INTEGRATED SINGLE-CRYSTAL MEMS DEVICE

• US 20090278628A1
• Filed: 06/14/2007
• Published: 11/12/2009
• Est. Priority Date: 06/29/2006
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Chevrie, Davud D. R., Philippe, Pascal, Sworowski, Marc
• Granted Patent: US 7,982,558 B2
• Time in Patent Office: Days
• US Class Current: 333/186
• CPC Class Codes: B81B 2201/0292 Sensors not provided for in B81B2201/0207 - B81B2201/0285
• CPC Class Codes: B81C 1/00198 comprising elements which are movable in relation to each other, e.g. comprising slidable or rotatable elements
• CPC Class Codes: H03H 3/0072 of microelectro-mechanical resonators or networks micromembranes or microbeams B81B2203/01; manufacture of microstructural devices in general B81C

Abstract

Method of manufacturing a MEMS device integrated in a silicon substrate. In parallel to the manufacturing of the MEMS device passive components as trench capacitors with a high capacitance density can be processed. The method is especially suited for MEMS resonators with resonance frequencies in the range of 10 MHz.

Claims

1. Method of manufacturing a MEMS device, which method comprises the steps of:

providing a device substrate 10 with a top side and a bottom side;

providing at least one trench 20 in the top side of the device substrate 10 defining the shape of a moveable structure 1000;

providing at least one electrically conductive area on the top side of the device substrate 10 and at least parts of the electrically conductive area form at least one moveable electrode 30 attached to the movable structure 1000;

providing a dielectric layer 40 on the top side of the device substrate 10 at least partly covering the electrically conductive area;

providing and structuring an electrically conductive electrode layer 50 on the top side of the device substrate 10;

providing at least one anchor point 100 in the dielectric layer 40;

providing and structuring an electrically conductive structural layer 70 on the top side of the device substrate 10 and the electrically conductive structural layer 70 anchors the moveable structure 1000 at the anchor point 100;

partly removing the dielectric layer 40 through the structured structural layer 70;

removing the device substrate 10 from the bottom side of the device substrate 10 in a defined area underneath the trench 20 defining the shape of the moveable structure 1000 at least until the trench 20 defining the shape of the moveable structure 1000 is reached and

releasing the moveable structure 1000.

2. Method of manufacturing a MEMS device according to claim 1, which method comprises the additional steps of:

providing a sacrificial layer 60 on top of the structured electrode layer 50;

structuring the sacrificial layer 60 and

partly removing the sacrificial layer 60 and the dielectric 40 layer through the structured structural layer 70.

3. Method of manufacturing a MEMS device according to claim 2, whereby the dielectric layer 40 and the sacrificial layer 60 can be removed with the same etchant and the etching rate of the sacrificial layer 60 with respect to the etchant is higher than the etching rate of the dielectric layer 40 with respect to the etchant.

4. Method of manufacturing a MEMS device according to claim 2, whereby the sacrificial layer 60 can be removed with a first etchant and the first etchant essentially doesn'"'"'t remove the dielectric layer 40 and the dielectric layer 40 can be removed with a second etchant and the second etchant essentially doesn'"'"'t remove the sacrificial layer 60.

5. Method of manufacturing a MEMS device according to claim 3, whereby the device substrate 10 is a silicon substrate, the dielectric layer 40 is thermally grown silicon oxide and the sacrificial layer 60 is deposited silicon oxide.

6. Method of manufacturing a MEMS device according to claim 4, whereby the device substrate 10 is a silicon substrate, the dielectric layer 40 is thermally grown silicon oxide and the sacrificial layer 60 is deposited silicon nitride.

7. Method of manufacturing a MEMS device according to claim 1, which method comprises the additional steps of:

encapsulating the top side of the device substrate 10;

providing a vacuum;

providing a packaging substrate 400 and

bonding the packaging substrate 400 to the bottom side of the device substrate 10.

8. A MEMS device comprising a device substrate 10 with at least one reference electrode, a moveable structure 1000 comprising the same material as the device substrate 10 and the moveable structure 1000 having at least one moveable electrode 30, the moveable structure 1000 is embedded in the device substrate 10 and indirectly attached to the device substrate 10 via at least one anchor essentially arranged above the device substrate 10, and a dielectric layer 40 being removed locally so as to allow the moveable structure 1000 attached to the moveable electrode 30 to be movable, and an electrical driving circuit is connected to the moveable electrode 30 and the reference electrode.

9. A MEMS device as claimed in claim 8 further comprising a capacitive structure electrically connected to the moveable electrode 30 and/or the reference electrode, the capacitive structure comprises a multitude of trenches 20 in the device substrate, and the surface of the trenches 20 is electrically conductive forming a first electrode of the capacitive structure, and the capacitive structure further comprises the dielectric layer 40 and a second electrode comprising the same material as the reference electrode.

10. A MEMS device as claimed in claim 8, wherein the MEMS device is a MEMS resonator.

11. A MEMS resonator as claimed in claim 10, wherein the moveable structure 1000 comprises an essentially disk shape.