Low Temperature Atmospheric Pressure Chemical Vapor Deposition for Epitaxial Growth of SiGe Bipolar Transistors

Atmospheric pressure chemical v por deposition (APCVD) has been used to grow an epitaxial SiGe-base for a novel self-aligned low thermal budget heterojunction bipolar transistor (HBT) device. The hydrogen growth ambient is shown to greatly facilitate the growth of high quality epitaxial layers in the range 550 to 750 ~ SiGe was deposited from silane, germane, and diborane using gas witching. Convenient growth rates were achieved with SiGe alloy compositions of 10 to o 1.7 19 3 30 '/o Ge and 10 to 10 /era p-type doping. The SiGe-base region was a.box-shaped profile about 60 am wide with a narrow boron spike nested inside. The Gumme] characteristics of transistors were ideal indicating high quality material, and the devices had excellent ac characteristics which have been reported elsewhere