TWI601850B - Magnesium oxide thin film hydrogen sensor - Google Patents

Description

Magnesium oxide zinc film hydrogen sensor

The invention relates to a magnesium oxide zinc film hydrogen sensor, in particular, the ruthenium substrate is fixed and placed in a vacuum chamber after being cleaned; the magnesium zinc oxide (MgZnO) film is deposited by radio frequency (RF) magnetron sputtering. Sputtering a target on the germanium substrate, the first sputtering target is a magnesium oxide (MgO) target and a zinc oxide (ZnO) target, and the sputtering gas is argon (Ar); a platinum (Pt) electrode Depositing a second sputtering target on the magnesium zinc oxide (MgZnO) film by radio frequency (RF) magnetron sputtering, the second sputtering target is a platinum (Pt) target, and the sputtering gas is argon (Ar) Thus, when sensing hydrogen (H ₂ ), the temperature is 300 ° C, the hydrogen (H ₂ ) concentration is 1000 ppm, the deposition time is 40 minutes, and the magnesium zinc oxide (MgZnO) film thickness is 423 nm, which has the best sensing sensitivity.

According to the current metal oxide semiconductor (MOS) gas sensors, commonly used in living and industrial environments to detect dangerous gases, generally divided into resistive and capacitive gas sensors, resistive sensing The oxide film is mainly used as a sensing layer. When the gas molecules are contacted, the sensing layer is temporarily combined with the ionized molecules in the gas, so that the resistance value of the oxide film having the metal electrode can be changed, and the sensing is performed. In terms of sensitivity, the oxide is used to adsorb the gas to change its resistance value. Therefore, if the reaction surface area can be increased, the sensitivity and response rate can be greatly improved, and the capacitive sensing gas sensing principle is adopted. Similar to the principle of resistive sensing, the difference is that the sensing layer changes its dielectric constant and then changes the capacitance after adsorbing gas molecules; and hydrogen is a colorless, odorless, odorless, non-toxic flammable under normal temperature and pressure. Sexual gas, it is not easy to detect its existence, but because of its low flash point, it is very easy to burn, and the burning flame is hard to see, burning will Oxygen produces a strong chemical action, which may cause an explosion, so hydrogen sensors are indispensable. Solid electrolyte gas sensors, electrochemical gas sensors, catalytic combustion gas sensors, etc. are common, but not yet. See the sensing of hydrogen (H ₂ ) gas by a magnesium oxide (MgZnO) thin film hydrogen sensor, and how to have the best sensing sensitivity. Therefore, the inventors have the above-mentioned The lack of it is the result of intensive research and improvement, and the invention can be first invented.

The primary object of the present invention is to provide a magnesium oxide zinc thin film hydrogen sensor that provides optimum sensing sensitivity when sensing hydrogen (H ₂ ).

The main feature of the present invention is that the germanium substrate is fixed and placed in the vacuum chamber after being cleaned; the magnesium zinc oxide (MgZnO) film is deposited on the crucible by radio frequency (RF) magnetron sputtering. a substrate, wherein the first sputtering target is a magnesium oxide (MgO) target and a zinc oxide (ZnO) target, the sputtering gas is argon (Ar); and the platinum (Pt) electrode is a radio frequency (RF) Magnetron sputtering depositing a second sputtering target on the magnesium zinc oxide (MgZnO) film, wherein the second sputtering target is a platinum (Pt) target, and the sputtering gas is argon (Ar); When sensing hydrogen (H ₂ ), the temperature is heated to a temperature of 300 ° C at a normal temperature (RT) of 25 ° C, and hydrogen (H ₂ ) is diluted with nitrogen (N ₂ ) to control different concentrations of hydrogen (H ₂ ). It is known that when the power of the sputtered magnesium oxide (MgO) target is fixed at 100 W, the power of the sputtered zinc oxide (ZnO) target is fixed at 125 W, and the deposition time is changed to 40 minutes, and the thickness of the magnesium zinc oxide (MgZnO) film is 423nm, at a temperature of 300 ° C, hydrogen (H ₂ ) concentration of 1000ppm, magnesium oxide (MgO) doping concentration of 1.12wt%, with sensitive sensing ability, the response value is 2.46; another fixed deposition time For 40 minutes, the power of the sputtered zinc oxide (ZnO) target is fixed at 125 W, the power of the sputtered magnesium oxide (MgO) target is controlled to 125 W, and the thickness of the magnesium zinc oxide (MgZnO) film is 423 nm at a temperature of 300 ° C. The hydrogen (H ₂ ) concentration is 1000 ppm, the magnesium oxide (MgO) doping concentration is 1.91% by weight, and has a sensitive sensing capability with a response value of 3.96; therefore, it provides the best sensing sensitivity.

In the magnesium oxide thin film hydrogen sensor of the present invention, the germanium substrate is a P-type germanium substrate having a size of 15 mm x 15 mm, and the germanium substrate is ultrasonically cleaned for 5 minutes.

The magnesium oxide thin film hydrogen gas sensor of the present invention, wherein, when the first sputtering target is deposited on the germanium substrate by radio frequency (RF) magnetron sputtering, the basic pressure of the vacuum chamber is set to be 7×10 ^-5 Torr and the working pressure is 3 mTorr. .

The magnesium oxide thin film hydrogen sensor of the present invention, wherein a radio frequency (RF) magnetron sputtering deposits a second sputtering target on the magnesium zinc oxide (MgZnO) film, and sets a basic pressure of the vacuum chamber 7×10 ^-5 Torr, working pressure 3mTorr.

The magnesium oxide thin film hydrogen gas sensor of the present invention, wherein the platinum (Pt) electrode is a rectangular array having a size of 1 mm x 2 mm, a left-right pitch of 3.5 mm, and a pitch of 1 mm.

The magnesium oxide thin film hydrogen sensor of the present invention, wherein a second sputtering target is deposited on the magnesium zinc oxide (MgZnO) film by radio frequency (RF) magnetron sputtering, and is annealed at a temperature of 400 ° C for 1 hour through a high temperature furnace. .

1‧‧‧Magnesium Oxide Thin Film Hydrogen Sensor

10‧‧‧矽 substrate

11‧‧‧Magnesium zinc oxide (MgZnO) film

12‧‧‧Platinum (Pt) electrode

2‧‧‧Gas testing equipment

20‧‧‧Flow atmosphere chamber

21‧‧‧ bracket

22‧‧‧heater

23‧‧‧Flow Controller (MFC)

24‧‧‧Gas Mixer

25‧‧‧Mechanical Pump (M.P.)

26‧‧‧ Conductive probe

27‧‧‧Platinum line

28‧‧‧Multi-function electric meter

29‧‧‧ computer

The first figure shows a partial cross-sectional view of a combination of embodiments of the present invention.

The second figure shows a combined top view of an embodiment of the invention.

The third figure is a flow chart of an embodiment of the present invention.

The fourth figure is a schematic diagram of gas detection according to an embodiment of the present invention.

The fifth figure shows the response value and film thickness detection reference diagram of the embodiment of the present invention.

The sixth figure is a reference diagram for detecting the response value and the magnesium oxide doping concentration in the embodiment of the present invention.

The seventh figure shows a response value and temperature detection reference diagram of an embodiment of the present invention.

For the purpose of the present invention, the preferred embodiments of the present invention are set forth below, and the following detailed description is given as follows: For the embodiment of the present invention, please refer to the first As shown in the second figure, a magnesium oxide thin film hydrogen sensor 1 is mainly provided, and the magnesium oxide thin film hydrogen sensor 1 is provided with a tantalum substrate 10, a magnesium zinc oxide (MgZnO) thin film 11 and a platinum (Pt) electrode. 12, wherein the crucible substrate 10 is a P-type crucible substrate having a size of 15 mm x 15 mm, and the crucible substrate 10 is ultrasonically cleaned for 5 minutes and then fixed by radio frequency (RF) magnetron sputtering. The vacuum chamber of the device, the radio frequency (RF) magnetron sputtering device can control the flow of the sputtering gas and set the sputtering parameters; the magnesium oxide zinc (MgZnO) film 11 is deposited by radio frequency (RF) magnetron sputtering. A sputtering target is disposed on the germanium substrate 10, wherein the first sputtering target is a magnesium oxide (MgO) target and a zinc oxide (ZnO) target, and the sputtering gas is argon (Ar), and the vacuum chamber is set. a pressure member substantially 7 × 10 ^-5 Torr, working pressure of 3 mTorr; platinum (Pt) electrode 12, system using radio frequency (RF) magnetron sputter deposition of The sputtering target is on the magnesium zinc oxide (MgZnO) film 11, wherein the second sputtering target is a platinum (Pt) target, and the sputtering gas is argon (Ar), and the basic pressure of the vacuum chamber is set to 7×. The platinum (Pt) electrode 12 is a rectangular array having a size of 10 ^-5 Torr and a working pressure of 3 mTorr. The platinum (Pt) electrode 12 has a size of 1 mm x 2 rmm, a left-right pitch of 3.5 mm, and a pitch of 1 mm.

The process of fabrication, setting and sensing of the present invention, as shown in the third figure, is mainly as follows: (a) cleaning the substrate 10: ultrasonic cleaning the substrate 10 for 5 minutes; (b) placing Vacuum chamber: the 矽 substrate 10 is fixed into a vacuum chamber of a radio frequency (RF) magnetron sputtering device; (c) a sputtered magnesium zinc oxide (MgZnO) film 11: a radio frequency (RF) magnetron splash Depositing a first sputtering target on the germanium substrate 10, wherein the first sputtering target is a magnesium oxide (MgO) target (purity: 99.99%) and a zinc oxide (ZnO) target (purity: 99.99%) The sputtering gas is argon (Ar, purity: 99.99%). First, the pre-sputtering time is 5 minutes, that is, the impurities and impurities on the surface of the first sputtering target are removed, and the sputtering parameters are set, that is, the vacuum chamber is set. Body pressure, power, time and gas, for example: basic pressure 7 × 10 ^-5 Torr, working pressure 3mTorr, power 20W ~ 125W, time 10 minutes ~ 80 minutes, gas argon (Ar); (d) splashing platinum ( Pt) electrode 12: depositing a second sputtering target on the magnesium zinc oxide (MgZnO) film 11 by radio frequency (RF) magnetron sputtering, wherein the second sputtering target is platinum (Pt Target (purity: 99.99%), the sputtering gas is argon (Ar, purity: 99.99%), first set the sputtering parameters, that is, set the vacuum chamber pressure, power, time and gas, for example: basic pressure 7 × 10 ^-5 Torr, working pressure 3 mTorr, power 60 W, time 2 minutes, gas argon (Ar); (e) annealing: annealing through a high temperature furnace at a temperature of 400 ° C for 1 hour; (f) hydrogen sensing: using gas As the detection device 2, as shown in the fourth figure, in the detection, the magnesium oxide zinc film hydrogen sensor 1 is first placed in the holder 21 of the flowing atmosphere chamber 20, and the detection parameters are set, and the temperature is controlled by the heater 22. Heating to a temperature of 300 ° C at room temperature (RT) 25 ° C, and introducing nitrogen (N ₂ ) and hydrogen (H ₂ ) via a flow controller (MFC) 23 and a gas mixer (Gas Mixer) 24 to make nitrogen (N _{2 )} Diluting hydrogen (H ₂ ) to control different concentrations of hydrogen (H ₂ ), while mechanical pump (MP) 25 is used for rough pumping, and then with conductive probe 26 at platinum (Pt) electrode 12, Then, the platinum wire 27 is connected to the multi-function electric meter 28, and then the change of the resistance is automatically recorded by the computer 29; therefore, the sensitivity S (Se) is detected. Nsitivity) is defined as the resistance change rate before and after the sensing atmosphere, that is, S=Ro/Rg, the sensitivity S (Sensitivity) is the response value Response (Ro/Rg), and Ro is the zinc oxide film in the air. The resistance value of the hydrogen sensor 1 and Rg is the resistance value of the magnesium oxide thin film hydrogen sensor 1 under hydrogen (H ₂ ).

The invention senses hydrogen (H ₂ ), the temperature is normal temperature (RT) 25 ° C heated to a temperature of 300 ° C, and nitrogen (N ₂ ) dilution of hydrogen (H ₂ ) to control different concentrations of hydrogen (H ₂ ) It can be known that when the power of the sputtered magnesium oxide (MgO) target is fixed at 100W, the power of the sputtered zinc oxide (ZnO) target is fixed at 125W, and the deposition time is changed to 40 minutes, and the magnesium zinc oxide (MgZnO) film is fixed. The thickness is 423nm, the temperature is 300 ° C, the hydrogen (H ₂ ) concentration is 1000ppm, the magnesium oxide (MgO) doping concentration is 1.12wt%, and has a sensitive sensing capability, and the response value is 2.46, as shown in the fifth to seventh figures. The fifth graph is a response value of Response (Ro/Rg) and film thickness (nm) detection. As can be seen from the figure, the thickness of the magnesium zinc oxide (MgZnO) film is 423 nm, and the response value is 2.46. The graph is the response value of Response (Ro/Rg) and Magnesium (MgO) doping concentration (wt%) detection reference chart. It can be seen from the figure that when the doping magnesium oxide (MgO) doping concentration is 1.12wt% The response value is 2.46. The seventh picture is the response value Response (Ro/Rg) and the temperature Temperature (°C) detection reference picture. As can be seen from the figure, the temperature is 300 °C. The response value is 2.46; when the fixed deposition time is 40 minutes, the power of the sputtered zinc oxide (ZnO) target is fixed at 125W, and the power of the sputtered magnesium oxide (MgO) target is controlled to 125W, magnesium zinc oxide (MgZnO). The film thickness is 423 nm, the hydrogen (H ₂ ) concentration is 1000 ppm, the magnesium oxide (MgO) doping concentration is 1.91 wt% at a temperature of 300 ° C, and has a sensitive sensing capability, and the response value is 3.96, as shown in the sixth figure. As can be seen from the figure, when the doping magnesium oxide (MgO) doping concentration is 1.91 wt%, the response value is 3.96, and when the doped magnesium oxide (MgO) doping concentration is 1.12 wt%, the response value is 2.46; The present invention provides optimum sensing sensitivity by varying deposition time, magnesium zinc oxide (MgZnO) film thickness, temperature, hydrogen (H ₂ ) concentration, and magnesium oxide (MgO) doping concentration.

The zinc oxide used in the invention is an N-type semiconductor, the structure is a wurtzite structure, has a high melting point and thermal stability, is soluble in acid and alkali, but is insoluble in water and alcohol, and is a metal oxide semiconductor film, which is At room temperature, with a wide energy gap, greater than the energy of visible light, the zinc oxide film has high transmittance in the visible region, and zinc oxide has higher quantum efficiency and exciton binding energy than other wide-gap semiconductors. At the same time, it has high chemical stability, low electrical constant, high electromechanical coupling coefficient, etc. It can be applied to gas sensors, piezoelectric elements, luminescent materials, solar cells, etc., while undoped zinc oxide film is used. The characteristics are relatively unstable, which is related to the chemical adsorption and desorption ability of oxygen atoms, and is related to the conductivity and preparation method, and the magnesium oxide has a high energy gap. After the magnesium oxide is incorporated into the zinc oxide, the magnesium oxide is modulated. The magnesium content in zinc increases the energy gap of magnesium oxide zinc. When the magnesium content increases, the energy gap increases, the lattice mismatch problem is small, and the crystal structure remains the same as that of zinc oxide. The phase separation occurs, and a magnesium zinc oxide film having a constant lattice structure and a high energy gap is obtained. Therefore, the zinc oxide doped magnesium oxide has the advantages of high thermal stability, good optical characteristics, and energy gap modulation.

In view of the above, the present invention has achieved the intended use and efficacy, and is more desirable and practical than the prior art, but the above embodiments are only specifically described for the preferred embodiment of the present invention. This embodiment is not intended to limit the scope of the patent application of the present invention. The equivalent changes and modifications made by the technical means disclosed in the present invention should be included in the scope of the patent application covered by the present invention.

1‧‧‧Magnesium Oxide Thin Film Hydrogen Sensor

10‧‧‧矽 substrate

11‧‧‧Magnesium zinc oxide (MgZnO) film

12‧‧‧Platinum (Pt) electrode

Claims (6)

A magnesium-magnesium-zinc thin film hydrogen sensor comprises: a germanium substrate which is fixed and placed in a vacuum chamber after being cleaned; a magnesium zinc oxide (MgZnO) film deposited by a radio frequency (RF) magnetron sputtering first sputtering The target is on the germanium substrate, wherein the first sputtering target is a magnesium oxide (MgO) target and a zinc oxide (ZnO) target, and the sputtering gas is argon (Ar); a platinum (Pt) electrode Depositing a second sputtering target on the magnesium zinc oxide (MgZnO) film by radio frequency (RF) magnetron sputtering, wherein the second sputtering target is a platinum (Pt) target, and the sputtering gas is argon ( Ar); Thus, when sensing hydrogen (H ₂ ), the temperature is raised to a temperature of 300 ° C at a normal temperature (RT) of 25 ° C, and hydrogen (H ₂ ) is diluted with nitrogen (N ₂ ) to control different concentrations of hydrogen ( H ₂ ), it can be known that when the power of the sputtered magnesium oxide (MgO) target is fixed at 100 W, the power of the sputtered zinc oxide (ZnO) target is fixed at 125 W, and the deposition time is changed to 40 minutes, and magnesium zinc oxide ( the MgZnO) film having a thickness of 423nm, at a temperature of 300 ℃, hydrogen (H ₂₎ conc. 1000ppm, magnesium oxide (MgO) doping concentration is 1.12 wt%, with sensitive sensing ability, the response value is 2.46; another fixed deposition time is 40 minutes, the power of sputtering zinc oxide (ZnO) target is fixed 125W, control the power of sputtering magnesium oxide (MgO) target to 125W, magnesium oxide zinc (MgZnO) film thickness is 423nm, temperature 300 ° C, hydrogen (H ₂ ) concentration 1000ppm, magnesium oxide (MgO) doping concentration 1.91 Wt%, with sensitive sensing capability, has a response value of 3.96; therefore, it provides the best sensing sensitivity. The magnesium oxide thin film hydrogen gas sensor according to claim 1, wherein the germanium substrate is a P-type germanium substrate, and the germanium substrate has a size of 15 mm x 15 mm, and the germanium substrate is ultrasonically cleaned. minute. The magnesium oxide thin film hydrogen gas sensor according to claim 1, wherein the radio frequency (RF) magnetron sputtering deposits the first sputtering target on the crucible substrate, and sets a basic pressure of the vacuum chamber 7× 10 ^-5 Torr, working pressure 3mTorr. The magnesium oxide thin film hydrogen gas sensor according to claim 1, wherein the radio frequency (RF) magnetron sputtering deposits the second sputtering target on the magnesium zinc oxide (MgZnO) film, and sets the vacuum chamber. The basic pressure of the body is 7 × 10 ^-5 Torr and the working pressure is 3 mTorr. The magnesium oxide thin film hydrogen sensor according to claim 1, wherein the platinum (Pt) electrode is a rectangular array, and the platinum (Pt) electrode has a size of 1 mm x 2 mm and a left-right spacing of 3.5 mm. The upper and lower spacing is 1 mm. The magnesium oxide thin film hydrogen gas sensor according to claim 1, wherein the radio frequency (RF) magnetron sputtering deposits the second sputtering target on the magnesium zinc oxide (MgZnO) film and passes through the high temperature. The furnace was annealed at a temperature of 400 ° C for 1 hour.