A method for forming a foreign oxide or foreign nitride layer (6) on a substrate (1) of a semiconductor comprises providing a semiconductor substrate (1) having an oxidized or nitridized surface layer (3), supplying a foreign element (5) on the oxidized or nitridized surface layer; and keeping the oxidized or nitridized surface layer (3) at an elevated temperature so as to oxidize or nitridize at least partially the foreign element by the oxygen or nitrogen, respectively, initially present in the oxidized or nitridized surface layer (3).