| 摘要 |
A graded SiGe sacrificial layer is epitaxially grown overlying a silicon substrate. A single crystal silicon layer is then grown by an epitaxial process overlying the graded SiGe layer. A SiGe layer is next grown by an epitaxial process as a single crystal layer overlying the silicon layer. A subsequent silicon layer, which becomes the active silicon layer for the transistors, is epitaxially grown overlying the second silicon germanium layer. Together the epitaxially grown Si, SiGe and Si layers form a laminate semiconductor structure. A MOS transistor is then formed on the active area of the single crystal silicon. The graded SiGe sacrificial layer is removed by an etch process to electrically isolate the laminate semiconductor structure from the substrate.
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