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Investigating the impact of etching time on 4H-SiC defects

Posted: 31 Mar 2016 ?? ?Print Version ?Bookmark and Share

Keywords:Silicon carbide? SiC? etching time? stacking faults? photoluminescence?

The charts in figure 4 show the increase in step bunching number (left) and uniformity (right). In detail, figure 4 (left) shows an increase in the number of step bunching as a function of the etching time. The measure of the number is an average of different measurements performed in a different wafer zone. From such measurements, a difference in terms of step bunching wafer uniformity (sigma/mean) was observed along the wafer. Increasing the etching time and worsening of the uniformity was evaluated. For instance, in x3 sample there is a zone with high density of step bunching, while x0.5 is more uniform (about 2 step bunching in every part of the wafer analysed).

Figure 4: Step bunching number (left) and uniformity (right).

Conclusion
In this article, we looked into the relationship between the pre-growth H2 etching time and defects density. With photoluminescence and optical analysis, we detected increase in stacking faults and surface defects in the epi-layer as etching time increases. Such increase in time produces an enlargement of the substrate dislocation that boosts the likelihood of defects in epi-layer. AFM analysis also shows the rise in step bunching density and uniformity with the increase in H2 surface etching.

References
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About the authors


Marco Salanitri
STMicroelectronics
Marco joined the STMicroelectronics in June 1999, where he worked on Front End Manufacturing. In 2004, he joined STMicroelectronics R&D Group where he worked on PEM-Fuel Cell. His research concerned the development of Hydrogen on Demand Fuel Cell and polymeric materials for Proton Exchange Membrane. Since 2013, he worked on epitaxy growth process. His research interests include 3C-SiC hetero-epitaxy process development on Si and 4H-SiC homo-epitaxy for semiconductor applications. He received B.S. degree in Chemistry in April 1999 from the University of Catania, Italy.

Ruggero Anzalone
STMicroelectronics
Ruggero Anzalone, Ph.D, received his B.S. degree in Physics in July 2005 and Ph.D. degree in material science in March 2010 from the University of Catania, Italy. His Ph.D. work was focused on the silicon carbide (3C每SiC) growth process and its applications. In October 2005, he joined the Frascati Research Centre (ENEA) in Rome, Italy, where he worked on inertial fusion confinement. In 2011, he has held a postdoctoral post at the CNR每IMM of Catania. His research interests include the development of hetero-epitaxial 3C-SiC process. In 2013, he joined the Epitaxial Tech. Centre where he worked on the SiC process development. Since 2014, he has been working in STMicroelectronics as 4H-SiC and 3C-SiC Process Engineer in the R&D group.

Simona Lorenti
STMicroelectronics
Simona Lorenti received the B.S. degree in industrial chemistry in July 1997 from the University of Catania. In 1998, she joined STMicroelectronics in 1998 as Si epitaxy and diffusion Process Engineer, working in the R&D group. From 2004 to 2007, she worked on photovoltaic process, and then from 2008 she has been involved in compound semiconductor matter, responsible for SiC and GaN epitaxy and diffusion group. Her research work include the development of homoepitaxial 4H-SiC epitaxy, hetero-epitaxial GaN process, high temperature dopant activation in SiC, and gate processes for SiC devices.


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