Diamond ICs may finally debut

Diamond ICs may finally debut

Technology News |
By Julien Happich

Diamond semiconductors have been known to be faster, consume less power, be thinner and lighter weight that silicon, but Akhan Semiconductor is the first vendor with its foot-in-the-door of actually realizing its capabilities.

Akhan Semiconductor has a 200mm wafer fab in Gurnee, Ill. and expects to announce a diamond semiconductor IC in a consumer product at the Consumer Electronics Shows (CES) 2017.

Since before 2000, Argonne National Lab has been experimenting with diamond chemical vapour deposition (CVD), spinning off Advanced Diamond Technologies Inc. who partnered with Innovative Micro Technology to produce diamond microelectromechanical systems (MEMS) and inspiring diamond wafer specialists like SP3 Diamond Technologies (Santa Clara, Calif.) to create the CVD equipment to deposit perfect crystalline diamond.

So far, however, the biggest successes for diamond have been in jewelry, abrasives and other industrial uses of man-made diamonds. Nevertheless, Argonne National Labs continued pursuing the dream of diamond semiconductors by finding a way to make diamond—a natural insulator—into a semiconductor and a conductor laying out the path to all diamond chips.



CEO Adam Kahn explains his vision for diamond semiconductors at his namesake company Akahn Semiconductors. (Source: Akahn)

The biggest problem that kept diamond from being commercialized, until now, has been the ease of making p-type transistors, but the difficulty of making n-types, a problem solved by founder and chief executive officer of Akhan Semiconductor, Adam Kahn, who dubbed his process the Miraj Diamond Platform. With both p- and n-type devices, diamond complementary metal oxide semiconductors (CMOS) are now possible. And Akhan Semiconductor hopes to roll out the world’s first CMOS-compatible diamond semiconductors.

“We recently demonstrated CMOS-compatible diamond semiconductors—with both p-type and n-type devices—by successfully fabricating diamond PIN [abbreviation for a p-type—intrinsic, undoped—n-type junction] diodes with a million-times better performance than silicon and one-thousand-times thinner,” Khan told EE Times in an exclusive interview.

Its secret was co-implanting phosphorous in p-type devices and co-doping borium and lithium into n-type devices, resulting in tuneable electronics that achieve comparable performance in both types, thus enabling diamond CMOS. The company’s first demonstrated device, however, was a diamond PIN diode that was a record-breaking 500 nanometers thin. This type of performance is due to diamond being a super wide band-gap material—wider than even silicon carbide and gallium nitride.

Fig. 1: Samples of diamond on silicon from Akhan Semiconductor. (Source: EE Times)

“Thermal analysis showed that there were no hot spots on our PIN either, so there were no parasitic losses like with silicon PIN diodes,” Khan told EE Times.

Khan has also demonstrated 100-GigaHertz (GHz) devices by virtue of the ultra-low resistance of diamond, which can be deposited on silicon, glass, sapphire or metal substrates. Those kind of speeds could revitalize the processor races, which have been idled at 5-Ghz for a decade. Remember when every new processor was clocked at a higher rate. With silicon, 5-GHz is the limit, since their high power consumption and thermal hot-spots turn devices into soup, but diamond has 22-times the thermal conductivity of silicon and five-times that of copper, Kahn claims.

The company’s ultimate goal is to revitalize the processor race with faster and faster clock rates, but for now they are concentrating on power electronics for industry, tuneable optical military applications for countermeasures, and optical mobile consumer applications using diamond as the insulator and semiconductor, but still requiring indium tin oxide (ITO) for contacts (for now).

After banking some successful applications for angel investors and private equity firms who have provided Akahn’s research and development capital so far (to the tune of about $2.5 million). Akahn plans to announce Series A funding later this year, prompting them to come out of the closet at this time to attract a little attention about the possibilities that diamond semiconductors hold.

“We are not developing our mobile and consumer platform yet. For now our major application is power electronics that is more heat efficiency, but which works just like silicon devices—using the same lithograph, etching and metallization steps—just adding the diamond deposition step,” Kahn told us.

But its ultimate goal is to take-the-heat-off (literally) of Big Data applications with ultra-cool-running processors. In fact, the high speeds capable of diamond CMOS is traded off against heat. In other words, data centres could cut their heat vastly, by running diamond processor at the same 5-GHz of silicon, or could bump up their speed to the sub-terahertz range while consuming the same power as silicon.

“Heat is our major issue—half of big data energy today is wasted just keeping its silicon processors cool,” Kahn told us. “Diamond is the next obvious step because it is much more energy efficient. It can also be deposited on glass and sapphire to make completely transparent electronics—for consumer applications, such as transparent mobile devices.”

Moore’s Law will also be extended—yet again—according to Kahn, since the 100-GHz demonstration chips it is showing now use design rules in the 100s of nanometres. That leaves almost a dozen generations of shrinkage before diamond faces the single-atom levels the silicon is facing circus 2025.

Fig. 2: Sample of diamond on silicon from Akhan Semiconductor, May 3, 2016. (Source: EE Times)

“Today we are focusing on power applications on 12-inch wafers, hoping to drive down the costs of production with higher volumes,” Kahn told us. “Our power devices are moving into pilot production at our own fab, but we are using the fab-lite model—that is produce small- to medium-sized runs ourselves, then transferring our process to foundries when we ramp up into volume production.”

Besides power devices, Akahn also claims to have fledgling customers for diamond MEMS devices—specifically for capacitive switching arrays used to dynamically tune antenna in high-end smartphones.

Fig. 3: Sample board with diamond heat sinks (a chip can sit directly on top of a heat sink). Adam Khan, CEO of Akhan Semiconductor, showed the sample to EE Times on May 3, 2016. (Source: EE Times)

Next, besides mobile and data-center processors, Akahn aims to enter the quantum computer field, but not using the nitrogen vacancy method, but rather using their own proprietary doping techniques they are keeping as a trade secret for now.

About the author:

R. Colin Johnson is Advanced Technology Editor at EE Times


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