COMPACT, EASY-TO-PRODUCE MEMS PACKAGE WITH IMPROVED PROTECTIVE PROPERTIES

Abstract

Preferably, the invention relates to a MEMS package having at least one layer for protecting a MEMS element, wherein the MEMS element has at least one MEMS interaction region on a substrate and a surface conformal coating of the MEMS element is applied with a dielectric layer. Particularly preferably, the invention relates to a MEMS transducer package in which a MEMS element, for example with a MEMS membrane and processor, preferably an integrated circuit, are present on a substrate. For protection, a surface conformal coating of a dielectric is preferably first applied to the MEMS element, for example by spray coating, mist coating, and/or vapor coating. Then, preferably, an electrically conductive layer is applied. Depending on the configuration, the layers may be removed in some regions above a MEMS interaction region of the MEMS element, for example for a sound port of a MEMS membrane.

Claims

1. A method of producing a MEMS package having at least one layer for protecting a MEMS device, comprising: obtaining an MEMS device comprising at least one MEMS interaction region on a substrate, wherein the MEMS element comprises a MEMS device and a processor on the substrate and an electrical connection is present between the MEMS device and the processor, coating of the MEMS device with a surface conformal coating of a dielectric layer, and applying an electrically conductive layer at least in regions on the dielectric layer, wherein the dielectric layer and the electrically conductive layer extend over the MEMS device and the processor.

2. The method according to claim 1, wherein the MEMS element is selected from the group consisting of: an acoustic MEMS transducer, an optical MEMS transducer, an MEMS sensor an MEMS filter.

3. The method according to claim 1, wherein the surface conformal coating is implemented by a coating process with a dielectric selected from the group consisting of: spray coating, mist coating, vapor coating and/or electroplating.

4. The method according to claim 1, wherein the surface conformal coating is implemented by a coating wetting the MEMS element at least in regions where a wetting coating is implemented in the MEMS interaction region.

5. The method according to claim 1, wherein the dielectric layer and/or the dielectric comprises a polymer.

6. The method according to claim 1, wherein the electrically conductive layer comprises metal and/or the electrically conductive layer (9) is applied by a coating process.

7. The method according to claim 1, wherein the MEMS device and/or processor are mounted in a flip-chip design.

8. The method according to claim 1, for a MEMS package comprising the MEMS device and the processor comprising the following steps: obtaining the MEMS device comprising a MEMS interaction region on the substrate providing the processor on the substrate, which has an electrical connection with the MEMS device, Surface conformal coating by spray coating of the MEMS device, processor and optionally the electrical connection (6) with the dielectric coating, such that the MEMS device, the processor and the electrical connection is completely enclosed between dielectric layer and substrate, applying an electrically conductive layer at least in regions onto the dielectric layer, which forms a layer system with the dielectric layer, and optionally arranging an opening above the MEMS interaction regions by removing the dielectric layer and/or the layer system at least in some regions above the MEMS interaction region.

9. The method according to claim 1, wherein a removal of the dielectric layer is performed by a lithographic process or a lift-off, wherein preferably the dielectric layer is formed by a photostructurable polymer and a pre-structuring of the dielectric layer is performed by corresponding exposure of the photostructurable polymer to light.

10. The method according to claim 1, wherein the layer thickness of the dielectric layer is between 10 nm and 1 mm and/or the layer thickness of an electrically conductive layer is between 10 nm and 20 μm.

11. The method according to claim 1, wherein the MEMS element is an optical MEMS transducer, and the MEMS interaction region comprises an optical emitter and/or an optical receiver, the MEMS element is an acoustic MEMS transducer and the MEMS interaction region comprises a MEMS membrane, the MEMS element is a MEMS gas sensor and the MEMS interaction region comprises a MEMS membrane and or an electro-chemical MEMS sensor region or the MEMS element is a MEMS filter, and wherein the MEMS interaction region comprises a MEMS filter structure comprising MEMS electrodes and/or a MEMS bulk region.

12. The method according to claim 1, wherein the MEMS element is a MEMS acoustic transducer and comprises a MEMS device and a processor, and the production method comprises the following steps: obtaining the MEMS device comprising a MEMS membrane on a substrate, providing the processor on the substrate, which has an electrical connection to the MEMS device, Surface conformal coating by spray coating, of the MEMS device, the processor and optionally an electrical connection with the dielectric layer, such that the MEMS device, the processor and the electrical connection are completely enclosed between the dielectric layer and the substrate, optionally applying an electrically conductive layer at least in some regions on the dielectric layer, which forms a layer system with the dielectric layer, and optionally arrangement of a sound port above the MEMS membrane by removing the dielectric layer or layer system at least in some regions above the membrane.

13. MEMS package manufacturable by a production method according to one or more of the preceding claims.

14. MEMS package (14), comprising a substrate, an MEMS element arranged on the substrate comprising a MEMS interaction region, wherein the MEMS element comprises a MEMS device and a processor on the substrate, a dielectric layer for protecting the MEMS element, produced by surface conformal coating of the MEMS element by a dielectric coating process, an electrically conductive layer at least in regions on the dielectric layer, wherein the dielectric layer and the electrically conductive layer extend over the MEMS device and the processor.

15. The method according to claim 2, wherein the MEMS sensor is an MEMS gas sensor.

16. The method according to claim 5, wherein the polymer is selected from the group consisting of: a photostructurable polymer, a polymethyl methacrylate, a polyimide, novolak, polymethyl glutarimide, a polymer depositable from a gas and/or a liquid phase, parylene and an epoxy resin.

17. The method according to claim 16, wherein the polymer depositable from a gas and/or a liquid phase is tetraethyl orthosilicate (TEOS).

18. The method according to claim 16, wherein the epoxy resin is SU-8.

19. The method according to claim 6, wherein the metal is aluminum and/or a noble metal.

20. The method according to claim 19, wherein the noble metal is gold, platinum, iridium, palladium, osmium, silver, rhodium and/or ruthenium.

21. The method according to claim 6, wherein the coating process is a PVD, CVD and/or sputtering process.

22. The method of claim 7, wherein the electrical connection is made via the substrate.

23. The method according to claim 1 wherein the MEMS device and/or processor are present in a conventional design and not in a flip-chip design.

24. The method of claim 23, wherein the electrical connection is made via at least one wire bond.

25. The method according to claim 8, wherein the MEMS package comprises a layer system for protecting the MEMS element.

26. The method according to claim 11, wherein the MEMS filter is a MEMS frequency filter.

27. The method according to claim 26, wherein the MEMS frequency filter is a SAW or a BAW filter.

Description

DETAILED DESCRIPTION

[0213] The invention will be explained below with reference to further figures and examples. The examples and figures serve to illustrate preferred embodiments of the invention without limiting them.

[0214] FIGS. 1 to 4 illustrate a preferred embodiment of the production method for a MEMS package, using a MEMS transducer package 14 as an example.

[0215] FIG. 1 shows a MEMS transducer 1 without a finished package 14. MEMS device 2 (also referred to as MEMS device) with MEMS membrane 3 are present on a substrate 4. Likewise, an IC 5 (here in the form of an ASIC) is arranged on the substrate 4. MEMS device 2 and IC 5 are electrically connected here via a wire bond 6.

[0216] FIG. 2 schematically illustrates the application of the coating system 16 to protect the MEMS transducer 1. First, a surface conformal coating (e.g. spray coating) 7 is applied with a dielectric, which coats all components present on the substrate with a dielectric layer 8. Thus, this layer encloses these components, i.e. here MEMS device 2, IC 5 and wire bond 6 between itself and substrate 4 and is substantially close-fitting. Next, an electrically conductive layer 9 is applied to the dielectric layer 8, which also covers the outer edge regions of the dielectric layer 8 and is preferably flush with the substrate 4 at the outer edge of the coating in order to obtain a good seal there.

[0217] FIG. 3 shows a MEMS transducer package 14, which separates the MEMS transducer 1 from the package environment 17 and thus protects it. The MEMS device 2 is arranged such that the back volume 13 is located between the membrane 3 and the substrate 4. Therefore, a sound port 11 is introduced into the layer system 16 above the membrane, in which both layers 8, 9 are removed above the membrane 3, for example by a lithography process. The membrane 3 is present here as a non-released membrane, which is protected for the time being by a sacrificial layer 12.

[0218] In FIG. 4, a released membrane 15 was produced by removing the sacrificial layer 12.

[0219] FIG. 5 shows a package which is preferably fully surface conformal, in which a fully surface conformal coating system 18 is produced by means of vapor phase deposition of a polymer (e.g. Parylene). It shows how close-fitting a layer system produced in this way is, in which even the structure of the wire bond 6 is retained after coating in the package 14.

LIST OF REFERENCE SIGNS

[0220] 1 MEMS element, for example MEMS transducer [0221] 2 MEMS device [0222] 3 MEMS interaction region, for example MEMS membrane. [0223] 4 Substrate [0224] 5 Processor, preferably integrated circuit (IC) [0225] 6 Electrical connection, preferably wire bond [0226] 7 Surface conformal coating (e.g. spray coating) [0227] 8 Dielectric layer [0228] 9 Electrically conductive layer [0229] 10 Outer edge of the coating [0230] 11 Opening in front of the MEMS interaction region, preferably sound port [0231] 12 Sacrificial layer of the non-released interaction region, for example, of a non-exposed [0232] membrane [0233] 13 Back volume [0234] 14 MEMS package, for example MEMS transducer package [0235] 15 Released MEMS interaction region, for example, released MEMS membrane [0236] 16 Layer system [0237] 17 Package environment [0238] 18 Surface conformal layer system

LITERATURE

[0239] Alfons Dehé, Martin Wurzer, Marc Fuldner and Ulrich Krumbein, The Infineon Silicon MEMS Microphone, AMA Conferences 2013—SENSOR 2013, OPTO 2013, IRS 2 2013. [0240] Gregor Feiertag, Wolfgang Pahl, Matthias Winter, Anton Leidl, Stefan Seitz, Christian Siegel, Andreas Beer, Flip chip MEMS microphone package with large acoustic reference volume, Proc. Eurosensors XXIV, Sep. 5-8, 2010, Linz, Austria. [0241] M. Härth, D. W. Schubert, Simple Approach for Spreading Dynamics of Polymeric Fluids. In: Macromol. Chem. Phys. 213, no. 6, March 2012, pp. 654-665.