PART 1: SEMICONDUCTOR MANUFACTURING Introduction to semiconductor manufacturing
Semiconductor Manufacturing is a critical industrial process that leads to mankind’s easy tech-based lifestyle through consumer electronics, appliances, electrical vehicles, IoT, and many more applications. This five-part article series details the process of semiconductor manufacturing straightway from the books to the one inside the phone in your pocket. This article discusses the basics of semiconductor manufacturing and some statistics.
Industry overview of semiconductor manufacturing
The semiconductor manufacturing industry stands at a valuation of USD580.1 billion as of 2022 and is expected to reach USD1,883.7 billion in the upcoming 10 years! The capability of a country to produce semiconductors is a way to estimate its manufacturing sector. So far, only 10 countries are manufacturing semiconductors that empower the entire world. Major semiconductor companies are expanding their operations even more in the top production countries. Malaysia, Israel, and The Netherlands have the lowest numbers but a huge potential for semiconductor manufacturing. Moreover, companies like FOXCONN and Intel plan to expand their operations in newer countries like India, Vietnam, etc.
Semiconductor manufacturing process
The process of producing semiconductor devices from wafers is called semiconductor manufacturing. Semiconductor manufacturing is often termed as semiconductor fabrication. “Semiconductor microfabrication” is another process that enables the production of extremely small semiconductors at microscopic and nanoscale levels. The ultimate goal of semiconductor manufacturing is to produce highly reliable, low-cost cost, and high-quality semiconducting devices or chips.
Experts divide semiconductor manufacturing processes into 6, 7, 8, 10, or 12 steps. However, similar processes add up to a broader category. A manufacturing unit, referred to as a “foundry”, is the place where semiconductors are produced. It must be noted that not all foundries do follow the listed steps rigidly in the sequence. Each company may have its own procedures and regulators.
Watch this video to get the chip manufacturing process explained:
Step 1: Wafer Manufacturing
The first step in semiconductor manufacturing is to produce wafers. A semiconductor wafer is made from semiconducting materials such as silicon, silicon carbide, gallium arsenide, etc. The impure material is melted to form a high-purity liquid that is crystallized through processes such as Czochralsk and various others. The cylindrical-shaped ingot is sent for slicing, polishing, and further procedures.
Step 2: Oxidation
The process of oxidation develops an oxide layer that provides insulation inside semiconductor devices. The insulating layer of oxide protects the wafer and prevents unwanted connections inside the device. Such insulation is required to define the junction area and isolate the gate terminal in FETs. Two methods include dry and wet oxidation to form an oxidized thin layer.
Step 3: Photolithography
A photoresist is a UV light-sensitive material that is coated over the wafer. Depending upon the manufacturing process, positive and negative photoresist can be used. A desired patterned mask, a circuit designed through an EDA tool, is placed over the wafer as it is exposed to UV light. In simple words, photolithography is the process of placing thin-film circuits on the semiconductor to define precise patterns (or circuits).
Step 4: Etching
After the photolithographic stage, the etching process removes the unwanted material from the wafer. The etching process ensures the correct geometry of the circuit pattern for the semiconductor. The wafer undergoes the etching process many times while the desired part is protected through a mask. Two types of etching processes are used in the industry- dry etching and wet etching.
Step 5: Doping
The doping process involves adding pentavalent or trivalent impurities to enhance the conductivity of the semiconductor device. A common doping method used in the semiconductor manufacturing process is ion implantation. Impurities are accelerated and ions are introduced in the wafer during the process. Post ion-implantation process, the wafer goes through the process of annealing to check the quality of dopants and repair any possible structural damage at the crystal level.
Step 6: Metallization
The process of metallization in semiconductor manufacturing allows electricity to flow inside the device. Various components like transistors, resistors, capacitors, etc., are connected for the semiconductor to function as predicted. In simple words, metallization is the metal wiring to make interconnects and ohmic contacts in the semiconductor. Thin films are engineered inside the small semiconductor to provide a path for the current to flow.
Step 7: Quality control and packaging
The electrical die sorting (EDS) process performs quality checks and tests the manufactured semiconductor for reliability. The process is a final check to eliminate faults inside the wafer. Packaging semiconductors is the last step of the manufacturing process. Semiconductors are cut from the wafers separately and are put in different shapes and packages. The foundry sends the packaged device to the selling unit, finally reaching the consumers.