Successful with Excimer Laser Solutions

01/2018 Entwicklung und industrielle Anwendung 32. JAHRGANG

Potenzial von Dense Wavelength Multiplexing steigert die Strahlqualität signifikant

BrillanteSuccessful Strahlqualität with Excimer bei DiodendirektlaserLaser Solutions Trumpf Chef Roger Kluth im Interview An interview with Richard Waldermann, General Manager and Vice President, Excimer Laser Business Unit, Coherent in Goettingen / Germany

Interview Anwenderbericht Messebericht ERP als Treiber der Management bei der Kist Laser World of Photonics ler Modernisierung von In München traf sich der Mess-Elektronik -flexibel Lasermarkt und zeigte sich Geschäftsprozessen? und investitionssicher optimistisch Wandel der ERP-Systeme Special Issue in Zeiten

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Successful with Excimer Laser Solutions The Coherent Excimer Business Unit, which began as Lambda Physik, has a 40 year history in producing excimer lasers for industrial and scientific applications. Here we interview company General Manager Richard Wal- dermann on the current state of excimer lasers and their future prospects.

Keywords: Excimer Laser, ELA – Excimer Laser Anneal- ing, LLO – Laser Lift-Off, LASIK

LASER: What is the Coherent Excimer are now for complete laser systems Business Unit? which include sophisticated beam de- Richard Waldermann, General Waldermann: Located in Goettingen, livery optics. Manager and Vice President, Excimer Laser Business Unit, this group develops, manufactures Coherent in Goettingen / Germany: and markets excimer lasers. We also The Excimer Business Unit has en- “A major factor in our success against provide applications development joyed tremendous success, particular- other excimer laser producers has support and after sales service from ly over the past ten years. We have in- been the ability to deliver a total system, including both laser and beam this location. While I imagine that creased our floor space over that time delivery optics, which I mentioned at most readers are aware that Coher- by a factor of five to approximately the outset.” ent at its Goettingen site – formally 20,000 m2². And, that expansion has operating under the name of Lambda also included equipment and infra- Physik – has long been a leader in ex- structure for automated testing and cimer laser technology, many people quality control that have dramatically may not realize that, over the years, improved the reliability of our prod- our expertise has expanded to include ucts to meet highest industry stand- New Coherent Factory for Assembly beam delivery systems. In fact, the ards. One important aspect of this has and Test of LineBeam Systems 2 in Goettingen vast majority of our equipment sales been the installation of 5,000 m ² of cleanroom space in our production environment. We now perform all product assembly under cleanroom conditions including all testing and laser tube production.

LASER: What markets and applications do you currently serve? Waldermann: Our excimer products support a very diverse range of applications. In terms of sales volume, the single biggest is Excimer Laser Annealing (ELA) for the flat panel display market. ELA is the standard production process in the fabrication of AMLCD and AMOLED displays used on

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virtually all advanced smartphones. ing application for us is Laser Lift-Off The products we supply for ELA are (LLO), which is utilized in the fabrica- our VYPER excimer lasers and line tion of flexible displays, such as are beam optics, comprising LineBeam already being employed in certain Systems which deliver the high ener- smartphones. Here, again, the exci- “Our excimer products support a very diverse range gy pulses in a long line beam that per- mer output is formed into the shape of applications. In terms of sales volume, the single forms silicon annealing at market-en- of a long, thin line beam, which we biggest is Excimer Laser Annealing (ELA) for the abling throughput rates. However, this call “UV blade.” The finished panel is flat panel display market.” has been a “moving target” because scanned underneath the line beam in display manufacturers keep increas- order to ablate an ultra-thin layer of ing the size of their panels as well material holding it to the rigid glass as the pixel density of their displays. substrate on which it was produced. These changes pose increased optical The result is a finished, functional dis- challenges for us, but we have man- play which is as flexible as a piece of aged to increase both the productiv- paper. With ELA and LLO, the excimer ity and the quality of the line beam. laser advances display production to Around 10 years ago, a production ELA a bright and flexible future. system required a 370 mm line beam combined with our 300W UV laser; In terms of unit volume, our single today, it is 1,600 mm driven by 3.6 kW biggest application is LASIK (La- UV power. ser-Assisted in Situ Keratomileusis), a surgical procedure that enables LASER: There are other solutions of more than a million people per year Excimer Lasers … to reach their perfect vision. We’ve Assembly of Line Beam Optical Waldermann: An important develop- serviced the LASIK market for more Components at Coherent in Goettingen

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than 20 years, but here, too, the lasers system together in close cooperation have steadily improved in terms of to achieve this high level of system their performance, reliability and ease optimization. of use. Currently, our main focus for LASIK products is to deliver new con- LASER: What is the outlook for exci- trol concepts and an advanced mod- mer lasers? ularity which will simplify their opera- Waldermann: Excimer lasers offer a tion. unique combination of deep ultraviolet (UV) output, together with high pulse “Excimer lasers offer a unique combination of We also support numerous other in- energy, which can’t be equaled by any deep ultraviolet (UV) output, together with high dustrial and research applications, other type of laser or light source. The pulse energy, which can’t be equaled by any other including Fiber Bragg Grating (FBG) short excimer wavelengths enable type of laser or light source. The short excimer writing and Pulsed Laser Deposition the production of very small features wavelengths enable the production of very small (PLD). The latter is a unique method at extremely high precision because features at extremely high precision because for producing high quality thin films, optical resolution scales directly with optical resolution scales directly with wavelength, which eliminates thermal effects at wavelength, due to diffraction. Also, due to diffraction. Also, UV light doesn’t penetrate the substrate. There are many excit- UV light doesn’t penetrate very far very far into most materials, which limits the laser ing potential application areas for this. into most materials, which limits the affected area.” laser affected area. Additionally, high LASER: What do you see as your key pulse energy, combined with rapid advantages over your competition in repetition rate, enables high process these areas? throughput using excimer lasers. No Waldermann: A major factor in our other laser technology can provide success against other excimer laser UV light at wavelengths like 308 nm, producers has been the ability to de- 248 nm, 193 nm or 157 nm with the kind liver a total system, including both la- of output power that an excimer pro- ser and beam delivery optics, which I duces. mentioned at the outset. There are of- ten many different ways in which our These characteristics are important customers could potentially perform because in nearly every field we their particular process, including support – including microelectronics, laser and also non-laser based solu- displays, new energy, mobility, bio- tions. Therefore, we have to present technology and even basic research – a highly optimized solution, in terms there are two overarching trends: The of both its performance and total cost first is the need to produce smaller, of ownership, in order to be success- higher precision features and thinner Final Assembly and Test of LineBeam 1300 Optical System with VYPER ful. We’ve found that it is necessary films, and the second is to accomplish Excimer laser to design the laser and beam delivery these processes at higher speed and All Pictures: Coherent lower cost. The output characteristics of excimer lasers make them inherent- ly better at satisfying the first of these requirements, while our ongoing im- provements in their performance, reliability and cost-of-ownership keep them competitive in the latter. All this makes the future of excimer lasers look exceptionally bright.

Our special thanks go to Richard Waldermann, Rainer Paetzel and Petra Wallenta for making this happen !

Coherent · www.coherent.com