What is a silicon wafer? What is it used for?

• January 4, 2024
• WaferPro
• 0

It is possible that most people have come across and even used a silicon wafer in their day to day lives. It may not have been deliberate; however, for people who have utilized devices such as computers and smartphone, they have certainly used this equipment. As a leading silicon wafer supplier, we have been frequently asked "what is a silicon wafer?" "What are the uses of it?" In this article, we will give you a complete overview of silicon wafers.

For semiconductor device fabrication, MEMS, and more - we WaferPro supply the full spectrum of silicon wafer products including prime, test, and reclaimed grade silicon wafers available in a broad array of orientations, resistivities, thicknesses, and diameters.

Now let’s get into the details.

What Is A Silicon Wafer?

Silicon wafer is a material used for producing semiconductors, which can be found in all types of electronic devices that improve the lives of people. Silicon comes second as the most common element in the universe; it is mostly used as a semiconductor in the technology and electronic sector.

Most people have had the chance to encounter a real silicon wafer in their life. This super-flat disk is refined to a mirror-like surface. Besides, it is also made of subtle surface irregularities which make it the flattest object worldwide.

It is also extremely clean, free of impurities and micro-particles, qualities that are essential in making it the perfect substrate material of the modern semiconductors.

There are various methods used in silicon fabrication counting the horizontal Bridgeman method, horizontal gradient freeze method, vertical gradient freeze, vertical Bridgeman method and the Czochralski pulling method.

All through the growth process dopants can be included to modify the purity of the silicon wafer depending on its manufacturing purpose. The impurities can alter silicon electronic properties which are essential depending on the purpose of its production.

Some of the silicon dopants that can be added throughout the growth process include aluminum, boron, nitrogen, indium and gallium. A semiconductor can be regarded as either degenerate or extrinsic depending on the level the silicon wafer was, when the dopants were added.

During the fabrication process, degenerate semiconductors are mainly used as conductors due to the extreme levels of doping while extrinsic are lightly to fairly doped.

What Is The Silicon Wafer Used For?

1. Semiconductor

Even though other conductors are employed in more particular applications, silicon is the best and the most used semiconductor due to its extreme mobility both at high temperatures and at room temperature.

What makes Silicon an outstanding option in electronic devices is because its electrical currents can pass via the silicon conductors much quicker compared to other conductors.

2. Silicon Wafers In Electronic Devices

Semiconductors such as the silicon wafer can be used in the production of both chips and microchips in electronic gadgets.

Due to the uniqueness of the electrical currents via silicon wafers, these semiconductors are used in creating ICs (integrated circuits). The ICs act as commands for specific actions in various electronic devices.

The Silicon wafer is the main element in integrated circuits. Simply put, integrated circuits are a composite of a variety of electronic elements that are brought together to perform a particular function.

Silicon is the key platform for semiconductor gadgets. A wafer is just but a thin slice of the semiconductor material that acts as a substratum for microelectronic devices fitted in and above the wafer.

Even if it can be simple to relate silicon wafers with very particular technological devices that individuals only dream of, silicon wafers are way much closer than anyone may think!

Silicon wafers are used in computers, smartphones, and mobile devices and even in the tire pressure sensor system.

Manufacturing of the silicon wafer is an incredibly vital part of the establishment and expansion of a broad range of technological advancements.

3. Other Uses of Silicon Wafers

The ultra-pure silicon wafers offer a pristine canvas on which to fabricate the integrated circuitry central to all electronics. The uses include:

• Microprocessors - The central chips powering computers and smartphones
• DRAM & flash memory - Billions of silicon-based memory cells on chips
• CMOS sensors - Image sensors capturing light in smartphone cameras and more
• Power devices - Specialized designs managing electricity in systems
• MEMS - Tiny mechanical and electromechanical silicon systems
• Optical circuits - Waveguides and photonic devices integrate optics

How Silicon Wafers are Made - Step by Step

Silicon wafers are produced through an intricate process involving several steps. The majority of standard and custom silicon wafers from WaferPro are manufactured following these same strict processes under tight quality guidelines.

Silicon wafers are manufactured involving these several steps:

1. Growing the Ingot

   • High purity polysilicon is melted and grown into a single crystal ingot via the Czochralski process.
   • Ingots can be grown over 2 meter long and weigh hundreds of kilograms.
   • The ingot must have an exceptionally pure crystal structure to function properly in electronics. Impurities are extremely detrimental to performance.

2. Flat or Notch Grinding

   • With a nearly flawless silicon cylinder in hand, the next step is to grind flats or notches along the outside edge.
   • This helps properly align the ingot for the processes to follow. The orientation of the silicon crystal structure is crucial.
   • Like diamond cutters seeking the perfect plane to cleave a precious gem, silicon ingots must be sliced in alignment with the proper crystal face. The flats and notches provide fiduciary guides the cutting equipment can target.

3. Slicing

   • Ingots are sliced into discs 0.2mm to 1.5mm thick using an inner diameter saw or wire saw.
   • Hundreds of wafers can be sliced from one ingot.
   • The blades make initial passes, marking out circular wafers. Then thinner blades make finishing cuts along the markings, portioning individual wafers.

4. Edge Grinding

   • Yet before the wafers are ready for electronics fabrication, the edges get some attention. After slicing, the rims have microscopic cracks and fissures.
   • These get ground down in an edge grinding step. The periphery is smoothed over, removing any minute defects emanating from the cutting process.
   • This fortifies the edges and prevents further issues down the line. The wafers are then ready structurally but still lack the pristine surface needed by chipmakers.

5. Lapping

   • That flawless texture starts with lapping. Here the wafers get sandwiched between two rotating pads covered in abrasive particles and chemical slurry.
   • The setup is not too different conceptually from lapping valves on an engine.
   • The pads grind down peaks and valleys on both wafer faces until remarkably smooth and flat. But abrasives leave behind embedded contaminants.

6. Etching

   • Removing additional unevenness while simultaneously dissolving away microscopically clinging grit and particles.
   • For ultra high purity requirements, a sequence of etching and cleaning baths might be deployed, purifying the surfaces further through chemical interaction at the atomic scale.

7. Polishing

   • Sliced wafers are polished to achieve a mirror-smooth surface as free as possible of defects.
   • Polishing combines chemical effects with mechanical abrasion from soft pads rather than hard particles.

8. Cleaning

   • Wafers undergo wet chemical cleaning baths to remove contaminants.
   • Surface is prepared for subsequent fabrication processes.
   • The journey from silicon ingot to preliminary wafer is complete.

Quick Summary of silicon wafer manufacturing

Step	Description
1. Si silicon ingot	Grow a single crystalline silicon ingot using the Czochralski process
2. Flat or notch grinding	Grind flats or notches along the ingot edges to properly align for slicing
3. Slicing	Slice the silicon ingot into discs to produce raw silicon wafers
4. Edge grinding	Grind the edges of the sliced wafers to remove any cracks or fissures
5. Lapping	Use abrasive pads and slurry to flatten and smooth wafer surfaces
6. Etching	Use chemical baths to remove remaining unevenness and surface particles
7. Polishing	Apply final polishing to obtain extremely smooth and flat wafer surfaces
8. Cleaning	Thoroughly clean wafers to remove any remaining residues

Key Specifications of Silicon Wafers

Some key attributes considered when producing silicon wafers include:

• Diameter - from 1 inch to over 12 inches, most common sizes are 150mm, 200mm and 300mm.
• Thickness - typically 0.2-1.5 mm as mentioned.
• Flatness - critical dimension across the wafer, tolerance is under 1 μm.
• Surface finish - measured in variations over an area, target under 1 nm variation.
• Crystal orientation - atoms lined up to expose desired surface plane.
• Doping - intrinsic or with trace boron/phosphorus added.
• Defect density - minimized through tightly controlled processes.

Microprocessor Fabrication

To illustrate the full process, let's walk through how a microprocessor is fabricated on a blank silicon wafer:

1. A 300mm silicon wafer is prepared with desired crystal orientation and dopant polarity.
2. The critical transistor gates are defined with photolithography and etched on the surface.
3. Doping implants are precisely defined to create the source and drain regions.
4. Dielectric isolation layers are deposited between layers.
5. Several layers of transistors are stacked and wired to form logic gates.
6. Copper interconnects link devices across the chip.
7. Final passivation and testing completes the processors.
8. Individual dies are cut from the ~300mm wafer containing 1000s of chips.

So much functionality comes from remarkably intricate fabrication processes atop the foundation of a pure crystal wafer!

A Brief History of Silicon in Electronics

The electronics industry relies heavily on silicon, but this was not always the case. Early electronic devices mainly used bulky, power-hungry vacuum tubes that burned out frequently. The development of the transistor in 1947 marked a radical shift. These tiny semiconductor devices enabled far superior switches and amplifiers compared to tubes.

Silicon stood out among other semiconductors like germanium for its abundance, manufacturing capabilities, and electronic properties. Over decades, exponential advances enabled cramming more and more transistors into integrated circuits on silicon. This trend, known as Moore's Law, continues driving progress today.

Year	Milestone
1958	First silicon integrated circuit with four transistors
1968	First silicon DRAM memory chip
1971	First microprocessor with 2,300 transistors
1981	IBM introduces first personal computer with 29,000 transistor CPU
2012	Intel Ivy Bridge processor with 1.4 billion transistors

Moore’s Law has allowed incredible leaps in computation over six decades via ever-denser silicon circuitry. However, this relentless trend is approaching fundamental limits. Further breakthroughs in silicon technology remain critical, but many companies now explore alternatives like quantum and biological computing to continue advances when silicon reaches its apex.

Economics of Silicon Wafers

With strong demand growth for silicon chips powering new applications...

• Total silicon wafer market expected to reach nearly $17 billion by 2027
• Major wafer sizes transitioning from 200mm to larger 300mm
• Driving investments into larger wafers and fabrication plants

Advanced display and communications needs also push exotic compound semiconductor wafer markets (GaAs, InP) now surpassing $5 billion in annual sales. The simple but remarkable silicon wafer will continue to serve as the workhorse substrate for silicon microelectronics now deeply intertwined with modern society!

Silicon wafers serve as the critical base layer enabling production of integrated circuits and microchips that power electronics across every industry. As demand grows exponentially year after year for cheaper, faster, more powerful devices, so too does the skyrocketing worldwide output of these foundational semiconductor substrates.

In 2019, over 12 million silicon wafers emerged from fabrication facilities monthly. That translates to staggering annual production surpassing 150 million units globally!

Just five years earlier in 2014, wafer fabrication was nearly 100 million per annum. And by 2025, projections expect over 300 million wafers to roll off production lines annually as output steadily ramps up.

Driving massive growth is the relentless economic principle of smaller, faster chips. Each generation packs more computing power per surface area by shrinking component sizes. That means more dies fit per wafer.

This steady doubling over time, popularized as Moore’s Law, incentivizes ever increasing wafer supply to satisfy demand as costs drop per transistor. New iPhone or gaming console launches spark abrupt jumps in capacity requirements met through continually accumulating capital investment into new cleanrooms.

While early wafers spanned just an inch across, contemporary 300mm silicon discs enable immense economies of scale. New leading edge foundries are even piloting 450mm diameter prototypes.

Across the industry, fabrication floor space has expanded into millions of square feet containing tools costing up to $100 million each! Tech titans like TSMC and Samsung pooled over half a trillion dollars into wafer fabs this past decade alone as they race to intercept the next milestones in line width shrinking.

That furious capacity growth centered in Asia now sees leading pure play foundry TSMC exceeding 100 million wafer starts yearly. Samsung trails closely through their internal divisions churning out devices spanning memory to mobile chips. And SUMCO, GlobalFoundries plus Chinese players like SMIC combine for over 50 million more.

Blanket silicon wafer sales still represent a thriving $10 billion market feeding separate fab facilities demanding specialty designs. Market leader GlobalWafers ships over 2 million substrate units monthly as it scales to meet soaring demand.

This ballooning output lets the semiconductor firms embedding integrated circuits atop these flawless silicon and silicon-carbide platters sustain their staggering $500+ billion yearly revenues flowing across the worldwide supply chain.

So next time you marvel at the power behind your smartphone, consider the immense manufacturing prowess and capital underpinning those capabilities. Our digital future runs on the billions of silicon wafers churning through global fabrication pipelines annually!

Key Challenges Threatening Future Silicon Wafer Scaling

For over 50 years, silicon wafer improvements marched steadily in accordance with Moore's Law, doubling transistor counts every couple years. But as devices shrink towards atomic scale dimensions, severe manufacturing challenges loom menacingly, threatening to halt this relentless Pavlovian cadence of progress.

Lithography and Gate Patterning

photolithography. Silicon wafers in leading edge processes now pattern features smaller than the wavelengths of light used to expose them, pushing extremes of optical diffraction physics to maintain adequate fidelity and yield. Without a transition to costly and challenging next generation lithography techniques, this limitation of resolution predicts an end to optical lithographic scaling in the early 2030s at feature sizes around 5-3 nm.

Interconnect Bottlenecks

As transistor density increases, limitations shift to challenges fabricating the tiny copper wires interconnecting them across levels in the complex multilayer metal stack atop each substrate. Parasitic resistances and capacitances in these wires now dominate time delays and power consumption over the transistors themselves. Novel interconnect architectures and aggressive introduction of low resistance materials remain critical R&D pathways keeping scaling on track.

Economic Factors

The astronomical costs of next generation silicon substrate manufacturing facilities threaten upcoming nodes, with leading edge “fabs” now requiring investments of $10-20 billion. The tiny number of end customers capable of affording these costs squeezes out all but a few advanced logic and memory providers. Careful navigation of this unfavorable cost curve equation remains crucial for continuation of Moore’s Law through massive collaborative public-private research consortiums like IMEC, Applied Materials, TSMC, Intel, and Samsung.

Frequently Asked Questions

Where can I buy silicon wafers online?

Check out WaferPro's shop page where you can buy silicon wafers online. We have over 500,000+ wafers in our inventory. If you would like unique custom silicon wafers, you can request a custom quote here.

How many transistors are on a modern silicon wafer?

Leading edge wafers for processors like Intel's and AMD’s newest chips now cram over 100 billion transistors into a single silicon die thanks to fabrication processes with features between 5-7 nanometers across.

What’s the largest silicon wafer size used today?

While the industry standard remains 300mm (12 inch) diameter wafers, a few specialty foundries like TSMC are beginning to shift small production runs to larger 450mm wafers to improve economies of scale. However, extreme technical challenges around defect rates and fabrication equipment availability currently limit mainstream adoption.

How much does an individual silicon wafer cost?

Pricing varies tremendously based on wafer size, purity grades, surface finishing, fabrication processes, testing and more. But roughly, 200-300mm wafers range between $20 on the very low end up to $20,000 for highly exotic compound semiconductor configurations meant for specialized ASICs and space/defense applications.

How are completed silicon wafers turned into end consumer chips and electronics?

After the wafer fabrication finishes imprinting billions of electric components as integrated circuits on the silicon surface, individual dies get cut apart and go through extensive testing, inspection, packaging into protective shells, and final distribution to electronics manufacturers who incorporate them into finished products!

Could we build processors from something other than silicon in the future?

Research is intensely exploring new semiconductor materials like gallium nitride, carbon nanotubes, molybdenum sulfide and more. Each offers tantalizing advantages in charge velocity, thermal behaviors and computing potential. While silicon will surely continue dominating for decades longer, revolutionary new substrates will likely transform electronics again one day!

What could improve silicon wafer fabrication techniques moving forward?

Tremendous opportunities remain to enhance precision, scale and throughput across the entire wafer production pipeline. From purification and crystal growth, to slicing, polishing and inspection, we’re constantly chasing bigger wafers with smaller feature sizes and less defects through better lasers, chemical processes, automation and quality control. There’s vast room left for engineering innovation!