Pressure sensor chip and manufacturing method thereof

Abstract

A pressure sensor chip comprises a substrate, a temperature sensitive resistor and a pressure sensitive resistor, the pressure sensor chip is provided with a cavity, at least part of the substrate is located on the periphery of the cavity, the temperature sensitive resistor and the pressure sensitive resistor are both connected with the substrate, and at least part of the temperature sensitive resistor is located in the cavity. According to the pressure sensor chip, at least part of the temperature sensitive resistor is located in the cavity, the influence of the external environment on the resistance value of the temperature sensitive resistor is reduced, and the temperature detection precision of the temperature sensitive resistor is improved. The invention provides a manufacturing method of a pressure sensor chip, and the method comprises the following steps: carrying out the etching and ion doping of a silicon layer, and forming a temperature sensitive resistor; etching the first insulating layer to form a groove; and at least part of the temperature sensitive resistor is arranged in the groove, and the first insulating layer and the silicon layer are connected, so that at least part of the groove forms a cavity.

Description

Technical Field

[0001] This application relates to the technical field of sensors, and particularly to a pressure sensor chip and a manufacturing method thereof. Background Art

[0002] The pressure sensor chip integrates a temperature-sensitive resistor, enabling the pressure sensor chip to detect temperature while detecting pressure. In related technologies, the resistance value of the temperature-sensitive resistor is affected not only by the temperature of the fluid to be measured but also by the external environment. The external environment affects the detection accuracy of the temperature-sensitive resistor. Summary of the Invention

[0003] To this end, this application provides a pressure sensor chip, including a substrate, a temperature-sensitive resistor, and a pressure-sensitive resistor. The pressure sensor chip has a cavity, at least part of the substrate is located outside the cavity, both the temperature-sensitive resistor and the pressure-sensitive resistor are connected to the substrate, and at least part of the temperature-sensitive resistor is located in the cavity.

[0004] In the pressure sensor chip of this application, at least part of the temperature-sensitive resistor is located in the cavity, reducing the influence of the external environment on the resistance value of the temperature-sensitive resistor and improving the temperature detection accuracy of the temperature-sensitive resistor.

[0005] This application provides a manufacturing method of a pressure sensor chip, including the following steps:

[0006] Etch and ion dope a silicon layer to form a temperature-sensitive resistor;

[0007] Etch a first insulating layer to form a groove;

[0008] Place at least part of the temperature-sensitive resistor in the groove, and connect the first insulating layer and the silicon layer so that at least part of the groove forms a cavity.

[0009] In the manufacturing method provided by this application, at least part of the temperature-sensitive resistor is located in the cavity formed by the groove, reducing the influence of the external environment on the resistance value of the temperature-sensitive resistor and improving the temperature detection accuracy of the temperature-sensitive resistor. Brief Description of the Drawings

[0010] Figure 1 It is a schematic cross-sectional view of a pressure sensor chip provided by an embodiment of this application;

[0011] Figure 2 It is a cross-sectional view before doping and etching of the silicon layer, used to show the sensitive area;

[0012] Figure 3 It is a schematic diagram of the positions of the pressure-sensitive resistor and the temperature-sensitive resistor provided by an embodiment of this application. Detailed Description of the Embodiments

[0013] Exemplary embodiments will be described in detail herein, and examples thereof are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application.

[0014] The pressure sensor chip of the exemplary embodiment of the present application will be described in detail below with reference to the accompanying drawings.

[0015] Currently, the pressure sensor chip integrates a temperature-sensitive resistor, enabling the pressure sensor chip to detect temperature while detecting pressure. During the detection process, the resistance value of the temperature-sensitive resistor is converted to obtain the temperature of the measured fluid (such as refrigerant). Ideally, the resistance value of the temperature-sensitive resistor is only affected by the temperature of the measured fluid. However, in reality, the resistance value of the temperature-sensitive resistor is also affected by the external environment, thereby affecting the detection accuracy of the temperature-sensitive resistor.

[0016] Therefore, the pressure sensor chip in the present application includes a substrate 2, a temperature-sensitive resistor 1, and a pressure-sensitive resistor 3. The pressure sensor chip has a cavity 4, and at least a part of the substrate 2 is located outside the cavity 4. Both the temperature-sensitive resistor 1 and the pressure-sensitive resistor 3 are connected to the substrate 2, and the temperature-sensitive resistor 1 is at least partially located in the cavity 4. When there is refrigerant leakage, the heat of the refrigerant can be quickly transferred to the cavity 4 through the substrate 2. The cavity 4 can serve as a heat-insulating place, and the heat of the refrigerant will not quickly dissipate in the cavity 4. The temperature-sensitive resistor 1 can sensitively and accurately detect the change in the refrigerant temperature in the environment, improving the detection accuracy of the pressure sensor chip.

[0017] In one embodiment, the pressure sensor chip can detect pressure and temperature simultaneously. As Figure 1 shown, the substrate 2 includes a pressure-sensitive film 21, and at least a part of the pressure-sensitive film 21 is located outside the cavity 4. The pressure-sensitive resistor 3 is connected to the pressure-sensitive film 21. In one embodiment, for example, the pressure-sensitive resistor 3 is located within the substrate 2; or, the pressure-sensitive resistor 3 is located in the cavity 4, that is, both the pressure-sensitive resistor 3 and the temperature-sensitive resistor 1 are located in the cavity 4. Further, the cavity 4 is a vacuum cavity. Define the plane perpendicular to the thickness direction H of the pressure sensing chip as the projection plane. The orthographic projection of the pressure-sensitive film 21 on the projection plane is the first projection, and the orthographic projection of the temperature-sensitive resistor 1 on the projection plane is the second projection. The second projection is located outside the first projection. Specifically, the temperature-sensitive resistor 1 will not contact the pressure-sensitive film 21 to avoid mutual influence and thus reduce the detection accuracy.

[0018] In order to reduce the influence of the heat generated when the piezoresistor 3 works on the temperature-sensitive resistor 1, in one embodiment, perpendicular to the thickness direction H of the pressure sensor chip, the distance between the temperature-sensitive resistor 1 and the piezoresistor 3 is greater than or equal to 600 um. At the same time, in order to control the volume of the pressure sensor chip, in one embodiment, the distance between the temperature-sensitive resistor 1 and the piezoresistor 3 is less than or equal to 1 mm, so that the volume of the pressure sensor chip will not be too large.

[0019] The pressure sensor chip includes four piezoresistors 3. The four piezoresistors 3 are electrically connected to form a Wheatstone bridge. During detection, the pressure-sensitive film 21 deforms, causing the resistance values of the four piezoresistors 3 to change. The magnitude of the pressure is measured by the change in current. Further, the pressure sensor chip further includes four second conductive resistors 32 and four third conductive parts 33. The second conductive resistor 32 is electrically connected to the third conductive part 33, and the piezoresistor 3 is electrically connected to the third conductive part 33. That is, the electrical connection between the second conductive resistor 32 and the piezoresistor 3 is through the third conductive part 33. The type of the formed Wheatstone bridge can be a full bridge, a half bridge, or a quarter bridge. The pressure sensor chip includes a fourth conductive part 34 and a second solder ball 51. The second solder ball 51 can output a pressure signal. The fourth conductive part 34 is electrically connected to the second solder ball 51, and the fourth conductive part 34 is electrically connected to the second conductive resistor 32.

[0020] In one embodiment, as Figure 3 shown, the temperature-sensitive resistor 1 is located outside the region 31 surrounded by the four piezoresistors 3. Further, the distance between the piezoresistors 3 directly adjacent to the temperature-sensitive resistor 1 is greater than or equal to 600 um and less than or equal to 1 mm.

[0021] The pressure sensor chip includes a first conductive resistor 11. In order to reduce costs and improve the adaptability of the electrical connection with the first conductive resistor 11, it is preferred to use the first conductive resistor 11 instead of a wire. The temperature-sensitive resistor 1 is electrically connected to the first conductive resistor 11, and the first conductive resistor 11 is connected to the substrate 2. In order to reduce the heat generated by the first conductive resistor 11 during use from being directly transmitted to the temperature-sensitive resistor 1, in one embodiment, there is a gap between the first conductive resistor 11 and the temperature-sensitive resistor 1. Further, the pressure sensor chip includes a first conductive part 12, and at least a part of the first conductive part 12 is located in the gap.

[0022] To output a temperature signal, the pressure sensor chip includes a second conductive portion 13 and a first solder ball 5. The first conductive portion 12 is electrically connected to the temperature-sensitive resistor 1, and the first conductive portion 12 is electrically connected to the first conductive resistor 11. The second conductive portion 13 is electrically connected to the first solder ball 5, and the second conductive portion 13 is electrically connected to the first conductive resistor 11. Along the thickness direction H of the pressure sensor chip, the first conductive resistor 11 and the first solder ball 5 are located at both ends of the second conductive portion 13. After the temperature-sensitive resistor 1 senses a temperature change, it transmits current to the first conductive resistor 11 through the first conductive portion 12, and then leads out the current through the second conductive portion 13, and outputs a signal through the first solder ball 5.

[0023] Since the second conductive portion 13 and the fourth conductive portion 34 are used to lead out signals, the second conductive portion 13 and the fourth conductive portion 34 are preferably made of thick conductive materials. In one embodiment, the second conductive portion 13 includes copper. In one embodiment, the fourth conductive portion 34 includes a metal layer, and the metal layer includes one or more of platinum, copper, and nickel. Further, the second conductive portion 13 and the fourth conductive portion 34 include a platinum metal layer. To reduce costs, in one embodiment, the first conductive portion 12 includes aluminum, and the third conductive portion 33 includes aluminum.

[0024] In one embodiment, the pressure sensor chip includes a first insulating layer 61, the first insulating layer 61 is silicon dioxide, the substrate 2 and the pressure-sensitive film 21 are made of silicon or silicon carbide. Further, the substrate 2 is N-type silicon, and the temperature-sensitive resistor 1, the pressure-sensitive resistor 3, and the first conductive resistor 11 are made of P-type silicon.

[0025] The pressure sensor chip further includes a second insulating layer 62. Along the thickness direction H of the pressure sensor chip, the second insulating layer 62 is located between the temperature-sensitive resistor 1 and the substrate 2. Specifically, the second insulating layer 62 is silicon dioxide, and the second insulating layer 62 is bonded to the substrate 2.

[0026] The first insulating layer 61 has a first hole 611, the first hole 611 penetrates through the first insulating layer 61, and the first hole 611 is at least partially aligned with the first conductive resistor 11. Further, the first hole 611 is filled with dry film or silicon dioxide, and at least a part of the second conductive portion 13 is located in the first hole 611. Along the thickness direction H of the pressure sensor chip, a part of the second conductive portion 13 and the first conductive resistor 11 are respectively located on both sides of the first insulating layer 61.

[0027] A manufacturing method of a pressure sensor chip includes the following steps:

[0028] Etch and ion dope the silicon layer 14 to form the temperature-sensitive resistor 1;

[0029] Etch the first insulating layer 61 to form a groove 612;

[0030] Place at least a part of the temperature-sensitive resistor 1 in the groove 612, and connect the first insulating layer 61 to the silicon layer 14, so that at least a part of the groove 612 forms a cavity 4.

[0031] In the manufacturing method provided by this application, at least a part of the temperature-sensitive resistor 1 is located in the cavity 4 formed by the groove 612, reducing the influence of the external environment on the resistance value of the temperature-sensitive resistor 1 and improving the temperature detection accuracy of the temperature-sensitive resistor 1.

[0032] In some embodiments, the ion doping is boron ion doping. In some embodiments, the groove 612 is recessed from the first insulating layer 61 towards one end of the substrate 2 into the interior of the first insulating layer 61. In some embodiments, the first insulating layer 61 is silicon dioxide, and the first insulating layer 61 is connected to the silicon layer 14 by anodic bonding.

[0033] Specifically, in some embodiments, the manufacturing method of the pressure sensor chip includes the following steps:

[0034] S1. Etch the silicon layer 14 to form a temperature-sensitive region 141;

[0035] S2. Perform ion doping on the temperature-sensitive region 141 to form a temperature-sensitive resistor 1;

[0036] S3. Etch the first insulating layer 61 to form a groove 612;

[0037] S4. Place at least a part of the temperature-sensitive resistor 1 in the groove 612, and connect the first insulating layer 61 to the silicon layer 14, so that at least a part of the groove 612 forms a cavity 4.

[0038] In some embodiments, step S2 can be performed before step S1. Specifically, the manufacturing method of the pressure sensor chip includes the following steps:

[0039] S1'. Perform ion doping on the temperature-sensitive region 141 on the silicon layer 14;

[0040] S2'. Etch the silicon layer 14 to form a temperature-sensitive resistor 1 in the temperature-sensitive region 141;

[0041] S3. Etch the first insulating layer 61 to form a groove 612;

[0042] S4. Place at least a part of the temperature-sensitive resistor 1 in the groove 612, and connect the first insulating layer 61 to the silicon layer 14, so that at least a part of the groove 612 forms a cavity 4.

[0043] In some embodiments, step S1 further includes: etching the silicon layer 14 to form a pressure-sensitive region 143. Step S2 further includes: ion-doping the pressure-sensitive region 143 to form a pressure-sensitive resistor 3.

[0044] In some embodiments, the silicon layer 14 is etched to form a resistor region 142; the resistor region 142 is ion-doped to form a first conductive resistor 11 and a second conductive resistor 32. According to the different concentrations of boron ion doping, the one with a lower concentration forms the pressure-sensitive resistor 3, and the ones with a higher concentration form the first conductive resistor 11 and the second conductive resistor 32. Step S4 further includes: placing at least a part of the pressure-sensitive region in the groove 612.

[0045] In some embodiments, step S1 further includes: ion-doping the pressure-sensitive region 143 and the resistor region 142 on the silicon layer 14.

[0046] In one embodiment, a method for manufacturing a pressure sensor chip includes the following steps:

[0047] Providing a substrate 2;

[0048] Laying a second insulating layer 62 on the surface of the substrate 2; in some embodiments, the second insulating layer 62 is made of silicon dioxide and is connected to the substrate 2 by anodic bonding.

[0049] Laying the silicon layer 14 on the surface of the second insulating layer 62.

[0050] Along the thickness direction of the chip, the silicon layer 14 and the substrate 2 are respectively located on both sides of the second insulating layer 62.

[0051] Further, in one embodiment, a method for manufacturing a pressure sensor chip includes the following steps: etching the first insulating layer 61 to form a first hole 611, filling a dry film in the first hole 611, providing a second conductive part 13, etching the outer wall of the first hole 611, and attaching the second conductive part 13 to the outer wall of the first hole 611, and the second conductive part 13 is electrically connected to the first conductive resistor 11;

[0052] Providing a first solder ball 5 and a second solder ball 51, the first solder ball 5 is connected to the second conductive part 53, specifically, the first solder ball 5 and the second conductive part 53 are connected to each other by a reflow soldering technique, and the fourth conductive part 34 is electrically connected to the second solder ball 51, specifically, the fourth conductive part 34 and the second solder ball 51 are connected to each other by a reflow soldering technique.

[0053] The above are only the preferred embodiments of the present application, and do not impose any form of limitation on the present application. Although the present application has been disclosed above with the preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to equivalent embodiments of equivalent changes within the scope of the technical solution of the present application by using the above-disclosed technical content. However, as long as it does not depart from the technical solution of the present application, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application still fall within the scope of the technical solution of the present application.

Claims

1. A pressure sensor chip, characterized in that, it includes a substrate, a temperature-sensitive resistor, and a pressure-sensitive resistor. The pressure sensor chip has a cavity, and at least part of the substrate is located outside the cavity. Both the temperature-sensitive resistor and the pressure-sensitive resistor are connected to the substrate, and at least part of the temperature-sensitive resistor is located in the cavity.

2. The pressure sensor chip according to claim 1, characterized in that: The substrate includes a pressure-sensitive film, at least part of the pressure-sensitive film is located outside the cavity, and the pressure-sensitive resistor is connected to the pressure-sensitive film; Define the plane perpendicular to the thickness direction of the pressure sensing chip as the projection plane. The orthographic projection of the pressure-sensitive film on the projection plane is the first projection, and the orthographic projection of the temperature-sensitive resistor on the projection plane is the second projection. The second projection is located outside the first projection.

3. The pressure sensor chip according to claim 2, characterized in that: The pressure-sensitive resistor is located in the cavity.

4. The pressure sensor chip according to claim 2, characterized in that: The distance between the temperature-sensitive resistor and the pressure-sensitive resistor is greater than or equal to 600um and less than or equal to 1mm.

5. The pressure sensor chip according to claim 2, characterized in that: The pressure sensor chip includes four pressure-sensitive resistors, and the temperature-sensitive resistor is located outside the area surrounded by the four pressure-sensitive resistors.

6. The pressure sensor chip according to claim 1, characterized in that: The pressure sensor chip includes a first conductive resistor. The temperature-sensitive resistor is electrically connected to the first conductive resistor. The first conductive resistor is connected to the substrate, and there is a gap between the first conductive resistor and the temperature-sensitive resistor.

7. The pressure sensor chip according to claim 6, characterized in that: The pressure sensor chip includes a first conductive part, a second conductive part, and a first solder ball. The first conductive part is electrically connected to the temperature-sensitive resistor and the first conductive resistor, and at least part of the first conductive part is located in the gap; The second conductive part is electrically connected to the first solder ball and the first conductive resistor. Along the thickness direction of the pressure sensor chip, the first conductive resistor and the first solder ball are located at both ends of the second conductive part.

8. The pressure sensor chip according to claim 7, characterized in that: The first conductive part includes aluminum, the second conductive part includes copper, and the cavity is a vacuum cavity.

9. The pressure sensor chip according to claim 7, characterized in that: The pressure sensor chip includes a first insulating layer. The first insulating layer has a first hole that penetrates the first insulating layer. At least part of the second conductive part is located in the first hole. Along the thickness direction of the pressure sensor chip, a part of the second conductive part and the first conductive resistor are located on both sides of the first insulating layer.

10. A manufacturing method of a pressure sensor chip, characterized in that, it includes the following steps: Etch and ion dope the silicon layer to form a temperature-sensitive resistor; Etch the first insulating layer to form a groove; Place at least part of the temperature-sensitive resistor in the groove and connect the first insulating layer to the silicon layer so that at least part of the groove forms a cavity.

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