CN205506741U - AlN thermal insulation bilateral structure low -grade fever board gas sensor - Google Patents

Abstract

A micro-hot plate gas sensor with AlN thermal isolation double-sided structure, including AlN ceramic substrate, heater, heater pad, signal electrode, signal electrode pad, pad through hole, trapezoidal thermal isolation groove, sensitive film, substrate The front of the chip is provided with signal electrodes, signal electrode pads, heater pads, and sensitive films. The signal electrodes adopt an interdigital electrode structure, and the sensitive film is attached to the signal electrodes; The electrode pads and the heater adopt a serpentine arrangement structure; the pads on the front and back of the substrate are connected through etched pad through holes; trapezoidal thermal isolation grooves are etched around the central heating area of the substrate to reduce the sensor’s heat loss. The overall size of the sensor is about 3.2mm*3.2mm*0.2mm. The gas sensor of the utility model has the advantages of small size, low power consumption, high sensitivity, etc., and can be used as a semiconductor gas sensor for Cl ₂ , NO ₂ , CH ₄ , etc.

Description

An AlN thermally isolated double-sided micro-hotplate gas sensor

technical field

The invention relates to the technical field of sensors, in particular to a micro-hot plate gas sensor with an AlN base thermally isolated double-sided structure.

Background technique

In recent years, atmospheric smog pollution has become more and more serious, and vicious accidents such as various gas leakage and explosions have occurred frequently, which has brought great inconvenience to people's lives, so the detection of gases is particularly important. At present, in various gas detection fields, semiconductor gas sensors are widely used, which have the advantages of high sensitivity, low cost, good repeatability, and easy mass production. The working principle of the semiconductor gas sensor is that the metal oxide sensitive material undergoes adsorption and desorption reactions on the surface of the sensor and the material at a certain temperature, causing a change in the conductivity of the material, thereby realizing the detection of the gas. However, in order to make the semiconductor gas sensitive material reach the optimum working temperature, traditional discrete gas sensors often consume large power consumption, resulting in excessive power consumption of the system.

With the rapid development of MEMS technology, micro hot plate gas sensors with small size and low power consumption have been paid more and more attention. However, micro-hotplate sensors made of silicon substrates have disadvantages such as poor thermal matching of the film base, resulting in poor temperature stability and complicated manufacturing processes, which restrict the development of gas sensors. AlN ceramic materials are widely used in the field of microelectronics due to their high heat transfer capacity, stable dielectric properties and good film-base bonding properties. With the continuous maturity of MEMS technology, non-silicon-based ceramics, etc., as substrate materials for microstructure sensors, have broad application prospects.

Contents of the invention

The purpose of the present invention is to solve the shortcomings of the existing gas sensor such as excessive heat loss and complicated process, and propose an AlN heat-isolated double-sided structure micro-hot plate gas sensor. The sensor of the invention has the advantages of small size, low power consumption, high sensitivity and the like. The sensor of the present invention adopts the double-sided structure of the micro-hot plate, and the signal electrode and the heater are respectively designed on different planes of the micro-hot plate. The sensitive film is sputtered and plated at the middle position of the signal electrode. The heat isolation groove structure is adopted to effectively solve the problems of excessive power consumption, excessive heat loss and connection reliability of the sensor during use.

The present invention is realized through the following technical solutions.

AlN thermally isolated double-sided structure micro-hot plate gas sensor, including: AlN ceramic substrate, heater, heater pad, signal electrode, signal electrode pad, pad through hole, trapezoidal thermal isolation groove, sensitive film, in the The front of the AlN ceramic substrate is provided with a signal electrode, a signal electrode pad, a heater pad, a sensitive film, and the signal electrode adopts an interdigital electrode structure; the back of the AlN ceramic substrate is provided with a heater, a heater Pads, signal electrode pads, and heaters are arranged in a serpentine structure with gaps in the middle. The heater pads on the front side of the AlN ceramic substrate and the heater pads on the back side, and the signal electrode pads on the front side and the signal pads on the back side The pads are connected by pad through-hole structure to improve the stability of the leads in the packaging process. Four trapezoidal heat isolation grooves are etched in the directions around the central heating area of the AlN ceramic substrate to reduce heat conduction loss.

The heater and the heater pad are made of metal Pt material. The heater adopts a serpentine arrangement structure, and the heater pad plane adopts a square structure, and its thickness is consistent with that of the heater. Mainly use the magnetron sputtering method to sputter the Pt material onto the AlN ceramic substrate, and then use the photolithography stripping process to manufacture the required heater and pad structure.

The signal electrodes and the signal electrode pads are made of metal Pt material. The signal electrode adopts an interdigitated electrode structure, and the pad plane of the signal electrode adopts a square structure, and its thickness is consistent with that of the signal electrode. The magnetron sputtering method is also used to sputter the Pt material onto the AlN ceramic substrate, and then the required signal electrode and pad structure is produced by a photolithographic lift-off process.

The pad through hole is cylindrical, and its hole depth is consistent with the sum of the thickness of the upper and lower pads and the thickness of the AlN ceramic substrate. The manufacturing process is etched by laser micromachining technology.

The sensitive film is metal oxide semiconductor material such as SnO ₂ , In ₂ O ₃ .

The thermal isolation groove has a trapezoidal structure, and the depth of the groove is consistent with the thickness of the AlN ceramic substrate. It is etched by laser micromachining process.

Compared with the prior art, the present invention has the following beneficial effects.

(1) The AlN thermally isolated double-sided structure micro-hot plate gas sensor prepared by photolithography stripping process and laser micromachining process adopts the structure design of serpentine heater and interdigital signal electrode to improve the heating efficiency and the sensitivity of the sensor.

(2) The present invention adopts the laser micromachining process to etch the thermal isolation groove to reduce the heat loss and the heating power consumption of the sensor.

(3) The sensor designed in the present invention has the advantages of small size, low power consumption, simple process, and low development cost, and can be used as a semiconductor gas sensor for Cl ₂ , NO ₂ , CH ₄ , etc., and has broad development prospects.

(4) The present invention adopts the pad design with through holes, leads the lead wires on the pads by welding, facilitates the use of electronic packaging technology, packages the sensors into chips, and improves the stability of the lead package.

Description of drawings.

Figure 1 is an assembly diagram of the sensor of the present invention.

Fig. 2 is a schematic diagram of the front structure of the sensor of the present invention.

Fig. 3 is a schematic diagram of the back structure of the sensor of the present invention.

Fig. 4 is a sectional view along A-A shown in Fig. 2 .

In Figure 1: 1 is the heater, 2 is the heater pad, 3 is the signal electrode pad, 4 is the AlN ceramic substrate, 5 is the signal electrode, 6 is the through hole of the pad, 7 is the sensitive film, and 8 is the trapezoid Thermal isolation slot.

detailed description.

The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings: this embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following the described embodiment.

As shown in Figures 1 to 4, this embodiment includes a heater 1, a heater pad 2, a signal electrode pad 3, an AlN ceramic substrate 4, a signal electrode 5, a pad through hole 6, a sensitive film 7, and a trapezoidal thermal pad. Isolation groove 8; heater pad 2 is composed of pad 2-1, pad 2-2, pad 2-3, and pad 2-4; signal electrode pad 3 is composed of pad 3-1, pad 3 -2. Composed of pad 3-3 and pad 3-4, signal electrode 5 is composed of electrode 5-1 and electrode 5-2, pad through hole 6 is composed of through hole 6-1 and through hole 6-2 , through hole 6-3, through hole 6-4, through hole 6-5, through hole 6-6, through hole 6-7, through hole 6-8, through hole 6-9, through hole 6-10, through hole Hole 6-11, through hole 6-12, trapezoidal thermal isolation groove 8 is composed of trapezoidal groove 8-1, trapezoidal groove 8-2, trapezoidal groove 8-3, trapezoidal groove 8-4, pad 2-1 and welding The plate 2-3 is connected by the through hole 6-1, the through hole 6-5, and the through hole 6-9, and the pad 2-2 and the pad 2-4 are connected by the through hole 6-3, the through hole 6-7, and the through hole 6-7. The holes 6-11 are connected, the pad 3-2 is connected with the pad 3-4 by the through hole 6-4, the through hole 6-8, and the through hole 6-12, and the pad 3-1 is connected with the pad 3-3 Connected by the through hole 6-2, the through hole 6-6, and the through hole 6-10, the signal electrode 5 is located on the AlN ceramic substrate 4, the signal electrode 5 is connected to the signal electrode pad 3, and the sensitive film 7 is located on the signal electrode 5; the heater 1 is located under the AlN ceramic substrate 4, and the heater 1 is connected to the heater pad 2.

In this embodiment, when the gas sensor is working, a DC voltage is applied to the heater 1 and the heater pad 2. Since the metal Pt material used in the heater 1 and the heater pad 2 has a certain resistance value, the DC voltage Under the action of the heater 1, heat will be generated, and through the heat conduction of the AlN ceramic substrate 4, this heat will be transferred to the signal electrode 5 and the sensitive film 7, so that the metal oxide semiconductor gas sensitive material will obtain 200-400 °C working temperature.

In this embodiment, the shape of the sensor is a square with a side length of 3.2 mm, a thickness of the substrate 4 of 0.2 mm, and a size of the substrate material AlN ceramic substrate 4 of 3.2 mm*3.2 mm*0.2 mm.

In this embodiment, the pad plane is a square with a size of 0.5mm*0.5mm*500nm.

In this embodiment, the line width of the heater 1 is 0.1mm, the spacing is 0.05mm, and the thickness is 0.5um; the area of the central heating zone is 1mm*1mm.

In this embodiment, the line width of the signal electrode 5 is at most 0.1mm, at least 0.05mm, and the line thickness is 500nm; the distance between the electrode 5-1 and the electrode 5-2 is at most 0.1mm, at least 0.05mm.

In this embodiment, the trapezoidal through hole of the trapezoidal thermal isolation groove 8 is an isosceles trapezoid with an upper bottom size of 0.8 mm, a lower bottom size of 1.7 mm, and a height of 0.45 mm, and its thickness is 0.2 mm.

In this embodiment, the welding through hole 6 is a cylinder with a bottom radius of 0.1mm and a height of 201um.

This embodiment adopts MEMS process technology to prepare, adopts magnetron sputtering process and photolithography stripping process to prepare signal electrode, heating electrode and pad; adopts laser micromachining process to etch pad through hole and trapezoidal thermal isolation groove, solves the problem of sensor The lead package has poor stability and excessive heat loss.

Claims (5)

1. an AlN is thermally isolated bilateral structure micro-hotplate gas sensor, including: AlN ceramic substrate, heater, heater pad, signal electrode, signal electrode pad, welding plate hole, trapezoidal groove, sensitive membrane are thermally isolated, signal electrode, signal electrode pad, heater pad it is provided with in the front of described AlN ceramic substrate, sensitive membrane, signal electrode uses interdigitated electrode structure；The back side of described AlN ceramic substrate is provided with heater, signal electrode pad, heater pad, heater is the middle serpentine arrangement structure with gap, the heater pad in AlN ceramic substrate front all uses welding disc through hole structure to be connected with the heater pad at the back side, the signal electrode pad in front with the signal pad at the back side, to improve the stability of lead-in wire in packaging technology.In the orientation of described AlN ceramic substrate center thermal treatment zone surrounding, etching four is trapezoidal is thermally isolated groove.

AlN the most according to claim 1 is thermally isolated bilateral structure micro-hotplate gas sensor, it is characterized in that: described heater and heater pad, using Pt metal material, heater uses serpentine arrangement structure, heater pad plane uses square structure, and its thickness is consistent with heater thickness.

AlN the most according to claim 1 is thermally isolated bilateral structure micro-hotplate gas sensor, it is characterized in that: described signal electrode uses Pt metal material with signal electrode pad, signal electrode uses interdigitated electrode structure, signal electrode pad plane uses square structure, its thickness and signal electrode consistency of thickness.

AlN the most according to claim 1 is thermally isolated bilateral structure micro-hotplate gas sensor, it is characterised in that: described welding plate hole is cylindrical, uses laser micro process etching to form.

AlN the most according to claim 1 is thermally isolated bilateral structure micro-hotplate gas sensor, it is characterised in that it is trapezium structure that groove is thermally isolated described in:, and groove depth is consistent with AlN ceramic substrate thickness, uses laser micro process etching to form.