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Stability evaluation of Au-free Ohmic contacts on AlGaN/GaN HEMTs under a constant current stress.
- Source :
-
Microelectronics Reliability . Sep2014, Vol. 54 Issue 9/10, p2232-2236. 5p. - Publication Year :
- 2014
-
Abstract
- The reliability of Au-free Ohmic contacts has been evaluated under a constant current stress (500 mA/mm) in a high temperature environment (150 °C, 175 °C, and 200 °C). Two Ohmic contact schemes with different Ti/Al thicknesses (5 nm/100 nm and 10 nm/100 nm) have been tested. The results showed that the degradation of the resistance ( R increase ) is accelerated at a higher temperature condition. Moreover, R increase has a square root dependence with the time. This indicates that a diffusion process could be responsible for the observed degradation. This has been confirmed by means of physical failure analyses (FIB/TEM) performed on a highly degraded device: an apparent roughness of the interface between TiN and the Ohmic metal layer was observed. On top of this, Nitrogen out-diffusion into the Ohmic metal was observed in the EDS/EELS analyses, suggesting that a material diffusion phenomenon might play a role. In addition, we observed that the devices with a lower initial contact resistance ( R c ) showed lower degradation with respect to devices with a larger initial R c . This suggests that obtaining lower R c is beneficial not only for the performance but also for the reliability. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00262714
- Volume :
- 54
- Issue :
- 9/10
- Database :
- Academic Search Index
- Journal :
- Microelectronics Reliability
- Publication Type :
- Academic Journal
- Accession number :
- 99231970
- Full Text :
- https://doi.org/10.1016/j.microrel.2014.07.076