In the memory sector, the era beyond 10nm seems to be around the corner, as giants have revealed plans on the production of 1c DRAM. SK hynix, according to a report by The Elec, is said to develop a 4F2 (square) DRAM in order to reduce the high cost associated with the extreme ultraviolet (EUV) processes since the commercialization of 1c DRAM.

During an industry conference on Monday, Seo Jae Wook, a SK hynix researcher, questioned the profitability of producing DRAM with EUV technology. Instead, he said that SK hynix is exploring the possibility of manufacturing future DRAMs using vertical gate (VG) or 3D DRAM structure, according to the report.

Sources cited by the report indicate that Samsung and SK hynix are both targeting to apply 4F2 for DRAM at the 10nm node and beyond. According to Seo, by applying VG or the 3D DRAM structure, the cost of the EUV processes can be reduced by half.

SK hynix’s VG, or the so-called 4F2 by memory makers internally, is similar to the vertical channel transistor (VCT) of its South Korean competitor Samsung, The Elec explains.

In short, unlike the traditional 2D DRAM, which only uses the horizontal plane, 4F2, or 3D DRAM, is a cell array structure where transistors are stacked vertically. In the structure, various parts including the source, gate, drain, and capacitor are stacked from bottom to top. As the word line connects to the gate, the bit line connects to the source.

According to the report, arranging the cell array in this manner can reduce the die surface area by 30% compared to 6F2 DRAM.

However, according to a previous report by TweakTown, though the 4F2 design possesses the advantages of being compact and power-efficient, its complexity demands extreme precision in fabrication, higher-quality materials for production, and extensive research to make it scalable and suitable for mass production.

According to TweakTown, Samsung is anticipated to finalize the initial development of VCT DRAM by 2025, with 3D DRAM expected to enter the market by 2030.

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(Photo credit: SK hynix)