Silicon accelerometer fabrication method
First Claim
1. A process for fabricating a silicon accelerometer comprising the steps of:
- providing a low donor concentration silicon substrate,forming a high donor concentration silicon layer in a predetermined region on the surface of the substrate by diffusion or ion implantation,forming a low donor concentration silicon layer over the surface of said substrate by vapor phase epitaxy,forming at least one opening in said low donor concentration layer thereby exposing edges of said high donor concentration layer,after said forming at least one opening, converting said high donor concentration layer into porous silicon by anodization, said converting of said high donor concentration layer being bounded by said exposed edges of said high donor concentration layer,mounting a mass onto the low donor concentration layer,removing the porous silicon by etching between the substrate and the low donor concentration layer to form a cavity between the substrate and the low donor concentration layer, said etching resulting in a complete removal of the porous silicon.
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Abstract
A silicon accelerometer comprising a substrate, one or more pairs of beams, a pedestal, a mass on top of the pedestal and a cavity beneath the pedestal all of which is formed by a single-sided processing method. The pedestal is suspended over the cavity by the beams which provides the only support for the pedestal. The beams are supported by the substrate. The main steps of fabricating this structure comprise diffusion or ion implantation and epitaxial growth to form a buried high donor concentration layer on the surface of the substrate, chemical vapor deposition and photoetching to expose a portion of the edge of the buried layer to the ambiente, anodization to convert the high donor concentration layer into porous silicon and selectively etching to remove the porous silicon.
67 Citations
19 Claims
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1. A process for fabricating a silicon accelerometer comprising the steps of:
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providing a low donor concentration silicon substrate, forming a high donor concentration silicon layer in a predetermined region on the surface of the substrate by diffusion or ion implantation, forming a low donor concentration silicon layer over the surface of said substrate by vapor phase epitaxy, forming at least one opening in said low donor concentration layer thereby exposing edges of said high donor concentration layer, after said forming at least one opening, converting said high donor concentration layer into porous silicon by anodization, said converting of said high donor concentration layer being bounded by said exposed edges of said high donor concentration layer, mounting a mass onto the low donor concentration layer, removing the porous silicon by etching between the substrate and the low donor concentration layer to form a cavity between the substrate and the low donor concentration layer, said etching resulting in a complete removal of the porous silicon. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification