CN204154680U

CN204154680U - A kind of MEMS methane transducer

Info

Publication number: CN204154680U
Application number: CN201420643827.XU
Authority: CN
Inventors: 马洪宇; 丁恩杰; 刘晓文; 赵小虎
Original assignee: China University of Mining and Technology CUMT
Current assignee: China University of Mining and Technology CUMT
Priority date: 2014-10-31
Filing date: 2014-10-31
Publication date: 2015-02-11
Anticipated expiration: 2024-10-31

Abstract

A kind of MEMS methane transducer, is applicable to colliery and detects use.It comprises P-type silicon substrate, forms N-type silicon in described P-type silicon substrate front; Silicon heating component is prepared with the N-type silicon processing in described P-type silicon substrate; Described silicon heating component comprises two stiff ends, silicon well heater, two silicon cantilevers; This sensor is using common monocrystalline silicon as the material of heating element, and heating element simultaneously as sensitive element, and does not need catalyst support and catalyst material; This sensor have cost low, highly sensitive, low in energy consumption, highly sensitive, measure do not affect by oxygen concentration, be not subject to carbon distribution, Poisoning Effect advantage.

Description

A kind of MEMS methane transducer

Technical field

The utility model relates to a kind of methane transducer, is particularly useful for the MEMS methane transducer used during a kind of mine safety detects.

Background technology

Along with the development of Internet of Things, current methane transducer cannot meet the demand of individual equipment to the methane transducer of the detection low-concentration methane of low-power consumption, long-life, low cost.That at present detects low-concentration methane for underground coal mine is still the catalytic combustion type methane transducer heated based on traditional platinum filament, its power consumption is larger, the use of catalyzer causes CH_4 detection unstable properties, checking time short, exists by carbon distribution, poisoning, activation etc. because of shortcomings such as the harmful effects that uses catalyzer and bring; And infrared methane sensor price is high, sensing element has a strong impact on by dust and steam; These two kinds of methane transducers are not well positioned to meet the application demand of Internet of Things to low-power consumption methane transducer.And other methane transducer also cannot adapt to the complex environment of underground coal mine high humility.

Summary of the invention

The purpose of this utility model to provide a kind of structure simple, do not use catalyzer can have the MEMS methane transducer of high-sensitivity detection ability and application thereof and preparation method to low-concentration methane (0 ~ 4%) again.

For realizing above-mentioned technical matters, MEMS methane transducer of the present utility model take P-type silicon as substrate, and P-type silicon substrate is provided with N-type silicon; Silicon heating component is prepared with the N-type silicon processing in described P-type silicon substrate; Described silicon heating component comprises two stiff ends, silicon well heater, two silicon cantilevers; Described single silicon jib-length at least 300um; One end of described single silicon cantilever is connected with silicon well heater, and the other end is connected with a stiff end, for silicon well heater provides electrical connection; Described two silicon cantilevers are parallel to be arranged side by side, form U-shaped cantilever design with silicon overall heater, is suspended from air by silicon well heater; Silicon well heater and the silicon cantilever outside surface of described silicon heating component are provided with passivation protection layer; Described stiff end is located in P-type silicon substrate, comprise the silicon oxide layer on N-type silicon, N-type silicon and be used as electricity and draw pad Pad metal, described electricity is drawn pad Pad metal and is located on the silicon oxide layer on N-type silicon, and electricity extraction pad Pad metal directly contacts formation Ohmic contact by the window of silicon oxide layer with the N-type silicon below it, electricity draws pad Pad metal and the N-type silicon layer contact portion under it does not have silicon oxide layer;

The isolated groove getting rid of N-type silicon is provided with around described silicon heating component and stiff end thereof, it is high-impedance state that described isolated groove makes between all the other the N-type silicon in the N-type silicon of described silicon heating component and stiff end thereof and P-type silicon substrate, between two stiff ends being especially located at the silicon heating component in P-type silicon substrate except the electric pathway be made up of silicon cantilever and silicon well heater without other circuit pathways.

Beneficial effect:

1, MEMS methane transducer of the present utility model take silicon heating component as heating element and detecting element, and does not use catalyzer, just can realize the highly sensitive detection to low-concentration methane gas; The silicon well heater of MEMS methane transducer of the present utility model adopts the parallel-connection structure of multiple silicon fire-bar, and have the larger pyrometric scale area contacted with air, contribute to the raising of sensitivity, sensitivity can reach 10mV/CH ₄%, such sensitivity directly can promote instrument, reaches the requirement of national standard;

3, MEMS methane transducer of the present utility model does not use catalyzer and catalytic carrier, and therefore, the performance of sensor, by the impact of catalyzer, does not exist catalyst activity and reduces the problems such as the sensitivity decrease caused, poisoning, activation;

4, the silicon well heater of MEMS methane transducer of the present utility model is outstanding in atmosphere and away from silicon substrate, distance is greater than more than 300um, silicon well heater can be heated to the high temperature of more than 500 DEG C by power that can be lower, well reduce the heat lost by silicon chip, therefore there is advantage low in energy consumption, power consumption about 80 ~ 90mW during single silicon heating component work;

5, the silicon heating component of MEMS methane transducer of the present utility model adopts the processing of the monocrystalline silicon of stable performance to obtain, and this makes methane transducer of the present utility model under hot operation state, have good stability and long life-span; The shortcomings such as the high temperature of the METAL HEATING PROCESS such as platinum, tungsten material more than 500 degrees Celsius easily volatilizees this is because monocrystalline silicon does not exist, migration, also do not exist polysilicon resistance at high temperature grain boundary resistance be easy to change, the shortcoming that cannot control; Meanwhile, the passivation layer arranged at the outside surface of silicon heating component of the present utility model also reduces the impact of external environment on above-mentioned components and parts, thus further increases the stability of methane transducer performance of the present utility model;

6, methane transducer of the present utility model adopts MEMS technology processing, and size is little, not only make biosensor power consumption low, and fast response time, can about 40ms be reached;

Advantage: the MEMS methane transducer its preparation method based on the two-way etch silicon of wet method that the utility model provides can be compatible with CMOS technology; Easy batch production and calibration; Can reduce costs, there is good consistance; Further, methane transducer size of the present utility model is little, fast response time, biosensor power consumption are low, highly sensitive, linearity of output signal is good; Sensor performance, not by catalysts influence, need not consider the complex effects of catalyzer, simple to have highly sensitive detectability to low-concentration methane when the performance of sensor is carried out to complex optimum and compensated.

Accompanying drawing explanation

Fig. 1 is the schematic top plan view of MEMS methane transducer of the present utility model.

Fig. 2 is the schematic top plan view of MEMS methane transducer of the present utility model after the preparation completing etching window figure on silicon wafer.

Fig. 3 is the A-A cross-sectional view in Fig. 1 of the present utility model.

Fig. 4 is the structural representation of the silicon well heater of the silicon heating component of MEMS methane transducer of the present utility model.

When Fig. 5 is the preparation MEMS methane transducer based on the two-way etch silicon of wet method of the present utility model electricity draw pad Pad metal, metal contact wires and part scribe line on silicon wafer schematic diagram.

Fig. 6 is the current-resistance family curve of the silicon heating component of the MEMS methane transducer based on the two-way etch silicon of wet method of the present utility model.

In figure: 01-P type silicon substrate, 02-N type silicon, 101-silicon heating component; 1011-silicon well heater, 1012-silicon cantilever, 1013-silicon fire-bar; 102-stiff end; 103-isolated groove, 20-silicon oxide layer, 21-electricity draws pad Pad metal; 22-passivation protection layer; 31-metal contact wires, 32-metal link, 40-scribe line.

Embodiment

Below in conjunction with accompanying drawing, an embodiment of the present utility model is further described:

As shown in Figure 1, Figure 2, Figure 3 shows, MEMS methane transducer of the present utility model comprises P-type silicon substrate 01, and P-type silicon substrate 01 is provided with N-type silicon 02; Silicon heating component 101 is prepared with N-type silicon 02 processing in described P-type silicon substrate 01; Described silicon heating component 101 comprises two stiff ends 102, silicon well heater 1011, two silicon cantilevers 1012; Described single silicon cantilever 1012 length at least 300um; One end of described single silicon cantilever 1012 is connected with silicon well heater 1011, and the other end is connected with a stiff end 102, for silicon well heater 1011 provides electrical connection; Described two silicon cantilevers 1012 are parallel to be arranged side by side, form U-shaped cantilever design with silicon well heater 1011 entirety, is suspended from air by silicon well heater 1011; Silicon well heater 1011 and silicon cantilever 1012 outside surface of described silicon heating component 101 are provided with passivation protection layer 22; Described stiff end 102 is located in P-type silicon substrate 01, comprise the silicon oxide layer 20 on N-type silicon 02, N-type silicon 02 and be used as electricity and draw pad Pad metal 21, described electricity is drawn pad Pad metal 21 and is located on the silicon oxide layer 20 on N-type silicon 02, and electricity is drawn pad Pad metal 21 and directly contact with the N-type silicon 02 below it by the window of silicon oxide layer 20 and form Ohmic contact, electric extraction pad Pad metal 21 and N-type silicon layer 02 contact portion under it does not have silicon oxide layer 20.

The isolated groove 103 getting rid of N-type silicon is provided with around described silicon heating component 101 and stiff end 102 thereof, it is high-impedance state that described isolated groove 103 makes between all the other the N-type silicon in the N-type silicon of described silicon heating component 101 and stiff end 102 thereof and P-type silicon substrate 01, between two stiff ends 102 being especially located at the silicon heating component 101 in P-type silicon substrate 01 except the electric pathway be made up of silicon cantilever 1012 and silicon well heater 1011 without other circuit pathways.

Fig. 4 is the structural representation of the silicon well heater 1011 of the silicon heating component of the MEMS methane transducer based on the two-way etch silicon of wet method of the present utility model; The structure of silicon well heater 1011 is as shown in Figure 4 the parallel connection of multiple silicon fire-bar 1013, in order to increase the pyrometric scale area contacted with air.

Fig. 6 be the MEMS methane transducer based on the two-way etch silicon of wet method of the present utility model the current-resistance family curve of silicon heating component.

A kind of CH_4 detection of sensor described in claim 1 that uses is applied, and use two CH_4 detection sensors, one of them contacts with surrounding air, and another carries out air-tight packaging, keeps sealing for isolated with surrounding air; Two that the used MEMS methane transducers based on the two-way etch silicon of wet method form Wheatstone bridge and detect brachium pontis; Two stiff ends 102 of the MEMS methane transducer based on the two-way etch silicon of wet method apply voltage or passes to that electric current makes the working point of silicon heating component 101 be arranged in operating point regions on the left of its current-resistance family curve turning point, the silicon well heater 1011 of heating element 101 generates heat, and it is characterized in that electrical heating temperature is more than 500 degrees Celsius; Described turning point is that electrical resistance curtage increases the point of greatest resistance occurred, when curtage continues to increase, resistance no longer continues to increase and reduces on the contrary; When there being methane gas to occur, contact with surrounding air the temperature of silicon well heater 1011 reduce, make the resistance generation marked change of the silicon heating component 101 including this silicon well heater 1011, the Wheatstone bridge consisted of the described MEMS methane transducer based on the two-way etch silicon of wet method realizes the detection of low-concentration methane gas.The power consumption of two silicon heating components, at about 180mW, outputs signal at about 10mv/CH ₄%.

Claims

1. a MEMS methane transducer, is characterized in that: it comprises P-type silicon substrate (01), and P-type silicon substrate (01) is provided with N-type silicon (02); Silicon heating component (101) is prepared with N-type silicon (02) processing in described P-type silicon substrate (01); Described silicon heating component (101) comprises two stiff ends (102), silicon well heater (1011), two silicon cantilevers (1012); Single silicon cantilever (1012) length at least 300um; One end of single silicon cantilever (1012) is connected with silicon well heater (1011), and the other end is connected with a stiff end (102), for silicon well heater (1011) provides electrical connection; Described two silicon cantilevers (1012) are parallel to be arranged side by side, form U-shaped cantilever design with silicon well heater (1011) entirety, is suspended from air by silicon well heater (1011); Silicon well heater (1011) and silicon cantilever (1012) outside surface of described silicon heating component (101) are provided with passivation protection layer (22); Described stiff end (102) is located in P-type silicon substrate (01), comprise the silicon oxide layer (20) on N-type silicon (02), N-type silicon (02) and be used as electricity and draw pad Pad metal (21), described electricity is drawn pad Pad metal (21) and is located on the silicon oxide layer (20) on N-type silicon (02), and electricity is drawn pad Pad metal (21) and directly contact with the N-type silicon (02) below it by the window of silicon oxide layer (20) and form Ohmic contact, electric extraction pad Pad metal (21) and N-type silicon layer (02) contact portion under it does not have silicon oxide layer (20);

The isolated groove (103) getting rid of N-type silicon is provided with around described silicon heating component (101) and stiff end (102) thereof, it is high-impedance state that described isolated groove (103) makes between all the other the N-type silicon in the N-type silicon of described silicon heating component (101) and stiff end (102) thereof and P-type silicon substrate (01), between two stiff ends (102) being especially located at the silicon heating component (101) in P-type silicon substrate (01) except the electric pathway be made up of silicon cantilever (1012) and silicon well heater (1011) without other circuit pathways.