Excimer lamps sources

Excimer lamps, a relatively recent new development, represent a new class of monochromatic UV sources. Excimers (excited dimers, trimers) are weakly bound excited states of molecules that do not possess a stable molecular state. ... 

Excimer lamps are quasi-monochromatic light sources available in UV wavelengths. The light is produced by silent electrical discharge through gas in the gap between two concentric quartz tubes. Electronically activated molecules are produced in the gas phase and decompose within nanoseconds to produce photons of high selectivity. This process is similar to the process in excimer lasers. 

With the narrow range of wavelength of the excimer lamp, a specific initiator can be selected with the maximum efficiency in that range. Thus, it is possible to reduce the amount of photoinitiator from that used for conventional UV sources and reduce the cost of the material and amounts of unreacted initiator in the finished coated substrate. Excimer lamps can be used for both free radical and cationic photoinitiators. ... 

Fusion Systems (Gaithersburg, MD) at one time offered 240 W/cm microwave-driven excimer lamps within its VIP (Versatile Irradiance Platform) series. They were among the most powerful sources of UV radiant power,i available... 

Anofher developmenf is free radical polymerization of neaf acrylafes wifhouf phofoinifiafor using 172 and 222 nm excimer lamps. Photons emitted from fhese radiafion sources are absorbed by many acrylafes generafing free radicals direcfly. ... 

Ushio America, Inc. www.ushiosemi.com UV equipment, UV light sources, UV excimer lamps... 

The narrow bandwidth emission is shown for the Xe excimer lamp (172 + 12 nm, Figure 17). The monochromacy of the light source is a great advantage in many preparative applications [2, 3, 66] and facilitates radiant power and irradiance measurements and calculations [2, 3] in up-scaling projects. 

Eximer light sources may require water cooling for optimal operation. Their life times have not yet been determined, but excimer lamps (see Table 1) have been operational for more than 3000 hours with radiant efficiencies of approximately 6%. 

FIGURE 31. The refractive index variation in the PMPS film by UY-light irradiation using different light sources (a) excimer lamp (308 nm) and (b) mercury-arc lamp (185, 254, 303 nm). (Reprinted from Ref. 134.)... 

When the excimer lamp of 308 nm is used for the irradiation light source, the refractive index lowers from 1.70 to 1.63. With the mercury-arc lamp the refractive index lowers to 1.58. The larger reduction of the refractive index with the shorter wavelength light derives from the elimination of the side-chain phenyl group. 

We used the UV/ozone cleaning method for the cleaning of substrates [43], An Xe excimer lamp with the wavelength 172nm (UER 20-172, Ushio Inc.) was used for the UV light source. The principle and method of the UV/ozone cleaning are described below. 

In addition, a novel generation of lamps with promising features for photochemical applications has been developed to industrial maturity over the last decade, the so-called incoherent excimer radiation sources (Eliasson et al., 1988). Note that these lamps are not laser sources. In contrast to well-known excimer lasers, excimer lamps are operated under different physical conditions and they emit incoherent electromagnetic radiation. Whereas pulsed laser radiation can reach very high irradiances, E up to 100 MW m , the irradiance E of excimer lamps is only in the range of 1000 W m . ... 

In the H2O-VUV AOP no additional auxiliary oxidants must be used to produce sufficient amounts of OH radicals. The technical development of incoherent exci-mer VUV and UV sources of electromagnetic radiation (see Chapter 4.3) led to a renaissance of research related to water photolysis. Hence, the experimental conditions and results of several recent investigations that deal with the applications of VUV and UV incoherent excimer lamps in the field of AOP research (mainly in aqueous media) are briefly summarized in Tab. 7-2. 

The incoherent excimer radiation from a dielectric barrier discharge (silent discharge), operating in pure xenon, gas mixtures of krypton/chlorine, and xenon/chlorine, provides intense narrow-band radiation. More details about the excimer UV sources can be found in the literature [236, 237]. As irradiation sources a XeCl (308 nm), a KrCl (222 nm), and a Xe2 (172 nm) excimer lamp were selected. Excimer lamps based on fluorine-containing excimers are difficult to operate, due to etching of the quartz housing by the F2. 

A typical example of a stepper is shown in Figure 5.4. Nikon Co. started selling the ArF immersion scanner NSR-S622D in February 2013. The ArF excimer lamp (193 nm) is equipped for a light source. This immersion system improved resolution effectively. A resolution of 38 nm is achieved by the scanner. The reduction ratio is 1 4. The NA of the system is 1.35. The maximum... 

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