Pellicle transmittance reaching over 90%
Samsung will start applying pellicles in the extreme ultraviolet (EUV) process used in advanced chip production starting in 2023, TheElec has learned.
Pellicles, which are used to protect masks from dusts, will be used in mass production starting in late 2023, people familiar with Samsung’s internal plans said.
It is highly likely that the company will use pellicles made by Mitsui Chemicals, a partner of EUV equipment maker ASML, they added.
Argon fluoride exposure machines shot the light from top to bottom. But EUV machines uses mirrors to bend the light before they reach the wafer. Because of this, the light source becomes weaker every time it goes through a mirror. To minimize the effect of this, pellicles need high transmittance as not to weaken the light further before it reaches the wafer. EUV masks costs hundreds of thousands of dollars, so pellicles to protect them from damages is needed.
Despite this, Samsung and TSMC have so far not used pellicles for their EUV processes.
This is because pellicles for EUV processes require over 90% transmittance and must be at least 50-nanometer this, but companies are yet to succeed in securing this specification.
However, companies working on pellicles are now close to over 90% transmittance.
Companies that are developing EUV pellicles include ASML, Mitsui Chemicals, imec, FST and S&S Tech.
Samsung will likely use the pellicle recommended by ASML, the sole manufacturer of EUV equipment. This is because of the tech giant uses non-recommended pellicles, ASML will likely not guarantee after-sales services such as repair. A single unit of EUV equipment costs around 150 billion won to 200 billion won.
ASML had signed a EUV pellicle licensing agreement with Mitsui Chemicals in 2019.
The Netherlands-based fab equipment maker in May also said the pellicle it has co-developed with US’ Teradyne, which as a transmittance of 90.6%, will go into production within the year.
Last year, ASML showcased a pellicle called MK3.0 which had a transmittance of 82% to 83%.
Samsung will very likely use its successor, MK4.0.
Once the South Korean tech giant applies pellicles, its effort to apply more EUV processes to its DRAM production will likely accelerate. Unlike system semiconductors, DRAMs are produced massively, which requires more masks and pellicles.
Besides Samsung, SK Hynix and Micron have also said they plan to apply EUV process to DRAM production. SK Hynix applied the process for its Gen 4 10-nanometer 8Gb LPDDR4 launched this month. Micron is planning to applying EUV process in 2024.