The Foundation of the Semiconductor Industry: What is A Wafer?
Knowledge

The Foundation of the Semiconductor Industry: What is A Wafer?

In the semiconductor news, wafers are always mentioned in terms of dimensions, such as 8-inch or 12-inch wafers, but what exactly is a so-called wafer? What does the 8 inches refer to? How difficult is it to produce large-sized wafers? The following is a step-by-step introduction to the most important foundation of semiconductors - what is a "wafer".
Published: Aug 25, 2022
The Foundation of the Semiconductor Industry: What is A Wafer?

What is A Wafer?

Wafers are the basis for the manufacture of various computer chips. We can compare chip manufacturing to building a house with Lego blocks, and by stacking layer by layer, we can complete our desired shape (that is, all kinds of chips). However, if there is no good foundation, the built house will be crooked and unsatisfactory. In order to make a perfect house, a stable base plate is required. For wafer fabrication, this substrate is the wafer described next.

First of all, recall that when I was a child with Lego blocks, there would be a small round protrusion on the surface of the blocks. With this structure, we can stably stack the two blocks together without using glue. Wafer fabrication, in a similar way, holds the subsequently added atoms together with the substrate. Therefore, we need to find substrates with neat surfaces to meet the conditions required for subsequent fabrication.

In solid materials, there is a special crystal structure - Monocrystalline. It has the property of atoms closely arranged one after the other, which can form a flat atomic surface. Therefore, using a single crystal to make a wafer can meet the above requirements. However, how to produce such a material, there are mainly two steps, namely purification and crystal pulling, after which such a material can be completed.

How To Make a Single Crystal Wafer

The purification is divided into two stages. The first step is metallurgical purification. This process is mainly to add carbon to convert silicon oxide into silicon with a purity of more than 98% by means of redox. Most of the refining of metals, such as iron or copper, is done in this way to obtain metals of sufficient purity. However, 98% is still not enough for wafer manufacturing and still needs to be improved further. Therefore, the Siemens process will be used for further purification, so that the high-purity polysilicon required for the semiconductor process will be obtained.

Next, is the step of pulling crystals. First, the previously obtained high-purity polysilicon is melted to form liquid silicon. After that, the single-crystal silicon seed contacts the liquid surface, and slowly pulls up while rotating. As for why single-crystal silicon seeds are needed, it is because silicon atoms are arranged in the same way as people line up, and they will need to be in the front line to let later people how to arrange them correctly. Finally, after the silicon atoms leaving the liquid surface solidify, the neatly arranged monocrystalline silicon pillars are completed.

However, what do 8 inches and 12 inches stand for? In fact, it refers to the crystal column. How difficult is it to make large wafers? As mentioned earlier, the production process of the crystal column is like making marshmallows, and it is formed while rotating. Anyone who has made marshmallows should know that it is quite difficult to make large and solid marshmallows, and the process of pulling crystals is the same. The speed of rotation and temperature control will affect the quality of the crystal column. Therefore, the larger the size, the higher the speed and temperature requirements for crystal pulling, so it is more difficult to make high-quality 12-inch wafers than 8-inch wafers.

However, an entire silicon pillar cannot be used as a substrate for wafer fabrication. In order to generate silicon wafers one by one, a diamond knife is used to cut the silicon pillars laterally into wafers, and the wafers can be polished to form wafers. Fabricate the required silicon wafers. After so many steps, the fabrication of the wafer substrate is complete, and the next step is the step of stacking the house, which is wafer fabrication.

Published by Aug 25, 2022 Source :Business Next

Further reading

You might also be interested in ...

Headline
Knowledge
What Exactly is a Planning Machine?
In recent years, various industrially advanced countries have used machines to replace manpower for bench work, making the application of machine tools more extensive and important. Although the processing precision of milling machines and grinding machines is superior to that of planers, the price is more expensive than planers. Generally, small and medium-sized factories still use planers for many initial processing tasks in order to take into account equipment investment costs. So what exactly is a planer? Let's take a look together.
Headline
Knowledge
Simultaneous Tapping Control Structure and Adjustment Technology
With the rapid development of 3C products and the aerospace components industry, the technology of CNC machine tool rigid tapping is more widely used.
Headline
Knowledge
What is a Turbocharger?
Turbochargers are often used to increase the intake air volume of an internal combustion engine, thereby increasing horsepower output.
Headline
Knowledge
What are Turbine Blades?
Turbine blades are an important component of the turbine section in a gas turbine engine. The high-speed rotating blades are responsible for drawing high-temperature and high-pressure air into the burner to maintain the engine's work.
Headline
Knowledge
What are EMRs and EHRs? Indispensable Medical and Health Data Systems in Smart Healthcare
EMR (Electronic medical record) is focused medical data, mainly used by clinicians for diagnosis and treatment. EHR (Electronic health record) focuses on personal health data, which includes the state of physical, mental, or mental health. EHR has a wider range than EMR.
Headline
Knowledge
High-Speed Transmission Technology - Universal Serial Bus 4
The demand for high-speed transmission is increasing day by day, which has promoted the rapid development of USB (Universal Serial Bus) technology in recent years. The introduction of a central processing unit (CPU) that supports USB4 symbolizes that USB technology has entered a new era.
Headline
Knowledge
What are the Classifications of Abrasives?
Abrasives are a general term for abrasives and abrasive tools, including abrasive products and abrasive products.
Headline
Knowledge
What is Power Machinery?
The manufacture, operation, and maintenance of land, sea, and air vehicles are all covered in the power machinery industry.
Headline
Knowledge
Tech to Wear: Technical Textiles
One of the simplest ways of classification is to classify textiles other than general clothing and home decoration textiles as technical textiles. Let’s see what are so called Technical Textiles.
Headline
Knowledge
What is the Textile Industry?
The upstream of the textile industry chain is the petrochemical raw material. After being manufactured into nylon fiber, polyester fiber, rayon fiber, carbon fiber and other human fiber products, it is spun into yarn, then woven into cloth, and then bleached, dyed, printed, Dyeing and finishing procedures such as coating, finishing, tailoring and sewing into garment products or other related textile products. The textile manufacturing process can be divided into four stages: fiber, textile, dyeing and finishing, ready-to-wear/home textiles, among which textiles can be further divided into two steps: spinning and weaving: spinning is the transformation of roving into spun yarn. After being sent to the factory, the yarn is inserted into the operation axis of the textile machine table, and the textile machine table pulls the yarn upward and sends it to the textile machine; the next step is the weaving step, at this stage, the shuttle is used in the textile machine. It shuttles back and forth continuously, and finally weaves it into a piece of cloth. After finishing the cloth fabric (including cotton, wool, synthetic fiber, etc.) into a box, it can be sent to downstream manufacturers for post-processing to form a textile industry chain.
Headline
Knowledge
The Automatic Detection Method of Total Hydrocarbons in Air
Total petroleum hydrocarbons are a mixture of many different compounds. People can be exposed to total petroleum hydrocarbons in several ways, including fuel pumps, oil spilled on the road, and chemical use at work or home. Certain total petroleum hydrocarbons can affect the nervous system, causing headaches and dizziness.
Headline
Knowledge
Underwater Robotics - Science and Technology for Subsea Exploration
Underwater robotics is not only used in rescue and search, it has already been used in marine resource exploration, seabed topographic mapping, and the construction and maintenance of marine engineering structures.
Agree