Pressure sensor with improved airtightness

Abstract

The sensor includes a substrate, an oxide layer, a membrane, an electrode, and a groove. The oxide layer is disposed on the substrate. The membrane is located on the oxide layer. The membrane, the oxide layer, and the substrate form a closed chamber therein. The membrane includes a rigid portion and a deformable portion, wherein the deformable portion of the membrane deforms in response to a stimulus. The oxide layer forms a sidewall of the chamber. The electrode is located on the substrate and in the chamber. The groove is formed in the oxide layer, and wherein the groove is covered with a barrier material.

Description

[0001] background

[0002] It is necessary to maintain chamber pressure for some sensors, such as pressure sensors. Unfortunately, due to the poor hermetic sealing of the pressure sensor weld interface, the pressure sensor will suffer from high-pressure error drift, such as exceeding 300Pa, which will cause gas effects over time. Gas effects can cause changes in chamber pressure, thereby causing error drift.

[0003] In some conventional systems, an oxide layer is used to reduce the gas effect. Although the use of an oxide layer improves hermicity, the gas effect still occurs. Summary of the invention

[0004] Therefore, there is a need to improve the airtight seal of the sensor. It should be understood that in some embodiments, a material with good airtightness (e.g., a metal or a high-density dielectric material, such as a nitride film) can be used as a barrier layer to improve the chamber airtight seal. In addition, a groove can be used to separate the core pressure chamber from the main oxide structural layer of the sensor. It should be understood that improving the airtight seal of the oxide interface can help to further reduce the gas effect. It is further understood that in some embodiments, the sidewalls of the chamber can also be coated with a barrier layer, such as a metal film or a nitride film, such as silicon nitride, etc., to further reduce the gas effect.

[0005] In some embodiments, the sensor includes a substrate, an oxide layer, a membrane, an electrode, and a groove. The oxide layer is disposed on the substrate. The membrane is located on the oxide layer. The membrane, the oxide layer, and the substrate form a closed chamber therein. The membrane includes a rigid portion and a deformable portion, wherein the deformable portion of the membrane deforms in response to a stimulus. The oxide layer forms a sidewall of the chamber. The electrode is located on the substrate and in the chamber. The groove is formed in the oxide layer, and wherein the groove is covered with a barrier material.

[0006] It is understood that in some embodiments, the groove surrounds the chamber. The groove can be located between the chamber and the periphery of the sensor. According to some embodiments, the groove extends into the rigid portion of the membrane. In some embodiments, the groove faces the external environment and away from the substrate. It is understood that the barrier material includes at least one of a silicon nitride layer or a metal layer.

[0007] In some embodiments, the sensor includes a substrate, an oxide layer, a membrane, an electrode, and a groove. The oxide layer can be disposed on the substrate. It should be understood that the membrane can be located on the oxide layer. According to some embodiments, the membrane, the oxide layer, and the substrate form a closed chamber therein. In some embodiments, the membrane includes a rigid portion and a deformable portion. The deformable portion deforms in response to a stimulus. The oxide layer forms the sidewalls of the chamber. The electrode is located on the substrate and in the chamber. The groove is formed in the oxide layer and is enclosed by the membrane and the substrate.

[0008] It should be understood that the sensor may also include a vent formed in the rigid portion of the membrane. In some embodiments, the groove and vent are aligned and connected to each other. It should be understood that in some embodiments, the vent is sealed with a cap and the cap is coated with a barrier material layer.

[0009] In some embodiments, the sensor includes a substrate, an oxide layer, a membrane, and an electrode. The oxide layer is disposed on the substrate. The membrane is located on the oxide layer. The membrane, the oxide layer, and the substrate form a closed chamber therein. The oxide layer includes an inner wall extending laterally from the membrane to the substrate and forming a side wall of the chamber. The oxide layer includes an outer wall extending laterally from the membrane to the substrate and away from the chamber. The membrane includes a rigid portion and a deformable portion, wherein the deformable portion deforms in response to a stimulus. The inner wall or the outer wall is coated with a barrier material layer. The electrode is located on the substrate and in the chamber.

[0010] It is understood that the barrier material layer comprises at least one of a silicon nitride layer or a metal layer. In some embodiments, the oxide layer is a high density plasma oxide layer. According to some embodiments, the top surface of the substrate is coated with another barrier material layer.

[0011] It will be appreciated that the sensor may also comprise a groove formed in the rigid portion of the membrane. It will be appreciated that the groove may be sealed by a cap. It will be appreciated that the groove may be coated with a layer of barrier material.

[0012] In some embodiments, the sensor may further include a groove formed in the oxide layer. The sensor may further include a vent formed in the rigid portion of the membrane. In some embodiments, the groove and the vent are aligned, and the vent is capped.

[0013]

[0011] These and other features and aspects of the concepts described herein will become better understood with regard to the following drawings, description, and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1A A sensor device having an isolation trench located at the periphery of a film coated with a barrier layer according to an aspect of the present embodiment is shown.

[0015] Figure 1BShown is an embodiment of the present invention according to one aspect Figure 1A Top view of the .

[0016] Figure 2A A sensor device according to an aspect of the present embodiment is shown, with a barrier layer coated on the chamber sidewall.

[0017] Figure 2B A sensor device according to one aspect of this embodiment is shown, and a lateral barrier layer is coated with an oxide layer, and the position of the lateral barrier layer is similar to Figure 2A different.

[0018] Figure 2C A sensor according to an aspect of this embodiment is shown with two lateral barrier layers coated with an oxide layer.

[0019] Figure 2D A sensor according to an aspect of the present embodiment is shown with the isolation trenches and the oxide layer coated with a barrier layer.

[0020] Figure 3A A sensor device according to one aspect of the present embodiment is shown having deep isolation trenches in the inner portion of the membrane.

[0021] Figure 3B A sensor device according to one aspect of the present embodiment is shown with deep isolation trenches in the inner part of the membrane and a lateral barrier coated with an oxide layer.

[0022] Figure 3C A sensor device according to one aspect of the present embodiment is shown with deep isolation trenches in the inner portion of the membrane and a lateral barrier layer positioned with respect to the Figure 3B different.

[0023] Figure 3D A sensor device according to an aspect of the present embodiment is shown with deep isolation trenches in the inner part of the membrane and two lateral barrier dielectric coated oxide layers.

[0024] Figure 3E yes Figure 3D Top view of the . DETAILED DESCRIPTION

[0025] Before describing various embodiments in more detail, it should be understood that the embodiments are not limited because the elements in the embodiments can be changed. It should also be understood that the specific embodiments described and / or shown herein have some elements that can be easily separated from the specific embodiments and can be optionally combined with any of several other embodiments or replace any of the elements in several other embodiments described herein.

[0026] It should also be understood that the terminology used herein is only for describing specific concepts and is not intended to be limiting. Unless otherwise defined, all technical and scientific terms used herein are consistent with the common understanding of the art to which the embodiments relate.

[0027] Unless otherwise specified, ordinal numbers (e.g., first, second, third, etc.) are used to distinguish or identify different elements or steps in a group of elements or steps, and do not provide an order or quantity limit for the elements or steps of their implementation. For example, "first", "second", and "third" elements or steps do not necessarily need to appear in this order, and their implementation does not necessarily need to be limited to three elements or steps. It should also be understood that, unless otherwise specified, any labels such as "left", "right", "front", "back", "top", "middle", "bottom", "beside", "forward", "reverse", "overlying", "under", "upper", "lower" or other similar terms (such as "upper", "lower", "above", "below", "below", "between", "above", "vertical", "horizontal / lateral", "proximal", "distal", "lateral", "formed", "composed", "reduced", "applied", "pulled", etc.) are used for convenience and are not intended to imply, for example, any specific fixed position, orientation or direction. Instead, these labels are used to reflect, for example, relative positions, orientations or directions. It should also be understood that the singular forms "a", "an", and "the" include plural meanings unless the context clearly indicates otherwise.

[0028] Terms such as "above," "overlapping," "above," "below," and the like should be understood to refer to elements that can be in direct contact or elements that can have other elements between them. For example, two layers can be in overlapping contact, where one layer is above the other layer and the two layers are in physical contact. In another example, two layers can be separated by one or more layers, where a first layer is above a second layer and one or more intermediate layers are between the first layer and the second layer, such that the first layer and the second layer are not in physical contact.

[0029] It should be understood that in some embodiments, the pressure sensor can be a monolithic device in which the MEMS layer is deposited on a silicon substrate. In some embodiments, the chamber can be formed in the MEMS substrate. It should be understood that part of the MEMS substrate can be removed so that the deformable membrane is formed by the silicon layer. The MEMS substrate is electrically connected to the circuit on the silicon substrate. It should be understood that the deformable membrane may be sensitive to stress in the pressure sensor. When the pressure sensor is mounted on a carrier and electrically connected to it, mechanical stress may be excited and transmitted to the MEMS substrate through the solder balls, in particular to the stress-sensitive structure of the pressure sensor, such as the deformable membrane. According to some embodiments, in the case of, the absolute pressure sensor with a deformable membrane has a partition between a chamber with a substantially constant pressure in the housing of the absolute pressure sensor and a port leading to the outside of the sensor.

[0030] It should be understood that in some embodiments, an oxide layer may be located between the substrate and the deformable membrane. However, to further reduce the gas effect, a barrier material (e.g., a nitride film, SiN x , or metal materials, etc.) as a barrier layer. For example, it should be understood that the lateral wall of the oxide layer between the substrate and the film can be coated with a barrier material to improve airtightness.

[0031] According to one embodiment, the core pressure chamber can be separated from the main oxide structural layer of the sensor using a groove located in the rigid part of the membrane. It will be appreciated that improving the hermetic sealing of the weld interface can help to further reduce the gas effect. It will also be appreciated that the isolation groove scheme can be combined with the use of a high density dielectric material that coats the walls of the oxide layer disposed between the deformable membrane and the substrate. Thus, the hermetic seal can be improved.

[0032] As used herein, the term "pressure sensor" refers to any type of sensor that measures a parameter equal to or derived from the pressure of a fluid. In particular, the term refers to relative (i.e., differential) pressure sensors and absolute pressure sensors, and it also includes static pressure sensors and dynamic pressure sensors. Typical application examples of such sensors are, for example: scientific instruments, meteorology, altimetry, recording, mobile or portable computers and telephones, etc. In the described embodiment, the gas effect refers to outgassing and leakage over a period of time.

[0033] Referring now to FIG. 1 , a sensor device according to one aspect of the present embodiment is shown, with isolation grooves in the periphery of a deformable membrane. The device shown includes a membrane 42 bonded (e.g., welded) to a substrate 2 (e.g., a silicon substrate) in which a chamber 41 is formed. The membrane has a rigid portion 42R and a deformable portion 42D. The deformable membrane 42D is located on the chamber and moves in response to an external stimulus or an internal drive. It should be understood that the chamber 41 can be formed by omitting or removing material from one or more layers. The chamber 41 is closed by the deformable membrane 42D. The deformable membrane 42D is thin enough to deform according to the pressure difference between the pressure at the top of the deformable membrane 42D and the pressure below it. The deformable membrane 42D is exposed to the environment to sense the pressure.

[0034] The substrate 2 may include a bulk material 23 (e.g., silicon) and a stack of oxide layers and metal layers on the bulk material 23. These layers may include circuits for electrical signal processing and may thus also be represented as CMOS layers. Specifically, for example, the layers may include multiple SiO2 layers, metal layers, or polysilicon layers, etc. The bulk material 23 may include doped regions in the silicon. These components may form active circuits, such as amplifiers, A / D converters, or other analog and / or digital signal processing units. The top layer of the layer stack may be silicon oxide and / or silicon nitride (e.g., SiN x ) to protect the structure below it. It should be understood that the dielectric barrier layer 122 (e.g., SiN x ) can also improve the airtightness of the chamber 41. In this example, the bulk silicon 23 oxide and the electrical processing circuit are collectively referred to as the substrate 2. The electrode 243 including the metal layer can be located on the top layer of the substrate 2, and it can be arranged at the bottom of the chamber 41 facing the deformable membrane 42D.

[0035] According to some embodiments, the membrane 42 may be formed of a doped conductive silicon layer, and it may be arranged as a sealing lid above the chamber 41. Thus, the deformable membrane 42D may be used as another electrode, which generates an electrical signal in response to an external stimulus (e.g., pressure). Thus, when the pressure changes, the deformable membrane 42D deflects, and thus the distance between the two electrodes changes, which results in a change in the capacitance between the two electrodes. In other words, in one embodiment, the sensing device may include the deformable membrane 42D itself as an electrode and thus include a conductive material. In addition, the electrode 243 (which is static) may be used as another electrode, and it may be arranged in the chamber 41 to allow sensing of the capacitance between the two electrodes, such as the capacitance between the electrode 243 and the deflectable membrane 42D. It will be understood that the capacitance depends on the distance between the electrodes. For example, in the case where a medium (e.g., air) is applied to the chamber 41 at a defined pressure and the deformable membrane 42D is caused to deflect, the distance between the electrodes may change and result in a change in the capacitance. In one embodiment, any electrode may be formed of a metal layer or a polysilicon layer.

[0036] The via 112 is coated with a conductive layer 101. The conductive layer 101 connects the circuit board (pat) 242 to the outside of the sensor. The electrical signal (e.g., the capacitance change between the deformable membrane 42D and the electrode 243) generated by the deformable membrane 42D in response to the pressure (e.g., the pressure change) is transmitted to the substrate 2. It should be understood that in some embodiments, the dielectric layer (e.g., the barrier layer) 102 can be coated with the conductive layer 101.

[0037] It should be understood that in some embodiments, there may be a dielectric material layer (e.g., an oxide layer) 104 sandwiched between the film 42 and the substrate 2. It should be understood that the oxide layer 104 may be a fused oxide or a high density plasma (HDP) layer, an HDP oxide, etc. In one example, the oxide layer 104 is located between the film 42 and the top surface of the substrate 2. In other words, the oxide layer 104 can form a sidewall of the chamber 41, which is also referred to as an inner wall. In other words, the oxide layer 104 can form a sidewall on the outside of the device, which is also referred to as an outer wall. In some embodiments, the top layer of the substrate 2 is coated with a different dielectric, for example, a barrier layer 122, thereby further improving the airtightness of the chamber in addition to protecting the lower layer of the substrate 2.

[0038] The isolation trench 103 is formed in the rigid film 42D. The isolation trench 103 is formed in the film 42 outside the chamber 41. In one embodiment, the isolation trench 103 extends into the oxide layer 104. In a non-limiting example, the isolation trench 103 extends from the rigid film 42D all the way through the oxide layer 104 and reaches the top layer of the substrate 2, for example, the barrier layer 122. The isolation trench 103 is also configured to improve the airtightness of the chamber 41.

[0039] In this embodiment, the isolation trench 103 is coated with a barrier material layer 105 to further help improve the airtightness of the chamber 41. It should be understood that in some embodiments, the isolation trench 103 can be covered (i.e., capped or sealed) with a metal material to further reduce the gassing effect. It should also be understood that the cover can also be coated with a barrier material layer. It should be understood that the isolation trench is located in the outer portion for illustrative purposes only and should not be interpreted as limiting the scope of the embodiment. For example, the isolation trench 103 can be located anywhere in the oxide layer 104 between the chamber 41 and the periphery of the device. It should be understood that in some embodiments, the isolation trench 103 can be sealed with a cap (e.g., metal).

[0040] Figure 1B Shows Figure 1A Top view of the .

[0041] Figure 2A A sensor device according to one aspect of the present embodiment is shown having a high density dielectric coating on the chamber sidewalls. Figure 2A Basically similar to Figure 1A , except that the barrier layer 204 improves the airtightness of the chamber 41. It should be understood that in some embodiments, the barrier layer 204 (e.g., SiN x ) may laterally cover the oxide layer 104 in the chamber 41. In other words, the oxide layer 104 forming the sidewall of the chamber 41 is covered with the barrier layer 204. In some embodiments, the barrier layer 204 may extend from the rigid film 42R to the top of the substrate 2, for example, the barrier layer 122, and laterally cover the oxide layer 104. It should be understood that the barrier layer 204 laterally covering the oxide layer 104 is for illustrative purposes only and should not be interpreted as limiting the scope of the embodiments. For example, in some embodiments, the barrier layer 204, while laterally covering the oxide layer 104, may not completely cover it. In other words, the barrier layer 204 may partially cover the lateral walls of the oxide layer 104 in the chamber 41. It should be understood that in some embodiments, the isolation trench 103 may be used in combination with covering the lateral walls of the oxide layer 104 with the barrier layer 204.

[0042] Reference now Figure 2B , which shows a sensor device according to one aspect of this embodiment, and the barrier layer is coated with an oxide layer, and the position of the barrier layer is Figure 2A different. Figure 2B Basically similar to Figure 2A, however, in this embodiment, the barrier layer 205 that laterally covers the oxide layer 104 is located on the outer wall of the oxide layer 104. Thus, the barrier layer 205 covers the lateral wall of the oxide layer 104 located on the periphery or perimeter of the oxide layer 104. The barrier layer 205 extends to the top surface of the substrate 2, such as the barrier layer 122. In some embodiments, the barrier layer 205 covers the outer sidewalls of the rigid film 42R.

[0043] Figure 2C A sensor according to one aspect of the present embodiment is shown with two barrier layers coated with an oxide layer. Figure 2C yes Figure 2A and Figure 2B In other words, barrier layer 204 covers the lateral walls of oxide layer 104 in chamber 41, and barrier layer 205 covers the lateral walls of oxide layer 104. In some embodiments, barrier layer 205 extends to the outer sidewalls of rigid film 42R. In some embodiments, isolation trench 103 (not shown in this example) can be used in combination with a barrier layer covering the sidewalls of oxide layer 104.

[0044] Figure 2D A sensor according to one aspect of the present embodiment is shown having deep trenches and two barrier layers coated with an oxide layer. Figure 2D yes Figure 1A , Figure 2A and Figure 2B The barrier layer 105 covering the isolation trench 103 improves the airtightness. The barrier layer 204 on the inner wall of the oxide layer and the barrier layer 205 on the outer wall of the oxide layer and the side wall of the rigid film further improve the airtightness of the chamber.

[0045] See now Figure 3A , shows a sensor device according to an aspect of the present embodiment, which has deep isolation trenches in the oxide layer 104. Figure 3A Basically similar to Figure 2A , except that the isolation trench 309 is formed in the oxide layer 104 between the chamber and the periphery. The isolation trench 309 is formed between the rigid film 42R and the substrate 2, which reaches the top surface of the substrate 2, such as the barrier layer 122. It should be understood that the isolation trench 309 can be located at any position in the oxide layer 104 adjacent to the chamber 41. In some embodiments, the isolation trench 309 is aligned with the exhaust hole 209. The exhaust hole 209 is a trench in the rigid film 42R. In some embodiments, the exhaust hole 209 is capped with a metal cap 23 and is also covered with a barrier layer 202.

[0046] Figure 3BA sensor device according to one aspect of the present embodiment is shown with deep isolation trenches in oxide layer 104 aligned with vent holes 209. In some embodiments, barrier layer 204 covers the lateral walls of oxide layer 104 in chamber 41 to further improve hermeticity.

[0047] Figure 3C A sensor device according to one aspect of the present embodiment is shown with deep isolation trenches in the oxide layer and a barrier layer on the periphery of the device and positioned with respect to Figure 3B In this embodiment, the barrier layer 205 covers the lateral walls of the oxide layer 104. In some embodiments, the barrier layer 205 covers the sidewalls of the rigid film. In some embodiments, the isolation trench 309 can be aligned with the vent hole 209.

[0048] Figure 3D A sensor device according to an aspect of the present embodiment is shown with a deep isolation trench in the oxide layer 104, two lateral barriers coating the oxide layer. Figure 3D The implementation method is Figure 3B and Figure 3C A combination of embodiments of the present invention comprises two dielectric layers, barrier layers 204 and 205, which cover the lateral walls of the oxide layer 104 in the chamber 41 and the periphery as well as the outer walls of the rigid membrane.

[0049] It should be understood that in some embodiments, the isolation trench 309 may extend into the rigid film 42R (similar to Figure 3B ). It will also be appreciated that the isolation trench 309 extending into the rigid film 42R may be sealed with a cap 203 (e.g., metal), and the cap may be covered with a barrier material layer 202. In some embodiments, the isolation trench 309 extending into the rigid film may be coated with a layer of barrier layer without a cap. It will be appreciated that the trenches 103 and / or 309 formed in the oxide layer may improve airtightness. Referring now to Figure 3E , showing Figure 3D Top view of the .

[0050] Although the embodiments have been described and / or shown by specific examples, and although these embodiments and / or examples have been described in great detail, the applicant has no intention of constraining or limiting the scope of the present invention in any way to such details. Additional adjustments and / or modifications of the embodiments may be apparent, and, in its broader aspects, the embodiments may include these adjustments and / or modifications. Therefore, without departing from the scope and spirit described herein, the above-mentioned embodiments and / or examples may be deviated from. The embodiments and other embodiments described above are within the scope of the appended claims.

Claims

1. A sensor comprising: Base material; an oxide layer disposed on a substrate; a membrane disposed on the oxide layer, wherein the membrane, the oxide layer and the substrate form an enclosed chamber therein, wherein the membrane includes a rigid portion and a deformable portion, wherein the deformable portion of the membrane deforms in response to a stimulus, and the oxide layer forms sidewalls of the chamber; electrodes on the substrate and within the chamber; and A trench is formed in the oxide layer, and wherein a gap separates a first wall of the trench from a second wall of the trench, wherein the first wall and the second wall of the trench are lined with a barrier material.

2. The sensor according to claim 1, wherein: A groove surrounds the chamber.

3. The sensor according to claim 1, wherein: The groove is located between the chamber and the periphery of the sensor.

4. The sensor according to claim 1, wherein: The grooves extend into the rigid portion of the membrane.

5. The sensor according to claim 4, wherein: The grooves face the external environment and away from the substrate.

6. The sensor according to claim 1, wherein: The barrier material includes at least one of a silicon nitride layer or a metal layer.

7. A sensor comprising: Base material; an oxide layer disposed on a substrate; a membrane on the oxide layer, wherein the membrane, the oxide layer, and the substrate form an enclosed chamber therein, wherein the membrane includes a rigid portion and a deformable portion, wherein the deformable portion deforms in response to a stimulus, and the oxide layer forms sidewalls of the chamber; electrodes on the substrate and within the chamber; and A trench is formed in the oxide layer and enclosed by the film and the substrate, wherein a gap separates a first wall of the trench from a second wall of the trench, wherein the first wall and the second wall of the trench are lined with a barrier material.

8. The sensor of claim 7, further comprising a vent formed in the rigid portion of the membrane.

9. The sensor according to claim 8, wherein: The grooves and the exhaust holes are aligned and connected to each other.

10. The sensor according to claim 8, wherein: The vent hole is sealed with a cap, and the cap is coated with a layer of barrier material.

11. A sensor comprising: Base material; an oxide layer disposed on a substrate; a membrane on the oxide layer, wherein the membrane, the oxide layer and the substrate form a closed chamber therein, wherein the oxide layer includes an inner wall extending laterally from the membrane to the substrate and forming a sidewall of the chamber, and the oxide layer includes an outer wall extending laterally from the membrane to the substrate facing away from the chamber, and the membrane includes a rigid portion and a deformable portion, wherein the deformable portion deforms in response to a stimulus, wherein the inner wall or the outer wall is coated with a barrier material layer; and Electrodes located on the substrate and within the chamber, The sensor further comprises a trench formed in the oxide layer, wherein a gap separates a first wall of the trench from a second wall of the trench, wherein the first wall and the second wall of the trench are lined with a barrier material.

12. The sensor according to claim 11, wherein The barrier material layer includes at least one of a silicon nitride layer or a metal layer.

13. The sensor according to claim 11, wherein: The oxide layer is a high density plasma oxide layer.

14. The sensor according to claim 11, wherein: The top surface of the substrate is coated with another layer of barrier material.

15. The sensor of claim 11, further comprising a groove formed in the rigid portion of the membrane.

16. The sensor of claim 15, wherein: The groove is sealed by a cap.

17. The sensor of claim 15, wherein: The grooves are coated with a layer of barrier material.

18. The sensor of claim 11 further comprising a vent formed in the rigid portion of the membrane.

19. The sensor of claim 18, wherein: The groove and the vent hole are aligned and the vent hole is capped.

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