Research in Focus
Enhanced properties from combined SiGe and InP circuits
FBH and IHP from Frankfurt/Oder successfully combined SiGe-based BiCMOS and InP-based circuits by integrating them on one chip. Thus, new ambitious applications in the THz range are within reach including high-resolution imaging systems for medical and security technology as well as ultra-broadband mobile communication applications. At the frequency range around 100 GHz and beyond the breakdown voltage in CMOS circuits decreases, and accordingly the available output power degrades.
However, the novel material combination delivers the desired properties: high output power at high frequency. The independently preprocessed BiCMOS and InP wafers are arranged sandwich-like and bonded with few-micrometer precision on top of each other. This approach keeps all benefits both from the high level of production routine and integration of BiCMOS circuits and from the excellent InP material properties. InP double heterojunction bipolar transistors on top of BiCMOS demonstrate record high-frequency characteristics with transit frequencies ft and fmax of 400 and 350 GHz delivering an output power of more than 26 mW at 96 GHz. Next steps aim at further stabilizing the process and optimizing the circuits. This way, the synergy potential created by combining both complementary semiconductor technologies shall be exploited to reach a performance level beyond the individual limits.
M. Lisker, A. Trusch, M. Fraschke, P. Kulse, Y. Borokhovych, B. Tillack, I. Ostermay, T. Krämer, F.J. Schmückle, O. Krüger, V. Krozer, W. Heinrich, "InP-Si BiCMOS Hetero Integration for broadband radio links", Smart Systems Integration, Amsterdam (2013).
Related press release:
Outlook – presentations in 2013:
- M. Lisker, A. Trusch, A. Krüger, M. Fraschke, P. Kulse, Y. Borokhovych (IHP), B. Tillack (IHP, TU Berlin), and I. Ostermay, T. Krämer, A. Thies, F.J. Schmückle, O. Krüger, V. Krozer, W. Heinrich (FBH), "InP-Si BiCMOS Heterointegration Using a Substrate Transfer Process", accepted for presentation at ECS Meeting 2013, Toronto, May 12-16, 2013.
- I. Ostermay, F.J. Schmückle, R. Doerner, A. Thies, M. Lisker, A. Trusch, E. Matthus, Y. Borokhovych, B. Tillack, W. Heinrich, T. Kraemer, V. Krozer, O. Krüger, T. Jensen, "220 GHz Interconnects for InP HBT on SiGe BiCMOS Integration", accepted for presentation at IMS 2013, Seattle, June 2013.
- T. Jensen, T. Al-Sawaf, M. Lisker, S. Glisic, M. Elkhouly, T. Kraemer, I. Ostermay, C. Meliani, B. Tillack, V. Krozer, W. Heinrich, "A 164 GHz Hetero-Integrated Source in InP-on-BiCMOS Technology", accepted for presentation at EuMC 2013, October 2013.
Microresonators of utmost quality for high-precision applications
FBH and HU Berlin joined forces to advance high-quality optical microresonators. The tiny structures range from 50 µm - 500 µm in diameter with a thickness of about 1 - 2 µm. They can be assembled as compact and robust optical systems that may be tailored precisely and flexibly according to the requirements of the respective application.
The optical resonators investigated are silica disks that guide and store light in so-called "whispering gallery modes". Due to the excellent optical properties of the material and an elaborated process technology, light can be stored long enough to enable optical resonators with a linewidth of only a few 100 MHz. This feature is attractive for various applications, such as short-pulse light sources, spectrometers, and optical sensors. The laser metrology group has developed a test stand for optical characterization of such microresonators in the wavelength range of 765 - 781 nm. In the setup, the distance between a tapered fiber and the optical resonator can be controlled with a precision better than 10 nm; resonance frequencies and Q-factors can be measured automatically with high precision and reproducibility.
R. Henze, C. Pyrlik, A. Thies, J. M. Ward, A. Wicht, O. Benson, "Fine-tuning of whispering gallery modes in on-chip silica microdisk resonators within a full spectral range", Appl. Phys. Lett. 102, 041104, doi: 10.1063/1.4789755, (2013).
J. Ward, R. Henze, M. Gregor, C. Pyrlik, A. Wicht, A. Thies, A. Peters, S. N. Chormaic, O. Benson, "Integrated Whispering-Gallery Mode Resonators for Fundamental Physics and Sensing Applications", Laser Resonators, Microresonators, and Beam Control XIV, edited by A. V. Kudryashov, A. H. Paxton, V. S. Ilchenko, L. Aschke, K. Washio, Proc. of SPIE Vol. 8236, 82361C, doi: 10.1117/12.914712, (2012).
Thin film coating at atmospheric pressure
Many surfaces require surface treatment including flat-panel displays, mobile phones, and eye glasses. FBH developed a novel patented atmospheric source allowing sputter deposition of thin films at atmospheric pressure. So far, for this process bulky and costly vacuum coaters were used. The treatment has now been successfully transferred to ambient air thus enabling substantial cost reduction by eliminating expensive vacuum technology. It additionally opens up entirely new coating applications. Combining the microwave plasma with a dc current for ion extraction leads to stable operation and thus enables the desired thin film deposition. Up to now, even experts considered this process impossible. Due to the great market opportunities of this invention, a spin-off to commercialize the technology is currently being prepared.
The FBH prototype operates with a microwave resonator at 2.45 GHz driven by a solid-state transistor oscillator. Inert gases at flow rates of 25 - 100 l/h are ionized by microwave energy. An additionally applied dc voltage of > 100 V, delivering a current of approximately 100 mA, extracts ions from the plasma and accelerates them towards the target. Thus, a sputter process takes place at atmospheric pressure. Au films can be deposited with a sputtering rate of 30 nm / min. on an area of 5 mm2.
More: frequent (in German) on plasma sources (issue 2010)
R. Bussiahn, R. Gesche, S. Kühn and K.-D. Weltmann, "Integrated Microwave Atmospheric Plasma Source (IMAPlaS): thermal and spectroscopic properties and antimicrobial effect on B. atrophaeus spores", Plasma Sources Sci. Technol., vol. 21, no. 065011 (2012).
J. Liebmann, J. Scherer, N. Bibinov, P. Rajasekaran, R. Kovacs, R. Gesche, P. Awakowicz, V. Kolb-Bachofen, "Biological effects of nitric oxide generated by an atmospheric pressure gas-plasma on human skin cells", Nitric Oxide, vol. 24, no. 1, pp. 8-16 (2011).