| 摘要 |
A SiGe monocrystalline etch-stop material system on a monocrystalline silico n substrate. The etch-stop material system can vary in exact composition, but is a doped or undoped Si1-xGex alloy with x generally between 0.2 and 0.5. The etch-stop of the invention includes the use of a graded-composition buffer between the silicon substrate and the uniform SiGe etch-stop mateial. Nominally, the buffer has a linearly-changing composition with respect to thickness, from pure silicon at the substrate/buffer interface to a composition of germanium, and dopant if also present, at the buffer/etch-sto p interface which can still be etched at an appreciable rate. Here, there is a strategic jump in germanium and concentration from the buffer side of the interface to the etch-stop material, such that the etch-stop layer is considerably more resistant to the etchant. The etch-stop is used for micromachining by aqueous anisotropic etchants of silicon such as potassium hydroxide, sodium hydroxide, litium hydroxide, ethylenediamine/pyrocatechol/pyrazine (EDP), TMAH, and hydrazine.
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