GaN
Using diamond films to enhance thermal performance in electronics packaging
IEEE Electronics Packaging Chapter, Santa Clara Valley Chapter, USA, recently organized a seminar on using diamond films to enhance thermal performance in electronics packaging.
Artificial diamond films are deposited from a mixture of methane and hydrogen — and the deposition of the material is not an expensive process. However, the integration of diamond films and electronic devices requires the development and optimization of new processing lines, which is a costly procedure. LEDs, for instance, have become low-cost components.
Dr. Joana Catarina Mendes, Researcher at the Instituto de Telecomunicações in Portugal said a diamond is metastable allotrope of carbon, where carbon atoms are arranged in a variation of the face‐centered cubic crystal structure known as diamond lattice. It has small atomic radius, extremely strong covalent bonding between sp3 hybrid orbitals, and set of extreme properties. Some properties include high hardness, high demand inertness, high young modules, high thermal conductivity, high bandgap/breakdown field, high electron mobility, and low dielectric constant.
Natural diamond forms 150-200 km inside the earth’s mantle under extreme conditions. Despite their high commercial value in jewelry, natural diamond crystals have too many defects, and cannot be used for electronic applications. Their use is typically limited to tri-bological apps.
Diamond synthesis
Artificial diamond can be formed under high pressure and high temperature (HPHT). The HPHT method reproduces diamond formation conditions inside the earth’s mantle. Diamond seeds are placed at the bottom of a press at 5 GPa. The internal part of the press is heated above 1400°C, and melts the solvent metal. The molten metal dissolves and drags atoms from high purity carbon source, which precipitate on the diamond seed.
Another method is chemical vapor deposition (CVD). CH4 and H2 are typical input gases. The input gases are dissociated and activated. The activated radicals flow and react with C atoms on a substrate. Atomic H etches away non‐sp3 C bonds. Due to their short wavelength (12 cm at 2.45 GHz) the MW power can be supplied as TEM or TM waves. Conductive plasma replaces the outer conductor of coaxial line in plasma discharge region.
Single crystal diamond (SCD) substrate leads to homoepitaxial diamond films. They have the highest thermal conductivity. They are ideal for electronic devices and thermal management apps. Non‐diamond substrate leads to heteroepitaxial/polycrystalline diamond films (PCD). Here, different substrates are possible, such as Si, SiC, GaN, etc.
Diamond films enhance thermal performance in electronics packaging
We can use diamond films to enhance thermal performance in electronics packaging. We can start by integrating diamond and GaN high-electron-mobility transistors (HEMTs). In some cases, the amount of heat generated per unit volume is comparable in magnitude to that encountered at nuclear reactors and at the surface of the sun! We need to cool down the hotspot. We can also grow diamond on the back of GaN wafer.
Next, we have capping diamond, where, films are deposited at 700°C. Metal heat spreaders transfer the heat to the underlying HEMT holder. Thermal resistance is reduced by ≈ 40 percent, and junction temperature is lowered by 100°C @ 25 W/mm. 4’’ GaN‐on‐diamond wafer volume manufacturing was achieved in 2021. Radios and power amplifier modules are available for satellite apps.
Diamond substrate needs GaN/diamond wafer bonding. We can do thermocompression using adhesive layer, as well. We can also do surface-activated bonding (SAB). Another method is Van der Waals (VdW) bonding. The process was initially employed for GaAs thin films.
Other uses
Diamond can be used as chip‐carrier of power LEDs. We can also have diamond carriers for high power LED dice. Diamond can also be used as power board. Depending on the activation energy of the aging processes, LEDs mounted on diamond board will age 60-90 percent slower @350 mA and 90-99 percent @700 mA.
Conclusion
Diamond has been successfully used to improve the thermal management of different devices.
For GaN HEMTs, we have diamond‐capping of passivated HEMTs, direct growth of diamond on back of GaN wafers, bonding of GaN wafers/HEMTs and diamond substrates, commercial GaN‐on‐diamond‐based RF power amplifiers are available for satellite communications. Companies such as Mitsubishi Electric Corp. and Fujitsu are involved in research.
Diamond as chip‐carrier has similar impact of PCD and SCD carriers on LED characteristics. It improves stability of the wavelength with the current, and increases LED lifetime significantly. Diamond as power board increases LED lifetime considerably, when compared to standard MCPCBs. The results can be extrapolated to other devices.
Compound semiconductor epitaxy core of next-gen connectivity
Compound semiconductor epitaxy at the core of next-gen connectivity was presented by Dr. Rodney Pelzel, CTO, iQE at the ITF Beyond 5G at Semicon Europa 2022, Germany.
Epitaxy is the lithography of compound semiconductors. Epitaxy leads to atomic level control, which unlocks the full potential of compound semiconductors. Innovation starts at the materials level. We have upto 400 layers at atomic level. iQE has technology partnerships across the ecosystem, with fabless, foundries, equipment vendors, design services, substrate providers, device makers, and raw materials providers.
iQE has an industry-leading technology portfolio. Scaled materials platform include advanced silicon (AdSi), gallium arsenide (GaAs), gallium nitride (GaN), indium phosphide (InP), gallium antimonide (GaSb), etc. It has scale across all epitaxy manufacturing technologies, such as CVD, MBE, and MOCVD. Materials platforms unlock diversification.
iQE is enabling 5G, big data and beyond. Current epiwafer products include PAs handsets FEM, such as InGaP HBTs/BiHEMTs and GaAs-based PHEMTs, LNAs for handsets FEM, such as GaAs-based PHEMTs, PAs for base stations, such as GaN HEMTs on SiC and Si, transceiver for backhaul and data centre, such as > 25G DFB and PIN/APD. Next-generation epiwafer products include handset FEM with improved InGaP HBTs/BiHEMTs and GaN/Si, improved infrastructure PAs (GaN/Si), and infrastructure and backhaul — higher speed (> 100G DFB and APD).
GaN capability
iQN is leveraging the versatility of GaN. It underpins today’s business and creates waves of innovation for growth. Connect GaN device is expected to grow at 14 percent CAGR from $724 million in 2022 to $1.4 billion in 2027. Power GaN device is projected to grow 50 percent CAGR from $182 million in 2022 to $1.4 billion in 2027. Display GaN devices are likely to grow by 158 percent CAGR from $7.3 million in 2022 to $834 million by 2027, as per Yole Intelligence.
Also, different markets require different substrates. All GaN is not created equally. Different markets require different material solutions. Geopolitical prudence requires local capability for each materials solution. iQE has demonstrated capability across all substrate types for multiple markets. We have global footprint with production and R&D capability in the US and UK.
GaN for RF includes SiC and Si substrates. iQE was first to scale from 4” to 6” SiC substrates, and 8” SiC is now becoming available. It is participant in numerous projects targeting leading-edge GaN performance. It is also a leader in production on 8” Si. iQE is leveraging pedigree in RF to enable GaN solutions for PE and µLED growth markets.
iQE is also looking at Next gen HEMTs, specifically, InAlN. InAl(Ga)N is used for thin barriers and low Rsh. InAIN is also looking at E-mode/D-mode integration. iQE also has GaN for mobile devices. Next-gen connectivity requires innovation at the fundamental materials level. Epitaxy unlocks the full potential of compound semiconductors. GaN is a promising platform for next-gen handsets.
Opportunities for innovation in integrated device technologies
Opportunities for innovation in integrated device technologies was presented by Dr. Gregory U’Ren, Director RF Technologies, XFAB, at the ITF Beyond 5G at Semicon Europa 2022, Germany.
There is solutioning thirst for more data. We have identified pathways to increasing data rates. There can be higher order modulation schemes and significantly larger bandwidth. Technology challenge is the SNR requirement. We must improve receiver sensitivity, and must improve the transmit power and efficiency.
There are challenges and opportunities. There is need for better performance. This can be for the individual components – linearity, noise, gain, and functional integration – cost, convenience, performance. We also need for scale and cost. Short ranges will require network densification. Densification will require higher quantities and likely exacerbated with mMIMO. We also need to have acceptable supply risks for deployment.
RF/mmW technology landscape is showing decreasing functional integration, and increasing and compelling RF figures of merit. Incumbent 4G technologies have weaknesses for mmW. There is growing interest in alternatives such as SiGe and GaN. III-V’s have attractive noise figures and linearity with similar Pdc as RFSOI and SiGe. GaN is similarly attractive with higher CP1, but at the expense of Pdc (~10x). Comparing RF-CMOS, SiGe, and InP, mmW-capable technologies exist. Key differentiation is availability, scale, integration, and cost.
SiGe BiCMOS is integrated within CMOS (500nm – 45nm). It is with foundry and IDM players. It has steady performance evolution and migration to 300mm platforms. There is good functional integration and backend compatibility. Showcase has been SiGe HBT. It is bandgap engineered device with good noise performance for low and high frequency. It allows larger breakdown and reliable operation for PAs.
SiGe BiCMOS provides an opportunity. RF-SOI is the dominant technology for RF switching. State-of-the-art RonCoff figure of merits is < 100 fs. SiGe BiCMOS switch performance is >300 fs. Minimizing RF switching losses is a benefit to the entire RF sub-system.
There is MEMS monolithic integration with HV-CMOS, especially in 8” manufacturing and wafer level process encapsulation. It has electrostatically-actuated membrane. However, it has limited success in RF mobile. RF-MEMS remains relevant. There is an opportunity to achieve functional integration, size, and cost. The challenge is to compete in a narrower field where it can win.
If we look at RF-GaN and InP, they have compelling RF performance, but many formidable challenges to overcome to achieve scale and cost expectations. Only applications that can bear the cost and have no viable alternatives use these technologies.
Role of XFAB
XFAB has been a pioneer with 8” GaN/Si manufactured in a shared CMOS fab environment. It has 5+ year track record with ramp starting 2017. RF GaN is different, but proof of concept is done with power GaN. RF-GaN has a wafer level heterogeneous integration approach. Wafer level integration of III-Vs is also done. There is efficient area utilization of a high value source material. Coupon contains one or more components. Target use case is sparsely populated III-Vs within Si die. Sparse utilization dilutes III-V wafer cost, and significantly expands scale with more efficient material use.
XFAB has ambitions for 5G/6G. XFAB is a specialty foundry with a diverse set of technologies. Power technologies include GaN, SiC, and highly integrated Si solutions with high temperature NVM. Medical solutions combine MEMS and analogue/mixed signal CMOS technologies. It also has mobile and communications including RF-SoI.
RF development roadmap is focused on RFFE. It includes continuous improvement with RF-SoI (XR013), SiGe BiCMOS (XB012) and IHP collaborations, RF GaN heterogenous integration, and exploration of InP with partners. Accommodating SNR constraints is the key driver for next-generation integrated device technologies. Industrial and commercial expectations must also be satisfied to realize a successful deployment.
Advanced engineered substrates for RF apps: from silicon to compound materials
Christophe Maleville, Senior VP of Soitec, presented on advanced Engineered substrates for RF applications: from silicon to compound materials at the recently held ITF Beyond 5G at Semicon Europa 2022, Munich, Germany.
There are many applications of engineered substrates. They can be found in wireless, edge computing, infrastructure, photonics, IoT, sensing, etc. We also need to look at engineered substrates for RF front‐end (RFFE) applications. You can have best active layer on functional substrate. Engineered substrates offer best-in-class solution for performance, energy efficiency, integration and cost benefits. Here, Soitec’s revolutionary Smart Cut is a mature technology.
Substrates for RFFE provide linearity and performance. Here, cost, capacity, integration and thermal aspects are also dimensions considered. We now need to be getting more G from the engineered substrate.
If we look at RF-SoI for RFFE, RFeSi substrates provide benefit of Si CMOS and high-resistivity substrate. There is parasitic reduction and high-speed transistors. High-quality RF passives with improved quality factor and low-loss interconnections are also available. We have highly linear substrate (for RF switches and passives) also at mmW. These are compatible with <40nm nodes. The 45nm RF-SoI solution for 28 GHz fixed-wireless and phase array beamformer is in production (ADI, Mixcom, Anokiwave). Transmitter at >100 GHz was recently presented.
If we look at RF-SoI solution for 28GHz phase-array beam formers FE, RF-SoI provides high-level of digital/analog integration. This is required for bias/gain/phase control, and available memory blocks for large beam tables storing. High-output power (>20 dBm) and gain (>30 dB), as well as breakdown voltage, is available. There are fast and highly linear RF switches (best-in-class). We have technology of choice for fixed-wireless CPEs and mobile infrastructure in urban environments.
RF-SOI is also for > 100 GHz applications. We are beamforming phase-array transmitter at 140 GHz using 45nm RF-SoI CMOS. There is 8-element 140 GHz phased-array transmitter w/ 32dBm Peak EIRP and >16 Gbps 16QAM and 64QAM operation.
FD-SoI is also used for mmW and 6G. FD-SoI gives superior power/performance tradeoff. There is smaller process variability and better analog/RF performance. We can get cost effective: planar CMOS technology, and technology of choice for mmW FEM integration. FD-SoI is already being used for 5G mmW FEM in Google Pixel and Mediatek 5G products. There is an opportunity with 12nm FD-SoI for lower consumption and higher performance.
HR FD-SoI enables improved RF performance. There is 50 percent inductor Q-factor improvement and increased effective resistivity. There is same logic performance as standard FD-SoI. Moving to HR base impacts neither wafer processing nor logic devices performance.
GaN RF technology is typically deployed in the sub 6GHz and X-band. Typical application is in infrastructure (base stations). GaN RF technology for mmW involves gate length scaling for lower-power density and PAE, barrier technology and epitaxy engineering, proved PA operation at 90 GHz (PAE 29 percent), and towards 300mm wafer size for Si compatibility.
New substrate innovation
New substrate innovation is the path to co-integration. GaN on RF-SoI involves replacing HR-Si substrate by RF-SoI. There is better vertical isolation and increased linearity, and higher bandwidth due to smaller feedback (vertical) capacitance. It can allow PA, LNA and switch integration on GaN. There is possible path for Si CMOS co-integration and mobile handset application. Thermal performance is considered in substrate design. InP has major advantages for RF. However, bulk InP has also major drawbacks.
We are looking at piezo-on insulator (PoI) for 5G and beyond. PoI is adopted by key players for single integration and single multiplexer. PoI development is ongoing in low band <1GHz, ultra high band >3.5GHz, and 200mm diameter. Innovative substrates are required for covering extended spectrum beyond 10GHz. These include FR3 deployment and Ku bands (5G NTN).
6G likely-timeline for engineered substrates include R19 or 6G requested in 2024, R20 or 6G study in 2025-26, R21 or 6G phase 1 in 2027, R22 or 6G phase 2 in 2028-29, and finally, 6G evolution or R23 by 2030.
Engineered substrates (for 5G) are being continuously improved for 6G. It is time to identify ‘materials for 6G’ and integrate them into optimized engineer substrate. CMOS and III-V co-integration schemes shall be considered when designing and choosing engineering substrates for 6G. Time is of the essence. Engineered substrates are at the beginning of the value chain, and require collaboration, investment and strong motivation to happen.
New materials required to solve technology challenges, support growth of electronics
Simon T. Dann, President, IQE Taiwan Corp., presented on how compound semiconductors were becoming the next generation of semiconductors, at the ongoing SEMICON Taiwan 2022 Power & Opto Semiconductor Forum.
The future is compound semiconductors. Silicon’s physical limitations are being reached. New materials are required to solve technology challenges. Key megatrends include 5G and connectivity, Industry 4.0, EVs, healthcare, etc. We are also having intelligent connected devices, intelligent transportation, AI on the edge, and metaverse.
Materials are needed to support the growth of electronics. We are scaling to 200mm and 300mm to align to global silicon standards. World’s first 200mm VCSEL is also there. Megatrends enabled by GaN include connect, with excellent RF properties, etc. Power and display are some others. GaN is used for RF and PE markets. We have GaN for display markets. InGaN can achieve RGB with proper strain management. Substrate selection is critical here, and GaN is a native substrate.
All GaN is not created equally. Different markets require different material solutions. IQE is a multi-market, proven global GaN supplier. GaN for RF is the foundation for GaN platform. There are products on SiC and Si substrates. 8″ SiC is now becoming available. IQE is a leader in 8″ SiC. GaN for mobile devices are possibly enabled by InAI(Ga)N. MBE regrowth of contacts are needed to reduce Rc, or get Rc reduction of 3x. There is GaN for power electronics (PE), where high breakdown voltage leads to smaller device size.
GaN/Si buffer engineering is used to reduce high temperature leakage with engineering back barrier. uLEDs are also enabled by GaN. IQE has a strategic partnership with Porotech. Unique technology achieves RGB with GaN.
The future of GaN involves large markets that will motivate global investment. Complex technologies will be mated at the atomic level. Entrance of new platers will drive scaling and integration. We are leveraging our GaN RF expertise to penetrate new markets (PE and uLED).
Evolving lifestyle
Compound semiconductor evolve the lifestyle from RF to lightwave, was presented by Dr. Chuck Huang, Senior AVP, Marketing Center, WIN Semiconductors. There will be multi-level communication in the future. Compound semiconductor is the best choice for wireless.
He introduced lightwave. There are 3D ranging technologies. These include structured light (SL), dToF or pulsed, iToF-AMCW or amplitude-modulated continuous-wave, and iToF-FMCW. This is time of flight-frequency-modulated continuous-wave. For driving safety and unmanned vehicle, there is LiDAR. Moving forward, compound semiconductors is adopted for driving safely. Also, VCSEL provides better resolution and lower latency.
Future life will include 6G and smart sensors. Apps include holographic meetings, teleoperation, autonomous vehicle, and true smart city. Compound semiconductors will be used for 6G/IoT, aero communications, autonomous AR/VR, sensing everything.
III V and optics in data center network hardware
Ms. Claire Szu Ma, Manager of Network Sourcing, CSCP Department, Microsoft, presented on III V and optics in data center network hardware. There are three major sourcing categories. These are: data path and custom silicon, switches, and connectivity. We have the regional network gateway. Inside data center, TOR and MOR are referred to as T0 and T1, along with T2. Hardware is mix of fixed and modular form factor. Connectivity includes copper cables, active cables, and optical transceivers.
Methods to scale to switch and optics are there. Optical module has a relationship with semiconductors. The DSP is using 5nm, 7nm, and 12nm node is enabled. For modular, we are using mature technology mode.
There is some slowdown to VCSEL development. 100G VCSEL will come online in 2023. 50G VCSEL had come in 2019. There are many VCSEL companies, with very few representations from Taiwan. Taiwan should work on VCSEL supply chain.
Light source technology will continue to play an important role in the future. We had a light source upgrade, and introduced CMOS-based DSP as key components. Silicon photonics plays a more important role. There is the Consortium for On-Board Optics (COBO), where Microsoft is a member.
Challenges and opportunities for GaN and compound semiconductors
At the ongoing SEMICON Taiwan 2022 Power & Opto Semiconductor Forum | NExT Forum, the next challenges and opportunity to power GaN and RF GaN technologies, was presented by Dr. Hsien-Chin Chiu, Senior Director, United Microelectronics Corp.
5G and green technologies bring niche opportunities for WBG semiconductors. GaN technology in Taiwan moved back in LED, but moved forward in power and RF electronics. We have a complete ecosystem in Taiwan making GaN great. Compound semiconductor ecosystem is great, and makes your life smarter and colorful.
We are seeing remarkable ramp-up of power GaN. In 2022, power GaN bare die for PD prices were recessed to less than $1. 61-65W of peak power accounted for 65 percent as mainstream, and 100W or more accounted for 18 percent. Power GaN controller/driver solution/players also increased. GaN solutions will reach 52 percent penetration rate in the fast charge market in 2025.
Wafer demand modeling shows MV spec could take around 30 percent of overall power GaN market. Foundry/IDM capacity ratio is 7:3 in 2021. Capacity can be a challenge in 2025. GaN for automotive/data center power supplier market will mature in 2024.
Opportunities in power delivery include 2A1C and 2A2C 65W adopters that were demonstrated. Multi-port output can be simultaneously charge multiple devices. In challenges, GaN power cell high current ability has traded-off with the chip size. For over 65W, PFC app leads to device reliability demand from hard switching. There is harding switching dynamic behavior (SOA) as well.
There are opportunities in mobility and automotive apps. E-bikes and e-scooters can be the first wave app. On-board charger system focus on form factor and efficiency (HV monolithic GaN IC or heterogenous integration). Now, there are over 1200 GaN HEMT technologies.
Datacom and telecom apps also provide opportunities. We are converting AC/DC converter into rack for data centers. We are making 5G micro/macro cells that need efficient and reliable power supply. Form factor and efficiency are always the top priority. GaN specific controller/driver are need with low package-related parasitic.
Heterogenous network in the future also involves 5G — macro, mMIMO, mmWave, and also WiFi-6/7. There will be the co-existence of three layers of wireless networks. It may be possible for GaN inside 5G smartphones. Battery voltage can increase to 4.5V or 5V. E-mode RG GaN will be needed for high PAE. We will need PA+LNA and software MMICs solution.
There will be 5G impact on RF front-ends for telecom infrastructure. Also, base station market starts ramping up in the coming three years. 5G ratio will exceed 50 percent in 2024, and reach 68 percent by 2025. We also have RF GaN in military, especially, defense radar. We can have the beam steering radar. We can develop next-generation military radar, as well as space system and communication service. We also have opportunities in rare earth nitride/GaN HEMT, mmW GaN on SiC, DUV stepper for fine-line gate, heterogenous integration in mmW apps. RF GaN market is estimated at around $48 billion/year.
Accelerating reliability for automotive ICs
Accelerating reliability for automotive ICs, was presented by Edwin Chew, Manager, KLA Corp. Chip reliability is critical for vehicle safety and function. Chips need to work for long periods reliably. KLA’s broad portfolio enables process development and effective process control, especially across process, inspection, and metrology.
KLA has new features in plasma etching and plasma dicing. There are rounded trench bases required for next-generation power devices to improve gate oxide quality and prevent high fields. Novel, etch/passivation chemistry is an IP in progress. We are also doing plasma dicing of SiC, thereby, avoiding chipping. KLA has SPTS Delta PECVD for SiC devices. There is deposition of SiN, SiO, and TEOS SiO films.
Factors impacting SiC wafer yield include substrate quality, buffer quality, reactor cleanliness, etc. Candela 8520 is an unpatterned wafer defect characterization system from KLA. The tool uses multiple techniques for detection of growing library of defects at throughput for HVM. KLA offers step height metrology profilers as metrology solutions.
Strategy for growth in power and opto-electronics
Dr. Andy G. Sellars, Strategic Development Director and Founder, CSA Catapult, presented the strategy for growth in power and opto-electronics. Its vision is for the UK to become a global leader in developing and commercializing new apps for compound semiconductors.
The priority is on net zero and smart energy grids. EVs reduce CO2, and flexible grids store RE to manage peak demand. In future telecom networks, small cell base stations can deliver 5G. There is increased capacity for backhaul. Cube satellites are used for rural coverage and 5G corridors. There is cyber resilience and quantum capability.
Compound semiconductors outperform silicon in three areas — power, speed, and light. Net zero in transport and industrial, future telecoms in 5G, satellite and defense, and intelligent sensing are the major trends. Catapult has a 30,000sq ft facility in the UK.
The UK is now focusing on power electronics, RF/microwave, and photonics/quantum. All the three areas have strategic advantages. Net zero is critical for power electronics. UK can provide unique contributions that allow us to collaborate with others to achieve our goals. Areas of collaboration include CS die for hybrid integration, leading to system integration for net zero/energy. Also, there are Si and CS die for telecom, cyber and AI, CS die for space, etc.
SEMICON Taiwan 2022 Power & Opto Semiconductor Forum focuses on compound semiconductors
SEMICON Taiwan 2022 Power & Opto Semiconductor Forum | NExT Forum, was held today. The forum was co-organized by SEMI Taiwan and Hon Hai Research Institute.
Welcoming the audience, Brian Lee, Chief strategy Officer, Win Semiconductors Corp., said that we have been holding this forum for the last five years. The future technology and the apps are something that we have been keeping our eyes on.
Young Liu, Chairman, Hon Hai Technology Group (Foxconn), presented the keynote. With demand comes innovation. Hon Hai is looking at EVs, digital health, and robotics. Hon Hai Research Institute has strengthened its relationship with several universities. We have invested in TAISEC Material Corp. to strengthen the silicon carbide upstream supply chain and its long-term competitive advantage in automotive semiconductors. We need strong R&D and innovations.
Paths toward a greener future
Paths toward a greener future: Decarbonization with innovative silicon and WBG solutions, was presented by Gary Huang, MD, Infineon Technologies Taiwan Co. Ltd. We have so far achieved very little over the past 10 years. Wideband gap technology has also not caught up.
The long-term growth trends include decarbonization and digitization. Energy efficient solutions are increasingly relevant to deal with the world’s growth, and the resulting demand for energy. Infineon contributes to all CO2 saving measures to limit global warming as per the Paris Agreement. We provide fuel switch, energy efficiency, and renewable energies. Infineon provides solutions for all links in the energy value chain.
Our mission is to get more out of the sun. We are feeding electricity produced to the grid. We are enabling more, while using less electro-mobility, for energy consumption. On 5G, we are enabling more, using less. Infineon offers entire power flow for 5G. For data centers, we have solutions that support an improved system architecture.
Infineon’s wideband gap strategy is leveraging full potential based on power ratings and switching frequency required by app. SiC complements Si in many apps. GaN enables new horizons in power supply apps and audio fidelity. Si, SiC, and GaN capacity expansion is required to respond to fast-growing demand. Infineon has invested over Euro 2 billion in WBG production sites in Dresden, Germany, Villach, Austria, and Kulim and Melaka, Malaysia. Infineon offers CoolSiC and CoolGaN. Infineon has the broadest solution portfolio across SiC and GaN.
Compound semiconductors is not new. Infineon has been investing a lot, and reducing cost. Silicon is also reaching physical limitation. We are looking at new solutions.
Proliferation of GaN in data center and automotive
Proliferation of GaN in data center and automotive apps was presented by Stephen Coates, GM (Asia) and VP Operations, GaN Systems Inc. WBG is very important in semiconductors. Global electricity demand is growing 33 percent over the last decade, and will further grow 50 percent. We have three mega trends — digital economy, electrification, and energy efficiency. Data needs efficient power. We need fast charging and range. We have global focus on CO2 reduction. Consumers are demanding sustainability.
In 2021, there were over 10 billion active IoT devices, generating 20ZB of data. Autonomous cars will generate 40ZB of data per day. EV electrification will generate more data, with 65 million cars coming online by 2040. We have to relook at energy efficiency. 40 percent of electricity consumption will come from a renewable source in 2025. CO2 reduction improves the environment. There were large differences in air quality before and during Covid-19 lockdowns. Companies and governments are now stepping in. EC has data center lot 9 efficiency requirements required by 2023.
Transistors are critical components in power electronics. They are key, and have been the most important invention of the 20th century. Power electronics are constantly in need of higher efficiency, smaller size, lower system cost, and higher reliability. We need shift in transistor technology. Silicon transistors have reached maximum performance capabilities. GaN transistors perform better than silicon today, with lot of room for improvement.
GaN outperforms the other materials! It also drives significant value for customers, with 4x loss reduction, etc. Transistor performance improvement enables market disruption. GaN has tipping points, such as technological advancements and industry megatrends.
Key market segments include consumer, automotive, datacenter and 5G, industrial, and renewables. An example is EV on-board charger. We also have the motor/traction inverter, with a customer showing an all-GaN vehicle. Data centers are driven to higher performance, and higher power consumption. With GaN, data centers have more servers and storage per rack. GaN-based power supplies increase profits, reduce carbon emission, etc.
Extending benefits of GaN solutions
Luke Lee, President, Korea, Taiwan, and South Asia, Texas Instruments, presented on extending the benefits of GaN solutions from power delivery to other industrial apps. TI is going to have 6-10 new fabs in the future to support growth. Worldwide assembly and test expansion also supports growth.
Global trends are driving electrification, and increased focus on RE sources. Market trends are driving semiconductors. We are seeing shrinking form factors, increasing performance, extending reliability, and reducing cost.
Power delivery apps are seeing needs for higher power density, higher efficiency, etc. We are solving complex power delivery design challenges. The biggest challenge is reaching the higher power levels. We are moving from bridge rectifier to bridgeless topology to save bridge diode losses. We are moving to soft-switching converters for power density improvement.
Latest GaN devices are pushing the limits of power density and efficiency. We have real-time control MCUs that maximize GaN-based power solutions. We are enabling higher channel density and reduced AC/DC converter size in battery tester systems. TI is improving the tester channel density of the test equipment, and enabling faster power supply transient response time.
Power adapters are now addressing consumer needs. In solar and energy storage systems, we are achieving beyond 1.2-kW/L power density. We are reducing the energy dependency on the grid. TI has reference designs for power delivery and other industrial apps.
System designers are always striving for smaller systems with higher power density. GaN is pushing the limits of power density and efficiency.
Technological challenges for MOS HEMT GaN power devices
SEMI, USA, organized the Technology Week seminar. Day 1 focused on power electronics and devices. Ms. Veronique Sousa, CEA Leti, presented on the technological challenges for MOS HEMT (metal-oxide-semiconductor high-electron mobility transistor) GaN power devices.
There are wide band gap semiconductors. WBG and UWBG semiconductors are used for low-frequency unipolar vertical power switches. WBG apps range features SiC and GaN. SiC is quite mature. Looking at the long-term GaN power market evolution, GaN devices dominated the consumer market segment in 2018. By 2024, it will be introduced in the automotive market, and later, the industrial segment, by 2030. By this time, the industrial market will take off, and consumer and automotive markets will co-exist.
There are the N-ON GaN technologies. Examples are the P-GaN HEMT, hybrid drain GIT, and MOS HEMT GaN. P-GaN is in production at TSMC, and in R&D at IMEC. Hybrid drain GIT is in production at Panasonic and Infineon. MOS HEMT GaN is in R&D at ST/HRL, Toshiba, and Leti. Looking at the description of the main building blocks, there is epitaxy GaN on Si and passivation, recessed gate structure, and drain/source ohmic contact.
The pGaN FET architecture of devices is now available on the market for several “end-users” applications. CEA/LETI has develop another approach to meet the requirements of power electronics with an isolated MIS GATE HEMT GaN solution. This option is on its way to reach an industrial level of maturity.
A GaN-on-Si epitaxy has been developed. There are no holes for 10mm2 devices. As for DC device characteristics, there is positive Vth of 1.85V, but 500mV hysteresis is likely, due to the gate dielectric charge trapping.
There are technological challenges such as carbon contamimation. Yet another is gate trench etch. ALE process reduces the damage by conventional etching. There is the investigation of the etch impact on the trench profile after conventional etching and atomic layer etching. A new differential method allows to evaluate the contribution of the gate edge regions in the total MIS-HEMT device conductance. Another challenge is the wet clean before the high K deposition. There is the effect of the wet treatments prior to ALD of Al2O3.
We have shown the MOS-Gate stack. Ohmic contact on ALGaN/GaN is required. There is low resistive CMOS-compatible ohmic contact (Ti/Ai) on AlGaN/GaN. MOS gate HEMT GaN power devices have shown promising perspectives. Isolated gate provides its intrinsic benefits in terms of leakage and di-electric lifetimes. The ageing of gate stack should be pursued before starting reliability evaluation of the device.
Fabrication plant for power electronic SiP
Braham Ferreira, Prof., Power Electronics, Electrical Engineering, Mathematics & Computer Science, University of Twente, presented on fabrication plant for power electronic system-in-package (SiP), at the recently-held event on power and RF packaging. It was organized by Yole Développement, France, and Chip Integration Technology Center (CITC), The Netherlands.
Ferreira discussed a fabrication process for GaN heterogeneous integrated power modules. There is strong market growth for GaN. New-generation WBG (GaN and SiC) devices are potentially 100‐1,000 times faster and 100‐1,000 lower loss than today’s technology. GaN applications are used in power, RF and lighting. Market predictions for lateral GaN devices are very strong, heading rapidly to $1 billion.
He said that 5G needs GaN. From 4G to 5G, the power‐frequency product of cellular base stations increases 10x. At 400V, GaN offers the same high frequency performance as Si at 50V. At the same impedance, increasing voltage by 50, means, 400V yields 16x more power. Technology for packaging high voltage circuits is needed.
There is scope of HIPM. We target line connected power supplies. The power GaN industry focuses on packaging the active components in modules that we include transistors. The HIPM fabrication will include the passive components.
Power supply fabrication has somewhat stagnated. Passive components dominate size, weight and loss. Discrete components are soldered to PCB, and small profit margins are on passive components. The large parasitics due to multiple packaging layers makes it difficult to exploit the superior high frequency potential of GaN. Using parallel connection of small devices and capacitors 500V/ns has been reported.
Power supply miniaturisation is happening with GaN. The resistance per unit area of transistor chips is much higher compared to Si, as a result the efficiency is much higher. Lower resistance leads to higher efficiency. Lower switching losses makes it possible to reduce the size of passive components. Thru‐hole components can be replaced by SMT components.
More components, and higher power density is needed. University research
demonstrated advantages of hybrid conversion techniques. However, high component count means low reliability.
There is hidden secret in Moore’s Law. The scaling of early computer was impossible because of reliability limitations. High-quality circuit interconnection technology made high-component complex computing circuits possible. HIPM (host-initiated power management) makes 10x better reliability by fabricating all circuit inter-connections in one plant.
Let us look at the fabrication process for GaN heterogeneous integrated power modules. There is fab for diversity of converters in 20W-2kW power range. 3D converter is constructed from sandwiched organic substrates. System of copper and steel lead‐frames is required to create the optimal distribution of thermomechanical stresses, and to create cooling surface area for heat management.
In conclusion, the time is ripe, in view of the exponential growth of the power conversion and RF amplifier market, and the large forecasted production numbers, to invest in a dedicated power‐system‐in‐package fabrication platform. GaN power devices offer 10x potential improvement of “frequency x power” and power density.
However, this can only can be achieved if the suitable heterogenous integration fabrication technology can be developed. This can compete with the existing manufacturing technology a 10x better reliability is needed, which can be achieved by process quality control of interconnects under on roof, and optimize the (thermo‐) mechanical stresses of all interconnects.
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