awk -v s1="\"" 'match($0,/"[a-zA-Z]+\;.*\"/){num=split(substr($0,RSTART+1,RLENGTH-1),array,";");for(i=1;i<=num;i++){print substr($0,1,RSTART-1) s1 array[i] s1}}'  Input_file

awk -v s1="\"" '
match($0, /"[a-zA-Z]+\;.*\"/) {
  num = split(substr($0, RSTART + 1, RLENGTH - 1), array, ";");
  val = substr($0,1,RSTART - 1);
  for (i = 1; i <= num; i++) {
    print val s1 array[i] s1
  }
}
'   Input_file

awk -F, '
        {gsub (/;/, "\"&\"", $3)
         n = split ($3, T, ";")
         for (i=1; i<=n; i++)   {$3 = T[i]
                                 print
                                }
        }
' OFS=, file