Optical technologies often form the basis for increased performance and better resource efficiency in the area of microelectronics. The increasingly smaller structure sizes and high integration density in semiconductor production can no longer be guaranteed by precision mechanical tools. Compared with traditional technologies, laser processing provides better quality, facilitates higher throughput and reduces production costs. That’s also true in electronics production. Dipl.-Ing. Rainer Pätzel from Coherent GmbH, Göttingen (Hall C1, Stand 321) assesses the latest trends in microtechnical electronic applications: “The rapid development in electronic products such as smartphones or tablet PCs is characterised by an increased scope of performance and, in particular, the miniaturisation of the different function units. The purposeful use of lasers enables semiconductor chips to be manufactured and integrated from microlithography of the integrated circuits through to exposure, laser drilling and microbonding of the printed-circuit boards. On the whole, laser applications are highly flexible. This is a substantial competitive advantage considering the short innovation cycles nowadays.”
Combined laser processing is revolutionising copper welding
Copper or precious metal alloys are normally used in the industrial production of integrated circuits. Both electronic and non-electronic components are welded onto these circuits using a laser beam. The advantage of laser beam welding is the high temperature stability of the joints through which complex modules are suitable even for application in the engine compartment of cars. The disadvantage of laser beam microwelding has so far been the high variation in the welding results, which is due to the strongly reflecting properties of non-ferrous and precious metals, and leads to high material rejects in production.
LASER World of PHOTONICS 2011 will feature a new process which guarantees reliable copper welding. A short-pulse laser, as a so-called pre-pulse module, starts the welding process and produces stable starting conditions for the following work of the infrared laser due to its high rate of absorption. This process represents a breakthrough with 100% reliability in laser beam material processing and can provide great momentum for the automation of microprocessing and for the assembly of components on printed-circuit boards.
Structuring of flexible surfaces harbours potential savings
Lower costs and environmentally compatibility are the main objective of miniaturisation and compaction tendencies which are common to all applications in the area of microelectronics. Conserving raw materials or replacing them by organic materials is an important starting point in this field. Printed electronics are therefore being promoted with great intensity in Germany, for example through use in organic and flexible solar cells, and OLED lighting and display technologies. Jens Hänel, CTO of 3D-Micromac AG, Chemnitz, (Hall C2, Stand 364): “We have been able to speed up the development of modular roll-to-roll systems in order to produce flexible organic solar cells. The use of ultra-short pulse lasers in this case guarantees the highest possible efficiency with maximum precision and minimum material damage while the roll-to-roll process permits high material throughput and correspondingly large processing areas. It is therefore possible to dramatically reduce the component manufacturing costs.”
System competence produces leading edges for laser manufacturers
Microprocessing lasers are also opening up new possibilities in the miniaturisation of semiconductor structures. Wherever the electrical properties of utilised standard materials do not allow any further miniaturisation or the costs of the structuring process become too high, the trend is towards multi-chip modules for example. Ultra-short pulse lasers can be used to drill so-called blind holes in the silicon substrate of every chip and therefore make them stackable. Stacking two or more microchips on top of one another represents the transition from planar to three-dimensional technology and leads to higher performance on each chip surface.
The new performance requirements for semiconductors also mean that laser manufacturers will need a greater understanding in future of the end product and the processes in the industries which they supply. Michael Lau, Sales Manager for System Technology at SITEC Industrietechnologie GmbH, Chemnitz (Hall C2, Stand 553): “The growing market for application-specific laser systems calls for system competence in analysing the technological solution as a whole. The spectrum here extends from the selection of materials, the design of seam geometry and the optical setup through to process design and quality assurance.”
Lasers optimise the production of thin-film sensors
As precise measuring instruments, strain sensors can be used in many ways in automotive engineering and medical technology. To date, they have been manufactured using a template-based structuring technique. The workpieces, which are fully coated with a sensor film, are first structured photolithographically before the resistance elements are synchronised in a further step using laser pulses. Due to the cost-intensive photolithographic process, thin-film pressure and force sensors were suitable in the past more for applications with large batch sizes. Exposure technology also made it necessary to have a smooth surface. However, new laser-based methods now permit a maskless and, thus, cheaper structuring process which extends the range of applications for fatigue-resistant pressure and force sensors. This is possible because surface structuring and subsequent optimisation of surface resistances can be carried out with the same tool, i.e. the ultra-short pulse laser.
Extensive practical and supporting programme
The practical talk entitled “Microtechnical applications of lasers in electronics“ will be held from 10.00 to 12.30 on 25 May 2011 during the Photonics Forum of LASER World of Photonics in Hall C2. Under the direction of Dr. Dietmar Kracht from the Hanover Laser Centre and Dipl.-Ing. Rainer Pätzel from Coherent GmbH, Göttingen, five experts will discuss the potential of laser technologies for microelectronic production. Dr. Christoph Rüttimann (LASAG AG, Thun/Switzerland) and Dipl.-Ing. Winfried Korb (arteos GmbH, Seligenstadt) will talk about the possibilities of the new process for laser beam point welding of copper using an upstream laser pre-pulse module. Dipl.-Phys. Timo Petsch (3D Micromac GmbH, Chemnitz) will give a talk on the advances in short-pulse laser processing of components in micro-electromechanical systems (MEMS) and micro-opto-electromechanical systems (MOEMS).
Dipl.-Ing. Christof Neugebauer (Manz AG, Reutlingen) will talk about the opportunities of laser-based methods for producing lithium-ion batteries and their importance for e-mobility concepts.
Dr. Armin Siber (GFS Gesellschaft für Sensorik mbH, Villingen) will give a talk on the possibilities of ultra-short pulse technology for controlled material removal from sensor films while simultaneously optimising surface resistances
The talks and topics in the Photonics Forums and the entire supporting programme can be called up in the event database at:
For interesting information on the Congress, visit www.photonics-congress.com.
Messe München will also provide the exhibitor database, the entire programme of events and other functions at the start of the trade fair as a mobile application. The “LASER World of PHOTONICS App“ will be available free of charge for iPhones under: www.photonics-app.de. “LASER World of PHOTONICS Mobile“ will be available online for all other smartphones at: www.photonics-mobile.de.