Tantalum film preparation method, system, chip and equipment

Abstract

The invention discloses a tantalum film preparation method and system, a chip and equipment, and relates to the technical field of chips. The method comprises the following steps: connecting a tantalum target material and a substrate with two poles of a direct current source; in a vacuum environment at room temperature, the power of the direct current source is adjusted to be within a first power range, so that the first gas generates a glow discharge phenomenon, plasma generated by the first gas due to the glow discharge phenomenon bombards the tantalum target material to sputter tantalum, and the tantalum is deposited on the substrate to generate a pure alpha-phase tantalum film; wherein the temperature range of the room temperature is 20-40 DEG C, and the first gas is a non-reaction gas relative to the sputtered tantalum. According to the embodiment of the invention, the pure alpha-phase tantalum film can be directly generated on the substrate in a room temperature environment, the substrate does not need to be heated to a high temperature (such as more than 400 DEG C), and a seed layer does not need to be prepared on the substrate in advance, so that the preparation efficiency of the pure alpha-phase tantalum film is effectively improved, and the preparation cost of the pure alpha-phase tantalum film is reduced.

Description

Technical Field

[0001] This application relates to the field of chip technology, and in particular to a method, system, chip, and device for preparing tantalum film. Background Technology

[0002] Superconducting quantum chips are fabricated based on superconducting thin films (such as aluminum (Al), niobium (Nb), titanium nitride (TiN), tantalum (Ta), etc.) deposited on substrates such as silicon / sapphire. Currently, superconducting quantum chips typically use pure alpha-phase tantalum films as the bottom film. Pure alpha-phase tantalum films refer to tantalum films whose crystal morphology is entirely alpha-phase (i.e., having a body-centered cubic (BBC) structure).

[0003] In related technologies, a high-temperature, long-film method is used to prepare pure α-phase tantalum films, such as in a high-vacuum environment (e.g., ~10). -9 Torr-level to ~10 -3 In the superconducting quantum chip (TQC) process, the substrate of the superconducting quantum chip is heated to a high temperature (e.g., greater than 400 degrees Celsius) so that the crystal morphology of tantalum is α phase during the deposition of tantalum onto the substrate, thereby obtaining a pure α phase tantalum film.

[0004] However, high-temperature film growth requires gradually heating the substrate from room temperature to a high temperature and maintaining this temperature for a period of time to ensure it reaches a stable high temperature before the pure α-phase tantalum film is formed. Furthermore, after the pure α-phase tantalum film growth is complete, the substrate needs to cool from the high temperature to room temperature. Since the growth of the pure α-phase tantalum film is carried out in a high vacuum environment, the lack of thermally conductive air makes the cooling process very lengthy, taking, for example, 4-8 hours. This results in a long preparation time and low efficiency for the pure α-phase tantalum film. Summary of the Invention

[0005] This application provides a method, system, chip, and apparatus for preparing a tantalum film. The technical solution is as follows:

[0006] According to one aspect of the embodiments of this application, a method for preparing a tantalum film is provided, the method comprising:

[0007] Connect the tantalum target and substrate to the two poles of a DC source;

[0008] In a vacuum environment at room temperature, the power of the DC source is adjusted to a first power range so that the first gas produces a glow discharge phenomenon. The plasma generated by the glow discharge phenomenon bombards the tantalum target to sputter tantalum, and the tantalum is deposited on the substrate to generate a pure α-phase tantalum film.

[0009] The room temperature range is 20 degrees Celsius to 40 degrees Celsius, and the first gas is a non-reactive gas relative to the sputtered tantalum.

[0010] According to one aspect of the embodiments of this application, a tantalum film preparation system is provided, the tantalum film preparation system including a sputtering chamber and a DC source, the sputtering chamber including a substrate base and a target base;

[0011] The target base is used to place the tantalum target.

[0012] The substrate base is used to place the substrate;

[0013] The DC source is used to connect the tantalum target and the substrate; in a vacuum environment at room temperature, the power is adjusted to a first power range so that the first gas generates a glow discharge phenomenon, and the plasma generated by the first gas due to the glow discharge phenomenon bombards the tantalum target to sputter tantalum, and the tantalum is deposited on the substrate to generate a pure α phase tantalum film.

[0014] The room temperature range is 20 degrees Celsius to 40 degrees Celsius, and the first gas is a non-reactive gas relative to the sputtered tantalum.

[0015] According to one aspect of the present application, a chip is provided, wherein the underlying film on the chip is prepared by the tantalum film preparation method described above.

[0016] According to one aspect of the present application, an apparatus is provided, the apparatus including a chip, wherein the underlying film on the chip is prepared by the tantalum film preparation method described above.

[0017] The technical solutions provided in this application embodiment may have the following beneficial effects:

[0018] By adjusting the power of the DC source acting on the substrate and the tantalum target to a first power range, the tantalum sputtered on the tantalum target has suitable energy to be deposited on the substrate to form a pure α-phase tantalum film. This enables the direct formation of a pure α-phase tantalum film on the substrate at room temperature without heating the substrate to a high temperature (e.g., greater than 400 degrees Celsius). Compared with the high-temperature long film method in related technologies, this application can effectively reduce the time required for temperature processing during the preparation process, thereby reducing the preparation time of the pure α-phase tantalum film and thus improving the preparation efficiency of the pure α-phase tantalum film.

[0019] Furthermore, since this application does not require the pre-preparation of a seed layer on the substrate (seed layer growth method), it eliminates the need for additional target materials for seed layer preparation and additional target placement processes. Compared to the seed layer growth method, this application saves on the costs associated with the seed layer, thereby reducing the preparation cost of pure α-phase tantalum films. Simultaneously, it avoids the cross-contamination problem between different target materials caused by the seed layer (because there is no isolation between multiple target materials, when one target material is deposited, the same material may also be deposited on other target materials).

[0020] Furthermore, regarding the photoresist fabrication process, since it eliminates the need to heat the substrate to high temperatures, it avoids a series of negative impacts such as deformation, denaturation, and release of impurity gases that easily occur with photoresist at high temperatures. Therefore, the technical solution provided in this application is compatible with processes involving photoresist. Since the technical solution provided in this application does not require heating the substrate to high temperatures, it is also applicable to superconducting quantum chips containing photoresist-based components such as air bridges and Josephson junctions, thereby improving the versatility and applicability of the technical solution provided in this application. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a tantalum film preparation method provided by related technologies;

[0022] Figure 2 This is a schematic diagram of another tantalum film preparation method provided by related technologies;

[0023] Figure 3 This is a schematic diagram of a tantalum film preparation system provided in one embodiment of this application;

[0024] Figure 4 This is a flowchart of a tantalum film preparation method provided in one embodiment of this application;

[0025] Figure 5 This is a schematic diagram of a tantalum film preparation method provided in one embodiment of this application;

[0026] Figure 6 This is a flowchart of a tantalum film preparation method provided in another embodiment of this application;

[0027] Figure 7 This is a schematic diagram of X-ray diffraction data provided in one embodiment of this application;

[0028] Figure 8 This is a schematic diagram of X-ray diffraction data provided in another embodiment of this application;

[0029] Figure 9 This is a comparative image of a pure α-phase tantalum film provided in one embodiment of this application;

[0030] Figure 10 This is a schematic diagram of the distribution of decoherent data in a superconducting quantum chip provided in one embodiment of this application;

[0031] Figure 11 This is a schematic diagram of a tantalum film preparation system provided in another embodiment of this application. Detailed Implementation

[0032] Before introducing the technical solutions of this application, some terms involved in this application will be explained. The following related explanations are optional solutions and can be arbitrarily combined with the technical solutions of the embodiments of this application, all of which fall within the protection scope of the embodiments of this application. The embodiments of this application include at least some of the following contents.

[0033] A superconducting quantum chip is a chip used for superconducting quantum computing. Superconducting quantum chips can be fabricated based on superconducting thin films (such as aluminum (Al), niobium (Nb), titanium nitride (TiN), or tantalum) deposited on substrates such as silicon (Si) or sapphire Al₂O₃ (aluminum oxide). The first film deposited on the substrate is usually called the bottom film of the superconducting quantum chip. If this film is aluminum, the chip can be called an aluminum-based superconducting quantum chip; if the film is tantalum, the chip can be called a tantalum-based superconducting quantum chip, and so on.

[0034] Superconducting quantum chips are composed of components, such as readout lines, resonant cavities, bit capacitors, control lines, air bridges, Josephson junctions, indium pillar solder joints, and deep holes. These components can also be fabricated from superconducting thin films using processes such as photolithography.

[0035] Superconducting refers to a property of a material that, below a certain temperature, exhibits a sudden change in electrical resistance to zero and complete diamagnetism.

[0036] Airbridge: A component in superconducting quantum chips that has an arch-like structure.

[0037] Josephson Junction: A component in superconducting quantum chips, which has a sandwich-stacked layered structure formed by superconductor-insulator-superconductor.

[0038] The main body of a superconducting quantum chip is a superconducting thin film, also called the bottom film, deposited on a substrate. On this superconducting thin film, components of the superconducting quantum chip, such as readout lines, resonant cavities, bit capacitors, and control lines, can be fabricated using methods such as photolithography and etching. These components determine the decoherence performance of the superconducting quantum chip. Two commonly used substrates in superconducting quantum chips are Si (001) planes and Al2O3 (0001) planes, also called c-plane sapphire, both of which have low microwave losses. Since signals in a superconducting quantum chip are transmitted via microwaves, a substrate with low microwave loss is chosen for depositing the bottom film. The aforementioned (001) and (0001) planes are used to indicate crystal planes. For example, the (0001) plane can be used to indicate hexagonal lattice patterns in a hexagonal crystal system; for instance, Al2O3 (0001) can be used to indicate hexagonal lattice patterns on a sapphire substrate.

[0039] In the field of superconducting quantum computing, it has been verified that tantalum-based superconducting quantum chips generally outperform traditional aluminum-based superconducting quantum chips. Obtaining a pure alpha-phase tantalum film is crucial for high-performance tantalum-based superconducting quantum chips. This pure alpha-phase tantalum film is typically used as the bottom film in tantalum-based superconducting quantum chips, grown on low-microwave-loss substrates such as silicon or sapphire. Through processes such as photolithography and etching, components such as readout lines, resonant cavities, bit capacitors, and control lines can be formed on the pure alpha-phase tantalum film.

[0040] The internal quality factor Q of the resonant cavity i This directly determines the decoherence lifetime of superconducting quantum chips. Numerous experiments in the field of superconducting quantum chips have confirmed that pure α-phase tantalum films can enable resonant cavities to possess a high internal quality factor Q. i Therefore, obtaining a pure α-phase tantalum film is the key to fabricating high-performance superconducting quantum chips.

[0041] Tantalum is a metallic element with atomic number 73 and the chemical symbol Ta. The elemental form of tantalum (a pure substance composed of the same element) is a steel-gray metal. Tantalum has high chemical stability and excellent corrosion resistance, exhibiting strong resistance to concentrated sulfuric acid, hydrochloric acid, and alkalis. Furthermore, tantalum has a high melting point and low vapor pressure, making it suitable for high-temperature environments. It also has good cold-working properties, making it widely applicable in many fields such as chemical engineering, steel, metallurgy, medical, electronics, and nuclear energy. Tantalum also exhibits superconductivity at low temperatures, with a superconducting transition temperature of 4.4 K.

[0042] Tantalum typically exists in two phases: an α phase with a body-centered cubic (BCC) structure and a β phase with a tetragonal structure. The key to achieving long decoherence times in tantalum-based superconducting quantum chips lies in growing a pure α-phase tantalum film. Due to the high evaporation temperature of tantalum, magnetron sputtering equipment is generally used to grow the tantalum film. Magnetron sputtering equipment can refer to any equipment based on magnetron sputtering technology.

[0043] Pure α-phase tantalum film: A tantalum film in a crystalline form with a body-centered cubic structure. A pure α-phase tantalum film can refer to a tantalum film whose crystal form is entirely α-phase (i.e., with a body-centered cubic structure). A tantalum film can be a thin layer composed of tantalum, achieving the excellent corrosion resistance of metallic tantalum.

[0044] Photoresist: A gel-like substance that undergoes chemical changes when exposed to ultraviolet light or bombarded by an electron beam (i.e., photolithography). The irradiated or bombarded areas will also exhibit significantly different solubility compared to the unirradiated or unbombarded areas, thus enabling the fabrication of the desired pattern.

[0045] Etching refers to the process of removing the exposed portion along the photoresist pattern after photolithography.

[0046] Sputtering is a process in which material on a target is ejected by plasma and deposited onto a substrate.

[0047] Substrate: refers to the substrate on which thin films (such as tantalum films) are deposited, such as silicon (Si) and sapphire substrates mentioned above.

[0048] Target material: refers to the material bombarded by plasma during sputtering, such as tantalum targets made of tantalum or niobium targets made of niobium.

[0049] In related technologies, two methods for growing pure α-phase tantalum films are provided. One method involves heating the substrate to a very high temperature (e.g., greater than 400 degrees Celsius) during tantalum film growth, which is called high-temperature growth. The other method involves first depositing a seed layer (e.g., Nb, TiN, TaN, etc.) several nanometers thick on the substrate, and then growing the tantalum film at low temperature or room temperature, which is called seed layer growth.

[0050] refer to Figure 1For high-temperature growth methods, in order to obtain a pure α-phase tantalum film, the substrate 100, such as Si(001) or Al2O3(0001), needs to be heated to above 400 degrees Celsius (black filling indicates that the substrate 100 is at a high temperature). Then, Ar gas is introduced into the sputtering chamber of the magnetron sputtering equipment. In a high vacuum environment, Ar plasma (Ar ions) is generated by a DC source or AC source. The plasma bombards the tantalum target, thereby sputtering the tantalum and depositing it on the Si(001) or Al2O3(0001) substrate to generate a pure α-phase tantalum film.

[0051] However, the heating and cooling processes of high-temperature growth are extremely time-consuming, resulting in low efficiency in the fabrication of pure alpha-phase tantalum films. Furthermore, in micro / nano fabrication scenarios, photoresist is frequently used to define patterns. Photoresist is often not heat-resistant and can deform or degenerate at high temperatures, leading to process failure. For subsequent components such as tantalum junctions and tantalum air bridges, tantalum films need to be deposited on patterned photoresist. If the substrate needs to be heated, the photoresist will deform due to heat, causing process failure. Additionally, heated photoresist releases impurity gases, which can also compromise the vacuum environment of the sputtering chamber.

[0052] refer to Figure 2 For the seed layer growth method, a seed layer needs to be grown on a substrate 200 such as Si(001) or Al2O3(0001) before growing the tantalum film. The material of the seed layer can be superconducting metals such as Nb, TiN, or TaN. The thickness of the seed layer is about 10 nm. Then, the tantalum film is grown on the seed layer. In this way, a pure α-phase tantalum film can be obtained without heating the substrate.

[0053] However, the seed layer growth method requires multiple targets on a magnetron sputtering device, with at least one target used for growing the seed layer and another for growing the tantalum film. This can lead to cross-contamination between the targets, meaning that while one material is being deposited, the same material may also be deposited on other targets. Furthermore, the use of multiple targets increases the cost of preparing a pure α-phase tantalum film.

[0054] The technical solution provided in this application can directly generate a pure α-phase tantalum film on a substrate at room temperature without heating the substrate to a high temperature or preparing a seed layer on the substrate in advance. This can be used to improve the preparation efficiency of pure α-phase tantalum film and reduce the preparation cost of pure α-phase tantalum film.

[0055] The technical solutions provided in this application are applicable to any scenario requiring the preparation of pure α-phase tantalum films, such as the preparation of the bottom film of chips (e.g., superconducting quantum chips, quantum chips, etc.), the preparation of anti-corrosion films of objects (e.g., chips, components, utensils, etc.), and the preparation of subsequent components such as tantalum junctions and tantalum air bridges of chips. This application does not limit these scenarios.

[0056] The technical solutions provided in this application can be implemented in a tantalum film preparation system, which can be used to prepare metal thin films, such as tantalum films, nitrile films, aluminum films, etc. In this application embodiment, the tantalum film preparation system is used to prepare pure α-phase tantalum films. Optionally, the tantalum film preparation system can be based on magnetron sputtering technology, the working principle of which is to use high-energy plasma to bombard the target material, thereby sputtering the material and forming a thin film on a substrate (such as a substrate placed on the substrate).

[0057] In one example, please refer to Figure 3 This is a schematic diagram of a tantalum film preparation system provided in one embodiment of this application. The tantalum film preparation system 300 may include a sputtering chamber 301, a substrate pedestal 302, a DC source 303, a baffle 304, a target pedestal (not shown), a magnet 305, and a pump system (not shown).

[0058] The sputtering chamber 301 is used to place the target and substrate. The sputtering chamber 301 can form a sealed space, providing a preparation environment for the tantalum film fabrication process. In this embodiment, the sputtering chamber 301 and the pump system are used to provide a preparation environment for the tantalum film fabrication process, such as a vacuum environment or room temperature. Optionally, the sputtering chamber 301 can be evacuated using the pump system of the tantalum film fabrication system 300. This pump system may include a dry pump, a molecular pump, and a cold pump. The dry pump is used to expel air from the sputtering chamber 301 through a dual-scroll disk structure, achieving a maximum vacuum level of ~10. -4 Tolerancing-level molecular pumps are used to draw residual gas molecules to a dry pump using high-speed rotating blades, achieving a maximum vacuum of ~10⁻⁶. -9 The cold pump is used to adsorb gases (such as hydrogen) that are difficult to remove from the sputtering chamber 301 onto its inner wall through cold adsorption, thereby achieving a higher vacuum state in the sputtering chamber 301. Through the pump system, the vacuum level within the sputtering chamber 301 can reach below 5E-10 (i.e., 5 × 10⁻⁶). -10 )Tuo.

[0059] The substrate base 302, baffle 304, target base and magnet 305 can be disposed in the sputtering chamber 301. For example, the substrate base 302 can be disposed in the upper part of the sputtering chamber 301 for placing the substrate, and the substrate can be electrically connected to the substrate base 302; the target base can be disposed in the bottom of the sputtering chamber 301 for placing the target, and the target can be electrically connected to the target base; optionally, the substrate base 302 and the target base are facing each other (or can be adjusted to be facing each other) so that the substrate and the target are facing each other.

[0060] Magnet 305 can be disposed on the target base, such as at the rear of the target base (i.e., near the bottom of the sputtering chamber 301). Magnet 305 forms a magnetic field in the sputtering chamber 301, which can be used to guide the plasma bombarding the target to accumulate and move towards the target.

[0061] The baffle 304 is movable. In the closed state, the baffle 304 forms an isolation between the substrate and the target, such as allowing the substrate and the target to be in separate chambers, or preventing material sputtered from the target from depositing onto the substrate. This embodiment of the application does not limit this. In the open state, the baffle 304 no longer forms an isolation between the substrate and the tantalum target, that is, there is no obstruction between the substrate and the target, and material sputtered from the target can be directly deposited onto the substrate.

[0062] The DC source 303 uses the target material as the cathode and the substrate as the anode. It can achieve electrical connection with the target material and the substrate by connecting the substrate base 302 and the target material base. For example, if the target material base is used as the cathode, the target material is the cathode, and the substrate base 302 is used as the anode, the substrate is the anode. The DC source 303 can be disposed inside or outside the sputtering chamber 301, and the embodiments of this application do not limit this.

[0063] An electric field exists between the target and the substrate under the influence of a DC source 303. This electric field is directed from the substrate towards the target. Electrons fly from the target to the substrate under the influence of the electric field, and are accelerated to a high speed by the electric field. During their flight towards the substrate, the electrons encounter the working gas (such as Ar gas) introduced into the sputtering chamber 301. The high-speed electrons collide with the atoms of the working gas, causing the atoms of the working gas to ionize. As the voltage between the anode and cathode increases, the working gas is broken down, resulting in a glow discharge phenomenon and generating plasma of the working gas. The plasma of the working gas is positively charged and is accelerated from the substrate to the target under the influence of the electric field. The plasma collides with the target, sputtering material that is deposited onto the substrate (0001) to form a thin film.

[0064] Optionally, the tantalum film preparation system 300 also includes a gas introduction device to introduce a working gas (such as Ar gas) into the sputtering chamber 301, which, together with the pump system, maintains the vacuum level in the sputtering chamber 301 during sputtering.

[0065] Optionally, the tantalum film preparation system 300 described above can be implemented as a magnetron sputtering device. This magnetron sputtering device is a device based on magnetron sputtering technology. Its working principle is to use high-energy plasma to bombard the target material, thereby sputtering the material and forming a thin film on the substrate (such as a substrate placed on the substrate).

[0066] It should be noted that, Figure 3 The tantalum film preparation system 300 shown is merely exemplary and illustrative. The embodiments of this application do not limit the structure of the tantalum film preparation system. Any tantalum film preparation system that is applicable to the technical solutions provided in the embodiments of this application should be within the protection scope of the embodiments of this application.

[0067] The technical solutions provided in this application will be described below through method embodiments. For content not described in the embodiments of this application, please refer to the above embodiments, which will not be repeated here.

[0068] Please refer to Figure 4 The diagram illustrates a flowchart of a tantalum film preparation method according to an embodiment of this application. The method may include steps 401 to 402.

[0069] Step 401: Connect the tantalum target and substrate to the two poles of the DC source.

[0070] Tantalum sputtering targets are targets made entirely of tantalum. They are used to prepare tantalum films (also known as tantalum thin films, tantalum coatings, etc.). The purer the tantalum sputtering target, the purer the tantalum film (such as α-phase tantalum film). For example, tantalum sputtering targets can refer to unprocessed tantalum blocks, i.e., high-purity tantalum crystals. Tantalum sputtering targets are widely used in electronics, power, and other fields, such as semiconductor coating, optical coating, decoration, flat panel displays, and functional coatings.

[0071] The substrate can refer to a substrate on which a pure α-phase tantalum film is deposited. For example, for a superconducting quantum chip, the substrate can be the base of the superconducting quantum chip, serving as the substrate for depositing the pure α-phase tantalum film. In one example, the substrate includes an alumina substrate, which refers to a substrate made based on alumina. For example, the substrate in the embodiments of this application includes an Al2O3 substrate, i.e., a sapphire substrate (such as a c-plane sapphire substrate), with the crystal plane oriented as (0001). Tantalum sputtered from a tantalum target is deposited on the Al2O3 substrate to generate a pure α-phase tantalum film. For example, if the sputtered tantalum is uniformly deposited on the Al2O3 substrate, a pure α-phase tantalum film is grown.

[0072] In a feasible example, the lattice constant of the Al2O3 substrate is: (Å), the lattice constant of a pure α-phase tantalum film is It is difficult to grow pure α-phase tantalum films on substrates such as Si(001) at room temperature because the lattice constant of the Si(001) plane is... Its lattice constant mismatch with that of pure α-phase tantalum film is relatively large. In comparison, sapphire substrate has a lattice constant closer to that of pure α-phase tantalum film than Si(001) substrate, which is more conducive to the growth of pure α-phase tantalum film. Therefore, embodiments of this application can also place the lattice constant at... Nearby (e.g.) to The substrate (inner) is used as a substrate for growing pure α-phase tantalum films.

[0073] Connecting the tantalum target and substrate to the two electrodes of a DC source allows the DC source to act on the tantalum target and substrate, generating an electric field between them. The two electrodes of the DC source include a cathode and an anode. Optionally, the DC source can be at least one of the following: a DC current source and a DC voltage source. A DC current source is a circuit or device capable of providing a stable DC current output, such as a constant output current; a DC voltage source is a circuit or device capable of providing a stable voltage output, such as a constant output voltage.

[0074] In one example, the tantalum target can be connected to the cathode of a DC source, and the substrate can be connected to the anode of a DC source. This generates an electric field between the tantalum target and the substrate, with the direction of the electric field pointing from the substrate to the tantalum target. This electric field can cause electrons to fly from the tantalum target to the substrate, thereby achieving magnetron sputtering and providing a basis for sputtering.

[0075] Optionally, the aforementioned pure α-phase tantalum film can be prepared using the aforementioned tantalum film preparation system (such as a magnetron sputtering device). In this system, the DC source can use a tantalum target as the cathode and the substrate as the anode, electrically connecting the tantalum target and the substrate. For example, in the tantalum film preparation system, the DC source uses a target substrate as the cathode and a substrate substrate as the anode, electrically connecting the target substrate and the substrate substrate. Since the tantalum target and the target substrate (metallic material) are electrically conductive, and the substrate and the substrate substrate (metallic material) are electrically conductive, placing the tantalum target on the target substrate and placing the substrate on the substrate substrate connects the tantalum target to the cathode of the DC source and the substrate to the anode of the DC source.

[0076] In some embodiments, the connecting component (such as a metal clip) corresponding to the cathode of the DC source can be directly fixed to the tantalum target, and the connecting component corresponding to the anode of the DC source can be directly fixed to the substrate, thereby connecting the tantalum target to the cathode of the DC source and connecting the substrate to the anode of the DC source.

[0077] Step 402: In a vacuum environment at room temperature, the power of the DC source is adjusted to within the first power range so that the first gas generates a glow discharge phenomenon. The plasma generated by the glow discharge phenomenon of the first gas bombards the tantalum target to sputter tantalum, and the tantalum is deposited on the substrate to generate a pure α-phase tantalum film. The room temperature range is 20 degrees Celsius to 40 degrees Celsius, and the first gas is a non-reactive gas relative to the sputtered tantalum.

[0078] A vacuum environment refers to an environment where air or other gases are evacuated to form a certain pressure range. In the embodiments of this application, the vacuum environment can be provided by the sputtering chamber of a magnetron sputtering device. For example, a vacuum environment is obtained by evacuating the first gas in the sputtering chamber. The evacuation process will be described in detail below and will not be repeated here. A vacuum environment at room temperature means that the vacuum environment is at room temperature. Optionally, the tantalum target, substrate, and first gas are all in a vacuum environment at room temperature.

[0079] Room temperature refers to the temperature of indoor air in a normal indoor environment. In this embodiment, the room temperature range can be 20°C to 40°C, that is, the temperature range of the vacuum environment at room temperature can be 20°C to 40°C, and the temperature range of the substrate at room temperature can be 20°C to 40°C. Maintaining the substrate temperature within 20°C to 40°C allows for the generation of a pure α-phase tantalum film without heating the substrate to a high temperature (e.g., greater than 400°C), which is beneficial for improving the preparation efficiency of the pure α-phase tantalum film. Exemplarily, during the growth of the pure α-phase tantalum film, the magnetron sputtering equipment can be placed in a room temperature environment so that the vacuum environment provided by the sputtering chamber is at room temperature. Room temperature environment refers to an environment at room temperature. For example, during the growth of the pure α-phase tantalum film, the temperature range of the room temperature environment can be set within 20°C to 26°C, such as stabilizing the room temperature environment at around 25°C. This embodiment does not limit this.

[0080] For example, refer to Figure 5 There is no need to heat the substrate 500 to a high temperature or prepare a seed layer on the substrate 500. The tantalum target can be sputtered directly in a vacuum environment at room temperature by the plasma generated by the first gas due to the glow discharge phenomenon. The tantalum is deposited on the substrate 500 to generate a pure α phase tantalum film.

[0081] Optionally, if the magnetron sputtering equipment is in a room temperature environment (i.e., the sputtering chamber is in a room temperature environment and the substrate is also in a room temperature environment), then there is no need to adjust the temperature of the substrate, and pure α-phase tantalum film can be prepared directly; if the magnetron sputtering equipment is not in a room temperature environment, the temperature of the substrate can be maintained within 20 degrees Celsius to 40 degrees Celsius by using the substrate base in the magnetron sputtering equipment, or the environment in which the magnetron sputtering equipment is located can be adjusted to a room temperature environment.

[0082] Optionally, the power of the DC source is equal to the product of voltage and current. The power of the DC source can be adjusted by adjusting the voltage or by adjusting the current. This application does not limit this.

[0083] In one example, the first power range is 200 watts (W) to 300 watts. If the power of the DC source is adjusted to 200 to 300 watts by adjusting the voltage, the first gas will break down as the voltage between the anode and cathode increases, resulting in a glow discharge. For example, the first power range can be set to 250 to 300 watts to ensure that the plasma generated by the glow discharge has sufficient energy to bombard the tantalum target. For instance, if the power of the DC source is adjusted to 300 watts by adjusting the voltage, the first gas will break down as the voltage between the anode and cathode increases, resulting in a glow discharge.

[0084] The first gas is the working gas in the tantalum film preparation process, and it does not react with tantalum. Glow discharge is an electrical discharge phenomenon that occurs in low-pressure gases, i.e., a self-sustaining discharge phenomenon in rarefied gases, which can cause the first gas to generate plasma, such as positively charged plasma.

[0085] In one example, the first gas includes a rare gas, which refers to the gaseous element corresponding to all group 0 elements in the periodic table. This rare gas is non-reactive relative to the sputtered tantalum, meaning it does not react with tantalum. For example, the first gas is argon (Ar). Ar is inert and does not affect the growth of the pure α-phase tantalum film; that is, Ar does not react with tantalum to generate substances other than tantalum, thus not affecting the purity of the tantalum film.

[0086] For example, taking an Al2O3 substrate and Ar gas as an example, refer to Figure 3 An electric field exists between the tantalum target and the Al2O3 substrate under the influence of a DC source 303. This electric field is directed from the Al2O3 substrate towards the tantalum target. Electrons fly from the tantalum target to the Al2O3 substrate under the influence of the electric field, and are accelerated to a high speed by the electric field. During their flight towards the Al2O3 substrate, the electrons encounter Ar gas introduced into the sputtering chamber 301. The high-speed electrons collide with Ar atoms, causing the Ar atoms to ionize. As the voltage of the anode and cathode increases (i.e., the power of the DC source 303 is adjusted to 200 watts to 300 watts), the Ar gas is broken down, resulting in a glow discharge phenomenon, which generates Ar ions (i.e., plasma). These positively charged Ar ions are accelerated from the Al2O3 substrate to the tantalum target under the influence of the electric field. The Ar ions collide with the tantalum target to sputter tantalum, and the tantalum material is deposited on the Al2O3 substrate (0001), forming a pure α-phase tantalum film.

[0087] Alternatively, the growth of pure α-phase tantalum film also requires a suitable vacuum environment, that is, a vacuum environment with a suitable vacuum level. When the tantalum target and substrate are placed in the sputtering chamber of the tantalum film preparation system, the sputtering chamber can be adjusted to a suitable vacuum environment by using a first gas to grow pure α-phase tantalum film.

[0088] In one example, such as Figure 6 As shown, step 403 may be included before step 402.

[0089] Step 403: Continuously introduce the first gas into the sputtering chamber to stabilize the vacuum level of the sputtering chamber within a first vacuum level range, which is 7 × 10⁻⁶. -3 Up to 1×10 -2 Entrust.

[0090] Optionally, the gas introduction device in the tantalum film preparation system is controlled to continuously introduce the first gas into the sputtering chamber. During sputtering, the vacuum level of the sputtering chamber can be maintained jointly by the gas introduction device and the pump system (used to extract gas from the sputtering chamber) of the tantalum film preparation system. For example, the vacuum level of the sputtering chamber can be determined by the flow rate of the first gas and the pumping speed of the pump system. By maintaining the flow rate of the first gas (which is controlled by the gas introduction device) and the pumping speed of the pump system within a certain range, the vacuum level of the sputtering chamber can be stabilized, resulting in a vacuum environment with a suitable vacuum level.

[0091] For example, taking Ar gas as an example, refer to Figure 3 Ar gas is continuously introduced into the sputtering chamber 301 through a gas introduction device (as shown in the upper left corner), and gas is continuously extracted from the sputtering chamber 301 through a pump system (as shown in the lower right corner), so that the vacuum degree of the sputtering chamber 301 is stabilized at 7×10⁻⁶. -3 Up to 1×10 -2 Entrust.

[0092] Optionally, in order to grow a high-quality pure α-phase tantalum film, the sputtering chamber needs to be evacuated to an ultra-high vacuum (e.g., ~10) before sputtering. -10 Up to ~10 -11 This method avoids collisions (or reactions) between the sputtered tantalum and residual impurity gas molecules (such as N2) in the sputtering chamber, which could affect the tantalum deposition process.

[0093] In one example, such as Figure 6 As shown, step 404 may be included before step 403.

[0094] Step 404: Evacuate the sputtering chamber to a second vacuum level range to remove gas molecules from the sputtering chamber. This second vacuum level range is 3 × 10⁻⁶. -10 Up to 5×10-10 Entrust.

[0095] Optionally, the vacuum level of the sputtering chamber is evacuated to the second vacuum level range by the pump system of the tantalum film preparation system. At this time, the gas introduction device of the tantalum film preparation system does not introduce gas into the sputtering chamber.

[0096] For example, refer to Figure 3 The gas is continuously extracted from the sputtering chamber 301 by the pump system (as shown in the lower right corner), so that the vacuum degree of the sputtering chamber 301 reaches 3×10⁻⁶. -10 Up to 5×10 -10 At this time, Ar gas is not introduced into the sputtering chamber 301 through the gas introduction device (as shown in the upper left corner).

[0097] Optionally, the growth of a pure α-phase tantalum film also requires a suitable target-substrate distance. Target-substrate distance refers to the distance between the target and the substrate. In the embodiments of this application, the target-substrate distance can refer to the distance between the tantalum target and the substrate. The target-substrate distance determines the tantalum deposition rate and the tantalum sputtering energy. Different sputtering energies will result in different phases in the tantalum film. A suitable target-substrate distance can grow a pure α-phase tantalum film.

[0098] In one example, the target-substrate distance between the tantalum target and the substrate falls within a first distance range, which is 9 cm to 11 cm. For example, the target-substrate distance between the tantalum target and the substrate can be set to 10 cm.

[0099] Optionally, when the substrate is placed on the substrate base of the tantalum film preparation system and the tantalum target is placed on the target base of the tantalum film preparation system, such as Figure 6 As shown, step 405 may be included before step 403.

[0100] Step 405: If the target-substrate distance is not within the first distance range, adjust the target-substrate distance to within the first distance range by adjusting at least one of the substrate base and the target base.

[0101] For example, the substrate base is fixed and the target base is moved to adjust the target-substrate distance to within a first distance range; the target base is fixed and the substrate base is moved to adjust the target-substrate distance to within the first distance range; the substrate base and the target base are moved simultaneously to adjust the target-substrate distance to within the first distance range.

[0102] Optionally, when the target-substrate distance is within the first distance range, there is no need to adjust the substrate and target base. In one example, during the growth of a pure α-phase tantalum film, the substrate and tantalum target can be set to face each other directly. Facing each other directly means that the center of the substrate and the center of the tantalum target are on the same vertical line. Optionally, during the growth of a pure α-phase tantalum film, the substrate and tantalum target can also be at a certain angle, such as the angle at which tantalum can be deposited on the substrate. The embodiments of this application do not limit the relative angle between the substrate and the tantalum target.

[0103] This application embodiment does not limit the order of steps 404, 405 and 401, and step 403 can be set as the step before step 402.

[0104] In one example, a magnet is placed on the target base, which can be used to guide electrons to converge toward the tantalum target.

[0105] For example, refer to Figure 3 A magnet 305 is disposed behind the tantalum target. The magnet 305 generates a magnetic field in the sputtering chamber 301. The direction of the magnetic field can be from the center of the tantalum target to both sides of the tantalum target. Under the action of the magnetic field, the electrons (negatively charged) that originally flew towards the substrate will be affected by the Lorentz force and change their direction of motion, thus concentrating more near the tantalum target. This can increase the probability of collision between electrons and atoms of the first gas (such as Ar gas), so as to generate more plasma near the tantalum target, thereby improving the sputtering efficiency and thus improving the preparation efficiency of pure α phase tantalum film.

[0106] In one example, considering the presence of some impurities on the surface of the tantalum target, in order to prevent these materials from being sputtered out and deposited on the substrate during the sputtering process, this application embodiment also supports pre-sputtering of the tantalum target to remove some impurities present on the surface of the tantalum target, thereby ensuring that the tantalum deposited on the substrate is of high purity.

[0107] For example, when the tantalum target and substrate are placed in the sputtering chamber of the tantalum film preparation system, pre-sputtering is achieved by adjusting a movable baffle disposed within the sputtering chamber. After step 402, the embodiments of this application may further include the following:

[0108] After the first duration, the baffle is moved to change from the closed state to the open state. In the closed state, the baffle forms an isolation between the substrate and the tantalum target. In the open state, the baffle no longer forms an isolation between the substrate and the tantalum target. The first duration ranges from 30 seconds to 90 seconds.

[0109] The first duration can refer to the duration of pre-sputtering. Sputtering can be divided into pre-sputtering and formal sputtering processes by using a baffle. During the pre-sputtering process, impurities sputtered from the tantalum target are deposited on the baffle. During the formal sputtering process, tantalum sputtered from the tantalum target is deposited on the substrate.

[0110] For example, refer to Figure 3 Before step 402, baffle 304 is moved to the closed state to form an isolation between the substrate and the tantalum target. Then, step 402 is performed to sputter impurities on the tantalum target to deposit onto baffle 304. After 60 seconds, baffle 304 is moved to the open state to stop forming an isolation between the substrate and the tantalum target. The tantalum sputtered on the tantalum target can be directly deposited onto the substrate.

[0111] Optionally, the thickness of the pure α-phase tantalum film is positively correlated with the duration of the formal sputtering process; the longer the duration of the formal sputtering process, the thicker the pure α-phase tantalum film. Thus, the duration of the formal sputtering process can be set according to the required thickness. For example, the thicker the required thickness, the longer the duration of the formal sputtering process can be set. This application embodiment does not limit the duration of the formal sputtering process; it can be set and adjusted according to actual usage requirements.

[0112] In one example, the control range of five parameters—DC source power, first vacuum level range, first distance range, duration of formal sputtering process, and substrate temperature (i.e., room temperature)—can be called the growth condition window for pure α-phase tantalum film. In other words, by controlling the DC source power, first vacuum level range, and first distance range within the growth condition window, a pure α-phase tantalum film of a certain thickness (affected by the duration of formal sputtering process) can be directly generated on the substrate at room temperature.

[0113] In summary, the technical solution provided in this application adjusts the power of the DC source acting on the substrate and the tantalum target to a first power range, so that the tantalum sputtered on the tantalum target has suitable energy to be deposited on the substrate to generate a pure α-phase tantalum film. This enables the direct generation of a pure α-phase tantalum film on the substrate at room temperature without heating the substrate to a high temperature (e.g., greater than 400 degrees Celsius). Compared with the high-temperature long film method in related technologies, this application can effectively reduce the time required for temperature processing during the preparation process, thereby reducing the preparation time of the pure α-phase tantalum film and thus improving the preparation efficiency of the pure α-phase tantalum film.

[0114] Furthermore, since this application does not require the pre-preparation of a seed layer on the substrate (seed layer growth method), it eliminates the need for additional target materials for seed layer preparation and additional target placement processes. Compared to the seed layer growth method, this application saves on the costs associated with the seed layer, thereby reducing the preparation cost of pure α-phase tantalum films. Simultaneously, it avoids the cross-contamination problem between different target materials caused by the seed layer (because there is no isolation between multiple target materials, when one target material is deposited, the same material may also be deposited on other target materials).

[0115] Furthermore, regarding the photoresist fabrication process, since it eliminates the need to heat the substrate to high temperatures, it avoids a series of negative impacts such as deformation, denaturation, and release of impurity gases that easily occur with photoresist at high temperatures. Therefore, the technical solution provided in this application is compatible with processes involving photoresist. Since the technical solution provided in this application does not require heating the substrate to high temperatures, it is also applicable to superconducting quantum chips containing photoresist-based components such as air bridges and Josephson junctions, thereby improving the versatility and applicability of the technical solution provided in this application.

[0116] In some embodiments, taking the growth of a pure α-phase tantalum film on a substrate of a superconducting quantum chip as an example, the embodiments of this application may also include the following:

[0117] 1. Place the substrate of the superconducting quantum chip (i.e., the Al2O3 substrate) and the tantalum target in the sputtering chamber of the magnetron sputtering equipment, which is in a room temperature environment.

[0118] 2. Adjust the target-substrate distance between the substrate of the superconducting quantum chip and the tantalum target to 9 cm to 11 cm.

[0119] 3. Connect the tantalum target to the cathode of the DC source, and connect the substrate of the superconducting quantum chip to the anode of the DC source.

[0120] 4. Evacuate the sputtering chamber to a vacuum level of 3×10⁻⁶. -10 Up to 5×10 -10 Entrust.

[0121] 5. Continuously introduce the first gas (i.e., Ar gas) into the sputtering chamber to stabilize the vacuum level of the sputtering chamber at 7 × 10⁻⁶. -3 Up to 1×10 -2 Entrust.

[0122] 6. Move the baffle in the sputtering chamber to isolate the substrate of the superconducting quantum chip from the tantalum target.

[0123] 7. In a vacuum environment at room temperature, adjust the power of the DC source acting on the tantalum target and substrate to 200 watts to 300 watts so that the first gas produces a glow discharge phenomenon. The temperature range of the room temperature environment is 20 degrees Celsius to 40 degrees Celsius.

[0124] 8. After any duration between 30 and 90 seconds, move the baffle in the sputtering chamber so that the baffle no longer forms an isolation between the substrate of the superconducting quantum chip and the tantalum target. The plasma generated by the first gas due to the glow discharge phenomenon bombards the tantalum target to sputter tantalum, which is deposited on the substrate of the superconducting quantum chip to generate a pure α-phase tantalum film.

[0125] For example, in this embodiment of the application, by setting the target-substrate distance between the substrate of the superconducting quantum chip and the tantalum target to 10 cm, setting the power of the DC source to the range of 200 W to 300 W, setting the vacuum degree of the sputtering chamber to 7E-3 Torr, setting the duration of the pre-sputtering process to 60 s, and setting the duration of the formal sputtering process to 270 s to 280 s, such as setting it to 275 s, a pure α-phase tantalum film with a thickness of 200 nm can be grown on the substrate of the superconducting quantum chip.

[0126] In some embodiments, X-ray diffraction (XRD) is an effective method for detecting crystal structures. Alpha-phase tantalum films have a body-centered cubic structure, while β-phase tantalum films have a tetragonal structure; the diffraction angles of their lattices (the specific arrangement of atoms within the crystal) differ. The XRD data of the tantalum films prepared using the technical solutions provided in the embodiments of this application are as follows: Figure 7 Curve 701 and Figure 8 As shown in curve 801 (the scale of the horizontal axis has been adjusted accordingly), the horizontal axis is in degrees (°) and the vertical axis is in intensity (representing the number of photons collected). Optionally, 38.3° corresponds to the characteristic peak of a pure α-phase tantalum film, and 33.7° corresponds to the characteristic peak of a β-phase tantalum film. As shown in curve 701, there is a significant characteristic peak at 38.3°, which corresponds to the characteristic peak of the (110) crystal orientation of a pure α-phase tantalum film. As shown in curve 801, no obvious characteristic peak is seen at 33.7°, indicating that the tantalum film prepared by the technical solution provided in the embodiments of this application does not have a β phase, indicating that it is a pure α-phase tantalum film.

[0127] In some embodiments, scanning electron microscope (SEM) images can also be used to distinguish between pure α-phase tantalum films and β-phase tantalum films. For example... Figure 9As shown, the pure α-phase tantalum film 901 grown at high temperature exhibits a scattered "rice grain" shape, distributed roughly in pairs at 60° angles. Similarly, the pure α-phase tantalum film 902 obtained through the technical solution provided in this application also exhibits a "rice grain" shape, without any other grain shapes, indicating that its grain phase is a single α-phase. The difference lies in the grain size of the pure α-phase tantalum film 902, which is smaller than that of the pure α-phase tantalum film 901. This may be due to the higher energy at high temperatures, which is more conducive to the formation of larger grains.

[0128] The bottom film is the foundation of a superconducting quantum chip and determines the decoherence performance of the superconducting qubit. The bottom film of a superconducting quantum chip was fabricated using the technical solution provided in this application, and the superconducting quantum chip was further processed, achieving a decoherence time T1 of approximately 270 μs (microseconds). Figure 10 As shown, the scatter sequence 1001 represents the decoherence data of the superconducting quantum chip. The decoherence time T1 is comparable to the decoherence time of the quantum bit under the high-temperature growth method (300 μs), and is higher than the tens of microseconds of the decoherence time of the aluminum-based superconducting quantum bit. This demonstrates that the technical solution provided in the embodiments of this application can be used for the fabrication of high-performance superconducting quantum chips.

[0129] The superconducting quantum chip fabricated based on the pure α-phase tantalum film grown using the technical solution provided in this application exhibits performance comparable to that of pure α-phase tantalum films grown using high-temperature methods. This application eliminates the need for substrate heating; for a 200nm thick pure α-phase tantalum film, the single deposition time can be reduced to less than 0.5 hours. This single deposition time refers to the total time required for the entire fabrication process of the pure α-phase tantalum film, including time spent on vacuuming, adjusting the target-substrate distance, adjusting power, pre-sputtering, and final sputtering. In contrast, the high-temperature growth method requires additional heating and cooling, and for a 200nm thick pure α-phase tantalum film, the single deposition time can be as long as 4-8 hours. Compared to the high-temperature growth method, this application significantly improves the fabrication efficiency of pure α-phase tantalum films and is also applicable to the fabrication of subsequent photoresist-coated components such as tantalum junctions and tantalum air bridges. This application eliminates the need for additional target materials for fabricating the clock layer, thus saving on the fabrication cost of pure α-phase tantalum films and avoiding cross-contamination between different target materials.

[0130] In summary, the technical solution provided in this application has the following advantages:

[0131] 1. Compatible with photoresist coating processes, such as the technical solutions provided in the embodiments of this application, which are applicable to the fabrication of quantum chip components with photoresist, such as Josephson junctions and air bridges.

[0132] 2. No heating or cooling is required, which can shorten the single coating time from 4-8 hours required by the high-temperature growth method to less than 0.5 hours, thereby improving the preparation efficiency of pure α-phase tantalum film.

[0133] 3. Compared with the seed layer growth method, the embodiments of this application do not require multiple target materials, which reduces the preparation cost of pure α phase tantalum film.

[0134] 4. Compared with the seed layer growth method, the embodiments of this application can avoid the problem of cross-contamination between various target materials, which is beneficial to improving the purity of pure α phase tantalum film.

[0135] In some embodiments, the technical solutions provided in this application can be implemented in a tantalum film preparation system, as described above. Figure 11 The tantalum film preparation system 1100 may include a sputtering chamber 1101 and a DC source 1102. The sputtering chamber 1101 may include a target base 1104 and a substrate base 1103.

[0136] Sputtering chamber 1101 provides a preparation space for the preparation process of pure α-phase tantalum film. The sputtering chamber 1101 may include a bottom wall 1101a, a top wall 1101b, and a peripheral wall 1101c. One end of the bottom wall 1101a is connected to one end of the peripheral wall 1101c, and the other end of the top wall 1101b is connected to the other end of the peripheral wall 1101c, forming a preparation space that can be made into a closed space.

[0137] A target base 1104 is used to place a tantalum target; a substrate base 1103 is used to place a substrate. Optionally, the target base 1104 may be disposed on the bottom wall 1101a, and the substrate base 1103 may be disposed on the top wall 1101b, such that the target base 1104 is upright on the bottom wall 1101a, and the substrate base 1103 is inverted on the top wall 1101b. In a feasible example, the target base 1104 may also be disposed on the top wall 1101b, and the substrate base 1103 may be disposed on the bottom wall 1101a; this embodiment of the application is not limited in this respect. Optionally, the substrate includes an Al2O3 substrate.

[0138] In one example, the substrate base 1103 includes a sliding tray, which is embedded in the substrate base 1103 in a "drawer" style, facing the bottom wall 1101a. The tray is provided with locking screws for securing the substrate to the tray. If the tray is removed from the substrate base 1103, the substrate can be secured to the side of the tray facing the bottom wall 1101a using the locking screws. Once the tray is pushed into the substrate base 1103, the substrate placement is complete. In a feasible example, the substrate base 1103 may include a clamp with an opening facing the bottom wall 1101a for clamping the substrate, thereby securing it to the substrate base 1103. The tray and the substrate are electrically conductive. Optionally, the tray can be moved manually or automatically by the control system of the tantalum film fabrication system 1100 (e.g., implemented as a microcomputer) according to control commands; this embodiment does not limit the scope of this application.

[0139] For example, in response to a control command for retrieving the tray, the control system of the tantalum film preparation system 1100 controls the tray to slide out of the substrate base 1103, and in response to a control command for advancing the tray, the control system of the tantalum film preparation system 1100 controls the tray to slide into the substrate base 1103. This control command can be triggered by a corresponding switch (such as a virtual switch, a real switch, etc.).

[0140] The target base 1104 may include a platform facing the top wall 1101b for placing a tantalum target. The platform and the tantalum target are electrically conductive.

[0141] Optionally, the position of the target base 1104 in the sputtering chamber 1101 can be adjusted, and the position of the substrate base 1103 in the sputtering chamber 1101 can also be adjusted, such as the target base 1104 and the substrate base 1103 both supporting adjustment in four directions: up, down, left and right.

[0142] In one example, during the preparation of a pure α-phase tantalum film, the target-substrate distance between the tantalum target and the substrate falls within a first distance range, which is 9 cm to 11 cm. If the target-substrate distance does not fall within this first distance range, at least one of the target base 1104 and the substrate base 1103 can be moved to adjust the target-substrate distance to within the first distance range. Optionally, the target base 1104 and the substrate base 1103 can be moved manually or automatically by the control system of the tantalum film preparation system 1100 based on input; this embodiment does not limit this. For example, the control system of the tantalum film preparation system 1100 may automatically move at least one of the target base 1104 and the substrate base 1103 according to the first distance range input by the user to adjust the target-substrate distance to within the first distance range.

[0143] A DC source 1102 is used to connect the tantalum target and the substrate. The DC source 1102 can be placed inside or outside the sputtering chamber 1101; this embodiment does not limit its placement. The cathode of the DC source 1102 is connected to the tantalum target, and the anode is connected to the substrate. In one example, the cathode of the DC source 1102 is electrically connected to the target base 1104, and the anode is electrically connected to the substrate base 1103. By placing the substrate on the substrate base 1103 and the tantalum target on the target base 1104, the substrate can be used as the anode, and the tantalum target as the cathode.

[0144] Optionally, the DC source 1102 is also used to adjust the power to a first power range in a vacuum environment at room temperature so that the first gas generates a glow discharge phenomenon. The plasma generated by the glow discharge phenomenon of the first gas bombards the tantalum target to sputter tantalum, and the tantalum is deposited on the substrate to generate a pure α-phase tantalum film. The room temperature range is 20 degrees Celsius to 40 degrees Celsius, and the first gas is a non-reactive gas relative to the sputtered tantalum.

[0145] In one example, the power of the DC source 1102 can be adjusted via the control panel (such as a panel that allows input of parameters such as voltage, current, and power) corresponding to the tantalum film preparation system 1101. For example, the control system corresponding to the tantalum film preparation system 1101 can obtain the first power range input by the user through the control panel and adjust the voltage of the DC source 1102 to adjust the power of the DC source 1102 to within the first power range.

[0146] The power of the DC source 1102 can also be adjusted via a corresponding control switch (such as a switch for controlling voltage, current, power, etc.). For example, the user can increase the voltage of the DC source 1102 by controlling the voltage switch to adjust the power of the DC source 1102 to within the first power range. This application embodiment does not limit the method for adjusting the power of the DC source 1102.

[0147] Optionally, the first power range is 200 watts to 300 watts, and the first gas is argon.

[0148] In one example, the tantalum film preparation system 1100 may further include a pump system 1108. The pump system 1108 is located outside the sputtering chamber 1101, but is connected to the corresponding preparation space of the sputtering chamber 1101 via a gas pipe. For example, a vent is provided on the peripheral wall 1101c to connect to the gas pipe of the pump system 1108. Optionally, the pump system may include a dry pump, a molecular pump, and a cold pump. The dry pump is used to expel air from the sputtering chamber 1101 through a dual-scroll disk structure, achieving a maximum vacuum level of ~10⁻⁶. -4Tolerancing-level molecular pumps are used to draw residual gas molecules to a dry pump using high-speed rotating blades, achieving a maximum vacuum of ~10⁻⁶. -9 The cold pump is used to adsorb gases (such as hydrogen) that are difficult to remove from the sputtering chamber 1101 onto its inner wall through cold adsorption, thereby achieving a higher vacuum state in the sputtering chamber 1101. Through the pump system 1108, the vacuum level within the sputtering chamber 1101 can reach below 5E-10 (i.e., 5 × 10⁻⁶). -10 )Tuo.

[0149] In this embodiment, the pump system 1108 is used to evacuate the sputtering chamber 1101 to provide a preparation environment, i.e., a vacuum environment, for the preparation of the pure α-phase tantalum film. In one example, before growing the pure α-phase tantalum film, the pump system 1108 can be used to evacuate the vacuum level of the sputtering chamber 1101 to a second vacuum level range to remove gas molecules from the sputtering chamber 1101. This second vacuum level range is 3 × 10⁻⁶. -10 Up to 5×10 -10 Entrust.

[0150] Optionally, the pumping speed of the pump system 1108 can be adjusted manually or automatically by the control system of the tantalum film preparation system 1100 based on input. This application embodiment does not limit this.

[0151] The sputtering chamber 1101 is also equipped with a vacuum gauge, which is used to measure the vacuum level of the sputtering chamber 1101. The vacuum gauge can be used to display the vacuum level value for user viewing, and can also be used to upload the measured vacuum level to the control system of the tantalum film preparation system 1100, which will then display it to the user. The embodiments of the application do not limit this.

[0152] For example, the control system of the tantalum film preparation system 1100 controls the pumping speed of the pump group system 1108 according to the vacuum degree returned by the vacuum gauge, so as to control the vacuum degree of the sputtering chamber 1101 within a second vacuum degree range, which can be input to the control system by the user.

[0153] Before growing a pure α-phase tantalum film, the sputtering chamber 1101 is evacuated to an ultra-high vacuum (e.g., ~10) using the pump system 1108. -10 Up to ~10 -11 This avoids collisions (or reactions) between the sputtered tantalum and residual impurity gas molecules (such as N2) in the sputtering chamber 1101, which would affect the tantalum deposition process.

[0154] In one example, the tantalum film preparation system 1100 may further include a gas introduction device 1107. The gas introduction device 1107 is used to introduce working gas into the sputtering chamber 1101. This gas introduction device 1107 is located outside the sputtering chamber 1101, but it is also connected to the corresponding preparation space of the sputtering chamber 1101 via a gas pipe, such as by another gas hole provided on the peripheral wall 1101c to communicate with the gas introduction device 1107.

[0155] Optionally, the gas introduction device 1107 includes a gas pipe and a high-pressure cylinder. One end of the gas pipe is connected to the other gas port mentioned above, and the other end of the gas pipe is connected to the high-pressure cylinder (e.g., around 15 MPa), which contains the first gas. A pressure-reducing valve is installed on the gas pipe to adjust the pressure to around 0.2 MPa, thereby controlling the flow rate of the first gas flowing into the sputtering chamber 1101. The pressure-reducing valve is equipped with a flow meter for measuring the flow rate of the first gas. This flow meter sends the measured flow rate to the control system of the tantalum film preparation system 1100. The control system of the tantalum film preparation system 1100 controls the pressure-reducing valve based on the flow rate to precisely control the flow rate of the first gas flowing into the sputtering chamber 1101.

[0156] During the formation of a pure α-phase tantalum film, the gas introduction device 1107 can be used to continuously introduce a first gas into the sputtering chamber 1101 to achieve the sputtering process of the tantalum target. Optionally, during the formation of the pure α-phase tantalum film, the gas introduction device 1107 can also be used to stabilize the vacuum level of the sputtering chamber 1101 within a first vacuum level range, which is 7 × 10⁻⁶. -3 Up to 1×10 -2 Entrust.

[0157] For example, in the process of generating a pure α-phase tantalum film, a gas introduction device 1107 is used to continuously introduce a first gas into the sputtering chamber 1101, and a pump system 1108 is used to continuously extract gas from the sputtering chamber 1101 so that the vacuum degree of the sputtering chamber 1101 is stabilized within the first vacuum degree range. That is, the control system of the tantalum film preparation system 1100 can maintain the flow rate of the first gas and the pumping speed of the gas in a dynamic balance by controlling the gas introduction device 1107 and the pump system 1108 so that the vacuum degree of the sputtering chamber 1101 is stabilized within the first vacuum degree range.

[0158] In one example, the sputtering chamber 1101 further includes a movable baffle 1105, which is disposed between the substrate base 1103 and the target base 1104. The baffle 1105 can be switched between a closed state and an open state via a pneumatic valve. In the closed state, the baffle 1105 forms an isolation between the substrate and the tantalum target; in the open state, the baffle 1105 no longer forms an isolation between the substrate and the tantalum target.

[0159] Optionally, the pneumatic valve is controlled by the control system of the tantalum film preparation system 1100. For example, after acquiring the opening time input by the user, the tantalum film preparation system 1100 controls the pneumatic valve to switch the baffle 1105 to the open state at the opening time; after acquiring the closing time input by the user, the tantalum film preparation system 1100 controls the pneumatic valve to switch the baffle 1105 to the closed state at the closing time.

[0160] Optionally, after the tantalum target is sputtered, the baffle 1105 is also used to move after a first time period to enter the open state from the closed state. The first time period ranges from 30 seconds to 90 seconds. This can prevent material on the surface of the tantalum target from being sputtered out and deposited on the substrate during the sputtering process, so that the tantalum deposited on the substrate is of high purity.

[0161] In one example, the sputtering chamber 1101 also includes a magnet 1106, which is located behind the target base 1104, such as on the side of the target base 1106 near the bottom wall 1101b. During sputtering, the magnet 1106 is used to guide electrons to converge and move towards the tantalum target. The magnet 1106 can be used to form a magnetic field in the sputtering chamber 110. The direction of the magnetic field can be from the center of the target base 1104 to both sides of the target base 1104. Under the action of the magnetic field, electrons (negatively charged) that were originally flying towards the substrate will be affected by the Lorentz force and change their direction of motion, thus concentrating more near the target base 1104 (i.e., the tantalum target). This increases the probability of collisions between electrons and atoms of the first gas (such as Ar gas), generating more plasma, thereby improving sputtering efficiency and thus improving the preparation efficiency of pure α-phase tantalum film.

[0162] In summary, by controlling the power of the DC source, the vacuum level of the sputtering chamber, and the target-substrate distance within a certain range, a pure α-phase tantalum film can be directly generated on the substrate at room temperature.

[0163] In some embodiments, the tantalum film preparation system described above can be implemented as a magnetron sputtering device. The technical solution provided in this application embodiment can be automatically completed by the magnetron sputtering device. After placing the substrate (i.e., the Al2O3 substrate) on the substrate base of the magnetron sputtering device and placing the tantalum target on the target base of the magnetron sputtering device, the embodiments of this application may further include the following:

[0164] 1. When the target-base distance between the substrate and the tantalum target is not within the first distance range, control the movement of at least one of the substrate base and the target base to adjust the target-base distance to within the first distance range, which is 9 cm to 11 cm.

[0165] 2. Control the pump system consisting of dry pump, molecular pump, and cold pump to evacuate the sputtering chamber of the magnetron sputtering equipment to a vacuum level of 3×10⁻⁶. -10 Up to 5×10 -10 Entrust.

[0166] 3. Control the gas introduction device to continuously introduce the first gas (i.e., Ar gas) into the sputtering chamber, and control the pump system to continuously evacuate the sputtering chamber to stabilize the vacuum level of the sputtering chamber at 7×10⁻⁶. -3 Up to 1×10 -2 This means that the sputtering chamber must be provided with a vacuum environment at room temperature. Specifically, the magnetron sputtering equipment operates within this room temperature environment, which ranges from 20 to 40 degrees Celsius.

[0167] 4. Control the movement of the baffle in the sputtering chamber so that the baffle forms an isolation between the substrate and the tantalum target.

[0168] 5. In a vacuum environment at room temperature, control the DC power applied to the tantalum target and substrate, adjusting the power to between 200 watts and 300 watts to induce a glow discharge in the first gas. The tantalum target is connected to the cathode of the DC power source, and the substrate is connected to the anode of the DC power source.

[0169] 6. After any duration between 30 and 90 seconds, the baffle is moved so that it no longer forms an isolation between the substrate and the tantalum target. The plasma generated by the first gas due to the glow discharge phenomenon bombards the tantalum target to sputter tantalum, which is deposited on the substrate to form a pure α-phase tantalum film.

[0170] In summary, supporting the automated preparation of pure α-phase tantalum films using magnetron sputtering equipment is beneficial for further improving the preparation efficiency of pure α-phase tantalum films and avoiding the problems of error and inaccurate control caused by manual methods, thereby improving the preparation accuracy of pure α-phase tantalum films.

[0171] In some embodiments, a chip is also provided, wherein the underlying film on the chip is prepared by the tantalum film preparation method described above.

[0172] Alternatively, the chip can be implemented as a superconducting quantum chip, a quantum chip, etc.

[0173] In some embodiments, an apparatus is also provided, the apparatus including a chip, wherein the underlying film on the chip is prepared by the tantalum film preparation method described above.

[0174] It should be noted that, in this application embodiment, before and during the collection of user-related data, a prompt interface, pop-up window, or voice prompt message can be displayed. This prompt interface, pop-up window, or voice prompt message is used to inform the user that their relevant data is being collected. This ensures that the application only begins executing the steps related to acquiring user-related data after receiving confirmation from the user regarding the prompt interface or pop-up window; otherwise (i.e., without receiving confirmation from the user), the steps to acquire user-related data end, meaning no user-related data is acquired. In other words, all user data collected in this application is processed strictly in accordance with the requirements of relevant national laws and regulations. The acquisition of informed consent or separate consent from the personal information subject is conducted with the user's consent and authorization. Subsequent data use and processing are carried out within the scope of laws and regulations and the authorization of the personal information subject. Furthermore, the collection, use, and processing of relevant user data must comply with the relevant laws, regulations, and standards of the relevant countries and regions. For example, the target-base distance, power, first vacuum range, and second vacuum range involved in this application are all obtained with full authorization.

[0175] It should be understood that "multiple" as used herein refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. Furthermore, the step numbers described herein are merely illustrative of one possible execution order. In some other embodiments, the steps may not be executed in numerical order, such as two steps with different numbers being executed simultaneously, or two steps with different numbers being executed in the reverse order of the illustration. This application does not limit this.

[0176] The above description is merely an exemplary embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a tantalum film, characterized in that, The method includes: Connect the tantalum target and substrate to the two poles of a DC source; In a vacuum environment at room temperature, the power of the DC source is adjusted to a first power range so that the first gas produces a glow discharge phenomenon. The plasma generated by the glow discharge phenomenon bombards the tantalum target to sputter tantalum, and the tantalum is deposited on the substrate to generate a pure α-phase tantalum film. The room temperature range is 20 degrees Celsius to 40 degrees Celsius, and the first gas is a non-reactive gas relative to the sputtered tantalum.

2. The method according to claim 1, characterized in that, The connection of the tantalum target and substrate to the two poles of the DC source includes: The tantalum target is connected to the cathode of the DC source, and the substrate is connected to the anode of the DC source.

3. The method according to any one of claims 1 to 2, characterized in that, The first power range is 200 watts to 300 watts.

4. The method according to any one of claims 1 to 3, characterized in that, The first gas includes rare gases.

5. The method according to claim 4, characterized in that, The first gas is argon.

6. The method according to any one of claims 1 to 5, characterized in that, The tantalum target and the substrate are placed in the sputtering chamber of the tantalum film preparation system, and a movable baffle is provided in the sputtering chamber; After adjusting the power of the DC source to within the first power range in a vacuum environment at room temperature, the method further includes: After the first period of time, the baffle is moved so that the baffle changes from the closed state to the open state; In the closed state, the baffle forms an isolation between the substrate and the tantalum target; in the open state, the baffle no longer forms an isolation between the substrate and the tantalum target; and the first duration ranges from 30 seconds to 90 seconds.

7. The method according to any one of claims 1 to 6, characterized in that, The substrate includes an alumina substrate.

8. The method according to claim 7, characterized in that, The substrate is an Al2O3 substrate.

9. The method according to any one of claims 1 to 8, characterized in that, The tantalum target and the substrate are placed in the sputtering chamber of the tantalum film preparation system; Before adjusting the power of the DC source acting on the tantalum target and the substrate to within a first power range in a vacuum environment at room temperature, the method further includes: The first gas is continuously introduced into the sputtering chamber to stabilize the vacuum level of the sputtering chamber within a first vacuum level range, which is 7 × 10⁻⁶. -3 Up to 1×10 -2 Entrust.

10. The method according to claim 9, characterized in that, Before continuously introducing the first gas into the sputtering chamber to stabilize the vacuum level of the sputtering chamber within a first vacuum level range, the method further includes: The vacuum level in the sputtering chamber is evacuated to within a second vacuum level range to remove gas molecules from the sputtering chamber. The second vacuum level range is 3 × 10⁻⁶. -10 Up to 5×10 -10 Entrust.

11. The method according to any one of claims 1 to 10, characterized in that, The target-substrate distance between the tantalum target and the substrate falls within a first distance range, which is 9 cm to 11 cm.

12. The method according to claim 11, characterized in that, The substrate is placed on the substrate base of the tantalum film preparation system, and the tantalum target is placed on the target base of the tantalum film preparation system; Before adjusting the power of the DC source to within the first power range in a vacuum environment at room temperature, the method further includes: If the target-base distance is not within the first distance range, the target-base distance can be adjusted to be within the first distance range by adjusting at least one of the substrate base and the target base.

13. The method according to claim 12, characterized in that, A magnet is provided on the target base, and the magnet is used to guide electrons to gather and move toward the tantalum target.

14. A tantalum film preparation system, characterized in that, The tantalum film fabrication system includes a sputtering chamber and a DC source, wherein the sputtering chamber includes a target substrate and a substrate substrate; The target base is used to place the tantalum target. The substrate base is used to place the substrate; The DC source is used to connect the tantalum target and the substrate; in a vacuum environment at room temperature, the power is adjusted to a first power range so that the first gas generates a glow discharge phenomenon, and the plasma generated by the first gas due to the glow discharge phenomenon bombards the tantalum target to sputter tantalum, and the tantalum is deposited on the substrate to generate a pure α phase tantalum film. The room temperature range is 20 degrees Celsius to 40 degrees Celsius, and the first gas is a non-reactive gas relative to the sputtered tantalum.

15. A chip, characterized in that, The underlying film on the chip is prepared by means of the method described in any one of claims 1 to 13.

16. The chip according to claim 15, characterized in that, The chip is a quantum chip.

17. A device, characterized in that, The device includes a chip, the underlying film on which is prepared by means of the method described in any one of claims 1 to 13.

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