Micromachined force-balance feedback accelerometer with optical displacement detection
| DWPI Title: Method for fabricating micro-machined accelerometer in e.g. navigation system, involves removing portion of buried oxide layer through device-side trenches and back-side trenches to allow upward and downward movement of proof mass |
| Abstract: An accelerometer includes a proof mass and a frame that are formed in a handle layer of a silicon-on-an-insulator (SOI). The proof mass is separated from the frame by a back-side trench that defines a boundary of the proof mass. The accelerometer also includes a reflector coupled to a top surface of the proof mass. An optical detector is located above the reflector at the device side. The accelerometer further includes at least one suspension spring. The suspension spring has a handle anchor that extends downwards from the device side to the handle layer to mechanically support upward and downward movement of the proof mass relative to a top surface of the proof mass. |
| Use: Method for fabricating a micro-machined accelerometer in small-size light-weight handheld device such as navigation system, robotic and physics experiment. |
| Advantage: The method enables operating the accelerometer in number of modes such as force-balance feedback, optical lock-in, distance lock-in and open loop modes so as to satisfy a particular application and operating environment. The method enables providing number of device-side and back-side trenches that are built into the handle layer and a device layer of the accelerometer die so as to allow the accelerometer to be fabricated with a simple and efficient process. |
| Novelty: The method involves forming a first device side trenches extending from a device side of a silicon-on-an-insulator (SOI) through a buried oxide layer (610). The first trenches are filled (620) with materials. Second device side trenches are extended (630) from the device side to reach the layer. A back-side trench extending from a bottom surface of a handle layer to reach the layer is formed (660). A portion of the layer is removed (670) through the second trenches and the back-side trenches to allow upward and downward movement of the proof mass relative to a top surface of the proof mass. |
| Filed: 12/13/2011 |
| Application Number: US13324012A |
| Tech ID: SD 11413.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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