10 Questions You Should to Know about Silicon Carbide Filter

Silicon carbide is an excellent material that is reshaping the future of multiple industries. Are you interested in this material? Read on to learn everything about silicon carbide.

If you want to learn more, please visit our website HEBEI CANGCHEN.

Quick Links

1. Introduction to Silicon Carbide
2. Silicon Carbide Manufacturing Process
3. Silicon Carbide Performance Characteristics
4. Comparison of Silicon Carbide with Other Materials
5. Uses of Silicon Carbide
6. Future Prospects and Market Trends of Silicon Carbide Materials
7. Silicon Carbide Buying Guide

If you don’t have time to read a lot of text, we have compiled some common questions from users for you, hoping to help you quickly!

1. FAQs.

Introduction to Silicon Carbide

Definition and Chemical Structure

The chemical formula of silicon carbide is SiC, which is composed of a silicon atom and a carbon atom precisely bonded together. People also call silicon carbide “black diamond”. It is a material with ultra-high hardness and high thermal conductivity.

Historical Discovery and Development

Are you curious about how silicon carbide was discovered? In , American inventor Acheson accidentally discovered silicon carbide when he was trying to make diamonds in the laboratory.

Since its discovery, silicon carbide has undergone an important transformation from a simple grinding material to a high-tech semiconductor material. With the continuous improvement of manufacturing technology, the application field of silicon carbide is also expanding.

Natural and synthetic silicon carbide

You may wonder, does silicon carbide exist in nature? The answer is yes. Natural silicon carbide is mainly found in the rare mineral moissanite, but the content is very small. Currently, 99% of the silicon carbide you see on the market is artificially synthesized, which is a stable supply channel for silicon carbide.

Silicon Carbide Manufacturing Process

Traditional production methods

Lely method

Are you curious about how high-purity silicon carbide is produced? The Lely method is one of the most classic manufacturing methods.

1. Heat silicon carbide powder to ℃

2. Sublimate graphite in a crucible

3. Crystallize on a graphite rod at a lower temperature

The purity of silicon carbide crystals obtained by this method is very high, but the cost is also high.

Chemical Vapor Deposition (CVD)

CVD is the most commonly used method for preparing semiconductor-grade silicon carbide.

1. Introduce a special gas mixture into a vacuum environment

2. Make the gas react chemically on the substrate surface

3. Form a high-quality silicon carbide film

This method can accurately control the growth process of silicon carbide and is very suitable for large-scale production.

Modern manufacturing technology

With the advancement of modern science and technology, traditional processes have been improved, manufacturing costs have been greatly reduced, and the quality of silicon carbide obtained has become higher. The main improved technologies are in two aspects.

1. Use an improved temperature control system

The temperature can be accurate to 1°C, which is more accurate;

Multi-segment temperature gradient control can be used, which is more efficient and reasonable;

With real-time temperature detection and feedback, it can ensure that the crystal growth process is more uniform and stable.

2. Introduce intelligent automation control

Use AI to assist production control

Use robots for crystal pulling

After experience testing by many manufacturers, the production efficiency has increased by 300% and the defect rate has decreased by 50% compared with traditional processes

3. New growth technology

Physical vapor transport (PVT)

Continuous feed sublimation method

Improved Lely method

Through the improvement of modern technology, you can get higher quality silicon carbide at a more favorable price. So far, the manufacturing cost of the market has dropped by 40% compared with 5 years ago, and the quality has doubled!

Quality Control and Standards

In the production process, quality control is crucial. Are you curious about what kind of silicon carbide is good? What quality control does high-quality silicon carbide go through during the production process?

Crystal quality inspection

X-ray diffraction analysis;

Microscopic observation of crystal orientation;

Dislocation density test results show that the defect density must be less than 1/cm2

Purity test

Chemical composition analysis;

Impurity content test;

Atomic spectrum analysis. If it is semiconductor-grade silicon carbide, the purity must reach 99.%

Performance verification

Breakdown voltage test

Carrier mobility test

Test whether the thermal conductivity meets the standard

International standard certification

SEMI standard

JEDEC certification

ISO quality system to ensure product quality

Through these strict quality assurances, you can ensure that the silicon carbide you receive is of high quality. Did you know that high-quality silicon carbide products can only enter the market after passing all tests?

Silicon Carbide Performance Characteristics

Mechanical Strength

Silicon carbide is second only to diamond in hardness, making it a very hard material, which is why you can find it in a variety of cutting tools.

• Mohs hardness 9.5
• Compressive strength MPa
• Flexural strength 550MPa

Thermal Conductivity

Silicon carbide also performs well in heat dissipation, and it is an effective material for dissipating heat from your electronic devices.

• Thermal conductivity 120-270 W/mK
• Thermal expansion coefficient 4.0×10^-6/°C

Electrical Properties

Silicon carbide is also an excellent semiconductor material with unique advantages.

• High breakdown voltage (10 times that of silicon)
• Low on-resistance
• High frequency working capability

Chemical Stability

Silicon carbide is chemically very stable and not easily corroded, making it very suitable for some chemical applications.

• Acid and alkali corrosion resistance
• Strong oxidation resistance
• Good chemical inertness

Corrosion Resistance

In harsh environments, silicon carbide still performs well. It has excellent corrosion resistance and long service life.

• High temperature corrosion resistance
• Chemical corrosion resistance
• Strong wear resistance

Semiconductor Properties

By doping, you can get different types of semiconductors:

• N-type: doped with nitrogen or phosphorus
• P-type: doped with boron or aluminum

Comparison of Silicon Carbide with Other Materials

Silicon Carbide vs Silicon

Compared with traditional silicon materials, silicon carbide has the following advantages:

Three times the bandgap width

10 times higher breakdown voltage

Higher operating temperature

Similarly, silicon carbide also has disadvantages:

production costs are 3-5 times higher;

wafer defect rates are higher;

processing technology is more complicated

Silicon Carbide vs Aluminum Oxide

Compared with alumina, which is also a ceramic material, it has the following advantages:

Higher thermal conductivity

Better electrical conductivity

Stronger high temperature resistance

Compared with aluminum oxide, silicon carbide has the following disadvantages:

Higher cost

More difficult to process

More demanding manufacturing process requirements

Learn more: Silicon Carbide vs Aluminum Oxide

Silicon Carbide vs Gallium Nitride

Compared with gallium nitride, the advantages of silicon carbide are as follows:

Better heat dissipation performance

More mature technology

Higher reliability

In comparison, the disadvantages of silicon carbide are:

Poor high-frequency performance

Larger volume

Uses of Silicon Carbide

Traditional Industrial Applications

Traditional applications have laid a solid market foundation for silicon carbide. Did you know that more than 60% of silicon carbide is used in these traditional fields every year? Whether it is cutting tools, refractory materials, or automotive parts, silicon carbide can be seen in many common applications in daily life, thanks to its excellent performance and durability.

Abrasives and cutting tools

In traditional industrial applications, silicon carbide is the most widely used in the field of abrasives. Every year, 40% of the world’s silicon carbide is used for abrasive manufacturing. It has high hardness and sharp cutting edges. It is an indispensable material in the grinding and cutting industry. If you are choosing a suitable cutting tool, silicon carbide is the material you can give priority to!

• Sandpaper manufacturing

Black silicon carbide is suitable for grinding hard materials such as glass, ceramics and other materials

Green silicon carbide is suitable for precision polishing to create a perfect surface finish

• Abrasive tool production

Manufacturing of grinding wheels and discs

High-precision grinding tools

• Sandblasting

Hard metal surface treatment

Hard stone surface processing

Refractory materials

Silicon carbide has excellent high temperature resistance. Many high temperature industries cannot do without silicon carbide. According to empirical statistics, the service life of silicon carbide is 3 times that of ordinary refractory materials. It can effectively help you save costs.

• Metallurgical industry

Blast furnace lining

Smelting crucible

Refractory bricks

• Heat treatment equipment

Annealing furnace parts

High temperature furnace tubes

• Heating elements

Kiln components

Roller kiln accessories

Sintering furnace parts

Automotive parts

Many properties of silicon carbide meet the needs of modern automobiles and are widely used as important automotive parts. Using silicon carbide as a part can increase its life by about 50%.

• Braking system

Brake pad material

Brake disc coating

Clutch plate

• Engine parts

Mechanical seals

Bearing materials

Piston rings

• Transmission system

Gear coating

Gearbox components

Jewelry and decorative uses

You may not think that silicon carbide can also be made into artificial gemstones as a substitute for diamonds. Its price is only 1/10 of that of diamonds, but its hardness is close to that of diamonds. It is a cheap substitute for diamonds in some applications.

• Artificial gemstones

Moissanite jewelry

Cutting and processing

Surface treatment

• High-end decorations

Watch faces

Jewelry inlays

Artwork production

Advanced technology applications

Advanced technology applications

In addition to traditional industries, silicon carbide can also be used in some advanced technology fields, such as the semiconductor industry, electric vehicles, military aerospace, etc. Silicon carbide is developing rapidly in these industries, with an annual market growth rate of more than 35%. Does your industry also benefit from silicon carbide technology? Below we will give you a detailed introduction to the applications and advantages of silicon carbide in these industries.

Semiconductor Industry

Did you know? Silicon carbide is quietly changing the entire semiconductor industry。

Power electronics — a new generation of power devices:

• Power MOSFET

Breakdown voltage exceeds 10kV

Conduction loss reduced by 50%

Switching frequency increased by 10 times

• Schottky diode

Small reverse leakage current

Fast switching speed

Good temperature stability

• Power module

Volume reduced by 300%

Efficiency increased by 30%

Excellent heat dissipation performance

High temperature electronics — the best choice for extreme environments:

• Aerospace

Engine control systems

Flight controllers

Sensor modules

• Industrial applications

Deep well drilling equipment

High temperature sensors

Industrial furnace control, the operating temperature can reach 400℃, and its life span is 3 times that of traditional devices.

The electric car revolution

Power conversion system — effectively improve the performance of electric vehicles:

• Main drive inverter

Efficiency increased to 99%

Volume reduced by 60%

Weight reduced by 50%

• DC-DC converter

Power density doubled

Heat generation reduced by half

Reliability improved

• On-board charger

Charging speed increased by 40%

Miniaturized design

Heat dissipation optimized

Battery management — intelligent management system:

• Battery protection

Overcharge protection

Over discharge protection

Temperature monitoring

• Energy optimization

Balanced charging

Efficiency improvement

Life extension

Renewable Energy

Solar inverter — the core of photovoltaic power generation:

• Grid-connected system

Conversion efficiency 99%

Volume reduction 50%

Optimized heat dissipation performance

• Off-grid system

Improved stability

Reduced maintenance costs

For more Silicon Carbide Filterinformation, please contact us. We will provide professional answers.

Further reading:
Heavy Duty Bar Grating Specification Criteria - Grating Pacific

Extended service life

Wind power generation — high power application:

• Converter

Increased power density

Enhanced reliability

Optimized efficiency

• Grid-connected equipment

Good grid adaptability

Low harmonic content

High control accuracy

Military and Aerospace

Armor Systems — A new generation of protection:

• Lightweight armor

40% lighter

Improved protection

Cost-effective

• Composite armor

Multi-layer protection

Strong impact resistance

Easy maintenance

Future Prospects and Market Trends of Silicon Carbide Materials

As an excellent advanced material, silicon carbide has shown great potential and value in more and more fields. Whether from 5G to new energy, or from environmental protection goals to manufacturing process innovation, silicon carbide is ushering in a golden period of development in modern times. We will analyze and discuss its future development prospects and market trends for you from multiple dimensions.

Emerging Applications

Silicon carbide is constantly exploring new applications in emerging fields, and its various advantages are recognized by many high-tech fields. According to market research institutions, by , the size of the silicon carbide-related market will exceed US$5 billion. If the opportunity is seized, it will become a key driving force for many industries.

6G communication equipment:

Silicon carbide’s high frequency and high power performance are very suitable for 6G base station core components. It is one of the ideal materials and can bring higher speeds and lower latency.

Smart grid:

In power electronics applications, silicon carbide devices effectively reduce energy loss and improve the efficiency and stability of power systems, which greatly promotes the popularization of smart grids.

Quantum computing:

SiC crystals are expected to become a hot research material in the field of quantum computing because of their extraordinary potential in applications in quantum dots and spin qubits.

Market growth forecast

Silicon carbide is showing an unprecedented strong growth trend in the market. The following is the data we have collected for your reference:

The compound annual growth rate (CAGR) is 35%: Demand is surging, especially in areas such as power electronics, automobiles and new energy.

Electric vehicle market: Silicon carbide devices can provide significant energy efficiency and endurance for electric vehicles, and its market share is predicted to double in the next five years.

Demand for new energy: With the development of new energy, the demand for high-efficiency power conversion devices in wind and solar power generation equipment is increasing, which has promoted the popularization of silicon carbide, brought opportunities to investors, and further established the position of silicon carbide materials in emerging technologies.

Research and Development

Innovation is the core driving force for the development of silicon carbide. Global research and development continues to increase, especially in the following aspects:

Emerging manufacturing processes: such as low-cost large-scale single-crystal silicon carbide growth technology, which can promote the large-scale application of silicon carbide materials.

Improved material performance: Nanostructure optimization and doping process improvements can further enhance the stability of silicon carbide in extreme environments such as high temperature and high pressure.

Costs continue to decline: With the continuous advancement of production technology, the manufacturing cost of silicon carbide is decreasing year by year, which provides a solid foundation for more extensive commercial applications.

Environmental impact

Silicon carbide is a relatively green material and is of great significance to the global green development. If you are an environmentalist, the following data is what you want to see:

Reduce energy loss by 30%: Compared with traditional silicon-based materials, some devices made of silicon carbide have greater advantages in energy conversion efficiency.

Reduce carbon emissions by 40%: Silicon carbide reduces a large amount of greenhouse gas emissions through its application in electric vehicles, smart grids and other fields.

Improve resource utilization: The high efficiency of silicon carbide can improve the unit resource utilization of equipment and save costs, which also makes silicon carbide an important driving force for the global carbon neutrality goal.

Cost analysis and economic benefits

Silicon carbide not only has excellent technical performance, but also has a significant effect on economic benefits. This is the experience gained by a company after using silicon carbide devices:

Equipment life is extended by 50%: The durability of silicon carbide greatly reduces the frequency of equipment replacement.

Operation cost is reduced by 25%: Due to the reduction of energy loss and the improvement of efficiency, the overall operation cost of the equipment is reduced.

Silicon carbide materials not only have excellent technical performance, but also have significant economic benefits.

System efficiency is improved by 35%: Whether it is power transmission or industrial automation, silicon carbide materials can significantly improve the efficiency of the system.

Silicon Carbide Buying Guide

In order to help you choose the most suitable silicon carbide products for your industry, we have prepared the following comprehensive purchasing quality for you, from selection standards to quality certification, to help you choose the most suitable product for yourself.

Selection criteria

When purchasing silicon carbide products, you can focus on the following core standards.

Purity grade requirements:

High purity (>99%), suitable for high-tech fields such as semiconductors and electronics.

Medium and low purity, mainly used in industrial applications such as refractory materials and abrasives.

Working temperature range:

You need to choose the most suitable high temperature resistant silicon carbide product according to your specific application.

Industrial heating equipment needs to withstand temperatures up to ℃.

Automobiles and electronic equipment need the stability of frequent switching between high temperature and normal temperature.

Application scenario matching:

You also need to choose the material form of silicon carbide according to the specific application scenario, for example:

Abrasive: granular silicon carbide.

Refractory material: block or brick-shaped silicon carbide ceramics.

Semiconductor: high-purity single crystal silicon carbide.

Quality Standards

High-quality silicon carbide products must comply with the following industry standard certifications, which you can refer to:

ISO certification: indicates that the supplier has a quality management system to ensure that the production process is controllable.

Automotive AEC-Q101: ensures the reliability of silicon carbide products in the automotive field. This standard is suitable for electric vehicles and other high-demand environments.

Material specification standards: such as ASTM standards or internal company standards to ensure that silicon carbide performance meets expectations.

Cost considerations

Cost price is one of the issues that consumers are most concerned about. As a decision maker, you need to not only pay attention to the initial price of the product, but also consider the following factors:

Initial purchase cost:

Choose the appropriate product grade according to your budget (e.g. high-purity silicon carbide is more expensive, if you only have ordinary applications, you can use medium-purity silicon carbide with a higher cost-effectiveness)

Life cycle:

High-quality silicon carbide will have a longer service life, which can effectively reduce the frequency of your replacement.

Using products with long lifespans reduces your costs to a certain extent.

Maintenance costs:

Silicon carbide may wear to varying degrees after long-term use. If you choose silicon carbide products with good wear resistance, you can significantly reduce maintenance costs.

High-quality silicon carbide products have better stability under high temperature and high pressure conditions, which can reduce unexpected losses.

Summarize

After reading this article, you will have a good understanding of silicon carbide, from its performance to its uses to how to buy it. I hope this comprehensive guide can help you.

FAQs.

1. Which Is Harder: Silicon Carbide or Aluminum Oxide?

Silicon carbide is harder, with a Mohs hardness of 9.5, while aluminum oxide has a Mohs hardness of 9.0. However, silicon carbide is more expensive, and aluminum oxide is the first choice for some grinding applications with low hardness.

Recommended articles for you to learn more: Silicon carbide VS aluminum oxide

2. What Materials Can Silicon Carbide Sandpaper Sand?

Silicon carbide sandpaper is suitable for a wide range of materials:

Hard materials: glass, stone, ceramics, alloys

Non-ferrous metals: aluminum, brass, copper

Modern composite materials: fiberglass, carbon fiber

Finishing between coatings: paint, varnish

3. How Conductive Is Silicon Carbide?

The conductivity of silicon carbide changes with doping and temperature:

Intrinsic conductivity: semi-insulating

N-type doping: 600-800 S/cm

P-type doping: 300-500 S/cm

Temperature coefficient: positive (conductivity increases with increasing temperature)

4. What Is The Melting Point of Silicon Carbide?

Silicon carbide does not melt, but it decomposes:

Decomposition temperature: °C (°F)

Sublimation temperature: °C (°F)

Using limit temperature: °C (°F)

5. What Is The Density of Silicon Carbide Crystal?

Pure SiC: 3.21 g/cm³

Commercial grade: 3.10-3.25 g/cm³

Sintered SiC: 2.98-3.15 g/cm³

Lower density can be preferred for lightweight applications

6. What Are The Common Uses of Silicon Carbide in Daily Life?

Silicon carbide is used in daily life in the following ways:

Kitchen: non-stick cookware coating

Automotive: brake pads and clutch plates

Home maintenance: sandpaper and grinding wheels

Electronics: smartphones and LED lighting

Jewelry: moissanite gemstones

7. What Is The Difference Between Silicon Carbide and Carbide?

The main differences between silicon carbide and other carbides are as follows:

Silicon carbide (SiC): a specific compound of silicon and carbon

Carbide: a general term for any carbon compound containing a less electronegative element

Tungsten carbide, titanium carbide and silicon carbide are all different types of carbides, each of which has unique properties and applications

8. How Much Does Silicon Carbide Cost?

We will provide you with the current market price reference in :

Wafer: $500- per 6-inch wafer

Power device: 3-5 times silicon equivalent

Abrasive grade: $2-5 per pound

High purity powder: $100-300 per kilogram, the price may change according to the quality and quantity you choose

9. What Is The Manufacturing Process For Silicon Carbide Wafers?

The key production steps are as follows:

Crystal growth: modified Lely method or CVD

Wafer cutting: diamond wire saw

Surface treatment: grinding and polishing

Quality control: X-ray analysis and defect inspection. This production cycle usually takes 2-3 weeks.

10. What Are The Advantages of Silicon Carbide Semiconductors?

Compared with traditional semiconductors, the main advantages of silicon carbide are as follows:

Higher operating temperature than traditional semiconductors, up to 400°C

10 times higher breakdown voltage

3 times higher band gap

Lower switching losses

Better thermal conductivity

11. What Are The Applications of Silicon Carbide Fibers?

Silicon carbide fibers can be used in a variety of applications:

Aerospace composites: engine components

Nuclear applications: fuel rod cladding

High temperature filters: industrial processes

Thermal protection: heat shields

Structural reinforcement: advanced ceramics

12. How To Identify The Quality of Silicon Carbide?

The quality indicators of silicon carbide are as follows:

Color: The darker the color of silicon carbide, the higher the impurity content

Crystal structure: single crystal and polycrystalline

Electrical properties: resistivity measurement

Purity level: semiconductor grade is 99.%

Surface defects: visual inspection under a microscope

13. What Is The Thermal Conductivity of Silicon Carbide?

The thermal conductivity of high-purity silicon carbide is 120-270 W/mK.

Over the past decade, the incorporation of Silicon Carbide (SiC) in power, LED, and RF devices has steadily increased, allowing for this technology to progressively mature in all aspects. This is due to the many desirable qualities this wide-bandgap substrate has relative to its silicon (Si)-based counterparts — the ability to achieve much higher power per given die size, at much faster switching speeds, and with excellent thermal performance.

Contrary to popular opinion, all of these characteristics actually lead to the employment of fewer power devices, magnetics, and respective gate drivers, actually yielding a lower system cost when compared with Si-based high-power designs (e.g., OBCs, string inverters). From growing the boules to the fabrication and device packaging, the stringent qualification process for SiC devices has been thoroughly developed. Moreover, with over 30 years of legacy in SiC, Wolfspeed power devices have experienced over 6 trillion field hours — reaching a point at which data on long-term reliability can be adequately ascertained.

This article dives into the qualification process of SiC components and how this yields high extrinsic device reliability while looking into the accumulated data on long-term wear-out for SiC. There is an additional discussion regarding industry capacity and continuity of supply to support the ever-growing demand for SiC-based devices.

Why Silicon Carbide?

The SiC power device has steadily infiltrated a number of industry verticals for power devices from solar power conversion, power grid systems, industrial motor conversion, and on-board charging for EVs. The proliferation of SiC-based MOSFETs and diodes are for a good reason — when compared with standard Si-based power devices (e.g., IGBTs, SJ MOSFETs), SiC devices offer half the losses, at a third of the size, and with 20% lower system costs. The higher power conversion per die size is due to the fact that SiC has nearly 3× the bandgap, 10× the breakdown electric field, over 2× the thermal conductivity, and 5× the power density when compared with Si.

As more and more designers are currently, or have in the past, designed with SiC, several fundamental long-term effectiveness questions based on SiC quality, reliability, and supply crop up. Some frequently asked questions include:

• What qualifications do you apply to SiC?
• How do I know if SiC is reliable?
• What capacity will the SiC market need and will it have enough?
• How do you predict long-term wearout with SiC?

These are critical questions for vendors to ask in order to position themselves strongly within the power device market long term. The Si substrate has a familiarity within the industry from its fabrication to packaging and device-level completion — the technology has been able to mature over 60 years in the fab and the field. However, this does not outweigh SiC in the power device market. Wolfspeed has over 30 years of legacy with SiC, from delivering the world’s first SiC MOSFET in to being the only vertically integrated SiC manufacturer from growing the SiC boules to packaging die — all while steadily driving up voltage and current ratings, increasing wafer diameters to bring down cost per unit, and meeting stringent industry and automotive qualifications. The massive benefit of this focused effort over three decades? The collection of relevant data to perform in-depth reliability analysis comparable with that of Si.

A basic glance at quality and reliability: The bathtub curve

Reliability engineers are familiar with the basic bathtub curve to understand the varying regions of device failures (Figure 1). The first region (Region I) of the bathtub curve includes wear-in failures, or “infant mortality,” and is often dependent on rigorous device qualification. Region II of the bathtub curve relates to the steady state, or field failure rate with constant (random) failures such as external stressors that lead to failures. Finally, Region III of the curve relates to long-term wear-out of the device with accumulation of damage over time. Each of these regions of the bathtub curve correlate to different types of deterioration modeling. In other words, the three areas that the market cares about involve the following:

1. Extrinsic failures in the early life of the device
2. Observed failures during the steady-state field life of the device
3. Intrinsic failures that occur as the device ages

For the power device, the first region relies on qualification testing. The second region relies on device hours (e.g., 1,000 hours, 10,000 hours, 1 million hours) in the field to accumulate sufficient data to acquire a failure in time (FIT) rate. The third region relies on lifetime prediction models and mean time to failure (MTTF) calculations.

Extrinsic reliability: SiC-specific potential failure mechanisms for infant mortality

SiC MOSFETs involve several salient features that, when optimized, offer high quality and more reliability. These include:

• The SiC epitaxial layer (e.g., defects, thickness, doping)
• MOS channel (e.g., inversion-layer mobility, gate dielectric)
• Edge terminations
• Implantation/doping
• Ohmic contacts

The two potential failure modes of a SiC device are related to blocking voltage and gate voltage. Figure 2 shows the common failure mechanisms in SiC devices as well as some industry reliability tests to ensure proper operation of the MOSFET.

Gate oxide breakdown

Gate oxide breakdown can occur in SiC MOSFETs due to the smaller thickness of the gate oxide layer combined with the application of a higher electric field relative to Si-based devices. This can cause the threshold voltage to increase over long periods of time. However, this problem is sidestepped when MOSFET gate voltage is regularly switched between on and off states as the threshold voltage reverses during the switch.

Edge termination breakdown

In planar structures, breakdown voltages at planar junctions can limit the potential reverse-bias blocking capability of SiC MOSFETs due to an electric field crowding effect. With this effect, the electric field becomes spatially non-uniform and causes crowding at the device periphery. Effective edge termination structures can mitigate this effect and increase device reliability. In most devices, the blocking voltage does not reach the ideal breakdown value for one of two reasons: defects in the active area or the electric field crowding effect. There is, however, a balancing act between edge termination length (termination area) and material cost. It is therefore optimal to strike a balance between the two.

Intermetal dielectric leakage/breakdown

The electrical and thermal performance of the interconnect in power devices become more challenging as device dimensions become smaller. The intermetal dielectric (IMD) breakdown relates to the IMD leakage current that occurs in the event of dielectric breakdown due to a high voltage pulse or continuous power. This is typically tested with the time-dependent dielectric breakdown (TDDB) test in order to screen out defect-related breakdowns that can lead to infant mortality.

Steady-state field reliability: Silicon Carbide-specific potential random failure mechanisms

Neutron collisions

More often than not, the random failure mechanism for an already-qualified SiC device would be due to cosmic radiation. Terrestrial neutron irradiation occurs when neutrons collide with lattice atoms in the power device; this causes atoms to recoil and protons and/or neutrons to be emitted. Charges spike along these trajectories, leaving ionization trails that are not negligible — on the order of micrometers, which is comparable with epilayer thickness. The current transients that are induced by the neutron collision can cause failures in both bipolar and MOSFET-type SiC devices. In the bipolar NPN, bipolar turn-on can occur, causing burnout. In the MOSFET, charge accumulation can occur, causing a gate oxide failure.

The SiC device has an intrinsically higher reliability when compared with Si counterparts (e.g., IGBTs) due to the relatively smaller die size — there is far less physical area to get hit with a neutron bomb. As demonstrated by the graph in Figure 3, the failure rates increase proportionally with device area while the failure rates also decrease as voltage rating increases. This is the main failure mechanism at steady-state, particularly for high-altitude applications such as aerospace, high-altitude power installations, or even an EV driving around a mountain.

The first third of the bathtub curve: How are Silicon Carbide devices qualified?

With these common failure mechanisms in mind, Wolfspeed utilizes proven industry-standard testing to ensure the SiC devices are of the utmost quality prior to releasing them (Figure 2). This includes the qualification testing across large samples sizes in different lots to ensure a 90% confidence, or <1% failure rate. The product qualification that the SiC devices undergo ensures a high extrinsic reliability.

Wolfspeed leverages industrial (JEDEC) and automotive standards (AEC-Q101) that were constructed around silicon. The AEC-Q101 standard is generally more stringent than the JEDEC: The automotive standard requires 77 samples to be tested across three separate lots, while the JEDEC industrial standards require 25 samples across three lots. The AEC standards require the high levels of electrical and optical screening available and also monitor drift and shift within the lots under test. The major industry consortia including JEDEC, IEC, AEC, and JEITA are all actively developing SiC-specific standards to meet the needs for SiC technology and customer base. Wolfspeed is integrally involved in this process, working with subcommittees and task groups on SiC reliability and qualification testing.

Typically, a higher failure rate is seen at the extrinsic part of the bathtub curve, as this is the stage where faulty components are screened out. Table 1 lists the typical product qualification that a SiC device undergoes at Wolfspeed. Table 2 lists how these stress tests relate to performance for devices that require a high drain bias, high altitude, high humidity, high gate bias, or third-quadrant operation — each of these requirements relate to specific potential failure mechanisms. A high blocking voltage requires a high electrical field reliability, while a high gate oxide voltage needs a high gate oxide reliability. A high switching speed necessitates a high threshold voltage (VGS(th)) stability, high body diode is requisite for third-quadrant operation, and finally, there is a need for high terrestrial neutron reliability for high-altitude applications.

Table 1

Typical Product Qualification

Stress TestSample Size Per Lot# of LotsReference StandardRequirements/DescriptionAccept on # FailedHigh Temperature Reverse BiasHTRB773MIL-STD-750-1 M Method A hours at Vmax and Tcmax0High Temperature Gate BiasHTGB77 each
Vgs>0 and Vgs<03JESD22 A- hours at Vmax and Vgasmin and Tcmax0Temperature CyclingTC773JESD22 A- cycles Ta_max/Ta_min0Unbiased Highly Accelerated Stress TestUHAST773JESD22 A- hours at 130C and 85% RH0High Humidity High Temperature Reverse BiasH3TRB773JESD22 A- hours at 85C, 85% RH with device reverse biased to 100V0Intermittent Operational LifeIOL773MIL-STD-750 M cycles, 5 minutes on/5 minutes off, devices powered to ensure DTJ≥100C0Destructive Physical AnalysisDPA23AEC-Q101-004 Section 4Random sample of parts that have successfully completed H3TRB and TC0Time-dependent Dielectric BreakdownTDDB---Apply high gate voltage and test time to failure-Negative Bias Temperature InstabilityNBTI---Measure of threshold voltage shift with time-High Temperature StorageHTS--- hours Tstorage_max-Low Temperature StorageLTS--- hours Tstorage_min-Vibration----Sinusouidal sweep at nominal g (e.g., 5 g), # of hours per x, y, z axis-Mechanical Shock----Half sine pulse at high g (e.g., 30g), # of times in the x, y, z direction-

Table 2

Potential Failure Mechanisms and Corresponding Standard Tests

RequirementGate Oxide BreakdownSiC BreakdownBipolar NPNEdge Termination BreakdownThreshold Voltage DriftIncreased resistance and Reduced Current FlowHigh drain biasHTRB, ALT-HTRBHTRB, ALT-HTRBHTRB, ALT-HTRBHTRB, ALT-HTRBHigh altituden-irradiated HTRBn-irradiated HTRBn-irradiated HTRBHigh humidityTHBTHBHigh gate biasTDDB, HTGBNBTI, PBTI3rd quadrantBody diode HTOL

The middle of the bathtub curve: FIT rates

Observed failures

As stated earlier, Wolfspeed’s legacy in SiC has allowed the compilation of massive amounts of data — over 6 trillion field hours. From this data, FIT rate analysis has been performed on various Wolfspeed SiC devices, as shown in Table 3. While qualification is paramount to ensure basic field reliability, the failures that occur post-qualification truly dictate the viability of the supplier and the quality of the technology. The FIT rates are calculated according to industry standards, wherein the first three months of sale are discounted, the actual field hours are ascertained by factoring in when the device is not being used, and the failures due to cosmetic reasons (e.g., part returns) are discounted from the calculation for accuracy.

As seen in the table, the Wolfspeed FIT rates are typically below 5% ppb and decrease with an increase in field device hours. For this reason, the C6D diode appears to have the highest FIT rate, as it is at the tail end of the extrinsic part of the bathtub curve as a relatively new product.

Table 3

Wolfspeed SiC Power Device Field Reliability

TechnologyFielded Device Hours
(billions)FIT Rate
(valid field failures per billion device hours)C3Dxxx060 Diode.05C4Dxxx120 Diode.2C2M MOSFET.3C3M MOSFET512.3

The last third of the bathtub curve: How do I know if Silicon Carbide is reliable?

Blocking voltage and gate voltage long-term wear-out

The reliability testing of SiC devices and the various lifetime prediction models reveal the typical failure mechanism as the device ages. Wolfspeed employs common testing techniques for intrinsic wear-out by pushing the device to way over the maximum voltage rating or current rating for as long as possible and under the worst conditions possible. In Figure 4, a 1,200-V–rated Wolfspeed MOSFET is pushed up to 1,700 V and predicted hours of operation are obtained based upon this stress.

It should be noted that a 1,200-V–rated Si device generally rolls out at about 1,250 V; therefore, SiC devices generally have much more margin on their voltage ratings. Typically, a 1,200-V–rated SiC MOSFET is working on a 700- to 800-V bus — in this case, there are over 300 million hours of theoretical safe operation before the device fails from a failure mechanism due to blocking voltage. The very same process is applied to gate voltage with the TDDB method.

The TDDB method is another method of understanding the MTTF of power devices. This method subjects a population of MOSFETs to a constant bias at accelerated bias conditions as well as elevated temperatures. The failure time statistics are calculated and Weibull distributions are fit to the failure statistics to estimate lifetime. In Figure 4, a device with a gate voltage rating of 15 V is pushed to beyond 35 V and the probability of failure at the rated gate voltage becomes 50 million device hours. For the Gen3 650-V Wolfspeed MOSFETs, the MTTF stands at 70 million hours at 15-V continuous gate bias, showing a nearly identical gate reliability to the 1,200-V and 1,700-V MOSFETs.

Wolfspeed’s reliability bathtub curve calculator

In order to accurately assess all regions of the bathtub curve for their SiC devices, Wolfspeed developed a bathtub curve calculator that uses a mission profile as input. As shown in Figure 5, this profile is based upon field, qualification, and testing parameters such as VG, VD, TJ, altitude, and an hours histogram.

Power and packaging reliability

While much work is done to ensure the successful operation of a bare die SiC, the power and packaging is an unavoidable reliability issue for both Si and SiC alike. Typically, power packaging is the weakest link, especially at higher temperatures where the failures tend to be more intrinsic in nature (e.g., wire bonds and die attach rip off) The industrial power cycling test is the standard way to characterize the wire bond thermomechanical fatigue wear-out mechanism. It has been shown that the reliability performance is comparable between SiC and Si devices and that failures occur due to thermomechanical fatigue for both types of devices regardless of substrate material.

Understanding Silicon Carbide production capacity

Now that it is well established that SiC is both high-quality and high-reliability, with sufficient data to prove so, the question then pivots to the ability to supply these devices. Wolfspeed is fully invested in meeting present and future demand with a billion-dollar investment in the largest state-of-the-art dedicated SiC fabrication facility. This allows for 30× the original capacity of Wolfspeed, meeting the predicted world market growth of a tenfold increase in SiC semiconductors from to . This is a considerable growth in capacity when compared with other market suppliers of this semiconductor, wherein the closest supplier comes in to serve approximately $720 million of the $2.4 billion market estimate — meeting only a fraction of the capacity capability that Wolfspeed has (Figure 6).

Conclusion

SiC semiconductor applications are expanding greatly due to their excellent performance, power capacity, efficiency, die size, and relative cost-effectiveness. With over 30 years to compile past and present data, there is a large swath of information that allows for FIT rate analysis and extrinsic characterization, ensuring that SiC products are of high quality. This momentum is pushing standards committees to develop and evolve SiC-specific industrial standards, allowing for the continued maturity and utilization of SiC technology. Long-term wear-out and reliability analysis is continually being performed to better assess the failure mechanisms of these devices due to aging, and while it is not as established as Si devices that have had over 60 years of legacy, this data is maturing for more accuracy and dependability.

Wolfspeed is a leading vendor in SiC technology as the only vertically integrated SiC manufacturer with a significant investment in ensuring any and all SiC devices are robust prior to launch. This has also allowed for the continual progression of a strong support ecosystem with design software and tools to implement SiC.

With 6 trillion field hours of data to build upon, extended wear-out studies, and FIT rates in the single digits, Wolfspeed is leading the way on quality, long-term reliability, and safe use of SiC devices.

Want more information on High Silica Fiberglass Filter Meshes? Feel free to contact us.