ArF laser

In photo CVD, the chemical reaction is activated by the action of photons, specifically ultraviolet (UV) radiation, which have sufficient energy to break the chemical bonds in the reactant molecules. In many cases, these molecules have a broad electronic absorption band and they are readily excited by UV radiation. Although UV lamps have been used, more energy can be obtained from UV lasers, such as the excimer lasers, which have photon energy ranging from 3.4 eV (XeF laser) to 6.4 eV (ArF laser). A typical photo-laser CVD system is shown schematically in Fig. 5.14.117]... 

Argon (Ar), 17 343. See also ArF laser bulk quantities of, 17 363 commercial distribution of, 17 362-363 cryogenic shipping, 8 40 doubly ionized, 14 684—685 economic aspects of, 17 365-366 electrostatic properties of, 1 621t in ethylene oxidation, 10 651 gas bulk separation, l 618t high purity, 13 460, 468 in light sources, 17 371-372 liquefaction, 8 40... 

We thank Lany Stillwagon for many helpful discussions, Norris Hobbins for assistance with XFS measurements, Vic McCrary and Vince Donnelly for exposures with the ArF laser and Ray Cirelli for deep-UV stepper exposures. 

Thermal effects can be overcome by vapourizing samples with ultraviolet (UV) KrF and ArF lasers, thus making possible in situ oxygen isotope analysis of silicates (Wiechert and Hoefs 1995 Fiebig et al. 1999 Wiechert et al. 2002). 

With LA-ICP-ToF-MS, using the 193 nm ArF laser (laser energy lOOmJ at 120(xm laser beam diameter), a depth resolution of 200 nm per laser shot was measured.121 LA-ICP-MS was utilized for depth profiling of copper coatings on steel with certified copper coating thicknesses from about... 

Figure 21-4 Atomic fluorescence from Pb at 405.8 nm. Water containing parts per billion (ppb) of colloidal PbC03 was ejected from a capillary tube and exposed to a 6-ns pulse of 1 064-nm laser radiation focused on the drop. This pulse created a plume of vapor moving toward the laser. After 2.5 xs, the plume was exposed to a 193-nm laser pulse, creating excited Pb atoms whose fluorescence was measured for 0.1 ps with an optical system whose resolution was 0.2 nm. The figure shows a calibration curve constructed from colloidal PbC03 standards and the signal from tap water containing 2 ppb Pb. /From S.K.H0 and N. H. Cheung, Sub-Part-per-Billion Analysis of Aqueous Lead Colloids by ArF Laser Induced Atomic Fluorescence," Anal. Chem. 2005, 77, 193.]...

FIGURE 7. Laser induced fluorescence (LIF) spectrum of the CN(X2e+) fragment produced in the ArF laser photolysis of BrCN. Note that the recoil fragment energy is such that the recoil velocities of nascent CN produced with Br(2P3/ ) or Br(2p-]/2) fragments are 3.3 x 10 and 2.0 x 10 cm/s, respectively. The collision frequency will be up to a factor of six higher than it is at room temperature. 

The recent work on the photodissociation dynamics of this molecule has centered around the ArF laser wavelength at 193 nm. The frequency of this laser line corresponds to the excitation of the strong ) absorption band (3,174). This band cor-... 

Dornhofer, Hack, and Langel (180), in a detailed study of the fluorescence that is induced by an ArF laser, have been able to show that an intense ArF laser can distort the observed vibrational distribution by photodissociating CS radicals with v" > 5. The ArF laser absorption by CS will also produce electronically excited CS which, when it emits, will redistribute the vibrational populations. Probing the CS quantum state population under these conditions could distort the CS ground state populations. The LIF measurements will underestimate the amount of CS radicals that are produced, while the direct detection methods will overestimate the amount of S(3p) atoms because of the secondary photolysis of CS. The vibrational distribution of Lu et al. (178) will be less prone to this secondary photolysis because very low laser powers (< 1 mj) were used. Dornhofer, et al. concluded from their results that the S(3p)/S(J-D) ratio was 3, which is in reasonable agreement with the LIF measurements of Lu et al. 

Figure 4. Photofragmentation pattern of mass-selected CJ4 by ArF laser (15 mj cm 2) with about 3 ps allowed between the ArF laser pulse and mass selection of the fragment ions. Note that CJ0 is only about twice as prominent as its neighbours. The Cf4 peak is downwards because the data presented is the difference between excimer laser on and excimer laser off.

Kinetic measurements were made by monitoring the laser-induced fluorescence of CH following the excitation in the (0-0) band of the X — A transition as a function of the time delay after the ArF laser dissociation. In the absence of any added reactants, CH had a decay time of 100 to 300 /isec at a total pressure of 30 to 100 torr (CHBr3 pressures of 1 to 10 mtorr) which can be attributed mainly to the CH + CH reaction. The addition of the reactants listed in Table I shortened the CH radical decay times considerably, indicative of some removal process involving a bimolecular mechanism since the total pressure was always maintained constant. Least squares plots of the inverse lifetimes of CH radicals versus the partial pressure of the added reactant yielded... 

Fujiwara, T. et al. (1997) Second-harmonic generation in germanosilicate glass poled with ArF laser irradiation, Appl. Phys. Lett., 71, 1032-4. 

Poster 16. Sung Kwan Kim, Yang-Soo Kim and Kwangsoo No (Korea Advanced Institute of Science and Technology) The Electronic Structures and Optical Properties of Hf-O-N Thin Films as a Phase Shift Mask for ArF Laser Lithography... 

The primary steps of the photolysis of aqueous monuron and diuron were investigated by Canle et al. by means of transient absorption spectroscopy using an ArF laser (X = 193 nm) for excitation [89]. Under these conditions, photoionization occurred with a quantum yield of about 10%. Radical cations were detected after the laser pulse and found to deprotonate to yield neutral radicals [89]. 

Laser-induced chemical hquid deposition of copper fihns on qnartz and glass from Cn(acac)2 (7a) as precnrsor was reported by Onchi and collaborators 2. The process is realized throngh the interaction of copper coUoids with the appropriate snrfaces. It was fonnd that, depending on whether the laser irradiation is discontinnons (ArF laser) or continnons (KrF laser), closed copper fihns or nano-islands were formed. This method differs from the laser-assisted liqnid-phase metallization of polymers, wherein a laser beam was nsed to enhance chemical rednction of copper(II) salts. ... 

ArF laser photolyis of H2S seeded in free-jet expansion of Ar used to form Sj. Analysis of LIF spectrum Lifetimes for two vib-rotational levels of Te2(A0 ). Cross-sections for deactivation by Tej Laser emissions from different excited Tcj isotopes Quantum yields for CI2 luminescence at wavelengths 308 nm following VUV excitation in the presence of Ar, Kr, and Xe f Three bound-free transitions observed in LIF from Brj following excitation at 158 nm. Collisional transfer by SF, N2, and He t Near-dissociation behaviour of l2(B n ) tLIF-Fourier transform study of the "near-dissociation behaviour of IjfBO I). Precise value for the well depth of the X state determined... 

Fluorescence liftimes of the predissociative NO(B n),u = 7 state measured in pure NO and in the presence of O2, N2, H2, Ar, and He have been reported. A value of 0.33 0.03 (xs was obtained for the zero-pressure lifetime from which an estimation of the value for the quantum yield of fluorescence of 0.15 was made. ArF laser radiation was used to excite rotational levels between J = 45/2—67/2, the energies of which exceed the dissociation limits of both the B IIi,2.t = 7 and = 7 states. Quenching... 

ArF laser excitation of the S state. Transient spectrum suggested to be due to hot Sq Cf,Hf, with 624 kJ mol" excess of internal energy... 

Exposures of PMMA with an ArF laser at 193 nm were reported by Kawamura et al. (207). The laser beam was focused by a convex lens to increase the power density. The laser beam dose incident on the resist film was 930 mj/cm, delivered in 20 nsec. Kawamura et al. were able to image 0.5-jim lines without interference patterns. 

The temporal response of the sensor (in units of output voltage V) made of an HOD film is shown by solid squares in Figure 13.17 [431]. The sensor was irradiated by an ArF laser (193 nm), where a DC bias of 10 V was applied between the interdigited electrodes. The FWHM of the laser pulse was roughly 5 ns, and it is seen that the sensor followed almost exactly the laser pulse in nanosecond time scale. A direct irradiation of the ArF laser on the UV sensor caused no damages at all. The open circles in Figure 13.17 correspond to the temporal response of an UV sensor made of polycrystalline diamond film. The sensitivity is at least five times inferior to that of the HOD UV sensor. The poor sensitivity of the UV sensor made of polycrystalline diamond film can... 

Figure 13.19. Photoresponse (output voltage) of diamond UV sensor against irradiations of ArF and dye lasers. The sensitivity to the ArF laser is 100 times better than to the dye laser [430].

The composition of the samples on the tungsten strips was determined using the surface mass spectrometer. A KrF laser (60 pJ in a 0.25 mm spot) was used for desorption, and ionization was accomplished with an ArF laser (200 jJ in a 1.5 mm spot). The mass spectra of the films from runs a and b are displayed in fig. 1. Spectrum a shows that sample a consists almost entirely of Cso- The observed Cm/Cto peak ratio is 12. Small peaks of CJg, and... 

Cm also appear. Spectrum b is similar, except that the Cio/Cyo peak ratio is reduced to 2.1. Therefore sample b, produced at the higher cell temperature, has six times more C70 relative to Cao than sample a. The mysterious long tails to the high mass sides of both the Cfto and C70 peaks are not yet understood, but they may be reaction products with air. The variation of the tail signals with ArF laser fluence suggests that these species are one-photon ionized and... 

Deutsch and Rathman193 showed that using an ArF laser beam parallel to the substrate, tungsten depositions can be obtained in a H2/WF6 gas mixture at 8 Torr. The substrate temperature was varied between 200 and 440°C. At 440°C, the bulk resistivity was about 17 /rOcm. However, below 350°C, high resistivity (100-300 /iflcm) /3-W is obtained. By a heat treatment at 650°C in H2 the /3-W phase can be converted into the a-W phase. The activation energy found for the photo reaction was 40.7 kJ/mole. 

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