# US 2017/0283252 A1 · Microfabricated pressure transducer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0283252 A1 - Document ID: US20170283252A1 - Status: Published application - Kind: A1 - Application number: 15/477,593 - Filed: 2017-04-03 - Published: 2017-10-05 - Earliest claimed: 2016-04-04 - Assignees: Innovative Micro Technology - Applicants: Innovative Micro Technology - Inventors: Benedikt ZEYEN - Web page: https://patentgrep.com/patent/US20170283252A1 ## CPC - B81C 1/00182: {Arrangements of deformable or non-deformable structures, e.g. membrane and cavity for use in a transducer} - B81B 3/0018: {Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators} - G01L 7/022: {constructional details, e.g. mounting of elastically-deformable gauges (G01L7/041, G01L7/061, G01L7/082, G01L7/102, G01L7/163, G01L7/182 take precedence)} - G01L 7/024: {with mechanical transmitting or indicating means (G01L7/043, G01L7/063, G01L7/084, G01L7/104, G01L7/166, G01L7/185 take precedence)} - G01L 7/026: {with optical transmitting or indicating means (G01L7/045, G01L7/065, G01L7/086, G01L7/106, G01L7/187 take precedence)} - G01L 7/163: {construction or mounting of pistons} - G01L 9/0001: {Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means (G01L9/0026, G01L9/0033, G01L9/0082, G01L9/0089, G01L9/0091 take precedence)} - G01L 9/0042: {Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms (details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively)} - G01L 9/0054: {integral with a semiconducting diaphragm} - G01L 9/0089: {Transmitting or indicating the displacement of pistons by electrical, electromechanical, magnetic or electromagnetic means (G01L9/0008 takes precedence)} - B81B 2201/0264: Pressure sensors - B81C 2201/01: in or on a substrate - B81C: PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS (making microcapsules or microballoons B01J13/02; processes or apparatus specially adapted for the manufacture or treatment of piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/01) - B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00) - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) ## Abstract A microfabricated pressure transducer is formed in a multilayer substrate by etching a plurality of shallow and deep wells into the layers, and then joining these wells with voids formed by anisotropic etching. The voids define a flexible membrane over the substrate which deforms when a force is applied. ## Claims ### Claim 1 A microfabricated pressure transducer, comprising: a substrate of one or more materials with two embedded etch stop layers defining a top, center and bottom substrate part, the top substrate part having a number of shallow wells extending through the top substrate part, and defining a perforated membrane in the top substrate part which is suspended over a void; the top and center substrate parts also having a plurality of deep wells, the deep wells being deeper than the shallow wells and extending through the top and center substrate parts, and defining a smaller unperforated membrane on the bottom substrate, wherein the perforated and unperforated membranes form a force-to-pressure transducer. ### Claim 2 (depends on 1) The microfabricated pressure transducer of claim 1, wherein the shallow wells are passivated on the sidewalls which breached the top etch stop; and wherein the deep wells are passivated on the sidewalls only in the region of the top substrate. ### Claim 3 (depends on 1) The microfabricated pressure transducer of claim 1, wherein the void connects the shallow and the deeper wells with each other in the center substrate parts. ### Claim 4 (depends on 1) The microfabricated pressure transducer of claim 1, wherein the deep wells are connected on the center substrate part. ### Claim 5 (depends on 4) The microfabricated pressure transducer of claim 4, wherein the shallow wells define the larger perforated membrane on the top substrate. ### Claim 6 (depends on 4) The microfabricated pressure transducer of claim 4, wherein the deeper wells define the smaller unperforated membrane on the bottom substrate. ### Claim 7 (depends on 1) The microfabricated pressure transducer of claim 1, wherein the perforated membrane is connected to the bottom substrate part by a piston structure in the center substrate part, thereby forming the force-to-pressure transducer. ### Claim 8 (depends on 1) The microfabricated pressure transducer of claim 1, wherein the substrate parts are comprised of at least one of silicon, glass, polymers, metals, and combinations thereof. ### Claim 9 (depends on 1) The microfabricated pressure transducer of claim 1, wherein the embedded etch stop layers are comprised of at least one of a thermal oxide or a metal. ### Claim 10 (depends on 1) The microfabricated pressure transducer of claim 1, wherein the sidewalls on the etch stop layers are comprised of at least one of a thermal oxide and a CxFy polymer, wherein x and y are two different integers. ### Claim 11 (depends on 1) The microfabricated pressure transducer of claim 1, wherein the wells are formed by an isotropic etchant and are spaced radially around a center point, with the shallower wells located at a larger radius than the deeper wells. ### Claim 12 (depends on 11) The microfabricated pressure transducer of claim 11, wherein the isotropic etchant comprises at least one of XeF2 gas, KOH, SF6 plasma, HF, and oxygen plasma, and wherein the perforated membrane includes about 4 shallower wells and about 10 to about 15 deeper wells. ### Claim 13 A method for forming a microfabricated pressure transducer, comprising: providing a multilayer substrate having a top, center and bottom layer, wherein the layers are separated by top and bottom etch stop layers; forming a plurality of holes through the top layer and top etch stop layer; and forming a void below the top layer and top etch stop layer and above the bottom layer and bottom etch stop layer, but leaving at least one structure connecting the top and the bottom layers to form the pressure transducer. ### Claim 14 (depends on 13) The method of claim 13, wherein the holes comprise a plurality of shallow wells formed through the top layer. ### Claim 15 (depends on 14) The method of claim 14, further comprising: passivating at least the top substrate to form sidewall etch stops without passivating an interface to the second layer; continuing to etch a subset of the shallow wells anisotropically through most or all of the center substrate to form deep wells; etching the center layer isotropically down and outward from the wells to create a membrane on the top layer and a membrane on the bottom layer; stopping the isotropic etch so that the etch front from the shallow wells does not contact the bottom membrane thus making the top membrane larger than the bottom membrane; arranging the wells so that some of them are spaced sufficiently to surround one or several future piston; and stopping the isotropic etch so that the etch fronts from the sufficiently spaced wells do not meet and thus forms a piston-like connection between the top membrane and bottom membrane. ### Claim 16 (depends on 15) The method of claim 15, further comprising etching the center layer to form a void that connects the shallow and the deeper wells with each other on the top part and the center substrate parts. ### Claim 17 (depends on 15) The method of claim 15, wherein the deep wells are connected on the center substrate part. ### Claim 18 (depends on 15) The method of claim 15, wherein the shallow wells define the larger perforated membrane on the top substrate. ### Claim 19 (depends on 15) The method of claim 15, wherein the deeper wells define the smaller unperforated membrane on the bottom substrate. ### Claim 20 (depends on 15) The method of claim 15, wherein the three layer substrate comprises silicon, glass, polymers, metals and a combination thereof, wherein the etch stops comprise at least one of a thermal Oxide or a CxFy polymer, and wherein the isotropic etch uses at least one of XeF2 gas, KOH, SF6 plasma, HF, and oxygen plasma.