| 摘要 |
PURPOSE: A bipolar transistor having improved electrodes with low resistance that can prevent advancement of corrosion is provided. CONSTITUTION: In the bipolar transistor, an epitaxial layer(300) is formed as a collector region on a substrate(100), and a collector electrode(200) is formed under the substrate(100). In addition, a base region(400) is formed in an upper part of the epitaxial layer(300), and an emitter region(500) is formed in the base region(400). The epitaxial layer(300) is covered with an insulating layer(700) having openings exposing the base region(400) and the emitter region(500). A base electrode(420) and an emitter electrode(520) are formed in the respective openings. In particular, each of the base electrode(420) and the emitter electrode(520) has a lower conductive layer(421,521) made of aluminum and an upper conductive layer(423,523) made of copper. Further, a buffer layer(422,522) made of metals such as chromium or titanium may be formed therebetween to enhance contact property. An oxidation barrier such as silver may be coated on the upper conductive layer(423,523).
|
