Optics 101

Krypton Fluoride Excimer Laser – Properties and Applications

The krypton fluoride (KrF) laser is an excimer laser, which emits deep ultraviolet wavelengths. It consists of two elements, krypton and fluorine, as the lasing medium. The principle behind the working of the laser is that krypton absorbs energy from the power source and reacts with fluorine gas to produce krypton fluoride, a temporary complex. This complex is a cable of stimulated emissions, resulting in an exciplex laser in the near ultraviolet region of the electromagnetic spectrum, having a wavelength of 248nm.

Most excimer lasers are a combination of a noble gas and a halide. They are built on an electronic transition principle, and the emitted radiation is predominantly in the UV spectral range. Commonly used excimer lasers are krypton fluoride, argon fluoride, xenon fluoride, and xenon chloride. Safety precautions need to be exercised while working with this laser, as it damages the human eye when exposed to the UV radiation. Human flesh also needs to be protected from the potentially carcinogenic effects of UV radiation from this laser.

Applications of krypton fluoride laser are mainly in deep-ultraviolet photolithography. A number of microelectronic devices are manufactured by photolithography. After the discovery of excimer lasers in 1982, lamp-based lithography techniques became obsolete. Apart from photolithography, krypton fluoride lasers are used in nuclear fusion energy research, production of soft X-ray emissions, micromachining of plastics, composite materials, and organic tissues. Since the krypton fluoride laser emits deep ultraviolet radiation it is used in medical surgery and therapy.

Laser Properties

Laser Properties
Laser type Gas
Pump source High Voltage Electric Discharge
Operating Wavelength 248nm

Applications

The most important application of a krypton fluoride laser is in photolithography, for the manufacture of microelectronic devices. Use of this laser for lithography has not only replaced the use of mercury-xenon lamps, but has also provided much more precise and finer resolution solutions to photolithography techniques. Some of the other applications of the krypton fluoride laser are given below:

  • Nuclear fusion energy research
  • Production of soft X-rays from plasma
  • Micromachining of materials such as plastics, crystals, and composites
  • Medical therapy and surgery
  • Dental surgery

References

  • Krypton Fluoride Excimer Laser – World of Lasers

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