CN2585868Y - Appts. for co-evaporating preparing thin film by adopting eddy heating for heating target material - Google Patents

Abstract

The utility model relates to a device for preparing thin films by co-evaporation of target materials heated by eddy currents. The device installs at least one set of eddy current heaters made of target suspension tubes, hollow water-cooled tubes, induction coils, auxiliary induction coils, induction power supplies, and auxiliary induction power supplies in the vacuum coating equipment; the induction coils and auxiliary induction coils are uniformly wound On the upper and lower parts of the outer wall of the target suspension tube, two adjacent turns are kept insulated, and the induction coil is electrically connected to the power supply; the induction power supply is electrically connected to the computer respectively. The utility model realizes that the evaporation material is suspended without being in contact with the container, thereby avoiding the pollution of the film by boat evaporation. The obtained 123-phase _{YBa2Cu3O7 -delta} superconducting film has a thickness of _200-2000nm and a zero-resistance temperature of 89-91K. J _c is 2-4 MA/cm ² . Measurements show that the film is a high-quality superconducting film.

Description

Apparatus for preparing thin films by co-evaporation of eddy current heating targets

The invention relates to a method and a device for preparing a thin film, in particular to a device for preparing a thin film by co-evaporation of a target material heated by eddy currents.

Commonly used methods for preparing thin films are pulsed laser deposition (hereinafter referred to as PLD), sputtering, electron beam co-evaporation and thermal co-evaporation. The PLD method can grow thin films with excellent properties, but its growth rate will slow down with the increase of film area and thickness, and the difficulty of preparation will also increase rapidly. In addition, the PLD method also requires an expensive high-power excimer laser, and the preparation of a thin film by the PLD method will produce small particles, which will affect the quality of the film. As described in Document 1: Double-sided YBa ₂ Cu ₃ O _7-δ thin films made by off-axis pulsed laser deposition, supercond. Sci. Technol. 14, 543-547, 2001. Thin films were prepared by sputtering, such as Document 2: Uniformdeposition of YBa ₂ Cu ₃ O _7-δ thinfilms over an 8 inch diameter area by a 90°off-axis sputtering technique, Appl.Phys.Lett.69(25)3911, Introduced in 1996, this method is prone to reverse sputtering, which reduces the quality of the film. Electron beam co-evaporation to prepare large-area films, as described in Document 3: Properties of thin and ultra-thin YBCO films grown by aCo-evaporation technique, Journal of Alloys and Compounds251, 156-160, 1997: Electron gun for this method, heat source etc. all require ultra-high vacuum, and the growth of some thin films, such as high-temperature superconducting films, requires oxygen, and the electron gun equipment must use high voltage. Therefore, these reasons cause the equipment of this method to be complicated and expensive. In addition, this method generally requires post-annealing treatment, which is not suitable for preparing large-area high-temperature superconducting thick films. Although the thermal co-evaporation method can realize the deposition of large-area films, as document 4: Continuous YBa ₂ Cu ₃ O _7-δ Film Deposition by Optically Controlled Reactivethermal Co-evaporation, IEEE Transactions on Applied Superconductivity, 7, 1181-1184, 1997 As stated in the article, this method has the advantages of simple equipment structure, good uniformity of deposited film, high quality, fast deposition rate, etc. It has been applied to deposit large-area superconducting films of 3-9 inches, and has a wide range of applications. market application prospects. However, this method also has its own defects. For example, metal tungsten and tantalum materials are usually used as heat boats. These two materials are easily oxidized in oxygen and evaporated at high temperatures. Therefore, in the process of film formation, tungsten or tantalum doped Into the film, greatly reducing the quality of the film.

The purpose of the present invention is to overcome the above-mentioned shortcoming that metal material is used as the heat boat, and the heat boat material is easily oxidized during the film forming process, resulting in a decrease in film quality, and provides a device for preparing thin films by co-evaporation of eddy current heating targets.

The purpose of the present invention is achieved like this:

The device for preparing thin films by co-evaporation of eddy current heating targets provided by the present invention includes: a vacuum chamber with a quartz window, an infrared thermometer, and a vacuum unit connected to the vacuum chamber installed on both sides of the vacuum chamber, above the vacuum chamber Install the substrate heater, baffle plate and light barrier; the high-pressure gas cylinder communicates with the vacuum chamber through the needle valve on the wall of the vacuum chamber; the control computer is electrically connected with the control power supply and the substrate heater; it is characterized in that: it also includes at least one set consisting of A target suspension tube installed in the vacuum chamber, an induction coil made of a hollow water-cooled tube and a sub-induction coil, an induction power supply and an eddy current heater made of a sub-induction power supply; the hollow water-cooled tube is connected to the external water cooling system, and the induction coil and the sub-induction The coil is evenly wound on the upper and lower parts of the outer wall of the target suspension tube, and the adjacent two turns are kept insulated. The leads at both ends of the induction coil are respectively connected to the output terminals of the induction power supply and the secondary induction power supply; the induction power supply is electrically connected to the computer; the substrate is heated The device is located in the lower part of the vacuum chamber and is opposite to the target suspension nozzle. The evaporation target material is placed in the target suspension tube, and a baffle and a diaphragm are placed between the substrate and the target suspension nozzle.

The eddy current heater includes 1-6 sets installed in the same vacuum chamber.

The number of turns of the induction coil is 1-100 turns, and the number of turns is related to the required evaporation temperature, the diameter, thickness, and resistivity of the evaporation target, and the output frequency and power of the high-frequency power supply. The floating position of the target can be controlled and stabilized by adjusting the current of the auxiliary induction coil.

The output alternating frequency of the induction power supply and the auxiliary induction power supply may be 50Hz-100MHz.

The induction coil and auxiliary induction coil include: a hollow water-cooled copper tube, a hollow silver tube, or a hollow spiral tube made of other conductive materials.

The target suspension tube includes: made of quartz, ceramics, glass or other insulating materials.

The device of the present invention adopts the hollow water-cooled induction coil to be evenly wound on the outer wall of the target suspension tube according to the calculated number of turns. , Thickness, resistivity and frequency and power of high-frequency power output. In order to maintain a good water cooling effect, in addition, the tube wall must have an appropriate thickness to ensure that high frequency and large current can pass through. This design mainly uses the electromagnetic induction effect and Lenz's law. When the coil is connected to the high-frequency alternating power supply, the high-frequency alternating current excites a strong high-frequency alternating magnetic field in the coil. At this time, the alternating magnetic flux An eddy current is generated inside the passing conductive target, which releases a large amount of Joule heat, reaches the deposition temperature, and realizes the growth of the film. In addition, due to the interaction between the magnetic flux and the eddy current magnetic field, the target is subject to the levitation force, and the target will be suspended when the levitation force is greater than the gravity. The auxiliary induction coil produces a force in the same direction as the gravity, and the position where the force generated by the induction coil and the auxiliary induction coil and the gravity is zero is the stable position of the target.

The advantage of the present invention is that the device can suspend the evaporation material without contact with the container, avoid the pollution of the film by boat evaporation, can be used in an aerated environment, including an oxygen environment, has the advantages of fast deposition rate and easy control, etc. It is suitable for preparing different kinds of thin films by thermal evaporation method. In addition, it heats everywhere inside the metal at the same time, instead of transferring heat from the outside, so the heating efficiency is high and the speed is fast. In addition, the induction coil can be connected to the electrode and the water cooling device at the same time, so as to realize the water cooling of the system while heating the evaporation target, so as to achieve the purpose of simplifying the structure of the equipment.

Description of drawings

Fig. 1 is a schematic diagram of the structure and composition of the co-evaporation device of the present invention.

Fig. 2 is a schematic structural diagram of the eddy current heater in the co-evaporation device of the present invention.

(1) Target suspension tube; (2) Induction coil (hollow water-cooled tube);

(3) Secondary induction coil (hollow water-cooled tube); (4) Induction power supply;

(5) Secondary induction power supply; (6) Vacuum unit;

(7) Control computer; (8) Thermometer;

(9) Inflatable device; (10) Temperature control device;

(11) Substrate heater; (12) Vacuum chamber;

(13) baffle; (14) light bar

Detailed ways

Embodiment 1: the present invention will be further described below in conjunction with accompanying drawing 1, 2 and embodiment:

As shown in Figures 1 and 2, a device for preparing thin films by co-evaporation without contact heating was fabricated. The target suspension tube 1 is made of quartz with a diameter of 10 cm and a height of 35 cm; the induction coil 2 and the auxiliary induction coil 3 are wound with hollow copper water-cooled tubes. The diameter of the hollow copper water-cooled tube used is 30mm, and 10 turns are evenly wound outside the target suspension tube 1 made of quartz sleeve. When winding, pay attention to the appropriate gap, and ensure that the adjacent two turns are kept insulated; the induction coil 2 and the auxiliary induction coil The leads at both ends of 3 are electrically connected to the induction power supply 4 and the auxiliary induction power supply 5 outside the vacuum chamber 12 respectively; the vacuum chamber 12, the baffle plate 13 and the adjustable light bar 14 are made of stainless steel. Above the vacuum chamber 12 is a substrate heater 11, which is connected to a control power supply 10, and the vacuum degree of the vacuum chamber is maintained by the air pumping device 6 and the gas charging device 9 on both sides. The temperature of the substrate is measured by an infrared thermometer 8 through a quartz window. For the part of the eddy current heater, the heater is located in the lower part of the vacuum chamber, and the evaporation target is placed in the target suspension tube 1 . The current and voltage output by the power supply are controlled by the computer 7 respectively. In the vacuum reaction chamber, a baffle 13 and a shutter 14 are also placed between the substrate and the target suspension nozzle to control the evaporation rate. The substrate temperature was measured by a SCIT infrared thermometer by observing the quartz window.

Example 2:

Make a non-contact heating co-evaporation device for thin film preparation as shown in Figure 1, except that three sets of eddy current target heaters (as shown in Figure 2) are arranged in the vacuum chamber 12 for co-evaporation method to prepare YBa ₂ Cu ₃ O _7-δ superconducting thin films. In the three sets of eddy current target heaters, the induction coil 2 and the auxiliary induction coil 3 are respectively connected to their respective alternating induction power supplies; the distance between the heater and the substrate is adjusted, and metal copper, metal yttrium and barium fluoride are respectively placed in three The target is suspended in tube 1.

A three-inch large-area yttrium-barium-copper-oxide (YBa ₂ Cu ₃ O _7-δ ) superconducting thin film was prepared using the device in Example 2.

First, clean the evaporation target metal yttrium, barium fluoride, and metal copper and place them in the target suspension tube, fix the substrate on the substrate heater, close the vacuum chamber and turn on the water cooling system of the device to reduce the system temperature; then turn on The vacuum unit evacuates the system and maintains the pressure of the vacuum reaction chamber at 10 ^-4 Pa to ensure that the target vapor can be evaporated to the surface of the substrate; then the temperature of the substrate is raised to 200-800°C long film temperature, and adjust the high-frequency alternating induction power supply output 30MHz, the output power is 3000W, so that the evaporation target reaches the required evaporation temperature (the evaporation temperature is determined by the melting point of the evaporation target ); Metal copper and metal yttrium targets are respectively used to reach the required temperature for evaporation with their own eddy current heating devices. Barium fluoride is heated to the required temperature by another metal yttrium boat heated by eddy current, and the molar ratio of metal yttrium, barium fluoride, and metal copper evaporation is controlled to be 1:2:3, and the evaporation duration is 5-30 Minutes; turn on the light barrier and the baffle target to start evaporation during evaporation, and the temperature of the target is measured by an infrared thermometer.

Example 3

This embodiment is shown in Figure 1. The target suspension tube 1 is made of aluminum oxide, with a diameter of 5 cm and a height of 35 cm; the induction coil 2 and the secondary induction coil 3 are wound with hollow copper water-cooled tubes. The hollow copper water-cooled tube used has a diameter of 3 or 25mm, and 15 turns are evenly wound outside the aluminum oxide sleeve. When winding, pay attention to the appropriate pores, and keep the two adjacent turns insulated. The device for preparing the buffer layer of the metal substrate by the co-evaporation method has two sets of eddy current target heaters, which are respectively connected to their own alternating power sources; the vacuum chamber 12, the baffle plate 13 and the adjustable light bar 14 are made of stainless steel. Adjust the distance between the heater and the substrate, and place gold magnesium and metal cerium in the two heaters respectively.

Claims (6)

1. A device for preparing thin films by co-evaporation of eddy current heating targets, comprising: a vacuum chamber with a quartz window, and a vacuum unit connected to the vacuum chamber installed on both sides of the vacuum chamber, and a substrate heater is installed above the vacuum chamber , baffle plate and light barrier; the high-pressure gas cylinder communicates with the vacuum chamber through the needle valve on the wall of the vacuum chamber; the control computer is electrically connected with the control power supply and the substrate heater; and has an infrared thermometer; it is characterized in that: it also includes at least A set of eddy current heaters made of a target suspension tube installed in a vacuum chamber, an induction coil made of a hollow water-cooled tube, a secondary induction coil, an induction power supply and a secondary induction power supply; the induction coil and the secondary induction coil are evenly wound on the target suspension tube The upper and lower parts of the outer wall are kept insulated, and the two ends of the induction coil and the auxiliary induction power supply are respectively connected to the induction power supply outside the vacuum chamber and the output end of the auxiliary induction power supply; the induction power supply is electrically connected to the computer; the substrate is heated The device is located in the lower part of the vacuum chamber, the evaporation target is placed in the target suspension tube, and a baffle and a light barrier are placed between the substrate and the target suspension tube. 2. The device for preparing thin films by co-evaporation of eddy current heating targets according to claim 1, characterized in that: said eddy current heaters include 1-6 sets in the same vacuum chamber. 3. The device for preparing thin films by co-evaporation of eddy current heating targets according to claim 1, characterized in that: the number of turns of the induction coil is 1-100 turns. 4. The device for preparing thin films by co-evaporation of eddy current heating targets according to claim 1, characterized in that: the output alternating frequency of the induction power supply and the auxiliary induction power supply is 50 Hz-100 MHz. 5. The device for preparing thin films by co-evaporation of eddy current heating targets according to claim 1, characterized in that: the induction coil and the secondary induction coil include: hollow water-cooled copper tubes, hollow silver tubes, or other conductive Hollow spiral tube made of material. 6. The device for preparing thin films by co-evaporation of eddy current heating targets according to claim 1, characterized in that: said target suspension tubes are made of quartz, ceramics, glass or other insulating materials.

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