Thermal Stability of TiN/Ti/p+-Si0.3Ge0.7 Contact With Ultralow Contact Resistivity

In this letter, the contact properties and thermal stability of TiN/Ti/p⁺ -Si_0.3Ge_0.7 contacts are investigated. We demonstrate that the insertion of an ultra-thin Ti interlayer is necessary to reduce the contact resistivity (ρc) as compared with a standard TiN/p⁺-Si_0.3Ge_0.7 direct contact. However, the Ti interlayer has to be thin enough to avoid degradation of the contact morphology after 500 °C annealing. This letter reveals further that the Ti encroachment into grooved SiGe regions under the contact interface is responsible for the ρ_c increase seen after this annealing.