A silicon wafer manufacturer might mention that they incorporate gettering into their processes. What is gettering? It’s a step that removes impurities from a silicon wafer. Typically, this step occurs during the crystal growth process or as a facilitator for VLSI manufacturing. Gettering involves several steps. This article will briefly cover why gettering is important.
The Importance of Gettering
As you can imagine, silicon wafers are highly sensitive components that require care and attention to detail before they are used for electronic device manufacturing. Extrinsic gettering is employed to create a form of stress on the silicon wafer, which brings out the impurities of the material that are later removed.
The presence of impurities is among the leading cause of silicon wafer failure. They can adversely affect conduction, compromising printed circuits in the process. An impurity can also become a hindrance to the wafer polishing process. Inconsistencies in a wafer’s composition can create a defect, ultimately leading to the failure of an electronic device or semiconductor.
Gettering also has its advantages, as it removes any excess gases that might be present in the wafer material. Even the minutest amounts of gases can cause unstable conduction. Therefore, the gettering process is critical in removing any factors that might damage the wafer.
An impure wafer can mean the difference between success and failure. When consulting with your silicon wafer manufacturer, it is crucial to ensure that they include gettering as part of their services.
Silicon wafers form the foundation of electronics manufacturing. Almost every electronic device that you use today uses them. As such, it is helpful to learn about silicon wafer polishing and the cleaning process.
Silicon wafers are very sensitive pieces–they can be contaminated simply by being exposed to air. As such, cleaning the wafers is an indispensable step in the manufacturing process. Thanks to standardization, there is an industry-recognized, three-step process for cleaning. We will summarize it here.
The Cleaning Process
The first step is solvent cleaning. The wafers are dipped in acetone to eliminate oils and contaminants. Then, the wafers move to a container with methanol. The first step involves two liquids because the solvent (acetone) can leave a residue that might contaminate the wafer. Methanol removes leftover residue.
After getting rinsed with DI water and blow-dried with nitrogen, the wafer undergoes RCA-1 cleaning. This step oxidizes the wafer. The RCA-1 solution is a mixture of ammonium hydroxide and DI water.
Finally, the wafers are placed in a hydrofluoric acid dip. The acid dip removes the oxidized layer formed form the second step. Hydrofluoric acid is highly volatile, so the step requires protective equipment.
This standardized cleaning procedure purges the wafer of contaminants, ensuring they are ready to proceed with the manufacturing process. Many wafer manufacturing firms offer this service as part of their silicon wafer polishing solutions.
The pick and place system is the backbone of silicon wafer manufacturing. As the demand for semiconductors and microchips increases, the rise of automation has been crucial for production facilities. This post will briefly discuss the general components of a pick and place line.
How Pick and Place Operates
The pick and place system has been utilized in the technology manufacturing industry since the 1980s. As technology progressed, these systems also became more complex. Thanks to these advances, the pick and place method makes it possible for large quantities of silicon wafers to be manufactured.
Aside from the potential for mass production, pick and place systems are important because they minimize the chances for manufacturing errors or defects. This allows companies to maintain productivity and minimize waste.
Cameras, imaging technology, and robotic arms form the foundation of pick and place systems. The cameras can monitor wafers at each step of the production process. It will approve or reject batches of wafers based on the criteria that the operator programmed. Robotic “picks” use vacuum technology to move quantities of wafers from one manufacturing station to another. The wafers go through each production step until they are ready for final inspection and shipping.
With pick and place technology, wafer manufacturing companies have a powerful tool in making tomorrow’s electronics. Many wafer polishing companies might use this system in their various services.
A prevailing trend in the technology manufacturing industry is the need for smaller, thinner silicon wafers. Although the conventional diamond grinding and laser processes do well in preparing wafers, these methods still have limits.
A side effect of the wafer grind process is damage to the subsurface. This can compromise the composition of a wafer, and these imperfections need to be removed. Silicon wafer polishing addresses this issue and allows for thinner, stronger, and more robust products.
How Silicon Wafer Polishing Works
Silicon wafer polishing, also known as Chemical Mechanical Planarization, is a process that removes the peaks and valleys associated with subsurface damage. It also removes stress and surface damage.
Polishing works by putting vacuum pressure on a wafer. It is slowly put in contact with a rotating platen that is fitted with a polishing pad. Meanwhile, a diamond liquid slurry is sprayed on the polishing surface. Together, the polishing pad and slurry grind away imperfections. The silicon wafer polishing process can remove between 5 and 10 microns from a wafer.
Often, silicon wafer polishing is a post-process step that takes place after back grinding. This step is often necessary in order to create more powerful microchips or other electronics.
Many technology manufacturing companies utilize wafer polishing as part of their everyday operations. As the development of more complex electronics increases, the demand for this service will also increase.
Surprisingly, complex computer chips are made from something quite technically unimpressive: sand. Microprocessors are one of the most complicated products to manufacture, and creating these chips is a difficult and precise process. The steps, from isolating silicon from sand to silicon wafer dicing to layering interconnects, are the most basic stages in an amazingly sophisticated fabrication process.
Start With Sand
The process of creating a computer chip begins with silica sand, comprised of silicon dioxide. Silicon is the base material for semi-conductor manufacturing and must be isolated from the sand and pure before it can be used in manufacturing.
Multiple purification processes are performed to deliver electronic-grade silicon. A purified silicon ingot weighs around 100kg and is made ready for the next step.
Silicon Wafer Dicing
The circular silicon ingot is sliced into wafers as thin as possible. The silicon wafers are then refined and polished to provide the best possible surface for the next fabrication steps.
A layer of photoresist is spread thinly across the wafer, and this layer is then exposed to a UV light mask shaped in the pattern of the microprocessor’s circuits. The exposed photoresist becomes soluble and is washed off by a solvent. A pattern of hard material is applied to the wafer creating thin silicon ridges.
Using a process as complex as silicon wafer dicing, an insulation layer is applied to the surface, and holes are etched into it. Electroplating is used to deposit copper ions on the surface, forming a layer of copper on top.
The transistors are now connected in an architecture that allows the chip to function as a processor.
Test and Sliced Dies and Packaging
The chips are now ready to be tested, and the wafer is sliced into dies. Dies are packaged and assume the familiar form factor of a desktop processor. Processors are then tested for power efficiency, frequency, and other performance metrics.
Silicon is an extremely common element on Earth and is responsible for inviting white sand beaches, as silica, an oxide of silicon, is the most common component of sand. Modern computing also owes a lot to silicon, as it is a crucial component in microelectronics and computer chips. A silicon wafer manufacturer provides silicon wafers that are used as a part of the original manufacture of coordinated circuits or similar gadgets.
As silicon wafer manufacturers have shown that silicon has many other practical uses as well. Silicon is neither metal nor non-metal; it’s a metalloid, an element that falls somewhere between the two. Metalloids generally have properties of both metals and non-metals. Silicon is a semiconductor, meaning that it does conduct electricity.
The Hotter, the Better
Unlike a typical metal, silicon gets better at conducting electricity as the temperature increases (metals get worse at conductivity at higher temperatures). This is why there are many silicon wafer manufacturers that supply the market.
As a semi-conductor, silicon is used to make transistors, which amplify or switch electrical currents and are the main elements in electronics from radios to iPhones. These manufacturers look to silicon wafer manufacturers as a key supplier.
Silicon is also used in a variety of ways in solar cells and computer chips, for example, as a metal-oxide-semiconductor field-effect transistor, or MOSFET, the basic switch in many electronics.
Silicon also has future potential in the creation of tiny lasers called nanoneedles, which can transmit data faster and more efficiently than traditional optical cables. Superconductor lasers shed heat much easier than glass lasers, meaning they can create more power than traditional lasers.
Silicon must turn into a wafer before silicon wafer polishing and before a semiconductor can be built. This process begins with growing a silicon ingot. Growing a silicon ingot can take anywhere from one week to one month, depending on a variety of factors, including quality, size, and the specification. Here’s a closer look at silicon wafer processing and precisely how they are made.
The first step to grow an ingot is to heat the silicon to 1420°C. This is above the melting point of silicon and long before silicon wafer polishing. Once the dopant combination and polycrystalline has been liquefied, the seed, a single silicon crystal, is positioned on top of the melt, barely touching the surface. The seed has the same crystal orientation required in the finished ingot.
After the ingot is fully-grown, it is ground down to roughly a diameter that is slightly larger than the target diameter of the final silicon wafer. After being passed through several inspections, the ingot goes to slicing next. With silicon wafer polishing not far off, the silicon is sliced. Due to the silicon’s hardness, a diamond edge saw is needed to carefully slice the silicon wafers to a width slightly thicker than the target specification.
The final and most critical step in the manufacturing process is silicon wafer polishing. This process takes place in a cleanroom. To maintain cleanliness, workers must wear cleanroom suits that cover their bodies and do not collect any particles. They also stand under a fan that blows away any small particles that might have accumulated before entering the room.
Pick and place automation systems are commonly used in modern manufacturing because they speed up the process of picking up items or parts and placing them in other locations, and automating this process can significantly increase production rates. The robots in a pick and place system handle repetitive tasks and free up human workers to focus on the more complex processes and work.
Pick and place robots are usually mounted on a stable stand and positioned to reach different areas to perform work. They have advanced vision systems that allow them to identify, grasp, and move objects from one place to another. With many design options available, pick and place system robots can be configured with various tooling options for the ends of their arms, which can be used in different applications, such as assembly, packaging, or bin picking.
Applications for Pick and Place Systems
Pick and place robots are also used in applications such as bin picking, packaging, and inspection. Here are a few of the most common applications for pick and place system robots.
Assembly – Used to grab incoming parts from one location, and place or affix the part on another piece of the item before it is transported to the next assembly area.
Packaging – Pick and place system robots grab items from an incoming source or area and place the items in a packaging container.
Bin Picking – Here, they grab parts or items from bins. Advanced vision systems help them to distinguish shape, color, and size to pick the right items from bins of randomly mixed items.
Inspection – Advanced vision systems allow them to pick up objects, detect anomalies, and remove defective items or parts.
One of the most significant advances in electronics manufacturing is silicon wafer dicing. Wafers form the basis of semiconductors, microchips, and many electronic devices. To provide a general overview of the process, dicing involves high-speed saws that cut precise dies from the silicon wafer. The resulting dies are then placed in printed circuit boards or another electronic device.
Wafer dicing is an automation-focused process, as the cuts for wafers need to be made to exacting specifications. Many dies find purpose in computers, and also in sophisticated machinery used in the medical and defense industries.
One process, known as “high-precision wafer dicing,“ involves the cutting of silicon wafers to very small sizes. High-precision production methods can craft silicon dies for devices as little as 0.2mm. The wafers used in these manufacturing procedures can be as thin as 0.02mm
Silicon wafer dicing uses two machines to make die cuts. One method might utilize dual saw blades. Another might use a laser to etch out the dies. No matter the process, all steps must be overseen by computers to ensure accuracy and consistency. Another inspection crew conducts the final inspection to verify the dies. Diced wafers that do not pass inspection may be sent for reclaiming so that the materials can be used in another product.
Silicon wafer dicing utilizes advanced technology to create the innovations of tomorrow. Contact an experienced polishing company to learn about their dicing capabilities.
Silicon wafers are the building blocks of computer chips, circuit boards, and many electrical devices. While silicon is an exceptional material, it has limitations. Given the precise and exacting production standards of the manufacturing industry, it is not uncommon to have many wafers get rejected daily.
That doesn’t mean erroneous batches can never be reused, however. Many polishing companies offer wafer reclaiming services. This is a process that takes off layers of silicon to create a like-new service. This allows the wafers to be used in other projects instead of immediately filling a scrap heap. The wafer reclaiming process has several steps:
- Incoming Inspection
- Stripping and Etching
- In-Process Quality Assurance
- SC1/SC2 Clean Spin/Rinse/Dry
- Visual Inspection
- Final Inspection and Quality Assurance
Polishing companies will accept a batch of rejected wafers and inspect them to determine if they are salvageable. When they have been approved, they go through the procedure. Reclamation uses a combination of polishing and chemical processes to remove old films and etchings. Then, the batch goes through a final inspection before being re-issued for another production run.
Refurbished silicon wafers will be thinner than their new counterparts. However, they can still find use in other applications. When refining your initial production processes at your facility, you may want to consider wafer reclaiming services that can give rejected runs a new purpose.