MEMS PRESSURE SENSORS WITH INTEGRATED BAFFLES

• US 20140318656A1
• Filed: 12/09/2013
• Published: 10/30/2014
• 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.
• Granted Patent: US 10,107,315 B2
• Time in Patent Office: Days
• US Class Current: 138/37
• 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 positioned between the entry port and the pressure sensor, 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 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 being located within no more than one millimeter of a location on 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 require all portions of the gas or liquid to make one or more turns as they travel from the inlets to the outlets that have 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. A process for making a product that includes a baffle comprising:

depositing, pattering, etching, wafer bonding, or wafer thinning a series of layers in a manner that creates a baffle that has;

one or more inlets for receiving a gas or liquid;

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

one or more sealed flow channels for the gas or liquid to travel from the inlets to the outlets.

11. The process of claim 10 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.

12. The process of claim 10 wherein the sealed flow channels require all portions of the gas or liquid to make one or more turns as they travel from the inlets to the outlets that have a turning radius of no more than fifty micrometers.

13. The process of claim 10 further comprising coating at least a portion of the baffle with an impurity-absorbing material.

14. The process of claim 10 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.

15. The process of claim 14 wherein at least one of the outlets of the baffle is spaced no more than one millimeter from a location on the diaphragm.

16. The process of claim 14 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.

17. The process of claim 14 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.

18. The process of claim 14 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.

19. A product that includes a baffle, 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;

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;

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.

20. The product of claim 19 wherein the sealed flow channel has a configuration that generates an electric field through which the gas or liquid must pass when a voltage potential is applied to the baffle.

21. The product of claim 19 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.

22. The product of claim 21 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.

23. A baffle comprising:

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

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

one or more sealed flow channels for the gas or liquid to travel from the inlets to the outlets, the sealed flow channels requiring all portions of the gas or liquid to make one or more turns as they travel from the inlets to the outlets that have a turning radius of no more than one hundred micrometers.

24. The baffle of claim 23 wherein the turning radius is no more than fifty micrometers.

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