CN101034083B

CN101034083B - Manufacturing method of sonic surface wave gas sensor

Info

Publication number: CN101034083B
Application number: CN2007100643330A
Authority: CN
Inventors: 李强; 李冬梅; 潘峰
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2007-03-12
Filing date: 2007-03-12
Publication date: 2011-01-26
Anticipated expiration: 2027-03-12
Also published as: CN101034083A

Abstract

This invention discloses a manufacturing method of acoustic surface wave gassy sensor which belongs to sensor manufacturing engineering. This method is coating a layer active metal ( Al, Mg, Zn, Sn) on gassy sensor figure that will grow sensitivity film, then through photoengraving and wet method sculpture to make the aurum ( Ag or Pt) membrane that demand self assembly sensitivity film expose. the transducer IDT is covered up by active metal, at last carry out monomolecular self assembly, then immerge device after self assembly to in common use alkali or acid corrosion solution to wipe off active metal. This invention supply method of accurately self assembly sensitivity membrane on aurum (or Pt) membrane surface in sound propagation path, and shield rest aurum (Ag or Pt) membrane. At the same time the method advances the size precision of self assembly sensitivity membrane. So greatly advance precision of acoustic surface wave gassy sensor.

Description

The manufacture method of sonic surface wave gas sensors

Technical field

The invention belongs to the manufacturing technology of sensor, particularly the manufacture method of a kind of sonic surface wave gas sensors of SAW (Surface Acoustic Wave) device.

Background technology

Surface acoustic wave (SAW) is a kind of sound wave of propagating along elastic matrix surface, because surface acoustic wave carries out transducing and propagation at dielectric surface, so the injection of information, extraction, processing all can realize easily.Surface acoustic wave sensor was come out the seventies in last century, and it is the up-and-coming youngster of sensor.The ultimate principle of sonic surface wave gas sensors is the variation that causes surface acoustic wave sensor speed by the absorption that the sensitive membrane that the SAW (Surface Acoustic Wave) device surface is covered is treated side gas, thereby change the oscillation frequency of SAW oscillator, realize monitoring and measurement gas with this.Compare with the sensor of other types, sonic surface wave gas sensors has a lot of excellent characteristic, have that volume is little, in light weight, precision is high, resolution is high, antijamming capability is strong, characteristics such as highly sensitive, valid analysing range good linearity, can utilize the plane manufacture craft in the integrated circuit, can realize microminiaturization and integrated, be suitable for producing low-costly and in high volume.

The problem that exists:

Making a well behaved SAW (Surface Acoustic Wave) device, is a very meticulous job.When making sonic surface wave gas sensors, need be on the acoustic propagation path deposit one deck selective absorbing film, the area of absorbing film is decided by the size in transducer aperture and the center distance of two transducers.The width of absorbing film is more than or equal to the aperture of output transducer.In order to improve the stability of sensor, the quality that absorbing film produces on the acoustic propagation path loads more little, and then the sonic surface wave gas sensors precision is high more.Based on this, go up the chemisorbed film that self assembly one deck has certain molecule distinguishability at some metal (as Au, Ag or Pt film), caused that people pay close attention to greatly.But self assembly sensitive membrane on Au or Pt film selectively, and cover the difficulty that other golden transducer produces.

Summary of the invention

The manufacture method that the purpose of this invention is to provide a kind of sonic surface wave gas sensors.It is characterized in that: this method is for to want (the Al of evaporation one deck active metal on the gas sensor figure of grow sensitivity film, Mg, Zn, Sn etc.), pass through photoetching and wet etching again, to need gold (Ag or the Pt) film of self assembly sensitive membrane to expose out, transducer IDT is covered by the active metal, carry out the deposition (depositional mode can be physical deposition such as spraying process also can be chemogenic deposit such as molecule self assembly etc.) of selective absorbing film then, again device is immersed in general alkali or the acid etching solution at last and remove the active metal, the part of covering is exposed out.

Concrete step of preparation process:

1. evaporation one deck 10-50nm active metal layer 4 on the good gas sensor figure of the photoetching of piezoelectric base unit 1 with electron beam or thermal evaporation method, the gas sensor figure that wherein photoetching is good comprises the metallic film 3 that is used for grow sensitivity film on IDT interdigital transducer 2 and the travel path;

2. photoetching and wet etching active metal layer 4 expose the metallic film 3 on the acoustic propagation path, and IDT interdigital transducer 2 parts are covered up by active metal layer 4;

3. with physics or chemical method grow sensitivity film 5 on exposed sensitive membrane 3;

4. the product with step 3 immerses removal active metal layer in general alkali or the acid etching solution, with not needing the position 2 of grow sensitivity film to expose out again, promptly finishes the making of sonic surface wave gas sensors.

Described active metal layer is Al, Mg, Zn or Sn.

The metallic film 3 of described grow sensitivity film is Au, Ag or Pt.

The metallic film of described making IDT interdigital transducer 2 is Au, Ag or Pt.

Described sensitive membrane is high molecular polymer or metal or metal oxide.

The invention has the beneficial effects as follows provides accurately the only surface self assembly of gold (or Pt) film on acoustic propagation path sensitive membrane, and protects the method for other gold (Ag or Pt) film, has improved the size accuracy of self assembly sensitive membrane.Thereby improved the precision of sonic surface wave gas sensors greatly.

Description of drawings

Fig. 1 is the schematic flow sheet of the surface acoustic wave sensor sensitive membrane of selectively growing among the present invention.

Embodiment

The present invention provides a kind of manufacture method of sonic surface wave gas sensors.Specifically step of preparation process is as shown in Figure 1:

1. evaporation one deck 10-50nm active metal layer 4 (Al on the good gas sensor figure of the photoetching of piezoelectric base unit 1 with electron beam or thermal evaporation method, Mg, Zn, Sn etc.) (as shown in Figure 1a), the gas sensor figure that wherein photoetching is good comprises the metallic film 3 that is used for grow sensitivity film on IDT interdigital transducer 2 and the travel path;

2. photoetching and wet etching active metal layer 4 expose the metallic film 3 (Au, Ag or Pt) of the grow sensitivity film on the acoustic propagation path, and IDT interdigital transducer 2 parts (Au, Ag or Pt) are all covered up (shown in Fig. 1 b) by active metal layer 4 (as Al);

3. with physics (as spraying process) or chemical method (as the molecule self assembly) grow sensitivity film 5 (shown in Fig. 1 c) on the metallic film 3 of grow sensitivity film;

4. the product of step 3 is put into general alkali or acid etching solution and removed metal A l, will not need the position of grow sensitivity film to expose out again, promptly finish the making (shown in Fig. 1 d) of sonic surface wave gas sensors.

Claims

1. the manufacture method of a sonic surface wave gas sensors, it is characterized in that: this method is for to want evaporation one deck active metal on the gas sensor figure of grow sensitivity film, pass through photoetching and wet etching again, to need the position of self assembly sensitive membrane to expose out, the IDT interdigital transducer is covered by the active metal, carry out the unimolecule self assembly then, again that self assembly is good device immerses the active metal that removal is covered in general alkali or the acid etching solution;

Concrete step of preparation process:

1) evaporation one deck 10-50nm active metal layer (4) on the good gas sensor figure of the photoetching of piezoelectric base unit (1) with electron beam or thermal evaporation method, the gas sensor figure that wherein photoetching is good comprises the metallic film (3) that is used for grow sensitivity film on IDT interdigital transducer (2) and the travel path;

2) photoetching and wet etching active metal layer (4) expose the metallic film that is used for grow sensitivity film (3) on the acoustic propagation path, and IDT interdigital transducer (2) part is all covered up by active metal layer (4);

3) go up grow sensitivity film (5) with physics or chemical method at the metallic film (3) of grow sensitivity film;

4) product of step 3) is put into general alkali or acid etching solution and removed the active metal layer,, promptly finish the making of sonic surface wave gas sensors not needing the position of long sensitive membrane to expose out again.

2. according to the manufacture method of the described sonic surface wave gas sensors of claim 1, it is characterized in that: described active metal layer is a kind of among Al, Mg, Zn, the Sn.

3. according to the manufacture method of the described sonic surface wave gas sensors of claim 1, it is characterized in that: the metallic film of described grow sensitivity film (3) is Au, Ag or Pt.

4. according to the manufacture method of the described sonic surface wave gas sensors of claim 1, it is characterized in that: the metallic film of described IDT interdigital transducer (2) is Au, Ag or Pt.

5. according to the manufacture method of the described sonic surface wave gas sensors of claim 1, it is characterized in that: described sensitive membrane is high molecular polymer or metal or metal oxide.