Excimer laser system

Mt. Wilson Observatory. The UnISIS excimer laser system is deployed on the 2.5 m telescope at Mt. Wilson Observatory (Thompson and Castle, 1992). A schematic of the system layout is shown in Fig. 11. The30W, 351 nm excimer laser is located in the coude room. The laser has a 20 ns pulse length, with a repetition rate of 167 or 333 Hz. The laser light is projected from the 2.5 m mirror and focused at 18 km. A fast gating scheme isolates the focused waist. A NGS is needed to guide a tip-tilt mirror. Even with relatively poor seeing, UnISIS has been able to correct a star to the diffraction limit. 

Figure 3.60. Schematic diagram of a VUV excimer laser system for contact lithography with 157-nm radiation. (Reproduced with permission from reference 208. Copyright 1983 American Institute of Physics.)...

The excimer laser now has a lead extraction application (47-54). This laser, which once held much promise in angioplasty, is now used in endocardial lead extraction. Byrd, working with Spectranetics, developed a laser sheath to assist lead removal. The sheath was designed to work in conjunction with the Spectranetics CVX-300 excimer laser system (Fig. 6.38). The laser sheath consists of circumferentially arranged laser fiber bundles (Fig. 6.39). 

Geckos eyes have 350 times more sensitivity to color in dim light than human eyes. Newer-generation excimer laser systems used for vision-correction surgery have the capacity to measure and correct higher-order optical aberrations of the human eye. Iris recognition with a rotational adjustment is also available on some lasers. 

UV laser A generic name given to a laser ablation system that works in the ultraviolet region of the electromagnetic spectrum. The three most common wavelengths used in commercial equipment are all UV lasers. They include the 266 nm (frequency-quadrupled) Nd YAG laser, the 213 nm (frequency-quintupled) Nd YAG laser, and the 193 nm ArF excimer laser system. Also refer to excimer laser and Nd YAG laser. 

In an excimer laser the mixture of inert gas, halogen gas, and helium, used as a buffer, is pumped around a closed system consisting of a reservoir and the cavity. 

P. Schermerhom, Excimer Lasers Mpplications, Beam Delipey Systems and Laser Design, SPIE Vol. 1835, Society of Photooptical Engineers, Bellingham, Wash., 1992. 

A versatile Laser-SNMS instrument consists of a versatile microfocus ion gun, a sputtering ion gun, a liquid metal ion gun, a pulsed flood electron gun, a resonant laser system consisting of a pulsed Nd YAG laser pumping two dye lasers, a non-resonant laser system consisting of a high-power excimer or Nd YAG laser, a computer-controlled high-resolution sample manipulator on which samples can be cooled or heated, a video and electron imaging system, a vacuum lock for sample introduction, and a TOF mass spectrometer. 

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]... 

To summarize the state of technology for the chemist wishing to practice laser chemistry the laser devices exist with the capability one would like, but they are expensive. We may expect that cheaper pulsed laser systems based upon excimer, Nd YAG, N2, alexandrite, etc. may be in the offing in the near future. This has already begun to happen with a new generation of N2 pumped dye lasers from two manufacturers. No such prospects presently exist for c.w. lasers in the visible and ultraviolet, but one may hope that the ion laser will be radically improved or supplanted soon. For chemical applications which can use infrared excitation, satisfactory devices presently exist and the price is right. 

We have found the combination of the azide compound and the styrene resin is well suited for achieving high resolution and high aspect ratio patterns using KrF excimer laser stepper system, because of the absence of swelling-induced pattern deformation during alkaline development and the suitable optical density at 248 nm in terms of sensitivity. 

The film thickness of the resist was 1.0 micron. The exposure was done with a 5X KrF excimer laser stepper system (N.A 0.36) we manufactured (14). 

Figure 9 shows an SEM photograph of 0.6 micron down to 0.45 micron line-and-space patterns of the new resist in 1.0 micon film thickness exposed with KrF excimer laser stepper system (N.A. 0.36). The energy required for the pattern fabrication was only 50 mJ/cm2, and the development was done with a 60s immersion in 0.83% TMAH solution. High aspect ratio patterns of such thick resist films were successfully obtained using this resist. 

We achieved high aspect ratio sub-half-micron pattern fabrication in 1.0 micron film thickness using this new resist. We are convinced that this new resist could make possible simple and efficient single-layer-resist system for KrF excimer laser lithography. 

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