Anthony Yen, vice president of ASML, said recently that they have started developing the next generation of lithography machines. He said that in their company's view, once the existing system reaches its limit, it is necessary for them to continue to promote the development of new generation products, and then push the chip to shrink.
According to reports, the ASML 5000 will have more innovations than the 3400 series that are being used by their customers Samsung, Intel and TSMC. Yen told engineers at the IEEE International Electronic Equipment Conference in San Francisco this week that the most notable was the increase in the machine's numerical aperture from 0.33 to 0.55 today. The numerical aperture is the number of dimensionless quantities and is related to the degree of focus of the light. A larger numerical aperture means higher resolution. Changing the numerical aperture in an EUV machine will require a larger, more perfectly polished imaging lens set.
EUV light is produced by aiming tiny tin droplets using double pulses from a high-power carbon dioxide laser. The first pulse reshapes the tin droplet into a fuzzy wafer shape, so that the second pulse will be more powerful and follow it for only 3 microseconds. It can explode the tin into a plasma and illuminate it with 13.5 nanometers of light. The light is then focused, focused, and popped off the patterned mask so that the pattern will be projected onto the silicon wafer.
By increasing power, ASML has increased the number of wafers that can be processed per hour. Higher power means faster wafer exposure. At 195 watts, they could process 125 wafers per hour; after reaching 246 W at the beginning of this year, that number came to 140 wafers. The company is retrofitting client machines throughout the year with a view to reaching higher standards.
The next generation of machines will require more EUV wattage. In the laboratory, ASML has cracked 410 W, but it has not reached the duty cycle required for chip production. More powerful lasers will help, but this may increase the speed of tin droplets. In today's machines, tin droplets are shot 50,000 times per second, but Yen indicates that the new product's droplet generator may run at 80,000 Hz.
At the same time, the company is improving the capabilities of its 3400 series. The new version 3400C will be released in the second half of 2019, which will increase the efficiency to process more than 170 wafers per hour. But in the development of EUV, one of the biggest pain points is the extremely expensive MASK, which can "keep" the pattern cast on the silicon wafer. This type of covering, called a thin film, protects the mask from stray particles and absorbs too much light. ASML says existing films can transmit 83% of light. This reduces throughput to 116 wafers per hour. Yen said that their goal is to increase the transmission rate to 90%. ASML is also working to keep the inside of the machine cleaner than it is now, so customers can use MASK without film at will.
Yen said ASML expects to ship 18 machines by the end of 2018 and plans to ship 30 in 2019. However, a supplier fire will delay their delivery in 2019, the company said on Tuesday. In August, when GlobalFoundries cancelled 7-nanometer chip development, ASML lost a well-known customer. This move eliminated the need for two EUV machines the company installed in 2017 and 2018, Yen said.