Physical vapor deposition preparation method of vanadium oxide film

Abstract

The invention provides a physical vapor deposition preparation method of a vanadium oxide film, which comprises the following steps: S1, pre-sputtering: selecting a target material, adjusting the distance between the target material and a wafer, setting the temperature of a substrate as a preset temperature, setting the vacuum degree of a cavity as a preset vacuum degree, and pre-sputtering the target material under a preset power; s2, sputtering a thin film semi-finished product: transmitting the wafer into a magnetron sputtering vacuum cavity, introducing argon and oxygen into the magnetron sputtering vacuum cavity, setting the reaction pressure of the cavity and the input power of a target material, and sputtering to obtain the sputtered thin film semi-finished product; and S3, sputtering post-treatment is conducted, electron beams are sprayed into the magnetron sputtering cavity through the electron gun, argon and oxygen continue to be introduced into the magnetron sputtering cavity, the cavity reaction pressure and the target input power are set, and a sputtering film is obtained. The vanadium oxide film prepared by the embodiment of the invention is high in surface flatness, and the average resistance temperature coefficient at 22-30 DEG C is up to-2.652% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetron sputtering, and in particular relates to a physical vapor deposition preparation method for a vanadium oxide film. Background Art

[0002] Vanadium oxide films have the advantages of large temperature coefficient of resistance, good resistance performance, low 1 / f noise and compatibility with silicon-based micromachining processes, and are widely used in thermal sensing layers of uncooled infrared imaging systems. The V2O5 phase has good TCR characteristics, but exhibits a large resistivity, while the VO2 phase exhibits a significant phase change effect around 341K, which needs to be avoided in the thermal sensing layer of uncooled infrared imaging systems. Therefore, V2O5 films with less VO2 second phase can show good TCR values ​​and suitable resistance for infrared sensor applications.

[0003] Uncooled microbolometers based on vanadium oxide thin films offer high performance, but the deposition and processing conditions are very stringent, often requiring medium to high temperature deposition and annealing processes. Compatibility with existing complementary metal oxide semiconductor (CMOS) technology is essential for any thermal measurement layer to be used as an infrared sensitive element in microbolometers and infrared imagers. The sensor must be mounted directly on the silicon wafer so that signal processing can be performed efficiently in the infrared focal plane. Therefore, in order to make the microbolometer thermal sensing layer compatible with CMOS technology, the processing temperature during the vanadium oxide preparation process is always kept as low as possible.

[0004] In the prior art, in the reactive magnetron sputtering method, the Chinese patent "A method for preparing a vanadium oxide film with a high resistance temperature coefficient CN201510030113.0" discloses a method for preparing a vanadium oxide film with a high resistance temperature coefficient, in which a silicon nitride film is sputtered on the surface of a single crystal silicon, and a vanadium oxide film, a zinc sulfide film, and a vanadium oxide film are deposited in sequence, and the deposited film samples are annealed. This method requires high-temperature annealing, has poor compatibility with existing complementary metal oxide semiconductor (CMOS) technology, has many film process steps, and has low efficiency. Summary of the invention

[0005] In order to solve at least one technical problem in the prior art, a physical vapor deposition method for preparing a vanadium oxide thin film is provided, which is simple to operate and improves the performance of the metal film. To achieve the above technical objectives, the technical solution adopted in the embodiment of the present invention is: The embodiment of the present invention provides a method for preparing a vanadium oxide thin film by physical vapor deposition, comprising the following steps: Step S1, pre-sputtering: selecting a target material, adjusting the distance between the target material and the wafer, setting the substrate temperature to a preset temperature, the chamber vacuum to a preset vacuum, and pre-sputtering the target material at a preset power; Step S2, sputtering a thin film semi-finished product: introducing argon and oxygen into a magnetron sputtering chamber, setting the chamber reaction pressure and the input power of the target material, and obtaining a sputtered thin film semi-finished product after sputtering; Step S3, post-sputtering treatment: spraying an electron beam into the magnetron sputtering cavity through an electron gun, while continuing to introduce argon and oxygen into the magnetron sputtering cavity, setting the cavity reaction pressure and the input power of the target material, and obtaining a sputtered film; The flow rate of oxygen in step S3 is greater than the flow rate of oxygen in step S2.

[0006] Further, in step S2, the flow rate of oxygen is 1.0 to 5 sccm; And / or, in step S3, the flow rate of oxygen is 10 to 50 sccm.

[0007] Furthermore, in step S3, the voltage of the electron gun is 0.5-1.5 KV, and the current is 5-15 A.

[0008] Furthermore, the input power of the target material in step S2 is greater than the input power of the target material in step S3.

[0009] Further, in step S2, the input power of the target material is 1000-3000W; And / or, in step S3, the input power of the target material is 50-500W.

[0010] In step S1, the target material includes metal vanadium; and / or, the target material has a diameter of 320 to 321 mm, And / or, the wafer is selected from at least one of silicon, gallium arsenide, silicon carbide, quartz glass, aluminum oxide, indium phosphide, gallium nitride, gallium oxide, and aluminum nitride; And / or, the distance between the target and the wafer is 50-150 mm.

[0011] Further, in step S1, the preset temperature is 25-200°C; And / or, the preset vacuum degree is 5.0×10 -8 Torr or less; And / or, the preset power is 1000-3000W; And / or, the pre-sputtering time is 1 to 5 minutes.

[0012] Further, in step S2, the flow rate of argon gas is 15 to 30 sccm; And / or, the reaction pressure of the chamber is 1.0-2.1 mTorr.

[0013] Further, in step S3, the flow rate of argon gas is 1 to 10 sccm; And / or, the reaction pressure of the chamber is 1.0-3.6 mTorr.

[0014] The technical solution provided by the embodiment of the present invention has the following beneficial effects: The embodiment of the present invention increases the plasma density by adding an electron emission device, collides with oxygen molecules, and excites a large number of oxygen anions. The oxygen anions are accelerated into the plasma by the target sheath electric field. Although they may lose electrons in the plasma, their kinetic energy still causes them to be ejected toward the substrate. This bombardment effect will produce a certain etching effect, and the atomic arrangement of the film tends to be flat. The oxygen reaching the surface of the film can repair defects and change the distribution of film components. The vanadium oxide film prepared by the embodiment of the present invention has a high surface flatness, and the average temperature coefficient of resistance at 22 to 30°C is as high as -2.652% or more. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 1 is a SEM image of the cross section and surface of the vanadium oxide film in Example 1 of the present invention.

[0016] Figure 2 1 is an AFM image of the cross section and surface of the vanadium oxide film in Example 1 of the present invention.

[0017] Figure 3 This is the XRD diagram of the vanadium oxide film in Example 1 of the present invention.

[0018] Figure 4 This is the full XPS spectrum of the vanadium oxide film in Example 1 of the present invention.

[0019] Figure 5 This is the XPS fine spectrum of the vanadium (V) element in the vanadium oxide film in Example 1 of the present invention.

[0020] Figure 6 This is a film thickness distribution diagram of the vanadium oxide film in Example 1 of the present invention.

[0021] Figure 7 This is a resistance-temperature variation curve of the vanadium oxide film in Example 1 of the present invention.

[0022] Figure 8 This is a resistance-temperature variation curve of the vanadium oxide film in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] In addition, it should be understood that after reading the contents disclosed in the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the protection scope defined by the present invention.

[0025] The embodiment of the present invention provides a method for preparing a vanadium oxide thin film by physical vapor deposition, comprising the following steps: Step S1, pre-sputtering: selecting a target material, adjusting the distance between the target material and the wafer, setting the substrate temperature to a preset temperature, the chamber vacuum to a preset vacuum, and pre-sputtering the target material at a preset power; Step S2, sputtering a thin film semi-finished product: introducing argon and oxygen into a magnetron sputtering chamber, setting the chamber reaction pressure and the input power of the target material, and obtaining a sputtered thin film semi-finished product after sputtering; Step S3, post-sputtering treatment, spraying an electron beam into the magnetron sputtering cavity through an electron gun, while continuing to introduce argon and oxygen into the magnetron sputtering cavity, setting the cavity reaction pressure and the input power of the target material, and obtaining a sputtered film; The flow rate of oxygen in step S3 is greater than the flow rate of oxygen in step S2.

[0026] It should be noted that, by adding step S3, the sputtered thin film semi-finished product is post-processed. Specifically, an electron beam is added to the sputtering device to enhance the plasma density during sputtering. At the same time, the oxygen flow rate is increased. The electron beam excites a large number of oxygen anions. The oxygen anions are acted upon by the cathode target and move toward the substrate. They interact with the sputtered thin film semi-finished product, causing the atomic arrangement of the sputtered thin film semi-finished product to become flat. The oxygen anions can repair defects and change the component distribution of the sputtered thin film semi-finished product, thereby improving the performance of the sputtered thin film.

[0027] Further, in step S2, the flow rate of oxygen is 1.0 to 5 sccm, for example, 1.0 sccm, 2.0 sccm, 3.0 sccm, 4.0 sccm, 5.0 sccm, etc.; And / or, in step S3, the flow rate of oxygen gas is 10 to 50 sccm, for example, 10 sccm, 20 sccm, 30 sccm, 40 sccm, 50 sccm, etc.

[0028] Further, in step S3, the voltage of the electron gun is 0.5-1.5 KV, and the current is 5-15 A. For example, the voltage may be 0.5 KV, 0.8 KV, 1.0 KV, 1.2 KV, 1.5 KV, etc., and the current may be 5 A, 7 A, 9 A, 10 A, 12 A, 15 A, etc.

[0029] Furthermore, the input power of the target material in step S2 is greater than the input power of the target material in step S3.

[0030] Furthermore, in step S2, the input power of the target material is 1000-3000W, for example, 1000W, 1500W, 2000W, 2500W, 3000W, etc.

[0031] And / or, in step S3, the input power of the target material is 50-500 W, for example, 50 W, 100 W, 200 W, 300 W, 400 W, 500 W, etc.

[0032] In step S1, the target material includes metal vanadium; and / or, the target material has a diameter of 320 to 321 mm, And / or, the wafer is selected from at least one of silicon, gallium arsenide, silicon carbide, quartz glass, aluminum oxide, indium phosphide, gallium nitride, gallium oxide, and aluminum nitride; And / or, the distance between the target and the wafer is 50-150 mm, for example, 50 mm, 80 mm, 100 mm, 120 mm, 150 mm, etc.

[0033] Further, in step S1, the preset temperature is 25-200°C, for example, it can be 25°C, 50°C, 80°C, 100°C, 120°C, 150°C, 180°C, 200°C, etc.

[0034] And / or, the preset vacuum degree is 5.0×10 -8 Torr or less, for example, 1.0×10 -8 Torr, 2.0×10 -8 Torr, 3.0×10 -8 Torr, 4.0×10 -8 Torr et al.

[0035] And / or, the preset power is 1000-3000W, for example, 1000W, 1500W, 2000W, 2500W, 3000W, etc.

[0036] And / or, the pre-sputtering time is 1 to 5 minutes.

[0037] Further, in step S2, the flow rate of argon gas is 15 to 30 sccm, for example, 15 sccm, 18 sccm, 20 sccm, 22 sccm, 25 sccm, 28 sccm, 30 sccm, etc.; And / or, the reaction pressure of the chamber is 1.0-2.1 mTorr, for example, 1.0 mTorr, 1.2 mTorr, 1.5 mTorr, 1.8 mTorr, 2.0 mTorr, 2.1 mTorr, etc.

[0038] Further, in step S3, the flow rate of argon gas is 1 to 10 sccm, for example, 1 sccm, 3 sccm, 5 sccm, 7 sccm, 9 sccm, 10 sccm, etc.; And / or, the reaction pressure of the chamber is 1.0-3.6 mTorr, for example, 1.0 mTorr, 1.5 mTorr, 2.0 mTorr, 2.5 mTorr, 3.0 mTorr, 3.6 mTorr, etc.

[0039] In the following specific examples, the operations involved, if the conditions are not specified, are all carried out under conventional conditions or the conditions recommended by the manufacturer. All raw materials, if the manufacturers and specifications are not specified, are conventional products that can be obtained through commercial purchase.

[0040] Example 1 A method for preparing a vanadium oxide thin film by physical vapor deposition comprises the following steps: Step S1, pretreatment: select a metal vanadium target with a target diameter of 320 mm, set the distance between the target and the wafer stage to 90 mm, set the substrate temperature to 150 °C, and maintain the vacuum degree of the chamber at 4.0×10 -8 Torr, set the sputtering power to 3000W, and pre-sputter the target for 1min; Step S2, sputtering a thin film semi-finished product: introducing argon gas with a flow rate of 15 sccm and oxygen gas with a flow rate of 1.5 sccm into a magnetron sputtering vacuum chamber, setting the reaction pressure of the chamber to 1.1 mTorr and the input power of the target material to 1500 W, and after sputtering for 3 minutes, obtaining a vanadium oxide thin film semi-finished product; Step S3, post-sputtering treatment: an electron beam is sprayed into the magnetron sputtering chamber through an electron gun, the voltage of the electron gun is 1 KV, and the current is 10 A. At the same time, argon gas with a flow rate of 5 sccm and oxygen gas with a flow rate of 15 sccm are continued to be introduced into the magnetron sputtering chamber. The chamber reaction pressure is set to 1.2 mTorr and the input power is 100 W. After sputtering for 3 minutes, a vanadium oxide film is obtained.

[0041] Example 2 A method for preparing a vanadium oxide thin film by physical vapor deposition comprises the following steps: Step S1, pretreatment: select a metal vanadium target with a target diameter of 320 mm, set the distance between the target and the wafer stage to 50 mm, set the substrate temperature to 25 °C, and maintain the vacuum degree of the chamber at 3.0×10 -8 Torr, set the sputtering power to 1000W, and pre-sputter the target for 1min; Step S2, sputtering a thin film semi-finished product: introducing argon gas with a flow rate of 15 sccm and oxygen gas with a flow rate of 1.0 sccm into a magnetron sputtering vacuum chamber, setting the reaction pressure of the chamber to 1.0 mTorr and the input power of the target material to 1000 W, and after sputtering for 3 minutes, obtaining a vanadium oxide thin film semi-finished product; Step S3, post-sputtering treatment: an electron beam is sprayed into the magnetron sputtering chamber through an electron gun, the voltage of the electron gun is 0.5 KV, and the current is 5 A. At the same time, argon gas with a flow rate of 1 sccm and oxygen gas with a flow rate of 10 sccm are continued to be introduced into the magnetron sputtering chamber. The chamber reaction pressure is set to 1.0 mTorr and the input power is 50 W. After sputtering for 3 minutes, a vanadium oxide film is obtained.

[0042] Example 3 A method for preparing a vanadium oxide thin film by physical vapor deposition comprises the following steps: Step S1, pretreatment: select a metal vanadium target with a target diameter of 320 mm, set the distance between the target and the wafer stage to 150 mm, set the substrate temperature to 200 °C, and maintain the vacuum degree of the chamber at 2.0×10 -8 Torr, set the sputtering power to 3000W, and pre-sputter the target for 1min; Step S2, sputtering a thin film semi-finished product: introducing argon gas with a flow rate of 30 sccm and oxygen gas with a flow rate of 5 sccm into a magnetron sputtering vacuum chamber, setting the reaction pressure of the chamber to 2.1 mTorr and the input power of the target material to 3000 W, and after sputtering for 3 minutes, obtaining a vanadium oxide thin film semi-finished product; Step S3, post-sputtering treatment: an electron beam is sprayed into the magnetron sputtering chamber through an electron gun, the voltage of the electron gun is 1.5 KV, and the current is 15 A. At the same time, argon gas with a flow rate of 10 sccm and oxygen gas with a flow rate of 50 sccm are continued to be introduced into the magnetron sputtering chamber. The chamber reaction pressure is set to 3.6 mTorr and the input power is 500 W. After sputtering for 3 minutes, a vanadium oxide film is obtained.

[0043] Comparative Example 1 A method for preparing a vanadium oxide thin film by physical vapor deposition comprises the following steps: Step S1, pre-sputtering: select a metal vanadium target with a target diameter of 320 mm, a distance between the target and the wafer stage of 90 mm, set the substrate temperature to 150 °C, and maintain the chamber vacuum at 4.0 × 10 -8 Torr, set the sputtering power to 3000W, and pre-sputter the target for 1min; Step S2, sputtering thin film: the wafer is transferred to a DC magnetron sputtering vacuum chamber, argon gas with a flow rate of 15 sccm and oxygen gas with a flow rate of 1.5 sccm are introduced, the chamber reaction pressure is set to 1.1 mTorr, the target input power is set to 1500 W, and after sputtering for 3 minutes, a vanadium oxide thin film is obtained.

[0044] Application Examples This application example tests the surface morphology, roughness, crystallinity, film thickness uniformity, stress, and element distribution ratio of the vanadium oxide film prepared in Example 1, and tests the electronic temperature coefficient (TCR) performance of the vanadium oxide film prepared in Example 1 and Comparative Example 1. Specifically, the surface morphology and roughness of the vanadium oxide film are observed by scanning electron microscopy (SEM), and the SEM test instrument is Hitachi S-4800; the roughness of the surface of the vanadium oxide film is tested by atomic force microscopy (AFM), and the AFM test instrument is BrukerDimension® Icon™; the crystallinity of the vanadium oxide film is tested by X-ray diffraction (XRD), and the XRD test instrument is Brukersmart apex Ⅱ; the element distribution ratio of vanadium oxide is calculated by X-ray photoelectron spectroscopy (XPS), and the XPS test instrument is Thermo Scientific K-Alpha; the temperature coefficient of resistance (TCR) of the vanadium oxide film is measured by a four-probe measurement method, and the TCR test instrument is Changzhou Xinyang CXT2665 four-probe square resistance tester.

[0045] The XPS fine spectrum results of the vanadium (V) element of the vanadium oxide film in Example 1 are shown in Table 1 below, and the XPS full spectrum results of the vanadium oxide film are shown in Table 2 below: Table 1 is the XPS fine spectrum results of vanadium (V) element in the vanadium oxide film in Example 1 of the present invention

[0046] Table 2 is the XPS full spectrum results of the vanadium oxide film in Example 1 of the present invention:

[0047] Depend on Figure 1 , Figure 2 As shown in Table 1, the surface roughness of the vanadium oxide film prepared in Example 1 of the present invention is relatively small and the surface is flat, with a roughness Ra of only 0.463 nm.

[0048] Depend on Figure 3 It can be seen that the XRD spectrum of the substrate is similar to that of the vanadium oxide thin film SiO2 / VO prepared in Example 1 of the present invention. x The peaks of the spectra are almost the same. No VO was found in the comparison between the two. xThe characteristic peak of Si is only observed at 2θ≈33°, and the peak position of 50-60° is the characteristic peak of SiO2. The results show that the VO deposited in Example 1 of the present invention x The film is amorphous.

[0049] Depend on Figure 4 As can be seen from Table 1, the vanadium oxide film prepared in Example 1 of the present invention mainly has four peaks, namely O1s, V2p, C1s and N1s. Among them, the O2s peak and the V2p peak are relatively close and require fine spectral analysis. The C1s peak and the N1s peak indicate surface C and N, which are both caused by inevitable surface contamination during the film characterization test.

[0050] Depend on Figure 5 As shown in Table 2, the peak position of the V (2p3 / 2) electron layer of the vanadium oxide film prepared in Example 1 of the present invention is 517.38 eV, and the range is 516.8 eV to 517.7 eV, which is mainly V 5+ (The element ratio is 62.53%), there is a small peak at 516.04 eV, ranging from 515.64 eV to 516.04 eV, mainly V 4+ (The element ratio is 37.47%).

[0051] Depend on Figure 6 It can be seen that the thickness of the vanadium oxide film prepared in Example 1 is 534Å, and the film thickness uniformity is 0.899%. x The film stress is about 120.7MPz.

[0052] Figure 7 It can be seen from the linear fitting TCR that the average resistance temperature coefficient of the vanadium oxide film prepared in Example 1 at 22-30°C is as high as -2.652%. Figure 8 It can be seen that the average resistance temperature coefficient of the vanadium oxide film prepared in Comparative Example 1 is above -2.487% at 22-30°C. It can be seen that the average resistance temperature coefficient performance of the vanadium oxide film can be effectively improved through the sputtering post-treatment in step S3.

[0053] In summary, the vanadium oxide film prepared in Example 1 of the present invention has high surface flatness, and the average temperature coefficient of resistance at 22-30° C. is as high as -2.652% or more, which meets the use requirements.

[0054] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a vanadium oxide thin film by physical vapor deposition, characterized in that: The following steps are involved: Step S1, pre-sputtering: selecting a target material, adjusting the distance between the target material and the wafer, setting the substrate temperature to a preset temperature, the chamber vacuum to a preset vacuum, and pre-sputtering the target material at a preset power; Step S2, sputtering a thin film semi-finished product: introducing argon and oxygen into a magnetron sputtering chamber, setting the chamber reaction pressure and the input power of the target material, and obtaining a sputtered thin film semi-finished product after sputtering; Step S3, post-sputtering treatment: spraying an electron beam into the magnetron sputtering cavity through an electron gun, while continuing to introduce argon and oxygen into the magnetron sputtering cavity, setting the cavity reaction pressure and the input power of the target material, and obtaining a sputtered film; The flow rate of oxygen in step S3 is greater than the flow rate of oxygen in step S2.

2. The method for preparing a vanadium oxide thin film by physical vapor deposition according to claim 1, characterized in that: In step S2, the flow rate of oxygen is 1.0 to 5 sccm; And / or, in step S3, the flow rate of oxygen is 10 to 50 sccm.

3. The method for preparing a vanadium oxide thin film by physical vapor deposition according to claim 1, characterized in that: In step S3, the voltage of the electron gun is 0.5-1.5KV, and the current is 5-15A.

4. The method for preparing a vanadium oxide thin film by physical vapor deposition according to claim 1, characterized in that: The input power of the target material in step S2 is greater than the input power of the target material in step S3.

5. The method for preparing a vanadium oxide thin film by physical vapor deposition according to claim 1, characterized in that: In step S2, the input power of the target is 1000-3000W; And / or, in step S3, the input power of the target material is 50-500W.

6. The method for preparing a vanadium oxide thin film by physical vapor deposition according to claim 1, characterized in that: In step S1, the target material includes metal vanadium; and / or, the target material has a diameter of 320 to 321 mm, And / or, the wafer is selected from at least one of silicon, gallium arsenide, silicon carbide, quartz glass, aluminum oxide, indium phosphide, gallium nitride, gallium oxide, and aluminum nitride; And / or, the distance between the target and the wafer is 50-150 mm.

7. The method for preparing a vanadium oxide thin film by physical vapor deposition according to claim 1, characterized in that: In step S1, the preset temperature is 25-200°C; And / or, the preset vacuum degree is 5.0×10 -8 Torr or less; And / or, the preset power is 1000-3000W; And / or, the pre-sputtering time is 1 to 5 minutes.

8. The method for preparing a vanadium oxide thin film by physical vapor deposition according to claim 1, characterized in that: In step S2, the flow rate of argon gas is 15 to 30 sccm; And / or, the reaction pressure of the chamber is 1.0-2.1 mTorr.

9. The method for preparing a vanadium oxide thin film by physical vapor deposition according to claim 1, characterized in that: In step S3, the flow rate of argon gas is 1 to 10 sccm; And / or, the reaction pressure of the chamber is 1.0-3.6 mTorr.

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