German-based AZZURRO Semiconductors, a leading provider of high-quality GaN-on-Si Epi wafers, announced that, the company has successfully achieved superior electrical performance and established a volume production track record for large size high voltage wafers. It is expected that this leading production technology will drive a new wave of demands for the high performance and cost-effective power devices.
According to Erwin Ysewijn, VP Sales and Marketing of AZZURRO, under the mega trend of energy-saving, the power efficiency requirement for various electronic devices is getting higher, and the new applications, such as electrical vehicles and smart grid, will also drive the new demands for high voltage semiconductor market.
Unlike silicon material, which has inherent limitations for fast switching at high voltage, GaN can meet these performance requirements with its excellent breakdown voltage and low leakage characteristics. At present, the availability in the industry is still limited for production suitable 6" (150 mm) wafers to fabricate GaN High voltage devices. AZZURRO's large-size GaN-on-Si technology will help customers boost the cost effectiveness of power devices to next level.
"By adopting GaN-on-Si technology, it is possible to develop power semiconductors up to 1700V, whereas our target market currently is 600 V", Ysewijn said. "It can replace current solutions across a broad range of power levels and targets various applications, such as hybrid and electric vehicles, solar and power supplies, SMPS (switched mode power supply), PFC (power factor corrector), and SFC (static frequency converters/inverters). Also, because GaN has higher switching speed, it can further realize the design goals of system miniaturization and cost-down."
GaN-on-Si has significant advantages, it will see the initial adopted phase by the industryin 2014, technical difficulties have been overcome at AZZURRO. The main challenge was how to overcome the bows and cracks that are formed during manufacturing process. These defects are resulted from the different thermal expansion coefficients between the silicon substrate and GaN layers.
After successful completing the first runs for GaN-on-Si at lab in 2003, AZZURRO already have accumulated around ten years of experiences in this technology. The company began pilot production in 2009 and continuously improved reproducibility. After that, two production lines were set up in Dresden in 2011 and moved to volume manufacturing in 2012, as well as transfer technology to multiwafer tool.
"AZZURRO can address the industries requirements, today!" Ysewijn stressed.
He explained that factory requires large diameter GaN-on-Si technology for mass production, and the technology must be CMOS friendly, so that they can use standard silicon foundries. The most importantly, we need to help customers produce wafers with stress free and low bow wafers to meet their quality requirements.
"AZZURRO now can address large diameter (up to 200mm) GaN-on-Si technology. With own patented interlayers process, we can grow thick buffer layers on silicon substrates to achieve best crystal quality and excellent device performance."
Thickness homogeneity is also important for high voltage devices, which have stricter requirements on breakdown voltage and leakage for each device manufactured on the wafer. AZZURRO's patented technology can achieve superior homogeneity for yield breakthroughs, and is ready for standard silicon process lines.
"In order to adopt existing CMOS lines, it is required that the GaN-on-Si wafer should be lower than 50μm", Ysewijn said. "Our production results show that bow is excellent managed per wafer, as well as per run. Take 150mm wafer as an example, AZZURRO can grow 6μm thick GaN layer with only 1.4% deviation of uniformity."
In terms of material quality, AZZURRO can also achieve superior low tilt, twist, and defect level, with smooth and crack-free surface. As for leakage performance, the leakage current at 1000V is less than 100 nA/mm. Also, it also shows excellent breakdown characteristics regardless of gate width up to 100mm.
Moreover, for 200mm GaN-on-Si HEMT wafers with breakdown voltage large than 600V, the result shows that wafers with total thickness of 5.6μm are crack-free and have wafer bow lower than 20μm.
"It's a quantum leap in material quality and device performance for large-size GaN-on-Si wafers with yield rate up to more than 70%, average size devices are meeting yields close to 90%." Ysewijn stressed. With high volume support capabilities, proven reproducibility and SPC data, AZZURRO will take the lead to drive the broad adoption of its leading GaN-on-Si technology and bring more innovative applications for high voltage semiconductor market.
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