Properties of SiO₂ Films Deposited at low Temperature and Their Application in the Fabrication of SiGe/Si HBT

SiO₂ films used for passivation in the fabrication of mesa SiGe/Si HBTs were deposited by sputtering. The influence of the sputtering procedure on the propenties of the films and the performance of the HBTs was discussed. As it turned out that higher substrate temperature is favorable to the quality of the films. The electric current gain of the HBT with SiO₂ deposited by sputtering is much higher than those deposited by thermal decomposition owing to that the former approach avoids the strain relaxation caused by high temperature procedure which would result in the degradation of the HBT performance.