CN101255859B - Subtense wimble structure micro-driver driven by titanium adnic alloy membrana as well as preparing method - Google Patents

Abstract

A chord-cone structure micro-actuator driven by a ternary titanium-nickel-copper shape memory alloy film and its preparation method. The shape memory alloy drive film is deposited by sputtering, and the MEMS process is used to complete the strip resistance design. The upper and lower body structures of the micro-driver are prepared by Si etching process, and realize bonding welding. The body (2) and the lower body (3) are processed into a drive cavity (4) with a pressure pump function; the lower body (3) is made into a valve body expansion tube with a one-way valve while processing the drive cavity (4) (5) and shrinkage tube (6); described valve body expansion tube and shrinkage tube are respectively aligned with water inlet pipe (7) and water outlet pipe (8) and connected, and ternary TiNiCu is housed on the described chord-cone structure micro-actuator /Si shape memory alloy driving thin film (1). The invention can be widely used in the fields of fluid microtransmission, integrated system cooling, microchemical analysis and the like.

Description

String-cone structure micro-actuator driven by titanium-nickel-copper alloy film and preparation method

Technical field:

The invention relates to an executive device of a MEMS microfluidic system, in particular to a string-cone structure micro-drive driven by a ternary TiNiCu shape-memory alloy film and a preparation method thereof. the

Background technique:

As the executive device of MEMS microfluidic system, micro-actuator is an important symbol of the development level of microfluidic system. It is widely used in drug micro-delivery, fuel micro-injection, cell separation, integrated electronic cooling, and micro-chemical analysis. Therefore, the research on micro-actuators has always been a focus of micro-machining systems, and it is also the main bottleneck of the practical application of micro-fluidic systems. Since the flow output of the micro-actuator is realized by the reciprocating motion of the driving membrane, which causes the volume and pressure of the pump chamber in the microsystem to change, the driving force of the driving membrane directly determines the performance index of the micro-actuator, that is, the degree of deformation of the driving membrane, Response frequency has a crucial influence on the operation of micro-drives. At present, the driving forms of the driving membrane include shape memory effect driving, piezoelectric, electrostatic, electromagnetic, thermopneumatic, thermal flow and bimetallic effect, etc. Among them, thermopneumatic and bimetallic effects belong to low-frequency drives, and their disadvantage is that the driving flow is small; piezoelectric ceramics, electrostatics, and electromagnetics belong to high-frequency drives. Although the flow is relatively large, the disadvantage is that the required operating voltage is correspondingly high. It is difficult to apply matching. For example, in the paper "Bimetal Thermally Actuated Micropump" published by Yang Yue, Zhou Zhaoying and Ye Xiongying of Tsinghua University in "Journal of Instrument and Apparatus" in 1996, the bimetallic drive micropump they developed has a driving voltage of 20V, the driving frequency is only 5Hz, and the output flow rate is 36μl/min. In "Micro ElectroMechanical Systems", R.Zengerle and A.Richter of Fraunhofer Institute for Solid Technology (IFT) published the paper "A micro membrane pump with electrostatic actuation" in 1992. The reported electrostatically driven micropump has a high operating voltage. It is 170V, which is not conducive to the application. Shape memory alloys have become the preferred driving materials for micro-actuating devices in recent years because of their good driving characteristics. For example, in the journal "Sensors and Actuators", the paper "Characteristics and fabrication of NiTi/Sidiaphragm micropump" published by Xu Dong of Shanghai Jiaotong University and others in 2001 reported a binary TiNi shape memory alloy driven micropump with an output flow of 340ml /min. However, the phase transition point of the binary TiNi alloy is greatly affected by the composition, and the yield in the preparation process is low; at the same time, the phase transition temperatures of martensite and austenite are about 25° and 75°, respectively, and the phase transition hysteresis is relatively large (ΔT ≤50℃), resulting in a lower driving frequency, which limits the application. the

Invention content:

The purpose of the present invention is to provide a preparation method of a TiNiCu/Si shape memory alloy driving film, the design and manufacture of a chordal-cone structure micropump, and the use of a ternary TiNiCu shape memory alloy film for good driving of the micropump by the shape memory alloy film Actuated chord-cone microactuators. The shape memory alloy driving thin film is deposited on the upper body of the driver by sputtering, and the strip resistance design is completed to facilitate driving. The upper and lower body structures of the micro-driver are prepared by Si etching process and bonded and welded. The upper body 2, which acts as a pressure pump, and the lower body 3, which acts as a valve body, are processed into a drive chamber 4 with a pressure pump function; while the lower body 3 is processing the drive chamber 4, it is made into a valve body expansion tube 5 with a one-way valve and The shrink tube 6; the expansion tube and the shrink tube of the valve body are respectively aligned and connected with the water inlet pipe 7 and the water outlet pipe 8, and the string-cone structure micro-driver equipped with a ternary TiNiCu/Si shape memory alloy driving film 1 can be completed under the action of an electric current. Complete the driving function of the fluid. the

Above-mentioned purpose realizes by following technical scheme:

A chord-cone structure micro-actuator driven by a ternary TiNiCu shape memory alloy film. Its composition includes: an upper body that can function as a pressure pump and a lower body that can function as a valve body. The upper body and the lower body are processed to have a pressure pump Functional drive cavity; while the lower body is processing the drive cavity, it is made into a valve body expansion tube and a contraction tube with a one-way valve; the valve body expansion tube and contraction tube are opposite to the water inlet pipe and the water outlet pipe respectively quasi-connection, the ternary TiNiCu/Si shape-memory alloy drive film is installed on the chord-cone structure micro-driver. The aforementioned chord-cone structure micro-actuator driven by a ternary TiNiCu shape memory alloy film also includes an electrode for connecting to an external drive power supply and a TiNiCu alloy film resistance strip for generating driving pressure. the

The above-mentioned chord-cone structure micro-actuator driven by a ternary TiNiCu shape memory alloy film, the structure of the upper and lower bodies is prepared by silicon (Si) micromachining and silicon (Si) anisotropic etching process corrosion , and welded by bonding technology. the

The above-mentioned chordal-conical micro-actuator driven by a ternary TiNiCu shape memory alloy film, the expansion tube and the contraction tube are made by using an anisotropic etching process of silicon Si, and the size of the small end of the chordal-conical tube is 20 ~30μm, the taper is calibrated by the angle between the tangent line of the two walls of the chord-conical tube. The outer chord wall is tangent to the drive cavity wall; the tube length is 1800-2000 μm. the

The above-mentioned chordal-cone structure micro-actuator driven by a ternary TiNiCu shape memory alloy film, the drive cavity is obtained after corrosion by using an anisotropic etching process of silicon Si, and the thickness of the silicon film of the upper body drive cavity is 10 ~12 μm. the

The above-mentioned chord-cone structure micro-actuator driven by a ternary TiNiCu shape memory alloy film, the drive film adopts a TiNi target atomic percentage of Ti 55.4%, Ni44.6% and a pure copper target to be simultaneously sputtered at the same point, in a circle A driving thin film with a thickness of 30 μm is grown on the driving cavity of a silicon film, and annealed at 750°C for one hour. The copper content in the thin film is controlled by the sputtering voltage on the copper target. the

The above-mentioned chordal-cone structure micro-actuator driven by the ternary TiNiCu shape memory alloy film is used to pattern the driving film, and under the protection of the photoresist, the composition of the corrosive solution is: 15% by weight of HF, HNO ₃ The parts by weight of H ₂ O ₂ are 15%, the parts by weight of H 2 O 2 are 2%, and the parts by weight of H ₂ O are 68%. structure, the distance between resistor bars is 20-30 μm.

This technical solution has the following beneficial effects:

1. Due to the adoption of the above measures, the present invention has the characteristics of simple preparation process, high driving frequency, large output flow, strong flow controllability, low power consumption, long life, small volume and low cost compared with the prior art. In addition, the micromachining technology adopted in the present invention is compatible with semiconductor plane technology, and can be integrated with other micro-detection and micro-control elements and circuits, suitable for mass production, and can be widely used in the field of micro-flow systems, especially for Cooling of ultra-large integrated circuits and high-power components. the

2. Compared with other driving modes such as binary TiNi alloys, the TiNiCu/Si driving thin film of the present invention has the obvious advantage of high driving frequency, and can obtain larger output under the action of pulse driving current. Magnetron sputtering TiNiCu driving film is used as the driving material, which solves the problem of the bonding force between the material, the silicon-based film and the electrode, and does not cause peeling or cracking after tens of thousands of reciprocating movements. At the same time, it is compatible with the semiconductor planar process A good combination is conducive to integrated design and batch processing. the

3. The invention has the advantages of simple structure and process, small volume, strong controllability, large output flow and low power consumption, and can be widely used in various fields such as liquid microtransmission, cell separation and integrated system cooling. the

Description of drawings:

Accompanying drawing 1 is to adopt TiNiCu driving film to drive the side sectional structure schematic diagram of cone string micro-driver;

Accompanying drawing 2 is the top view structure schematic diagram of the ternary TiNiCu shape memory alloy driving film after etching;

Accompanying drawing 3 is A-A sectional view of accompanying drawing 1. the

Accompanying drawing 4 is the B-B sectional view of accompanying drawing 1, namely the top view structure schematic diagram of the liquid flow path of the chordal-cone structure micro-actuator. the

The specific embodiment of the present invention:

Example 1:

The composition of the present invention includes: the preparation of the ternary TiNiCu driving film and the production of the chordal pump, the ternary TiNiCu/Si shape memory alloy driving film 1 and the upper body 2 which can function as a pressure pump and the lower body 3 which can function as a valve body. Parts jointly complete the implementation process of the MEMS microfluidic system. Among them, the upper body 2 and the lower body 3 are processed into a driving chamber 4 with a pressure pump function; while the lower body 3 is processing the driving chamber 4, it is made into a valve body expansion tube 5 and a contraction tube 6 with a one-way valve; the expansion tube 5 and the contraction tube The pipe 6 is aligned with the water inlet pipe 7 and the water outlet pipe 8 respectively; as the driving film 1 driven by the shape memory effect, it adopts the form of a TiNiCu driving film, and its composition includes electrodes 9, 11 for connecting to an external driving power supply and A TiNiCu alloy thin film resistance strip 10 for generating driving pressure. the

The TiNiCu alloy thin film resistance strip 10, under the action of the driving power of the electrodes 9 and 11, uses the shape memory effect of the alloy thin film to produce shrinkage and stretching, and the TiNiCu driving film produces bending deformation, which causes the volume and pressure of the driving chamber 4 to change. The cooperation of the tube 5 and the shrink tube 6 forces the liquid to flow between the inlet and outlet pipes 7 and 8 . the

The working principle of the invention is to use the shape memory effect of the TiNiCu driving film 1. When the current is applied to the shape memory alloy resistance strip, the ohmic heat generated will make the shape memory alloy phase transform from martensite phase to austenite phase, and the alloy The deformation generates the driving membrane to move upwards, so that the pressure in the driving cavity 4 with the pressure pump function decreases, and the expansion tube 5 is separated from the water inlet pipe by the difference in the pressure loss coefficient of the two expansion tubes 5 and the contraction tube 6 under the micro size. 7 Inhale the liquid; on the contrary, when the square wave driving current is withdrawn, the temperature of the shape memory alloy decreases, and the alloy phase changes from austenite to martensite to restore its shape, driving the film 1 and the upper body 2 to move downward, and driving the cavity 4 As the internal pressure increases, the shrink tube 6 discharges the liquid toward the water outlet pipe 8 in a directional manner. Therefore, as the TiNiCu-driven membrane 1 and the upper body 2 move periodically under the action of the square wave electric signal, the liquid is continuously drawn through the water inlet pipe 7. It is drawn in and pumped out through the outlet pipe 8 . The flow range of the micro-driver of the invention can be adjusted according to the different needs of different users, through the TiNiCu drive film 1 and shrinkage

The size design of the tubes and expansion tubes 5 and 6 is determined. When the design size is determined, the flow rate of the micro-driver can be further adjusted by changing the current and frequency applied to the TiNiCu drive film 1 within a certain fine-tuning range. . the

Example 2:

The preparation method of the present invention is as follows:

，其中x≤5％；合金薄膜奥氏体与马氏体之间相转变迟滞温度ΔT≤25°，以实现薄膜具有较高的驱动频率。为实现电驱动，对制备的薄膜进行图形化处理，在光刻胶的保护下利用腐蚀液(成分为：HF(15％)/HNO₃(15％)/H₂O₂ (2％)/H₂O(68％))将薄膜刻蚀成为厚30μm、宽70-80μm的环状电阻条，电阻条间距为20-30μm。  The preparation of TiNiCu/Si driving thin film is completed by magnetron sputtering process. Using a TiNi target whose atomic percentage is Ti 55.4%, Ni44.6% and a pure copper target to be sputtered at the same time at the same time, a driving film with a thickness of 30 μm is grown on a circular silicon film driving chamber, and the copper content in the film is controlled by the copper target Controlled by the sputtering voltage, annealed at 750 °C for one hour to obtain the martensitic structure phase. In order to realize that the film has a good driving ability, the prepared film should have: the elements of Ti, Ni, and Cu are evenly distributed, and the atomic percentages are Ti 50%, Ni(44±x)%,

, where x≤5%; the phase transition hysteresis temperature ΔT≤25° between austenite and martensite in the alloy film, so as to realize the high driving frequency of the film. In order to realize electrical driving, the prepared thin film is patterned, and under the protection of the photoresist, an etching solution (composition: HF (15%)/HNO ₃ (15%)/H ₂ O ₂ (2%)/ H ₂ O (68%)) etch the thin film into ring-shaped resistance strips with a thickness of 30 μm and a width of 70-80 μm, and the distance between the resistance strips is 20-30 μm.

The driving cavity 4 of the upper body 2 is made by etching on the reverse side of the semiconductor [100] silicon (Si) sheet, and adopts the anisotropic etching process in the micromachining process to the required silicon (Si) film thickness of 10 ~ 12 μm, forming the expansion tube and contraction tube 5, 6 of the lower body 3 of the circular drive chamber 4 are also made by silicon (Si) micromachining, and the shape of the conical tube is formed through an etching process, and the small opening of the conical tube The size of the end is 20-30μm, and its taper is calibrated by the angle between the tangent line of the two walls of the chord-conical tube. Radian, the outer chord wall of the tube wall is tangent to the drive cavity wall; the tube length is 1800-2000 μm. Process the inlet and outlet pipes 7 and 8 with the same process, and the diameter of the pipes is generally 1000 μm. The bonding between the upper body 2 and the lower body 3 adopts Si-Au-Si bonding technology, and a layer of Au metal film is coated on the front side of the lower body 3, and then only the metal film on the part that needs to be bonded is treated by photolithography and chemical etching. It is preserved, and the rest is etched away. Finally, the upper and lower bodies 2 and 3 are aligned, and then put into the sintering furnace to reach the eutectic temperature, then welding and bonding can be performed. the

Example 3:

The overall external dimension of the present invention is 12mm * 8mm * 3mm, wherein the TiNiCu/Si drive thin film 1 A circular strip with a thickness of 30 μm and a maximum diameter of 4 mm, lead electrodes 9 and 11 at the junctions of the two ends of the TiNiCu/Si driving film 1, are used to connect with the driving power, the driving power adopts a square wave, and the working voltage is 5V. The frequency range is 30~120Hz. the

When the micro-driver is used for microtransmission of fluid, the liquid which has no chemical reaction with silicon is connected to the water inlet pipe 7, and the water outlet pipe 8 is connected to the liquid collecting end. Under the action of the driving power, the TiNiCu/Si driving film 1 changes the volume of the driving chamber 4, so that there is a pressure difference between the inside and outside of the pump. The liquid is continuously pumped in through the water inlet pipe 7, and then pumped out through the water outlet pipe 8, finally achieving the purpose of liquid delivery and control by the micro-driver. the

The manufacturing process of TiNiCu/Si driving thin film 1 is:

，其中x≤5％；  A TiNi target (Ti 55.4%, Ni 44.6%) and a pure copper target are sputtered at the same time at the same time, and a driving film with a thickness of 30 μm is grown on a circular silicon film driving cavity, and the copper content in the film is controlled by The sputtering voltage on the copper target is controlled. Anneal at 750°C for one hour. The prepared film should have: Ti, Ni, Cu elements are evenly distributed, and the atomic percentages are Ti 50%, Ni(44±x)%,

, where x≤5%;

Under the protection _{of photoresist} , _the film _is etched into thick Ring resistance strips 10 with a width of 30 μm and a width of 70-80 μm and pins 9 and 11 of the resistance strips, the distance between the resistance strips is 20-30 μm. Under the condition of mask protection, the aluminum film is prepared by vacuum evaporation on the pin of the resistance strip, and then the outer lead is connected.

The driving cavity 4 of the upper body 2 and the structure of the lower body 3 are made by etching silicon anisotropically. The bonding between the upper body [1] and the lower body [2] with the same driving cavity structure adopts Si-Au-Si bonding, Au is plated on the front side of the lower body 2 with a film thickness of 1 μm, and then photolithography and chemical etching are used to Only the metal film in the bonding area is reserved, and the rest are etched away. Finally, the upper and lower bodies 1 and 2 are aligned, placed in a sintering furnace at a temperature of 650° C., and then bonded. the

Claims (6)

1. A chord-cone structure micro-actuator driven by a ternary titanium-nickel-copper shape memory alloy film, its composition includes: the lower body that can play the upper body of the pressure pump effect and the valve body effect, is characterized in that: the described upper body The body and the lower body are processed into a drive cavity with the function of a pressure pump; while the lower body is processing the drive cavity, it is made into a valve body expansion tube and a contraction tube with a one-way valve function; the valve body expansion tube and contraction tube They are aligned and connected with the water inlet pipe and the water outlet pipe respectively, and the ternary TiNiCu/Si shape memory alloy driving film is installed on the chord-cone structure micro-actuator. 2. The chordal-cone structure micro-actuator driven by a ternary titanium-nickel-copper shape memory alloy film according to claim 1, characterized in that: the ternary TiNiCu/Si shape memory alloy drive film includes a The electrodes of the driving power supply and the TiNiCu alloy film resistance strips used to generate the driving pressure. 3. According to claim 1 or 2, the chordal-cone structure micro-actuator driven by the ternary titanium-nickel-copper shape memory alloy film is characterized in that: the structure of the upper and lower bodies adopts micromachining of silicon and passes through silicon It is prepared after corrosion by anisotropic etching process, and welded and shaped by bonding technology. 4. The chordal-cone structure micro-actuator driven by a ternary titanium-nickel-copper shape memory alloy film according to claim 1 or 2, characterized in that: the expansion tube and the contraction tube are anisotropic etching processes using silicon Made, the size of the small mouth end of the conical tube of the expansion tube and the contraction tube is 20 ~ 30 μm, the taper of the conical tube is calibrated by the angle between the chord tangent of the two walls of the conical tube, and the taper value is 10° ~15°, the arc of the tube wall chord is the arc determined by the diameter of 4~5 times the diameter of the driving cavity, and the outer chord wall of the tube wall is tangent to the driving cavity wall; the tube length is 1800~2000μm. 5. The chordal-cone structure micro-driver driven by a ternary titanium-nickel-copper shape memory alloy film according to claim 1 or 2, characterized in that: the drive cavity is corroded by an anisotropic etching process of silicon Obtained later, the thickness of the silicon film of the upper body driving cavity is 10-12 μm. 6. The chordal-cone structure micro-actuator driven by a ternary titanium-nickel-copper shape memory alloy film according to claim 3, characterized in that: the drive film is made of Ti 55.4% and Ni 44.6% by atomic percentage. The TiNi target and the pure copper target are sputtered at the same time, and a driving film with a thickness of 30 μm is grown on a circular silicon film driving cavity, and annealed at 750 ° C for one hour. The copper content in the film is controlled by sputtering on the copper target. voltage to control.

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