Reliability investigation in SiGe HBT’s

This paper addresses some reliability properties of SiGe HBTs. We first verified that no major problems were related to the SiGe layer through DC life tests. In the second step, we investigated the hot carrier influence on the DC, noise and microwave properties of these devices. We found that some degradation was occurring at the extrinsic base region in the vicinity of the emitter associated with some surface recombination. These assumptions have been described by physical simulations and confirmed by low frequency noise characterization. Finally, it has been demonstrated that microwave properties are affected by the mechanism and we propose a bias method that results in its minimization