A semiconductor wafer is a thin slice of semiconductor substance, like crystalline silicon, used in electronics for the making of integrated circuits. In the electronics jargon, a thin slice of semiconductor material is called as a wafer. It could be a silicon crystal which is used in the making of integrated circuits and other micro devices.
Wafers are made up of very pure single crystal material. In the Czochralski process a cylindrical ingot of highly pure monocrystalline semiconductor like silicon or germanium is made by pulling of a seed crystal from a melt. Impurity atoms which are donors are added to the molten intrinsic material in exact amounts to ensure doping of the crystal. Thus changing the semiconductor into n type or p type semiconductor. The ingot is then sliced to form wafers.
If you are looking for wafers, check out WaferPro's extensive line of high-quality silicon wafers and semiconductor wafers manufactured with advanced semiconductor production techniques.
Silicon wafers are available in a variety of sizes in this case diameters. They are available from 25.4 mm to 450 mm. Semiconductor plants are known by the diameter of wafers they produce. The diameter of the wafers has increased through out to reduce costs with the current gen of fab considered to be 300 mm in diameter. If you are looking to buy silicon wafers online, you can check out our shop page here.
Wafers that are grown by making use of materials other than silicon will have different thickness from a silicon wafer. The thickness of the wafer is measured by the mechanical strength of the material used. The thickness of the wafer must be enough to support its own weight during handling.
Wafers that are under 200 mm diameter are cut into flats on one or more sides. Which indicates the crystallographic planes of the wafer. The earlier gen of wafers had a pair of flats that were placed at different angles which additionally conveyed the doping type. Wafers that are 200 mm in diameter make use of a single small notch to convey wafer orientation which gives no visual indication of the type of doping used.
Once when one or two flats are ground into the edge of the wafer, indicates crystal orientation which applies to wafers in some diameters. Flats are used to denote crystallographic and doping orientation. The red color represents material that has been removed. Wafers that are grown from crystals have a regular crystalline structure. Where silicon has a diamond cubic structure. this Silicon wafers are not made of 100% silicon. But are formed with impurity doping concentration in the initial stages. Carbon and other metallic contamination is kept to a minimum. Semiconductor doping is a process whereby the intrinsic semiconductor is changed to an extrinsic semiconductor. Extrinsic semiconductors are components of many electrical devices.
First and foremost, semiconductors themselves are materials that fall somewhere between conductors and insulators. This means they can act as both at times, switching between conducting electricity or providing resistance and acting as an insulator. The most common semiconductor materials used today are silicon and compounds made from elements like gallium or arsenic mixed together (referred to as III-V compound semiconductors).
Pure silicon and other semiconductor materials are not naturally good conductors - they need some modification first. This process is known as “doping” and introduces different impurity atoms to alter the semiconducting properties in useful ways for device functioning. Doped semiconductor materials make up the thin layers built upon the wafer surface.
Visit our online store to order your custom-specification semiconductor wafers and experience first-hand the pristine surfaces and precise tolerances resulting from WaferPro's sophisticated wafer fabrication process.
A bare semiconductor wafer starts as an extremely thin slice cut from a large single crystal ingot of an ultra-pure semiconductor material, typically silicon. Silicon ingots up to 450mm in diameter can be grown using something called the Czochralski process. The cylindrical ingots are then carefully sliced to get the thin circular wafers.
The size of wafers has increased over time, from earlier 25mm options to massive 300mm diameter wafers common in high-volume manufacturing today. Bare wafers are highly polished to an extremely flat and smooth surface. This is vital for later photolithography processes needing tiny component details etched at nearly atomic scale across the surface.
Today’s large wafers allow more dies per wafer ultimately bringing down costs. Even small increases in wafer size significantly increase yields thanks to the extra surface area.
Next let’s overview some key wafer characteristics and parameters:
As mentioned earlier, wafers are cut with specific crystal orientations including:
There are also some advanced wafer types including:
It's incredible to realize that such thin and physically fragile slices of material enable so much of our electronics-based world. Some key areas that depend critically on advanced IC chips built on semiconductor wafers include:
So while chips get most of the glory, we should recognize that none of them would even exist without the wonder that is the semiconductor wafer! The world economy depends critically on the excellent engineering and painstaking fabrication operations carried out on seemingly innocuous discs of silicon.
Semiconductor wafers form the foundation of integrated circuits and semiconductor devices. At WaferPro, we manufacture high-quality semiconductor wafers using an intricate multi-step process. Here, I’ll walk you through the key steps involved in transforming a raw semiconductor material into a polished wafer ready for device fabrication.
Ingot Growth - The process begins with crystal ingot growth. We place a small silicon seed crystal into a quartz crucible filled with molten polysilicon. As the crucible is slowly extracted from the molten silicon, the seed crystal acts as a template for the molten polysilicon to crystallize around into a large single crystal ingot up to 2 meters long. Precise control of temperature gradients and extraction rates allows us to grow almost perfect crystalline structures.
Slicing - The grown cylindrical ingot is sliced into thin discs using a specialized saw with a diamond-impregnated cutting blade. Hundreds of circular wafers can be obtained from a single ingot. During sawing, wafer thickness is precisely controlled to achieve uniformity and enable further processing steps. The wafers are typically between 500-900 microns thick at this stage.
Edge Grinding - Since the cutting process creates small cracks and defects around the wafer edge, the wafer periphery needs to be smoothed out. In the edge grinding step, we use grinding wheels to remove a narrow band of material from the edge until an undamaged, clean “new” edge surface is obtained all around the wafer circumference.
Lapping - Next, the wafer surface is globally planarized through a process called lapping. The wafers are allowed to slowly rotate between two rotating cast iron plates covered with an abrasive slurry. The plates grind away material from the front and back wafer surfaces until they are flat and parallel with each other. Lapping removes saw marks from wafer slicing and also sets wafer thickness close to the target thickness for device manufacturing.
Etching - After lapping, the wafers still have surface damage and contaminants embedded from previous processes. Etching is performed using wet chemicals (such as a mixture of hydrofluoric, nitric and acetic acids) which selectively and evenly remove a few microns from the silicon wafer surface while removing defects, leaving behind a pristine surface layer.
Polishing - At this point, the wafers undergo mechanical-chemical polishing using a silica-based slurry which oxidizes the silicon surface while abrasive particles together with a soft pad physically wear it away. This combined chemical and mechanical polishing produces extremely smooth and damage-free mirror-like wafer surfaces essential for photolithography and other downstream processes.
Cleaning - After polishing, wafers undergo rigorous cleaning in a series of wet chemical baths to remove particles, organic contaminants and metal impurities from wafer surfaces and maintain cleanliness standards. Various analytical techniques are also used to inspect, monitor and qualify the wafers prior to shipment to device fabrication facilities.
That super flat bare semiconductor wafer acts as the foundation for building up numerous layers of tailored materials intersecting in microscopic structures to create integrated circuits (ICs) through an intricate fabrication process known as microfabrication. This highly complex and sophisticated process imprints tiny electronic components and connections layered across the entire surface through steps like:
These steps along with others like cleaning and inspection are repeated across 25-100+ sequential processing steps working with remarkable precision. Slowly but surely, extremely intricate microscopic scale electronics components like transistors, capacitors, resistors and their interconnecting wiring build up across the wafer surface.
It’s through this sophisticated, extremely advanced microfabrication process that a bare semiconductor wafer gets transformed into a surface packed with fully functional circuitry - fulfilling the purpose that makes the wafer so vital to begin with!
The end goal is ultimately not the wafer itself - but what ends up constructed across its prepared surface. All the microfabrication produces many copies of a single type of integrated circuit design patterned repeatedly across the wafer, each copy called a die.
A single wafer can house anywhere from dozens to thousands of dies depending on:
At the leading edge, advanced processes allow packing over a thousand dies onto a single 300mm wafer!
The whole wafer gets sent through fabrication as a unit. But the end goal is all those individual dies packaging what becomes finished ICs once separated and housed in supportive casing. ICs are then put to use powering electronics through being integrated into devices or further circuit assemblies and components.
So in summary - a semiconductor wafer ultimately serves as the foundational platform holding microchips being constructed through intricately layering various materials to imprint integrated circuits which will be individually separated out later on.
The most common material for semiconductor wafers by far is silicon, making up around 95% of all wafers and ICs produced today. Silicon offers great semiconducting properties and abundance resulting in lower costs over other options.
Alternate wafer materials gaining increasing interest are compound semiconductors from mixtures of elements across the second and third rows of the periodic table. Referred to as II-VI and III-V compounds based on their make up, these compound semiconductor wafers provide wider options in tuning material properties.
Some emerging popular choices for certain applications are gallium arsenide (GaAs), gallium nitride (GaN) and indium phosphide (InP). Their tuned electrical behaviors can enable smaller, faster and more efficient devices. However wafer sizes max out much smaller and costs run higher than ubiquitous silicon.
Silicon carbide wafers also find niche uses when high heat tolerance, voltage handling or other specialized parameters take priority over mainstream requirements met easily with silicon.
There’s still much active research pushing semiconductor wafer innovations further to extend abilities in what integrated circuitry can achieve. Milestones seem to come surprisingly regular still thanks to scientific creativity finding ways to circumvent apparent barriers.
Recent years have seen multiple revolutionary breakthroughs already in wafer scale endeavors, like:
And many more wafer focused developments targeting better efficiency, density, speed, connectivity capacities and capabilities seem poised to nurture continued progress in semiconductor accomplishments.
Which all emanates from the thriving ecosystem seeded around these seemingly simple but technologically mighty semiconductor wafers! Their durable reign as the bedrock of integrated circuit innovation continues opened up to encouraging new possibilities ahead.
Nearly all modern electronics require integrated circuits imprinted onto raw silicon. Smartphones, computers, appliances, vehicles - semiconductor wafers power them all!
We have wafers to thank for technologies that enhance every aspect of society:
Blazing fast 5G networks rely on RF chips built from silicon. Without wafers, we’d still be using wired telegraphs!
GPUs for gaming, video processing chips for streaming shows, audio codec chips for music - all demand advanced semiconductor chips.
Space agencies use rugged semiconductor wafers due to their durability and radiation resistance. Good luck exploring Mars without them!
Solar panels, wind turbines, electric vehicles, smart power grids - semiconductor wafers drive greener technologies.
Wearable medical devices, precision drug delivery systems, MRI machines, and other life-saving technologies depend on sophisticated silicon microchips.
The semiconductor industry amazingly keeps finding ways to pack more and more devices into smaller spaces on chips. And since a single wafer contains many identical chips, the value that can be created from one wafer is enormous. However, we are approaching fundamental limits of physics and economics:
|Feature size limits
|Novel nanomaterials, 3D chip integration, advanced packaging
|Soaring fab costs
|Modular equipment, multi-chip technologies
Nevertheless, the industry has a great history of overcoming barriers, and semiconductor wafer technology still has a very exciting future ahead! With processors now permeating virtually all advanced products, humanity is incredibly dependent on the innovations coming from those glossy silicon discs that enable our digital world.
The most prevalent material used is silicon, accounting for over 90% of all wafers produced. Other materials like gallium arsenide, silicon carbide and gallium nitride are used for specialized high-performance applications.
Common wafer sizes range from 100-450 mm in diameter. State-of-the-art fabs now use 300mm wafers, which allows more chips per wafer. The industry is actively developing 450mm wafers for future high-volume manufacturing.
Wafer thickness depends on the material and application, but they are typically hundreds of microns thick. Silicon wafers can range from roughly 100-1000 microns (0.1-1.0 mm). This incredibly small thickness uniformity facilitates nanoscale device fabrication across the entire surface.
Major wafer suppliers include companies like Shin Etsu, SUMCO, GlobalWafers and SK Siltron. Many semiconductor manufacturers also produce some portion of their own wafers internally.
Modern microprocessors can require 500 or more fabrication steps! This includes growing the crystal ingot all the way through slicing wafers and processing them into finished chips suitable for packaging. The complexity of designs requires an intricate dance of deposition, lithography, etch, implant, polish and inspection steps repeated sequentially.
Wafers move through the fab either manually by operators wearing specialized protective equipment or by automated material handling systems. Care is taken to avoid any contamination or damage during both automated and manual transport.
So in summary, semiconductor wafers come in different sizes and materials, are extremely thin and pure, and go through an immense number of complex processing steps in order to build the advanced ICs that drive progress in electronics!
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