Flow sensor

Abstract

The flow sensor comprises a substrate assembly and a thin film assembly, the substrate assembly comprises a substrate, the substrate is provided with a cavity, the thin film assembly comprises a supporting layer and a sensitive layer, the supporting layer is arranged on one side of the substrate in the thickness direction and connected with the substrate, the supporting layer comprises a suspended area right facing the cavity, and the sensitive layer is arranged in the suspended area. The sensitive layer is arranged on one side, away from the substrate, of the supporting layer and is in contact with the suspended area, the substrate assembly further comprises a reinforcing structure, and the reinforcing structure is arranged in the cavity and is in contact with the other side of the suspended area. By arranging the reinforcing structure in the suspended area of the supporting layer, the strength of the thin film assembly is improved, residual stress and thermal stress of the thin film assembly are resisted, wrinkles and film breakage of the thin film assembly in the production and use process are prevented, the production yield is increased, and the service life is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of flow measurement, and in particular to a flow sensor. Background Art

[0002] A flow sensor is a sensor that converts flow / flow velocity signals into electrical signals. According to the technical route, it can be divided into thermal, electromagnetic, Coriolis, ultrasonic, etc. Among them, thermal flow sensors have become the most commercialized and widely used flow sensors because of their relatively easy and mature manufacturing process, wide range coverage, and low cost.

[0003] See also Figure 1 As shown, it is a thermal flow sensor in the prior art, which is mainly composed of a substrate assembly and a thin film assembly. The substrate assembly includes a substrate 11, and the substrate 11 is provided with a cavity 111. The thin film assembly includes a support layer 21 and a sensitive layer 22. The support layer 21 is arranged on one side of the substrate 11 in the thickness direction and connected to each other. The support layer 21 includes a suspended area 211 facing the cavity 111. The sensitive layer 22 is arranged on the side of the support layer 21 away from the substrate 11 and the sensitive layer 22 is in contact with the suspended area 211. The substrate 11 is generally made of silicon; a part of the substrate 11 The supporting layer 21 is generally composed of a nitride / oxide layer, which can be a single layer or a multi-layer composite structure; the sensitive layer 22 is generally composed of a material with a large temperature coefficient of resistance, such as Pt, Ni, polysilicon, Al, etc., and the substrate under the sensitive layer 22 is often removed to improve the sensitivity; in some flow sensors, there is also a protective layer 23 on the top layer, which is generally composed of a nitride / oxide layer, which can be a single layer or a multi-layer composite structure. This layer is not necessary and can be increased or decreased according to actual needs.

[0004] In the above thermal flow sensor, the support layer 21, the sensitive layer 22 and the protective layer 23 are thin film layers with a thickness between 10nm and 10um. Each thin film layer has residual stress and thermal stress. Figure 2 As shown in the figure, the deformation of the film component is about 2.75um. During the production and use process, the deformation of the film component may cause wrinkles and film breakage, which will affect the production yield and user use. Summary of the invention

[0005] To this end, the present invention provides a flow sensor, which aims to solve the problem that a thin film component of the flow sensor may have wrinkles and broken films during production and use.

[0006] In order to solve the above technical problems, the present invention provides a flow sensor, comprising:

[0007] A substrate assembly, the substrate assembly comprising a substrate, the substrate being provided with a cavity;

[0008] A thin film assembly, the thin film assembly comprising a support layer and a sensitive layer, the support layer being arranged on one side of the substrate in a thickness direction and connected to each other, the support layer comprising a suspended area facing the cavity, the sensitive layer being arranged on a side of the support layer away from the substrate and the sensitive layer being in contact with the suspended area;

[0009] The substrate assembly further includes a reinforcement structure disposed in the cavity and in contact with the other side of the suspended region.

[0010] Furthermore, a dimension of the reinforcement structure along the thickness direction of the substrate is L, and L<50um.

[0011] Furthermore, a groove is provided on a side of the reinforcement structure facing away from the support layer.

[0012] Furthermore, the substrate, the cavity and the reinforcement structure are formed by etching from the same substrate material.

[0013] Furthermore, the reinforcement structure is a regular shape or an irregular shape, and the reinforcement structure is a symmetrical structure or an asymmetrical structure.

[0014] Furthermore, the substrate is a silicon substrate.

[0015] Furthermore, the support layer is an oxide layer or a nitride layer.

[0016] Furthermore, the sensitive layer is a Pt layer, a Ni layer, a polysilicon layer or an Al layer.

[0017] Furthermore, the film assembly further comprises a protective layer, and the protective layer is arranged on a side of the sensitive layer away from the supporting layer.

[0018] Furthermore, the protective layer is a nitride layer or an oxide layer.

[0019] Furthermore, the protective layer is a nitride layer or an oxide layer.

[0020] The above technical solution of the present invention has the following advantages over the prior art: the flow sensor described in the present invention, by arranging a reinforcing structure in the suspended area of ​​the supporting layer, improves the strength of the thin film component, resists the residual stress and thermal stress of the thin film component, prevents wrinkles and breakage of the thin film component during production and use, and improves production yield and service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0022] Figure 1It is a front cross-sectional view of a flow sensor in the prior art;

[0023] Figure 2 It is a deformation simulation diagram of a thin film component in the prior art;

[0024] Figure 3 It is a bottom view of the flow sensor in the first embodiment of the present invention;

[0025] Figure 4 for Figure 3 Schematic diagram of the AA section;

[0026] Figure 5 This is a deformation simulation diagram of the film component in the first embodiment of the present invention;

[0027] Figure 6 Schematic diagram of the manufacturing process of the flow sensor in the first embodiment of the present invention;

[0028] Figure 7 It is a bottom view of the flow sensor in the second embodiment of the present invention;

[0029] Figure 8 for Figure 7 Schematic diagram of the AA section;

[0030] Fig. 9 It is a bottom view of the flow sensor in the third embodiment of the present invention;

[0031] Fig.10 for Fig. 9 Schematic diagram of the AA section;

[0032] Fig.11 It is a bottom view of the flow sensor in the fourth embodiment of the present invention;

[0033] Fig.12 for Fig.11 Schematic diagram of the AA section;

[0034] Fig.13 It is a bottom view of the flow sensor in the fifth embodiment of the present invention;

[0035] Fig.14 for Fig.13 Schematic diagram of the AA section;

[0036] Fig.15 It is a bottom view of the flow sensor in the sixth embodiment of the present invention;

[0037] Fig.16 for Fig.15 Schematic diagram of the AA section;

[0038] Fig.17 It is a bottom view of the flow sensor in the seventh embodiment of the present invention;

[0039] Fig.18 for Fig.17 Schematic diagram of the AA section;

[0040] Fig.19 It is a bottom view of the flow sensor in the eighth embodiment of the present invention;

[0041] Fig. 20 for Fig.19 Schematic diagram of the AA section;

[0042] Fig.21 It is a bottom view of the flow sensor in the ninth embodiment of the present invention;

[0043] Fig. 22 for Fig.21 Schematic diagram of the AA section;

[0044] Fig.23 It is a bottom view of the flow sensor in the tenth embodiment of the present invention;

[0045] Fig.24 for Fig.23 Schematic diagram of the AA section;

[0046] Fig.25 It is a bottom view of the flow sensor in the eleventh embodiment of the present invention;

[0047] Fig.26 for Fig.25 Schematic diagram of the AA section;

[0048] Fig. 27 It is a bottom view of the flow sensor in the twelfth embodiment of the present invention;

[0049] Fig.28 for Fig. 27 Schematic diagram of the AA section;

[0050] Fig.29 This is a schematic diagram of the manufacturing process of the flow sensor in the thirteenth embodiment of the present invention.

[0051] Description of the accompanying drawings:

[0052] 10. substrate material; 11. substrate; 111. cavity; 111a. first side cavity; 111b. first bottom cavity; 111c. second bottom cavity; 111d. second side cavity; 12. reinforcement structure; 121. groove;

[0053] 21. Support layer; 211. Suspended area; 22. Sensitive layer; 23. Protective layer. DETAILED DESCRIPTION

[0054] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0055] Embodiment 1

[0056] See also Figure 3 and Figure 4 FIG. 1 is an exemplary embodiment of a flow sensor according to the present invention.

[0057] The flow sensor comprises a substrate assembly and a thin film assembly, wherein the substrate assembly comprises a substrate 11, and the substrate 11 is provided with a cavity 111;

[0058] The thin film assembly includes a support layer 21 and a sensitive layer 22. The support layer 21 is disposed on one side of the substrate 11 in the thickness direction and connected to each other. The support layer 21 includes a suspended area 211 facing the cavity 111. The sensitive layer 22 is disposed on a side of the support layer 21 away from the substrate 11 and the sensitive layer 22 is in contact with the suspended area 211.

[0059] The substrate assembly further includes a reinforcing structure 12 . The reinforcing structure 12 is disposed in the cavity 111 and is in contact with the other side of the suspended region 211 .

[0060] The substrate 11 is used to support the entire flow sensor. The support layer 21 is used to support the sensitive layer 22 and to act as an insulator. The sensitive layer 22 is a temperature-sensitive thermistor material. Two sensitive layers 22 are arranged on the support layer 21, one of which is heated as a detection resistor, and the other is not heated as a reference resistor. When the medium flows, the heat on the detection resistor is taken away by the medium, and the resistance value is changed. The difference between the detection resistor and the reference resistor is used as the basis for judging the flow rate. The thickness of the support layer 21, the sensitive layer 22 and the protective layer 23 is usually between 10nm and 10um.

[0061] The above technical solution can resist the residual stress and thermal stress existing in the thin film component, improve the strength of the thin film component, prevent the thin film component from wrinkling and breaking during production and use, and improve the production yield and service life.

[0062] See also Figure 5 As shown, the deformation of the film assembly with the reinforcement structure 12 is about 1.26 um. Therefore, the reinforcement structure 12 has a certain resistance to the stress of the film assembly and can greatly reduce the deformation of the film assembly.

[0063] In a preferred implementation manner of this embodiment, a dimension of the reinforcement structure 12 along the thickness direction of the substrate 11 is L, and L<50 um.

[0064] The thickness of the reinforcing structure 12 should be less than 50um to reduce the heat loss of the sensitive layer 22 to the substrate 11. The thickness of the reinforcing structure 12 can be any value less than 50um, such as 48um, 46um, 44um, 42um, 40um, 38um, 36um, 34um, 32um, 30um, 28um, 26um, 24um, 22um or 20um.

[0065] In a preferred implementation manner of this embodiment, the substrate 11 , the cavity 111 , and the reinforcement structure 12 are formed by etching the same substrate material.

[0066] When the cavity 111 is corroded or etched on the substrate 11 , a portion of the substrate in contact with the film in the cavity 111 is left to form a reinforcement structure 12 .

[0067] In a preferred implementation manner of this embodiment, the reinforcement structure 12 and the substrate 11 are connected to each other.

[0068] The reinforcing structure 12 and the substrate 11 are connected to each other, and have better strength.

[0069] In the preferred implementation of this embodiment, the reinforcing structure 12 is in a regular symmetrical shape. In other embodiments, the reinforcing structure may also be in an irregular asymmetrical shape.

[0070] In a preferred implementation manner of the present embodiment, the reinforcing structure 12 has a cross section perpendicular to the thickness direction of the substrate 11 , and the cross section is in a straight line shape.

[0071] The reinforcing structure 12 has a rectangular cross section, and both ends of the rectangle are in contact with the substrate 11 respectively.

[0072] In the preferred implementation of this embodiment, the substrate 11 is a silicon substrate. Silicon substrate is the cheapest, largest available semiconductor material with mature device technology, and is suitable as a substrate for flow sensors.

[0073] In a preferred implementation manner of this embodiment, the support layer 21 is an oxide layer or a nitride layer.

[0074] The above-mentioned oxide layer and nitride layer oxide layer plays a protective role in the material and has an important influence on the stability, durability and application range of the material.

[0075] In a preferred implementation manner of this embodiment, the sensitive layer 22 is a Pt layer, a Ni layer, a polysilicon layer or an Al layer.

[0076] The materials having a relatively large resistance temperature coefficient, such as the Pt layer, the Ni layer, the polysilicon layer and the Al layer, are suitable for being used as detection resistors and reference resistors.

[0077] In a preferred implementation manner of the present embodiment, the flow sensor further comprises a protective layer 23 , and the protective layer 23 is disposed on a side of the sensitive layer 22 away from the supporting layer 21 .

[0078] The protective layer 23 is used to protect the sensitive layer 22 and play an insulating role.

[0079] In a preferred implementation manner of this embodiment, the protective layer 23 is a nitride layer or an oxide layer.

[0080] The above-mentioned oxide layer and nitride layer oxide layer plays a protective role in the material and has an important influence on the stability, durability and application range of the material.

[0081] See also Figure 6 As shown, the manufacturing process of the above flow sensor is as follows:

[0082] 1. Making a main structure, the main structure includes a substrate material 10, a support layer 21, a sensitive layer 22 and a protective layer 23 stacked in sequence;

[0083] 2. Determine the position, shape and size of the cavity 111 and the reinforcement structure 12, and divide the cavity 111 into a first side cavity 111a and a first bottom cavity 111b, wherein the first side cavity 111a is located on the side of the reinforcement structure 12 facing the substrate 11, and the first bottom cavity 111b is located on the bottom of the reinforcement structure 12 and the first side cavity away from the support layer 21;

[0084] 3. Corroding or etching the substrate material to form a first bottom cavity 111b;

[0085] 4. Corrode or etch the substrate material to form a first side cavity 111 a , and finally form a reinforcement structure 12 .

[0086] Embodiment 2

[0087] See also Figure 7 and Figure 8 FIG. 2 shows another embodiment of the flow sensor of the present invention.

[0088] The rest is the same as the first embodiment, except that the cross section of the reinforcement structure 12 is a cross.

[0089] The cross shape includes two rectangles that intersect each other vertically, and both ends of the rectangles are in contact with the substrate 11 respectively.

[0090] Embodiment 3

[0091] See also Fig. 9 and Fig.10 FIG. 2 shows another embodiment of the flow sensor of the present invention.

[0092] The rest is the same as the first embodiment, except that the cross section of the reinforcement structure is X-shaped.

[0093] The X-shape includes two rectangles intersecting to form an acute angle, and two ends of the rectangles are in contact with the substrate 11 respectively.

[0094] Embodiment 4

[0095] See also Fig.11 and Fig.12 FIG. 2 shows another embodiment of the flow sensor of the present invention.

[0096] The rest is the same as the first embodiment, except that the cross section of the reinforcement structure is in the shape of a letter "U".

[0097] The above-mentioned two-shaped shape includes two parallel rectangles, and both ends of the rectangles are in contact with the substrate 11 respectively.

[0098] Embodiment 5

[0099] See also Fig.13 and Fig.14 , the rest is the same as the first embodiment, except that the cross section of the reinforcement structure is an irregular shape.

[0100] Embodiment 6

[0101] See also Fig.15 and Fig.16 , another embodiment of the flow sensor in the present invention.

[0102] The rest is the same as the first embodiment, except that the reinforcing structure 12 is not connected to the substrate 11. The reinforcing structure 12 is not connected to the substrate 11 to reduce the heat loss of the sensitive layer 22 to the substrate 11 and reduce the overall power consumption of the flow sensor.

[0103] Embodiment 7

[0104] See also Fig.17 and Fig.18 , another embodiment of the flow sensor in the present invention.

[0105] The rest is the same as that of the sixth embodiment, except that the cross section of the reinforcement structure is a cross shape.

[0106] The cross shape includes two rectangles that intersect each other vertically, and both ends of the rectangles are not in contact with the substrate 11 .

[0107] Embodiment 8

[0108] See also Fig.19 and Fig. 20 FIG. 2 shows another embodiment of the flow sensor of the present invention.

[0109] The rest is the same as that of the sixth embodiment, except that the cross section of the reinforcement structure is X-shaped.

[0110] The X-shape includes two rectangles intersecting to form an acute angle, and both ends of the rectangles are not in contact with the substrate 11 .

[0111] Embodiment 9

[0112] See also Fig.21 and Fig. 22 FIG. 2 shows another embodiment of the flow sensor of the present invention.

[0113] The rest is the same as that of the sixth embodiment, except that the cross section of the reinforcement structure is in the shape of a letter "U".

[0114] The above-mentioned two-shaped shape includes two parallel rectangles, and both ends of the rectangles are not in contact with the substrate 11.

[0115] Embodiment 10

[0116] See also Fig.23 and Fig.24 FIG. 2 shows another embodiment of the flow sensor of the present invention.

[0117] The rest is the same as the sixth embodiment, except that the cross section of the reinforcement structure is an irregular shape.

[0118] Embodiment 11

[0119] See also Fig.25 and Fig.26 FIG. 2 shows another embodiment of the flow sensor of the present invention.

[0120] The rest is the same as the first embodiment, except that a groove 121 is provided on a side of the reinforcing structure 12 facing away from the supporting layer 21 .

[0121] The reinforcing structure 12 has a groove 121 inside, one end of the groove 121 passes through one end of the reinforcing structure 12 facing the supporting layer 21, and the other end of the groove 121 passes through one end of the reinforcing structure 12 facing away from the supporting layer 21, so as to further reduce the heat loss of the sensitive layer 22 to the substrate 11. The shape of the groove 121 can be a regular shape such as a square, rectangle, triangle, circle, etc., or it can be an irregular shape.

[0122] Embodiment 12

[0123] See also Fig. 27 and Fig.28 FIG. 2 shows another embodiment of the flow sensor of the present invention.

[0124] The rest is the same as that of the sixth embodiment, except that a groove 121 is provided on a side of the reinforcing structure 12 facing away from the supporting layer 21 .

[0125] The reinforcing structure 12 has a groove 121 inside, one end of the groove 121 passes through one end of the reinforcing structure 12 facing the supporting layer 21, and the other end of the groove 121 passes through one end of the reinforcing structure 12 facing away from the supporting layer 21, so as to further reduce the heat loss of the sensitive layer 22 to the substrate 11. The shape of the groove 121 can be a regular shape such as a square, rectangle, triangle, circle, etc., or it can be an irregular shape.

[0126] Embodiment 13

[0127] See also Fig.29 FIG. 2 shows another embodiment of the flow sensor of the present invention.

[0128] The rest is the same as any one of the embodiments 1 to 12, except that the manufacturing process of the flow sensor is as follows.

[0129] 1. Making a main structure, the main structure includes a substrate material 10, a support layer 21, a sensitive layer 22 and a protective layer 23 stacked in sequence;

[0130] 2. Determine the position, shape and size of the cavity 111 and the reinforcement structure 12, and divide the cavity 111 into a second bottom cavity 111c and a second side cavity 111d, wherein the second bottom cavity 111c is located at the bottom of the reinforcement structure 12 away from the support layer 21, and the second side cavity 111d is located at the side of the reinforcement structure 12 and the second bottom cavity 111c toward the substrate 11;

[0131] 3. Corroding or etching the substrate material to form a second bottom cavity 111c;

[0132] 4. Corrode or etch the substrate material to form a second side cavity 111 d , and finally form a reinforcement structure 12 .

[0133] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A flow sensor, comprising: A substrate assembly, the substrate assembly comprising a substrate, the substrate being provided with a cavity; A thin film assembly, the thin film assembly comprising a support layer and a sensitive layer, the support layer being arranged on one side of the substrate in a thickness direction and connected to each other, the support layer comprising a suspended area facing the cavity, the sensitive layer being arranged on a side of the support layer away from the substrate and the sensitive layer being in contact with the suspended area; It is characterized in that the substrate assembly further comprises a reinforcement structure, wherein the reinforcement structure is arranged in the cavity and the reinforcement structure is in contact with the other side of the suspended area.

2. The flow sensor according to claim 1, characterized in that: The dimension of the reinforcement structure along the thickness direction of the substrate is L, and L<50um.

3. The flow sensor according to claim 1, characterized in that: A groove is provided on a side of the reinforcement structure facing away from the support layer.

4. The flow sensor according to claim 1, characterized in that: The substrate, the cavity and the reinforcement structure are formed by etching the same substrate material.

5. The flow sensor according to claim 1, characterized in that: The reinforcement structure is of regular shape or irregular shape, and the reinforcement structure is of symmetrical structure or asymmetrical structure.

6. The flow sensor according to claim 1, characterized in that: The substrate is a silicon substrate.

7. The flow sensor according to claim 1, characterized in that: The support layer is an oxide layer or a nitride layer.

8. The flow sensor according to claim 1, characterized in that: The sensitive layer is a Pt layer, a Ni layer, a polysilicon layer or an Al layer.

9. The flow sensor according to claim 1, characterized in that: The film assembly further comprises a protective layer, and the protective layer is arranged on a side of the sensitive layer away from the supporting layer.

10. The flow sensor according to claim 9, characterized in that: The protective layer is a nitride layer or an oxide layer.

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