CXMT’s progress is moving full steam ahead. A cell architecture called “4F square” for DRAM memory is also being developed by Samsung and SK Hynix, but CXMT is already reporting significant progress. The company aims to release a DDR5 RDIMM for server memory based on this technology before the end of this year.
CXMT, short for ChangXin Memory Technologies, is the major challenger among the three memory manufacturers. Two of them are South Korean; the other is the U.S.-based Micron. The so-called 4F square is a potential means of achieving a further breakthrough. According to the South China Morning Post, this structure makes it possible to achieve much higher density than before.
The company has not yet provided specifications or an exact launch date. In the 4F square structure, each memory cell occupies an area of four times F squared, where F represents the minimum line width of a chip. Commercial DRAM currently still uses the larger 6F structure. Thanks to this new innovation, a cell becomes approximately 33 percent smaller, allowing more cells to fit on a single chip.
Vertical instead of horizontal
At the heart of the approach is a proprietary Vertical Surrounding Gate (VSG) transistor. It features a vertical channel instead of the usual horizontal one. According to CXMT, this reduces leakage current while simultaneously shrinking the cell area. However, existing manufacturing processes proved unsuitable, so the manufacturer had to redesign crucial steps.
According to CXMT, the server segment places higher demands on durability and compatibility. Modules must run continuously, withstand voltage fluctuations, and pass hundreds of compatibility tests with CPUs and motherboards. This makes it a critical stress test for the technology.
It is noteworthy that Samsung does not plan to use 4F square in processes smaller than 10 nanometers until 2028. In addition, it has access to significantly more advanced chip manufacturing equipment from ASML than its Chinese competitors.
New global competitor
CXMT, founded in 2016, has been listed on the Star Market in Shanghai since July. It does not yet have a significant international market presence, but that could change quickly. PC manufacturers such as HP and Acer are considering CXMT as a new source for DRAM production in laptops and PCs. This move is further motivated by the fact that memory is currently extremely expensive and already accounts for roughly 35 percent of the Bill of Materials (BOM), whereas just over a year ago it was around 15 percent.