![]() A reticle (mask) containing the desired circuit pattern is illuminated with UV laser light and the mask pattern is projected onto the wafer surface, after which the exposed resist is developed and the wafer is chemically etched to physically remove material from the exposed areas to produce the actual features. The detailed structure of these devices is built up layer by layer in a process called photolithography, with the first step being to coat a semiconductor wafer with a light-sensitive photoresist. And, the availability of ever-smaller, more powerful and, economical microprocessors has in turn had a profound impact on modern society.Īn IC itself consists of numerous electronic components constructed on a single, monolithic semiconductor wafer. PhotolithographyĮxcimer lasers are also essential to the fabrication of highly miniaturized integrated circuits (ICs). Plus, the short (nanosecond) pulse width and short wavelength remove corneal material in a relatively cold process called photoablation. The precision of the 193 nm argon fluoride (ArF) excimer laser ablation process is essential for the predictability and safety of the LASIK procedure. The flap is then replaced, sealing and protecting the front of the eye. The excimer laser beam is shaped and projected using fast-scanning mirrors, ablating corneal material in the precise pattern required to correct the individual patient's vision. To perform LASIK, a thin, hinged flap is surgically lifted (by a femtosecond laser or microkeratome) from the outer surface of the cornea. In the LASIK procedure, excimer laser pulses at 193 nm are used to ablate material from the human cornea to reshape it, thus changing its refractive power and allowing correction for short- or long-sightedness and astigmatism. What started with crude experiments on pig eyes has now evolved to more than 10,000 high-precision, compact, tabletop lasers deployed worldwide at eye clinics and LASIK centers. Introduced in 1989, LASIK was the first major non-scientific application for excimer lasers and still remains the largest single excimer laser application in terms of unit volume. Vision correctionĮvery year, more than a million people worldwide undergo LASIK surgery to achieve perfect vision-dramatically improving the quality of life for countless individuals (see Fig. Just as important, laser producers have also substantially improved the service characteristics and total cost of ownership of excimer lasers to keep them competitive with other laser and non-laser technologies. For example, the first commercial excimer laser, the Lambda Physik EMG 500, operated at a maximum repetition rate of 20 Hz-now, numerous excimer lasers support multi-kilohertz repetition rates (see Fig. While solid-state UV laser technologies have advanced tremendously over the past 40 years, no new technology has arisen to challenge the excimer laser in delivering this particular combination of characteristics.įrom a practical standpoint, excimer lasers have expanded their relevance in the market because of extensive efforts by manufacturers to improve their output characteristics and tailor them to the needs of specific applications. High pulse energy combined with rapid repetition rate enables high process throughput and reduces takt time (the total time it takes to produce a single unit of a product). The short wavelength enables the production of very small features at extremely high precision, based on the fact that optical resolution scales down directly with wavelength because of diffraction. Unique output, unique benefitsĮxcimer lasers offer a unique combination of UV wavelength output together with high pulse energy-attributes that are key to their e xpanding use. Laser-assisted in situ keratomileusis (LASIK), photolithography, and display production are three primary applications that illustrate the unique properties of the excimer laser that continue to ensure its legacy as a key enabling technology. It is fair to say that few other laser technologies have had a greater impact on our daily life than excimers. While most of the original applications for excimers can largely be relegated to history, many others have evolved. As soon as excimer lasers entered the market, Lambda Physik began to investigate other possible uses for a powerful source of short ultraviolet (UV) light. ![]() Interestingly, its developers-Bernd Steyer and Dirk Basting-were both chemists whose main goal was to develop a light source for photochemistry and dye laser pumping. The first commercial excimer laser was introduced 40 years ago by Lambda Physik (now Coherent Santa Clara, CA). ![]()
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