The functionality of virtually any modern-day device hinges on semiconductors. Also known as chips or microchips, a record-breaking 1.5 trillion semiconductors were sold in 2021. Additionally, in 2023, the global semiconductor market was valued at $611.35 billion and is expected to reach $2062.59 billion by 2032.
The rising use of electronics is a primary driver of this growth. The semiconductor manufacturing process has seven key steps, each requiring precision. One solution to help manufacturers meet this industry’s standards is the use of plasma. Discover the essential steps in this process and the various plasma applications for semiconductor packaging, cleaning and more.
Key Steps in the Semiconductor Manufacturing Process
Below are seven crucial steps involved in semiconductor manufacturing:
1. Design and Simulation
Chip design determines the performance of these devices. Design involves outlining the specifications for the chip’s system and architecture and the individual circuits’ layout, which is essential for sending, receiving, processing and storing the ever-expanding volumes of data for modern society. This intricate, cross-disciplinary process requires years of research and development, a significant investment, and a team of skilled engineers.
Researchers and engineers who develop semiconductors often use simulation software as part of their workflow. This software predicts how the chips will perform and identifies potential challenges, allowing these professionals to devise solutions that can prevent issues during production and save resources.
2. Wafer Production
Once the chip has been designed, manufacturing begins by purifying silicon, a semiconductor material, to create polysilicon. The purification process involves placing a seed crystal in molten silicon before slowly removing it. When the seed crystal is removed, atoms of silicon bond with the surface, creating single crystals of high-purity silicon known as ingots. These ingots are then sliced into wafers — which are thin discs with a diameter from around 1 to 12 inches — and polished to lift impurities.
3. Photolithography
In this step, wafers are coated with photoresist, a light-sensitive chemical. Next, the wafers go into a photolithography machine, exposing them to ultraviolet light via a patterned mask. The light travels through the cutouts of the mask, causing a chemical change that hardens the photoresist and embeds a pattern on the wafers. The unexposed photoresist is washed off, leaving behind the patterned layer that marks where components such as capacitors, transistors and resistors will be located.
4. Etching
The following step is etching, which removes the parts of the wafers that were not covered by the photoresist. This etching process creates complex patterns that will become the integrated circuits and can be done in one of two ways:
- Wet etching: The wafers get washed with chemicals to etch away the silicon.
- Dry etching: Manufacturers use gases such as plasma to produce the desired patterns.
5. Deposition
Next, deposition takes place, which involves applying a thin layer of conductive silicon dioxide to the wafer’s surface to build an insulating base. This layer protects the underlying layer of silicon from oxidization and possible contamination, making deposition vital in semiconductor manufacturing. The silicone dioxide also forms a surface for the following steps.
6. Ion Implantation
To create the electric components, like the transistors, certain parts of the wafer are doped with impurities to change their electrical properties so that they can either repel or attract electrons. Manufacturers introduce dopants like boron or phosphorus in the ion implantation process to define the microchip’s conductive insulating regions. They then bombard wafers with ions to achieve the necessary impurity.
Also referred to as diffusion, ion implantation begins with creating plasma, an ionized gas. This gas accelerates the ions of the required impurity, and these ions get sent toward the wafer to penetrate its surface, implanting themselves in the semiconductor material. The ions’ energy and the amount of time they interact with the chip determine how many ions get embedded and at which depth.
After ion implantation, manufacturers use physical vapor deposition and chemical vapor deposition (CVD) to deposit materials like insulators and metals onto the wafer’s surface. These layers then create the chip’s circuitry, building both the insulating layers and conductive paths. By repeating photolithography and etching, manufacturers can form several circuit layers, resulting in a more complex chip design.
7. Assembly and Packaging
In this step, the semiconductors’ various components are connected, assembled and packaged. First, metal wiring takes place, which involves depositing extremely thin metal layers on the wafer’s surface via electroplating, forming the electrical connections between the transistors. Manufacturers also use photolithography and etching to pattern the metal, building the required connections.
Next, manufacturers use a semiconductor lead frame during the assembly process. This thin metal structure connects the wiring from the chip’s surface to external electrical devices and circuit boards. The chips are placed on lead frames, and electrical interconnections are created by wire bonding them to the metal leads of the frame.
After this, the chips are covered in protective packaging, which is the final step in the manufacturing process. This packaging safeguards the integrated circuit from possible external threats and deterioration caused by time and facilitates the electrical connections that transmit signals to electronic devices’ circuit boards.
The Role of Plasma in Semiconductor Manufacturing
Plasma is essential in various steps of semiconductor manufacturing, especially for etching, deposition, packaging and cleaning processes.
What Is Plasma in Semiconductor Manufacturing?
Plasma is known as the fourth state of matter after solids, liquids and gases. It is a neutral ionized gas with free electrons and both positive and negative ions. Plasma is made when a gas is energized by an external energy source, resulting in one or more electrons being freed from an atom of gas. As a result of this process, ions and electrons are generated to form an electrically conductive material.
In semiconductor manufacturing, plasma has a variety of uses, such as reactive ion etching (RIE) and plasma-enhanced chemical vapor deposition (PECVD). These are some common plasma sources for semiconductor packaging, cleaning and other processes:
- Inductively coupled plasma: An induction coil generates an electromagnetic field to create plasma.
- Capacitively coupled plasma: Parallel electrode plates create plasma, providing greater control over the energies of ions.
- Electron cyclotron resonance: Magnetic fields increase plasma density, allowing for more exacting applications.
What Are Plasma Applications in Semiconductor Manufacturing?
Here are a few ways plasma is used in semiconductor manufacturing:
- PECVD: In the deposition stage, manufacturers use PECVD to deposit silicon nitride and silicon oxide films on the chip’s surface, creating insulating laters. Unlike traditional CVD methods that rely on heating devices, PECVD forms a film by converting the raw material gas into plasma via direct current, microwaves or radio frequency. As a result, PECVD can work with uneven surfaces and complex structures.
- Plasma dry etching: While wet etching was the conventional method, dry etching is considered mainstream today. Manufacturers can shape materials accurately at an atomic scale by using plasma to remove select parts of the wafers with techniques like RIE. This advantage can be key in overcoming challenges caused by scaling down to nanometer technology.
- Plasma cleaning: As microscopic contaminants could jeopardize the final product, semiconductor manufacturing demands highly sterile surfaces, which is where semiconductor cleaning companies play a role. Plasma cleaning for surfaces is an efficient method to remove organic residue before beginning steps such as wafer production, helping to ensure microchips are reliable and of high quality. Plasma cleaning is also suitable for sensitive components, such as the chips, before they are packaged. Semiconductor packaging plasma processing includes flip chip cleaning and wire bond preparation to remove oxides without affecting material performance.
Learn More About Using Plasma in Your Semiconductor Manufacturing Processes
Using plasma in the various steps of your semiconductor manufacturing processes, from sterilizing surfaces before production to packaging the devices, can help you overcome many industry challenges.
Surfx Technologies provides atmospheric argon plasmas, which are ideal for the high-volume manufacturing of semiconductor packages. By integrating quick treatment speeds, process adjustment and process logging, our cutting-edge automatic plasma machines produce high-quality products.
Request a demo to experience the difference of Surfx Technologies, or contact us today to learn more about our solutions.
