Synthetic Diamonds And Electronic Applications

Interview conducted by G.P. ThomasSep 27 2013

Adrian Wilson, Head of Technologies at Element Six, talks to AZoM about the unique properties of synthetic diamond and how this can be applied in many different industries. 

Could you please provide a brief introduction to Element Six and the key sectors that it works within?

Established in the 1960s, Element Six is a member of the De Beers Group of Companies and is the international market leader in the manufacturing of synthetic diamond supermaterials. Today, Element Six is a $500 million company with production facilities in 10 countries that serve more than 5,000 customers worldwide.

Synthetic diamond’s unique properties enable dramatic step changes in process and end-product performance that are applicable to a wide array of industries including optics, semiconductors, sanitization and water treatment, and sensors.

Element Six specializes in ‘Supermaterials’ – could you explain the concept of a supermaterial and also provide some examples?

Unique engineering materials, such as synthetic diamond, cubic boron nitride, silicon cemented diamond and tungsten carbide, are considered ‘supermaterials’ due to their unrivalled ability to deliver extreme performance across a variety of applications.

For example, synthetic diamond’s molecular structure makes it the world’s most versatile supermaterial—carbon atoms linked together in a dense tetrahedral arrangement make it incredibly strong and give it greater hardness than all other materials.

Synthetic diamond’s unequalled hardness makes it an ideal material for cutters used in oil and gas drilling, where it enables longer tool lifetime by minimizing wear. Its high thermal conductivity makes it an innovative heat spreader for use in electronics, an industry that sees 50 percent of electronic failures occur as a result of heat.

Additionally, a small electrical current passing through synthetic diamond creates Ozone, which is a powerful disinfectant and environmentally friendly alternative to bleach. This is just a few examples of the many transformative applications being explored with synthetic diamond supermaterials.

Element Six’s CVD diamond heat spreaders. Image credit: Element Six

Everybody knows of diamond as a sought-after material for jewellery, but it is also extremely important in the materials science sphere. What key properties does diamond have that make it indispensable in industrial applications?

The exceptional hardness of synthetic diamond has inherent advantages in mechanical and abrasive applications. However, it also has many other extreme properties, including:

• The broadest optical transmission spectrum
• The highest known thermal conductivity
• A wide electronic band gap
• The highest known resistance to thermal shock
• Excellent electric insulator properties
• A very low coefficient of friction
• Chemically and biologically inert

The above properties make synthetic diamond indispensable in a variety of industrial applications. Its high thermal conductivity enables revolutionary advancements in electronics and semiconductor manufacturing. While high-power resistant synthetic diamond optical windows are a key enabler of Laser Produced Plasma (LPP) extreme ultraviolet (EUV) lithography systems.

As an electrode, synthetic diamond can be used in waste water treatment and the production of strong oxidants. In electroanalytical applications, including biomedical sensors, synthetic diamond sensing material provides stable electrochemical properties that enable the highest levels of sensitivity, selectivity and responsiveness.

Synthetic diamond has also recently emerged as a candidate material for a range of quantum-based applications including: secure quantum communication, quantum computing and magnetic/electric field sensing.

Are there any major differences between synthetic and natural diamond?

The molecular structures of natural and synthetic diamond are identical. The primary difference between natural and synthetic diamond is that the latter is produced, by man, in one of two ways—chemical vapor deposition, or high-pressure, high-temperature (HPHT) synthesis.

When synthetic diamond is created using HPHT synthesis, more than 55,000 atmospheres of pressure are delivered—equivalent to stacking approximately 5,000 cars on a jar of peanut butter—at temperatures that would melt steel. When diamond is produced via chemical vapor deposition (CVD), substrates are prepared and various amounts of gases, including a carbon source (methane) and hydrogen, are introduced and ionized into chemically active radicals.

CVD diamond growth enables Element Six to control the chemical impurities and properties introduced during diamond growth over large areas on various substrates, engineering the material with different elements depending on the specific application of choice.

Whereas natural diamonds are highly valuable for their unique nature, Element Six goes through great lengths to tightly control and replicate very specific properties in synthetic diamond material to ensure a reliable and cost-effective engineering material.

Looking at diamond as a heat spreader in electronics, could you explain a little more about the role of diamond in these applications and why this is important with increasingly smaller and more powerful electronic devices?

Most materials with high thermal conductivity are also electrically conductive. In contrast, synthetic diamond has high thermal conductivity, but negligible electrical conductivity. This is invaluable for electronics, where diamond is used as a heat sink. Efficient heat dissipation prolongs the lifetime of those electronic devices without impacting performance.

In semiconductor technology, synthetic diamond heat spreaders prevent silicon and other semiconducting materials from overheating. This is especially important as, in accordance with Moore’s Law, electronic devices become smaller and more powerful and it becomes more and more difficult to manage heat. Synthetic diamond has thus become a critical enabling technology, given its ability to act as a heat sink.

CVD is the method that Element Six uses to produce the synthetic diamond for these applications – could you outline why this process is used and how it influences the final properties of the diamond heat spreader?

At Element Six, we employ a proprietary microwave chemical vapor deposition (CVD) process to grow synthetic diamond. This method allows us to tightly control growth conditions, eliminate chemical impurities and engineer various properties into the diamond material. This ensures production of a highly consistent material with predictable properties and behavior that enables a diverse range of applications, including heat spreaders for high power electronics.

Could you explain in more detail Element Six’s GaN-on-diamond semiconductor technology, and how this is utilized?

Element Six’s GaN-on-diamond semiconductor wafer technology is the first commercially available technology of its kind. Designed for manufacturers of transistor-based circuits with high power, temperature and frequency characteristics, GaN-on-diamond enables rapid, efficient and cost-effective heat extraction. This process reduces the operating temperatures of packaged devices, addressing heat issues that account for more than 50 percent of all electronic failures.

GaN-on-diamond wafers are among the world’s most thermally conductive materials. In fact, GaN on free-standing polycrystalline CVD diamond is up to five times more conductive than copper at room temperature—helping to lower operating temperature and overall system level costs, while increasing the power of RF devices. GaN-on-diamond systems may be implemented within power amplifiers and microwave and millimeter wave circuits to dramatically reduce device temperatures, while maintaining output performance.

What are some of the new quantum-based developments associated with synthetic diamond?

Recently, Element Six, working in collaboration with Delft University of Technology in the Netherlands, successfully achieved quantum entanglement between atom-like defects in two pieces of diamond.

This breakthrough is a major step toward achieving a diamond-based quantum network, quantum repeaters and long-distance teleportation—changing the way information is processed and enabling new systems to efficiently tackle problems inaccessible by today’s information networks and computers.

This quantum entanglement was achieved using synthetic diamond engineered to contain a particular defect that could be manipulated using light and microwaves. The defect consisted of a single nitrogen atom adjacent to a missing carbon atom—known as a nitrogen vacancy (NV) defect.

The light emitted from the NV defect allowed the defect’s quantum properties to be ‘read-out’ using a microscope. By forming small lenses around the NV defect and carefully tuning the light emitted through electric fields, the Delft team was able to make the two NV defects emit indistinguishable particles of light (photons). These photons contained the quantum information of the NV defect and further manipulation allowed the quantum-mechanical entanglement of the two defects

The findings demonstrated our ability to control a single atom-like defect in the diamond lattice at the parts-per-trillion level—an important achievement that will help us not only create a quantum network to process information, but ultimately a future quantum computer.

We have only really scraped the surface of the range of applications for synthetic diamond products – could you please give a brief overview of some further application areas that are important to Element Six?

Some further application areas not mentioned in the previous questions include :

• Using diamond’s inert property and it ability to be boron doped to make it conductive to produce highly reversible electrochemical sensors.
• Using boron doped diamond in a bi-polar electrochemical cell to break down caustic liquids into less harmful chemicals.
• Growing diamond into a dome shape for the use as a speaker tweeter for high end audio systems.
• Using very high purity single crystal diamond with nitrogen-vacancy centers to create very small footprint magnetometers with the ability to sense by magnitude and direction of magnetic fields.

What are some of the typical issues encountered when using synthetic diamond and how does Element Six seek to mitigate these?

For many emerging applications our customers are not familiar with how to integrate synthetic diamond in their product. We mitigate this unfamiliarity by providing application support to our customers which ranges from basic technical advice all the way through to providing metallisation services and even in some instances, diamond integrated sub-systems.

How do you feel the use of synthetic diamond in engineering and electronics will progress over the next decade?

With the ever increasing need for higher power densities in electronic components, the thermal challenge will only be exacerbated. Synthetic diamond will become a requirement for heat management for many Rf and power device types.

For non-abrasive uses, we fully expect an acceleration in the adoption of diamond in semiconductors, optics, sensors and water treatment as diamond’s unique properties demonstrate game changing value for our customers.

We expect the abrasive use of synthetic diamond to continue to grow as more challenging composite materials require machining, consumers demand more aesthetically pleasing machined surfaces and the economics of synthetic diamond as a low wear rate material provide differentiation for its users.

About Adrian Wilson

Adrian Wilson has been with Element Six since July 2011 as Head of Technologies. Adrian joined Element Six from his role as vice president/general Mmnager SoC (System-on-Chip) and head of corporate marketing at California-based FormFactor Inc, a high-tech supplier to global chip manufacturers, where he was responsible for the SoC Business Unit, all corporate marketing activities and strategic planning.

He has over 20 years of experience in marketing, sales and general management, with a particular emphasis in new product and new market developments, and held various roles based in California, Germany and the UK, including president and CEO of a semi-conductor equipment start-up.

Adrian obtained his bachelor’s degree (Honours) in electronics engineering and his postgraduate diploma in marketing at De Montfort University. He holds a master’s degree in technology management which he completed at La Trobe University/APESMA in Melbourne, Australia. Adrian is also a Fellow of the Chartered Institute of Marketing.