In terms of global foundry market share, Samsung Electronics of South Korea ranks second in market share (about 18%), and TSMC Taiwan Province China Taiwan is the deserved leader (about 55%). In terms of advanced chip foundry below 7nm, TSMC's market share is more than 90%. Its customers include Apple, NVIDIA, AMD, Qualcomm, MediaTek and others. For example, Apple's A17 bionic chip is produced using TSMC's 3nm process. In addition, it is reported that due to Intel's advanced process progress, its 15th generation core may adopt TSMC's 3nm process. TSMC's foundry offer naturally rises, 12-inch 3 nm wafers each offer about $20,000, can be said to ride the dust.

However, South Korea's Samsung Electronics refused to accept this. Jeong Eun-seung, technical director of Samsung Device Solution Division, once said,"Samsung only established the wafer foundry division in 2017, but with the company's expertise in storage manufacturing, surpassing TSMC is just around the corner."

Samsung Electronics Technology takes the lead, but the yield is the main pain point

On June 30,2022, Samsung Electronics officially announced that it began mass production of 3nm chips using the most advanced EUV lithography technology and GAA (Gate-all-around) transistor technology. This also makes Samsung Electronics the first Chinese TSMC to become the world's first mass-produced 3nm chip foundry.

Samsung electronics announced 3nm chip mass production.

According to an official statement released by Samsung Electronics, chips based on its first-generation 3nm GAA process have reduced power consumption by 45%, improved performance by 23%, and reduced area by 16% compared to traditional 5nm process chips.

Samsung Electronics also claims that the second generation of 3 nm GAA manufacturing process is under development, and the next generation process will reduce the power consumption of the chip by 50%, improve the performance by 30% and reduce the area by 35%.

In the second half of 2023, Samsung Electronics began mass production of chips on the P3 line in Pyeongtaek, South Korea. By the end of 2023, Samsung Electronics 'new plant in Tyler, Texas, will be completed. According to Samsung foundry's latest process technology roadmap announced at SFF 2023, the company plans to launch the SF2 process at 2nm in 2025 and the SF1.4 process at 1.4nm in 2027.

However, Samsung Electronics had a lot of controversy on advanced processes such as 3nm, 4nm and 5nm before, and experienced delays in product launch and slow improvement of process yield below 10nm, which led its main customers to turn to TSMC one after another. For example, Qualcomm's first generation of mobile platform Snapdragon 8+ is from Samsung Electronics '4nm foundry to TSMC's 4 nm foundry.

On July 11,2023, Hi Investment Securities researcher Park Sang-woo said in a report: "Samsung Electronics has recently successfully improved the yield of the 4nm process," the report said, Samsung Electronics this year 4nm process yield more than 75%, 3nm process yield more than 60%. Since the second half of this year, the core chips of smart phones, PCs and other equipment have evolved to 3nm. Under the condition that TSMC cannot fully digest 3nm process orders, Samsung Electronics 'yield improvement undoubtedly increases the probability of OEM for Qualcomm, NVIDIA and other companies' chips. In particular, as a comparison, TSMC's 4nm process yield is about 80%, and the 3nm process yield is about 55%.

As a reference, 80% process yield is generally considered to be the watershed for chip foundries to be profitable on a large scale, a reasonable balance between chip performance and manufacturing costs.

There is no doubt that in terms of technological progress, Samsung Electronics of South Korea is not inferior to any competitor, but yield is the main pain point.

EUV thin film is the key to the yield of 7nm and below chips

For nearly 20 years, EUV light sources, EUV masks and EUV resists have been the three major technical challenges of EUV lithography. More than 10 years ago, EUV light sources usually ranked first among the three technical challenges. In recent years, with the continuous progress of EUV light sources, EUV masks have begun to rank first among the three technical challenges. One of the most difficult aspects of EUV masks is the EUV Pellicle.

EUV thin films are high-end consumables in the form of ultra-thin films that need to be replaced regularly, preventing the top layer of the EUV mask while allowing high EUV light transmittance. It is mounted a few millimeters above the photomask surface and protects the EUV mask surface from airborne particles or contaminants during the EUV exposure process. If particles fall on the EUV film, they are not exposed to the wafer because they are out of focus, thus minimizing exposure defects. However, in the EUV lithography process, EUV light passes through the EUV film twice, once incident on the EUV mask and once exiting the EUV projection optical system, which results in the temperature of the EUV film will increase by 6001000 degrees Celsius.

Schematic diagram of EUV masks without (left) and with EUV films

EUV thin films protect extremely expensive 6-inch EUV masks in EUV lithography (a single EUV mask costs more than $300,000) from particles that may fall on its surface. This is especially important for CPU chip production. The reason is that the CPU chip uses a single-die reticle, and any defect in the EUV mask may cause the entire wafer to fail! If a 25-die photomask is used, it results in only a 4% yield reduction for the entire wafer. That is to say, for large-area chips, it is impossible to protect them without EUV film. For small area chips, it may be feasible to have no EUV film protection.

Harry Levinson, Head of Lithography at HJL, said: "Trying to do EUV lithography without EUV thin films is painful. This requires more testing and still has the potential to result in lost production."

EUV mask

Technical Challenges and Development of EUV Thin Films

Joost Bekaert, a researcher at IMEC, Europe's microelectronics "brain," said: "Very few materials have a high EUV transmittance of more than 90% while withstanding EUV light radiation of more than 600W. In addition, the thin film needs to be robust to prevent it from falling on a large area (about 110mm x 140mm) EUV mask." Specifically, EUV thin films must meet the following stringent criteria:

The thickness is only tens of nm (usually 20-30nm), and the large size film corresponds to an area of 110 mm×140 mm.

In order not to affect the process yield, the transmittance should at least exceed 90%, and the unevenness (3σ) ≤0.4%;

withstand EUV radiation with power densities up to 5W/cm² (corresponding to an EUV power of 400 W);

Strong mechanical properties, maximum acceleration of 100 m/ s²(corresponding to the film moving speed on the mask stage of EUV lithography machine), Young's modulus exceeding 1 TPa;

Maximum environmental pressure change resistance 3.5 mbar/s;

Reflectivity 0.005%,"zero defects". Endurance of extreme harsh operating environment: 1000°C high temperature, multiple outgassing, pumping process, the film does not appear any cracks or fractures.

Lithographers have experienced a long and tortuous process in the development of EUV thin films. The main reason is that most materials have strong absorption in the EUV band. Polysilicon, silicon nitride, carbon nanotubes and graphene have been explored, and there have been many debates about whether EUV lithography must use EUV thin films.

The earliest developer of EUV thin film was ASML Company. After hard work, ASML successfully developed polysilicon EUV thin film with an area of 106 mm×139 mm in 2014, but its thickness is 70nm, and the highest EUV transmittance is 86%. In 2019, the thickness of the polysilicon EUV film was 50nm, and the highest EUV transmittance was 88%.

Polysilicon EUV Thin Films Developed by ASML

In 2019, ASML launched its first commercial EUV thin film and licensed the technology to Mitsui Chemicals of Japan, which began mass sales in the second quarter of 2021. At this point, the debate over whether EUV lithography must use EUV thin films is over.

Commercial Polysilicon EUV Thin Films

IMEC has also been conducting research on EUV thin films. Unlike ASML's technical route, IMEC uses carbon nanotubes with an EUV transmittance of 97.7%! It can increase production efficiency by about 25%.

Carbon nanotube EUV thin films

A Finnish company, Canatu, is commercializing carbon nanotube EUV thin films. Canatu originated from the Nanomaterials Laboratory of Aalto University in Finland. Since 2010, Canatu has been working on carbon nanotube EUV films and improving manufacturing processes. More than 150 patents have been granted covering 25 categories. Canatu established its first production line for carbon nanotubes in 2015, working with IMEC to develop carbon nanotube based EUV thin films.

Next, the graphene EUV thin film appeared.

Graphene under Nobel Prize halo

The 2010 Nobel Prize in Physics was awarded to Andre Geim and Konstantin Novoselov of the University of Manchester for their work on graphene. The award was awarded "for groundbreaking experiments regarding the two-dimensional material grapheme."

the 2010 Nobel Prize in Physics

According to Nobel's website, Andrei Geim was born in Sotji, Russia, in 1958 to a family of German descent. He lived with his grandparents for the first seven years. It wasn't until later that Geim discovered that both his grandfather and father were physicists who had spent years in labor camps. After receiving his Ph.D. in physics from the Russian Academy of Sciences in Chernogorovka, Geim worked at several European universities, including Nijmegen in the Netherlands. Gem has worked at the University of Manchester in England since 2001.

Before graphene was discovered, Andre Geim won the Ig Nobel Prize in 2000 for his Flying Frog project, which uses magnetic levitation technology to overcome gravity and levitate a frog in midair. On the day of the awards, Andre Gaime received the award live. This experiment has also been named one of the ten most popular achievements of the "Ig Nobel Prize" for 18 years. Now, this principle is also included in physics textbooks of some foreign universities.

Konstantin Novoselov was born in Nezhnetagir, Russia, in 1974. After studying in Moscow, he studied for his doctorate under the supervision of his mentor, Andrei Geim, first at Radboud University in Nijmegen, the Netherlands, and then at Manchester University in England.

two-dimensional material graphene

According to the Nobel website, carbon exists in several different natural forms. A material with carbon atoms arranged in a hexagonal lattice and only one atom thick has long been thought to have a purely theoretical structure. In 2004 Konstantin Novoselov and Andrei Geim succeeded in making this material graphene and charted its properties: very thin but still very strong, with good thermal and electrical conductivity, almost completely transparent but very dense. Graphene opens up new possibilities in materials technology and electronics.

Graphene materials paper published in Science in October 2004

Graphene is a new material in which carbon atoms connected by sp² hybridization are closely packed into a single-layer two-dimensional honeycomb lattice structure. It is currently the thinnest material in the world, with a thickness of 0.335 nm. Konstantin Novoselov and Andrei Geim's method of preparing graphene is simple, using mechanical exfoliation, which is technically defined as a method of separating graphene or graphene nanosheets from graphite crystals by applying mechanical forces (friction, tension, etc.) through graphite crystals. Simply put, a sheet of graphite is taped off, and the sheet still contains many layers of graphene. But after ten or twenty times, the flakes get thinner and thinner, eventually producing some graphene monolayers.

So far, many laboratory studies of graphene have used mechanical exfoliation methods. Obviously, this method has low controllability, it is difficult to realize large-scale synthesis, and it cannot be industrialized. Therefore, some people jokingly called this "explosive prize for tearing tape paper".

Graphene has many amazing properties. Specifically:

1) mechanical strength, not easy to be destroyed, 300 times stronger than steel;

2) good tensile performance, it can stretch to 20% of its own length, more than 1TPa, because of its hexagonal structure, stretching will deform, but will not be destroyed;

3) As a non-metallic material, it is better than the metal silver with the best conductivity at present, reaching the conductivity of 106S/m.

4) The material with the best thermal conductivity in nature is silver. Graphene has a thermal conductivity coefficient of 5000W/(m·k), which is 10 times stronger than silver. Interface thermal resistance 1 mm²K/W

5) High electron mobility 10000cm²/vs, even 20000cm²/vs

6) Ultra-thin, large specific surface area, but also transparent, curved.

Graphene has been called "the material that changed the 21st century,""the king of materials," and so on.

graphene-based super fast-charging battery

Can graphene EUV thin films be the first to be commercialized?

TSMC attaches great importance to EUV mask technology. On the one hand, the company invented an "EUV mask dry cleaning technology". Unlike traditional wet cleaning processes that use ultrapure water and chemicals, this dry cleaning technology can quickly remove contaminants and significantly reduce contaminants by accurately locating the source of contamination through sub-nano analysis techniques. On the other hand, since 2019, TSMC has been using its own EUV thin film on its production line, and in 2021, its EUV thin film production capacity has increased by 20 times compared with 2019.

Dr. Kevin Zhang, Senior Vice President of Business Development at TSMC, declared: "We have obviously invested internally in this area, and I think it is a very unique technology for us. We were able to use it to achieve our EUV mass production. If you look at the way we run at 7 nm, 6 nm and now 5 nm, all of which use EUV, obviously we've made tremendous progress. So that's definitely an area where we think we do well with our unique technological edge."

TSMC EU President Dr Maria Marced declared: "One thing, because I am in Amsterdam, we are closer to ASML-we have received their special training. I can tell you that doing this kind of production in-house really allows us to extend the lifetime of optical masks. Usually in EUV lithography, masks get dirty, so this really helps us to improve the productivity of EUV lithography and masks in a short period of time."

Samsung Electronics is also clearly aware of the importance of EUV thin films in improving EUV lithography yield, and has been actively developing and evaluating EUV thin films made of carbon nanotubes and graphene, aiming to develop graphene thin films that meet 92% EUV transmittance to narrow its market share gap with foundry competitor TSMC. At the Samsung Foundry Forum held in October 2021, he said: "We have developed a thin film with an EUV transmittance of 82% and plan to increase the transmittance to 88% by the end of the year." Samsung Electronics is developing its own graphene EUV thin film mass production facility.

"Samsung Electronics is pushing the development of EUV thin films to quickly catch up with TSMC, the No. 1 foundry company," one analyst said. Although Samsung Electronics has improved thin film technology, it has not yet introduced the material into its dynamic random access memory (DRAM) production line and believes it is too early to apply the material to large-scale production lines.

In addition to developing its own EUV thin film, Samsung Electronics is advancing cooperation with major domestic materials companies S S TECH and FST (FINE SEMITECH). Samsung Electronics has invested in S S TECH and FST to ensure the development of graphene EUV thin films with an EUV transmittance of 90%.

Korea Graphene Plaza Co., Ltd. is a pioneer in the commercialization of graphene EUV thin films. The company was incubated by the laboratory of Kwon Yong-deok, a chemistry professor at Seoul National University, and was established in 2012. The company has claimed to have developed graphene EUV thin films for EUV lithography of chips of 5nm and below, and is preparing for an initial public offering. Kwon Yong-deok said: "Previously, thin films were made of silicon. But we use graphene. Graphene thin films will improve yields for semiconductor companies using ASML EUV lithography equipment."

The company's large-area graphene EUV film is synthesized using a dedicated chemical vapor deposition (CVD) method using carbon dioxide and copper catalyst substrates at high temperatures. The Israel Institute of Technology purchased three of the company's graphene synthesis and production facilities.

Kwon Yong-deok said: "Simply put, our CVD technology adheres polymer compounds to copper synthesized graphene, then uses an etchant to remove copper, and finally separates graphene from molecular compounds."

Graphene EUV thin film manufacturing process

An EUV thin film costs about $75,000 (protected EUV masks cost about $35.75 million). If you operate manually during the operation, errors may occur. To this end, FST has developed the "world's first" EUV Pellicle mounter Demounter to automatically mount and remove EUV films on EUV masks. FST has also developed an EUV thin film inspection system using laser and image processing technology to inspect EUV thin films and their frames for foreign matter. It can also automatically analyze and view foreign objects, identify the location and characteristics of foreign objects.

Choi Sung-won, Director of Research at FST, said: "With the development of this device family, we have laid the foundation for becoming an EUV Total Solutions company. The series is a world number one and Korea number one; it makes sense for their value to be accepted by our customers."

EUV thin film mounting/dismounting equipment

Kim Byung-kook, a former Samsung Electronics employee, founded startup EUV Solution in January 2018, which has developed EPTR, an equipment for detecting the transmittance of EUV thin films. EPTR uses EUV wavelengths to measure the transmittance and reflectivity of direct EUV thin films at ultra-high speeds. EPTR has been installed in a customer company and officially put into use. Li Donggen, vice president of EUV Solution, said: "The transmittance of EUV thin films directly affects the engineering yield, so the process of accurately measuring transmittance becomes more and more important. Customers using EPTR can develop and measure EUV thin films more smoothly. When the product is out of stock, it can be directly indicated with specification information.

EUV mask with graphene EUV film.

A Few Views on Graphene EUV Thin Films

1. Since 2004, two-dimensional materials such as graphene have been frequent visitors to top magazines such as Science and Nature. Graphene is the thinnest, lightest and strongest material known in the world. It has unique structural characteristics and physical and chemical properties. Its unique structural characteristics endow graphene with excellent physical, chemical, optical, electronic and magnetic properties different from bulk, zero-dimensional and one-dimensional materials. From a scientific point of view, graphene work won the Nobel Prize, and the controversy was very small.
2. Nobel Prize evaluation is a major contribution to human exploration of the laws of nature, commercialization follows the logic of whether to make money. Although graphene has broad application scenarios in the fields of chips, materials science, optoelectronics, catalysis, micro-nano processing, new energy, biomedicine, sensors, aerospace, biomedicine, drug delivery, etc. For example, as a high electron mobility material can be used for chips; as an excellent transparent conductive film can be used for touch screens; as a lightweight and high-strength material can be used for spacecraft; as an excellent conductive material can be used for masks and other daily necessities; as an excellent electrical material can be used for batteries; and so on. However, none of them have been commercialized.
3. At present, the field closest to commercialization of graphene should be EUV thin films. Once commercialized successfully, it will play a crucial role in improving the production efficiency and yield of EUV lithography, thus greatly improving the yield of chips below 3nm.
4. The main difficulty of graphene application in EUV thin film is how to prepare wafer-level, controllable layer number, self-supporting and highly uniform graphene EUV thin film by microwave plasma chemical vapor deposition. Including the development of special deposition equipment, graphene EUV film preparation process, graphene EUV film transmittance and other parameters of the test, graphene EUV film installation; and so on.

There is no doubt that Korean manufacturers occupy a very advantageous position in the commercialization of graphene EUV thin films.

This article comes from Weixin Official Accounts"Semiconductor Industry Observation"(ID: icbank), author: Yiping Yifan, 36 krypton is authorized to publish.