Current status of EUV lithography

It is undeniable that extreme ultra-violet lithography has progressed in an extraordinary way in the last 12 months.

Until recently, it was not commonly agreed upon in the lithography industry whether EUV litho would have made it to full production or HVM (high-volume manufacturing) at all.

Naysayers were pointing to the fact that the power of the light source was lagging much behind the level needed for HVM and that the issues in mask defectivity control and in resist development were far from being addressed properly.

Fortunately enough, in the last 12 months huge progress has been made in most if not all areas of EUV litho:

1. Light source development

Most of EUV pundits believe that light source power is the single most important issue for successful EUV lithography development and most resource investment related to EUCV has been focused in achieving a light source powerful enough to sustain high-volume manufacturing requirements.

Only one year ago, TSMC was having problems in breaking the 10W barrier while now the same company made public their results and claimed they were able to achieve an impressive 1000 wafers processed in a single day with a 80W source.

The two major companies behind EUV light source development, Cymer and Gigaphoton, are both claiming to be on track to achieve a 125W power source by the end of this year with a 250W light source on the horizon for next year.

Cymer claims to have a 100W power source running in their labs with 3.5% conversion efficiency and based on a 15KW laser which they hope to be able to upgrade to 5.5% conversion efficiency using a 27KW laser by next year at latest, which would mean 250W of light source power, well enough for high volume manufacturing

Gigaphoton, on the other hand, recently issued a press release announcing to have a light-source running at 142W with 50% duty cycle (=71W at 100% duty cycle), a significant improvement from last December when they claimed to have a 120W working at 50% duty cycle. Gigaphoton made clear that they are now looking for achieving 250W in “burst mode” before being able to expand the source availability.

While neither Gigaphoton nor Cymer have any plans for light sources beyond the 500W mark, Free Electron Lasers are now being considered by other players as a viable route to step into the 500W~10000W range which is what will be needed for high-NA scanner machines.

2. High-NA scanners

Carl Zeiss is currently working on improving the optics quality and based on this, ASML is now hoping to be able to achieve numerical aperture (NA) of 0.5 up from the current mark of 0.33 which would allow to reach a couple of nodes beyond 10nm without the need of multiple patterning using EUV.

3. Resists

Resist development has been an issue mostly disregarded by EUV pundits until recently as all the attention went to what was considered as the major hurdle for full development of EUV litho, that is, the availability of a light source powerful enough for HVM.

Since now the problems with light source development seem to be on track to be solved, attention is back to other aspects of EUV litho development such as resist.

Due to strict requirements it takes quite some time, even 1~3 years at least, to have a resist validated for full production so it has now become imperative to address this issue as well.

Much of the recent work is now behind negative-tone CAR resists, while Intel is working with resist makers on HfO2-based resists trying to improve their shelf-life from the current range of few weeks to a few months or more.

The advantage of metal oxide-based resists is that they have high absorption properties and therefore they can allow the use of light sources with lower power.

Other areas of development where control in EUV mask defectivity, with Hoya showing promising results in reducing the mask blank defects, and mask defect inspection, with Carl Zeiss announcing their upcoming tool specifically targeted at EUV mask inspection by the end of this year .

Gigaphoton’s EUV Light Source Advances to 92 Watts Output at 4.5 CE

Gigaphoton Inc. has recently announced that they were able to produce a light output for extreme ultraviolet (EUV) lithography scanners with more than twice of the amount they had three months ago. From the 43 watts at 2.4 conversion efficiency (CE) reported output last February, their prototype laser-produced plasma (LPP) is now emitting light at 92 watts with 4.5 CE.

As one of the main manufacturers in lithography light sources, Gigaphoton has committed to continuously explore the EUV light sources until its output is ample for mass-production. Because of the low output power of the light sources used in EUV systems, wafer exposure takes longer time to complete, which results to throughput insufficiency for high-volume manufacturing (HVM). To demonstrate it with an actual manufacturing data,  a 70 watts light output can only produce 52 wafers per hour. With 92 watts, on the other hand,  Gigaphoton estimated that the throughput will increase to 60 wafers per hour. By the end of 2014, Gigaphoton aims to produce as much as 150 watts and eventually push it further until it reaches the minimum considered output for HVM, which is  250 watts.

Hitoshi Tomaru, Gigaphoton’s president and CEO, said that their achievement of 92 watt output with their light sources is a fruit of the steady, yet unique, R&D efforts to achieve development of higher output, stable, and lower cost of ownership [on] LPP light sources. He also believes that their expertise and efforts to develop LPP light source that accelerates the development of EUV scanners for HVM will encourage the industry to introduce the EUV scanners as the next-generation lithography tools.

The big leap in the energy output of Gigaphoton’s LPP prototype can be attirbuted to the optimized lasers, which radites small tin droplets of diameter less than 20 micrometer with solid state, pre-pulser laser (Yag laser) and high power CO2 laser.  The Yag  laser breaks up the tin droplets into smaller fragments, which when once spread at a sufficient diameter is theexposed on the CO2 laser. The electrons of the plasma radiate with the tin ions, emitting photons of a desired wavelength of 13.5 nanometers. To optimize the performance of the collector mirror, the unwanted tin debris of the radiation are removed by a high output, super conducting magnet and tin etching.

Gigaphoton is a wholly owned subsidiary of Komatsu Ltd. Their EUV light source reasearch and development is a program subsidized by New Energy and Industrial Technology Development Organization (NEDO). Gigaphoton’s innovative efforts on LPP EUV technology and other laser technologies has paved the way to cost effective and productive lithography light sources.  They have been working aggressively on EUV lithography with the obejctive of surpassing the era of ArF lithography.

Note:
If you are interested in our services, please visit our site.

Subscribe to our newsletter to receive our new articles directly in your mail box.

If you liked this article, please give it a quick review in StumbleUpon, Facebook or Pinterest.

The long (and unfinished) story of EUV technology

EUV lithography

There are times in life when you understand that you are not so young anymore.

To me, it happens when I think about EUV technology.

I still remember very well when EUV was started to be heralded like the next generation breakthrough technology for lithography steppers.

I was an avid technology reader at the time and I first heard about EUV around 1995 or 1996, if I remember well.

Few years later, I remember the first discussions about when EUV would have been ready for production, I remember few analysts claiming EUV would have been ready for the 65nm node.

Well, this would have meant to have a production-ready tool by 2005.

Needless, to say, EUV never made it for an insertion at the 65nm node, then skipped the 45nm node as well, the 32nm node, the 22nm, the 16nm and now ASML is talking about alate insertion at the 10nm node, but most analysts are skeptical that the technology will be ready on time

I remember that few years after I started to hear talks about EUV, another technology was coming out as the most promising NGL (next generation lithography) candidate: 157nm.
157nm lithography was in some ways less revolutionary than EUV, it was the logical step in the traditional evolution of lithography, from using 248nm wavelengths lasers, to 193nm finally to 157nm

157nm lithography actually never made it into production as alternatives like immersion and multi-patterning lithography became mainstream.

So what about EUV?

EUB is still in the game, so much in the game that recently Intel has invested some $2.1billion in ASML and in return ASML has bought Cymer, a light-source maker specialized in light-sources for EUV.

At a party at the Belgian Embassy here in Tokyo, after the annual conference of IMEC at the New Otani Hotel, I approached a senior researcher from IMEC and asked why, despite the numerous delays of EUV, still the major players in the industry were pouring billions in this yet to be completely proven technology.

His answer was plain and honest: There are no other options

And his comment proved to be true: all the technologies that were hoped to become a potential replacement in case of EUV failure become players in other markets or simply disappeared.

Multiple beam E-beam technology, proposed by Mapper who got funded by TSMC, was assumed to become a player at the end of last decade but the hopes failed to materialize.
Nanoimprint technology is alive, kicking and growing, but not for IC manufacturing (despite Molecular Imprints` s claims to have a soon-to-be-ready IC-patterning capable tool). The technology has found a vast interest in the bio, film-replica and other markets.

Multiple patterning and immersion lithography have been heavily used to extend the life of conventional 193nm lithography so far, but costs are increasing exponentially at every node, and multiple patterning, once a synonymous of double-patterning, is now meaning triple, quadruple or even quintuple-patterning.

Direct self-assembly is promising, but still very much at the R&D level.
So what is left?
Not much, I would say.
Despite the claims of Peter Wennink, the new CEO of ASML, that EUV will, finally, be production-ready soon, we come to know that the technology will reach improved standards only by 2017, this is, definitely late for the 10n node and possibly late for the 7nm node.

While I do believe that EUV may be ready for mass-production before the end of the decade, the main issue would be if EUV will be ever seen as the savior of Moore` s Law or if, instead, will be relegated as a complementary technology with the mainstream production ecosystem moving to alternative solutions like 3-D stacking, for example.

Note:
If you are interested in our services, please visit our site.

Subscribe to our newsletter to receive our new articles directly in your mail box.

If you liked this article, please give it a quick review in StumbleUpon, Facebook or Pinterest.

Gigaphoton making progress with both EUV and 450mm-wafer lithography technology

EUV

Gigaphoton, a major lithography source maker based in Japan, is currently making stable but sustained progress in two different areas of the lithography market: 450mm-wafer litho and EUV (extreme ultra violet lithography).

In the quest led by ASML towards a stable, high-power EUV lithography system, Gigaphoton has moved away from the traditional approach led by Cymer and explored an original technology: laser-produced plasma (LPP). Working since 2002 on this field, the Oyama, Japan-based company had now achieved a 43W light output which represents another milestone in pursue of the 250W EUV light source that is necessary for having a high-volume manufacturing-ready stepper machine.

Light-source power is now deemed by many analysts as the number-one issue preventing EUV lithography from reaching mass adoption

Cymer now claims to have a 105W light-source soon ready, but the traditional approach pursued by the American manufacturer, recently acquired by ASML, is taking more time than expected.

Gigaphoton is hoping that their approach to light sources for HWM-steppers can be quicker and give more robust results.

Despite their inferior power output in comparison with Cymer, Gigaphoton expects their LPP technology to scale faster and expect to be able to reach a 250W output in a couple of years.

LPP light source generate EUV light by irradiating tin droplets using a solid-state laser and then using a main CO2 laser as the main source.

Among the various technical issues that the company has been facing, the main one has probably been debris mitigation, which has been partially solved with the use of superconducting magnets.

The Japanese company has however made lots of strides in another field: 450-mm wafer lithography technology

450mm wafers are not expected to become mainstream in the semiconductor industry at least until 2017-2018, and there are many analysts that suggest that the move from 300mm to 450mm-wafers may not happen at all.

However, the big names in the semiconductor industry (Intel, TSMC, IBM among others), are investing heavily to promote the technology and instituted the Global 450C consortium based in Albany, NY, fully dedicated at the development of all the ecosystem needed to create a successful transition in the industry from 300mm- to 450mm- wafer lithography, including all the wafer-testing process, the prototyping and R&D phase and the high-volume equipment

450mm-wafer lithography is still in its infancy, and the ArF lasers required for the first steppers require a highly stable, energy profile with a greatly improved overlay accuracy
Gigaphoton, who has collaborated with G450C since the very beginning, has recently announced that their ArF laser will be used for the first G450C immersion lithography steppers. Gigaphoton is now striving to become the number one light source provider.

While adoption of EUV for 450mm-wafers is forecasted to happen not before the end of this decade at the earliest, it is clear that Gigaphoton is now one or the only company who can play a relevant role in both technologies for the light-source part.

Hitoshi Tomaru, President and CEO of Gigaphoton, said that œwe are all very excited to be part of the ground-braking work done at G450C. We [Gigaphoton] are fully committed to offer products and continue to invest to achieve the best results in the research and development of high-quality advanced lithography systems.

Note:
If you are interested in nanoimprint lithography, please visit our nanoimprint lithography service page.

Subscribe to our newsletter to receive our new articles directly in your mail box.

If you liked this article, please give it a quick review in StumbleUpon, Facebook or Pinterest.