A multi-component oxide thin film, a method for preparing the same, and an application thereof

Abstract

The application belongs to the technical field of semiconductor material preparation, and relates to a multi-element oxide film and a preparation method and application thereof. In view of the technical problem that the multi-element oxide film is difficult to be prepared uniformly in a large area in the prior art, the application provides a preparation method of the multi-element oxide film, which is prepared by molecular beam epitaxy co-evaporation and comprises the following steps: placing a substrate in a molecular beam epitaxy co-evaporation preparation cavity, and vacuumizing the cavity; sequentially depositing a YSZ buffer layer and a CeO2 buffer layer from bottom to top in the cavity, and obtaining a substrate containing the buffer layers by controlling electron beam automatic evaporation through a film thickness gauge; depositing a YBCO film on the substrate containing the buffer layers by co-evaporating yttrium, copper and barium fluoride, and obtaining a multi-element oxide film with good large-area uniformity by co-evaporating the Y evaporation source, the Cu evaporation source and the Ba evaporation source through the film thickness gauge. The application further provides the multi-element oxide film and application thereof.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor material preparation technology, specifically relating to a multi-component oxide thin film, its preparation method, and its application. Background Technology

[0002] The development of evaporation-based multi-component oxide thin films stemmed from the fact that early single-oxide thin films could not meet the demands of devices for miniaturization, high performance, and multi-functional integration. While early single oxides such as SiO2 and pure TiO2 were widely used in electronic insulation and photocatalysis, as chip manufacturing processes entered below 45 nm, SiO2 gate dielectrics suffered from severe leakage current due to their excessive thinness; pure TiO2 photocatalysts only responded to ultraviolet light and could not efficiently utilize solar energy; and indium tin oxide (ITO) transparent electrodes in flexible displays were prone to breakage due to insufficient mechanical stability. These performance bottlenecks spurred the development of multi-component oxide thin films. Through the synergy of different elements, high dielectric properties, broad spectral response, and bending resistance can be customized to adapt to more complex device functions.

[0003] The evolution of preparation technology revolves around solving problems such as "difficulty in controlling the composition of multi-component oxides and the inability to evaporate refractory materials." Early methods used single-source thermal evaporation directly heated and vaporized multi-component oxide powders. However, due to the large differences in the saturated vapor pressure of each element (e.g., the vapor pressure of Pb in lead zirconate titanate is much higher than that of Zr and Ti), the film composition easily deviates from the design value. Furthermore, heating sources such as tungsten boats can react with the material and introduce impurities, and even fail to evaporate refractory materials with melting points exceeding 2700 ℃, such as HfO2 and ZrO2. To overcome these limitations, multi-source co-evaporation and electron beam evaporation technologies have emerged. Multi-source co-evaporation independently controls the evaporation rate of each metal / simple oxide source (combined with a quartz crystal monitor for real-time adjustment), but has a large thickness error and large stoichiometric fluctuations. Electron beam evaporation, on the other hand, uses a high-energy electron beam to directly bombard the material, avoiding heating source contamination with "localized high temperature," and can also vaporize refractory materials. However, a single crucible can only evaporate one type of material at a time, and beam spots interfere with each other during multi-source co-evaporation, resulting in large stoichiometric errors.

[0004] Meanwhile, multi-source co-evaporation and electron beam evaporation technologies also need to complement methods such as magnetron sputtering, sol-gel, and pulsed laser deposition (PLD): Although magnetron sputtering can prepare films with high adhesion, the sputtering yield of multi-component materials varies greatly, and it is difficult to achieve large-area uniform film preparation for complex multi-component oxide materials (such as YBCO multi-component oxides), resulting in a slow growth rate; sol-gel has low cost but is prone to film cracking and requires high-temperature annealing, making it difficult to prepare multi-layer structures; pulsed laser deposition can accurately replicate target material components, but the deposition rate is slow and it is difficult to adapt to large-area production.

[0005] Chinese invention patent application publication number CN101295560A, filed on April 23, 2007, entitled "Preparation Method of Multilayer Insulator and YBCO Coated Conductor Grown on Metal Substrate," discloses a method for growing a multilayer insulating layer and a YBCO coated conductor on a metal substrate. The method involves growing a multilayer cubic textured oxide insulating layer and a superconducting layer on a metal substrate with a cubic texture. The insulating layer on the metal substrate consists of three layers sequentially: a yttrium oxide film, a yttrium-stabilized zirconium dioxide film, and a cerium dioxide film. The superconducting layer is YBCO, grown on the insulating layer. This method uses magnetron sputtering to grow each film. However, for preparing complex oxides like YBCO, there are inherent technical difficulties and limitations in achieving large-area uniform deposition.

[0006] The core challenge currently facing the technology is the poor large-area uniformity of thin films in complex multi-component systems. Therefore, there is an urgent need to provide a method for preparing multi-component oxide thin films that enables real-time monitoring of the elements in the multi-component oxide thin film during the preparation process, thereby producing multi-component oxide thin films with good large-area uniformity. Summary of the Invention

[0007] 1. The problem to be solved

[0008] To address the technical problem of difficulty in preparing large-area uniform multi-component oxide thin films in existing technologies, this application provides a method for preparing multi-component oxide thin films, solving the problem of difficulty in preparing large-area uniform multi-component oxide thin films. Furthermore, this application also provides an application of the multi-component oxide thin film.

[0009] 2. Technical Solution

[0010] To achieve the above objectives, the provided technical solution is as follows:

[0011] The first aspect of this invention provides a method for preparing a multi-component oxide thin film, which is prepared by molecular beam epitaxy co-evaporation, comprising the following steps:

[0012] The substrate is placed in a molecular beam epitaxy co-evaporation preparation cavity, and the cavity is evacuated.

[0013] In a molecular beam epitaxial co-evaporation preparation chamber, YSZ buffer layer and CeO2 buffer layer are deposited sequentially from bottom to top on the substrate. Electron beam automatic evaporation is controlled by a film thickness gauge to obtain a substrate containing buffer layers.

[0014] YBCO thin film deposition was performed by co-evaporating yttrium, copper and barium fluoride on the substrate containing the buffer layer. The co-evaporation of the Y evaporation source, Cu evaporation source and Ba evaporation source was controlled by a film thickness gauge to obtain a multi-element oxide thin film.

[0015] The non-uniformity of the multi-element oxide film is ≤3%.

[0016] Yttrium Barium Copper Oxide (YBCO).

[0017] Preferably, the non-uniformity of the multi-element oxide film is ≤2%.

[0018] Most preferably, the non-uniformity of the multi-element oxide film is ≤1%.

[0019] Ozone is preferably introduced during the co-evaporation process.

[0020] Ozone is a triatomic molecule with a bond energy much lower than that of oxygen. It is also more polar and decomposes more easily into oxygen (O2) and monatomic oxygen (O). Monatomic oxygen has extremely strong oxidizing properties, which leads to ozone also having extremely strong oxidizing properties. This makes it easier for deposited multi-element metal films to oxidize into multi-element oxide films.

[0021] Furthermore, the substrate is placed on a sample disk within the molecular beam epitaxy co-evaporation preparation chamber, the sample disk rotating at a speed of 0.5 r / s to 5 r / s; the vacuum level of the chamber is 1 × 10⁻⁶. -8 mbar~9×10 -8 mbar.

[0022] The sample disk rotates at a speed of 0.5 r / s to 5 r / s. The high-speed rotation can compensate for the uneven spatial flux distribution of the evaporation source, ensuring the macroscopic and microscopic uniformity of the film in terms of thickness and composition. The periodic reorientation caused by the rotation helps atoms migrate on the substrate surface to find better lattice positions, reduce defects, and promote high-quality epitaxy.

[0023] Preferably, the rotation speed of the sample disk is 1 r / s to 5 r / s.

[0024] Most preferably, the rotational speed of the sample disk is 2.5 r / s to 4.5 r / s.

[0025] Vacuum degree is 1×10 -8 mbar~9×10 -8 mbar, a vacuum level within this range provides an ultra-clean environment for the substrate, preventing impurity adsorption and serving as a prerequisite for atomic-level epitaxial growth; for YBCO multi-element oxides, oxygen needs to be precisely introduced, and an ultra-high vacuum background is the basis for precisely controlling the partial pressure of trace reactive gases.

[0026] Furthermore, the deposition temperatures of the YSZ buffer layer and the CeO2 buffer layer are 80 ℃~100 ℃, and the deposition temperature of the YBCO thin film is 850 ℃~950 ℃.

[0027] The buffer layer is deposited at a temperature of 80 ℃ to 100 ℃. At this temperature, the diffusion reaction between the substrate and the deposited oxide atoms is greatly suppressed, avoiding the formation of amorphous or harmful interface compounds, thus ensuring the interface quality of subsequent epitaxial growth. The YBCO thin film is deposited at a temperature of 850 ℃ to 950 ℃. The high temperature provides sufficient surface migration ability for the deposited Y, Ba, Cu, and O atoms, enabling them to achieve the correct crystal structure and oxygen content through epitaxial growth.

[0028] Furthermore, the evaporation rates of the YSZ buffer layer deposition and the CeO2 buffer layer deposition are 3 Å / s to 5 Å / s, and the PID parameters of the YSZ buffer layer deposition and the CeO2 buffer layer deposition are: proportional P = 30 to 60, integral I = 4 to 16, and derivative D = 1 to 4; the thickness of the YSZ buffer layer is 100 nm to 200 nm; and the thickness of the CeO2 buffer layer is 10 nm to 40 nm.

[0029] The evaporation rate of the buffer layer deposition is 3 Å / s to 5 Å / s. This rate can quickly form a stable and dense physical isolation layer, avoiding the excessive proportion of impurity adsorption due to a rate that is too low (e.g., <3 Å / s) or the insufficient atomic migration and increased lattice defects due to a rate that is too high (e.g., >10 Å / s).

[0030] PID parameter control ensures that the evaporation rate remains highly stable during long-term deposition, which is beneficial for obtaining uniform film thickness.

[0031] Preferably, the PID parameters for the YSZ buffer layer deposition and the CeO2 buffer layer deposition are: proportional P = 30~50, integral I = 4~12, and derivative D = 1~3.

[0032] Furthermore, the annealing temperature after the deposition of the YSZ buffer layer and the CeO2 buffer layer is 700 ℃~800 ℃, and the time is 1 h~2 h.

[0033] Furthermore, the evaporation rate of the co-evaporation deposition of yttrium, copper, and barium fluoride is 0.3 Å / s to 0.8 Å / s, and the PID parameters of the co-evaporation deposition of yttrium, copper, and barium fluoride are: proportional P is 30 to 60, integral I is 4 to 16, and differential D is 1 to 4; the thickness of the YBCO film is 500 nm to 600 nm.

[0034] The evaporation rate of co-evaporation deposition of yttrium, copper and barium fluoride is 0.3 Å / s to 0.8 Å / s, which is an extremely low deposition rate. This allows for precise atomic-level stoichiometric control of the three metal elements (Y, Ba, Cu) in YBCO thin films, meeting the requirements for large-area uniformity of multi-element oxide thin films.

[0035] Furthermore, after the co-evaporation deposition, a high-temperature annealing is first performed at a temperature of 900 ℃ to 1000 ℃ for 4 h to 5 h, followed by a low-temperature annealing at a temperature of 400 ℃ to 500 ℃ for 1 h to 2 h.

[0036] First, high-temperature annealing is performed. Only sufficiently high temperatures (>900 ℃) can provide the enormous energy to drive complex chemical reactions and crystal nucleation and growth. Long-term holding at high temperatures ensures complete reaction, thorough decomposition of fluorides, and full growth of YBCO grains. Then, low-temperature annealing is performed to allow oxygen atoms to diffuse into the crystal lattice and arrange themselves in an orderly manner, optimizing the oxygen content and forming an orthorhombic phase.

[0037] Furthermore, it also includes the deposition of contact electrodes on YBCO thin films.

[0038] Preferably, the contact electrode is obtained by evaporating the Ag electrode using an evaporation source controlled by a film thickness gauge.

[0039] Preferably, the contact electrode is obtained by two evaporation depositions, the first evaporation deposition having an evaporation rate of 0.1 Å / s and a thickness of 30 nm; the second evaporation deposition having an evaporation rate of 0.5 Å / s and a thickness of 70 nm.

[0040] The first evaporation deposition rate is relatively slow at 0.1 Å / s, allowing metal atoms to reach the YBCO surface with lower kinetic energy, greatly reducing bombardment damage to the superconducting surface lattice and electronic states. The thickness is 30 nm, which is sufficient to form a continuous and dense film, covering the surface and establishing reliable electrical contacts, while maintaining process efficiency. The second evaporation deposition rate is accelerated to 0.5 Å / s, which improves deposition efficiency and shortens process time based on the existing thin layer. The thickness is increased to 70 nm, providing sufficient mechanical strength and structural integrity.

[0041] The second aspect of the present invention provides a multi-component oxide thin film prepared by the preparation method described in the first aspect of the present invention.

[0042] The third aspect of the present invention provides the application of the multi-component oxide thin film described in the second aspect of the present invention, wherein the multi-component oxide thin film is applied in the preparation of semiconductor devices or high-performance energy storage materials.

[0043] 3. Beneficial effects

[0044] Compared with existing known technologies, the technical solution provided by this invention has the following beneficial effects:

[0045] (1) A method for preparing a multi-element oxide thin film according to the present invention is to prepare it by molecular beam epitaxy co-evaporation, wherein the substrate is placed in a molecular beam epitaxy co-evaporation preparation cavity and the cavity is evacuated;

[0046] In a molecular beam epitaxy co-evaporation preparation chamber, YSZ buffer layer and CeO2 buffer layer are deposited sequentially from bottom to top on the substrate to obtain a substrate containing a buffer layer; the preparation of a buffer layer between the substrate and the YBCO thin film can reduce lattice mismatch, suppress interfacial reactions, and guide epitaxial growth.

[0047] YBCO thin films were deposited on the CeO2 buffer layer containing the buffer layer to obtain multi-component oxide thin films. The YBCO thin films were obtained by co-evaporation deposition of yttrium, copper and barium fluoride. Molecular beam epitaxy co-evaporation was adopted, and the evaporation source was controlled by a film thickness gauge to ensure that Y, Ba and Cu were completely oxidized instantly upon reaching the surface, avoiding oxygen-deficient phases and solving the problem of difficult large-area uniform preparation of multi-component oxide thin films.

[0048] (2) The multi-element oxide film of the present invention, YBCO, has the characteristic of high uniformity. For films with a size of 8 inches or less, the film non-uniformity is ≤3%.

[0049] (3) The application of a multi-element oxide thin film of the present invention is applied to the preparation of semiconductor devices or high-performance energy storage materials. It directly serves as a functional layer in extreme processes that require zero resistance, high current carrying capacity and high oxygen migration. It is deeply embedded in the three major industrial chains of electronic information, energy, catalysis and protection, forming a common technology platform for collaborative innovation of "materials-processes-devices". Attached Figure Description

[0050] Figure 1 This is a graph showing the non-uniformity test results of the 8-inch thin film prepared in Example 1;

[0051] Figure 2 for Figure 1 The AFM thickness test image at point #1 in the 8-inch thin film inhomogeneity test; among them, Figure 2 a is a non-contact scan image. Figure 2 b is the height distribution histogram;

[0052] Figure 3 for Figure 1 The AFM thickness test image at point #1 in the 8-inch thin film inhomogeneity test; among them, Figure 3 a is a single-line height profile. Figure 3 b is the power spectrum. Figure 3 c represents a single-line height histogram;

[0053] Figure 4 for Figure 1 Statistical results of surface morphology test at point #1 in the 8-inch thin film inhomogeneity test;

[0054] Figure 5This is a graph showing the actual parameters during the process of controlling the co-evaporation of YBCO thin film using a film thickness gauge in Example 1;

[0055] Figure 6 This is a graph showing the actual parameters at the end of the co-evaporation of the YBCO thin film controlled by the film thickness gauge in Example 1;

[0056] Figure 7 The image shows the non-uniformity test results of the 8-inch film prepared in Example 2.

[0057] Figure 8 The image shows the non-uniformity test results of the 8-inch thin film prepared in Example 3.

[0058] Figure 9 The image shows the non-uniformity test results of the 8-inch thin film prepared in Example 4.

[0059] Figure 10 The image shows the non-uniformity test results of the 8-inch film prepared in Example 5.

[0060] Figure 11 The image shows the non-uniformity test results of the 8-inch thin film prepared for Comparative Example 1.

[0061] Figure 12 The image shows the non-uniformity test results of the 8-inch thin film prepared for Comparative Example 2. Detailed Implementation

[0062] To further understand the content of the present invention, the present invention will be described in detail with reference to the embodiments.

[0063] The present application will be further described below with reference to specific embodiments.

[0064] It should be noted that terms such as "upper", "lower", "left", "right", and "middle" used in this specification are only for clarity of description and are not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of this application.

[0065] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0066] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable.

[0067] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as "less than about 4.5," which should be interpreted to include all the values ​​and ranges described above. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0068] Example 1

[0069] This embodiment describes a method for preparing a multi-element oxide thin film using a multi-source thermal resistance evaporation device and molecular beam epitaxy co-evaporation, comprising the following steps:

[0070] S1. Using a wafer as a substrate, the substrate is placed on the sample disk in the molecular beam epitaxy co-evaporation preparation chamber to ensure that the substrate is stable and accurately positioned in subsequent processes.

[0071] S2, Place the thermal evaporation material

[0072] This step involves placing the appropriate evaporation material and crucible in the thermal resistance evaporation source.

[0073] Yttrium (Y) material is placed in an Al2O3 crucible, and then the crucible is placed in a high-temperature evaporation source, namely the Y evaporation source, which is controlled by the first probe of the film thickness gauge.

[0074] The copper (Cu) material is placed in an Al2O3 crucible, and then the crucible is placed in a medium-temperature evaporation source, namely the Cu evaporation source, which is controlled by the second probe of the film thickness gauge.

[0075] Barium fluoride (BaF2) is placed in crucible W, and then crucible is placed in high-temperature evaporation source, namely Ba evaporation source, controlled by the third probe of film thickness gauge;

[0076] The silver (Ag) material was placed in an Al2O3 crucible, and then the crucible was placed in a medium-temperature evaporation source, namely the Ag evaporation source, which was controlled by the fourth probe of the film thickness gauge.

[0077] Yttrium-stabilized zirconia (YSZ) was placed in a Cu crucible, and then the crucible was placed in an electron gun pot, which was designated as electron gun pot 1 and controlled by the fifth probe of the film thickness gauge.

[0078] Cerium oxide (CeO2) is placed in a Cu crucible, which is then placed in an electron gun pot, designated as electron gun pot 2, and controlled by the fifth probe of the film thickness gauge.

[0079] S3. Evacuate the cavity containing the substrate to the preset vacuum level to provide a vacuum environment for subsequent thin film fabrication processes. The cavity vacuum level is 9 × 10⁻⁶. -8 mbar.

[0080] Test the working status of the film thickness gauge probe before evacuating the cavity to avoid having to readjust the vacuum due to probe failure after evacuation.

[0081] S3 and YSZ buffer layer deposition

[0082] A YSZ buffer layer was deposited on the substrate in a molecular beam epitaxy co-evaporation preparation cavity.

[0083] The substrate is heated by an upper heating plate and a lower heating plate, both of which are 100 ℃ at a rate of 30 ℃ / min, i.e., the deposition temperature is 100 ℃.

[0084] Pure oxygen was maintained during the deposition process, with an O2 flow rate of 5 sccm and a sample disk rotation speed of 2 r / s.

[0085] The evaporation rate of YSZ was set to 0.5 Å / s and the thickness to 200 nm at the fifth probe position of the film thickness gauge. The PID parameters were: proportional P = 30, integral I = 4, and derivative D = 1. The electron beam was controlled by the film thickness gauge to carry out automatic evaporation.

[0086] After electron beam evaporation deposition, the flow rate of O2 was maintained at 5 sccm and the rotation speed of the sample disk was maintained at 2 r / s for annealing. The temperature of both the upper and lower heating disks was 700 ℃, that is, the annealing temperature was 700 ℃ and the annealing time was 2 h, to obtain a substrate containing a YSZ buffer layer.

[0087] S4, CeO2 buffer layer deposition

[0088] CeO2 buffer layer deposition was performed on a substrate containing a YSZ buffer layer;

[0089] The substrate is heated by an upper heating plate and a lower heating plate, both of which are 80 ℃ at a rate of 50 ℃ / min, i.e., the deposition temperature is 80 ℃.

[0090] Pure oxygen was maintained during the deposition process, with an O2 flow rate of 5 sccm and a sample disk rotation speed of 2 r / s.

[0091] The evaporation rate of CeO2 was set to 3 Å / s and the thickness to 40 nm at the fifth probe position of the film thickness gauge. The PID parameters were: proportional P = 30, integral I = 4, and derivative D = 1. The electron beam was controlled by the film thickness gauge to carry out automatic evaporation.

[0092] After electron beam evaporation deposition, annealing was performed, with the flow rate of the O2 flow meter maintained at 5 sccm, the rotation speed of the sample disk maintained at 2 r / s, and the temperature of both the upper and lower heating disks maintained at 800 ℃, i.e., the annealing temperature was 700 ℃, and the annealing time was 2 h, to obtain a substrate containing a YSZ buffer layer and a CeO2 buffer layer.

[0093] Steps S3 and S4 are used to prepare a buffer layer between the substrate and the YBCO thin film. Its main functions are to reduce lattice mismatch, suppress interfacial reactions, and guide epitaxial growth.

[0094] S5 and YBCO layer deposition

[0095] YBCO thin films were prepared using a co-evaporation method. YBCO thin films were deposited on a substrate containing a YSZ buffer layer and a CeO2 buffer layer. The YBCO thin films were obtained by co-evaporation deposition of yttrium, copper and barium fluoride.

[0096] The substrate is heated by an upper heating plate and a lower heating plate, both of which are 850 ℃ at a rate of 50 ℃ / min, i.e., the co-evaporation deposition temperature is 850 ℃.

[0097] During the deposition process, ozone was maintained, with 12% O3 and 82% O2 by mass, i.e., the flow rate of 12% O3 / O2 was 5 sccm, and the rotation speed of the sample disk was 2 r / s.

[0098] At the first probe position of the film thickness gauge, the evaporation rate of the Y evaporation source was set to 0.3 Å / s, the thickness to 94 nm, and the PID parameters were: proportional P = 30, integral I = 4, and derivative D = 1.

[0099] At the second probe position of the film thickness gauge, the evaporation rate of the Cu evaporation source was set to 0.5 Å / s, the thickness to 156 nm, and the PID parameters were: proportional P = 30, integral I = 4, and derivative D = 1.

[0100] The evaporation rate of the Ba evaporation source was set to 0.8 Å / s at the third probe position of the film thickness gauge, and the thickness was set to 250 nm. The PID parameters were: proportional P = 30, integral I = 4, and derivative D = 1. The Y, Cu, and Ba evaporation sources were controlled by the film thickness gauge to co-evaporate, and the three evaporation sources were controlled to heat up synchronously. The total co-evaporation thickness was 500 nm.

[0101] After the co-evaporation deposition of the evaporation source is completed, 12% O3 / O2 is continuously introduced at a flow rate of 10 sccm, and the sample is rotated at 2 r / s. High-temperature annealing is performed first, with the temperature of both the upper and lower heating plates set to 900 ℃, i.e., the high-temperature annealing temperature is 900 ℃ and the high-temperature annealing time is 4 h. Then, low-temperature annealing is performed, with the temperature of both the upper and lower heating plates set to 500 ℃, i.e., the low-temperature annealing temperature is 500 ℃ and the low-temperature annealing time is 1 h, to obtain YBCO thin film, i.e., multi-component oxide thin film.

[0102] S6, Contact electrode deposition

[0103] The preparation of contact electrodes for YBCO thin films involves depositing contact electrodes on YBCO thin films. These electrodes are mainly used to connect external circuits and inject / extract superconducting current. The materials must meet the requirements of low contact resistance, high chemical stability, and thermal expansion matching. Ag has high properties, so an evaporation source is used to evaporate Ag electrodes.

[0104] Pure oxygen was maintained during the deposition process, with an O2 flow rate of 2 sccm and a sample disk rotation speed of 2 r / s.

[0105] Two evaporation deposition processes were performed. In the first evaporation deposition, the Ag evaporation source was set at an evaporation rate of 0.1 Å / s at the fourth probe position of the thickness gauge, achieving a thickness of 30 nm. The PID parameters were: proportional P = 30, integral I = 4, and derivative D = 1. The Ag evaporation source was controlled by the thickness gauge for evaporation. After reaching the desired thickness, a second evaporation deposition was performed. The Ag evaporation source was set at an evaporation rate of 0.5 Å / s at the fourth probe position of the thickness gauge, achieving a thickness of 70 nm. The PID parameters were: proportional P = 30, integral I = 4, and derivative D = 1. The Ag evaporation source was controlled by the thickness gauge for evaporation.

[0106] After evaporation by the Ag evaporation source, annealing was performed while maintaining the oxygen flow rate and sample disk rotation speed. The temperature of both the upper and lower heating disks was 550 °C, and the rate was 50 °C / min, i.e., the annealing temperature was 550 °C and the annealing time was 0.5 h, resulting in a multi-element oxide film containing a contact electrode.

[0107] Note 1: When using a film thickness gauge to control the electron beam and evaporation source for evaporation, the corresponding film thickness gauge probe must first be calibrated to ensure that the rate monitored at the probe and the deposition rate at the sample plate are basically consistent.

[0108] Note 2: During the evaporation process controlled by the film thickness gauge, if the set film thickness is reached, the film thickness gauge will stop evaporation control. Therefore, the following protection is written in the PC program control: if the thickness is reached before the evaporation rate is reached, the film thickness will be automatically zeroed in advance, and the film thickness gauge will not stop evaporation control.

[0109] Method for testing the inhomogeneity of multi-component oxide thin films: The inhomogeneity of multi-component oxide thin films was determined using atomic force microscopy (AFM). Nine different locations were selected for scanning on the surface of an 8-inch multi-component oxide thin film, and five different locations were selected for scanning on the surface of a 4-inch multi-component oxide thin film. The formula for calculating the inhomogeneity of the film is as follows:

[0110]

[0111] In the formula: the maximum value is the maximum film thickness, the minimum value is the minimum film thickness, and the average value is the average film thickness.

[0112] The non-uniformity data of the 8-inch multi-component oxide thin film prepared by the method of this embodiment are as follows: Figure 1 As shown, substituting into the formula for calculating film non-uniformity, the non-uniformity of 8 inches is found to be 1.143%.

[0113] Figures 2-4 for Figure 1 AFM thickness test plot at point #1 in the 8-inch film non-uniformity test. Figure 2 A non-contact scanning image shows the thin film on the left and the substrate on the right. Figure 2 b. The height distribution histogram shows that the overall undulation of the membrane surface is gentle. Figure 3 The single-line height profile shows that the height at this point is 85.222 nm lower than the reference plane; this value represents the film thickness. Figure 3 The power spectrum (b) shows that the film surface has no obvious roughness and good smoothness. Figure 3 The single-line height histogram further confirms that the surface undulations at this location are gentle, with no obvious abnormal protrusions or deep pits. Figure 4 The surface morphology statistics show that the median is 49.113 nm and the mean is 44.811 nm, which are close to each other, indicating a symmetrical height distribution. The roughness index is 42.596 nm (root mean square roughness) and 42.347 nm (arithmetic mean roughness), which are close to each other, further verifying the symmetrical distribution. The shape parameters are skewness of -0.081 and kurtosis of 1.028, both close to a normal distribution, indicating that the surface undulations are "normal" with varying heights and no sharp peaks or deep pits.

[0114] exist Figure 1 From the 9-point film thickness data of the 8-inch film, points #1-#5 can be taken to obtain the non-uniformity data of the 4-inch multi-element oxide film. Substituting into the film non-uniformity calculation formula, the non-uniformity of the 4-inch film is 0.947%.

[0115] Therefore, the multi-element oxide film prepared in this embodiment achieves highly uniform thickness deposition across the entire 8-inch wafer, meeting the stringent requirements for thickness consistency in large-area, thick-film applications.

[0116] In this embodiment, a film thickness gauge was used to control the evaporation rates of Y (0.3 Å / s), Cu (0.5 Å / s), and Ba (0.8 Å / s) during the co-evaporation deposition process. Figure 5 and Figure 6 As shown, the set values ​​of the evaporation rates of each element are highly consistent with the real-time monitoring values, indicating that the three elements Y, Ba and Cu are co-deposited strictly according to the set evaporation rates during the co-evaporation process, resulting in a YBCO thin film with high thickness uniformity.

[0117] Example 2

[0118] This embodiment describes a method for preparing a multi-element oxide thin film using a multi-source thermal resistance evaporation device and molecular beam epitaxy co-evaporation. It is essentially the same as in Embodiment 1, except that:

[0119] The PID parameters in steps S3 to S6 are: proportional P = 50, integral I = 16, and derivative D = 4.

[0120] The non-uniformity data measured in this embodiment of the multi-element oxide thin film are as follows: Figure 7 As shown, substituting the data into the film non-uniformity calculation formula, the non-uniformity of the 8-inch film in this embodiment is 2.018%.

[0121] In this embodiment, adjusting the PID parameters of the film thickness gauge can change the time and stability required for the evaporation to reach the set rate. Compared to Embodiment 1, the PID parameters in this embodiment are replaced with 50, 16, 4 instead of 30, 4, 1. A larger P value allows the film thickness gauge to control the evaporation source and electron gun to reach the set rate faster. Larger I and D values ​​increase control sensitivity, compensating for overshoot caused by excessively fast evaporation and ultimately stabilizing the evaporation rate at the set rate. Due to the higher sensitivity of the modified PID, the co-evaporation process exhibits brief fluctuations in the evaporation rate, resulting in slightly higher stability and film non-uniformity compared to Embodiment 1.

[0122] Example 3

[0123] This embodiment describes a method for preparing a multi-element oxide thin film using a multi-source thermal resistance evaporation device and molecular beam epitaxy co-evaporation. It is essentially the same as in Embodiment 1, except that:

[0124] The sample disk rotation speed in steps S3 to S6 is 5 r / s.

[0125] The non-uniformity data measured in this embodiment of the multi-element oxide thin film are as follows: Figure 8 As shown, substituting the data into the film non-uniformity calculation formula, the non-uniformity of the 8-inch film in this embodiment is 1.56%.

[0126] In this embodiment, the switching frequency between thin film deposition and thin film oxidation can be changed by adjusting the sample disk rotation speed, thereby altering the uniformity and crystallinity of the oxide thin film formation. Compared to Example 1, this embodiment has a higher sample disk rotation speed, resulting in a higher switching frequency between the thin film deposition and thin film oxidation processes of the multi-element oxide thin film. This allows the thin film to be rapidly oxidized when deposited on the wafer surface. However, due to the shorter residence time of metal atoms and reactive gases on the substrate surface, the thin film prepared in this embodiment exhibits slightly higher non-uniformity compared to Example 1.

[0127] Example 4

[0128] This embodiment describes a method for preparing a multi-element oxide thin film using a multi-source thermal resistance evaporation device and molecular beam epitaxy co-evaporation. It is essentially the same as in Embodiment 1, except that:

[0129] The sample disk rotation speed in steps S3 to S6 is 3 r / s.

[0130] The non-uniformity data measured in this embodiment of the multi-element oxide thin film are as follows: Figure 9 As shown, substituting the data into the film non-uniformity calculation formula, the non-uniformity of the 8-inch film in this embodiment is found to be 0.926%.

[0131] In this embodiment, adjusting the sample stage rotation speed can change the switching frequency between thin film deposition and thin film oxidation, thereby altering the uniformity and crystallinity of the oxide thin film formation. The sample stage rotation speed in this embodiment is set to 3 r / s, falling between 5 r / s and 2 r / s, to explore the effect of different sample stage rotation speeds on thin film inhomogeneity. Compared to sample stage rotation speeds of 2 r / s and 5 r / s, the thin film obtained at a sample stage rotation speed of 3 r / s exhibits lower inhomogeneity, indicating that this rotation speed has the best effect on the reaction of metal atoms and reactive gases.

[0132] Example 5

[0133] This embodiment describes a method for preparing a multi-element oxide thin film using a multi-source thermal resistance evaporation device and molecular beam epitaxy co-evaporation. It is essentially the same as in Embodiment 1, except that:

[0134] The sample disk rotation speed in steps S3 to S6 is 0.5 r / s.

[0135] The non-uniformity data measured in this embodiment of the multi-element oxide thin film are as follows: Figure 10 As shown, substituting the data into the film non-uniformity calculation formula, the non-uniformity of the 8-inch film prepared in this embodiment is 2.64%.

[0136] In this embodiment, the switching frequency between film deposition and film oxidation can be changed by adjusting the sample disk rotation speed, thereby altering the uniformity and crystallinity of the oxide film formation. The sample disk rotation speed was set to 0.5 r / s to explore the effect of different sample stage rotation speeds on film inhomogeneity. Therefore, compared to Example 1, the film prepared in this embodiment has higher inhomogeneity. This shows that at low rotation speeds, the grain growth time varies slightly at different locations on the substrate, resulting in slight differences in film thickness at different locations and slightly higher film inhomogeneity.

[0137] Comparative Example 1

[0138] The preparation method of this comparative example of a multi-element oxide thin film is basically the same as that in Example 1, using a multi-source thermal resistance evaporation device and molecular beam epitaxy co-evaporation. The difference is that:

[0139] The sample disk rotation speed in steps S3 to S6 is 0.1 r / s.

[0140] The non-uniformity data measured for the multi-component oxide thin films prepared in this comparative example are as follows: Figure 11 As shown, substituting the data into the film non-uniformity calculation formula, the non-uniformity of the 8-inch film prepared in this comparative example is found to be 3.58%.

[0141] In this comparative example, the switching frequency between film deposition and film oxidation can be changed by adjusting the sample stage rotation speed, thereby altering the uniformity and crystallinity of the oxide film formation. Compared to Examples 1-5, the sample stage rotation speed in this comparative example is set to 0.1 r / s. Because the sample stage rotation speed is too low, the growth rate difference from the center to the edge is large, resulting in greater inhomogeneity. Therefore, the film prepared in this comparative example has higher inhomogeneity.

[0142] Comparative Example 2

[0143] The preparation method of this comparative example of a multi-element oxide thin film is basically the same as that in Example 1, using a multi-source thermal resistance evaporation device and molecular beam epitaxy co-evaporation. The difference is that:

[0144] The PID parameters in steps S3 to S6 are: proportional P = 100, integral I = 20, and derivative D = 5.

[0145] The non-uniformity data measured for the multi-component oxide thin films prepared in this comparative example are as follows: Figure 12 As shown, substituting the data into the film non-uniformity calculation formula, the non-uniformity of the 8-inch film is found to be 5.49%.

[0146] In this comparative example, adjusting the PID parameters of the film thickness gauge can change the time and stability required for the evaporation to reach the set rate. Compared to Examples 1-5, the PID parameters in this comparative example are: proportional P = 100, integral I = 20, and derivative D = 5. The aim is to explore the evaporation effect at a higher heating rate, and with higher I and D values, the evaporation rate can be stabilized at the set rate more quickly. However, due to the excessively fast heating rate, multiple fluctuations occurred before the evaporation rate reached the set rate, and rate fluctuations still existed after the rate reached the set rate, resulting in higher film non-uniformity.

[0147] In summary, the thickness non-uniformity of the multi-component oxide films prepared in Examples 1-5 is ≤3%, which effectively suppresses the performance dispersion problem caused by macroscopic defects and microscopic composition fluctuations, thereby significantly improving the overall yield of the products and ensuring a high degree of consistency in the performance of batch products.

[0148] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications, improvements, and substitutions without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing a multi-component oxide thin film, characterized in that: Prepared by molecular beam epitaxy co-evaporation, including the following steps: The substrate was placed in a molecular beam epitaxy co-evaporation preparation cavity, and the cavity was evacuated to a vacuum level of 1×10⁻⁶. -8 mbar~9×10 -8 mbar; The substrate is placed on a sample disk in the molecular beam epitaxy co-evaporation preparation chamber, and the rotation speed of the sample disk is 1 r / s to 5 r / s; In the molecular beam epitaxial co-evaporation preparation chamber, YSZ buffer layer and CeO2 buffer layer are deposited sequentially from bottom to top on the substrate. Electron beam automatic evaporation is controlled by a film thickness gauge to obtain a substrate containing buffer layers. Yttrium, copper and barium fluoride were co-evaporated on the substrate containing the buffer layer to deposit a YBCO thin film. The co-evaporation deposition was carried out by controlling the Y evaporation source, Cu evaporation source and Ba evaporation source with a film thickness gauge to obtain the multi-component oxide thin film. The deposition temperatures for the YSZ buffer layer and the CeO2 buffer layer are 80 ℃ to 100 ℃, and the deposition temperature for the YBCO thin film is 850 ℃ to 950 ℃; the evaporation rates for the YSZ buffer layer and the CeO2 buffer layer are 3 Å / s to 5 Å / s, and the evaporation rate for the co-evaporation deposition is 0.3 Å / s to 0.8 Å / s; The PID parameters for the YSZ buffer layer deposition and the CeO2 buffer layer deposition are: proportional P = 30~50, integral I = 4~16, and derivative D = 1~4. The PID parameters for the co-evaporation deposition are: proportional P = 30-50, integral I = 4-16, and derivative D = 1-4.

2. The method for preparing a multi-component oxide thin film according to claim 1, characterized in that: The thickness of the YSZ buffer layer is 100 nm to 200 nm; the thickness of the CeO2 buffer layer is 10 nm to 40 nm.

3. The method for preparing a multi-component oxide thin film according to claim 2, characterized in that: The annealing temperature after deposition of the YSZ buffer layer is 700 ℃~800 ℃, and the time is 1 h~2 h; the annealing temperature after deposition of the CeO2 buffer layer is 700 ℃~800 ℃, and the time is 1 h~2 h.

4. The method for preparing a multi-component oxide thin film according to claim 1, characterized in that: The thickness of the YBCO thin film is 500 nm to 600 nm.

5. The method for preparing a multi-component oxide thin film according to claim 4, characterized in that: After co-evaporation deposition, the material is first subjected to high-temperature annealing at a temperature of 900 ℃ to 1000 ℃ for 4 h to 5 h; then it is subjected to low-temperature annealing at a temperature of 400 ℃ to 500 ℃ for 1 h to 2 h.

6. A method for preparing a multi-component oxide thin film according to any one of claims 1-5, characterized in that: It also includes the deposition of contact electrodes on YBCO thin films.

7. The application of the method for preparing a multi-component oxide thin film according to any one of claims 1-6, characterized in that: The method for preparing the multi-component oxide thin film can be applied to the preparation of semiconductor devices or high-performance energy storage materials.

Images