| 摘要 |
A substrate defining a cavity comprising a wide, shallow first portion and a narrow, deep second portion is provided. The first portion of the cavity extends into the substrate from the front side of the substrate and is filled with sacrificial material. The second portion extends deeper into the substrate from the first portion. A device structure is fabricated over the sacrificial material. A release etchant is introduced from the back side of the substrate via the second portion of the cavity to remove from the first portion of the cavity the sacrificial material underlying the device structure. Removing from the first portion of the cavity the sacrificial material underlying the device structure by introducing the release etchant from the back side of the substrate via the second portion of the cavity allows the release etch to be performed without exposing the device structure to the release etchant. This allows the device structure to incorporate materials that have a low etch selectivity with respect to the sacrificial material.
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