Source: architect Technology Alliance

this article is from & ldquo; in-depth report& rdquo;. Memory chips belong to the category of integrated circuits in semiconductors and are currently the most widely used and standardized ones. One of the basic products of integrated circuits. Semiconductor can be divided into four categories according to product classification: photoelectric devices, sensor devices, discrete devices and integrated circuits. Integrated circuits account for the highest proportion of semiconductor value, accounting for the market scale of the entire semiconductor industry. Of82.64%, which mainly includes analog chip, microprocessor chip, logic chip and storage chip.

Storage devices are hardware components used to store and read data in computer systems, which can be divided according to different storage media. For optical storage, magnetic storage and semiconductor storage.

Optical memory refers to reading and storing from optical storage media by optical methods A device for storing data, generally refers to optical disc machine, optical tape machine and optical card machine.

Magnetic storage refers to the use of magnetic energy storage the storage and reading process of the magnetic medium equipment for storing information requires the mechanical movement of the magnetic disc, which is widely used at present. PC hard disk, mobile hard disk and other fields;

memory chip, also known as semiconductor memory, refers to the use of electric energy to store information semiconductor dielectric equipment, its storage and reading process is reflected in the storage or release of electrons, widely used in memory, U disk, consumer electronics, smart terminals, solid state storage hard disks and other fields.

According to whether the stored information is retained after power failure, the storage chip it can be divided into volatile memory chips ( RAM) and non-volatile memory chips ( ROM).

RAM is a random memory, data will not be saved after power failure. The main products include SRAM and DRAM, DRAM that is, Dynamic random memory, using capacitor storage, DRAM A bit of uses a capacitor and a transistor to store. Because the capacitor will leak electricity, it is necessary to refresh the storage unit regularly to maintain data; SRAM that is, static random memory, its internal structure ratio DRAM complex, data can be saved without refreshing the circuit.

ROM is a kind of memory for storing fixed information, in normal working state only data can be read, and data cannot be modified or re-written immediately. Data can still be saved after the external power supply is cut off. Slow but larger storage capacity, mainly including EEPROM(Charged erasable programmable read-only memory), Flash ( flash memory chip), PROM ( programmable Read-Only Memory), EPROM ( erasable programmable read-only memory) and so on.

According to the specific function, the memory in the computer can be subdivided into registers, cache, main memory, disk cache, fixed disks, and removable storage media6 layer. From CPU Cache, memory SSD and HDD, structure it has become a computer storage system. Each layer only exchanges data with adjacent layers. As the level changes from high to low, the equipment capacity becomes larger, li CPU the distance becomes farther, the access speed becomes slower, the transmission time becomes longer, and the cost per byte becomes cheaper and cheaper.

CPU the Register in is at the top and is marked L0, it uses SRAM chip made, integrated in CPU the limited capacity, extremely fast, and CPU synchronization;

cache is a small and fast memory, generally used DRAM buffer, using SRAM technical implementations are usually integrated in CPU internal;

primary storage DRAM composition, and SRAM different, it has higher storage density, larger capacity, lower price and slower speed. Overall, SRAM high price, fast speed, DRAM cheap, larger capacity, SSD and HDD as an external storage device, the hard disk has larger capacity, lower cost, and CPU farther and slower access speed.

DRAM and FLASH it is the most important storage chip in the market at present. FLASH can be divided NOR and NAND the difference between the two is that the storage unit connection methods are different, resulting in different reading methods, NAND read speed ratio due to Pin Multiplexing NOR slower, but the erasure and write speed ratio NOR much faster; NAND the internal circuit is simpler, so the data density is large, the volume is small, and the cost is also low. Some large-capacity ones on the market FLASH all adopted NAND type, for example SSD, U disk, SD card, EMMC.

Compared Flash and Nor, DRAM it has the advantages of high read/write speed and short storage time, but the unit cost is higher. High, mainly used PC memory( for example DDR) mobile phone memory( for example LPDDR) and servers.

Storage chip industry chain participants include suppliers of semiconductor materials such as silicon wafer, photoresist, target material, polishing material, electronic special gas and lithography machine, PVD, CVD, etching equipment, cleaning equipment, sealing testing equipment and other semiconductor equipment suppliers.

The middle reaches of the industry chain are stored storage chip manufacturers are mainly responsible for the design, manufacture and sealing testing of storage chips. Common storage chips include DRAM, NAND flash memory chip and NOR flash memory chips, etc;

the downstream of the industrial chain are consumer electronics, automotive electronics, information and communication, and people for enterprises in application fields such as AI, all kinds of electronic and intelligent devices cannot be separated from storage chip applications.

The storage chip industry chain mainly consists of sets it is composed of circuit design, wafer manufacturing, packaging and testing, module manufacturer integration and other links. From the perspective of business model, it mainly divided IDM and vertical division of labor.

IDM mode refers to enterprise business coverage IC design, manufacture, package and test all link, most major international storage chip factories are IDM mode, such as Toshiba Semiconductor, Samsung Semiconductor, flying cable semi-conductor large multinational enterprises such as sports and Meguiar's technology.

Vertical division of labor mode, namely Fabless(Made without wafer design company) Foundry(Wafer foundry) OSAT(Encapsulation test Enterprise), Fabless mode means no wafer production line Integrated Circuit Design mode, that is, enterprises only design and sell integrated circuits, manufacturing, packaging and testing, etc. Outsourcing of production links, such as Qualcomm, MediaTek, AMD, Huada Semiconductor, etc; Foundry namely wafer foundry, it is an industrial operation mode that is only responsible for chip manufacturing but not chip design.

Established in TSMC in the past, the semiconductor industry only IDM A model, after more than half a century of development, the global semiconductor industry chain is gradually moving division of Labor and integration trend development.

DDR, LPDDR, GDDR based on DRAM three memory specifications or standards. Solid State Technology Association( JEDEC) defines three types DRAM standard categories to help designers meet the power consumption, performance, and specification requirements of target applications.

Standard DDR: for servers, cloud computing, networks, laptops, desktops, and consumer applications with wider channel width, higher density and different shapes and sizes, its development route is improved by increasing the core frequency. Performance.

Mobile DDR( LPDDR): for mobile electronic products and automobiles, which are very sensitive to specifications and power consumption, it provides narrower channel width and a variety of low-power operating states. The previous four generations were based on the same generation. DDR development, after the fourth generation, is based on the application side to develop independently, through improvement Prefetch pre-read digits to improve performance.

Graph DDR (GDDR): for data-intensive applications that require extremely high throughput, such as graphics-related applications, data center acceleration, and AI, is applied to high-end graphics cards with high performance DDR memory, focusing on data bit width, far exceeding the same period DDR the operating frequency.

LPDDR, that is, low power Double Rate Synchronous dynamic random memory, yes DDR SDRAM, also known mDDR( Mobile DDR SDRAM), has more than the same generation DDR lower memory power consumption and smaller volume.

GDDR, is used for display RAM technology, which is characterized by high bandwidth and high latency the latest Standard is GDDR6,2022 year7 in January, Samsung launched the first model24Gbps processing speed GDDR6 video memory.

Divided by storage unit density, NAND Flash can be divided SLC, MLC, TLC, QLC four types.

SLC is a single-level unit, storage per unit1 bitdata provides high performance and durability.10 ten thousand P/E cycle, but low capacity and high cost, is often used in industries that require high read/write durability, such as servers, military industry, etc.

MLC belongs to multi-level units, storage per unit2 bit Data, Data density ratio SLC high, can be bigger the storage capacity1 ten thousand P/E cycle, durability ratio SLC low, MLC it is widely used in servers and work regulations.

TLC is a level 3 unit, storage per unit3 bit Data, performance and durability decline, P/E cycle down to maximum3000 however, the capacity can be larger and the cost can be lower. It is widely used in consumer products and has the highest cost performance. The storage solution achieves a good balance in performance, price, capacity and other aspects.

QLC unit 4, storage per unit4 the performance and durability of bit data are further deteriorated, P/E period only1000 but the price is cheap, the storage capacity in the unit space is higher, and the consumption-level large capacity SSD use QLC NAND flash particles.

NAND experienced2D NAND period, now enter3D NAND period.2D NAND storage count the data units are placed horizontally side by side, and the space for placing units is limited. Reducing the units will reduce the reliability;3D NAND increase stacking units vertically and increase the number of transistors per unit area to obtain higher storage density and achieve higher storage capacity. In addition, it has higher durability and lower power consumption, at the same time, it will not lead to a sharp rise in prices.

On the market3D NAND it is mainly divided into traditional parallel architecture and CuA( CMOS under Array) architecture,2018 in, Changjiang Storage announced its breakthrough3D NAND architecture Xtacking, the key technology of wafer bonding3D NAND flash memory is realized, with the increasing number of layers, based on Xtacking developed and manufactured3D NAND flash memory will have more cost and innovation advantages.