Understanding semiconductor manufacturing can be gained from this paper

With the continuous progress of science and technology, there is a growing dependence on versatile digital devices. From Bluetooth headsets to smartphones, smart TVs, and even smart refrigerators, these products have become integral to our everyday routines. Yet it is crucial to recognize that the small chip plays a vital role in enabling these experiences. The ongoing growth and advancement of semiconductor industry processes are also responsible for our current level of convenience. So let's take a journey through the history of semiconductor chips together.

What are semiconductors?

Definition of semiconductor

Electrical conductivity divides materials into three categories: conductors, insulators, and semiconductors.

Gold, silver, or copper materials with a conductivity greater than 103s/cm

Semiconductors, such as silicon, germanium, and boron, are between electrical conductivity and resistance

Insulators are materials with conductivities less than 10-8 s/cm, such as glass and plastic

It can also be analyzed using the band structure theory derived from quantum computational mechanics. According to the figure below, the insulator's band gap is about 9 eV, while the semiconductor's band gap is about 1 eV, and the conduction band and valence band of the conductor essentially do not overlap.

Classification of semiconductors

There are also different types of semiconductors based on their composition:

Nowadays, semiconductors are mainly silicon, which we use in our everyday lives. Semiconductors are classified as elements, such as germanium and silicon.

Compound semiconductors, such as gallium arsenide, are made up of two or more elements.

Glass is an amorphous semiconductor that can be either oxidized or not.

Semiconductors are used in the semiconductor industry to prepare chips, and the chips we can use are very large integrated systems.

Part 2 of the Technical Requirements

Ultra-clean technology

At present, dust particles can be controlled at a nanometer level to achieve pollution-free production. This can only be achieved by strictly controlling the dust in the working environment. When using the 0.25 process, one cubic meter of dust with a diameter greater than 0.1 micron cannot contain more than 100 particles.

The highest level of purity

In the manufacturing process, materials, gases, and reagents must be ultra-pure. Impurities can be controlled to a maximum of PPB(billion).

Ultra-fine processing technology

A micromachining process involves the growth and generation of crystals and thin layers, microscopic image processing, and precision control doping of materials with micron or submicron linewidths. Because of these technical levels, the size of each component and the diameter of the substrate determine the integration of an integrated circuit.

In Part 3 of the FEOL, the previous process was described

In semiconductor manufacturing, the front process and the back process are two basic processes. In semiconductor manufacturing, the front process research is of the utmost importance, and there are numerous technical difficulties, the operating system is complex, and it is the core of the entire process. As we proceed, we will discuss the important technologies and processes in the previous path sequentially.

Wafer processing

To make a chip, we first need to make a qualified wafer. The semiconductor industry began with a grain of sand. We make high-quality wafers by extracting high-purity silicon wafers from silica sand that contains more than 95% silica. To create a wafer, three steps are required:

Ingot casting

By using the czochralase method, molten monocrystalline silicon was solidified into rod-like ingots after being heated to remove impurities from silica sand.

Ingot cutting (2)

Using diamond saws to cut the ends of the ingot, the ingot is then cut into slices of a certain thickness. The diameter of the ingot determines the size of the wafer.

Wafer surface polishing (3)

To use such wafers directly, their surfaces must first be ground and chemically etched to remove defects, then polished and cleaned to smooth and complete them.