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Abstract: This work will focus on the use of Selective Epitaxial Growth (SEG) of Si and SiGe in multi-gate devices. We will demonstrate the necessity of using SEG in the processing of these narrow fin devices. Reductions of the source/drain resistance and Gate Induced Drain Leakage (GIDL) are the main advantages of using SEG. Although the use of SiGe SEG has little impact as mobility booster in narrow fin pMOS devices, it provides a significant reduction in contact resistance. [Copyright &y& Elsevier]

Typical contacts to n-Ge result in high specific contact resistivity (ρC) or rectifying behaviour due to Fermi level pinning (resulting in high barrier heights) and low dopant activation generally observed for n-Ge. In this work, we fabricated and studied ohmic contacts to n-type Ge prepared by Ni germanidation of samples with As ion implantation for two different approaches: (1) dopant activation by sub-melt laser anneal (LA) prior to germanidation and (2) Snowplow, i.e., dopant segregation during Ni germanidation without previous thermal activation. Low resistivity ohmic contacts of 8 × 10-7 Ω cm2 for LA and 2 × 10-5 Ω cm2 for Snowplow were obtained using circular transfer length method to determine ρC. We show contacts to be thermally stable to 350 °C. Furthermore, by studying the temperature dependence of ρC, we clarify that the underlying cause of the low contact resistivity for both approaches is the high active dopant concentration obtained. We find the results in both cases to be consistent with the thermionic field-emission mechanism for a barrier height of 0.75 eV and with active dopant concentrations of 3 × 1019 cm-3 for LA and 1.5 × 1019 cm-3 for Snowplow samples. [ABSTRACT FROM AUTHOR]

We report on the study of the electrical and material properties of n-Ge contacts with a thin Si-passivation layer. n-Ge contacts typically show Fermi-level pinning and low dopant activation which results in too large specific contact resistivities of >10-4 Ω cm2 and which impedes applications such as high performance Ge complementary metal-oxide semiconductor technology. In this work a thin in situ doped (1×1020 cm-3 of phosphorus) epitaxial Si-passivation layer is grown selectively on n-Ge, followed by a Ti/TiN stack deposition. The insertion of this thin Si-passivation layer reduces the pinning and activation limitation, achieving specific contact resistivity values of ∼1×10-6 Ω cm2. Physical modeling of the specific contact resistivities was performed, providing the insight validating the underlying explanation of the improvement. Key factors for the contact resistivity lowering are the good alignment of the Si and Ge conduction bands and the higher doping concentration achieved in Si. [ABSTRACT FROM AUTHOR]