Fluorine excimer laser

A molecular fluorine excimer laser (157 nm) was also used to ablate PMMA chips to a depth of 500 pm [197], It was also reported that acrylic (or PMMA) plates were processed using a laser-cutting machine [198],... 

PE and PP films were irradiated in air with an argon-fluorine excimer laser (k = 193 nm) [53]. The 193 nm absorption coefficients, the penetration depths (calculated for 99% of the deposited laser energy), and the etch depths (given by the ratio between the thickness of the film and the number of shots before the film is pierced), at different fluences of the laser beam, for PE and PP, are presented in Table 2. 

Excimer lasers use gases, but because of their special properties are usually considered as a class of their own. Excimer is short for excited dimer, which consists of two elements, such as argon and fluorine, that can be chemically combined in an excited state only. These lasers typically emit radiation with veiy small wavelengths, in the ultraviolet region of the electromagnetic spectrum. This shorter wavelength is an enormous advantage for many applications. 

Figure 2 shows a schematic of the system that was used to flood expose the resist films. A Quanta Ray EXC-1 KrF excimer laser was used for all exposures. The laser output at 30 keV was 30-55 mJ/pulse/cm with a 0.33% fluorine, 5% krypton, and 94.67% neon gas mixture at 45 psig. The beam, at 100 pulses/sec., was reduced to a 3 mm diameter spot using aperatures. A 5 mm diameter light pipe was used to scramble the beam and improve uniformity. 

Farquhar J, Rumble D (1998) Comparison of oxygen isotope data obtained by laser fluorination of olivine with KrF excimer laser and CO2 laser. Geochim Cosmochim Acta 62 3141-3149 Farquhar J, Chacko T, Frost BR (1993) Strategies for high-temperature oxygen isotope thermometry A worked example from the Laramie Anorthosite Complex, Wyoming, USA. Earth Planet Sci Letters 117 407-422... 

Hosono, H., Mizuguchi, M., Kawazoe, H., and Ogawa, T., Effects of fluorine dimer excimer laser radiation on the optical transmission and defect formation of various types of synthetic SiOj glasses, Appl. Phys. Lett. 74, 2755 (1999). 

An interesting method was presented for the analysis of perfluorinated polyethers (PFPE) by Cromwell et al. The fluorinated polymers are commonly used as lubricants because of their low vapor pressures, chemical inertness, and thermal stability. Samples were examined in a cubic trap FTMS-2000 system using a 4.3 T magnetic field. Both a Kr/F excimer laser and a Nd/YAG laser were used for infernal LD. The fwo-step procedure involved using the 248-nm excimer laser for desorption of the polymer and, immediately following, a second more tighfly focused 532 nm laser ablation pulse to ablate metal cations from fhe surface beneath the polymer sample. Thus, cationization could be controlled, and the dynamics of the process are discussed. Mass spectra extended up to 10,000 Da are shown. 

A rate constant of 1.8x10 cm -molecule -s for Kr +NF2->KrF +NF was derived from the simulation of the degradation of a KrF excimer laser using NF3 as the fluorine donor... 

Laser mixtures. Mixtures of rare gases with nitrogen, and carbon dioxide with helium are used for lasers. Excimer lasers use the rare gases mixed with fluorine or hydrogen chloride. 

Different methods were developed and applied for the structure analysis and characterization of the polyesters properties. The morphology of the imsatu-rated polyester and vinyl ester networks was studied using the ArF excimer laser (A. = 193 nm, pulse duration time 16 ns, in air under atmospheric pressure) smface treatment, followed by SEM observations [157]. Samples were analyzed, after laser treatment, by profilometry to determine the ablation threshold. The differences between the thresholds at which ablation of various consistent phases of the materials occurs were used. That method enabled the determination of the two-phase structure of the vinyl ester matrices and the organized structme network of UPs. SEM analysis was also used for investigation of the compatibihty of imcured fluorinated UPR systems. The results were in good agreement with the macroscopic results obtained by visual inspection [72]. 

The active medium of the KrF laser is a mixture of krypton, molecular fluorine F2, and helium or argon as buffer gas. The whole gas system can be operated in a closed cycle where the gas is pumped from a reservoir through the laser channel. In the fast discharge, excited Kr and Ar atoms and ions are formed by electron impact. The excimers are formed by several reactions, for example. 

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