Semiconductor manufacturing is a complex and precise process that involves numerous steps to create the tiny but powerful chips that power our modern electronic devices. These chips are the core of nearly every modern electronic device, from smartphones to computers, automotive systems, and advanced medical equipment. Despite the increasing sophistication of semiconductor devices, the manufacturing process can be broken down into six crucial steps, each requiring high precision and stringent quality control.
1. Deposition: Thin films of materials are applied to a silicon wafer.
To create the microdevices inside a chip, we need to continuously deposit layers of thin films and remove the excess by etching, and also add thin layers of materials onto the wafer to separate different devices. These materials can be conductive, insulating, or semiconducting, depending on the desired properties of the final chip. Each transistor or memory cell is built step by step through the above process. The "thin film" we are talking about here refers to a "film" with a thickness of less than 1 micron (μm, one-millionth of a meter) that cannot be manufactured by ordinary mechanical processing methods.
The process of placing a thin film containing the desired molecular or atomic units on a wafer is "deposition". Common deposition techniques include Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD).
2. Photoresist Coating: A light-sensitive layer is added to define patterns.
Before the lithography process, a light-sensitive material called photoresist is applied to the wafer.
This resist is crucial for the next step, as it will be used to transfer the circuit pattern onto the wafer. There are two types of photoresist: positive and negative, each reacting differently to light exposure.
3. Lithography: Light exposure transfers patterns onto the photoresist.
Lithography is a critical step where the circuit pattern is transferred onto the wafer. The wafer is exposed to ultraviolet (UV) or extreme ultraviolet (EUV) light through a mask that contains the desired circuit design. The light causes a chemical change in the photoresist, allowing the pattern to be imprinted onto the wafer.
The lithography step plays a key role in determining the size and accuracy of the features on the microchip, from transistors to interconnects, making it central to the semiconductor industry’s drive toward smaller, faster, and more efficient devices.
4. Etching: Unwanted material is removed to create circuit designs.
After lithography, the wafer undergoes etching to remove the unwanted material and create the desired circuit structures. This process involves using chemical or plasma etching to selectively remove the exposed areas of the wafer, leaving behind the pattern defined by the photoresist.
Etching is critical for shaping the fine, detailed features of integrated circuits (ICs) and is used repeatedly throughout the fabrication process. There are two primary etching techniques used in semiconductor manufacturing: wet etching and dry etching. Each has unique characteristics, applications, and advantages, depending on the material to be etched and the precision required.
5. Ion Implantation: Ions are introduced to modify electrical properties.
Ion implantation involves introducing specific ions into a silicon wafer to alter its electrical properties. This process allows precise control over the concentration and distribution of dopants—impurities that change the conductivity of the semiconductor material, enabling the formation of regions such as n-type or p-type, essential for creating components like transistors, diodes, and other electronic devices.
Ion implantation offers several advantages over older doping methods, such as thermal diffusion, including greater precision in controlling dopant concentration and depth. As semiconductor devices become smaller and more complex, ion implantation has become an indispensable tool in fine-tuning the electrical characteristics of integrated circuits (ICs).
6. Packaging: The final chip is encased for protection and connectivity.
The final step involves packaging the semiconductor device. The individual chips are cut from the wafer and then encapsulated in a protective package. This package includes connections to external circuits and is designed to protect the chip from environmental damage and facilitate its integration into electronic devices.
As chip size decreases and performance requirements increase, packaging has undergone several technological innovations in the past few years. Some future packaging technologies and solutions include the use of deposition for traditional back-end processes such as wafer-level packaging (WLP), bumping and redistribution layer (RDL) technology, as well as etching and cleaning technologies for front-end wafer manufacturing.
These six steps are fundamental to the semiconductor manufacturing process, each playing a crucial role in creating the intricate and precise structures that make modern electronics possible.
