32 results about "Piezoresistive accelerometer" patented technology

The invention discloses an MEMS piezoresistive accelerometer. The MEMS piezoresistive accelerometer comprises a substrate, a frame, elastic beams, a main mass block, secondary mass blocks, an upper sealing cap and a plurality of sets of piezoresistors, wherein the main mass block is arranged in the center of the frame through the elastic beams in a supporting suspension mode, the frame is fixed to the upper end of the substrate, the secondary mass blocks are arranged on the elastic beams respectively, a specially-shaped elastic beam structure is formed by the secondary mass blocks and the elastic beams, the piezoresistors are arranged in the middle of the elastic beams and the positions of connection between the elastic beams and the frame respectively, the main mass block and the elastic beams are the same in thickness, the upper sealing cap is fixed to the upper end face of the frame, a groove structure is arranged inside the upper sealing cup, and the main mass block is arranged inside a groove in a suspended mode, and can freely move when sensing inertia force in all the directions. According to the MEMS piezoresistive accelerometer, due to the facts that the structure that the elastic beams and the single main mass block are arranged is adopted, and changes of stress, at different positions, of the specially-shaped elastic beams are reflected when the main mass block senses the inertia force in different directions, the size of a device is effectively reduced, and the MEMS piezoresistive accelerometer has the advantages of being high in sensitivity and natural frequency, good in high-overload resistant capacity and the like.

The invention discloses a method of making a self-aligned MEMS piezoresistive accelerometer, comprising the following steps: making a cavity at the bottom of a silicon substrate through a KOH etching process; growing an oxide layer and a silicon nitride layer on the top of the silicon substrate in sequence from bottom to top; making a piezoresistive pattern and a structure release pattern on the silicon nitride layer at the same time through a lithography process, and etching the silicon nitride layer at the piezoresistive pattern and at the structure release pattern; etching the oxide layer at the piezoresistive pattern, and forming a piezoresistor through an injecting process and an annealing process; etching the oxide layer at the structure release pattern to form a structure release area; deeply etching the silicon substrate in the structure release area to form a movable structure, thus getting an MEMS piezoresistive accelerometer. The piezoresistive pattern and the structure release pattern are formed in the same lithography process. There is no need for equipment to carry out alignment in the machining process. Self-alignment of the piezoresistor and a device structure is realized. Thus, the symmetry of devices is improved, error caused by position deviation of the piezoresistor is reduced, and the performance of devices is improved.

Disclosed is a piezoresistive acceleration sensor having a full-bridge microbeam structure, comprising a frame (1), a cantilever beam (2), microbeams (3) and a mass block (4). The cantilever beam (2) is on the axis of symmetry of the mass block (4), the microbeams (3) are four in number, and are axisymmetrically distributed on an edge of the mass block (4) using the axis on which the cantilever beam (2) is located, and piezoresistive sensing resistors are provided on the four microbeams, the four piezoresistive sensing resistors constituting a Wheatstone full bridge circuit. Amplifying the strain of the cantilever beam increases the sensitivity; the four piezoresistive sensing resistors are all within a chip, and because the effects of resistance drift on the circuit caused by measuring changes in the ambient temperature cancel each other out in a full bridge circuit, the temperature stability is increased; and the four microbeams increase the restriction on the vibration of the mass block, raising the first order resonance frequency.