| 摘要 |
As an element of an integrated circuit, an npn bipolar transistor is manufactured as usual in a transistor area covered on a semeconductor substrate with a portion of a field oxide layer by forming openings through the layer portion and forming a highly n-doped collector lead, a highly p-doped base contact region, and then a highly n-doped emitter region. A field oxide film unavoidably remains at a bottom of one of the openings that is directed to the base contact region. This is because p-type impurity ions are injected through the field oxide film on forming the base contact region. Either by thermal oxdization or by injection of oxygen ions, the field oxide film is given a high or excessive oxygen content. It now becomes possible to completely remove the field oxide film by chemical etch, as by hydrofluoric acid, and to bring an electrode into execellent ohmic contact with the base contact region. This method is equally well applicable to manufacture of a pnp bipolar transistor in completely removing field oxide films which inevitably remain in the openings directed to highly p-doped collector lead and emitter region.
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