| 摘要 |
<p>PURPOSE:To enable a narrower base width to be achieved by doping impurities whose diffusion coefficient is larger than that at other parts onto a part which is directly below a genuine base of a buried layer when forming a buried layer and by utilizing the plenomenon that the impurities with a larger diffusion coefficient are raised by later heat treatment. CONSTITUTION:When doping impurities of an N<+> buried layer 2a for a P sub strate 1, impurities with a larger diffusion coefficient than that at other parts are doped at a part which is directly below a genuine base and an epitaxial layer 4 is allowed to grow on it, thus forming a separation diffusion layer 3 for element separation. The impurities with a larger diffusion coefficient which are doped directly below the genuine base of the N<+> buried layer 2a is raised as shown in figure by later heat treatment, thus suppressing diffusion of boron ion at the genuine base part of a base diffusion layer 5 due to implanta tion of boron ion, enabling impurity distribution to be sharp, and helping to achieve a narrow base width.</p> |
