Diode Characteristics and Thermal Donor Formation in Germanium-Doped Silicon Substrates

Abstract

Germanium-doped silicon is studied actively for application in microelectronics, in particular, as an improvement of the radiation hardness of the silicon substrate can be achieved. However, the impact of the introduced germanium on the electrical stability and properties of the silicon material and devices is also of special concern. In this contribution we report the results of a study on the effects of low temperature thermal anneals relevant for backend processing, on the electrical characteristics of p-on-n diodes fabricated on Czochralski-grown (CZ) Ge-doped-Si with two different germanium concentrations (1•1019 cm-3 and 1.2•1020 cm-3), as well as on control CZ Si wafers without Ge doping. The results show good diode yield and uniformity, with little differences between the electrical characteristics of the fabricated diodes on the different substrates. However, interestingly for device applications, a significantly lower thermal donor generation (by one order of magnitude) is found for the case of the higher Ge-doped material subjected to 450ºC thermal anneals.