US 11,906,375 B1Granted

Semiconductor strain gage and method of fabrication

AssigneePiezo-Metrics Inc

InventorsFranklin Curtis Wong, Robert Andrew Mueller, Kimberly Lakea Harrison, Farzad Khademolhosseini, Carolyn D. Bianco

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Abstract

The present disclosure is directed to methods for low-cost, high-volume production of strain gages having substantially uniform gage-to-gage resistances. Strain gages in accordance with the present disclosure are sculpted from a device layer of a semiconductor-on-insulator wafer using deep reactive ion etching, thereby enabling well-controlled electrical properties and physical dimensions of the strain gages. In some embodiments, groups of fully fabricated strain gages are physically connected to handling frames via sprues to facilitate handling, automated assembly, and/or tracing of individual gages from the beginning of fabrication through final packaging. In some embodiments, sprues are configured to mitigate accidental separation of the gages from their frames while simultaneously enabling their removal in response to specific forces applied by a handling tool.

Claims15

Dependent claims

A method for forming a first plurality of strain gages, the method comprising:

providing a semiconductor-on-insulator substrate comprising a device layer, a handle substrate, and a buried-oxide layer, wherein the device layer has a first thickness, and wherein the device layer comprises a first material having a first resistivity;
forming a first plurality of contact pairs, the contacts of each contact pair being electrically connected through the device layer;
determining a desired range for a gage resistance for the first plurality of strain gages;
providing a plurality of mask sets for defining a first plurality of bodies such that each body includes a different contact pair of the first plurality thereof, wherein each mask set of the plurality thereof includes a plurality of features for defining the first plurality of bodies, and wherein the features of each mask set of the plurality thereof have at least one lateral dimension that is different that the features of the other mask sets of the plurality thereof;
for each of the plurality of mask sets, generating a gage-resistance estimate for each strain gage of the first plurality thereof based at least in part on the at least one lateral dimension;
selecting a first mask set from the plurality of mask sets based on the plurality of gage-resistance estimates and the desired range for the gage resistance;
etching the device layer using the first mask set to define the first plurality of bodies;
and
releasing the first plurality of bodies from the handle substrate by removing at least a portion of the buried-oxide layer.

6 more elements

A method for forming a first plurality of strain gages, the method comprising:

providing a semiconductor-on-insulator substrate comprising a device layer, a handle substrate, and a buried-oxide layer, wherein the device layer has a first thickness, and wherein the device layer comprises a first material having a first resistivity;
forming a first plurality of contact pairs, the contacts of each contact pair being electrically connected through the device layer;
etching the device layer to form a first gage strip, wherein the first gage strip includes at least one body of a first plurality of bodies, a first frame, and a plurality of sprues, and wherein each body of the first plurality of bodies comprises a different contact pair of the first plurality thereof;
wherein the first frame is physically coupled with at least one body of the first plurality thereof by at least one sprue of the plurality of sprues;
and
releasing the first gage strip from the handle substrate by removing a portion of the buried-oxide layer.

3 more elements

A method for forming a first plurality of strain gages, the method comprising:

providing a semiconductor-on-insulator substrate comprising a device layer, a handle substrate, and a buried-oxide layer, wherein the device layer has a first thickness, and wherein the device layer comprises a first material having a first resistivity;
forming a first plurality of contact pairs, the contacts of each contact pair being electrically connected through the device layer;
etching the device layer to define a plurality of gage strips, wherein each gage strip includes at least one body of a first plurality of bodies, a frame of a plurality of frames, and a plurality of sprues, and wherein each body of the first plurality of bodies includes a different contact pair of the plurality thereof;
wherein each frame of the plurality thereof is physically coupled with each of its respective at least one body by at least one sprue of the plurality of sprues;
and
releasing the plurality of gage strips from the handle substrate by removing a portion of the buried-oxide layer.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/700,266Filed 21 Mar 2022 · us provisional application
Priority: 23 Mar 2021
Granted: 20 Feb 2024
Term ends: Not estimatedThe source records don’t support an estimate.

Classification3 codes

G01L 1/2293
Constructional details of the strain gauges: of the semi-conductor type
G01L 1/205
By measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids ; by making use of electrokinetic cells,…
G01L
Measuring force, stress, torque, work, mechanical power, mechanical efficiency, or fluid pressure

Family

Application63/164,923Us provisional application · filed 23 Mar 2021
US 11,906,375 B1This patent

From the US filing history. Foreign family members aren’t listed.

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