Micromechanical sensors and methods of manufacturing same

• US 7,473,572 B2
• Filed: 01/24/2006
• Issued: 01/06/2009
• Est. Priority Date: 12/11/2001
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Fueldner, Marc, Dehe, Alfons
• Primary Examiner(s): Nguyen; Tuan H
• Application Number:
  US11/339,046
• Publication Number:
  US 20060141656A1
• Time in Patent Office: 1,078 Days
• Field of Search: 438/48, 438 50- 53
• US Class Current: 438/48
• 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 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00
• CPC Class Codes: H04R 19/005 using semiconductor materials
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence
• CPC Class Codes: H04R 31/00 Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182

Abstract

A micromechanical sensor and, in particular, a silicon microphone, includes a movable membrane and a counter element in which perforation openings are formed, opposite to the movable membrane via a cavity. The perforation openings are formed by slots, the width of which maximally corresponds to double the spacing defined by the cavity between the membrane and the counter element.

Claims

1. A method of manufacturing a micromechanical sensor, comprising the following steps:

producing slot-shaped perforation openings in a layer;

producing an essentially planar oxide layer on the layer in which the slot-shaped perforation openings are formed, with a thickness corresponding to a future distance between a counter element and a membrane of the micromechanical sensor, using a front-side oxide deposition on the layer provided with the slot-shaped perforation openings, wherein a width of the slot-shaped perforation openings maximally corresponds to double the thickness of the essentially planar oxide layer, and wherein the slot-shaped perforation openings are closed by oxide when producing the essentially planar oxide layer, thereby facilitating an essentially planar top surface of the essentially planar oxide layer that opposes the layer having the slot-shaped perforation openings;

depositing the membrane onto the essentially planar top surface of the essentially planar oxide layer; and

performing an etching for opening the slot-shaped perforation openings in the layer by removing any oxide from the essentially planar oxide layer that had closed the slot-shaped perforation openings and for producing a cavity in the essentially planar oxide layer between the membrane and the counter element which comprises the layer in which the slot-shaped perforation openings are formed, wherein the length of the slot-shaped perforation openings is at least double the width of the slot-shaped perforation openings but less than half a dimension of the counter element.

2. The method according to claim 1, wherein the width of the slot-shaped perforation openings is 2 μ

m or less.

3. The method according to claim 1, wherein the slot-shaped perforation openings are arranged in rows and columns.

4. The method according to claim 3, wherein the slot-shaped perforation openings are formed by first slots and second slots which are perpendicular to the first slots.

5. The method according to claim 4, wherein the first and second slots are arranged alternatingly in the counter element.

6. The method according to claim 1, wherein the slot-shaped perforation openings are slots formed in different directions.

7. The method according to claim 1, wherein the slot-shaped perforation openings form slot crosses.

8. The method according to claim 1, wherein slot-shaped perforation openings are arranged in rows and the slot crosses of neighboring rows are offset to one another.

9. The method according to claim 1, wherein the area of the slot-shaped perforation openings basically is 10 to 50% of the entire area of the counter element.