| 摘要 |
PROBLEM TO BE SOLVED: To provide a process for forming the silicon germanium base of a heterojunction transistor. SOLUTION: First, a silicon substrate a having a mesa encircled in a trench is formed. Then a silicon geranium layer is adhered to the substrate, the part of the germanium layer which is abutted on the mesa is removed and a silicon germanium base is formed. The process of a second embodiment comprises a step that the silicon substrate having the mesa encircled in the trench is formed, a step that a dielectric layer is formed in the trench abutted on the mesa, and a step that the silicon germanium layer is grown on the upper surface of the mesa by a selectively epitaxial growth method to form a silicon germanium base.
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