Mouth-shaped heat source flow chip

Abstract

The utility model relates to a square heat source flow chip. The device comprises a substrate, and the back surface of the substrate is provided with a back surface release cavity. The supporting structure layer is arranged on the substrate; the first insulating layer is arranged on the supporting structure layer; the upstream temperature measuring element thermopiles, the central heat source and the downstream temperature measuring element thermopiles are respectively arranged on the first insulating layer, the central heat source is of a square structure, and the multiple groups of upstream temperature measuring element thermopiles and the multiple groups of downstream temperature measuring element thermopiles are respectively distributed side by side along the longitudinal direction of the chip; front release isolation through holes are formed between the adjacent upstream temperature measurement element thermopiles and between the adjacent downstream temperature measurement element thermopiles, and the front release isolation through holes extend to the back release cavity. According to the utility model, the sensitivity of the temperature measuring element to heat is improved and the power consumption of the chip is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of flow sensors, in particular to a square-shaped heat source flow chip. Background Art

[0002] Thermal flow sensor is a device that uses thermal sensing effect for measurement, and is suitable for measuring the flow of gas and liquid. Its main components include hot wire sensor, compensation circuit, temperature compensation circuit and operational amplifier. Due to its advantages of high accuracy, fast response speed and no influence from medium, it is widely used in industrial automation, air conditioning, automobile industry, medical equipment, robots and other fields.

[0003] Existing flow chips have high power consumption, which not only increases the cost of use, but also limits their application in certain scenarios where power is limited or low power consumption is required. In addition, flow chips have certain limitations in measurement accuracy and resolution, which affects their use in some high-precision applications. Summary of the invention

[0004] To this end, the utility model provides a square-shaped heat source flow chip, which improves the sensitivity of the temperature measuring element to heat and reduces the power consumption of the chip.

[0005] In order to solve the above technical problems, the utility model provides a square-shaped heat source flow chip, comprising:

[0006] A substrate, wherein a back side release cavity is provided on the back side of the substrate;

[0007] A supporting structure layer is disposed on the substrate;

[0008] A first insulating layer, disposed on the supporting structure layer;

[0009] The upstream temperature measuring element thermopile, the central heat source and the downstream temperature measuring element thermopile are respectively arranged on the first insulating layer, wherein a plurality of groups of the upstream temperature measuring element thermopile and a plurality of groups of the downstream temperature measuring element thermopile are respectively arranged side by side along the longitudinal direction of the chip, and the central heat source is in a "mouth" shaped structure;

[0010] Among them, there are front release isolation through holes between adjacent upstream temperature measuring element thermoelectric piles and between adjacent downstream temperature measuring element thermoelectric piles, and the front release isolation through holes extend to the back release cavity.

[0011] In one embodiment of the present invention, the upstream temperature measuring element thermopile, the central heat source and the downstream temperature measuring element thermopile are covered with a passivation layer.

[0012] In one implementation of the present utility model, the front release isolation through hole is an inverted cone structure.

[0013] In one implementation of the utility model, the back release cavity is a trapezoidal structure.

[0014] In one embodiment of the utility model, the upstream temperature measuring element thermopile comprises an upstream temperature measuring element thermopile lower layer thermocouple and an upstream temperature measuring element thermopile upper layer thermocouple;

[0015] The downstream temperature measuring element thermopile comprises a downstream temperature measuring element thermopile lower layer thermocouple and a downstream temperature measuring element thermopile upper layer thermocouple;

[0016] The upstream temperature measuring element thermopile lower layer thermocouple and the downstream temperature measuring element thermopile lower layer thermocouple are covered with a second insulating layer;

[0017] The upper thermocouple of the upstream temperature measuring element thermopile and the upper thermocouple of the downstream temperature measuring element thermopile are covered with a third insulating layer.

[0018] In one embodiment of the utility model, it also includes a connecting wire structure that runs through the third insulating layer;

[0019] The connecting wire structure includes an upstream cold end connecting wire connected to the lower thermocouple of the upstream temperature measuring element thermopile, an upstream hot end connecting wire connected between the lower thermocouple of the upstream temperature measuring element thermopile and the upper thermocouple of the upstream temperature measuring element thermopile, a downstream cold end connecting wire connected to the lower thermocouple of the downstream temperature measuring element thermopile, a downstream hot end connecting wire connected between the lower thermocouple of the downstream temperature measuring element thermopile and the upper thermocouple of the downstream temperature measuring element thermopile, and a central heat source wire connected to the central heat source.

[0020] In one embodiment of the present invention, the upstream temperature measuring element thermopile and the downstream temperature measuring element thermopile are symmetrically arranged along the longitudinal symmetrical section of the chip.

[0021] In one embodiment of the utility model, the upstream temperature measuring element thermopile in each of the thermopile temperature measuring elements leads out an upstream temperature measuring element positive electrode and an upstream temperature measuring element negative electrode; the downstream temperature measuring element thermopile in each of the thermopile temperature measuring elements leads out a downstream temperature measuring element positive electrode and a downstream temperature measuring element negative electrode; the central heat source leads out a heating element wire positive electrode and a heating element wire negative electrode.

[0022] In one embodiment of the utility model, the supporting structure layer includes a first silicon oxide supporting layer, a silicon nitride supporting layer and a second silicon oxide supporting layer sequentially arranged on the surface of the substrate, a passivation layer is arranged on the surface of the third insulating layer, and the front release isolation through hole sequentially penetrates the passivation layer, the third insulating layer, the second insulating layer, the first insulating layer, the second silicon oxide supporting layer, the silicon nitride supporting layer and the first silicon oxide supporting layer.

[0023] The above technical solution of the utility model has the following advantages compared with the prior art:

[0024] The utility model discloses a "mouth"-shaped heat source flow chip, which forms an isolation through hole in the insulation layer between the adjacent thermocouple pairs of the temperature measuring elements by setting the front release isolation through hole and the back release cavity, thereby isolating the back heat transfer channel and improving the sensitivity of the temperature measuring element to heat. This allows the central heat source to be driven by only a very small voltage, and the temperature measuring element can sense the heat change, thereby improving the overall resolution of the chip and reducing the chip power consumption; and the central heat source is in a "mouth"-shaped structure, which can further reduce the heat source resistance and power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the content of the utility model more clearly understood, the utility model is further described in detail below based on specific embodiments of the utility model in combination with the accompanying drawings.

[0026] Figure 1 It is a schematic diagram of the chip structure from a top view of the utility model.

[0027] Figure 2 yes Figure 1 Schematic diagram of the sectional view of the XX` axial section.

[0028] Figure 3 yes Figure 1 Schematic diagram of the cross-sectional view of the YY` axial section (part).

[0029] Figure 4 It is a schematic diagram of three groups of thermopile temperature measuring elements of the utility model.

[0030] Figure 5 It is a schematic diagram of a thermopile temperature measuring element of the utility model.

[0031] Description of the Figures in the Specification:

[0032] 1. Substrate;

[0033] 2. A first silicon oxide support layer;

[0034] 3. Silicon nitride support layer;

[0035] 4. A second silicon oxide support layer;

[0036] 5a, the thermocouple of the lower layer of the thermopile of the upstream temperature measuring element; 5b, the thermocouple of the lower layer of the thermopile of the downstream temperature measuring element;

[0037] 6. Central heat source;

[0038] 7a, a first insulating layer; 7b, a second insulating layer; 7c, a third insulating layer;

[0039] 8a, upper thermocouple of the thermopile of the upstream temperature measuring element; 8b, upper thermocouple of the thermopile of the downstream temperature measuring element;

[0040] 91. Upstream cold end connecting wire; 92. Upstream hot end connecting wire; 93. Central heat source wire; 94. Downstream cold end connecting wire; 95. Downstream hot end connecting wire;

[0041] 10. Passivation layer;

[0042] 11. Front release isolation through hole;

[0043] 12. Back release cavity;

[0044] 13a, positive electrode of upstream temperature measuring element; 13b, negative electrode of upstream temperature measuring element;

[0045] 14a, positive electrode of downstream temperature measuring element; 14b, negative electrode of downstream temperature measuring element;

[0046] 15a, positive electrode of the heating element wire; 15b, negative electrode of the heating element wire. DETAILED DESCRIPTION

[0047] The present invention will be 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.

[0048] Reference Figures 1 to 3 As shown, a square-shaped heat source flow chip of the utility model comprises:

[0049] A substrate 1, wherein a back side release cavity 12 is provided on the back side of the substrate 1;

[0050] A supporting structure layer, disposed on the substrate 1;

[0051] A first insulating layer 7a, disposed on the supporting structure layer;

[0052] The upstream temperature measuring element thermopile, the central heat source 6 and the downstream temperature measuring element thermopile are respectively arranged on the first insulating layer 7a, wherein a plurality of groups of the upstream temperature measuring element thermopile and a plurality of groups of the downstream temperature measuring element thermopile are respectively arranged side by side along the longitudinal direction of the chip;

[0053] Among them, there are front release isolation through holes 11 between adjacent upstream temperature measuring element thermoelectric piles and between adjacent downstream temperature measuring element thermoelectric piles, and the front release isolation through holes 11 extend to the back release cavity 12.

[0054] In this embodiment, the central heat source 6 is in a "mouth"-shaped structure, which can reduce the heat source resistance and power consumption.

[0055] Specifically, the upstream temperature measuring element thermopile, the central heat source 6 and the downstream temperature measuring element thermopile are covered with a passivation layer 10 .

[0056] Specifically, the front release isolation through hole 11 is in an inverted cone structure; the back release cavity 12 is in a trapezoidal structure. Since the back of the substrate 1 is anisotropically dry-etched to form an inverted trapezoid, and the front is wet-etched, the aspect ratio can be made relatively large, but the front release isolation through hole 11 is small, so the deeper it is, the more difficult it is to etch, and finally an inverted cone structure is formed.

[0057] Specifically, the upstream temperature measuring element thermopile includes an upstream temperature measuring element thermopile lower layer thermocouple 5a and an upstream temperature measuring element thermopile upper layer thermocouple 8a;

[0058] The downstream temperature measuring element thermopile comprises a downstream temperature measuring element thermopile lower layer thermocouple 5b and a downstream temperature measuring element thermopile upper layer thermocouple 8b;

[0059] The upstream temperature measuring element thermopile lower layer thermocouple 5a and the downstream temperature measuring element thermopile lower layer thermocouple 5b are covered with a second insulating layer 7b;

[0060] The upper thermocouple 8a of the upstream temperature measuring element thermopile and the upper thermocouple 8b of the downstream temperature measuring element thermopile are covered with a third insulating layer 7c;

[0061] The first to third insulating layers 7c are all made of silicon oxide.

[0062] Specifically, it also includes a connecting wire structure that penetrates the third insulating layer 7c;

[0063] The connecting wire structure includes an upstream cold end connecting wire 91 connected to the lower thermocouple 5a of the upstream temperature measuring element thermopile, an upstream hot end connecting wire 92 connected between the lower thermocouple 5a of the upstream temperature measuring element thermopile and the upper thermocouple 8a of the upstream temperature measuring element thermopile, a downstream cold end connecting wire 94 connected to the lower thermocouple 5b of the downstream temperature measuring element thermopile, a downstream hot end connecting wire 95 connected between the lower thermocouple 5b of the downstream temperature measuring element thermopile and the upper thermocouple 8b of the downstream temperature measuring element thermopile, and a central heat source wire 93 connected to the central heat source 6.

[0064] Specifically, the upstream temperature measuring element thermopile and the downstream temperature measuring element thermopile are symmetrically arranged along a longitudinal symmetrical section of the chip.

[0065] Specifically, the support structure layer includes a first silicon oxide support layer 2, a silicon nitride support layer 3 and a second silicon oxide support layer 4 which are sequentially arranged on the surface of the substrate 1.

[0066] Specifically, a passivation layer 10 is disposed on the surface of the third insulating layer 7c to enhance the overall anti-pollution capability of the chip; wherein the passivation layer 10 is made of silicon nitride.

[0067] Specifically, the front release isolation through hole 11 sequentially penetrates the passivation layer 10, the third insulating layer 7c, the second insulating layer 7b, the first insulating layer 7a, the second silicon oxide support layer 4, the silicon nitride support layer 3 and the first silicon oxide support layer 2.

[0068] In this embodiment, multiple groups of upstream temperature measuring element thermopiles and multiple groups of downstream temperature measuring element thermopiles are respectively distributed side by side along the longitudinal direction of the chip; the corresponding upstream temperature measuring element thermopiles and downstream temperature measuring element thermopiles are symmetrically arranged along the longitudinal symmetrical section of the chip.

[0069] In this embodiment, refer to Figure 4 , Figure 5 As shown, three groups of thermopile temperature measuring elements are included and are symmetrically distributed along the transverse (XX' axis) symmetrical section of the chip. Each group of thermopile temperature measuring elements includes four rows of upstream temperature measuring element thermopiles and corresponding four rows of downstream temperature measuring element thermopiles. In each group of thermopile temperature measuring elements, two adjacent groups of upstream temperature measuring element thermopiles and two adjacent groups of downstream temperature measuring element thermopiles are connected by wires.

[0070] The upstream temperature measuring element thermopile in each thermopile temperature measuring element leads out the upstream temperature measuring element positive electrode 13a and the upstream temperature measuring element negative electrode 13b; the downstream temperature measuring element thermopile in each thermopile temperature measuring element leads out the downstream temperature measuring element positive electrode 14a and the downstream temperature measuring element negative electrode 14b; the central heat source 6 leads out the heating element wire positive electrode 15a and the heating element wire negative electrode 15b.

[0071] After the temperature measuring element senses the temperature, it will transfer heat from the hot end to the cold end, forming the Seebeck effect and generating a thermoelectric potential between the hot and cold ends. That is, this part of heat conduction is necessary and is also one of the important factors that determine the sensitivity of the chip, because the greater the temperature difference between the hot and cold ends, the greater the thermoelectric potential, the greater the output signal, and the greater the sensitivity of the chip. However, in addition to transferring heat to the cold end, the hot end will also transfer heat to the left and right adjacent thermocouples and the lower insulating support layer. By preparing the front isolation release hole, the hot end can be prevented from transferring heat to the left and right adjacent thermocouples. At the same time, in conjunction with the back release cavity 12, the lower insulating support layer between each group of thermocouples of the thermopile temperature measuring element is directly completely carved open, thereby blocking the heat transfer channel from the hot end to the bottom insulating support layer. Therefore, after the direction of the unnecessary heat transfer channel is reduced, when the hot end conducts heat, there is only one heat transfer channel, which is to flow to the cold end, so the thermoelectric potential between the hot and cold ends will be higher, and the chip sensitivity will also be higher.

[0072] In summary, by bidirectional release etching on the front and back sides, the insulating layer between the adjacent thermocouple pairs of the temperature measuring element is formed into an isolation through hole, thereby isolating the back heat transfer channel and improving the sensitivity of the temperature measuring element to heat. This allows the central heat source 6 to be driven by only a very small voltage, and the temperature measuring element can sense the heat change, thereby improving the overall resolution of the chip and reducing the chip power consumption.

[0073] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to examples, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A square-shaped heat source flow chip, characterized in that: include: A substrate (1), a back side of which is provided with a back side release cavity (12); A supporting structure layer, arranged on the substrate (1); A first insulating layer (7a) is arranged on the supporting structure layer; The upstream temperature measuring element thermopile, the central heat source (6) and the downstream temperature measuring element thermopile are respectively arranged on the first insulating layer (7a), wherein a plurality of groups of the upstream temperature measuring element thermopile and a plurality of groups of the downstream temperature measuring element thermopile are respectively arranged side by side along the longitudinal direction of the chip, and the central heat source (6) is in a "mouth"-shaped structure; Wherein, the front release isolation through holes (11) between adjacent upstream temperature measuring element thermoelectric piles and between adjacent downstream temperature measuring element thermoelectric piles extend to the back release cavity (12).

2. The square-shaped heat source flow chip according to claim 1, characterized in that: The upstream temperature measuring element thermopile, the central heat source (6) and the downstream temperature measuring element thermopile are covered with a passivation layer (10).

3. The square heat source flow chip according to claim 1, characterized in that: The front release isolation through hole (11) is in an inverted cone structure.

4. The square heat source flow chip according to claim 1, characterized in that: The back release cavity (12) has a trapezoidal structure.

5. The square-shaped heat source flow chip according to claim 1, characterized in that: The upstream temperature measuring element thermopile comprises an upstream temperature measuring element thermopile lower layer thermocouple (5a) and an upstream temperature measuring element thermopile upper layer thermocouple (8a); The downstream temperature measuring element thermopile comprises a downstream temperature measuring element thermopile lower layer thermocouple (5b) and a downstream temperature measuring element thermopile upper layer thermocouple (8b); The upstream temperature measuring element thermopile lower layer thermocouple (5a) and the downstream temperature measuring element thermopile lower layer thermocouple (5b) are covered with a second insulating layer (7b); The upper thermocouple (8a) of the upstream temperature measuring element thermopile and the upper thermocouple (8b) of the downstream temperature measuring element thermopile are covered with a third insulating layer (7c).

6. The square-shaped heat source flow chip according to claim 5, characterized in that: It also includes a connecting wire structure that passes through the third insulating layer (7c); The connecting wire structure comprises an upstream cold end connecting wire (91) connected to the lower thermocouple (5a) of the upstream temperature measuring element thermopile, an upstream hot end connecting wire (92) connected between the lower thermocouple (5a) of the upstream temperature measuring element thermopile and the upper thermocouple (8a) of the upstream temperature measuring element thermopile, a downstream cold end connecting wire (94) connected to the lower thermocouple (5b) of the downstream temperature measuring element thermopile, a downstream hot end connecting wire (95) connected between the lower thermocouple (5b) of the downstream temperature measuring element thermopile and the upper thermocouple (8b) of the downstream temperature measuring element thermopile, and a central heat source wire (93) connected to the central heat source (6).

7. The square-shaped heat source flow chip according to claim 1, characterized in that: The upstream temperature measuring element thermopile and the downstream temperature measuring element thermopile are symmetrically arranged along the longitudinal symmetric section of the chip.

8. The square-shaped heat source flow chip according to claim 1, characterized in that: It comprises three groups of thermopile temperature measuring elements, and is symmetrically distributed along the transverse symmetrical section of the chip, each group of thermopile temperature measuring elements comprises four rows of upstream temperature measuring element thermopiles and corresponding four rows of downstream temperature measuring element thermopiles, and in each group of thermopile temperature measuring elements, two adjacent groups of upstream temperature measuring element thermopiles and two adjacent groups of downstream temperature measuring element thermopiles are connected by wires.

9. The square-shaped heat source flow chip according to claim 8, characterized in that: The upstream temperature measuring element thermopile in each of the thermopile temperature measuring elements leads out an upstream temperature measuring element positive electrode (13a) and an upstream temperature measuring element negative electrode (13b); the downstream temperature measuring element thermopile in each of the thermopile temperature measuring elements leads out a downstream temperature measuring element positive electrode (14a) and a downstream temperature measuring element negative electrode (14b); and the central heat source (6) leads out a heating element wire positive electrode (15a) and a heating element wire negative electrode (15b).

10. The square-shaped heat source flow chip according to claim 5, characterized in that: The support structure layer comprises a first silicon oxide support layer (2), a silicon nitride support layer (3) and a second silicon oxide support layer (4) which are sequentially arranged on the surface of the substrate (1); a passivation layer (10) is arranged on the surface of the third insulating layer (7c); and the front release isolation through hole (11) sequentially penetrates the passivation layer (10), the third insulating layer (7c), the second insulating layer (7b), the first insulating layer (7a), the second silicon oxide support layer (4), the silicon nitride support layer (3) and the first silicon oxide support layer (2).

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