Wafer process flow for a high performance MEMS accelerometer
First Claim
1. A process for fabricating a pendulous accelerometer having a sensing plate with a symmetric plate area and an asymmetric plate mass, the process comprising the steps of:
- providing a first substrate having a top planar surface, a bottom planar surface substantially parallel to the top planar surface, and a total thickness extending from the top planar surface to the bottom planar surface;
etching a portion of the first substrate to a first predetermined depth from the top planar surface to form a plurality of first protrusions each having a top planar surface;
providing a second substrate having an upper planar surface;
etching a portion of the second substrate to a second predetermined depth extending from the upper planar surface to form a plurality of second protrusions each having an upper planar surface;
bonding the top planar surface of at least one of the first protrusions to the upper planar surface of at least one of the second protrusions to form an anchor portion; and
etching a portion of the first substrate from the bottom planar surface to a third predetermined depth at least equal to the difference between the total thickness of the first substrate and the first predetermined depth to form a freely rotatable sensing plate having a solid proof mass on a first side of the anchor portion and a substantially hollow proof mass on a second side of the anchor portion.
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Accused Products
Abstract
A process for fabricating a pendulous accelerometer, including the steps of: providing a first substrate having a top planar surface, etching a portion of the first substrate to a first predetermined depth from the top planar surface to form a plurality of first protrusions, providing a second substrate, etching a portion of the second substrate to a second predetermined depth to form a plurality of second protrusions, bonding planar surfaces of the first protrusions to planar surfaces of the second protrusions, and etching a portion of the first substrate from an opposite side of the first substrate to a third predetermined depth equal to or greater than the difference between the total thickness of the first substrate and the first predetermined depth to form a freely rotatable sensing plate that includes a substantially hollow proof mass.
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Citations
20 Claims
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1. A process for fabricating a pendulous accelerometer having a sensing plate with a symmetric plate area and an asymmetric plate mass, the process comprising the steps of:
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providing a first substrate having a top planar surface, a bottom planar surface substantially parallel to the top planar surface, and a total thickness extending from the top planar surface to the bottom planar surface; etching a portion of the first substrate to a first predetermined depth from the top planar surface to form a plurality of first protrusions each having a top planar surface; providing a second substrate having an upper planar surface; etching a portion of the second substrate to a second predetermined depth extending from the upper planar surface to form a plurality of second protrusions each having an upper planar surface; bonding the top planar surface of at least one of the first protrusions to the upper planar surface of at least one of the second protrusions to form an anchor portion; and etching a portion of the first substrate from the bottom planar surface to a third predetermined depth at least equal to the difference between the total thickness of the first substrate and the first predetermined depth to form a freely rotatable sensing plate having a solid proof mass on a first side of the anchor portion and a substantially hollow proof mass on a second side of the anchor portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A process for fabricating a pendulous accelerometer having an asymmetrical sensing plate, the process comprising the steps of:
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depositing a first masking material on a portion of a top planar surface of a first substrate, the first substrate having a bottom planar surface substantially parallel to the top planar surface and a total thickness measured from the top planar surface to the bottom planar surface; etching a remaining portion of the first substrate that is not covered by the masking material to a first predetermined depth measured from the top planar surface to form a plurality of first protrusions having planar surfaces; depositing a second masking material on a portion of a first planar surface of a second substrate; etching a remaining portion of the second substrate that is not covered by the masking material to a second predetermined depth measured from the first planar surface to form a plurality of second protrusions each having a planar surface; bonding the planar surface of at least one of the first protrusions to the planar surface of at least one of the second protrusions to form an anchor portion; etching the first substrate from the bottom planar surface to a third predetermined depth at least equal to the difference between the total thickness of the first substrate and the first predetermined depth to form a freely rotatable sensing plate having a solid proof mass on a first side of the anchor portion and a substantially hollow proof mass on the second side of the anchor portion. - View Dependent Claims (20)
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Specification