Capacitive microaccelerometers and fabrication methods
First Claim
1. Sensing apparatus comprising:
- a substrate comprising a lower section and an upper section, the upper section comprising a plurality of tethers formed between selected lateral edges and a central region of the upper section, and a plurality of electrodes disposed along selected edges of the upper section;
a seismic mass comprising the central region of the upper section and a portion of the lower section disposed beneath the central region; and
conductive material disposed along edges of gaps in the upper section defining the seismic mass that reduce respective sizes of the gaps.
2 Assignments
0 Petitions
Accused Products
Abstract
Disclosed are moveable microstructures comprising in-plane capacitive microaccelerometers, with submicro-gravity resolution (<200 ng/√Hz) and very high sensitivity (>17 pF/g). The microstructures are fabricated in thick (>100 μm) silicon-on-insulator (SOI) substrates or silicon substrates using a two-mask fully-dry release process that provides large seismic mass (>10 milli-g), reduced capacitive gaps, and reduced in-plane stiffness. Fabricated devices may be interfaced to a high resolution switched-capacitor CMOS IC that eliminates the need for area-consuming reference capacitors. The measured sensitivity is 83 mV/mg (17 pF/g) and the output noise floor is −91 dBm/Hz at 10 Hz (corresponding to an acceleration resolution of 170 ng/√Hz). The IC consumes 6 mW power and measures 0.65 mm2 core area.
-
Citations
12 Claims
-
1. Sensing apparatus comprising:
-
a substrate comprising a lower section and an upper section, the upper section comprising a plurality of tethers formed between selected lateral edges and a central region of the upper section, and a plurality of electrodes disposed along selected edges of the upper section; a seismic mass comprising the central region of the upper section and a portion of the lower section disposed beneath the central region; and conductive material disposed along edges of gaps in the upper section defining the seismic mass that reduce respective sizes of the gaps. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. Sensing apparatus comprising:
-
a silicon-on-insulator substrate comprising a lower silicon handle layer and an upper silicon device layer separated by an insulating layer, which device layer comprises a plurality of tethers formed between selected lateral edges and a central region of the device layer, and a plurality of parallel plate electrodes disposed along selected edges of the device layer; a seismic mass comprising a central region of the device layer, a portion of the insulating layer disposed beneath the central region of the device layer, and a portion of the handle layer disposed beneath the portion of the insulating layer; and doped polysilicon disposed along edges of gaps in the device layer defining the seismic mass which reduce respective sizes of the gaps.
-
Specification