VARACTOR WITH IMPROVED G-FACTOR CHARACTERISTIC USING SIGE HETEROJUCNTION BIPOLAR TRANSISTOR AND METHOD FOR FABRICATING THE SAME

摘要

PURPOSE: A varactor and a method for fabricating the same are provided to keep the q-factor characteristic in a good condition by using SiGe hetero junction bipolar transistor whose phase noise characteristic is better than others. CONSTITUTION: A n+ type buried collector region(301) is formed in a p type semiconductor substrate(300). A n type collector and n+ type collector contact region(302,303) are placed apart from each other by a device isolation layer(304). A p+ type external base region(315) is formed on the n type collector contact region. A p+ type SiGe base region(305) is formed on the p+ type external base region. A metal silicide layer(312) is formed on the p+ type SiGe base region(305). The first meal layer(309) formed on the exposed portion of the metal silicide layer is used as an anode electrode. A n+ type poly silicon layer(307) and metal silicide layer(312) are formed on the n+ type collector contact region in a sequence. The second metal layer formed on the exposed part of the metal silicide layer is used as a cathode electrode.