Executive Interview: Samuel Cho, Cofounder and CTO of RFHIC
What motivated you to start RFHIC in 1999? What was your vision for the company?
RFHIC Corporation, which stands for Radio Frequency Hybrid Integrated Circuit, was founded in 1999 with our cofounder and CEO, David Cho. The motivation all started with an incurable need for cost-effective GaAs components for satellite applications within South Korea. After developing mainly GaAs components, we dove in to developing and manufacturing GaN for telco applications, due to its exceptional performance features.
Our vision for the company is the same as 20 years ago, which is to provide our customers with excellent quality and cost-effective RF and microwave components worldwide.
Discuss the evolution of your products, from the initial focus on the telecom market to high-power amplifiers using GaN technology.
Our initial focus mainly targeted the commercial telecommunications market, especially base stations. After successfully commercializing our GaN on SiC for telco, we expanded towards the defense sector, targeting high-powered radar systems utilizing our high-powered GaN SSPAs. After multiple successful defense and commercial radar projects, we established name value overseas with top global defense contractors, like Raytheon, Lockheed Martin, Northrop Grumman, L3Harris and so much more.
We now have expanded our product portfolio in designing and manufacturing high-powered subsystems for various high-powered industrial, scientific and medical (ISM) applications. With this capability, we can provide our customers with a customizable, one-stop GaN solution — from transistor to system level — lowering costs and getting our customers’ products to market faster.
Describe your technology and manufacturing capabilities for semiconductors, assembly and test. How do these differentiate RFHIC?
RFHIC Corporation is the first and only GaN device to subsystems solution provider in the world, providing our customers with customizable, cost-effective and fast GaN solutions for telco, defense and ISM applications.
Our headquarters facility, located in Anyang, South Korea, is equipped with a grade 4 clean room production facility that is capable of supporting die attach, wire bonding, packaging, chip-on-board, SMT, RF testing, power amplifier assembly, subsystem assembly and ISO-certified quality testing.
I think our biggest differentiator from other suppliers is that we are a fabless company. Being fabless allows us to experiment and utilize different technologies and materials best suited for our customers. It also allows us to allocate our resources more towards R&D, sales and marketing, enabling us to reach a wider audience.
You were an early advocate of GaN. What led you to believe in the technology?
We were able to experiment with various materials like GaAs, LDMOS, GaN on Si and GaN on SC from the beginning, allowing us to get a clear understanding of what compound semiconductor material was the best fit for us to maintain competitiveness. As technology rapidly progressed, we foresaw at an early stage that conventional materials like GaAs and LDMOS would not be capable of efficiently performing at those higher power and frequency levels.
Being the underdogs within the RF/microwave industry, we tend always to look 10, 20 steps ahead of technology to differentiate ourselves from our competitors. We felt GaN on SC was the future. GaN is a wide-bandgap semiconductor material that can sustain high breakdown fields and high saturation velocity compared to other conventional semiconductor materials like silicon or GaAs. SC exhibits exceptional thermal characteristics, allowing the heat to be dissipated in a faster and efficient manner in a much smaller form factor.
In 2017, you purchased the GaN on diamond IP from E6 and announced a GaN on diamond transistor at the 2019 IMS in Boston. Discuss your process for forming the GaN epi on diamond and the maturity of GaN on diamond.
We have reached a stage where GaN is the new “it” compound material and is becoming more widely used among the RF/microwave industry. But I also see within three to four years, GaN on SC running into physical limitations for higher power applications within the defense and ISM industry, which is what led us to developing the GaN on diamond transistor.
Diamond has five times the thermal conductivity of SiC, allowing GaN devices to operate at much higher power levels while maintaining stable temperatures, significantly improving reliability and performance.
RFHIC’s GaN on diamond epi process starts by taking a GaN epitaxial wafer and attaching a temp carrier on top to protect the GaN surface. Once the temp carrier is attached, the substrate and buffer layer will be removed using various etching processes. Once the substrate is removed completely, diamond seed layers are applied. Utilizing a chemical vapor deposition process, polycrystalline diamond is grown on the backside of the epitaxial wafer. Once the diamond is directly deposited, the backside of the diamond substrate goes through a polishing process to enhance the mechanical properties of the epitaxial wafer. Finally, the temp carrier is removed to create a GaN on diamond epitaxial wafer ready for foundry processing.
We have successfully been able to produce samples for our customers and are currently in the process of fine tuning our technology, which we expect to have within the next couple of years.
How do you compare the performance of your GaN on SiC products with those offered by other suppliers?
Although we purchase our GaN on SiC wafers from a foundry source, we perform all packaging measures in house. Back in 2017, we acquired Metallife, a Korean company that specializes in hermetic packages for RF/microwave applications. Through this acquisition, we were able to significantly lower our material costs while providing our customers with high quality products.
We also spearhead our foundry partners to optimize their solutions for our specific customers’ needs, such as higher power, gain and efficiency in the 5G spectrum and other applications.
Unlike your GaN transistor competitors, you have moved up the food chain to develop kilowatt transmitters for radar and industrial applications. Has this been a successful strategy?
Comparative to our large conglomerate competitors, we are still considered an SME (small- and medium-sized enterprise). To maintain competitiveness, we believe it is in our best interest to expand our product portfolio further towards high-powered subsystems to target next-generation radar and ISM applications.
Gaining early traction in major markets is crucial for radar and ISM equipment makers, since they tend to keep their relations with existing suppliers once they have integrated a new system. I believe by being the first company in the world to provide GaN device to multi-kW subsystems gives us a significant first-mover advantage, allowing us to establish a dominant position within the high-powered RF/microwave industry, as well as the flexibility in creating the standards for this industry.
I also think our customers welcome our efforts providing higher integration solutions, as this adds more value and helps our customers focus more on the bigger picture, getting their end products to market faster for their end customers.
What are the leading markets and geographies you currently serve?
We focus on three key industries: wireless infrastructure for telecommunications, power amplifiers and high-power subsystems for military/commercial radars and ISM applications. Currently, our telecom business captures a substantial portion of our revenue, but we do foresee our defense and RF energy business expanding significantly within the next couple of years.
We have a very global and diverse customer portfolio, spread across North America, Europe and Asia.
What markets and applications are driving growth? Do you plan to address mmWave applications?
5G is the key market and application driving our growth. In addition, many radar applications for military and commercial gained momentum in recent years, where much of our R&D work has translated into mass production.
We see significant increases in growth especially within RF energy, due to the wide transition of tube-based systems over to solid-state technology for various high-powered applications.
We believe the mmWave market is considered a very niche market and will be for some time. I think the action is going to be in that sub-6 GHz range for the initial 5G market. With that said, this does not mean we do not plan to serve mmWave applications. If we start to see a wider adoption on the infrastructure side for mmWave, we are certainly poised to support that in the future.
What has been the most satisfying moment during your time at RFHIC?
Recently, I was able to witness a commercial satellite fly off into space, utilizing RFHIC’s GaN components. This moment truly epitomized the ever-expanding roles of GaN technology and the promising future it holds in creating a more connected and better world.