From the viewpoint of consumers, we have been demanding for thinner, lighter smartphones with better performance. Meanwhile, to fabless firms or semiconductor foundries, as we have entered the post-Moore’s-Law era, it is extremely onerous even for professional players of the field, like TSMC or Intel, to design or manufacture chips at smaller fabrication nodes, so as to fulfill the wishes of the mass. As we keep on advancing, traditional lithographic methods such as immersion lithography are no longer applicable. The reason behind is pretty simple – as size of chips is largely reduced, in order to maintain the resolution of lithography, wavelength of light beam used for lithography needs to be simultaneously reduced. Luckily, we have invented technologies to replace methods that we used to adopt, for instance, EUVL.
Extreme Ultra Violet Lithography, or EUVL in short form, is one of the members of the next-generation lithography family. The technology leverages EUV radiation with wavelength of merely 13.5 nm. The high power beams can be both naturally or artificially produced. For nanoscale industries, a source is required to produce EUV radiations. For example, Cymer, a leading UV light source solution provider, utilizes lasers driven by CO2 to produce EUV. Initially, the lasers are directed to a tunnel-like object named beam transport system (BTS). The BTS then sends lasers to a set of focusing lens, which is located in a large box known as the source plasma vessel (SPV), through total internal reflection. At SPV, a device called droplet generator will expel liquified tin droplets with high purity at an astonishing velocity of 70 meters per second and a frequency level of 50000 Hz. Eventually, the brutal collision amid tin atoms and laser beams causes tin atoms to become positive tin ions, which instantaneously produces free electrons. Due to strong polar attractions between free electrons and ions, electrons will accelerate while they are attracted to return to their parent ions, releasing photons with much higher energy. This is how EUV radiations, the beams for EUVL, are produced. The entire process seems to be outrageously complex, yet it literally occurs within a second.
As Cymer has managed to create EUV light sources, ASML, the world’s largest lithography system supplier, purchased Cymer in 2015. The acquisition is plainly synergic to both companies, as they partnered with each other to form one of the strongest alliance in the industry. Collectively, ASML built the first EUVL platform for volume production, namely the TWINSCAN NXE platform. The introduction of the advanced system immediately attracts Intel, Samsung and TSMC, prompting these three dominating semiconductor foundries to purchase and configure the EUVL system, so as to be ahead of the other two major competitors. Due to the lead time required, even though the systems are intended to be used in 2018, the giants have ordered the systems in 2015 or 2016, propelling the robust revenue growth of ASML. As long as the warfare of producing chips of smaller sizes proceeds, the prospect of both ASML and EUVL remains bright. Let’s see how this cutting-edge technology can bring us to a new page in the lithography industry.