摘要:
An assembly (220) includes a MEMS die (222) and an integrated circuit (IC) die (224) attached to a substrate (226). The MEMS die (222) includes a MEMS device (237) formed on a substrate (242). A packaging process (264) entails forming the MEMS device (237) on the substrate (242) and removing a material portion of the substrate (237) surrounding the device (237) to form a cantilevered substrate platform (246) suspended above the substrate (226) at which the MEMS device (237) resides. The MEMS die (222) is electrically interconnected with the IC die (224). A plug element (314) can be positioned overlying the platform (246). Molding compound (32) is applied to encapsulate the die (222), the IC die (224), and substrate (226). Following encapsulation, the plug element (314) can be removed, and a cap (236) can be coupled to the substrate (242) overlying an active region (244) of the MEMS device (237).
摘要:
An assembly (220) includes a MEMS die (222) and an integrated circuit (IC) die (224) attached to a substrate (226). The MEMS die (222) includes a MEMS device (237) formed on a substrate (242). A packaging process (264) entails forming the MEMS device (237) on the substrate (242) and removing a material portion of the substrate (237) surrounding the device (237) to form a cantilevered substrate platform (246) suspended above the substrate (226) at which the MEMS device (237) resides. The MEMS die (222) is electrically interconnected with the IC die (224). A plug element (314) can be positioned overlying the platform (246). Molding compound (32) is applied to encapsulate the die (222), the IC die (224), and substrate (226). Following encapsulation, the plug element (314) can be removed, and a cap (236) can be coupled to the substrate (242) overlying an active region (244) of the MEMS device (237).
摘要:
A MEMS device (20) includes a movable element (20) suspended above a substrate (22) by a spring member (34) having a spring constant (104). A spring softening voltage (58) is applied to electrodes (24, 26) facing the movable element (20) during a powered mode (100) to decrease the stiffness of the spring member (34) and thereby increase the sensitivity of the movable element (32) to an input stimulus (46). Upon detection of a stiction condition (112), the spring softening voltage (58) is effectively removed to enable recovery of the movable element (32) from the stiction condition (112). A higher mechanical spring constant (104) yields a stiffer spring (34) having a larger restoring force (122) in the unpowered mode (96) in order to enable recovery from the stiction condition (112). A feedback voltage (56) can be applied to feedback electrodes (28, 30) facing the movable element (32) to provide electrical damping.
摘要:
A MEMS sensor (20, 86) includes a support structure (26) suspended above a surface (28) of a substrate (24) and connected to the substrate (24) via spring elements (30, 32, 34). A proof mass (36) is suspended above the substrate (24) and is connected to the support structure (26) via torsional elements (38). Electrodes (42, 44), spaced apart from the proof mass (36), are connected to the support structure (26) and are suspended above the substrate (24). Suspension of the electrodes (42, 44) and proof mass (36) above the surface (28) of the substrate (24) via the support structure (26) substantially physically isolates the elements from deformation of the underlying substrate (24). Additionally, connection via the spring elements (30, 32, 34) result in the MEMS sensor (22, 86) being less susceptible to movement of the support structure (26) due to this deformation.
摘要:
A MEMS device (20) includes a proof mass (32) coupled to and surrounding an immovable structure (30). The immovable structure (30) includes fixed fingers (36, 38) extending outwardly from a body (34) of the structure (30). The proof mass (32) includes movable fingers (60), each of which is disposed between a pair (62) of the fixed fingers (36, 38). A central area (42) of the body (34) is coupled to an underlying substrate (24), with the remainder of the immovable structure (30) and the proof mass (32) being suspended above the substrate (24) to largely isolate the MEMS device (20) from package stress, Additionally, the MEMS device (20) includes isolation trenches (80) and interconnects (46, 50, 64) so that the fixed fingers (36), the fixed fingers (38), and the movable fingers (60) are electrically isolated from one another to yield a differential device configuration.
摘要:
An inertial sensor (20) includes a drive mass (30) configured to undergo oscillatory motion and a sense mass (32) linked to the drive mass (30). On-axis torsion springs (58) are coupled to the sense mass (32), the on-axis torsion springs (58) being co-located with an axis of rotation (22). The inertial sensor (20) further includes an off-axis spring system (60). The off-axis spring system (60) includes off-axis springs (68, 70, 72, 74), each having a connection interface (76) coupled to the sense mass (32) at a location on the sense mass (32) that is displaced away from the axis of rotation (22). Together, the on-axis torsion springs (58) and the off-axis spring system (60) enable the sense mass (32) to oscillate out of plane about the axis of rotation (22) at a sense frequency that substantially matches a drive frequency of the drive mass (30).
摘要:
A microelectromechanical systems (MEMS) transducer (90) is adapted to sense acceleration in mutually orthogonal directions (92, 94, 96). The MEMS transducer (90) includes a proof mass (100) suspended above a substrate (98) by an anchor system (116). The anchor system (116) pivotally couples the proof mass (100) to the substrate (98) at a rotational axis (132) to enable the proof mass (100) to rotate about the rotational axis (132) in response to acceleration in a direction (96). The proof mass (100) has an opening (112) extending through it. Another proof mass (148) resides in the opening (112), and another anchor system (152) suspends the proof mass (148) above the surface (104) of the substrate (98). The anchor system (152) enables the proof mass (148) to move substantially parallel to the surface (104) of the substrate (98) in response to acceleration in at least another direction (92, 94).
摘要:
A MEMS device that has a sensitivity to a stimulus in at least one sensing direction includes a substrate, a movable mass with corner portions suspended in proximity to the substrate, at least one suspension structure coupled approximately to the corner portions of the movable mass for performing a mechanical spring function, and at least one anchor for coupling the substrate to the at least one suspension structure. The at least one anchor is positioned approximately on a center line in the at least one sensing direction.
摘要:
A microelectromechanical systems (MEMS) capacitive sensor (52) includes a movable element (56) pivotable about a rotational axis (68) offset between ends (80, 84) thereof. A static conductive layer (58) is spaced away from the movable element (56) and includes electrode elements (62, 64). The movable element (56) includes a section (74) between the rotational axis (68) and one end (80) that exhibits a length (78). The movable element (56) further includes a section (76) between the rotational axis (68) and the other end (84) that exhibits a length (82) that is less than the length (78) of the section (74). The section (74) includes slots (88) extending through movable element (56) from the end (80) toward the rotational axis (68). The slots (88) provide stress relief in section (74) that compensates for package stress to improve sensor performance.
摘要:
A circuit and method for correcting a sense signal of a sensor (100) where the sense signal is reduced by a negative nonlinear error component introduced by membrane stress in a sensor structure (101). A first transducer (103) is disposed at a location (203) having substantial bending stress to produce a sense signal having a linear component and the nonlinear error component. A second transducer (102) is disposed at a location (202) with substantially zero bending stress to produce a sense signal having the nonlinear error component but a substantially zero linear component. The sense signal from the second transducer (102) is added to the sense signal from the first transducer (103) to correct the nonlinear error for producing a linear output sense signal (VOUT) of the sensor (100) which is representative of the physical condition.