The answer is—all of the above! How can that be? Let’s start with the evolutionary attributes first.
Quite simply, 3D NAND is still NAND. It’s a block/page-based device with a NAND interface and protocol. This means that controllers and systems that work with conventional (aka planar and 2D) NAND today will not require a major redesign to work with 3D NAND. In fact, in some cases only firmware modifications will be required with minimal or no hardware modifications. Ease of design is what makes 3D NAND evolutionary.
Although 3D NAND looks like NAND to the outside world, it is quite revolutionary on the inside. Flash memory (NOR and NAND) has historically used what we call planar technology. This means that individual Flash storage cells (which store one bit of data) are connected together to form the storage array in a horizontal direction. As we continue to scale the technology (scaling means the cells are closer together, which is how we increase the capacity and reduce the cost per bit), the performance and reliability naturally degrade due to the physics of the Flash cell. Hence, planar NAND technology is reaching its scaling limit. Along comes 3D NAND to save the day. As the name implies, we are now connecting NAND cells in a vertical direction, which gives us more room to relax the cell geometry in the horizontal direction. This provides a continued scaling path for NAND.
A good analogy is building construction. Let’s say we are using a single story (or planar) building for our company. As our company grows and adds more people, we start to get tight on space, packing more people (and their desks, PCs, etc.) closer together. At some point, this becomes impractical, no matter how well our employees get along! The solution is to move to a multi-story (3D) building, where we have plenty of space for our employees and room to continue to expand. Of course, multi-story building construction is more complicated than single-story. Now think about Flash, where billions of cells are connected together on a piece of silicon about the size of your fingertip. As you can probably guess, the techniques Micron is using to connect NAND in the vertical direction are quite revolutionary.
Last but not least, 3D NAND will be disruptive to the Flash storage market. Micron will introduce products at a very low cost per bit, with very good performance and reliability, which will enable new applications for NAND Flash that we can’t even envision today. You can have your cake and eat it too!
About Our Blogger
Kevin is Micron Technology's Director of NAND Marketing.