Method of manufacturing an accelerometer
3 Assignments
0 Petitions
Accused Products
Abstract
Devices fabricated on a wafer are encapsulated by forming a pattern of bond rings on a cap wafer and aligning and bonding the two wafers together, under thermo-compression, so that an operational part (22) of each device (20) is surrounded by a respective bond ring (21). The bond ring provides a hermetic seal by occupying any trenches (25) or other discontinuities, such as conductive tracks (23), in the upper surface of the device crossed by the ring. An accelerometer is manufactured by etching at least one cavity (5) into the top side of a substrate (1), bonding an intermediate layer of material (6) onto the top side of the substrate, depositing metallization (7) onto the intermediate layer and etching the metallization and intermediate layer to form a sensor structure suspended over each cavity. Conductive tracks (31, 32) of a lower metallization layer deposited on the substrate (30) cross under tracks (37, 38) deposited on the upper side of the intermediate layer (35, 36) without making electrical connection. Bridges are fabricated by forming cavities (33, 34) on the underside of the intermediate layer to accommodate the lower track.
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Citations
130 Claims
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1-59. -59. (canceled)
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60. A method of bonding a cap wafer (34) to a device wafer, the device wafer having a substrate (30), a pattern of individual devices fabricated on one face of the substrate, and at least one trench (33) in the one face of the substrate the method including the following steps performed in the order recited:
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(a) forming glass bond rings (35) on one face of the cap wafer (12-2), the bond rings being dimensioned and arranged on the cap wafer for respectively surrounding the individual devices on the device wafer when the cap wafer is aligned with the device wafer;
(b) aligning and placing the cap wafer on the device wafer (12-3) with said one face of the cap wafer adjacent the one face of the substrate on which is formed the pattern of individual devices, the two wafers being aligned with the bond rings respectively surrounding the individual devices;
(c) exposing the aligned wafers to a vacuum (12-4), and increasing the temperature (12-6) of the wafers to a predetermined bonding temperature. (d) applying a biasing force (12-7) to urge the aligned wafers together and to compress the bond rings;
(e) reducing the temperature (12-8) of the wafers to room temperature and removing the force when the temperature of the wafers is less than a first predetermined temperature;
(f) venting the vacuum to atmosphere (12-9) when the temperature of the wafers is less than a second predetermined temperature; and
wherein a full width portion of each trench of a device is crossed by, and substantially occupied by, a portion of the respective bond ring (35). - View Dependent Claims (61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90)
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- 91. A sealed device, the device being formed on a portion of a device wafer, the device wafer portion having a substrate that includes at least one trench (30), the device being fabricated on one face of the substrate, including the at least one trench, the portion of the device wafer being capped by a portion of a cap wafer (34), the cap wafer portion being bonded to the device wafer portion by a ring bond (35), the ring bond hermetically sealing the device and occupying a portion of the at least one trench.
- 95. A sealed device, the device being fabricated from one or more layers formed on one face of a substrate (30) that includes at least one trench, the device having a cap (34) which is bonded to the outermost surface of said layers by a bond ring (21, 35), the bond ring surrounding and hermetically sealing at least an operational portion (22) of the device and occupying a portion of the at least one trench.
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110. A sealed device as claimed in claim 110, wherein the device is an accelerometer.
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112. A method of fabricating an accelerometer including the steps of:
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etching at least one cavity (5) into the top side of a substrate (1) of insulating material, bonding a top layer (6) of material onto the top side of the substrate, depositing metallization (7) onto the layer of material, and etching the top layer of material to form a sensor structure suspended over each cavity. - View Dependent Claims (113, 114, 115, 116, 117, 118, 119, 120, 122, 130)
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123. An accelerometer including:
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a bottom substrate layer (1) of insulating material, a top layer (6) bonded to the bottom layer, at least one cavity (5) in the bottom substrate layer formed before the top layer is bonded to the bottom layer, a capacitive sensor structure formed in the top layer and suspended over the cavity, and at least one point (10) suitable for electrical connection in contact with each part of the capacitive sensor structure formed before the capacitive sensor structure is formed. - View Dependent Claims (124)
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126. A method of manufacturing a wafer fabricated device including the steps of:
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(o) depositing a first metallization onto one side of a substrate of insulating material (30), (p) selectively etching the deposited first metallization to provide a pattern including at least one conductive track (31, 32), (q) selectively etching at least one cavity (33, 34) in a first face of a semi-conducting wafer (35, 36), (r) bonding the etched first face of the wafer to the one side of the substrate, so that the at least one cavity overlies the at least one conductive track, (s) selectively etching the wafer to electrically isolate conductive runners on the wafer (35, 36). - View Dependent Claims (127, 128, 129)
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Specification