Low-Stress Highly-Conductive In-Situ Boron Doped Ge_(0.7)Si_(0.3) Films by LPCVD

摘要

This paper reports on low pressure chemical vapor deposited in-situ boron doped polycrystalline germanium-silicon layers with 70% germanium content. The effect of diborane partial pressure on the properties of the GeSi alloy is investigated. The obtained high boron concentration results in resistivity values less than 1 mQ-cm. The layers deposited at low partial pressures of B_2H_6 exhibit very low stress down to -3 MPa. With increasing B_2H_6 partial pressure first the stress changes from tensile to compressive, followed by a phase transition from polycrystalline to amorphous. The highly doped, low stress poly-Ge_(0.7)Si_(0.3) layers deposited at 430°C are further applied in high-Q microelectromechanical resonators envisaged for above-IC integration with CMOS.