How is memory made? What is memory used for?

DRAM, SRAM, FLASH, MRAM, RRAM signals are all stored by the charged charge on the "gate stage" of the "MOSFET" (0 or 1, of course, in some designs, the charge may have many voltage levels, such as a cell stores 2 bits information, etc., the principle is the same). When reading, the source gives a voltage, and the current or voltage on the other side can be tested to know whether the gate stage is charged. (There are variations of different memory in the above quotation marks, but the principle is similar, RRAM and MRAM are measurement resistors).

In terms of production, I don't think it's very different from logic (this must be a mistake that professionals think is outrageous). It's like steaming buns. On a silicon wafer, things keep growing, corroding, and shining on things.

And then some people are studying this every day, and the time is longer, whether the steamed buns will be more delicious...

First of all, we have to understand the "integrated circuit" industry, almost all electrical appliances are inseparable from chips, whether it is the CPU in the computer, memory, or all kinds of chips in the TV mobile phone or even the first SLR, can be divided into integrated circuits. The process of making them is much the same.

It is recommended to find a book related to integrated circuits, and the entire industrial process will be introduced. For example, the second chapter of the book "Digital Integrated Circuits - Design Perspectives" that I have in hand has a very detailed explanation throughout the chapter. By no means "a diode on a chip is a CPU", the industrial process alone is complex, not to mention the specific functional design.

CPU and memory are the same thing, and the industrial process is similar, but the functional design is different.

As for the physical principle, it is more complicated, you can first go to the direction of digital circuits to understand, but that is only the principle of logic, the real physical principle you have to go deep into the field of semiconductors, first learn some knowledge of analog circuits, at least you must first understand the basic concepts of MOSFET (a type of semiconductor device). Once you understand how semiconductors work, you will understand the physics by looking at the corresponding chapter in the book (or Chapter 12 of that book).

In fact, memory is only one type of memory (DRAM), and there are also SRAM, ROM, FLASH ROM, SSD, etcSome do not use MOSFET devices, and many chips have their own different processes, and MOSFETs are just one of the most commonly used. In fact, you will gain something from an in-depth understanding of the physics of diodes (what is a pn junction, carrier motion).

** of the gala scoop. Taste Cylinder Cylinder Drop!

There is a very important part of the structure of a computer, which is memory. Memory is a part used to store programs and data, for a computer, with memory, there is a memory function, in order to ensure normal operation. There are many types of memory, which can be divided into primary memory and auxiliary memory according to their purpose, and the main memory is also known as internal memory (referred to as memory).

Memory plays a pivotal role in a computer. Memory generally uses semiconductor memory cells, including random access memory (RAM), read-only memory (ROM), and cache. Simply because RAM is the most important memory of them all.

s（sysnecronous）dram

Synchronous Dynamic Random Access Memory: The SDRAM is 168 pins, which is the memory currently used by Pentium models and above. SDRAM locks the CPU and RAM together through the same clock, enabling the CPU and RAM to share a clock cycle, work synchronously at the same speed, and the rising edge of each clock pulse starts to pass data at a speed that is 50% faster than EDO memory.

ddr（double

datarage）ram

An update to SDRAM, it allows data to be transmitted on the rising and falling edges of the clock pulse, so that the speed of the SDRAM can be doubled without increasing the frequency of the clock.

MemoryMemory is the place where programs and data are stored, for example, when we are using WPS to process documents, when you type characters on the keyboard, it is stored in memory, and when you choose to save, the data in memory will be stored in the hard (magnetic) disk. Before we can understand it further, we should also recognize its physical concepts.

1.How memory works.

Obviously, the subject is referring to the common memory modules in PCs, which belong to the Dynamic Random Access Memory (DRAM), which is a very simple and easy-to-understand memory unit, consisting of an N-type field-effect transistor (NMOS FET) and a capacitor (as shown in the figure below).

This structure is actually very much like a building, and the process of chip manufacturing is also a bit like the process of building a building, and the very simplified steps are as follows:

Design drawing, that is, the layout of the chip; The layout is a layered, top-down view that contains information about the physical shape of each layer and the location connections between layers. The layout is converted into masks, each of which is a top-down view of a certain layer, and there are often dozens of masks on a chip. Each layer of the chip is made at the same time, just like building a floor requires 3 floors to be built before building a 4th floor.

Leveling the land. There's nothing to say about this, most of the chips start from a flat wafer, and the wafer needs to be cleaned.

foundations and substrata. This is the most critical and complex step in the manufacturing process, as all important active devices such as transistors are at the bottom of the circuit. First of all, it is necessary to draw lines (photolithography) to define, to dig out, to retain, then dig pits (ecthing etching), do solidification where it is needed (ion implantation), build walls and lay pipes (chemical deposition and physical deposition, CVD &PVD) and so on.

The specific steps are very complex, often requiring a dozen masks to complete, but you can figure out how a building grows out of the ground.

Senior. The higher layers are relatively simple, or the line is decided (light photolithography) **to make walls or columns, ** space, and then deposition metal to grow these things. These layers are basically copper or aluminum metal connections, and there are few complex components.

Cap. To do a layer of metal compound curing protection, of course, the connection point (pad) should be exposed.

Washing, cutting. There is no way to build a building in this step... A 300 mm diameter wafer can have hundreds or thousands of chips on it, cut like a cake.

Encapsulation. It's a bit like decorating the façade, and then giving the whole building water, electricity, and ventilation. A small piece of silicon becomes what we often see, with the required signals and power connected to solder balls or pins.

Packaging is a big science, which has a huge impact on the electrical performance of the chip.

** of the gala scoop. Taste Cylinder Cylinder Drop!

First of all, the quality of the particle itself has an almost decisive impact on the quality of the memory module. An excellent particle is like a girl to be married, and it must have two conditions: "after a famous family" and "innocent".

Secondly, high-quality accessories are also an indispensable condition for excellent memory modules to be refined. "Famous ladies" can only be "chic out of the cabinet" if they are accompanied by a weighty dowry.

The impact of a high-quality PCB on memory particles is similar to the role of a stable and reliable motherboard relative to the CPU.

The third trick: quality comes from excellent technology, and welding quality is a very important factor in memory manufacturing.

Cheap solder and unreasonable soldering process will produce a large number of virtual soldering, and after a period of use, the gradually oxidized virtual solder joints may produce random failures.