FEATURE LITHOGRAPHY
one hundred thin layers to promote their reflectivity; some layers are as thin as 3nm. Additionally, as air absorbs EUV light, the whole exposure system, including the wafer, must be integrated into a large vacuum chamber. But the nature of EUV lithography compromises this vacuum, as every time a wafer is exposed, the photoresist releases trillions of particles.
Current state of the industry The past few years have seen a renewed vigour within the EUV lithography market. In 2012, Zeiss shipped its second generation of EUV optics, with a resolution of 18nm at the time, to be integrated into wafer scanners at the facilities of lithography systems manufacturer ASML.
In April 2015, ASML announced that a major chip maker had placed an order for 15 of its production-worthy EUV lithography tools. There are currently eight ASML EUV systems in use in the R&D facilities of its customers, and those customers are now using these machines for process development. ASML customers have also run manufacturing readiness tests on their systems
looking to confirm availability, productivity, and other lithography parameters (such as overlay, focus and CD performance). In one such test carried out recently, a customer exposed more than 15,000 wafers on its NXE:3300B EUV system in the space of four weeks, according to ASML. As productivity is one of the major barriers for moving EUV lithography out of the R&D labs and into mainstream production, this is quite a game changer. The Taiwan Semiconductor Manufacturing Company (TSMC) has also managed to expose more than 1,000 wafers in a 24-hour period using an ASML NXE:3300B EUV system, with a sustained power of more than 90W. This achievement is important, as a sustained average source power of 100W for the EUV laser is considered critical for any commercial production. In ASML’s third-quarter earnings call last month, the company said it expected, in 2016, to ship six to seven EUV tools, which will also be used for process development and device integration work. Production timescales for EUV lithography now seem to be a question of when, not if.
ASML predicts EUV will go into production in 2018/19, and aims to ship its first units in 2017 to meet this target.
Challenges ahead There are still challenges ahead for EUV lithography to reach the Holy Grail of production-ready facilities.
As mentioned, one such challenge is boosting the system’s source power to beyond the 100W range. There are three methods to achieve this: boosting the CO2
laser’s power;
increasing conversion efficiency by optimising the size of the target and increasing peak CO2
power; and reducing dose overhead by using better software controls to increase the available EUV energy for exposure. Trumpf is busy developing the CO2
laser
technology for the EUV source. Dr Michael von Borstel, president and CEO of Trumpf Laser Systems for Semiconductors, said: ‘We are encouraged by positive results published by ASML, in particular on the 2015 EUVL in Maastricht and thereafter. Speaking about the EUV source, dose-controlled EUV power above 180W as demonstrated at ASML is an important breakthrough.’
➤
The next EVOlutionary step for spectrometry
Avaspec EVO series spectrometers will give you: USB 3.0
info@avantes.com |
www.avantes.com Gigabit Ethernet Check out our latest innovations at More memory booth 2311 booth 8739
AVA-002-37_Adv_7x4,425"_Photonics
West_v2.indd 1
05-01-16 12:35
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56