MEMS device incorporating a fluidic path, and manufacturing process thereof

• US 9,321,628 B2
• Filed: 06/26/2014
• Issued: 04/26/2016
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Faralli, Dino, Vigna, Benedetto, Castoldi, Laura Maria
• Primary Examiner(s): WOJCIECHOWICZ, EDWARD JOSEPH
• Application Number:
  US14/316,583
• Publication Number:
  US 20150001645A1
• Time in Patent Office: 670 Days
• Field of Search: 257/415, 438/53
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• 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 2207/012 the micromechanical device and the control or processing electronics being separate parts in the same package
• CPC Class Codes: B81B 7/0061 suitable for fluid transfer from the MEMS out of the package or vice versa, e.g. transfer of liquid, gas, sound
• CPC Class Codes: B81C 1/00269 Bonding of solid lids or wafers to the substrate
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• CPC Class Codes: H01L 2224/32145 the bodies being stacked
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/10155 being other than a cuboid
• 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: H01L 2924/181 Encapsulation

Abstract

A MEMS device wherein a die of semiconductor material has a first face and a second face. A membrane is formed in or on the die and faces the first surface. A cap is fixed to the first face of the first die and is spaced apart from the membrane by a space. The die is fixed, on its second face, to an ASIC, which integrates a circuit for processing the signals generated by the die. The ASIC is in turn fixed on a support. A packaging region coats the die, the cap, and the ASIC and seals them from the outside environment. A fluidic path is formed through the support, the ASIC, and the first die, and connects the membrane and the first face of the die with the outside, without requiring holes in the cap.

Claims

1. A MEMS device comprising:

a first semiconductor die having a first face and a second face;

a membrane formed in or on the first semiconductor die and at the first face;

a cap coupled to the first face of the first semiconductor die with an inner surface of the cap facing and spaced apart from the membrane by a space, the cap having an outer surface opposite the inner surface;

a support coupled to the first semiconductor die and facing the second face of the first semiconductor die;

packaging material enclosing the outer surface the cap and portions of the first semiconductor die; and

a fluidic path extending through the support and the first semiconductor die and fluidly coupling the membrane to an environment outside of the MEMS device.

2. The MEMS device according to claim 1, further comprising elastic elements, wherein the first semiconductor die includes a suspended region and a peripheral region that are separated from each other by a trench, the suspended region supporting the membrane and being coupled to the peripheral region by the elastic elements, wherein the elastic elements extend into the trench and are monolithic with the suspended region and the peripheral region.

3. The MEMS device according to claim 2, wherein the fluidic path comprises the trench, a first hole extending through the support, and the space between the membrane and the cap.

4. The MEMS device according to claim 3, further comprising a second semiconductor die located between the first semiconductor die and the support, the second semiconductor die having a second hole that is a part of the fluidic path, the second die including a processing circuit.

5. The MEMS device according to claim 2, wherein the suspended region has a first thickness and the peripheral region has second thickness, the first thickness being smaller than the second thickness, the MEMS device further comprising an air gap located underneath the suspended region and in the fluidic path.

6. The MEMS device according to claim 2 wherein the suspended region and the peripheral region have a same thickness, the MEMS device further comprising a spacer layer located over at least part of the second face of the first semiconductor die to form a gap that is a part of the fluidic path.

7. The MEMS device according to claim 1, wherein the first semiconductor device and the membrane together form at least one of a pressure sensor, a humidity sensor, a flow sensor, an environmental sensor, a gas sensor, a microfluidic device, and a miniaturized microphone.

8. The MEMS device according to claim 1, wherein the cap does not include any through holes, and the membrane is fluidly coupled the environment outside of the MEMS device only by the fluidic path.

9. An apparatus comprising:

a processing unit;

an input/output interface coupled to the processing unit;

a memory device coupled to the processing unit;

a circuit board; and

a plurality of adhesive regions;

a MEMS device secured to the circuit board by the plurality of adhesive regions, the plurality of adhesive regions being spaced apart from each other and forming gaps, the MEMS device including;

a first semiconductor die having a first face and a second face and a trench that extends from the first face to the second face;

a membrane formed in or on the first semiconductor die and at the first face;

a cap coupled to first face of the first semiconductor die, the cap having an inner surface facing and spaced apart from the membrane by a space and an outer surface that opposes the inner surface;

a support having a through hole coupled to the first semiconductor die and facing the second face of the first semiconductor die, the through hole of the support being in fluid communication with the trench of the first semiconductor die;

packaging material on the entire outer surface of the cap and portions of the semiconductor die; and

a fluidic path that includes the through hole of the support, the trench of the first semiconductor die, the gaps between the MEMS device and the circuit board, the fluidic path placing the membrane in fluid communication with an environment outside of the MEMS device.

10. The apparatus according to claim 9, wherein the plurality of adhesive regions are conductive adhesive regions.

11. The apparatus according to claim 9, further comprising a second semiconductor die located between the support and the first semiconductor die, the second semiconductor die being electrically coupled to the first semiconductor die and including an integrated circuit.

12. The apparatus according to claim 11, further comprising conductive wires, wherein the second semiconductor is electrically coupled to the first semiconductor die by the conductive wires.

13. A process for manufacturing a MEMS device, the method comprising:

coupling a cap to a first face of a first semiconductor die, the cap facing the first face of the first semiconductor die, and enclosing a space between inner surfaces of the cap and a membrane formed in or on the first semiconductor die at the first face;

coupling a support to the first semiconductor die, the support facing a second face of the first semiconductor die, wherein the support has a first opening and the first semiconductor die has a plurality of second openings that provide a fluidic path from the enclosed space to an environment outside of the MEMS device; and

forming a packaging material enclosing outer surfaces of the cap and portions of the first semiconductor die.

14. The process according to claim 13, comprises forming a trench through the first semiconductor die that extends between the first and second faces that separates a suspended region from a peripheral region, the suspended region supporting the membrane and being coupled to the peripheral region by elastic elements that are located in the trench.

15. The process according to claim 13, further comprising forming a cavity in the first semiconductor die that extends from the second face under the membrane and thinning the first semiconductor die.

16. The process according to claim 13, wherein coupling the cap to the first face the first semiconductor die is carried out at wafer level and includes forming a composite wafer by coupling a first semiconductor wafer that includes the first semiconductor die to a second semiconductor wafer that includes the cap, the process further including dicing the composite wafer to form a plurality of MEMS device.

17. The process according to claim 13, further comprising forming the first through hole in the support prior to coupling the support to the semiconductor die.

18. The process according to claim 13, further comprising:

forming a second through hole in a second semiconductor die;

coupling the second semiconductor die to the support with the first and second through holes aligned or overlapping; and

wherein coupling the support to the first semiconductor die comprises coupling the second semiconductor die to the second face of the first semiconductor die, and wherein the second through hole is part of the fluidic path.