CN116754089A - A micromachined temperature sensor without self-heating effect - Google Patents

Abstract

The invention discloses a micro-machined self-heating effect-free temperature sensor, which comprises a semiconductor substrate, an insulating medium layer, a multi-layer film cantilever beam structure and a wire bonding area. The multi-layer 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 arched cantilever beams, wherein each cantilever beam is formed by connecting a long shaft cantilever beam and a short shaft cantilever beam, and two ends of each cantilever beam are fixed and led out through a wire bonding area. The two arched cantilever beams form a parallel plate capacitor to form a temperature sensitive capacitor of the sensor. When the temperature changes, the cantilever beams deflect in the horizontal plane due to different deformation of the long axis and the short axis of the cantilever beams, and the two cantilever beams are symmetrically distributed and arranged, so that the two cantilever beams can move in opposite directions, and finally the capacitance of the parallel flat plate is changed. Meanwhile, the capacitor has no direct current power consumption, and only needs to use an alternating current small signal during measurement, so that the sensor is not influenced by self-heating effect, and the accuracy is high.

Description

A micromachined temperature sensor without self-heating effect

Technical field

The invention relates to a micromachined temperature sensor, and in particular to a micromachined temperature sensor without self-heating effect.

Background technique

Temperature is closely related to people's daily life, and the research on temperature measurement and temperature sensors has a very long history. There are currently many types of temperature sensors with various temperature measurement principles. The development history of temperature sensors has generally evolved 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 micro electronic products.

With the development and progress of micromachining technology, the advantages of semiconductor temperature sensors such as small size, small heat capacity and fast response have been reflected. Most of the temperature measurement principles of 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-electromechanical systems) technology, piezoresistive, resonant, polysilicon micro-bridge, bimetal cantilever and other MEMS temperature sensors have been continuously developed. Most of the existing temperature sensors use resistance or current as sensitive outputs. The biggest disadvantage of these sensors is their large power consumption, and their self-heating effect will affect the temperature measurement.

Contents of the invention

Purpose of the invention: In view of the above-mentioned existing technology, a micromachined temperature sensor without self-heating effect is provided, which can avoid the interference of self-heating effect on temperature measurement and improve the accuracy.

Technical solution: a micromachined temperature sensor without self-heating effect, including a semiconductor substrate, an insulating dielectric layer provided on the surface of the semiconductor substrate, a first multi-layer film cantilever beam structure, and a second multi-layer film cantilever beam structure , first wire bonding area, second wire bonding area:

The first multi-layer film cantilever beam structure includes a metal film, a P+ type semiconductor film and a P-type semiconductor film arranged from top to bottom. One end of the first multi-layer film cantilever beam structure is connected to the first The wire bonding area is connected to form a wire fixed end, and the other end of the first multi-layer film cantilever beam structure is connected to the insulating dielectric layer to form a lead fixed end. The first multi-layer film cantilever beam structure is in the vertical direction. forming a gap between the top and the semiconductor substrate;

The second multi-layer film cantilever beam structure includes a metal film and a semiconductor film. One end of the second multi-layer film cantilever beam structure is connected to the second wire bonding area to form a lead fixed end. The other end of the second multi-layer film cantilever beam structure is connected to the insulating dielectric layer to form a lead fixed end, and a gap is formed between the second multi-layer film cantilever beam structure and the semiconductor substrate in the vertical direction; The first multi-layer film cantilever beam structure and the second multi-layer film cantilever beam structure are maintained on the same horizontal plane.

Further, the first multi-layer film cantilever beam structure is an arcuate structure, which is composed of a long-axis cantilever beam and a short-axis cantilever beam. The second multi-layer film cantilever beam structure is an arcuate structure, which is composed of a long-axis cantilever beam. The cantilever beam and the short-axis cantilever beam are connected.

Further, the semiconductor substrate is a silicon substrate.

Further, the insulating dielectric layer is a silicon dioxide dielectric layer.

Further, the metal film is a gold film.

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

Further, the P-type semiconductor film is a P-type single crystal silicon film.

Beneficial effects: Compared with the existing technology, the present invention has the following advantages:

1. The temperature sensor structure of the present invention forms a variable parallel plate capacitance. The multilayer film cantilever beam structure consists of two mutually symmetrical arcuate cantilever beams. Each arcuate cantilever beam is composed of a long-axis cantilever beam and a short-axis cantilever beam, and its two ends are fixed and lead out through the wire bonding area. Two mutually symmetrical arcuate cantilever beams form a parallel plate capacitor, which constitutes the temperature-sensitive capacitor of the temperature sensor of the present invention. When the temperature changes, due to the different deformations of the long axis and short axis in the arcuate cantilever beam, the arcuate cantilever beam deflects in the horizontal plane, and because the two arcuate cantilever beams form a symmetrical layout in the horizontal plane, the two arcuate cantilever beams are The arcuate cantilever beam will move in the opposite direction, ultimately causing a change in the parallel plate capacitance. Therefore, the temperature-sensitive capacitance is larger than that of traditional capacitive micromachined temperature sensors, so the accuracy of the sensor is high.

2. The temperature sensor of the present invention uses a capacitor as a sensitive element for temperature measurement. Since the capacitor does not consume DC power and only needs to use an AC small signal when measuring the capacitance, the sensor is not affected by the self-heating effect.

Description of the drawings

Figure 1 is a top view of the present invention;

Figure 2 is a cross-sectional view along A-A’ of the structure of the present invention.

Detailed ways

The present invention will be further explained below in conjunction with the accompanying drawings.

As shown in Figures 1 and 2, a micromachined temperature sensor without self-heating effect includes a semiconductor substrate 1, an insulating dielectric layer 2 provided on the surface of the substrate, a first multi-layer film cantilever structure 3, a second The multi-layer film cantilever structure 4 is composed of a first wire bonding area 5 and a second wire bonding area 6; the first multi-layer film cantilever structure 3 is composed of a metal film 13 and a P+ type semiconductor from top to bottom. The film 14 is composed of a P-type semiconductor film 15. One end of the first multi-layer film cantilever beam structure 3 is connected to the first wire bonding area 5 to form a wire fixed end. The first multi-layer film cantilever beam structure 3 The other end is connected to the insulating dielectric layer 2 to form a fixed end 7, and a gap is formed between the first multilayer film cantilever structure 3 and the semiconductor substrate 1 in the vertical direction; the second multilayer film cantilever The beam structure 3 is composed of a metal film 13, a P+ type semiconductor film 14 and a P-type semiconductor film 15 from top to bottom. One end of the second multi-layer film cantilever beam structure 4 is connected to the second wire bonding area 6 to form The lead fixed end, the other end of the second multi-layer film cantilever beam structure 4 is connected to the insulating dielectric layer 2 to form a fixed end 8, the second multi-layer film cantilever beam structure 4 is connected with the semiconductor liner in the vertical direction. A gap is formed between the bottoms 1; the first multi-layer film cantilever beam structure 3 and the second multi-layer film cantilever beam structure 4 are maintained at the same horizontal plane.

Wherein, the first multi-layer film cantilever beam structure 3 is an arcuate structure, which is composed of a long-axis cantilever beam 9 and a short-axis cantilever beam 10 connected, and the second multi-layer film cantilever beam structure 4 is an arcuate structure, It consists of a long-axis cantilever beam 11 and a short-axis cantilever beam 12 connected. The semiconductor substrate 1 is a silicon substrate, the insulating dielectric layer 2 is a silicon dioxide dielectric layer, and the metal film 13 is a gold film. The P+ type semiconductor film 14 is a P+ type heavily doped silicon film, and the P type semiconductor film 15 is a P type single crystal silicon film.

The micromachined temperature sensor without self-heating effect of the present invention can be prepared by the following process:

a: The surface of SOI (silicon on insulator) wafer is heavily doped to form a P+ layer;

b: Deposit metal layer and pattern photolithography;

c: The metal layer is used as a mask for deep reactive ion etching to etch the silicon to the oxide layer;

d: Etching removes the oxide layer and releases the structure.

The working principle of the micromachined temperature sensor without self-heating effect of the present invention is as follows: the multi-layer film cantilever beam structure is composed of two mutually symmetrical first multi-layer film cantilever beam structures 3 and second multi-layer film cantilever beam structures 4. An arcuate cantilever beam is composed of a long-axis cantilever beam and a short-axis cantilever beam. Two mutually symmetrical arcuate cantilever beams form a parallel plate capacitor, which constitutes the temperature-sensitive capacitor of the temperature sensor of the present invention. When the temperature changes, due to the difference in deformation caused by the heating of the long axis and the short axis of the arcuate cantilever beam, the arcuate cantilever beam deflects in the horizontal plane, and because the two arcuate cantilever beams are arranged in a symmetrical layout in the horizontal plane, the arcuate cantilever beam deflects in the horizontal plane. The two arcuate cantilever beams will move in opposite directions, ultimately causing the capacitance of the parallel plates to change.

The working process of the micromachined temperature sensor without self-heating effect of the present invention: when the ambient temperature rises, the length increase of the long-axis cantilever beam 9 in the first multi-layer film cantilever beam structure 3 is greater than that of the short-axis cantilever beam 10, resulting in In the horizontal plane, the long-axis cantilever beam 9 will deflect in the direction of the short-axis cantilever beam 10, and at the same time, the long-axis cantilever beam 11 in the second multi-layer film cantilever beam structure 4 will also deflect in the direction of the short-axis cantilever beam 12, resulting in The gap between the first multi-layer film cantilever beam structure 3 and the second multi-layer film cantilever beam structure 4 becomes larger, which ultimately increases the parallel plate capacitance, that is, the temperature-sensitive capacitance will increase; when the ambient temperature decreases, the first The length reduction of the long-axis cantilever beam 9 in the multi-layer film cantilever beam structure 3 is greater than that of the short-axis cantilever beam 10, causing the short-axis cantilever beam 10 to deflect in the direction of the long-axis cantilever beam 9 in the horizontal plane. At the same time, the second multi-layer The short-axis cantilever beam 12 in the membrane cantilever beam structure 4 will also deflect toward the long-axis cantilever beam 11, causing the gap between the first multi-layer membrane cantilever beam structure 3 and the second multi-layer membrane cantilever beam structure 4 to change. Small, eventually the parallel plate capacitance will be reduced, that is, the temperature-sensitive capacitance will be reduced.

Before using the micromachined temperature sensor without self-heating effect of the present invention, the temperature sensor is first calibrated using standard equipment to establish the corresponding relationship between the temperature value and the capacitance value. During measurement, the output capacitance value of the temperature sensor is monitored and compared with the calibration value to obtain the temperature value to be measured.

The above are only preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, several improvements can be made without departing from the principles of the present invention, and these improvements should also be regarded as the present invention. protection scope of the invention.

Claims (7)

1. A micromachined temperature sensor without self-heating effect, characterized by: comprising a semiconductor substrate (1), an insulating dielectric layer (2) provided on the surface of the semiconductor substrate (1), and a first multilayer film Cantilever beam structure (3), second multilayer film cantilever beam structure (4), first wire bonding area (5), second wire bonding area (6): The first multi-layer cantilever beam structure (3) includes a metal film (13), a P+ type semiconductor film (14) and a P-type semiconductor film (15) arranged from top to bottom. One end of the film cantilever beam structure (3) is connected to the first wire bonding area (5) to form a lead fixed end, and the other end of the first multilayer film cantilever beam structure (3) is connected to the insulated The dielectric layer (2) is connected to form a lead fixed end (7), and a gap is formed between the first multilayer film cantilever structure (3) and the semiconductor substrate (1) in the vertical direction; The second multi-layer film cantilever beam structure (4) includes a metal film (13) and a semiconductor film (16), and one end of the second multi-layer film cantilever beam structure (4) is connected to the second lead The bonding area (6) is connected to form a lead fixed 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 fixed end (8). A gap is formed between the two multi-layer film cantilever beam structures (4) and the semiconductor substrate (1) in the vertical direction; the first multi-layer film cantilever beam structure (3) and the second multi-layer film cantilever beam structure (3) are The membrane cantilever beam structure (4) is maintained at the same level. 2. A micromachined temperature sensor without self-heating effect according to claim 1, characterized in that: the first multi-layer film cantilever beam structure (3) is an arcuate structure, consisting of a long-axis cantilever beam (9 ) is connected to a short-axis cantilever beam (10). The second multi-layer film cantilever beam structure (4) is an arcuate structure and is composed of a long-axis cantilever beam (11) and a short-axis cantilever beam (12). . 3. A micromachined temperature sensor without self-heating effect according to claim 1, characterized in that: the semiconductor substrate (1) is a silicon substrate. 4. A micromachined temperature sensor without self-heating effect according to claim 1, characterized in that: the insulating dielectric layer (2) is a silicon dioxide dielectric layer. 5. A micromachined temperature sensor without self-heating effect according to claim 1, characterized in that: the metal film (13) is a gold film. 6. A micromachined temperature sensor without self-heating effect according to claim 1, characterized in that: the P+ type semiconductor film (14) is a P+ type heavily doped silicon film. 7. A micromachined temperature sensor without self-heating effect according to claim 1, characterized in that: the P-type semiconductor film (15) is a P-type single crystal silicon film.