| 摘要 |
PROBLEM TO BE SOLVED: To provide an HBT and its manufacturing method that can form stable undercut structure, in addition, can provide wider ledge structure to an emitter region that is formed on an unstable surface, and has excellent mass productivity and reliability. SOLUTION: By utilizing the selection etching characteristics of the GaAs and InGaAs of etching solution where hydrogen peroxide water is mixed with alkaline solution, and at the same time the pH of the mixed liquid is equal to 9.5 or more and 11.5 or less, an InGaAs layer is set to an overhang, and the undercut structure is formed in a shape where a GaAs layer is engraved. To this structure, a mask material is buried in the lower part of the overhang, and a region that is not covered with the mask material is etched by solution for etching the GaAs, thus forming the ledge structure. In addition, the undercut structure is utilized for forming emitter and base electrodes in self-alignment manner.
|
