Samsung expands plan to apply pellicle on EUV foundry process

Samsung Electronics has expanded its plan to apply pellicles during the extreme ultraviolet (EUV) process used in wafer fabrication starting in 2023, TheElec has learned.

The company intended to use pellicles for the wafer fabrication of certain high-value chips, but is now planning to apply it to all chips made with the EUV process.

Samsung Foundry, the contract chip product business unit of the company, originally intended to use pellicles for big chips such as CPU and GPU.

The business unit originally intended to apply pellices as “one shot, one die” in its EUV process starting in 2023.

One shot, one die means, during the photolithography process, they would use one mask for one chip. This effectively means that Samsung only intended to use pellicles for chips such as CPU and GPU that are big dies.

Pellicles are very expensive commodities, costing around 90 million won to 100 million won per unit, so Samsung originally intended to use them for big chips first and expand their use later.

But Samsung Foundry president Choi Si-young, after receiving report of the plan, ordered the business unit to expand pellicle use in EUV process to “one shot, six dies”, sources said.

This means one mask will be used to produce six chips on a wafer. This effectively means that pellicles will be used in the production of chips such as microcontroller unit (MCU), which are much smaller than CPU and GPU.

Choi’s orders means that Samsung Foundry intends to use pellicles for all chips that will have EUV process applied during their production, the sources said.

The expanded use of pellicles is to increase the production yield rate. Though pellicles are expensive, if their application can increase yield rate, there is no reason to apply them conservatively to only big chips first, they said. 

Pellicles are used to protect the photo masks used during the photolithography process from dust. Previous ArF exposure equipment shot the light from top to bottom.

But EUV equipment uses mirrors to reflect the light before they reach the wafer.

This causes the light to weaken. To minimize this, pellicles but have over 90% transmittance and be 50-nanometer thin to prevent further light loss. 

EUV masks themselves are also very expensive, so pellicles are needed to protect them.

Samsung has so far not used pellicles in its EUV process despite these risks because there has been no pellicles with over 90% transmittance so far.

The South Korean tech giant is likely to use ASML’s MK4.0 pellicle or their next-generation pellicle in its EUV process starting in 2023.

Samsung’s expanded its use of pellicles in the EUV process will benefit related supplies in South Korea.

FST has developed its own pellicles and pellicles mounter/demounter equipment. S&S Tech is also working on pellicles and EUV blank masks. Device ENG is developing cleaners for EUV photomasks.

Hanyang University professor Ahn Jin-ho, who specializes in EUV, said while Samsung is highly likely to use pellicles from ASML, it could use those from South Korean suppliers together if they can secure the technology to make competence pellicles.