Renaud Bonzom

New interface state density extraction method applicable to peaked and high-density distributions for Ge MOSFET development

A method for extracting parameters of weakly Fermi-level pinned germanium (Ge) capacitors is introduced. This method makes progress toward a more generally valid reliable interface state parameter extraction. Such a general method is needed to evaluate and explain the behavior of Ge MOS capacitors, which show characteristics deviating considerably from silicon. The encountered weak pinning confirmed by the new extraction method explains the degraded Ge nMOSFET performance.

In Situ Phosphorus Doping of Germanium by APCVD

Germanium is increasingly being studied for application in advanced nanoelectronic devices, due to its high intrinsic carrier mobility. While broad knowledge and understanding of in-situ doping of Si is available, very little is known on in-situ doping of Ge. Phosphorus has been identified as one of the most promising n-type dopants for Ge, because of its high electrical activity. However, studies of the quality of ion-implanted P-doped Ge layers showed unsatisfactory behavior. A considerable difference between the levels of the electrical solubility and equilibrium solid solubility of P in Ge has been reported. The highest electrically active level of ionimplanted P in Ge reported to date is of 5-6×10 cm. The interest in in-situ doping of Ge was triggered by the possibility of increasing the electrically active levels obtained for n-type dopants at the same time as having better control over the shape of the dopant profile and its location. We present the first results on in-situ P doping of Ge by APCVD.

How trace analytical techniques contribute to the research and development of Ge and III/V semiconductor devices

The scaling of microelectronic transistors to ever-smaller dimensions has ultimately pushed the Si based materials to its physical limits. For the gate stack, dielectric materials with a higher dielectric constant κ than the conventional SiO2 are required. Further, high mobility channels are implemented (strained silicon), but are likely to be replaced on the longer term by the intrinsic higher mobility substrates such as Ge or III/V compound semiconductors (GaAs, GaN, InP,..). The introduction of these new substrates requires a reengineering of the standard IC processes with substantial efforts through research and development programs. In this paper, we demonstrate how the trace analytical techniques of total reflection X-ray fluorescence spectrometry (TXRF) and atomic absorption spectrometry (AAS) contribute to the realization of suitable processes at different stages of the process flow on Ge and GaAs substrates.