Boosting the technology’s prospects, Peter Wennink, president and CEO of lithography specialist ASML, said: “We have taken new orders for four EUV systems from foundry and memory customers, bringing our backlog to 10 units worth about €1billion. These systems are intended for volume manufacturing sites. We expect to take additional orders in the second half of this year.”
In 2012, Maria Marced, president of TSMC Europe said: “We will continue to use immersion lithography for 20nm but, after that, it will have to be EUV and we expect to have fixed the problems within two years.” But that appears not to have happened.
One of the biggest problems has been the source power. In order to make EUV an economic proposition, wafer throughput needs to be high. Achieving that needs a high power light source. While the target power is 250W, some current development machines are only running at half that power.
Wennink pointed towards positive progress in getting EUV into volume manufacture. “An NXE:3350B EUV system at a customer site [has] processed 1200 wafers per day. We are progressing well toward our 2016 target of 1500 wafers per day, evidenced by the peak performance achieved on a NXE:3350B at ASML of 1488 wafers per day.”
While the industry waits for EUV to get up to speed, equipment manufacturers continue to push the ability to use 193nm immersion lithography, albeit with multiple patterning. Going forward, it appears likely that manufacturers will use a combination of immersion and EUV lithography, with the latter used only to avoid some process steps requiring six or more patterning operations.
