CN1132317A

CN1132317A - Silicon microheating actuating pump and its mfg. tech

Info

Publication number: CN1132317A
Application number: CN 95117829
Authority: CN
Inventors: 周兆英; 杨岳; 叶雄英; 李勇
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 1995-12-08
Filing date: 1995-12-08
Publication date: 1996-10-02
Anticipated expiration: 2015-12-08
Also published as: CN1047432C

Abstract

A miniature silicon heat-driven pump based on bimetalheat-driving principle is composed of two silicon membranes, on which pump cavity, liquid passage and one-way valve are etched, bimetal layer consisting of monocrystal silicon film and aluminium film, and heating element between said two films, and features great action force because of its double drive structure, low drive voltage and simple structure.

Description

Silicon microheating actuating pump and manufacturing process thereof

The present invention relates to silicon microheating actuating pump, belong to the fluid varactor machine field.

Along with science and technology development, in electronic engineering, medical engineering, chemical engineering, in the bioengineering to TRACE ELEMENTS ANALYSIS, aspect such as micro circulation and cooling all needs the supply of micro fluid is controlled, micropump has obtained extensive studies and exploitation as a kind of miniature final controlling element, at present existing multiple different driving principle, the micropump of different structure, as the moving membrane pump (Fig. 1) of the hot gas of Dutch Twente university development, the electrostatically actuated miniature thin membrane pump (Fig. 2) of German Fraunhofer research institute exploitation, the piezoelectric actuated membrane pump (Fig. 3) of northeastern Japan university development.Fig. 1 is the moving membrane pump structural drawing of Dutch Twente university's hot gas.This pump has two glass substrates (1,2), three silicon chips (3,4,5) to form, utilize in the moving principle actuating of hot gas, the silicon chip (3,4) and be processed with air chamber (6), at silicon chip (3, heating element (7) is arranged 4), and silicon chip (5) is gone up flexible film (8) pump chamber (9) and one-way valve (10,11).Gas in heating element during work (7) the heating air chamber (6) makes it to expand, and compressing film (8) moves downward, and the fluid in the pump chamber (9) is flowed out by one-way valve (10).When stopping heating, the gas cooling in the air chamber, volume-diminished, film (8) resilience makes fluid pass through one-way valve (11) and enters pump chamber (9), even so circulation heating, cooling pump are constantly worked.

Fig. 2 is a German Fraunholer research institute electrostatically actuated membrane pump structural drawing.This pump is by a glass sheet (12), and three silicon chips (13,14,15) are formed.Utilize the work of electrostatically actuated principle.Glass sheet (12) and silicon chip (13) have a dielectric spacer layer (16) betwixt as electrode, have pump chamber (17) on the silicon chip (13), have one-way valve (18,19) on the silicon chip (14,15).On glass sheet (12) and silicon chip (13), alternately add electric field during work, make it to produce the electric field of inhaling mutually or repelling each other, this electric field forces the film movement of silicon chip (13), when electric field repels each other, when film moved downward, the fluid in the pump chamber (17) was promptly discharged by one-way valve (18), when electric field when inhaling mutually, film moves upward, and promptly enters fluid by one-way valve (19) in the pump chamber (17).Fig. 3 is the structural drawing of the piezoelectric actuated membrane pump of northeastern Japan university, and this pump is made up of two blocks of glass sheet (20,21), a slice silicon chip (22), a piezoelectric crystal (23).Utilize piezoelectric actuated principle work.Accompany silicon chip (22) between the two sheet glass sheets (20,21), pump chamber (24) is arranged on the silicon chip (22), a film (25) is arranged on the glass sheet (20) and contact with piezoelectric crystal (23).Piezoelectric crystal during work (23) compressing film (25) moves downward, and forces the fluid in the pump chamber (24) to flow out through one-way valve (27), during the piezoelectric crystal outage, and film (25) resilience, fluid enters so periodic duty of pump chamber (24) through one-way valve (26).

Above-mentioned several micropump is owing to need the polylith element to form, so volume is bigger, complex structure assemble difficulty, and driving voltage is generally higher.

The purpose of this invention is to provide a kind of simple in structure, the micropump that driving voltage is low.

Micropump of the present invention utilizes the work of double-metal layer thermal actuation principle, is made up of two silicon thin film sheets, and etching has pump chamber on the silicon thin film sheet, fluid channel and one-way valve, and by the double-metal layer of forming by silicon thin film, aluminium film.Between silicon thin film, aluminium film, heating element is arranged, when heating element is switched on, the bimetallic strip action, make pump chamber become big, fluid enters pump chamber by one-way valve, after stopping to switch on, bimetallic strip returns to original state diminishes pump chamber, and force fluid flows out by another one-way valve.

The preparation process of micropump silicon thin film sheet of the present invention is as follows:

1. at first on twin polishing N type (100) silicon chip, two-sided thermal oxide growth 8000 SiO ₂, the Si of low-pressure chemical vapor phase deposition (LPCVD) 1500 ₃N ₄, this double-layer films as body silicon incorgruous corrosion cover the wall film.(Fig. 4 a)

2. photoetching is carried out in the front, and plasma etching goes out the corrosion window of valve port, uses KOH solution (40%) to carry out incorgruous corrosion, and the degree of depth is 30 μ m.(Fig. 4 b)

3. dual surface lithography is carried out at the back side, and plasma etching forms the pump chamber corrosion window, for the second time bulk silicon etching to the pump chamber single crystal silicon thickness 10 μ m, this moment the only remaining SiO in valve port place ₂And Si ₃N ₄Film, they will be as the support film of subsequent technique.(Fig. 4 c)

4. phosphorus is expanded in hypoxemia deposit overleaf, and thickness is the SiO of 1.5 μ m ₂, as sacrificial layer material; Two-sided deposit 2 μ m thick polysilicons expand phosphorus, and concentration is R =20 Ω/, residual stress is removed in annealing, positive photoetching, plasma etching forms the heating resistor that drives film; Back side photoetching, etching forms the one-way valve diaphragm, carries out sacrifice layer corrosion in the HF buffer solution, the relief valve diaphragm.(Fig. 4 d)

5. at front low-pressure chemical vapor phase deposition (LPCVD) deposit Si ₃N ₄, thick 1000 , photoetching and plasma etching form isolation layer.(Fig. 4 e)

6. positive vacuum evaporation aluminium film, thickness are 5 μ m, photoetching, and corrosion aluminium forms double-metal layer and contact conductor.(Fig. 4 f)

The preparation process of following sheet to last slice similar, different is increases a photoetching in order to form fluid channel, in addition, drives film and one-way valve diaphragm and is positioned at one side.After two silicon wafer to manufacture were finished up and down, the bonding glass pipe at the entrance and exit place was bonded two silicon chips at last and is assembled into a complete pump housing respectively.

Illustrate that accompanying drawing is as follows:

Fig. 1 is the moving membrane pump structural drawing of Dutch Twente university's hot gas.

Fig. 2 is a German franuhofer research institute electrostatically actuated membrane pump structural drawing.

Fig. 3 is the piezoelectric actuated membrane pump structural drawing of northeastern Japan university.

Fig. 4 is a silicon microheating actuating pump structural drawing of the present invention.

Fig. 5 micropump silicon thin film of the present invention preparation process procedure chart.

Accompanying drawings embodiment is as follows:

Silicon microheating actuating pump of the present invention (Fig. 4) is by two silicon thin film sheets (28,29) form, go up at last silicon chip (28) and be shaped on pump chamber (30) and one-way valve (31), fluid channel (32) with etching, at the silicon chip skin, the corresponding position of pump chamber (30) is shaped on silicon, Al bimetal layer (35), and (concrete technology is seen before and stated the preparation process part) gone up to remove at lower silicon slice (29) and is shaped on pump chamber (30), one-way valve (33), outside fluid channel (34) double-metal layer (36), also be shaped on fluid channel (37,38).With bond together after the assembling of upper and lower two silicon chips silicon microheating actuating pump of the present invention.During work, heater element (39) heating power in the double-metal layer (35,36), make upwards distortion of silicon thin film, make pump chamber (30) become big, so fluid promptly enter pump chamber (30) by raceway groove (32) one-way valve (31) raceway groove (37), after stopping to switch on, bimetallic strip (35,36) set back, pump chamber (30) dwindles, so fluid is promptly by raceway groove (38,34), one-way valve (33) is discharged.Work so repeatedly.The concrete size of this micropump can be:

Pump chamber size: 3mm * 3mm * 0.7mm one-way valve outlet: 0.1mm * 0.1mm

Double-metal layer thickness: aluminium film 5 μ m monocrystalline silicon membranes 10 μ m

Input power: 0.45w operating voltage: 0-50V

Frequency: 0-10Hz electric current: 100mA

Driver resistance: 450 Ω

This silicon microheating actuating pump is owing to adopt double-metal layer thermal actuation mode, the double-side driving structure, so active force is big, driving voltage is low, simple in structure, be easy to integrated, easily manufactured.

Claims

1, a kind of silicon microheating actuating pump, it is characterized in that with the work of double-metal layer thermal actuation principle, form by two silicon thin film sheets, etching has pump chamber on the silicon thin film sheet, fluid channel and one-way valve, and have by monocrystalline silicon thin film, the double-metal layer that the aluminium film is formed has heating element between monocrystalline silicon thin film and aluminium film.

2, the manufacturing process of the used silicon thin film of a kind of silicon microheating actuating pump is characterized in that being made up of following operation,

＜1.〉and at first on twin polishing N type (100) silicon chip, two-sided thermal oxide growth 8000 SiO ₂, the Si of low-pressure chemical vapor phase deposition (LPCVD) 1500 ₃N ₄, this double-layer films as body silicon incorgruous corrosion cover the wall film.

＜2.〉front carries out photoetching, plasma etching goes out the corrosion window of valve port, uses KOH solution (40%) to carry out incorgruous corrosion, and the degree of depth is 30 μ m.

＜3. the back side carries out dual surface lithography, plasma etching forms the pump chamber corrosion window, for the second time bulk silicon etching to the pump chamber single crystal silicon thickness 10 μ m, this moment the only remaining SiO in valve port place ₂And Si ₃N ₄Film, they will be as the support film of subsequent technique.

＜4.〉hypoxemia deposit overleaf, expanding phosphorus, thickness is the SiO of 1.5 μ m ₂, as sacrificial layer material; Two-sided deposit 2 μ m thick polysilicons expand phosphorus, and concentration is R =20 Ω/, residual stress is removed in annealing, positive photoetching, plasma etching forms the heating resistor that drives film;

Back side photoetching, etching forms the one-way valve diaphragm, carries out sacrifice layer corrosion relief valve diaphragm in the HF buffer solution.

＜5.〉at front low-pressure chemical vapor phase deposition (LPCVD) deposit Si ₃N ₄, thick 1000A, photoetching and plasma etching form isolation layer.

＜6.〉positive vacuum evaporation aluminium film, thickness is 5 μ m, photoetching, and corrosion aluminium forms double-metal layer and contact conductor.