Vented MEMS apparatus and method of manufacture

• US 8,969,980 B2
• Filed: 09/20/2012
• Issued: 03/03/2015
• Est. Priority Date: 09/23/2011
• Status: Active Grant

• Current Assignee: Knowles Electronics Llc (Knowles Corporation)
• Original Assignee: Knowles Electronics Llc (Knowles Corporation)
• Inventors: Lee, Sung Bok
• Primary Examiner(s): Le, Thao X
• Assistant Examiner(s): LE, LONG HUYNH
• Application Number:
  US13/623,598
• Publication Number:
  US 20130075836A1
• Time in Patent Office: 894 Days
• Field of Search: 257/704, 257/415, 257/416, 737/21, 381/174, 381/175
• US Class Current: 257/416
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 2203/0127 Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
• CPC Class Codes: B81B 7/0029 Protection against environmental influences not provided for in groups B81B7/0012 - B81B7/0025
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/15151 the die mounting substrate comprising an aperture, e.g. for underfilling, outgassing, window type wire connections
• CPC Class Codes: H04R 19/005 using semiconductor materials
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence
• CPC Class Codes: H04R 2201/003 Mems transducers or their use of the electrostatic type H04R19/005

Abstract

A micro-electromechanical system (MEMS) device includes a housing and a base. The base includes a port opening extending therethrough and the port opening communicates with the external environment. The MEMS die is disposed on the base and over the opening. The MEMS die includes a diaphragm and a back plate and the MEMS die, the base, and the housing form a back volume. At least one vent extends through the MEMS die and not through the diaphragm. The at least one vent communicates with the back volume and the port opening and is configured to allow venting between the back volume and the external environment.

Claims

1. A micro-electromechanical system (MEMS) device, comprising:

a housing;

a base with a port opening extending therethrough, wherein the port opening communicates with the external environment;

a MEMS die disposed on the base and over the opening, the MEMS die securing a diaphragm and a back plate, wherein the MEMS die, the base, and the housing form a back volume;

wherein a longitudinal axis extends longitudinally through a center of the MEMS die, the diaphragm, the back plate, and the port opening;

at least one vent extending through the MEMS die and not through the diaphragm or the back plate, the at least one vent being a passageway with a first end and a second end, the passageway being surrounded on at least three sides by the MEMS die and opening at the first end and the second end, the at least one vent extending in a generally outward and radial direction from the longitudinal axis, the at least one vent communicating with the back volume and the port opening, the at least one vent being configured to allow venting between the back volume and the external environment, the venting being effective to equalize pressure between the back volume and the outside environment wherein the first end opens to the back volume and the second end opens to the outside environment.

2. The MEMS device of claim 1 wherein a sensitive area is formed between the diaphragm and the back plate and wherein the lack of vent in the diaphragm prevents contaminants from entering the sensitive area.

3. The MEMS device of claim 1 wherein the at least one vent is approximately circular in cross sectional shape.

4. The MEMS device of claim 1 wherein the at least one vent is slot-shaped in cross sectional shape.

5. The MEMS device of claim 1 further comprising a processing device coupled to the MEMS die.

6. The MEMS device of claim 4 wherein the processing device comprises an integrated circuit.

7. The MEMS device of claim 1 wherein the at least one vent is approximately 40 microns in diameter.