Pressure sensor generating a transduced signal with reduced ambient temperature dependence, and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-10809140-B2
Application number	US-201514980373-A
Country	US
Kind code	B2
Filing date	Dec 28, 2015
Priority date	Jun 22, 2015
Publication date	Oct 20, 2020
Grant date	Oct 20, 2020

Abstract

A pressure sensor designed to detect a value of ambient pressure of the environment external to the pressure sensor includes: a first substrate having a buried cavity and a membrane suspended over the buried cavity; a second substrate having a recess, hermetically coupled to the first substrate so that the recess defines a sealed cavity the internal pressure value of which provides a pressure-reference value; and a channel formed at least in part in the first substrate and configured to arrange the buried cavity in communication with the environment external to the pressure sensor. The membrane undergoes deflection as a function of a difference of pressure between the pressure-reference value in the sealed cavity and the ambient-pressure value in the buried cavity.

First claim

The invention claimed is:

1. A pressure sensor configured to detect a value of ambient pressure of an environment external to the pressure sensor, comprising:
a first semiconductor body having an inner buried cavity and a membrane suspended over the buried cavity, a first surface of the membrane defining a top of the buried cavity;
a second semiconductor body different from the first semiconductor body and having a recess, the second semiconductor body being hermetically coupled to the first semiconductor body in such a way that the recess faces a second surface of the membrane opposite to the first surface, thus defining a sealed cavity having an internal pressure value that provides a pressure-reference value; and
a channel formed at least in part in the first semiconductor body and configured to set the buried cavity in fluidic communication with the environment external to the pressure sensor,
the membrane being configured to undergo deflection as a function of a pressure difference between the pressure-reference value in the sealed cavity and a pressure value in the buried cavity.

2. The pressure sensor according to claim 1 , wherein the membrane houses a transducer assembly configured to generate a transduced electrical signal as a function of the deflection of the membrane, the transducer assembly being arranged in a surface portion of the membrane facing inside of the sealed cavity.

3. The pressure sensor according to claim 1 , wherein the channel extends as partial prolongation of the buried cavity in a same plane as the buried cavity, reaching a side wall, orthogonal to the plane, of the first semiconductor body.

4. The pressure sensor according to claim 1 , wherein the channel extends as partial prolongation of the buried cavity, in part along a first direction belonging to a plane of the buried cavity and in part along a second direction orthogonal to the first direction, reaching a side of the first semiconductor body exposed to the external environment.

5. The pressure sensor according to claim 4 , further comprising:
a coupling region that completely surrounds the membrane, the first semiconductor body and second semiconductor body being hermetically coupled together via the coupling region, wherein the channel extends along the second direction in a portion of the first semiconductor body external to the coupling region.

6. The pressure sensor according to claim 1 , wherein:
the channel extends in the first semiconductor body as partial prolongation of the buried cavity, in part along a first direction belonging to a plane of the buried cavity and in part along a second direction orthogonal to the first direction, reaching a side of the first semiconductor body facing the second semiconductor body, and
the channel further extends completely through the second semiconductor body, the buried cavity being in fluidic communication with the external environment through the channel in the second semiconductor body.

7. The pressure sensor according to claim 6 , further comprising:
a coupling region that completely surrounds the membrane, the first and second semiconductor bodies being hermetically coupled together via the coupling region, wherein the channel further extends in the second direction through the coupling region.

8. The pressure sensor according to claim 1 , comprising a getter layer housed in the recess and configured to reduce, when activated, the pressure value inside the sealed cavity.

9. The pressure sensor according to claim 1 , further comprising:
a coupling region that hermetically couples the first and second semiconductor bodies together and defines a portion of the sealed cavity between the first and second semiconductor bodies.

10. A pressure sensor configured to detect a value of ambient pressure of an environment external to the pressure sensor, comprising:
a substrate having an inner buried cavity and a membrane suspended over the buried cavity;
a cap hermetically coupled to the substrate and defining a sealed cavity between the cap and the substrate, the sealed cavity having an internal pressure value that provides a pressure-reference value and at least partially overlaps the inner buried cavity; and
a channel formed at least in part in the substrate and configured to set the buried cavity in fluidic communication with the environment external to the pressure sensor,
the membrane being configured to undergo deflection as a function of a pressure difference between the pressure-reference value in the sealed cavity and a pressure value in the buried cavity.

11. The pressure sensor according to claim 10 , wherein the membrane houses a transducer assembly configured to generate a transduced electrical signal as a function of the deflection of the membrane, the transducer assembly being arranged in a surface portion of the membrane.

12. The pressure sensor according to claim 10 , further comprising:
a coupling region that completely surrounds the membrane, the substrate and cap being hermetically coupled together via the coupling region, wherein the channel extends along a second direction in a portion of the substrate external to the coupling region.

13. The pressure sensor according to claim 10 , wherein:
the channel extends in the substrate as partial prolongation of the buried cavity, in part along a first direction belonging to a plane of the buried cavity and in part along a second direction orthogonal to the first direction, reaching a side of the substrate facing the cap, and
the channel further extends completely through the cap, the buried cavity being in fluidic communication with the external environment through the channel in the cap.

14. The pressure sensor according to claim 13 , further comprising:
a coupling region that completely surrounds the membrane, the substrate and cap being hermetically coupled together via the coupling region, wherein the channel further extends in the second direction through the coupling region.

15. The pressure sensor according to claim 10 , further comprising:
a coupling region that hermetically couples the substrate and the cap together and defines a portion of the sealed cavity between the substrate and the cap.

16. A pressure sensor configured to detect a value of ambient pressure of an environment external to the pressure sensor, comprising:
a semiconductor body having an inner buried cavity and a membrane suspended over the buried cavity;
a sealed cavity that faces the membrane and at least partially overlaps the buried cavity; and
a channel formed in the semiconductor body and configured to set the buried cavity in fluidic communication with the environment external to the pressure sensor, wherein the membrane is configured to undergo deflection as a function of a pressure difference between a pressure-reference value in the sealed cavity and a pressure value in the buried cavity.

17. The pressure sensor according to claim 16 , wherein the membrane houses a transducer assembly configured to generate a transduced electrical signal as a function of the deflection of the membrane, the transducer assembly being arranged in a surface portion of the membrane facing inside of the sealed cavity.

18. The pressure sensor according to claim 16 , wherein the channel extends as partial prolongation of the buried cavity in a same plane as the buried cavity, reaching a side wall, orthogonal to the plane, of the semiconductor body.

19. The pressure sensor according to claim 16 , wherein the channel extends as partial prolongation of the buried

Assignees

• St Microelectronics Srl

Inventors

• Duqi Enri
• Conti Sebastiano
• Costantini Sonia

Classifications

• B81B2201/0264

  Pressure sensors · CPC title

• B81B7/0061

  suitable for fluid transfer from the MEMS out of the package or vice versa, e.g. transfer of liquid, gas, sound · CPC title

• B81C2201/0116

  Thermal treatment for structural rearrangement of substrate atoms, e.g. for making buried cavities · CPC title

• B81B2203/0127

  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 title

• B81C2201/0133

  Wet etching · CPC title