SK Hynix Considers 4F2 or 3D DRAM Amid Rising EUV Lithography Costs

According to a report from Korean media outlet THE ELEC, SK Hynix researcher Seo Jae-Wook, speaking at an academic conference in Suwon, South Korea, on August 12, stated that the company is considering a shift to 4F2 or 3D structured DRAM memory to alleviate the increasing cost pressures associated with EUV (Extreme Ultraviolet) lithography.

Seo Jae-Wook noted that starting with 1c DRAM, the costs associated with EUV lithography have escalated rapidly, prompting the need to evaluate whether continuing with this manufacturing method remains profitable.

In light of these challenges, SK Hynix is also exploring the possibility of transitioning to Vertical Gate (VG) or 3D DRAM for its next-generation products. The VG DRAM referred to by Seo Jae-Wook is also known as 4F2 DRAM, which Samsung Electronics markets as VCT (Vertical Channel Transistor) DRAM. This type of memory features a vertically constructed cell structure.

The 4F2 DRAM structure places the source, gate, drain, and capacitor from bottom to top, with the word line and bit line connected to the gate and source, respectively. This configuration can reduce the chip area by approximately 30% compared to the existing 6F2 DRAM. Seo Jae-Wook anticipates that VG DRAM could enter mass production after the 0a nm node.

Samsung Electronics, SK Hynix, and Micron are set to introduce 1c nm DRAM utilizing EUV lithography between 2024 and 2025. For the next-generation 1d nm node, advanced memory production will employ EUV multiple exposure techniques, significantly increasing the lithography costs in the manufacturing process.

Seo Jae-Wook mentioned that adopting a VG or 3D DRAM structure could potentially reduce the EUV lithography costs for memory production to less than half of that associated with traditional 6F2 DRAM.

For VG DRAM, low lithography costs could be maintained for one or two generations of the process, after which EUV costs are expected to rise sharply again. In contrast, the 3D DRAM route would require substantial investment in deposition and etching equipment.

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Neha Jha

A passionate Post Graduate Teacher with knowledge on wide variety of topics.