Contact structure for gallium arsenide and manufacture thereof

PURPOSE: To obtain a contact structure for gallium arsenide by forming continuous layers of Ni, Au, Ge and Ni on an n-type GaAs substrate and then forming a metal oxide tungsten layer, a fifth layer, and then rapidly thermally annealing the structure. CONSTITUTION: A contact structure for an impurity region 20, which is a doner- doped part of a gallium arsenide substrate 10, is made by depositing five layers on the substrate 10. A first layer is a nickel layer 32, a second a gold layer 34, a third a gallium layer 36, a fourth a nickel layer 38, and a fifth a metal oxide tungsten layer 40. After depositing the five layers separately, the contact structure is thermal-annealed. Thus manufactured contact layer is formed of an intermetallic NiGe compound, including an AuGa compound, coated with a metal oxide tungsten film. Due to this structure, the contact structure can be brought into contact with the n-type GaAs substrate so that the advantage of the n-type GaAs substrate can be made full use of.