Texas Instruments Incorporated Deutschland, Gmbh

Texas Instruments Corporation

Siegbert Hartauer

Steven Beringhause

Raymond E Mandeville

W Donald Rolph, Iii

Vaclav F Vilimek

A semiconductor device with a force and/or acceleration sensor (12), which has a spring-mass system (14, 16) responsive to the respective quantity to be measured and whose mass (16) bears via at least one resilient support element (14) on a semiconductor substrate (20). The semiconductor substrate (20) and the spring-mass system (14, 16) are integral components of a monocrystalline semiconductor crystal (10) with a IC-compatible structure. The three-dimensional structural form of the spring-mass system (12) is produced by anisotropic semiconductor etching, defined P/N junctions of the semiconductor layer arrangement functioning as etch stop means in order to more particularly create a gap (22) permitting respective movement of the mass (16) between the mass (16) and the semiconductor substrate (20).

Method of making a semiconductor device force and/or acceleration sensor

A semiconductor device comprises a piezoresistive pressure sensor (12), which has a membrane (14), which is constituted by a conducting epitaxy layer (16), which is applied to a conducting semiconductor substrate (18) of the opposite conductivity. On the outer surface (20) of the membrane facing away from the semiconductor substrate (18) at least one piezoresistor (22) is incorporated. Between the semiconductor substrate (18) and the epitaxy layer (16) an annularly structured intermediate layer (28) is incorporated, which defines a region (26'), adjoining the inner surface (24) of the membrane, of an opening (26) extending through the semiconductor substrate (18). This opening (26) is produced by anisotropic semiconductor etching, the intermediate layer (28) having a conductivity which is opposite to that of the semiconductor substrate so that this intermediate layer (28) functions as an etch stopping means and is not attacked by the etchant.

Method for making a piezoresistive pressure sensor of semiconductor

Semiconductor device with force and/or acceleration sensor

Semiconductor device with a piezoresistive pressure sensor

An accelerometer device comprises a silicon semiconductor member having a mass mounted on a support by integral beams extending between the mass and support to permit movement of the mass in response to acceleration. Piezoresistive sensors are accommodated in the beams for sensing strain in the beams during movement of the mass to provide an output signal from the device corresponding to the acceleration. The beams each have an end secured to the support and an end secured to the mass and taper intermediate the beam ends to provide a high and substantially uniform strain throughout the tapered section of the beam. The piezoresistive sensor is accommodated in the tapered beam section to be responsive to that high, uniform strain. Preferably the member has four beams mounting the mass, each beam has a tapered section extending from each end of the beam toward the center of the beam, and each beam section has a piezoresistive sensor accommodated therein to be responsive to the uniform strain within that beam section. The piezoresistive sensors are conveniently interconnected to compensate for off-axis acceleration in one direction by compensation within each leg of a bridge circuit and to compensate for off-axis acceleration in another direction by compensation within the full bridge circuit.

Accelerometer with improved strain gauge sensing means

Growing community of inventors

Landshut, Germany

Siegbert Hartauer