PRESSURE SENSOR

• US 20150122038A1
• Filed: 10/23/2014
• Published: 05/07/2015
• Est. Priority Date: 11/06/2013
• Status: Active Grant

• Current Assignee: InvenSense International, LLC
• Original Assignee: Sensirion AG (Sensirion Holding AG)
• Inventors: VON WALDKIRCH, Marc, BUHLER, Johannes, HUMMEL, Rene, LIN, Chung-Hsien, MAYER, Felix, BRAUN, Stephan, HERMERSDORF, Marion
• Granted Patent: US 10,161,817 B2
• Time in Patent Office: Days
• US Class Current: 73/715
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2207/012 the micromechanical device and the control or processing electronics being separate parts in the same package
• CPC Class Codes: B81B 2207/096 through the substrate
• CPC Class Codes: B81B 7/0054 between other parts not provided for in B81B7/0048 - B81B7/0051
• CPC Class Codes: B81C 2203/0792 Forming interconnections between the electronic processing unit and the micromechanical structure
• CPC Class Codes: G01L 19/146 using flexible element between the transducer and the support
• CPC Class Codes: 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
• CPC Class Codes: G01L 7/024 with mechanical transmitting or indicating means G01L7/043, G01L7/063, G01L7/084, G01L7/104, G01L7/166, G01L7/185 take precedence
• CPC Class Codes: H01L 21/76 Making of isolation regions between components
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49204 Contact or terminal manufacturing

Abstract

A pressure sensor comprises a first substrate containing a processing circuit integrated thereon and a cap attached to the first substrate. The cap includes a container, a holder, and one or more suspension elements for suspending the container from the holder. The container includes a cavity and a deformable membrane separating the cavity and a port open to an outside of the pressure sensor. The container is suspended from the holder such that the deformable membrane faces the first substrate and such that a gap is provided between the deformable membrane and the first substrate which gap contributes to the port. Sensing means are provided for converting a response of the deformable membrane to pressure at the port into a signal capable of being processed by the processing circuit.

Claims

1. A pressure sensor, comprising

a first substrate containing a processing circuit integrated thereon,

a cap attached to the first substrate wherein the cap includes a container, a holder, and one or more suspension elements for suspending the container from the holder, the container including a cavity and a deformable membrane separating the cavity and a port open to an outside of the pressure sensor, the container being suspended from the holder such that the deformable membrane faces the first substrate and such that a gap is provided between the deformable membrane and the first substrate which gap contributes to the port, and

sensing means for converting a response of the deformable membrane to pressure at the port into a signal capable of being processed by the processing circuit.

2. The sensor of claim 1,

wherein the cap has a plane extension and wherein the holder encircles the container in the plane of the cap,

wherein between the holder and the container the one or more suspension elements and one or more grooves alternate.

3. The sensor of claim 1,

wherein each suspension element contains a ridge between the holder and the container, and

wherein each suspension element has a shape allowing for a deviation of the container in at least one direction in the plane of the cap.

4. The sensor of claim 1,

wherein a height of the container is less than a height of the holder orthogonal to the plane of the cap thereby forming a recess on a backside of the cap opposite to the side of the cap the deformable membrane is arranged.

5. The sensor of claim 4,

wherein the recess is covered by a protection membrane.

6. The sensor of claim 2,

wherein the first substrate is a semiconductor substrate,

wherein the cap contains a second substrate and each groove is arranged orthogonal to the plane of the cap in the second substrate for separating the container from the holder.

7. The sensor of claim 6,

wherein the second substrate contains a bulk material and layers stacked on the bulk material,

wherein the cavity is a recess exclusively arranged in one or more of the layers of the second substrate,

wherein the deformable membrane is made from a third substrate attached to the layers of the second substrate, and

wherein the one or more grooves extend into the third substrate for separating the deformable membrane from a portion of the third substrate contributing to the holder.

8. The sensor of claim 7,

wherein the sensing means contains a first electrode formed by the deformable membrane and a second electrode formed by one of the layers of the second substrate. and

9. The sensor of claim 8,

wherein the second electrode is made of polysilicon.

10. The sensor of claim 8,

comprising at least two electrical connections between the cap and the first substrate,

wherein the first electrode is electrically connected to the processing circuit via at least one of the suspension elements and at least one of the electrical connections,

wherein the second electrode is electrically connected to the processing circuit via at least another one of the suspension elements and at least another one of the electrical connections. and

11. The sensor of claim 10,

wherein spacer elements are arranged between the first substrate and the third or the second substrate for building the gap, and wherein the electrical connections are provided by at least some of the spacer elements.

12. A method for manufacturing a pressure sensor comprising the steps of

providing a first substrate with a processing circuit integrated thereon,

providing a second substrate,

providing a third substrate,

manufacturing a cavity in the second substrate and one or more trenches around a first portion of the second substrate containing the cavity,

mounting said third substrate to said second substrate thereby covering the cavity in the second substrate to form a deformable membrane for sensing a pressure applied to the deformable membrane, and

mounting the assembly of the second substrate and the third substrate to the first substrate with the deformable membrane facing the first substrate and providing a gap between the deformable membrane and the first substrate.

13. The method of claim 12,

wherein manufacturing the cavity in the second substrate includes manufacturing the cavity in one or more layers stacked on a bulk material of the second substrate, and

wherein manufacturing the one or more trenches in the second substrate includes manufacturing the one or more trenches through the layers stacked on the bulk material and through at least a portion of the bulk material.

14. The method of claim 13,

wherein the one or more trenches are manufactured through the entire bulk material.

15. The method of claim 13,

wherein the one or more trenches are manufactured by etching.

16. The method of claim 12,

wherein mounting said third substrate to said second substrate to form the deformable membrane includes attaching a silicon-on-insulator substrate to a top layer of the second substrate, removing a bulk material and an insulating layer of the silicon-on-insulator substrate thereby leaving a silicon layer as deformable membrane spanning the cavity in the second substrate.

17. The method of claim 16,

wherein mounting said third substrate to said second substrate includes in a portion of the third substrate outside the deformable membrane

etching through the third substrate (3) for manufacturing one or more contact windows in the second substrate,

metalizing the one or more contact windows, and

laying open the one or more trenches in the second substrate by opening the third substrate at the location of the trenches.

18. The method of claim 12,

wherein a recess is manufactured in a backside of the second substrate opposite the side the deformable membrane is attached to, which recess is manufactured of a sufficient depth for laying open the one or more trenches previously manufactured into a portion of the bulk material thereby forming one or more grooves through the second substrate.

19. The method of claim 18,

wherein after mounting the assembly of the second substrate and the third substrate to the first substrate and prior to manufacturing the recess in the backside of the second substrate the second substrate is thinned and a hard mask is applied to the backside of the second substrate omitting an area for manufacturing the recess, and

wherein after having manufactured the recess a protection membrane is applied to the hard mask for covering the recess.

20. The method of claim 19,

wherein the gap between the first substrate and the assembly of the second and third substrate is manufactured by applying spacer elements between the first substrate and the assembly.

21. The method of claim 12,

wherein electrically conducting vias are built through the first substrate for electrically connecting the processing circuit to electrical contact structures on a backside of the first substrate opposite the side facing the deformable membrane.

22. The method of claim 21,

wherein the vias are built after having mounted the assembly of the second substrate and the third substrate to the first substrate and prior to manufacturing the recess in the backside of the second substrate.