Both Samsung and SK Hynix have achieved it. The pressure of EUV DRAM has come to Micron?
Recently, SK Hynix's official website released news that the company had begun mass production of 8Gb LPDDR4 mobile DRAM products using the fourth-generation 10nm (1a) process in early July. It is worth noting that this is the first time that SK Hynix has adopted EUV technology for DRAM mass production.
SK Hynix defines this progress as having extraordinary significance.
Radical Samsung and SK Hynix
Before talking about whether EUV DRAM is extraordinary, let's first understand some related technologies. In principle, photolithography is a process technology that uses photochemical reaction principles and chemical and physical etching methods to transfer the patterns on the mask to the wafer. For more than half a century, the rapid development of the semiconductor industry is inseparable from photolithography technology.
While the lithography technology is advancing the chip's continuous trend toward high integration and miniaturization, it is also constantly improving. The wavelength of the DUV exposure light source has been refined all the way from 436nm to 193nm. Lithography machine resolution=k1*λ/NA, where k1 is a constant (k1 is different for different lithography machines), λ is the wavelength of the light source, and NA is the numerical aperture of the objective lens. When other parameters are the same, the shorter the wavelength, the higher the resolution, and the more advanced the process. DUV lithography can only achieve 10nm even with dual-machine mode. Now the advanced technology has begun to mass-produce 3nm, which can only be realized by EUV lithography technology. As Samsung said, this is a significant improvement from DUV lithography with a wavelength of 193nm to EUV lithography with a wavelength of 13.5nm. From this, we can see Samsung's attitude towards EUV.
In the DRAM field, Samsung is the first company to announce the progress of EUV DRAM. Thanks to its technological advantages in the field of semiconductor manufacturing, as early as March last year, Samsung announced that the EUV-based first-generation 10nm DRAM (D1x) has completed its customer evaluation, and the first batch of modules delivered reached the order of 1 million. . Just half a year later, Samsung once again released news that its second production line in Pyeongtaek, South Korea, has begun mass production of the industry's first 16Gb LPDDR5 with EUV technology, with a bandwidth of up to 6400Mbps.
Samsung summarized the benefits of using EUV technology to produce DRAM. First, the circuit can be drawn in a smaller and more refined form; second, the mask cost and lithography processing steps can be greatly saved; third, more data can be stored in the same surface area; in addition, the chip energy consumption is even greater People satisfied.
From the perspective of timing and product characteristics, Samsung is indeed more knowledgeable about the mass production of EUV DRAM.
Today, SK Hynix has become the second company in the world to mass-produce LPDDR products using EUV lithography technology. SK Hynix stated that EUV technology was partially used in the previous production of 1y nano-level products, and its stability verification was completed in advance. This mass production ensures the stability of EUV process technology. In the future, 1a nano-level DRAM will be used. The EUV process will be used for production.
After LPDDR4, SK Hynix plans to introduce 1a nano-level technology into DDR5 products from early next year.
The conservative or unique Micron
Statistics show that the current global DRAM market share is mainly controlled by Samsung, SK Hynix, and Micron. With reference to the market share of Q3 in 2020, Samsung accounted for 41.3%, SK Hynix accounted for 28.2%, and Micron accounted for 25%. The three companies together account for nearly 95% of the industry's market share.
While Samsung and SK Hynix have expressed that they have made new progress on EUV DRAM chips, Micron is very slow to EUV lithography technology.
According to foreign media sources, Micron plans to include EUV in its DRAM development roadmap starting in 2024. At the time when both competitors announced mass production of EUV DRAM, Micron's EUV lithography machine was long overdue. In Micron’s 2021 fiscal year’s capital expenditure, part of the cost is to buy EUV equipment from ASML. It is reported that Micron is also accelerating its own EUV process and is recruiting EUV technicians through multiple channels.
Of course, Micron still has its own rhythm and style of play. Judging from the current market news, Micron has realized its own 1α process without the help of EUV lithography technology. In this process, Micron continues to use the 6F2 bit line design, and through improved process technology, compared with the previous generation of the 1z DRAM process, the 1α technology finally increases the memory density by 40%, making the memory solution more energy-efficient and reliable. Mobile platforms that require the best low-power DRAM products bring faster LPDDR5.
Micron believes that this is not a good time to introduce EUV into DRAM. Xu Guojin, vice president of Micron's enterprise and chairman of Micron of Taiwan, China, made it clear last year when Samsung promoted EUV DRAM in full swing that Micron did not intend to follow up.
Micron did this for two reasons. First, Micron believes that DUV DRAM still has great value to be squeezed. It is strong proof that Macron did not use EUV to achieve the 1α process; second, from the perspective of technology maturity and cost, it is not the best time to introduce EUV at this time.
Micron's approach is to "deceive" the Rayleigh Code. Diffraction limits the resolution of the lens. We often use the Rayleigh criterion to characterize the resolution limit of a microscope or telescope system. Micron changes the pattern of the mask to make the light appear sharper. It also includes using water to diffract less light than air, exposing the wafer to water, and replacing the usual air gap between the final lens and the wafer surface with a drop of water. There is also the use of new materials and so on.
After all these efforts, Micron achieved its own 1α process without the help of EUV lithography machines, and its product performance is still in the first echelon.
At present, the three major DRAM manufacturers can be said to be divided into two factions. Samsung and SK Hynix are radicals, striving for EUV lithography technology to exert tremendous energy faster in the DRAM field; Micron is conservative. Even if EUV lithography technology is not adopted, it currently maintains a leading position in cutting-edge DRAM products. level.
However, when the semiconductor manufacturing process is refreshing the minimum number in front of the nm unit time and time again, 10nm is no longer the limit of the DRAM process. The proficiency of EUV technology is likely to become a decisive factor in product competition. The reason for it. Competition is not in the present but in the future.