problems was expanded from the previous workshops to include two problems outside the dense plasma physics, namely, the EUV lithography sources and the astrophysical photoionized plasmas. We briefly outline the technical organization of the workshop, present motivations for the chosen cases, and discuss some representative results.

Development of EUV Lithography Source Based on Laser-Produced Plasma

Development of EUV Lithography Source Based on Laser-Produced Plasma

Integral characteristics of spectra of ions important for EUV lithography

The emission spectrum corresponding to the 4p54dN+1 + 4p64dN–14f → 4p64dN transition array is concentrated in a narrow interval of wavelengths. That is due to the existence of an approximate selection rule and quenching of some lines by configuration mixing. Thus such emission of elements near Z = 50 is considered to be the main candidate for the EUV lithography source at λ = 13.5 nm. In the present work the regularities of these transition arrays are considered using their integral characteristics: average energy, total line strength, variance and interval of array containing some part of the total transition probability. Calculations for various ions of elements In, Sn, Sb, Te, I and Xe have been performed in a two-configuration pseudorelativistic approximation, which describes fairly well the main features of the spectra. The variation in the values of the main integral characteristics of the spectra with atomic number and ionization degree gives the possibility of comparing quantitatively the suitability of the emission of various ions for EUV lithography.

Multi-foil optic condenser for a laser plasma EUV source

Design and development of the multi-foil optic (MFO) condenser for a gas puff laser plasma source for EUV lithography is presented. The MFO in general is a soft x-ray optic which consists of two perpendicular sets of very thin reflecting surfaces, where photons are reflected at grazing angles. The aim of the work was to design the condenser working for ∼100 eV photons focusing from point to point ∼40 cm distant. Initial design and simulations are described and compared to early experiments performed in visible light. The performance of the optic over the initial requirements is discussed. We also briefly discuss several other MFO modifications, including condensers and collimators for laboratory purposes or the wide field x-ray scanning modules for satellite astronomy.

HEIGHTS initial simulation of discharge produced plasma hydrodynamics and radiation transport for extreme ultraviolet lithography

Discharge-produced plasma (DPP) devices have been proposed as a light source for EUV lithography. A key challenge for DPP is achieving sufficient brightness to support the throughput requirements of exposure tools for high-volume manufacturing lithography. To simulate the environment of the EUV source and optimize the output of the source, an integrated model is being developed to describe the hydrodynamic and optical processes that occur in DPP devices. The model includes both plasma evolution and magnetohydrodynamic processes as well as detailed photon radiation transport. The total variation diminishing scheme in the Lax-Friedrich formulation for the description of magnetic compression and diffusion in a cylindrical geometry is used. Several models are being developed for opacity calculations: a collisional radiation equilibrium model, a self-consistent field model with Auger processes, and a nonstationary kinetic model. Radiation transport for both continuum and lines with detailed spectral profiles are taken into account. The developed models are integrated into the HEIGHTS-EUV computer simulation package. Preliminary results of a numerical simulation of xenon gas hydrodynamics and EUV radiation output are presented for various plasma conditions.

A novel fast capillary discharge system emitting intense EUV radiation: Possible source for EUV lithography

The performance of a novel and truly compact xenon-filled fast capillary discharge system has been studied by making spectroscopic and pinhole imaging measurements. A few kA current having a fast rise time was applied across the xenon-filled alumina capillary (0.8–1.2 mm diameter and 10–30 mm long) to produce radiation mostly in the EUV region (10–16 nm). The EUV radiation from the capillary was characterized by employing EUV spectrometers and a EUV pinhole camera. Time-integrated, as well as time-resolved, spectra furnished information about the radiation processes from the xenon plasma along with the wall of the capillary. A ‘super’ fast pinching effect is indicated from the pinhole images. The results obtained from the EUV spectroscopic and pinhole measurements are incorporated in this paper. This EUV source may be a strong contender for the basis of next generation lithography assembly.

A gas discharged based radiation source for EUV-lithography

A new high repetitive, compact and low cost gas discharge based EUV ''lamp'' has been studied as an alternative to laser-produced plasmas as EUV sources. First results using oxygen in a fast discharge of electrically stored energy around 1 J lead to a conversion efficiency of about 0.1 % for the emission at 13.0 nm which is suited for the use with Mo/Si-multilayer mirrors. Using Xenon a broadband emission in the investigated wavelength range from 10 nm to 18 nm is observed. With a first version a source with 40 W electrical input power could be demonstrated that emits about 50 mW/([email protected]) around 13 nm at a repetition rate of 150 Hz. No debris and no electrode erosion was observed after more than 10^7 pulses done up to now. Making use of the remaining optimisation potential this concept seems to be promising to fulfil the requirements of extreme-ultraviolet lithography