everything PE interviewed Denis Marcon from Innoscience who is directly responsible for Innoscience’s GaN business and marketing in Europe and the United States. Innoscience is an integrated device manufacturer fully focused on GaN technology.
Q. Can you give us a brief history of Innoscience? When was the company founded? What was the objective?
Denis Marcon: Innoscience was founded in December 2015 with the aim of creating the world’s largest manufacturing site and Integrated Device Manufacturer (IDM) fully focused on 8-inch GaN-on-Si technology.
Innoscience executives understood from the very beginning that to enable the wide adoption of GaN technology in the market, performance and reliability were just the starting point. They understood that the power electronics industry demanded three additional key aspects. First, GaN must be affordable as the industry is not willing to pay a big premium for it. Second, a large manufacturing capacity is required to absorb large demands and associated fluctuations. Thirdly, users require the security of supply so that they can develop their products and systems using GaN devices without worrying about possible production discontinuation caused by changes in the supply chain.
Taking these conditions into consideration, Innoscience understood that only by focusing and dramatically scaling up the volume of GaN device manufacturing and controlling its production fabs, would it be possible to address the industry’s three requirements (price, volume, and security of supply).
For this reason, from the beginning, Innoscience has strategically focused on 8-inch wafer production, which results in 80% more devices per wafer compared to a 6-inch wafer. Innoscience also decided to develop a silicon-compatible process flow so that all the years of experience and optimization for the mass production of silicon transistors could be leveraged for the production of GaN wafers.
Today, Innoscience has achieved its initial objective. Thanks to the two large 8-inch GaN-on-Si fabs equipped with the latest generation of (silicon) 8-inch production tools, Innoscience is the world’s largest manufacturing site and IDM is fully focused on GaN. Today, the company produces 10,000 wafers per month (wpm) and it will keep expanding its production capacity towards and beyond 70,000 wpm in 2025.
Q. Can you tell us about your 8-inch GaN-on-Si Process Technology?
Denis Marcon: Innoscience is using the latest generation of Aixtron MOCVD reactor G5+C to grow 8-inch GaN-on-Si wafers – while other GaN players are still today on 4-inch or 6-inch wafer sizes. Innoscience GaN-on-Si epitaxial process has been optimized to systematically obtain uniform and reproducible crack-free epi-wafers with low dislocations density and defects both for HV (650 V) and LV (<150 V) devices.
Because Innoscience controls the full manufacturing flow (from epitaxy to final transistor completion), the company has been able to improve every aspect to obtain both high wafer and device yield.
Differently from the typical III-V process, Innoscience is using a Silicon-compatible process flow to manufacture its 8-inch GaN-on-Si power devices. This is leveraging years of learning and optimization done for the mass production of Silicon technology for the production of cost-effective 8-inch GaN-on-Si power transistors. Indeed, Silicon device manufacturers supported by the tool makers, have optimized their process in terms of throughput (wafer-per-hour) and quality to utilize every inch of their Silicon wafer and produce as many wafers as possible with their line.
Q. Can you tell us about your 8-inch GaN-on-Si Device Technology?
Denis Marcon: The power semiconductor market demands a normally-off operation, which means that there is no current conduction when the transistor’s gate is set at 0 V. The natural form of GaN HEMTs (High Electron Mobility Transistors) is normally-on or so-called depletion mode (d-mode), which requires special drivers or to be placed in a cascode package solutions to realize normally-off operation.
Innoscience’s GaN HEMTs are intrinsically normally-off or so-called enhancement mode (e-mode) devices. The normally-off operation is realized by growing a p-GaN layer on top of the AlGaN barrier, deposition, and patterning of a gate metal, and then selectively recessing the p-GaN layer over the AlGaN barrier. The gate metal layer forms a (Schottky) contact with the p-GaN layer, and, as a consequence, the potential in the channel at the equilibrium is lifted-up therefore realizing normally-off/e-mode operation.
On the device technology, it is worth mentioning that we offer both highly performing 30 V-150 V GaN power devices for low and middle voltage range applications as well as high-voltage GaN power devices for 650 V.
Moreover, our device technology features a proprietary strain-enhanced layer, which is a layer deposited after the gate formation. The stress modulation created by the strain enhancement layer induces additional piezoelectric polarizations; this causes the 2DEG density to increase and thus the sheet resistance to decrease by 66% compared with a device without a strain layer. Since the strain enhancement layer is deposited after the gate formation, it only affects the resistance in the access region and it does not impact other device parameters such as threshold, leakage, etc. The immediate benefit of using this technology is to obtain devices with lower specific on-resistance, which means more devices per 8-inch wafer. At the recent ISPSD 2022, we have also demonstrated that such a layer has also a positive effect on the reliability and dynamic Rds(on) performance of the device by suppressing hot-electron injection (and the associated degradation).
In terms of device technology, it is also worth mentioning our bidirectional GaN device (BiGaN) is the first GaN device that can switch in both directions. This is also the first GaN device to enter the mobile phone in the battery management system (BMS). With this technology is possible to replace two back-to-back MOSFETs with one BiGaN HEMT resulting in reducing on-state resistance by 50%, chip size by 70%, and temperature rise by 40%.
Q. Can you tell us about your Epitaxy Services and Capability?
Denis Marcon: Innoscience has developed proprietary 8-inch GaN-on-Si epi-buffer technology optimized for high-voltage (HV) and low-voltage (LV) devices. The epi-process is seamless running on the many Aixtron G5+C installed at Innoscience’s fab. Today, we are equipped for 10,000+ wpm and, as said above, we plan to further expand our capacity.
Q. What are the advantages of GaN-on-Si over the Conventional GaN-on-SiC technology?
Denis Marcon: The main differences are cost and wafer size. Indeed, GaN-on-Si wafers are available on 8-inch wafer sizes and potentially can even scale beyond that towards 12-inch. Instead, GaN-on-SiC wafers are normally available on a small wafer size (4-6-inch wafers) and are much more expensive than GaN-on-Si due to the SiC substrate. Yet, SiC has better thermal conductivity than Silicon, and thus in high-end applications (especially RF) users prefer GaN-on-SiC over GaN-on-Si despite its availability in lower wafer size and being much more expensive too. However, for mass-market applications where there is a trade-off between performance and cost, GaN-on-Si is the preferred choice.
Q. What types of products do you develop? Are all the products developed in your foundry?
Denis Marcon: Yes, all the products are fully designed, and developed in our foundry on our 8-inch GaN-on-Si wafers. As stated above, Innoscience offers a full range of normally-off (e-mode) high and low-voltage GaN HEMTs as shown below:
Q. What are GaN HEMTs? What are their applications and how do they compare to Silicon Based Products?
Denis Marcon: GaN HEMTs (High Electron Mobility Transistors) are field-effect transistors (FETs) that switch faster and more efficiently than silicon power transistors thanks to the inherent property of GaN (i.e. wide bandgap) and the spontaneous formation of a two-dimensional electron gas (2DEG) that is well confirmed at the interface between GaN channel and AlGaN barrier. The key figure of merit (FOM) of power switching transistors is the product of the on-resistance (RDS(ON)), which determines the static dissipation, times the gate charge (QG), which determines the dynamic dissipation, FOM = RDS(ON) x QG. The lower the better.
For a given application voltage, this FOM on GaN HEMT is much lower than on Silicon power transistors. This means that GaN HEMTs can switch faster than Silicon power devices without having an impact on the efficiency of the power conversion. Since the size of passive devices (i.e. capacitors and inductors) scale inversely with the operating frequency (i.e. the higher the frequency, the smaller the passive devices), GaN-based converters are much smaller and more efficient than Silicon-based converters.
In addition, Silicon power transistors suffer from reverse recovery current that has a negative impact on the efficiency due to the high loss associated with the body diode reverse recovery. To avoid this problem, often a dual boost bridgeless PFC configuration is used in Silicon-based AC/DC converters. On the other hand, GaN HEMTs have no body diode and thus the turn-off loss associated with the reverse recovery current is negligible. Thus, thanks to the absence of the body diode in GaN HEMT a simple and more cost-effective architecture can be used such as Totem-pole bridgeless PFC.
Q. What is the difference between HV GaN HEMT and LV GaN HEMT?
Denis Marcon: Innoscience’s HV GaN HEMTs are rated for operation having voltages up to 650 VDS despite the devices being qualified at 80% of such voltage as per JEDEC standards. LV GaN HEMTs operate from 30 V and up to 150 VDS. For any given voltage, Innoscience’s HV and LV GaN HEMTs outperform the Silicon counterpart in terms of RDS(ON) x QG.
Q. What are InnoGaN transistors? How are they different from other transistors available in the market?
Denis Marcon: InnoGaN is Innoscience’s brand name for the company’s GaN HEMTs. They are faster, more efficient, and smaller than silicon-based transistors. Innoscience’s devices are intrinsically normally off (e-mode) which is the industry’s preferred option. Other manufacturers have to include separate drivers when using depletion-mode (d-mode) devices. InnoGaN GaN HEMTs feature low RDS(on).
The first difference of the InnoGaN portfolio is the availability of both LV and HV devices. Indeed, other producers in the market are either focus on LV or HV devices. At Innoscience, thanks to our scale, we produce both by having dedicated teams and processes to manufacture high-performing and reliable LV and HV devices. Thus customers can find Innoscience a one-stop-shop for their needs.
Performance-wise, they are comparable or better than other transistors available in the market e.g. in terms of RDS(ON) x QG. Moreover, InnoGaN features the strain-enhanced layer technology that assures lower dynamic RDS(ON) and excellent reliability as mentioned earlier.
A key difference is that InnoGaN power devices are highly cost-competitive aiming to offer a valid and better alternative to Silicon technology without having a big price gap. This is thanks to the fact that Innoscience is today the only mass-volume producer of 8-inch GaN-on-Si power. That results in 80% more devices per wafer with concerning-inch and thus they are intrinsically cheaper as the yield is comparable or better. Innoscience is also leveraging an economy of scale by producing an 8-inch GaN-on-Si power device on its own two fabs (i.e. whereas other players are fabless and need to work with foundries that still have limited production on the 6-inch wafer).
Q. Can you tell us more about your wafer fabrication sites and design centers?
Denis Marcon: Innoscience is an international company with the HQ located in China and offices in several countries such as Europe (Belgium), the USA (California), and South Korea.
Innoscience has two 8-inch fabs based in China at Zhuhai (4,000 wafers per month) and Suzhou (10,000 wafers per month today and going into 70,000 wafers per month in 2025). Both are fully dedicated to the manufacturing of 8-inch GaN-on-Si technology and are equipped with the latest-generation 8-inch manufacturing tools from the most well-known leaders in the industry (e.g. ASML).
Innoscience has an excellent Quality Management System (QMS) based on the international standards ISO9001 and IATF 16949. Innoscience has extensive in-house wafer-level, packaging-level, and system-level testing capabilities that are used to qualify Innoscience’s devices based on JEDEC standards. Innoscience also performs additional reliability and qualification testing as needed by specific applications or if requested by a customer.
Innoscience has R&D facilities in China and in Europe (Belgium) as well as design center in Korea.
Q. Do you offer foundry services to other companies who might want to use your process technology?
Denis Marcon: At the current status we do not offer foundry services. However, we are happy to discuss possible collaboration with customers and partners motivated to widespread GaN technology.
Q. What is the roadmap for your GaN Process Technology?
Denis Marcon: Today, we have a wide portfolio covering both LV and HV devices. On the portfolio on HV devices, we have typical on-resistance ranging from 600 mΩ down to 60 mΩ in the standard DFN package. We are today extending the portfolio towards lower on-resistances aiming to release products with a typical on-resistance of 40, and down to 20 mΩ for higher power applications.
On the LV devices, also there our portfolio includes already a wide on-resistance offering down to 3.2 mΩ at 100 V. Yet, we will also extend the on-resistance offering of our 30 V, 40 V, 100 V, and 150 V devices as well as the package availability being today mostly WLCSP.
On our bidirectional (BiGaN) devices today we only offer a 4.8 mΩ device. In the future, however, we’ll extend both the on-resistance at 40 V as well as the application voltage toward higher values.
Q. What are the market segments you target? What segment is the largest for you?
Denis Marcon: Innoscience is targeting wide-ranging consumer and industrial market sectors such as quick chargers, data centers, LED, solar, LiDAR, e-bike, buck-boost converters, battery management systems, and many more.
About Denis Marcon
Denis Marcon is the General Manager of Innoscience Europe (a subsidiary of Innoscience), and he is directly responsible for Innoscience’s GaN business and marketing in Europe and the United States. Denis received an M.S. degree from the University of Padova in 2006. In 2011, he received the degree of Doctor in Engineering (Ph. D.) from the Catholic University of Leuven and Imec with a thesis entitled “Reliability study of power gallium nitride-based transistors”. Denis is the leading author or co-author of more than 50 journal papers or international conference contributions. After his Ph.D. graduation, Denis has been leading projects aiming to develop GaN HEMTs for several applications (RF and power switching). Thereafter, he joined the business development team of Imec where he was directly responsible for the partnerships with Imec in the field of GaN power electronics as well as for dedicated development and manufacturing of Si-based devices, MEMS, sensors, and micro-systems.