Improved Thermal Performance of SOI Using a Compound Buried Layer

The buried oxide (BOX) layer in silicon on insulator (SOI) was replaced by a compound buried layer (CBL) containing layers of SiO 2 , polycrystalline silicon (polysilicon), and SiO 2 . The undoped polysilicon in the CBL acted as a dielectric with a higher thermal conductivity than SiO 2 . CBL provid...

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Veröffentlicht in:IEEE transactions on electron devices 2014-06, Vol.61 (6), p.1999-2006
Hauptverfasser: Baine, Paul, Montgomery, John H., Armstrong, B. Mervyn, Gamble, Harold S., Harrington, Sarah J., Nigrin, Sydney, Wilson, Robin, Oo, Kean B., Armstrong, Alastair G., Suder, Suli
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Sprache:eng
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Zusammenfassung:The buried oxide (BOX) layer in silicon on insulator (SOI) was replaced by a compound buried layer (CBL) containing layers of SiO 2 , polycrystalline silicon (polysilicon), and SiO 2 . The undoped polysilicon in the CBL acted as a dielectric with a higher thermal conductivity than SiO 2 . CBL provides a reduced thermal resistance with the same equivalent oxide thickness as a standard SiO 2 buried layer. Thermal resistance was further reduced by lateral heat flow through the polysilicon. Reduction in thermal resistance by up to 68% was observed, dependent on polysilicon thickness. CBL SOI substrates were designed and manufactured to achieve a 40% reduction in thermal resistance compared with an 1.0-μm SiO 2 BOX. Power bipolar transistors with an active silicon layer thickness of 13.5 μm manufactured on CBL SOI substrates showed a 5%-17% reduction in thermal resistance compared with the standard SOI. This reduction was dependent on transistor layout geometry. Between 65% and 90% of the heat flow from these power transistors is laterally through the thick active silicon layer. Analysis confirmed that CBL SOI provided a 40% reduction in the vertical path thermal resistance. Devices employing thinner active silicon layers will achieve the greater benefit from reduction in vertical path thermal resistance offered by CBL SOI.
ISSN:0018-9383
1557-9646
DOI:10.1109/TED.2014.2318832