| 摘要 |
Creating cavities in an etchable material beneath a membrane comprises depositing a mask layer onto a substrate, forming two or more holes in the mask layer, etching the substrate by bringing it into contact with an etching liquid in the mask holes and optionally sealing the resulting cavities. A monocrystalline silicon substrate (1) is used, onto which a sacrificial etchable material layer is applied to cover part of the substrate surface or come to lie within the substrate beneath this surface. A cover layer (4) is applied onto the substrate surface layer and covers the sacrificial layer too. A pattern of small holes (2) is etched into the cover layer and then an etching liquid that can etch away the sacrificial layer without etching the cover layer is applied via the holes in order to remove the sacrificial layer. Anisotropic silicon is applied onto the substrate through the resulting holes up to fill the cavity as far down as a crystal plane (9) in the monocrystalline silicon. A layer can be deposited over the substrate surface to cover the holes. An accelerometer comprising a monocrystalline silicon wafer substrate, a weight supported by a membrane and an indicator for measuring elongation in the membrane, is also claimed. The weight layer comprises boron-doped monocrystalline silicon. The membrane comprises a layer deposited onto the silicon substrate after part of it has been doped with boron and holes in the membrane allow a cavity to be etched in the silicon substrate beneath the weight layer. A cover layer is deposited to seal the holes and cavity. The indicator is deposited onto the cover layer to extend between an outer region of the membrane and part of the cover layer lying outside the cavity. |
