| 摘要 |
<p>PURPOSE:To improve breakdown resistance and hence improve high frequency characteristics by allowing a depletion layer to spread into also a p<+> layer as steep reverse voltage is applied thereto by lowering an impurity concentration gradient in the vicinity of a pn junction between an n base layer and the p<+> layer. CONSTITUTION:An n type silicon substrate having a predetermined specific resistance is used, from one surface of which substrate an acceptor impurity is diffused to four a depth d1 p<+> layer and from the other surface of which a donor impurity is diffused to form an n<+> layer. Herein, impurity concentration of the n base layer without diffusion of the impurity is 10<14>/cm<2>. Since a diffusion concentration gradient in the vicinity of a pn junction is progressive as a concentration ratio being 15 times/1mum or less, a depletion layer spreads not only into the n base layer but also into the p<+> diffusion layer even if steep voltage is applied thereto. Therefore, an electric filed intensity is correspondingly reduced to improve breakdown resistance. Thus, the thickness of the n ba layer can be thinned to improve high frequency performance. Hereby, high frequency performance can be improved and steep reverse voltage resistance can be prevented from lowering.</p> |
