Semiconductors Basics: Types, Manufacturing, Applications & More

In the early days of my engineering degree, I always thought about how these microchips and electronic components are made and how they work. So after learning these things I realized that this technology is quite complex but it is very interesting. 

Do you want to learn about semiconductors and their manufacturing processes? Then you are at the right place. In this blog post, I am going to explain this emerging technology of semiconductors in a simple way. I hope you will enjoy learning. 

Table of Contents

Introduction :

In the current digital era, semiconductors have become a crucial component of our daily lives. Semiconductors are a common component in almost all electronic devices, including laptops, smartphones, automobiles, and industrial machinery. We will examine the fundamentals of semiconductors, their types, and the design and manufacturing procedures involved in their creation in this article.

How do semiconductors work?

Materials known as semiconductors fall between the categories of insulators and conductors (such as copper and aluminum). (e.g. rubber, glass). Under specific circumstances, such as when exposed to light, heat, or voltage, these materials have the capacity to conduct electricity. In addition to silicon, other materials like germanium and gallium arsenide are also used as semiconductors, but silicon is the most popular. 

 Silicon (image credit: wikipedia.org)

Semiconductors' behavior is largely determined by their electronic structure. A semiconductor crystal's atoms are arranged in a regular pattern to form a lattice structure. Valence electrons, or the outermost electrons of each atom, are shared by neighboring atoms to form covalent bonds. The electrons in these covalent bonds are localized around the atoms, making free movement through the material difficult.

At low temperatures, however, some electrons in covalent bonds can gain enough energy to break free from their atoms and become mobile. These mobile electrons are known as charge carriers, and they are responsible for the semiconductor's electrical conductivity.

Types of Semiconductors:

Semiconductors are divided into two types:

1) Intrinsic Semiconductors 

Intrinsic semiconductors are pure semiconductors that are not doped with impurities on purpose. They contain only one type of semiconductor material, such as pure silicon or germanium. At room temperature, intrinsic semiconductors have a low concentration of mobile charge carriers, making them poor conductors. At higher temperatures, however, they become more conductive as more electrons gain enough energy to become mobile.

2) Extrinsic Semiconductors 

Extrinsic semiconductors are those semiconductors that have been purposefully doped with impurities to alter their electrical properties. Doping is the process of adding small amounts of impurity atoms to a semiconductor material during the manufacturing process, such as boron or phosphorus.

Extrinsic semiconductors are classified into two types:

• N-Type Semiconductors :

Impurities with extra electrons in their outermost shell are used to dope N-type semiconductors. Donor impurities are impurities that donate extra electrons to the semiconductor crystal. The extra electrons become mobile charge carriers, increasing the material's conductivity. The majority of charge carriers in n-type semiconductors are electrons.

• P-Type Semiconductors :

To dope P-Type Semiconductors, the impurities which have fewer electrons in their outermost cell are used and these impurities are known as acceptor impurities because of holes in the semiconductor crystal. The holes function as positive charge carriers and can move through the crystal in the same way that electrons can in an n-type semiconductor.  In p-type semiconductors, the majority of charge carriers are holes.

Semiconductor Design and Manufacturing Processes:

Semiconductor design and manufacturing is a complex and highly specialized field. There are several steps involved, including crystal growth, wafer fabrication, and device fabrication.

Crystal Growth

Growing a pure crystal of the semiconductor material is the first step in semiconductor manufacturing. The Czochralski method is used to grow the crystal in a high-temperature furnace. This involves melting a large amount of semiconductor material in a crucible and gradually drawing a seed crystal out of the molten material. The crystal solidifies as it is pulled out, forming a single crystal with a uniform lattice structure.

Wafers Fabrication 

After growing the crystal, it is cut into thin, circular wafers with a diamond saw. These wafers have a diameter of 200-300mm and are only a few millimeters thick. Then the wafers are polished to remove any surface imperfections and create a smooth, flat surface. This surface will serve as the foundation for the fabrication of semiconductor devices. After this, a series of processes are used to create different layers on the wafer's surface. These layers are used to create semiconductor device components such as transistors and diodes.

The following processes were used to create these layers:

• Deposition: The deposition is the process of depositing a thin layer of material onto the surface of a wafer using techniques such as chemical vapor deposition (CVD) or physical vapor deposition (PVD)
• Etching: A chemical or physical process used to remove material from the surface of a wafer. This is done to create patterns and structures in the different layers.
• Lithography: Lithography is the process of selectively exposing parts of the wafer surface to light or other radiation using a mask. This is used to build patterns and structures in the different layers.

Semiconductor Manufacturing Process

Device Fabrication

After the layers are deposited and patterned, the wafer is cut into individual semiconductor devices. Each device may contain several components such as transistors and diodes, as well as interconnects and packaging. Individual devices are then tested to ensure they meet the specifications. This testing may include measuring the electrical properties. After being tested and verified, the devices can be packaged and integrated into larger systems such as microprocessors or memory chips.

Applications of Semiconductor in electronics:

Semiconductors are found in a variety of electronic devices and systems, ranging from simple diodes and transistors to complex microprocessors and memory chips. Here are some of the most common semiconductor applications in electronics:

1) Diodes:

Diodes are fundamental semiconductor devices that allow current to flow in only one direction. They are commonly used in power supplies and to convert alternating current to direct current power. They're also used in lighting, like LEDs.

2) Transistors:

Transistors are semiconductor devices that can be used to amplify or switch electronic signals. They are used in a variety of electronic circuits such as amplifiers, oscillators, and digital logic circuits. Microprocessors and Microcontrollers which are used in computers and other digital devices rely on transistors.

Semiconductor Devises List

3) Memory Storage Units:

Memory devices are semiconductor devices that store digital information. Memory is classified into three types: dynamic random-access memory (DRAM), static random-access memory (SRAM), and flash memory. Computers, smartphones, and digital cameras all use memory devices.

4) Optoelectronics:

Optoelectronics is a branch of electronics that studies how light interacts with electronic devices. Semiconductors are found in a wide range of optoelectronic devices, such as light-emitting diodes (LEDs), photodiodes, and laser diodes. These devices are used in a variety of applications including lighting, displays, and communications.

5) Power Electronics:

Power electronics is a subfield of electronics concerned with the regulation and conversion of electrical power in a circuit. Semiconductors are used in devices such as rectifiers, inverters, and voltage regulators in power electronics.

How Microprocessors and Microcontrollers are Manufactured using Semiconductors :

A microprocessor and Microcontroller is a complex integrated circuit (IC) that includes millions of transistors and other components packed. The following steps are typically involved in the design of a microprocessor:

1. Material selection: Because of electrical properties and availability, silicon is commonly and mostly used as the base material for microprocessors.
2. Circuit Design: Circuit design for a microprocessor includes selecting and arranging the appropriate components, such as transistors and memory cells and their connections to meet the desired performance specifications.
3. Simulation: The circuit design is simulated using software tools to test and optimize its performance under various conditions.
4. Verification: The circuit design is then prototyped. The prototype chip is tested for performance, power consumption, and other factors, and then necessary changes are made. Power consumption is a very important factor in chip design because this will affect the performance of batteries in devices like smartphones, tablets, and laptops.
5. Fabrication: Once the design has been verified, the microprocessor is fabricated using semiconductor manufacturing processes. This involves depositing and patterning multiple layers of material on a silicon wafer to create the various components of the microprocessor as mentioned earlier in the post.
6. Testing: After fabrication, the microprocessor chip is then tested to check its performance and then it is packed and it is now ready to integrate into larger systems and circuits, such as computers or smartphones. 

Conclusion :

In conclusion, a semiconductor (Silicon) is a very important element in the manufacturing of microprocessors and microcontrollers. It is also a base material for the various components of electronic circuits like transistors, diodes, capacitors, and other ICs. Without semiconductors, it would be impossible to create integrated circuits (ICs) that are essential to modern technology. 

From normal Silica to high-performance microprocessors it is a very complex process of designing and manufacturing and takes lots of time to get a simple chip.  Due to this complexity, there is less production of chips and demand is very high in the market.  But I tried to explain this process in a very simple way in this post. Hope now it is cleared in your mind about semiconductor and how semiconductor is used in electronics.