A micromachined self-heating effect free temperature sensor

Abstract

The application discloses a micromachined temperature sensor without self-heating effect, which comprises a semiconductor substrate, an insulating medium layer, a multilayer film cantilever structure and a wire bonding area. The multilayer film cantilever structure is composed of a metal film, a P+ type semiconductor film and a P type semiconductor film from top to bottom, and comprises two mutually symmetrical arc-shaped cantilever beams, each of which is connected by a long-axis cantilever beam and a short-axis cantilever beam, and the two ends are fixed and led out through the wire bonding area. The two arc-shaped cantilever beams form a parallel plate capacitor, which constitutes a temperature sensitive capacitor of the sensor. When the temperature changes, the deformation amounts of the long-axis cantilever beam and the short-axis cantilever beam are different, so that the cantilever beam deflects in the horizontal plane, and because the two cantilever beams are arranged in a symmetrical layout, the two cantilever beams move in opposite directions, and finally cause the change of the parallel plate capacitor. At the same time, because the capacitor does not have direct current power consumption, and only an alternating current small signal needs to be used during measurement, the sensor is not affected by the self-heating effect, and has high precision.

Description

TECHNICAL FIELD

[0001] The present application relates to a micromachined temperature sensor, in particular to a micromachined temperature sensor without self-heating effect. BACKGROUND

[0002] Temperature is closely related to people's daily life, and the research on temperature measurement and temperature sensor has a very long history. There are many types of temperature sensors available at present, and the temperature measurement principles are also various. The development history of temperature sensors is roughly from traditional discrete temperature sensors to intelligent integrated temperature sensors. Traditional temperature sensors have their own irreplaceable advantages, but their large size and poor consistency still restrict their application in portable devices and microelectronic products.

[0003] With the development and progress of micromachining technology, the advantages of semiconductor temperature sensors such as small size, small heat capacity and fast response are realized. The temperature measurement principles of most traditional temperature sensors can be applied to semiconductor integrated temperature sensors. Common semiconductor temperature sensors include platinum resistance type, thermistor type, thermocouple type, PN junction type, etc. With the development of MEMS (Micro Electro Mechanical System) technology, piezoresistive, resonant, polysilicon micro-bridge and bimetallic cantilever beam type MEMS temperature sensors have been continuously developed. Most of the existing temperature sensors use resistance or current as the sensitive output, and the biggest disadvantage of these sensors is high power consumption, and their self-heating effect will affect temperature measurement. SUMMARY

[0004] The present application provides a micromachined temperature sensor without self-heating effect, which can avoid the interference of self-heating effect on temperature measurement and improve the precision.

[0005] Technical scheme: A micromachined temperature sensor without self-heating effect, comprising a semiconductor substrate, an insulating medium layer arranged on the surface of the semiconductor substrate, a first multilayer film cantilever beam structure, a second multilayer film cantilever beam structure, a first wire bonding area, and a second wire bonding area.

[0006] The first multilayer film cantilever beam structure comprises a metal thin film, a P+ type semiconductor thin film and a P type semiconductor thin film arranged from top to bottom, one end of the first multilayer film cantilever beam structure is connected with the first wire bonding area to form a wire fixed end, the other end of the first multilayer film cantilever beam structure is connected with the insulating medium layer to form a wire fixed end, and the first multilayer film cantilever beam structure forms a gap with the semiconductor substrate in the vertical direction.

[0007] The second multilayer film cantilever structure includes a metal film and a semiconductor film, one end of the second multilayer film cantilever structure is connected with the second wire bonding area to form a wire fixed end, the other end of the second multilayer film cantilever structure is connected with the insulating medium layer to form a wire fixed end, and a gap is formed between the second multilayer film cantilever structure and the semiconductor substrate in the vertical direction; the first multilayer film cantilever structure and the second multilayer film cantilever structure are kept in the same horizontal plane.

[0008] Further, the first multilayer film cantilever structure is an arc structure composed of a long-axis cantilever and a short-axis cantilever, and the second multilayer film cantilever structure is an arc structure composed of a long-axis cantilever and a short-axis cantilever.

[0009] Further, the semiconductor substrate is a silicon substrate.

[0010] Further, the insulating medium layer is a silicon dioxide medium layer.

[0011] Further, the metal film is a gold film.

[0012] Further, the P+ type semiconductor film is a P+ type heavily doped silicon film.

[0013] Further, the P type semiconductor film is a P type monocrystalline silicon film.

[0014] Advantages: Compared with the prior art, the present application has the following advantages:

[0015] 1. The temperature sensor structure of the present application forms a changeable parallel plate capacitor. The multilayer film cantilever structure is composed of two mutually symmetrical arc-shaped cantilevers, each of which is composed of a long-axis cantilever and a short-axis cantilever, and the two ends are fixed and led out through a wire bonding area. The two mutually symmetrical arc-shaped cantilevers form a parallel plate capacitor, which constitutes the temperature-sensitive capacitor of the temperature sensor of the present application. When the temperature changes, the deformation amounts of the long axis and the short axis in the arc-shaped cantilever are different, so that the arc-shaped cantilever deflects in the horizontal plane. Because the two arc-shaped cantilevers are arranged symmetrically in the horizontal plane, the two arc-shaped cantilevers will move in opposite directions, finally causing the change of the parallel plate capacitor. Therefore, compared with the traditional capacitive micromechanical temperature sensor, the temperature-sensitive capacitor is large, so the precision of the sensor is high.

[0016] 2. The temperature sensor of the present application uses a capacitor as a sensitive element for temperature measurement. Since the capacitor does not have direct current power consumption, and only an alternating current small signal is needed when the capacitor is measured, the sensor is not affected by self-heating effect. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a plan view of the present application;

[0018] Figure 2 is a sectional view of the present application along A-A'. DETAILED DESCRIPTION

[0019] The present application will be further explained in conjunction with the accompanying drawings.

[0020] As shown in Figure 1 , Figure 2 , a micromachined temperature sensor without self-heating effect comprises a semiconductor substrate 1, an insulating medium layer 2 arranged on the surface of the substrate, a first multilayer film cantilever structure 3, a second multilayer film cantilever structure 4, a first wire bonding area 5, and a second wire bonding area 6. The first multilayer film cantilever structure 3 is composed of a metal thin film 13, a P+ type semiconductor thin film 14, and a P type semiconductor thin film 15 from top to bottom. One end of the first multilayer film cantilever structure 3 is connected with the first wire bonding area 5 to form a wire fixed end. The other end of the first multilayer film cantilever structure 3 is connected with the insulating medium layer 2 to form a fixed end 7. The first multilayer film cantilever structure 3 forms a gap with the semiconductor substrate 1 in the vertical direction. The second multilayer film cantilever structure 4 is composed of a metal thin film 13, a P+ type semiconductor thin film 14, and a P type semiconductor thin film 15 from top to bottom. One end of the second multilayer film cantilever structure 4 is connected with the second wire bonding area 6 to form a wire fixed end. The other end of the second multilayer film cantilever structure 4 is connected with the insulating medium layer 2 to form a fixed end 8. The second multilayer film cantilever structure 4 forms a gap with the semiconductor substrate 1 in the vertical direction. The first multilayer film cantilever structure 3 and the second multilayer film cantilever structure 4 are located in the same horizontal plane.

[0021] The first multilayer film cantilever structure 3 is an arc structure composed of a long-axis cantilever beam 9 and a short-axis cantilever beam 10. The second multilayer film cantilever structure 4 is an arc structure composed of a long-axis cantilever beam 11 and a short-axis cantilever beam 12. The semiconductor substrate 1 is a silicon substrate. The insulating medium layer 2 is a silicon dioxide medium layer. The metal thin film 13 is a gold thin film. The P+ type semiconductor thin film 14 is a P+ type heavily doped silicon thin film. The P type semiconductor thin film 15 is a P type single crystal silicon thin film.

[0022] The micromachined temperature sensor without self-heating effect can be prepared by the following process:

[0023] a: heavily doped to form a P+ layer on the surface of an SOI (silicon on insulator) wafer;

[0024] b: deposit a metal layer and perform photoetching;

[0025] c: Deep reactive ion etching with the metal layer as a mask, etching silicon to the oxide layer;

[0026] d: Etching to remove the oxide layer, releasing the structure.

[0027] The working principle of the micromachined self-heating effect free temperature sensor is as follows: the multilayer film cantilever structure is composed of two mutually symmetrical first multilayer film cantilever structures 3 and second multilayer film cantilever structures 4, and each arc-shaped cantilever is composed of a long-axis cantilever and a short-axis cantilever. The two mutually symmetrical arc-shaped cantilevers form a parallel plate capacitor, which constitutes the temperature sensitive capacitor of the temperature sensor. When the temperature changes, the deformation amounts of the long-axis and short-axis in the arc-shaped cantilever are different due to the heating, so that the arc-shaped cantilever deflects in the horizontal plane. Because the two arc-shaped cantilevers are arranged in a symmetrical layout in the horizontal plane, the two arc-shaped cantilevers will move in opposite directions, finally causing the change of the parallel plate capacitor.

[0028] The working process of the micromachined self-heating effect free temperature sensor is as follows: when the ambient temperature rises, the length of the long-axis cantilever 9 in the first multilayer film cantilever structure 3 increases more than that of the short-axis cantilever 10, so that the long-axis cantilever 9 deflects to the short-axis cantilever 10 in the horizontal plane. At the same time, the long-axis cantilever 11 in the second multilayer film cantilever structure 4 also deflects to the short-axis cantilever 12, so that the gap between the first multilayer film cantilever structure 3 and the second multilayer film cantilever structure 4 becomes larger, finally making the parallel plate capacitor increase, that is, the temperature sensitive capacitor will increase; when the ambient temperature decreases, the length of the long-axis cantilever 9 in the first multilayer film cantilever structure 3 decreases more than that of the short-axis cantilever 10, so that the short-axis cantilever 10 deflects to the long-axis cantilever 9 in the horizontal plane. At the same time, the short-axis cantilever 12 in the second multilayer film cantilever structure 4 also deflects to the long-axis cantilever 11, so that the gap between the first multilayer film cantilever structure 3 and the second multilayer film cantilever structure 4 becomes smaller, finally making the parallel plate capacitor decrease, that is, the temperature sensitive capacitor will decrease.

[0029] Before using the micromachined self-heating effect free temperature sensor, first, use standard equipment to calibrate the temperature sensor, and establish the corresponding relationship between the temperature value and the capacitance value. When measuring, the output capacitance value of the temperature sensor is monitored, and the calibration value is compared, so that the measured temperature value can be obtained.

[0030] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements can be made, and these improvements should also be considered as the protection scope of the present application.

Claims

1. A micro-machined temperature sensor without self-heating effect, characterized in that: Includes a semiconductor substrate (1), an insulating dielectric layer (2) disposed on the surface of the semiconductor substrate (1), a first multilayer cantilever beam structure (3), a second multilayer cantilever beam structure (4), a first wire bonding region (5), and a second wire bonding region (6): The first multilayer film cantilever beam structure (3) includes a metal thin film (13), a P+ type semiconductor thin film (14) and a P type semiconductor thin film (15) arranged from top to bottom. One end of the first multilayer film cantilever beam structure (3) is connected to the first lead bonding region (5) to form a lead fixing end. The other end of the first multilayer film cantilever beam structure (3) is connected to the insulating dielectric layer (2) to form a lead fixing end (7). The first multilayer film cantilever beam structure (3) forms a gap with the semiconductor substrate (1) in the vertical direction. The second multilayer film cantilever beam structure (4) is composed of a metal thin film (13), a P+ type semiconductor thin film (14), and a P type semiconductor thin film (15) from top to bottom. One end of the second multilayer film cantilever beam structure (4) is connected to the second lead bonding region (6) to form a lead fixing end, and the other end of the second multilayer film cantilever beam structure (4) is connected to the insulating dielectric layer (2) to form a lead fixing end (8). The second multilayer film cantilever beam structure (4) forms a gap with the semiconductor substrate (1) in the vertical direction. The first multilayer film cantilever beam structure (3) and the second multilayer film cantilever beam structure (4) are kept on the same horizontal plane. The first multilayer membrane cantilever beam structure (3) is an arc-shaped structure, which is composed of a long-axis cantilever beam (9) and a short-axis cantilever beam (10) connected together. The second multilayer membrane cantilever beam structure (4) is an arc-shaped structure, which is composed of a long-axis cantilever beam (11) and a short-axis cantilever beam (12) connected together. The two mutually symmetrical arc-shaped cantilever beams form a parallel plate capacitor.

2. A micro-machined temperature sensor without self-heating effect according to claim 1, characterized in that: The semiconductor substrate (1) is a silicon substrate.

3. The micro-machined temperature sensor without self-heating effect according to claim 1, characterized in that: The insulating dielectric layer (2) is a silicon dioxide dielectric layer.

4. A micro-machined temperature sensor without self-heating effect according to claim 1, characterized in that: The metal thin film (13) is a gold thin film.

5. A micro-machined temperature sensor without self-heating effect according to claim 1, characterized in that: The P+ type semiconductor thin film (14) is a P+ type heavily doped silicon thin film.

6. A micro-machined temperature sensor without self-heating effect according to claim 1, characterized in that: The P-type semiconductor thin film (15) is a P-type single crystal silicon thin film.

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