Discharge medium uniformity influence on XeCl excimer laser beam quality (original) (raw)

Investigation of the characteristics of an excimer laser with a narrow emission line

Soviet Journal of Quantum Electronics, 1990

An investigation was made of the spatial coherence of excimer lasers in different resonator geometries. Lasing with a spectral width of 5 nm was obtained in a scheme using a grating in the autocollimation regime and a four-prism telescope. A discussion is given of the questions involved in employing excimer lasers having a narrow laser emission line in photolithographic projection systems.

XeCl laser pumped by an electron beam and X-ray assisted discharge

Journal de Physique Lettres, 1981

2014 Une émission laser de longue durée (200 ns) et de rendement élevé a été obtenue à 3 080 Å à partir de l'excimère XeCl* à la suite de l'excitation de mélanges Ne/Xe/HCl à température ambiante et à très basse température par une décharge en régime d'avalanche assistée par un faisceau d'électrons et de rayons X. L'énergie apportée au milieu actif par la décharge était de plusieurs ordres de grandeur supérieure à celle apportée par le faisceau de préionisation. L'énergie spécifique laser maximale obtenue était de 3 J/1 à température ambiante pour une longueur de gain de 16 cm et une énergie apportée au milieu actif par la décharge égale à 150 J/l. Abstract. 2014 Long pulse (200 ns) XeCl excimer laser emission (03BB = 3 080 Å), has been obtained when Ne/Xe/HCl mixtures are excited by an electron beam and X-rays assisted discharge either at room temperature or at very low temperature. Absorbed discharge energy is several orders of magnitude higher than the absorbed beam energy. Maximum specific laser energy is 3 J/l at room temperature for a 16 cm gain length and an absorbed discharge energy of 150 J/1.

Space and time resolved discharge evolution of a large volume X-ray triggered XeCl laser system

Applied Physics B Photophysics and Laser Chemistry, 1992

The spatial distribution and the temporal development of the net gain have been measured in a ten liter active volume switchless discharge XeC1 laser. The experimental results are compared with both zero-dimensional and two-dimensional kinetic code predictions. The comparison between the results of the kinetic codes and of some measurements relevant to the time-dependent discharge homogeneity allows a deeper insight into the influence of the streamer evolution on the discharge characteristics.

Excimer laser gain by pulse shape analysis

IEEE Journal of Quantum Electronics, 1981

An analysis of the temporal emission of broadband tunable excimer lasers such as XezCl shows that the laser pulse can be described in terms of a Q-switch model rather than by steady-state considerations. For eiectron-beam (e-beam) pumped rare gas halide mixtures, transient absorption of the majority gas-usually argon-acts as a chemical Q-switch. The ring-up time of the delayed laser pulse may be conveniently used for optimization of the laser gas mixture.

Electric discharge pumping of excimer lasers

Le Journal de Physique Colloques, 1979

RBsumB.-Nous avons examink le rendement et l'agrandissement a l'bchelle des lasers a excimer (excitbs par de faisceau permet d'obtenir de haute energie spkcifique dans de grandes structures avec des courants de faisceau maintenue par faisceau Clectronique semble le plus prometteur pour l'obtention de grandes knergies. Les performances de ce type de laser peuvent Stre prddites grdce a un modble englobant l'analyse de la cinbtique des klectrons, de la chimie de la dbcharge et le rksonateur optique. Les limitations introduites par les problkmes de stabilitt de dkcharge sont minimiskes grPce a l'emploi d'un faisceau Clectronique uniforme. Cette bonne uniformitb de faisceau permet d'obtenir de haute energie spbcifique dans de grandes structures avec des courants de faisceau klectronique modCrts.

Diagnostics of a Compact Discharge-Pumped XeCl Laser with BCl3 Halogen Donor

Applied Physics B, 1991

The results of a comprehensive study of a compact UV-preionized XeC1 laser are presented. The subjects of this study were: discharge voltage and current measurements, dye laser probing of the active medium, and the mass spectrometry of gas mixture degradation products. It is shown that the gas lifetime was significantly improved when the laser was operated with BCla as a halogen donor instead of commonly used HC1. By the dye laser absorption and gain probing, the temporal and spatial dependences of the densities for several plasma components, Ne*, Xe*, Xe +*, CI-, XeCI* and of ground state boron atoms were measured. Some aspects of plasma kinetics for uniform and constricted phases of the discharge are discussed. By the mass spectrometry of gas mixture degradation products on long-term operation of the laser device several gaseous (N2, 02, CO2, H20 , C2H4) and solid (NiC12, H3BOa) products were detected in the laser chamber. NH4C1 was determined to be a stable fraction of the deposits on optics surfaces. The reasons for the improvement of gas lifetime for BC13-containing gas mixtures are discussed.

Numerical modeling of a XeCl laser excited by microwave discharge

Applied Physics B: Lasers and Optics, 1997

A comprehensive kinetic model for XeCl lasers excited by microwave discharge is formulated. In the model, the rate equations of reaction kinetics are solved self-consistently with the Boltzmann equation for electrons and the radiation transfer equation. The effective electric field strength needed in the solution of the Boltzmann equation is determined, by the energy balance argument, in terms of the microwave energy dissipated in the XeCl laser plasmas. The accuracy of the model is checked by comparing calculations with the experimental results reported by Christensen et al. in Optics Letters, 12, 169 (1987). Reasonably good agreements in the peak output power and laser efficiency have been achieved. Model calculations also predict that an efficiency as high as 2.7% can be obtained once the conditions of the above-mentioned experiments have been optimized. From the consideration that the skin depth effectively limits the absorption length of the microwave pumping and hence the excitable volume, it is concluded that high input power densities (≥ 2 MW/cm 3 ) and higher gas pressures (between 3 and 10 atm) are the preferable conditions to achieve higher efficiency. Preliminary calculations on CCl 4 containing XeCl gas mixtures show that improvement in laser efficiency by several folds may be achieved as a result of the higher intrinsic efficiency of excimer formation.

Kinetic modelling of a discharge-pumped ArF excimer laser and the effects of discharge filamentation

Applied Physics B, 2001

Results of kinetic modelling of an X-ray preionised, discharge-pumped ArF excimer laser, operating with a spikersustainer circuit are presented. The parallel-resistor model includes the complete ArF laser kinetics and calculations of the Boltzmann equation in each layer taking into account the effects of electron-electron and super-elastic collisions. The model further includes a detailed description of the electrical circuit and the formation of filaments with a realistic electrode profile. This model shows a good correspondence with the experimental results in predicting laser energy and optical behaviour. Neglecting the formation of filaments and the electron-electron and super-elastic collision processes yields remarkably poorer results. Parametric studies on the electrode profile, the formation of micro-arcs and on the electrical circuit parameters were performed numerically. : 42.55.Lt; 52.80.Hc; 42.60.By Recently, interest in the electric-discharge-excited ArF laser (λ = 193 nm) has grown strongly, due to its application possibilities in medicine and lithography. The processes taking place in the active medium of this laser were studied experimentally [1-9] and theoretically . The number densities of electrons, of negative fluorine ions and of several excited species were measured in [1-3], respectively. The optimisation of the gas mixture composition, the electrode construction, the electrical circuit and the application of a gas cleaning system yielded a laser efficiency of up to 2.1% [4], laser pulse energies of up to 550 mJ , pulse lengths of up to 120 ns [6] and increased gas-mixture life times of up to 10 9 pulses in one month . Numerically, the upper energy limit for a typical ArF laser pulse, as imposed by the development of micro-channels, was evaluated in the frame of a zero-dimensional model and for an idealised electric circuit . A one-dimensional fluid model was described in , to study the formation of cathode and anode layers and to investigate the effects of gas