{HEAD ~ The impurity layer} of high impurity concentration is formed between the first semiconductor substrate and {TAIL ~ the epitaxial layer} 
is formed between
{ HEAD ~ The impurity layer } of high impurity concentration is formed between the first semiconductor substrate and { TAIL ~ the epitaxial layer }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL REL REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL