MEMS pressure sensors with integrated baffles

• US 10,107,315 B2
• Filed: 12/09/2013
• Issued: 10/23/2018
• Est. Priority Date: 04/30/2013
• Status: Active Grant

• Current Assignee: MKS Instruments Incorporated
• Original Assignee: MKS Instruments Incorporated
• Inventors: Gu, Lei, Bart, Stephen F.
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): Roberts, Herbert K
• Application Number:
  US14/101,207
• Publication Number:
  US 20140318656A1
• Time in Patent Office: 1,779 Days
• CPC Class Codes: F15D 1/0005 Baffle plates
• CPC Class Codes: G01L 19/0007 Fluidic connecting means
• CPC Class Codes: G01L 19/0627 Protection against aggressive medium in general
• CPC Class Codes: G01L 19/0636 using particle filters
• CPC Class Codes: Y10T 29/49 Method of mechanical manufacture

Abstract

A pressure sensor system may sense the pressure of a gas or liquid. The system may include a housing that has an entry port for the gas or liquid; a pressure sensor within the housing; and a baffle positioned between the entry port and the pressure sensor. The baffle may have one or more inlets oriented to receive gas or liquid that enters the entry port; one or more outlets oriented to deliver the received gas or liquid to the pressure sensor; and one or more sealed flow channels that prevent the gas or liquid from escaping from the baffle, other than through the one or more outlets. At least one of the outlets may be located within no more than one millimeter of a location on the pressure sensor. The pressure sensor and baffle may be made at the same time during a process of depositing, pattering, etching, wafer bonding, and/or wafer thinning a series of layers using microelectromechanical systems (MEMS) technology.

Claims

1. A pressure sensor system for sensing the pressure of a gas or liquid comprising:

a housing having an entry port for the gas or liquid;

a pressure sensor within the housing; and

a baffle that has multiple layers and is positioned between the entry port and the pressure sensor, wherein each of the multiple layers has two lateral faces and is connected to at least one other layer, and wherein pairs of adjacent layers are directly connected to each other at respective lateral faces, the baffle having;

one or more inlets oriented to receive gas or liquid that enters the entry port;

one or more outlets oriented to deliver the received gas or liquid to the pressure sensor; and

a plurality of discrete sealed flow channels passing through the multiple layers via one or more apertures in each respective layer, and wherein the plurality of sealed flow channels connect the one or more inlets to the one or more outlets and prevent the gas or liquid from escaping from the baffle, other than through the one or more outlets or the one or more inlets,

wherein the one or more outlets are located within no more than one millimeter of a respective location on the diaphragm of the pressure sensor.

2. The pressure sensor system of claim 1 wherein the pressure sensor includes:

a flexible diaphragm within the housing; and

a sensing system having a configuration that senses changes in the diaphragm caused by changes in the pressure of the gas or liquid.

3. The pressure sensor system of claim 1 wherein the baffle has:

features that are less than 100 micrometers in length;

conformal layers; and

one or more layers of silicon, polysilicon, silicon oxide, silicon nitride, alumina, sapphire, nickel, or nickel alloy.

4. The pressure sensor system of claim 1 wherein the baffle has multiple layers, each with at least one hole through it.

5. The pressure sensor system of claim 1 wherein the sealed flow channels force the gas or liquid to change directions while traveling through the baffle.

6. The pressure sensor system of claim 5 wherein the baffle has a layer and the sealed flow channels force the gas or liquid to travel through the layer in opposite directions.

7. The pressure sensor system of claim 1 wherein the sealed flow channels include one or more turns as they travel from the inlets to the outlets, wherein each of the turns has a turning radius of no more than fifty micrometers.

8. The pressure sensor system of claim 1 wherein at least a portion of the sealed flow channels are coated with an impurity-absorbing material.

9. The pressure sensor system of claim 1 wherein the pressure sensor has a configuration that generates an electric field between the baffle and the pressure sensor when a voltage potential is applied between the baffle and pressure sensor.

10. The pressure sensor system of claim 1 wherein the baffle is electrically isolated from the diaphragm.

11. The pressure sensor system of claim 1 wherein the baffle layers are configured to be energized so as to electrostatically capture impurities in the gas or liquid.

12. The pressure sensor system of claim 1 wherein the system is configured to use a voltage on the baffle, directly adjacent the diaphragm, to adjust a zero point of the diaphragm.

13. The pressure sensor system of claim 1 wherein the one or more apertures in each of the multiple layers of the baffle are offset with respect to the one or more apertures in each adjacent layer of the baffle.

14. A process for making a product that includes a baffle that has multiple layers, the process comprising:

depositing, pattering, etching, wafer bonding, or wafer thinning a series of layers in a manner that creates a baffle that has multiple layer, wherein each of the multiple layers has two lateral faces and is connected to at least one other layer, and wherein pairs of adjacent layers are directly connected to each other at respective lateral faces, and wherein the baffle includes;

one or more inlets for receiving a gas or liquid;

one or more outlets for delivering the received gas or liquid; and

a plurality of discrete sealed flow channels passing through one or more apertures in each of the multiple layers and configured to permit the gas or liquid to travel from the inlets to the outlets and prevent the gas or liquid from escaping from the baffle, other than through the one or more outlets or the one or more inlets.

15. The process of claim 14 wherein the baffle includes:

features that are less than 100 micrometers in length;

conformal layers; and

one or more layers of silicon, polysilicon, silicon oxide, silicon nitride, alumina, sapphire, nickel, or nickel alloy.

16. The process of claim 14 wherein the sealed flow channels include one or more turns as they travel from the inlets to the outlets, wherein each of the turns has a turning radius of no more than fifty micrometers.

17. The process of claim 14 further comprising coating at least a portion of the baffle with an impurity-absorbing material.

18. The process of claim 14 wherein the product is a pressure sensor system and wherein one of the layers that is produced by the depositing, pattering, etching, wafer bonding, or wafer thinning is a flexible diaphragm that is spaced from the baffle.

19. The process of claim 18 wherein at least one of the outlets of the baffle is spaced no more than one millimeter from a location on the diaphragm.

20. The process of claim 18 further comprising:

computing a separation distance between the baffle and the diaphragm; and

depositing, pattering, etching, wafer bonding, or wafer thinning a series of layers in a manner that causes the baffle and the diaphragm to be separated by substantially the computed separation distance.

21. The process of claim 18 further comprising:

computing a length and cross-sectional area of the sealed flow channel that collectively cause the pressure sensor to have a desired response time to changes in the pressure of the gas or liquid; and

depositing, pattering, etching, wafer bonding, or wafer thinning a series of layers in a manner that causes the baffle to have the computed length and cross-sectional area.

22. The process of claim 18 wherein one of the layers that is produced by the depositing, pattering, etching, wafer bonding, or wafer thinning is an electrode that is spaced from the diaphragm and that is not part of the baffle.

23. A product that includes a baffle that has multiple layers, wherein each of the multiple layers has two lateral faces and is connected to at least one other layer, and wherein pairs of adjacent layers are directly connected to each other at respective lateral faces, the baffle having:

one or more inlets oriented to receive a gas or liquid;

one or more outlets oriented to deliver received gas or liquid;

a plurality of discrete sealed flow channels passing through one or more apertures in each of the multiple layers, wherein the plurality of sealed flow channels prevent the gas or liquid from escaping from the baffle other than through the one or more outlets or the one or more inlets, wherein the sealed flow channels include one or more turns as they travel from the inlets to the outlets, wherein the turns have a turning radius of no more than one hundred micrometers;

features that are less than one hundred microns in length;

conformal layers; and

one or more layers of silicon, polysilicon, silicon oxide, silicon nitride, alumina, sapphire, nickel, or nickel alloy.

24. The product of claim 23 wherein the sealed flow channels have a configuration that generates an electric field through which the gas or liquid must pass when a voltage potential is applied to the baffle.

25. The product of claim 23 wherein the product is a pressure sensor system for sensing the pressure of a gas or liquid and the product further comprises:

a housing having an entry port for the gas or liquid;

a flexible diaphragm within the housing; and

a sensing system having a configuration that senses changes in the diaphragm caused by changes in the pressure of the gas or liquid, wherein the baffle is positioned between the entry port and the flexible diaphragm.

26. The product of claim 25 wherein the pressure sensor has a configuration that generates an electric field between the baffle and the diaphragm when a voltage potential is applied between the baffle and the diaphragm.

27. A baffle comprising:

a plurality of layers physically connected together, wherein each of the plurality of layers has two lateral faces and is connected to at least one other layer, and wherein pairs of adjacent layers are directly connected to each other at respective lateral faces;

one or more inlets oriented to receive a gas or liquid;

one or more outlets oriented to deliver received gas or liquid; and

a plurality of discrete sealed flow channels passing through one or more apertures in each of the multiple layers, wherein the one or more sealed flow channels permit the gas or liquid to travel from the one or more inlets to the one or more outlets, and wherein the plurality of discrete sealed flow channels prevent the gas or liquid from escaping from the plurality of layers other than through the one or more outlets or the one or more inlets, each sealed flow channel including one or more turns as it travels from the one or more inlets to the one or more outlets, wherein each turn has a turning radius of no more than one hundred micrometers.

28. The baffle of claim 27 wherein the turning radius is no more than fifty micrometers.

29. The baffle of claim 27 wherein the sealed flow channels have a configuration that generates an electric field through which the gas or liquid must pass when a voltage potential is applied to the baffle.