| 摘要 |
PURPOSE: A method for fabricating a bipolar junction transistor is provided to prevent contamination by trapping metal impurity through contamination prevention areas formed under an N-type epi layer. CONSTITUTION: A first contamination prevention area(14a) is formed in a semiconductor substrate by first ion implantation. A second contamination prevention area(14b) is formed in a first contamination prevention area by secondary ion injection. A second conductive epi layer is formed by injecting second conductive impurity ion in the second contamination prevention area. A collector area, a base area and an emitter area(26) of second conductive type are formed in the semiconductor substrate. An emitter(30) and a collector(32) are formed in the collector area and the emitter area by injecting second conductive impurity ion. A base(40) is formed by injecting first conductive impurity ion in the semiconductor substrate.
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