1. Technical Field
The present invention relates to a method for manufacturing a semiconductor device, especially a method for manufacturing a semiconductor device, as well as a semiconductor substrate, that can reduce the possibility of, for example, crystal defects occurring from an element isolation region.
2. Related Art
In a method for manufacturing a semiconductor device having an element isolation region, especially a high-breakdown-voltage transistor, an element isolation region is formed on a semiconductor substrate first, and then a well is formed by introducing an impurity into an element-forming region, which is the region other than the element isolation region, and performing a long-time heat treatment for uniform diffusion of the impurity within a desired region on the semiconductor substrate, as disclosed in JP-A-2004-260073, which is an example of related art.
In the above method, however, a heat stress is applied due to the heat treatment that is performed in forming a well on a semiconductor substrate on which an element isolation region is formed. Such a heat stress can cause problems of crystal defects, as well as cracks due to, for example, the concentration of such crystal defects.