It weighs as much as two Airbus A320s and consists of more than 100,000 parts, 3,000 cables, 40,000 bolts and more than 2 km of electrical connections. TWINSCAN EXE: 5000 photolithography equipment designed and manufactured by ASML is an integrated circuit manufacturing machine the most difficult thing there is. And also the most expensive. The most recent information we have indicates that one of these devices costs €350 million, which will surely make some chip makers think twice before purchasing one.
Currently, only one of these machines is in the testing phase, and Intel has kept it at its Hillsborough (USA) plant since the end of December last year. ASML engineers have spent ten years developing the technology required to develop this machine, which is actually a second-generation ultraviolet (EUV) lithography machine. This company from the Netherlands plans to deliver about 20 devices of this type to its customers every year starting in 2025 with one goal: to enable them to produce 2nm chips and beyond.
UVE High-NA lithography equipment is one of the most sophisticated machines in existence
For the development of high-aperture ultraviolet lithography equipment (EUV High-NA (abbreviation in English), to which we deservingly dedicate this article, ASML engineers have developed a very advanced optical architecture that It has an aperture of 0.55 compared to the value of 0.33 that first-generation UVE lithography equipment has. This improvement in optics allows higher resolution patterns to be transferred to the wafer, making it possible to manufacture chips using more advanced integration technologies than those currently used in 3nm nodes.
The sophisticated optical architecture of the high-aperture UV equipment allows higher resolution images to be transferred to the plate
In the article we devoted to the Rayleigh criterion, we explain in great detail what the “NA” parameter consists of (numerical aperture), but in this text it is enough for us to know that this variable determines the aperture value of the optics used by the lithographic equipment. In this context, this parameter essentially reflects the same as the aperture value when we talk about the optics of the camera, so it determines the amount of light that the optical elements are able to collect. As we can guess, the more light they collect, the better.
However, that is not all. ASML has also improved the mechanical systems responsible for processing the wafers to make it possible to produce a single high aperture UVE machine more than 200 wafers per hour. The photos that illustrate this article allow us to feel the extreme complexity and sophistication of one of these devices, which, by the way, would not be possible without the cooperation of other companies, such as the German ZEISS or Cymer, a company of American origin, which is currently well established in ASML structures.
In a way, this latest company provides ASML with the raw materials it needs for photolithography machines. And this raw material is none other than ultraviolet light, which is responsible for transporting the geometric pattern described by the mask so that it can be transferred with great precision to the surface of the silicon wafer. The light used by high-aperture equipment belongs to the most energetic part of the ultraviolet range of the electromagnetic spectrum. In fact, its wavelength ranges from 10 to 100 nanometers (nm).
The problem is that generating and dealing with this form of electromagnetic radiation is not easy. And it doesn’t, among other reasons, because it’s so energetic that it changes the structure of the physical elements it interacts with inside the lithography machine. Additionally, the EUV light must travel from the source to the silicon wafer without interacting with the smallest particle of dusttherefore, it is essential that the entire chip manufacturing process be carried out inside a chamber designed to provide a high-quality vacuum.
The photo below shows one of the anamorphic optical elements used in ASML’s high-aperture UV lithography machines during testing at the ZEISS lab. Their role is very important because they are responsible for transmitting the ultraviolet light with a wavelength of 13.5 nm from the source responsible for its emission to the mask containing the geometric pattern to be recorded on the silicon wafer. From this moment, the projection optics comes into action in order to transmit ultraviolet radiation, which already contains a geometric pattern, to a plate made of semiconductor material.
This is a very complicated process. If the mirrors involved in the propagation of ultraviolet light are not manufactured with great precision, the geometric pattern defined by the mask will be changed and the chips will go to waste. In addition, the reflective mirrors, which are responsible for transporting the light from the radiation source to the mask, must ensure that Ultraviolet radiation reaches the latter with remarkable uniformity. Otherwise, again, the IC manufacturing process will not be successful.
In addition, the mirrors used in high-aperture equipment are larger than those used in conventional UV machines, making their production even more difficult. Of course, as we have seen in this article, every high-aperture UVE photolithography equipment is a true engineering prodigy.
Images | ASML
Additional information | ASML
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