| 摘要 |
PURPOSE:To suppress semiconductor constituent components to be precipitated on the surface of the lower electrode metal layer from being diffused in the upper electrode metal layer by a method wherein the lower metal layer for the bonding electrode is once cooled after being coated and the upper metal layer for the bonding electrode is evaporated on the lower metal layer. CONSTITUTION:An AuBe alloy layer 4 and an AuGe alloy layer 5 are respectively vacuum-evaporated on the back surface of a P-type GaAs substrate 1 and on the surface of an N-type GaAlAs layer 3. A heat treatment is performed in N2 gas, whereby an ohmic contact is given to the alloy layers 4 and 5 to form ohmic electrodes. An Au layer 6 is evaporated on the alloy layer 5 at a temperature of about 150 deg.C. After the Au layer 6 is cooled to a temperature of about 120 deg.C, an evaporation of an Au layer is again started and a second Au layer 7 is coated on the Au layer 6. The wafer is taken out outside, a patterning is performed on the Au layers 6 and 7 and the bonding electrode is formed. By this way, Ga, Ge and so forth, which are precipitated on the surface of the Au layer 6, are suppressed from being diffused in the Au layer 7. |
