An Industry First by Samsung: Mass Production of 3D Vertical NAND Flash

Last week, Samsung Electronics Co., Ltd. began to mass produce the industry’s first ever three dimensional (3D) Vertical NAND (V-NAND) flash memory chip. This is a breakthrough from the current planar or 2D NAND. It also raises the scaling limits.

The major gains are seen in performance and area ratio. The new 3D V-NAND is designed to be used in a variety of consumer electronics and enterprise applications. These include embedded NAND storage and solid state drives (SSDs).

The new 3D V-NAND will start with a capacity of a 128GB density in a single chip. This could go as high as 1TB and will most likely depend on customer demand. According to Samsung, the chip utilizes the company’s vertical cell structure based on 3D Charge Trap Flash (CTF) technology and vertical interconnect process technology to link the 3D cell array.

By applying both of these technologies, Samsung’s 3D V-NAND is able to provide over twice the scaling of 20nm class planar NAND flash. The current planar NAND is between 10nm to about 19nm. You may think that stacking layers of NAND will produce thicker chips, but Samsung said the increase "is negligible compared to the most up-to-date planar NAND flash memory chip."

It should be less than a few microns in terms of height increase. In an e-mail response to Computerworld, a Samsung spokesman wrote "The vertical layers in V-NAND cells are measured in nanometers and so stacking them would not make much difference on a micrometer scale."

Jeong-Hyuk Choi, senior vice president, flash product and technology, Samsung Electronics, said “The new 3D V-NAND flash technology is the result of our employees’ years of efforts to push beyond conventional ways of thinking and pursue much more innovative approaches in overcoming limitations in the design of memory semiconductor technology. Following the world’s first mass production of 3D Vertical NAND, we will continue to introduce 3D V-NAND products with improved performance and higher density, which will contribute to further growth of the global memory industry.”

Just to prove this point, Samsung has wasted no time in unveiling the world’s first SSDs based on the new 3D V-NAND memory technology. The new SSDs will come in both a 480GB and 960GB versions. The first round is designed to be used in enterprise servers and data centers.

According to Samsung “The 960GB version offers more than 20 percent increase in sequential and random write speeds by utilizing 64 dies of MLC 3D V-NAND flash, each offering 128GB of storage, with a six-gigabit-per-second serial advance technology attachment (SATA) interface controller.”

Samsung has promised that it will bring this technology to the desktop computer as well in the future. The V-NAND flash chip used inside these SSDs will offer up to 2x the write performance compared to existing 20nm based SSDs. When you add the increased reliability then you have two traits which make it a great match for use in enterprise-class servers.

By making this CTF layer 3D, the reliability and speed of the NAND memory have improved sharply. The new 3D V-NAND shows not only an increase of a minimum of 2X to a maximum 10X higher reliability, but also twice the write performance over conventional 10nm-class floating gate NAND flash memory.

Right now, Samsung’s proprietary vertical interconnect process technology can stack as many as 24 cell layers vertically. It uses a special etching technology that connects the layers electronically by punching holes from the highest layer to the bottom. It is estimated that the limit may be as high as 32.

Gregory Wong, founder and principal analyst at research firm Forward Insights, said, "The real estate stays the same, but you can keep adding levels. And, by adding levels, you can reduce the cost per bit because there are more memory cells, but the real estate to store them does not increase."

After nearly 10 years of research on 3D V-NAND, Samsung now has more than 300 patent pending 3D memory technologies worldwide. With the industry’s first completely functional 3D V-NAND memory, Samsung has strengthened its competitiveness in the memory industry.