Process for selectively forming refractory metal silicide layers on semiconductor devices

A method of forming and defining a refractory metal silicide layer on a substrate comprising,

• providing a blanket layer of SiO.sub.2 on said substrate,
• depositing a blanket layer of polycrystalline Si over said layer of SiO.sub.2,
• defining a pattern in said polycrystalline Si layer thereby exposing selected areas of said layer of SiO.sub.2,
• depositing a blanket layer of refractory metal silicide on said substrate over said layers of SiO.sub.2 and said polycrystalline Si,
• heating the composite substrate in an oxidizing environment to a temperature and for a time to thermally oxidize the metal silicide layer overlying said polycrystalline Si to form an upper layer of SiO.sub.2, and to convert the metal silicide layers overlying the SiO.sub.2 layer to a metal rich SiO.sub.2 layer,
• exposing the oxidized surface of said substrate to an etchant that selectively etches said metal rich silicon dioxide layer to thereby expose said blanket layer of SiO.sub.2.