Abstract:
A technique for manufacturing a piezoresistive sensing structure (170) includes a number of process steps. Initially, a piezoresistive element (108) is implanted into a first side of an assembly (102,106,104A) that includes a semiconductor material (102,104A). A passivation layer (110A) is then formed on the first side of the assembly (102,106,104A) over the element (108). The passivation layer (110A) is then removed from selected areas on the first side of the assembly (102,106,104A). A first mask is then provided on the passivation layer (110A) in a desired pattern. A beam (152), which includes the element (108), is then formed in the assembly over at least a portion of the assembly (102,106,104A) that is to provide a cavity (103). The passivation layer (110A) provides a second mask, in the formation of the beam (152), that determines a width of the formed beam (152).
Abstract:
The present invention involves an electrical verification method that detects moisture within the cavity of the semiconductor or micro-machined device. The method affects an increase in the time for sufficient water vapor to remain within an unsealed device, so that instability in the diode can be measurable over a longer period of time. The method begins with the step of forming at least one reservoir (30) on at least one of the device wafer (11) and the capping wafer (12). The at least one reservoir (30) connects to at least one diffusion channel (31), which is in communication with at least one reservoir port (32). The method further includes the steps of forming a PN junction diode (40) adjacent to the at least one reservoir port (32); bonding the device wafer (11) with the capping wafer (12) to form a cavity (16); and electrically testing the PN junction diode (40) as an indication of the presence of moisture within the cavity (16). The device assembly (10) of the present invention includes a capping wafer (12) bonded on a device wafer (11) to form a cavity (16); at least one reservoir (30) including at least one diffusion channel (31) for receiving a liquid and retaining moisture. The at least one diffusion channel communicates with at least one reservoir port (32), which is open into the cavity (16). An exposed PN junction diode (40) is provided adjacent to the at least one reservoir port (32), and a pair of metal pads (48,49) is connected to the exposed PN junction diode (40).
Abstract:
Impending rollover events are detected based on differential z-axis (i.e., vertical) acceleration. Vertical or z-axis acceleration measured at laterally opposite sides of the vehicle (10) are filtered (34, 36) and differenced (72/88/92), and the differential acceleration is processed and compared to a calibrated threshold (78/90/96) to detect impending rollover. Separate algorithms (38, 40, 42) are employed to detect different categories of rollover events, and a sum of the z-axis acceleration measurements is used as a safing signal (44, 50).
Abstract:
An infrared (IR) sensor (200) includes a semiconductor material (210), a circular membrane (204) and a thermopile (206A). The semiconductor material (210) includes a cavity (205) surrounded by a frame (212). The circular membrane (204) is positioned over the cavity (205) and has a perimeter supported by the frame (212). The membrane (204) has a first surface for receiving thermal radiation and an oppositely-disposed second surface. The membrane (204) includes at least one infrared absorbing layer (550). The thermopile (206A) includes a plurality of serially connected thermocouples. Each of the thermocouples has dissimilar electrically-resistive materials that define measurement junctions (209), which are positioned on the membrane (204), and reference junctions (207), which are positioned on the frame (212).
Abstract:
A process for making an acceleration sensitive impact detector involves steps of fabricating a semiconductive seismic mass layer; fabricating a seimconductive substrate having a recess in a surface thereof; fixing the seismic layer to the surface of the substrate so that the seismic mass layer covers the recess; etching a portion of the seismic mass layer overlying the recess to form a seismic mass that is supported over the recess by a beam; printing an electrically conductive circuit on the seismic mass and on the substrate, the printed circuits allowing an electrostatic force to be applied between the seismic mass and the substrate which is adapted to force the seismic mass away from the bottom of the recess formed in the substrate; and fixing a cap over the seismic mass to define a sealed cavity enclosing the seismic mass between the recess and the cap. The process provides an improved impact detector that is reliable and may be fabricated at a lower cost as compared with conventional processes and designs.
Abstract:
The present invention involves an electrical verification method that detects moisture within the cavity of the semiconductor or micro-machined device. The method affects an increase in the time for sufficient water vapor to remain within an unsealed device, so that instability in the diode can be measurable over a longer period of time. The method begins with the step of forming at least one reservoir (30) on at least one of the device wafer (11) and the capping wafer (12). The at least one reservoir (30) connects to at least one diffusion channel (31), which is in communication with at least one reservoir port (32). The method further includes the steps of forming a PN junction diode (40) adjacent to the at least one reservoir port (32); bonding the device wafer (11) with the capping wafer (12) to form a cavity (16); and electrically testing the PN junction diode (40) as an indication of the presence of moisture within the cavity (16). The device assembly (10) of the present invention includes a capping wafer (12) bonded on a device wafer (11) to form a cavity (16); at least one reservoir (30) including at least one diffusion channel (31) for receiving a liquid and retaining moisture. The at least one diffusion channel communicates with at least one reservoir port (32), which is open into the cavity (16). An exposed PN junction diode (40) is provided adjacent to the at least one reservoir port (32), and a pair of metal pads (48,49) is connected to the exposed PN junction diode (40).
Abstract:
A technique for manufacturing a piezoresistive sensing structure (170) includes a number of process steps. Initially, a piezoresistive element (108) is implanted into a first side of an assembly (102,106,104A) that includes a semiconductor material (102,104A). A passivation layer (110A) is then formed on the first side of the assembly (102,106,104A) over the element (108). The passivation layer (110A) is then removed from selected areas on the first side of the assembly (102,106,104A). A first mask is then provided on the passivation layer (110A) in a desired pattern. A beam (152), which includes the element (108), is then formed in the assembly over at least a portion of the assembly (102,106,104A) that is to provide a cavity (103). The passivation layer (110A) provides a second mask, in the formation of the beam (152), that determines a width of the formed beam (152).