When it comes to flash memory, many people think of running memory and storing memory. Friends who care about mobile hardware should be familiar with CPU, GPU, screen and battery components, but RAM (running memory) and ROM (also important for product performance). Storage memory) I believe that there are not so many people who know a lot. Today's article, let's talk about the storage of memory. First of all, unlike the CPU, the evaluation of the performance of the ROM is not related to the computing power. There are only two indicators for measuring the performance of a flash memory and memory: data read and write speed and capacity.
3D NAND is a stimulant for flash memory capacity
3D NAND flash risesRegarding capacity, it is first necessary to emphasize that mobile storage capacity, solid state drives (SSD), USB flash drives and SD cards are all used as a storage medium called NAND. Traditional storage media also have mechanical hard disks (HHD), which is traditional. The disc is stored. The characteristic is that the stored data can be kept without loss after power-off, and can be used for storing data. The so-called RAM (running memory) is to store data through some kind of capacitor (DRAM, SRAM or RRAM). After the power is turned off, the data disappears immediately, but the data throughput speed is fast, so I won't go into it here.
We all know that Apple has doubled its iPhone capacity as a whole, from the previous 16GB/64GB/128GB to 32GB/128GB/256GB, so even this year's iPhone7 sales can't compare with last year's iPhone6s, but The demand for NAND flash memory is still nearly doubling, and the price of solid-state hard drives continues to fall. This is a luxury hard drive that has now entered the homes of ordinary people and the demand has increased greatly. The production of NAND flash memory needs to increase substantially. In addition, many 2D NAND production lines are available for the latest 3D NAND flash memory, and 3D NAND technology is the biggest boost to the rapid growth of flash memory capacity in recent years.
3D NAND technology process proposed and popularized
If traditional 2D-NAND wants to increase the storage capacity on the same chip size, the NAND cell unit process needs to be smaller and smaller, so that more memory cells can be inserted in the unit area, but the physical thing always has limits. After the 20nm process, as the unit volume is further reduced, more and more serious electronic interference will occur, which will reduce the reliability and read/write performance of the memory chip.
In this dilemma, 3D NAND technology has been proposed. Simply put, the original planar NAND cell is added with a vertical stack. This vertical alignment can increase the available volume several times at the microscopic level. However, because the body of a single cell unit is small, it does not increase the volume at the macro level. And because the available volume has doubled, the flash memory using 3D NAND stack can use a more mature process, so the 3D NAND flash memory produced by Samsung, Intel and other manufacturers are using the 30nm process instead of the process below 20nm. Bringing more excellent reliability to 3D NAND. For example, the number of erasing and writing of MLC flash memory under the current 20nm process is generally 3,000 times, and Samsung's V-NAND flash memory using 3D NAND technology can reach 35,000 times.
It is precisely because of the introduction and popularization of 3D NAND technology that we are now seeing more and more monster-level storage devices such as 1TB SD cards that were previously unimaginable, and in the same chip size, the ROM of the mobile phone and the SSD of the computer, etc. It also has an increasing storage capacity. It is a pity that this technology with bright prospects can be mastered in China. Samsung and Intel have been able to manufacture 36, 48 or even 64-layer 3D NAND stacks. It has also been reported in China some time that SMIC will spend in Wuhan. With $16 billion in DRAM and NAND factories, the current situation is that domestic manufacturers can only produce 4-layer stacked 3D NAND, which is far from the industry giants.
Mainstream memory standard specifications: eMMC standard, UFC standard and NVMe standard In addition to capacity, reading and writing speed is also one of the factors that restrict the experience of use. Presumably everyone has tasted the pain of slow loading of games and applications, but with the introduction of new standard specifications by various manufacturers, it has been inconspicuous in recent years. Mobile phone memory has also ushered in a rapid development. The current memory standard specifications can be divided into three categories, one is the traditional eMMC, and then the UFC standard and the NVMe standard proposed by Samsung and Apple respectively.
In fact, these standards are based on NAND memory chips, plus control chips, access standard interfaces, and standard packaging to form a highly integrated storage module. It's a bit like a SoC in a mobile phone, stuffing all the things you need into one module, which is convenient for mobile phone manufacturers to install directly on the motherboard, simplifying the process of product development. However, these three standards are more than standards on interfaces and data transfer protocols. On storage media, NAND flash memory is used.
eMMC has always been the mainstream memory standard in the industry. In general, eMMC=NAND flash memory control chip standard interface package, UFS and NVMe are also the same, the difference is that the flash control chip and interface protocol are not the same. eMMC has evolved from eMMC4.3 all the way to 4.4, 4.5 until now 5.0, the transmission speed is also from 50MB/S all the way to 200MB/S until now eMMC5.0 400MB/S, and then there are eMMC5.1 up to 600MB/ S transmission speed.
However, in the words of Samsung, the potential of the eMMC standard has been drained, and the UFS standard is the future. eMMC can only read or write one state for a while, while UFS2.0 supports simultaneous reading and writing of data, and can achieve 780MB/S in transmission speed. In terms of power consumption, although the power consumption is higher than eMMC at full load operation, it is much lower in standby mode. There are already a lot of mobile phones using UFS2.0, and UFS 2.0 is already supported by phones that use processors such as Qualcomm Snapdragon 821, 820 and Samsung Exynos 8890.
However, Apple has always been silently composing on the hardware. The iPhone6s and iPhone7 using the NVMe protocol have reached more than twice the read/write speed of the Samsung S7, so the smoothness of the iPhone is not only a system problem, but also on the hardware. Can always be the leading Android camp. However, it is said that UFS2.0 performs better than NVMe in terms of random read/write speed, which means UFS is advantageous in daily complex usage environments. And it is said that Samsung is about to launch the UFS2.1 standard, the read and write speed can reach a staggering 1.5GB / S.
Recently, there have been rumors that Huawei's Kirin 960 processor will support UFS2.1, and as Samsung's own standard, there is a possibility that it will appear in Samsung's mobile phone. I don't know who can be the first in storage speed. The mobile phone manufacturer who beat the iPhone.
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