By Vivek Bakshi, EUV Litho, Inc.

For a better understanding of EUVL’s status, challenges and opportunities, it is important to study its fundamental components. There are several, with the main ones being source, mask, optics, imaging and resists. They are very different from those in the current 193 nm immersion lithography, and a comprehensive overview of these components is a must. Hence, in the annual EUVL Workshop we dedicate one full day to a study of fundamentals with experts. Here I will tell you briefly about them.

EUVL is basically an optical projection lithography, but with many twists. The main reason for this is the 14x decrease of wavelength to gain on resolution, while previous reductions have been much smaller, like 1.5x. This steep decrease in wavelength requires us to work in a new region of physical properties of materials, in greater depth than we have done before.

The EUV light source is the most complex part of EUVL, and it took the most effort and time to develop. This technical feat is truly doing “rocket science” in the fab. This source was a potential showstopper at one time and now it is the key enabler for EUV for today, and for future extensions. Times have changed! For scanners, we use tin based laser produced plasma sources, but for metrology many other types of EUV sources are used and few others being considered. We will discuss technology, challenges and potential of these sources and their metrology.

Inside the EUVL scanner we use mirrors instead of the lenses used in 193 nm scanners. EUV optics, once considered impossible to manufacture, today is ahead of the curve in needed performance. But there is always more work to be done to get ready for the next nodes. EUV optics and optics chain design in an EUV scanner add unique properties to EUVL patterning. Just like optics, EUV mask is also made of multilayer mirrors with several additional levels of complexity – off-axis illumination and 3-D effects to name two. We are also learning to deal with mask defects, cleaning, defect detection and now pellicles.

Patterning with EUV involves dealing with 3-D effects, flare, new illumination and unique EUV specific optics designs. It now works like a charm, but lots of effort has gone into it to. Today, a lot more work currently is being done to extend patterning to smaller nodes with higher numerical aperture (NA) scanners. EUV resists with more energetic photons have a different chemistry and patterning performance. This is making us look beyond traditional chemically amplified (CAR) resists into new chemistries and do additional fundamental research.

Another important question for many small and large, new and established suppliers for various components for chip-making, especially who arrived late to the game, is where their products, supply chains and competencies fit in the EUVL food chain. Getting to know the fundamentals and overview of EUVL status and challenges will make the picture clearer for all. As all components interact with each other, people working in one area of EUVL with benefit immensely with an overview of other areas as well. We hope that a day of going over the EUVL basics will be very worthwhile for those who climb the hill of Berkeley this year to attend the EUVL Workshop. Additional information about this EUVL short course is available at www.euvlitho.com

By Vivek Bakshi, EUV Litho, Inc.

Latest news on EUVL technology status is a topic of much interest to community involved in making high‑end next generation computer chips. Next month, we will have the leading EUVL suppliers, chipmakers and researchers in Berkeley giving us the updates on short- and long-term focus areas for EUVL. I would like to summarize what I expect to be the highlights and their significance for us.

Focus on EUVL is on two fronts. First is progress in the short-term focus area that will decide how quickly, as well as how effectively (throughput and cost of ownership or COO) EUVL is being used in fabs. Topics in this category are source availability (which relates to cost of ownership), pellicles and patterning status.

We will have a manufacturing update from ASML, GlobalFoundries and Intel on these topics in their keynote and invited talks. Gigaphoton (GP), 2nd supplier of EUV sources for scanners, will talk about their new collector design with a longer lifetime (hoping for a better COO). Inpria and JSR will provide updates on the progress of EUV resists. An invited talk from IMEC will give the latest on patterning performance of EUVL from their fabs – where they are working with leading chipmakers and suppliers to prepare EUVL for manufacturing.

The second topic relates to longer term progress, as EUVL is a multi-node patterning technology expected to take us to the end of Moore’s Law. Top topics are higher NA (0.55) EUVL scanner, pathways to increase power closer to 500 W and even higher, actinic patterned mask inspection (APMI) and resist performance (stochastics, LER, micro-bridging, etc.). We will have invited talks from ASML and Zeiss on optics and design of high NA scanners. Both ASML and Gigaphoton will talk about their power scaling plans, together with several papers on EUV source fundamentals needed to ensure scaling.

I am excited about the new free-electron laser (FEL) based technology from Lyncean that they claim can provide standalone 1 kW EUV Source, based on FEL. KEK from Japan is also going to report on the progress on their FEL based EUV source technology. As APMI tools using conventional EUV sources have not been ready, the focus has moved to HHG based EUV sources for enabling mask defect inspection. These tools use alternative imaging and processing techniques, which will be described in several papers. There will be a keynote talk from Prof. Margaret Murnane, whose company has been a leading supplier of HHG sources and now plans for its increasing use in the support of lithography, including mask inspection. Veeco, maker of EUV mask blank deposition tool, used by all mask blank makers, will report on the progress of their technology to further reduce mask blank defects. There also will be several papers on resist fundamentals, which is a key knowledge enabling EUV resist readiness for future nodes.

Like previous years, we expect to hear good discussions and to generate new ideas. We plan to deliver lots of new information in just two days (over 40 papers including a poster session, which is more than many other larger conferences) in a more personal and informal setting. The workshop is from June 12-15, 2017 at CXRO in Berkeley, CA. More information is at www.euvlitho.com.

A final note: I believe that for better understanding of EUVL – status, challenges and opportunities – it is important to study its fundamental components. There are several components (source, mask, optics, imaging and resists) and they are different than current immersion lithography. At least a comprehensive overview of these components is a must. Hence, in the EUVL Workshop we dedicate one full day to study of fundamentals with experts. So please look for my next blog, “Understanding EUVL Basic and Status – Top Key Concepts,” at this site for further details.