Micromechanical component and process for its fabrication

• US 6,556,418 B2
• Filed: 02/28/2001
• Issued: 04/29/2003
• Est. Priority Date: 08/31/1998
• Status: Expired due to Term

• Current Assignee: Siemens AG
• Original Assignee: Infineon Technologies AG
• Inventors: Kapels, Hergen, Aigner, Robert, Oppermann, Klaus-Günter
• Primary Examiner(s): Dinkins, Anthony
• Assistant Examiner(s): Ha, Nguyen
• Application Number:
  US09/795,098
• Publication Number:
  US 20010021538A1
• Time in Patent Office: 790 Days
• Field of Search: 361/283.1, 361/283, 361/283.3, 361/283.4, 361/286, 257/17, 257/15, 257/417, 257/419, 438/56, 438/53, 438/52
• US Class Current: 361/283.1
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2207/053 of movable structures
• CPC Class Codes: B81C 1/00158 Diaphragms, membranes manufacture process for semi-permeable inorganic membranes B01D67/0039
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm

Abstract

A micromechanical component placed on a substrate face includes at least one cell. A counter-electrode of a cell capacitor is placed under a cavity. The counter-electrode can be made from a first part of a lower conductive layer. An optionally circular membrane used as an electrode of the capacitor is placed above the cavity. The membrane is homogeneous, has a substantially uniform thickness, and can be part of an upper conductive layer preferably supported by a second part of the lower conductive layer. A caustic channel used to remove the sacrificial coating in order to form the cavity is laterally connected thereto. The channel has a vertical dimension equal to the vertical dimension of the cavity. A closure is adjacent to the channel and disposed outside the membrane. The component can be used as a pressure sensor, and can have several cells each adjacent to six other cells. A process for fabricating a micromechanical component is also provided.

Claims

1. A micromechanical component, comprising:

at least one cell having;

a cavity with a given vertical dimension;

a membrane acting as an electrode of a capacitor of said at least one cell, said membrane homogeneously disposed with a substantially uniform thickness over said cavity;

a counter-electrode of said capacitor disposed under said cavity;

at least one etching channel laterally adjoining said cavity, said at least one etching channel having a vertical dimension equal to said given vertical dimension; and

at least one closure adjoining said at least one etching channel from above and disposed outside said membrane.

2. The micromechanical component according to claim 1, including an upper conductive layer adjoining said cavity laterally and from above said cavity, said membrane being part of said upper conductive layer.

3. The micromechanical component according to claim 2, including:

a substrate having a surface;

a first insulating layer being disposed on said surface; and

a structured lower conductive layer having a first part and a second part, said lower conductive layer being disposed on said first insulating layer, said first part being said counter-electrode, and said upper conductive layer being supported on said second part of said lower conductive layer and being insulated from said first part of said lower conductive layer.

4. The micromechanical component according to claim 3, including a second insulating layer being disposed on said lower conductive layer, said cavity being bounded from below by said second insulating layer.

5. The micromechanical component according to claim 1, wherein:

said membrane has a substantially circular cross section;

said at least one etching channel is at least three etching channels disposed at equal distances from one another;

said at least one cell is a plurality of identical cells, respective groups of three of said cells adjoining one another have respective centers lying at corners of an equilateral triangle; and

three etching channels of three different cells meet one another in a region over which said closure is disposed, said closure disposed between said three different cells.

6. The micromechanical component according to claim 5, including

an upper conductive layer adjoining said cavity laterally and from above said cavity, said membrane being part of said upper conductive layer;

a substrate having a surface;

a first insulating layer being disposed on said surface;

a structured lower conductive layer having a first part and a second part, said lower conductive layer being disposed on said first insulating layer, said first part being said counter-electrode, and said upper conductive layer being supported on said second part of said lower conductive layer and being insulated from said first part of said lower conductive layer; and

conductive webs running in said etching channels, said counter-electrodes of said cells cohering through said conductive webs and, together with said webs, form said first part of said lower conductive layer.

7. The micromechanical component according to claim 3, wherein:

said at least one etching channel is at least three etching channels disposed at equal distances from one another;

said at least one cell is a plurality of identical cells, respective groups of three of said cells adjoining one another have respective centers lying at corners of an equilateral triangle; and

including conductive webs running in said etching channels, said counter-electrodes of said cells cohering through said conductive webs and, together with said webs, form said first part of said lower conductive layer.

8. The micromechanical component according to claim 1, wherein:

said at least one etching channel is at least three etching channels disposed at equal distances from one another;

said at least one cell is a plurality of identical cells, respective groups of three of said cells adjoining one another have respective centers lying at corners of an equilateral triangle; and

including;

an upper conductive layer adjoining said cavity laterally and from above said cavity, said membrane being part of said upper conductive layer;

a substrate having a surface;

a first insulating layer being disposed on said surface;

a structured lower conductive layer having a first part and a second part, said lower conductive layer being disposed on said first insulating layer, said first part being said counter-electrode, and said upper conductive layer being supported on said second part of said lower conductive layer and being insulated from said first part of said lower conductive layer; and

conductive webs running in said etching channels, said counter-electrodes of said cells cohering through said conductive webs and, together with said webs, form said first part of said lower conductive layer.

9. A high-pressure sensor for measuring pressures over 40 bar, comprising:

at least one cell having;

a cavity with a given vertical dimension;

a membrane acting as an electrode of a capacitor of said at least one cell, said membrane homogeneously disposed with a substantially uniform thickness over said cavity, said membrane having a diameter less than 30 μ

m;

a counter-electrode of said capacitor disposed under said cavity;

at least one etching channel laterally adjoining said cavity, said at least one etching channel having a vertical dimension equal to said given vertical dimension; and

at least one closure adjoining said at least one etching channel from above and disposed outside said membrane.

10. A process for fabricating a micromechanical component, which comprises:

producing a sacrificial layer over a counter-electrode of a capacitor of a cell;

structuring the sacrificial layer to fill a region of a cavity to be produced in the cell and to fill an etching channel laterally adjacent to the cavity;

conformally applying an upper conductive layer over the sacrificial layer;

producing an opening into the upper conductive layer through the etching channel reaching as far as the sacrificial layer;

etching the sacrificial layer to produce the cavity, a part of the upper conductive layer disposed over the cavity becoming capable of being deflected and acting as a membrane of the cell and as an electrode of the capacitor; and

closing the etching channel in a region of the opening from above with a closure.

11. The process according to claim 10, which further comprises:

producing a first insulating layer on a substrate;

depositing a lower conductive layer over the first insulating layer and structuring the lower conductive layer to produce a first part of the lower conductive layer forming a counter-electrode and to produce a second part of the lower conductive layer separated from the first part;

producing a second insulating layer over the first conductive layer;

producing the sacrificial layer over the second insulating layer, the sacrificial layer to be etched selectively with respect to the second insulating layer;

analogously structuring the second insulating layer and the sacrificial layer to have the second insulating layer completely cover the first part of the lower conductive layer with the second part of the lower conductive layer acting as an etch stop; and

producing the upper conductive layer over the sacrificial layer to partly adjoin the upper conductive layer laterally with the sacrificial layer.