Methods of making composite conductive structures in integrated circuits

A method of forming a composite structure comprising

• providing a substrate of semiconductor material having an overlying layer of insulating material,
• forming a conductor of a refractory metal which is substantially nonreactive with silicon dioxide in a desired pattern overlying said layer of insulating material,
• forming over said conductor of metallic material and said layer of insulating material a layer of polycrystalline silicon,
• heating said substrate including said conductor of metallic material and said overlying layer of polycrystalline silicon to a temperature and for a time to cause said layer of polycrystalline silicon to react with a portion of said conductor to form a layer of a silicide of said metallic material overlying a remaining portion of said conductor unconverted to a silicide thereof,
• removing the portion of said layer of polycrystalline silicon which has not reacted with said metallic material,
• heating said substrate including said conductor and said layer of said metal silicide in an oxidizing atmosphere at a temperature and for a time to cause said oxidizing atmosphere to react with said layer of said silicide to convert a portion thereof to silicon dioxide overlying another portion of said layer of said silicide unconverted to silicon dioxide.