| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain an IGBT whose safe operation region, short-circuit strength and latch-up phenomenon are improved by a method, wherein high concentration impurity ions are implanted into the whole surface of a substrate on which a low impurity concentration 1st epitaxial layer is built up and, after a low impurity concentration 2nd epitaxial layer is built up, the substrate is subjected to a heat treatment, etc. SOLUTION: After a 1st epitaxial layer 42 containing low concentration 1st conductivity-type impurities is built up on a silicon substrate 41, high concentration 1st conductivity-type impurities 44 are introduced into the whole surface of the 1st epitaxial layer. After a 2nd epitaxial layer 45 containing low concentration 1st conductivity-type impurities has been built up, the substrate is subjected to a heat treatment, in order to adjust the gradient of the concentration of the high concentration 1st conductivity-type impurities introduced into the 1st epitaxial layer 42. Thus, a semiconductor substrate for forming an IGBT is manufactured. For instance, a thin low concentration N-type 1st epitaxial layer 42 is built up on a P<+> -type silicon substrate 41, and ions of high concentration N-type impurities 44 are implanted by using a thermally oxided film 43 as a mask.</p> |
