use more coherent names

template_phd.cls

@@ -390,7 +390,7 @@
   \put(0,0){%
     \parbox[t][\paperheight]{\paperwidth}{%
       \vspace{-33.1cm}
-      \input{./cover/backcover_tikz}
+      \input{./cover/cover_back_tikz}
   }}
 }
 \hspace{9mm}