TWI584779B - Hexagonal-type micro sensing probe and method for fabricating the same - Google Patents

Description

Hexagonal cylinder miniature sensing probe and preparation method thereof

The present invention relates to miniature sensing probes, and more particularly to a hexagonal cylindrical microsensing probe that senses acid and alkali and temperature.

Micromechanical sensing probes have been developed and widely used for biomedical purposes. These sensing probes provide different application functions from micro-heating to fluid delivery. Usually these sensing probes can penetrate the muscle tissue of the human body without It can cause severe wounds and provide relevant data for sensing. Therefore, the micro-scale, intensity and functionality of the sensing probe have attracted a lot of attention from many researchers.

Micromechanical sensing probes are used in medicine. For example, during heart transplantation, the heart temperature must be kept within the range of 15 to 30 °C to prevent myocardial necrosis of the heart, so the heart in an in vitro environment should be preserved. In an incubator filled with ice. However, due to the temperature gradient in the myocardium, the deeper the part of the myocardium has a higher temperature than the surface of the heart, because the temperature of the myocardium cannot be directly measured by the open-heart operation, the heart of the wrong cause Myocardial necrosis may occur due to temperature monitoring. In addition, in previous studies, it was found that the damage of the heart sarcolemma may be related to the muscle The pH of the meat is related because muscle perfusion causes a large influx of calcium into the heart muscle cells during hypoxia, all of which may affect the chances of successful heart transplant surgery. Therefore, finding robust and slender probes for monitoring the temperature and pH of heart muscles at different locations has been an important research topic for heart transplants, and biomedical sensory probes are a good choice. The advantage is that this technology has been developed for many years, and such sensing probes have good biocompatibility, only minimal tissue trauma through penetration, and can have many sensing functions, such as from micro-heating to fluid transport. Wait.

Therefore, how to develop a miniature sensing probe, especially in cardiac surgery, can instantly monitor the heart temperature and pH value, not only has a strong and slender structure and good biocompatibility, but also has a simple probe. The needle process program has become the goal pursued by those skilled in the art.

In view of the above-mentioned shortcomings of the prior art, it is an object of the present invention to provide a miniature sensing probe which is manufactured by a simple process technology to produce a robust and slim micro-sensing probe with both temperature sensing and acid-base sensing. Features.

To achieve the foregoing and other objects, the present invention provides a hexagonal cylindrical miniature sensing probe comprising: a thermal probe assembly and a pH probe assembly. The cross section of the thermal probe assembly is trapezoidal, and the short bottom edge of the thermal probe assembly has two sensing regions formed by the heat sensing material, wherein one sensing region is used for sensing the temperature of the object to be tested. The other sensing area is used for sensing the ambient temperature, the cross-section of the PH probe component is trapezoidal, and the short bottom edge of the PH probe component is formed with two PH-sensing materials. Sensing film a region, wherein a long bottom edge of the thermal probe assembly is bonded to a long bottom edge of the pH probe assembly such that a cross section of the hexagonal cylindrical micro-sensing probe exhibits a hexagonal cylinder shape.

In one embodiment, the thermal probe assembly and the pH probe assembly are etched by potassium hydroxide to form a structure having a trapezoidal cross section.

In another embodiment, the thermal sensing material comprises copper or platinum formed by electroplating or polycrystalline germanium formed by electroless plating.

In still another embodiment, the pH sensing material is silver/silver chloride and yttrium oxide, or is composed of an ion-sensing field effect transistor.

The invention also provides a method for manufacturing a hexagonal cylinder micro-sensing probe, comprising the steps of: forming two sensing regions composed of a thermal sensing material on a first probe base wafer, and using potassium hydroxide KOH silicon etching a part of the substrate of the probe base wafer to form a thermal probe, and forming a second sensing thin film region formed by the pH sensing material on a second probe base wafer, and utilizing Potassium hydroxide 矽 etching a portion of the substrate of the second probe base wafer to form a pH probe; and combining the thermal probe and the pH probe with an adhesive material to form a miniature sensing probe having a hexagonal cylinder .

In one embodiment, the processes of the first and second probe base wafers include: forming a deposited layer comprising oxides and nitrides by chemical vapor deposition on a substrate; defining a probe pattern on the deposited layer And etching the patterned deposited layer by reactive ion etching; and coating the photoresist on the deposited layer to complete the etching to define a conductive pad and a conductive line, and forming a copper layer and nickel on the deposited layer. a gold layer to form the first and second probes Base wafer.

In one embodiment, the copper layer is formed by electroplating, and the nickel/gold layer is formed by electroless plating.

In another embodiment, the pH sensing material is silver/silver chloride and cerium oxide, and the silver/silver chloride and the cerium oxide form a silver/silver chloride layer and oxidize on the nickel/gold layer. In the ruthenium layer, the silver/silver chloride layer is formed by coating a photoresist material to define a silver chloride pad and sputtering silver on a silver chloride pad, and the ruthenium oxide layer is formed by electroplating.

Compared with the prior art, the hexagonal column micro-sensing probe of the present invention can instantly sense the temperature of the object to be tested through a heat sensing material such as a thermal induction coil and a pH sensing material such as a PH sensing electrode. PH value, and the micro-sensing probe not only has good biocompatibility, but also the structure of the hexagonal cylinder can enhance its penetration force and compressive buckle force, and it is easier to penetrate the object to be tested, for example Myocardium or human and animal tissue. Furthermore, the process is a CMOS compatible program and can be easily integrated with existing CMOS chips. Therefore, the hexagonal column micro-sensing probe of the present invention is not only highly functional and easy to process, but also greatly contributes to the development of the micro-sensing probe.

1‧‧‧Hexagon cylinder miniature sensing probe

11‧‧‧Hot probe assembly

111‧‧‧ copper coil

112‧‧‧Upper sensing area

113‧‧‧Down sensing area

12‧‧‧PH value probe assembly

121‧‧‧Oxide

122‧‧‧Silver/silver chloride

S301~S306‧‧‧Steps

401‧‧‧Substrate

402‧‧‧Oxide layer

403‧‧‧ nitride layer

404‧‧‧ copper layer

405‧‧‧ Nickel/gold layer

406‧‧‧ tin layer

407‧‧‧Silver/silver chloride layer

408‧‧‧Oxide layer

409‧‧‧Adhesive layer

1 is a schematic structural view of a hexagonal column micro-sensing probe of the present invention; FIGS. 2A and 2B are a hexagonal column appearance view of a hexagonal column micro-sensing probe of the present invention; FIG. 3 is a view of the present invention; Method for manufacturing hexagonal cylinder miniature sensing probe FIG. 4A-4G is a process flow diagram of the hexagonal cylinder micro-sensing probe of the present invention; FIG. 5 is a temperature test diagram of the hexagonal cylinder micro-sensing probe of the present invention; FIG. The pressure test chart of the hexagonal column micro-sensing probe of the present invention is shown; and the figure 7 shows the PH test chart of the hexagonal column micro-sensing probe of the present invention.

The embodiments of the present invention are described below by way of specific examples, and those skilled in the art can readily understand other features and functions of the present invention from the disclosure herein. The invention may also be embodied or applied by other different embodiments.

Referring to Fig. 1, there is shown a schematic structural view of a hexagonal column micro-sensing probe of the present invention. As shown, the hexagonal cylindrical micro-sensing probe 1 includes a thermal probe assembly 11 and a pH probe assembly 12 that provide temperature sensing and acid-base pH sensing of the analyte, respectively.

In the appearance structure, the cross section of the thermal probe assembly 11 is trapezoidal, and the short bottom edge of the thermal probe assembly 11 has two upper sensing regions 112 and lower sensing regions 113 formed of thermal sensing materials. In the sensing region, the heat sensing material may be a copper coil 111 formed by electroplating, wherein the lower sensing region 113 is used to sense the temperature of the object to be tested, and the upper sensing region 112 is used to sense the environment. temperature. It should be noted that the present invention is not limited to the use of the copper coil 111. The sensing temperature can be replaced by other thermal sensing materials having the same function, such as platinum which is also formed by electroplating, or polycrystalline silicon formed by electroless plating. Therefore, thermocouple, thermistor And the resistance temperature detector (RTD) and the like are commonly used thermal sensing mechanisms.

In the appearance structure, the cross-section of the PH probe assembly 12 is also trapezoidal, and the two short sensing edges of the pH probe assembly 12 are formed with two sensing film regions formed by the pH sensing material. The pH sensing material may be yttrium oxide (IrO _x ) 121 and silver/silver chloride (Ag/AgCl) 122 forming two sensing film regions, but not limited thereto, for example, using an ion sensing field. The ion sensitive field effect transistor (ISFET) is used to replace the pH sensing material, and the pH sensing purpose can also be achieved. In addition, the PH glass electrode or the optical fiber pH sensor (optical fiber pH sensor) ) is also often used as a pH sensing structure.

The long bottom edge of the thermal probe assembly 11 is joined to the long bottom edge of the pH probe assembly 12 such that the cross-section of the hexagonal cylindrical micro-sensing probe 1 is hexagonal.

Specifically, the hexagonal cylindrical micro-sensing probe 1 is composed of a thermal probe assembly 11 and a pH probe assembly 12, and the thermal probe assembly 11 and the pH probe assembly 12 can be respectively designed to have a length of 6 mm and a 5.3 mm wide tail, and a body 10 mm long and 0.7 mm wide, which are bonded together in a back-to-back manner, in particular using a potassium hydroxide (KOH) etching method to make the hexagonal column The body miniature sensing probe 1 forms a hexagonal cylinder which will help penetrate the object to be tested.

In one embodiment, the thermal probe assembly 11 has two sensing regions, and the upper sensing region 112 near the tail of the thermal probe assembly 11 is used to sense room temperature while away from the tail of the thermal probe assembly 11. The lower sensing region 113 is used to sense the temperature of the object to be tested, wherein the mechanism of the thermal sensing is a metal resistance, which will change linearly with temperature. Considering the size limitation of the thermal probe assembly 11, only a 15 ohm copper coil is used. Among them, the reason why copper is selected as the sensing material includes that copper has a good temperature coefficient, and copper plating is also a convenient and stable general process.

In addition, in the pH probe assembly 12, the two sensing film regions formed by the yttrium oxide 121 and the silver/silver chloride 122 can be respectively designed to have a size of 600 mm × 200 mm, wherein the yttrium oxide 121 is used as The pH of the sensing electrode, and the silver/silver chloride 122 is the reference electrode for the pH value. The Nernstian equation is shown below:

Wherein F is expressed as a Faraday constant having a value of about 96500 C/mole, R is a gas constant, and its value is 8.314 J/mole K, and E ⁰ is a standard potential of silver chloride, and its value is 577 mV. After sensing the charging of the thin film electrode, the Nernst response will show a pH sensitivity of -59 mV/pH at 25 ° C. After the pH sensing film is fabricated, the pH can be determined by an open circuit method.

As can be seen from the above, the hexagonal cylinder micro-sensing probe 1 can be formed by the composition of the thermal probe assembly 11 and the pH probe assembly 12, and the hexagonal cylinder shape is as shown in FIGS. 2A and 2B, and the second The picture shows a side view of a hexagonal cylinder miniature sensing probe, and Figure 2B shows a hexagonal cylinder miniature sensing probe. A 45 degree angle view.

Referring to FIG. 3, which is a step diagram illustrating a method of manufacturing a hexagonal column micro-sensing probe of the present invention, and FIG. 4A-4G is a flow chart showing a process of manufacturing the hexagonal column micro-sensing probe of the present invention. . Next, the process steps of the method for manufacturing a hexagonal cylindrical micro-sensing probe of the present invention will be described with reference to FIG. 3 and FIG. 4A-4G.

It should be noted that the core of the present invention is to combine the thermal probe and the pH probe of the ladder structure formed by the etching of potassium hydroxide, so that the process of forming the thermal probe and the pH probe is not the focus of the present invention. However, in order to demonstrate that the present invention has the advantage of being easy to process, the following process steps are still started with the most basic probe processes, and in this process step, copper coils are selected as the thermal sensing material and yttrium oxide and silver are selected. / Silver chloride is a PH sensing material as an example.

In step S301, a deposited layer containing an oxide and a nitride is formed on the substrate by a chemical vapor deposition technique. Referring to FIG. 4A, the substrate 401 may be an oxide layer 402 formed on the substrate 401 by an oxidizing furnace and a low pressure chemical vapor deposition system (LPCVD) using a <100>-orient, standard doping, and a 250 μm thick germanium wafer. The deposited layer of the nitride layer 403 has a thickness of about 6000 Å and 7000 Å, respectively, wherein the nitride layer 403 can serve as a protective layer to avoid etching of the substrate 401 by potassium hydroxide. Next, the process goes to step S302.

In step S302, a probe pattern is defined on the deposited layer, and the patterned deposited layer is etched by reactive ion etching. In this step, a 5 μm thick photoresist material AZ4620 can be applied to define the probe pattern. And etching the patterned oxide layer 402 and the nitride layer 403 by a dielectric material reactive ion etching system, after ion etching the oxide layer 402 and the nitride layer 403, removing the photoresist material AZ4620 through the ACE Form a structure as shown in Fig. 4A. Next, the process goes to step S303.

In step S303, a photoresist material is coated on the deposited layer to complete etching to define a conductive pad and a conductive line, and a copper layer and a nickel/gold layer are formed on the deposited layer to form first and second probes. Base wafer. Please cooperate with Figure 4B to apply a photoresist material on the deposited layer before the etching to define the conductive pads and conductive lines. Specifically, the titanium/copper layer can be first sputtered as a seed layer, and then 1 μm thick. A copper layer 404 is formed, and a 0.5 μm thick nickel/gold layer 405 is formed by electroless plating, wherein the nickel/gold layer is used to prevent oxidation of copper.

Up to the present step, the probe base wafer can be formed, that is, it can be shared by the thermal probe component and the pH probe component, and then the subsequent processes can be continued according to the respective requirements of the thermal probe and the pH probe. Next, the process goes to step S304.

In step S304, a tin layer is formed on the nickel/gold layer in the first probe base wafer, and a portion of the substrate of the first probe base wafer is etched to form a thermal probe. Please select the first probe base wafer in conjunction with the 4C and 4D drawings, and form a tin layer 406 on a portion of the nickel/gold layer 405 of the first probe base wafer, and then etch the first probe base wafer by potassium hydroxide. Part of the substrate, thus completing the thermal probe. Next, the process goes to step S305.

In step S305, in the second probe base wafer, a silver/silver chloride layer and a ruthenium oxide layer are formed on the nickel/gold layer, and a part of the substrate of the second probe base wafer is etched to form a pH value. needle. Please select the second probe base wafer according to the 4E and 4F drawings, and form a silver/silver chloride layer 407 and a yttrium oxide layer 408 on the nickel/gold layer 405. Specifically, the yttrium oxide layer 408 can be circulated. Formed by a cyclic voltammetry electroplating method, the cerium oxide plating solution of the method comprises 0.75 mg of IrCl ₄ dissolved in 50 mL of water, and then the solution is stirred for 15 minutes, and 0.5 ml of 30% hydrogen peroxide (H ₂ O _{2 is added).} And the solution was stirred for another 10 minutes, 250 mg of sodium oxalate (Na ₂ C ₂ O ₄ ) was added, and the solution was stirred for another 10 minutes, and a small portion of 1 M K ₂ CO ₃ was added to the solution until the pH was 10.5. After 2 days of stabilization, the solution was allowed to stand for 2 days.

In addition, the electrochemical experiment was carried out by three electrode battery systems, silver/silver chloride as a reference electrode, platinum foil as a contrast electrode, and a gold layer of a pH probe as a working electrode. Cyclic voltammetry plating method, from 0V to 0.6V for silver chloride at a rate of 20mV / s for 280 cycles, after silver chloride plating, the completed wafer is bathed in a pH 7 buffer solution to stabilize The potential of silver chloride.

Next, a photoresist material is applied to define the area of the silver chloride pad, then 100 nm thick silver is sputtered onto the wafer, using a lift off method with ACE and ultra sound, and in silver chloride The pad was left with a silver film, and the silver chloride was hydrogenated in a 50 mM FeCl ₃ solution for 20 seconds, and then the wafer was immersed in a 3 M KCL solution to stabilize the potential of silver chloride.

Similarly, a portion of the substrate of the probe base wafer is etched by potassium hydroxide, thus completing the thermal probe, wherein the seed layer can be easily removed by copper etching before the potassium hydroxide etching. In addition, step S304 and The thermal probe and the pH probe formed by S305 have no front-to-back order. Next, the process goes to step S306.

In step S306, the thermal probe and the pH probe are combined to form a miniature sensing probe having a hexagonal cylinder. Please cooperate with FIG. 4G. Specifically, the thermal probe and the pH probe can be combined by using an adhesive material. As shown, an adhesive layer 409 is provided between the thermal probe and the PH probe.

In summary, in the manufacturing method of the hexagonal column micro-sensing probe, the base wafer of the thermal probe and the pH probe can be simultaneously formed, and then the heat sensing material and the PH value are respectively formed on the two base wafers. The material is sensed to complete the thermal probe and the pH probe, wherein the heat sensing material and the pH sensing material are not limited to copper coils and yttrium oxide and silver/silver chloride, and then formed by etching with potassium hydroxide The trapezoidal structure, which combines the two to form a miniature sensing probe of a hexagonal cylinder, has the advantage of being easy to process.

Referring to Fig. 5, there is shown a temperature test chart of the hexagonal column micro-sensing probe of the present invention. This measurement uses a four-point resistance method to set a constant current through the copper coil and then measure the voltage across the copper coil. As shown, the resistance change is in the temperature range of 25 ° C to 42.5 ° C between the two points. Each interval is 2.5 °C.

Referring to Fig. 6, there is shown a pressure test chart of the hexagonal cylindrical micro-sensing probe of the present invention. As shown, the upper row of squares shows that the probes with back-to-back joints have better stress, significantly better than probes without back-to-back joints, and probes with back-to-back joints exhibit an average 3.8 Nt stress persistence. Sex.

Referring to Fig. 7, there is shown a PH test chart of the hexagonal cylindrical micro-sensing probe of the present invention. The figure shows the detection result of the pH value of the cerium oxide sensor relative to the silver chloride. As shown in the figure, the potential difference between the cerium oxide and the silver chloride has a linear relationship with the change of the pH value, that is, the hexagonal cylinder of the present invention. The miniature sensing probe provides good pH detection.

In summary, the hexagonal cylindrical micro-sensing probe of the present invention is formed by laminating a metal-based resistive temperature sensing probe and a cerium oxide/silveric acid base alkali sensing probe. Simultaneous sensing of temperature and pH value, not only has good biocompatibility, and its hexagonal cylinder structure can enhance its penetration and maximum crimping force, and will penetrate the object to be tested more easily. Furthermore, the hexagonal micro-sensing probe process is CMOS compatible, making it easy to integrate with existing CMOS chips. Therefore, the hexagonal column micro-sensing probe of the present invention provides instant and accurate sensing, and the process is simple, which will greatly contribute to the development of the micro-sensing probe.

The above-described embodiments are merely illustrative of the principles of the invention and its effects, and are not intended to limit the invention. Modifications and variations of the above-described embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be as set forth in the scope of the claims described below.

1‧‧‧Hexagon cylinder miniature sensing probe

11‧‧‧Hot probe assembly

111‧‧‧ copper coil

112‧‧‧Upper sensing area

113‧‧‧Down sensing area

12‧‧‧PH value probe assembly

121‧‧‧Oxide

122‧‧‧Silver/silver chloride

Claims (11)

A hexagonal cylindrical miniature sensing probe comprises: a thermal probe assembly having a trapezoidal cross section, and a short sensing edge of the thermal probe assembly having two sensing regions formed by a heat sensing material, wherein a sense The measuring area is for sensing the temperature of the object to be tested, the other sensing area is for sensing the ambient temperature; and the PH value probe component having a trapezoidal cross section is formed on the short bottom edge of the PH probe component There are two sensing film regions formed by the pH sensing material, wherein the thermal probe assembly and the PH probe assembly are made of a germanium wafer, and the thermal probe assembly and the pH probe assembly are passed Potassium hydroxide is etched to form a trapezoidal cross-section, and the long bottom edge of the thermal probe assembly is bonded to the long bottom edge of the PH probe assembly to enable the hexagonal micro-sense probe The cross section has a hexagonal column shape. The hexagonal cylindrical micro-sensing probe of claim 1, wherein the thermal sensing material comprises copper or platinum formed by electroplating or polycrystalline germanium formed by electroless plating. The hexagonal column micro-sensing probe according to claim 1, wherein the pH sensing material is silver/silver chloride and yttrium oxide, or is composed of an ion-sensing field-effect transistor. . The hexagonal cylinder micro-sensing probe according to claim 3, wherein the cerium oxide is a sensing electrode for sensing a pH value, and the silver/silver chloride is used for sensing a pH value. Reference electrode. A method of manufacturing a hexagonal cylinder miniature sensing probe, comprising the following Step: forming two sensing regions composed of a thermal sensing material on a first probe base wafer, and etching a portion of the substrate of the first probe base wafer with potassium hydroxide to form a thermal probe, and Forming two sensing film regions formed by the pH sensing material on a second probe base wafer, and etching a portion of the substrate of the second probe base wafer with potassium hydroxide to form a pH probe; The thermal probe and the pH probe are combined using an adhesive material to form a miniature sensing probe having a hexagonal cylinder. The method for manufacturing a hexagonal pillar micro-sensing probe according to claim 5, wherein the processing of the first and second probe base wafers comprises: forming an oxidation by chemical vapor deposition on a substrate And a deposited layer of nitride; defining a probe pattern on the deposited layer, etching the patterned deposited layer by reactive ion etching; and coating the photoresist on the deposited layer to complete etching A conductive pad and a conductive line are formed, and a copper layer and a nickel/gold layer are formed on the deposited layer to form the first and second probe base wafers. A method of fabricating a hexagonal pillar micro-sensing probe according to claim 6 wherein the defining the probe pattern on the deposited layer further comprises coating a photoresist material to define the probe pattern. The method for manufacturing a hexagonal cylindrical micro-sensing probe according to claim 6, wherein before the copper layer is formed on the deposited layer, A layer of titanium/copper is sputtered onto the deposited layer to serve as a seed layer from the titanium/copper layer. The method of manufacturing a hexagonal column micro-sensing probe according to claim 6, wherein the copper layer is formed by electroplating, and the nickel/gold layer is formed by electroless plating. The method for manufacturing a hexagonal cylinder micro-sensing probe according to claim 6, wherein the pH sensing material is silver/silver chloride and cerium oxide, and the silver/silver chloride and the oxidation A silver/silver chloride layer and a ruthenium oxide layer are formed on the nickel/gold layer. The method of manufacturing a hexagonal cylinder micro-sensing probe according to claim 10, wherein the silver/silver chloride layer is coated with a photoresist material to define a silver chloride pad and the silver chloride. The pad is formed by sputtering silver, and the ruthenium oxide layer is formed by electroplating.