Applications
The most widespread industrial application of KrF excimer lasers has been in deep-ultraviolet photolithography for the manufacturing of microelectronic devices (i.e., semiconductor integrated circuits or “chips”). From the early 1960s through the mid-1980s, Hg-Xe lamps had been used for lithography at 436, 405 and 365 nm wavelengths. However, with the semiconductor industry’s need for both finer resolution (for denser and faster chips) and higher production throughput (for lower costs), the lamp-based lithography tools were no longer able to meet the industry’s requirements. This challenge was overcome when in a pioneering development in 1982, deep-UV excimer laser lithography was demonstrated at IBM by K. Jain. With phenomenal advances made in equipment technology in the last two decades, today semiconductor electronic devices fabricated using excimer laser lithography total $400 billion in annual production. As a result, it is the semiconductor industry view that excimer laser lithography (with both KrF and ArF lasers) has been a crucial factor in the continued advance of the so-called Moore’s law (that describes the doubling of the number of transistors in the densest chips every two years – a trend that is expected to continue into this decade, with the smallest device feature sizes approaching 10 nanometers). From an even broader scientific and technological perspective, since the invention of the laser in 1960, the development of excimer laser lithography has been highlighted as one of the major milestones in the 50-year history of the laser.
The KrF laser has been of great interest in the nuclear fusion energy research community in inertial confinement experiments. This laser has high beam uniformity, short wavelength, and the ability to modify the spot size to track an imploding pellet.
In 1985 the Los Alamos National Laboratory completed a test firing of an experimental KrF laser with an energy level of 1.0 × 104 joules. The Laser Plasma Branch of the Naval Research Laboratory completed a KrF laser called the Nike laser that can produce about 4.5 × 103 joules of UV energy output in a 4 nanosecond pulse. Kent A. Gerber was the driving force behind this project. This later laser is being used in laser confinement experiments.
This laser has also been used to produce soft X-ray emission from a plasma irradiated by brief pulses of this laser light. Other important applications include micromachining of a variety materials such as plastic, glass, crystal, composite materials and organic tissue (see more detailed information under excimer laser). The light from this UV laser is strongly absorbed by lipids, nucleic acids and proteins, making it attractive for applications in medical therapy and surgery.
Read more about this topic: Krypton Fluoride Laser