Comparison of Ti/Pt/Au and Ti/Ru/Au contact systems to p-type InGaP
V. Malina1, K. Vogel2, P. Ressel2, W.O. Barnard3, A. Knauer2
Published in:
Semicond. Sci. Technol., vol. 12, no. 10, pp. 1298-1303 (1997).
Abstract:
The electrical and metallurgical properties of vacuum-evaporated Ti/Pt/Au and Ti/Ru/Au contacts to moderately doped p-type InGaP (p ∼ 3 × 1018 cm−3) and their thermal stability at higher temperatures are reported. Ohmic behaviour and typical contact resistivities of 4–6 × 10−5 and 6–11 × 10−5 cm2 could be obtained only for contacts annealed between 500 and 600 °C. When subjected to an aging test at 300 °C for 50 h in N2, the contacts originally annealed at 500 °C exhibited good electrical stability and only a minor increase of the specific contact resistance was observed during the first 25 h. SEM observation of surface morphology and SIMS in-depth profile measurements showed that the Ru layer, incorporated between the Ti contact layer and a thick Au top layer, proved to be a more effective and thermally more stable diffusion barrier than the Pt layer. As a result, the standard Ti/Pt/Au contacts were metallurgically stable up to 550 °C, while the newly proposed Ti/Ru/Au contact scheme exhibited a remarkable stability even after annealing at 600 °C.
1 Institute of Radio Engineering and Electronics, Czech Academy of Sciences, Chaberska 57, CZ-18251 Prague 8, Czech Republic
2 Ferdinand-Braun-Institut für Höchstfrequenztechnik, Rudower Chaussee 5, D-12489 Berlin, Germany
3 University of Pretoria, Department of Physics, Pretoria 0002, Republic of South Africa
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