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