Method for growing diamond by ion implantation of carbon on iridium-containing substrate

Abstract

According to the method for growing the diamond through ion implantation of carbon on the iridium-containing substrate, an ion implantation device comprises an iridium-containing base substrate and a target material, gas and an ion source are provided for a reaction cavity, a diamond core is formed on the base substrate through an ion implantation method, the base substrate is transferred into an MPCVD device, and diamond growth is conducted through the MPCVD device. The technical problem that the nucleation density of the large-size diamond containing the Ir substrate is not uniform is solved, and the technical effect of improving the growth quality of the large-size diamond containing the Ir substrate is achieved. The method is an innovative method combining multi-energy ion implantation and an MPCVD process, a nucleation layer in gradient distribution is formed in an iridium-containing substrate by accurately regulating and controlling carbon ion implantation energy and dosage, and meanwhile, process parameters in a growth stage are optimized, so that the bottleneck in the prior art is broken through, and efficient preparation of a high-quality diamond film is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of diamond heteroepitaxial growth, and particularly relates to a method for growing diamond by ion implantation of carbon on an iridium-containing substrate. Background Art

[0002] Due to its physical and chemical properties such as ultra-high hardness, high thermal conductivity, wide bandgap semiconductor characteristics, and excellent biocompatibility, diamond has important applications in fields such as precision machining, electronic devices, optical windows, and biomedicine. However, natural diamonds are scarce and costly, so the preparation of high-quality artificial diamonds by chemical vapor deposition (CVD) technology has become a research hotspot. Among them, heteroepitaxial growth of diamond thin films requires a lattice-matched substrate material to reduce the density of interface defects. Iridium (Ir) has become one of the ideal substrate materials because of its high lattice compatibility with diamond.

[0003] Currently, diamond growth processes based on iridium substrates usually require pre-nucleation treatments such as mechanical grinding, ultrasonic nano-diamond dispersion, or bias-enhanced nucleation methods to increase the nucleation density. However, these methods have significant limitations: mechanical or chemical pretreatment is likely to damage the substrate surface, resulting in an increase in defects and affecting the uniformity and crystallization quality of the epitaxial diamond film; although the bias-enhanced nucleation method (BEN) can increase the nucleation density, it is extremely sensitive to equipment parameters (such as bias voltage, temperature, gas ratio), has a narrow process window, and poor repeatability; if a single energy is used for ion implantation in the traditional ion implantation method, the distribution depth of carbon ions is concentrated, and it is difficult to form a gradient concentration, resulting in an uneven nucleation layer and easy stress accumulation and interface peeling during the subsequent growth process.

[0004] In addition, microwave plasma chemical vapor deposition (MPCVD) is mostly used for diamond growth in the prior art. However, if the quality of the nucleation layer is poor (such as low density or uneven distribution), amorphous carbon or graphite phase impurities are likely to appear during the growth stage, reducing the performance of the diamond film. Therefore, how to achieve a high-density, uniformly controllable nucleation layer without damaging the substrate and optimize the growth process parameters to improve the quality of diamond remains a technical problem to be solved urgently. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a method for growing diamond by carbon ion implantation, aiming to solve the problems of poor quality of the nucleation layer and poor controllability of carbon ion implantation energy and dose.

[0006] To achieve the above object, a method for growing diamond by carbon ion implantation provided by the present invention includes the following steps:

[0007] Nucleation process:

[0008] (a) Provide an iridium-based substrate and a graphite target;

[0009] (b) Inject carbon ions onto the surface of the iridium-containing base substrate by ion implantation to form diamond nuclei.

[0010] Growth process:

[0011] (c) Transfer the nucleated iridium-containing base substrate to an MPCVD device, introduce process gases, heat it, and grow diamond.

[0012] Preferably, the target is a graphite target with a purity greater than 99.9%.

[0013] Preferably, the iridium-containing base substrate includes a single crystal or composite substrate of A-plane sapphire / Ir substrate, YSZ / Ir substrate, SrTiO3 / Ir substrate, or a combination thereof.

[0014] Preferably, the ion implantation method in step (b) includes:

[0015] (b1) Evacuate the reaction chamber of the ion implantation equipment to a preset pressure.

[0016] (b2) Introduce argon gas into the reaction chamber and start the ion source.

[0017] (b3) Clean the surface of the iridium-containing base substrate with argon ions of low energy and large beam current.

[0018] (b4) Start a multi-energy superposition injection program, inject carbon ions in turn from high to low according to four energies, the incident angle of ion injection is perpendicular to the substrate surface, so that carbon ions are injected into the Ir film, and the total injection dose is ;

[0019] (b5) After closing the ion source, introduce inert gas into the reaction chamber to normal pressure.

[0020] (b6) Take out the substrate and perform wet cleaning on it to remove surface contamination.

[0021] Preferably, in step (b5), the nitrogen gas introduction rate is 5-10 L / min, and the recovery time is 5-10 minutes.

[0022] Preferably, the time for cleaning the surface of the iridium-containing base substrate is 2-10 min.

[0023] Preferably, the four energies are 50 keV, 45 keV, 40 keV, and 30 keV.

[0024] Preferably, introducing inert gas into the reaction chamber to normal pressure includes slowly introducing nitrogen gas into the chamber to make the internal pressure of the chamber reach normal pressure.

[0025] Preferably, in the step (c), the process gas is a mixed gas of methane and hydrogen, and the volume ratio of methane is 7%.

[0026] Preferably, in the step (c), the heating temperature is 800 - 1000 °C, the reaction chamber pressure is 20 - 30 Torr, and the growth time is 10 - 48 hours.

[0027] 10. The method according to claim 1, wherein after the step (c) is completed, it further includes: stopping the supply of the process gas and cooling to room temperature at a rate of 5 - 10 °C / min.

[0028] A method for growing diamond by ion implantation of carbon on an iridium-containing substrate provided by the present invention. The ion implantation equipment device includes an iridium-containing base substrate and a target. Gas and an ion source are provided to the reaction chamber. Diamond nuclei are formed on the base substrate by ion implantation method. The base substrate is transferred to an MPCVD equipment, and diamond growth is carried out by the MPCVD equipment. This solves the technical problem of uneven nucleation density of diamond nuclei on a large-size Ir-containing substrate, and achieves the technical effect of improving the quality of diamond growth on a large-size Ir-containing substrate. This method combines an innovative method of multi-energy ion implantation and MPCVD process. By precisely controlling the carbon ion implantation energy and dose, a gradient-distributed nucleation layer is formed in the iridium-containing substrate, and at the same time, the process parameters in the growth stage are optimized to break through the bottleneck of the existing technology and realize the efficient preparation of high-quality diamond thin films. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. At the same time, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0030] Figure 1 It is a flowchart of growing diamond by ion implantation of carbon on an iridium-containing substrate provided by the present invention;

[0031] Figure 2 It is a flowchart of forming diamond nuclei by ion implantation method provided by the present invention;

[0032] Figure 3 It is another flowchart of forming diamond nuclei by ion implantation method provided by the present invention. Detailed Embodiments

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] like Figure 1 As shown, the flow chart of growing diamond by ion implantation of carbon on an iridium-containing substrate provided in this embodiment includes a nucleation process: (a) providing an iridium-containing base substrate and a graphite target with a purity greater than 99.9%; (b) injecting carbon ions into the surface of the iridium-containing base substrate by ion implantation to form diamond nuclei; and a growth process: (c) transferring the iridium-containing base substrate after nucleation to an MPCVD device, introducing process gas, heating and performing diamond growth.

[0036] In the nucleation process, the base substrate needs to be cleaned in step (a), and the A-side sapphire substrate / Ir substrate is cleaned with acetone, ethanol, and ultrapure water solution in sequence, and then blown dry with nitrogen. In other embodiments, the iridium-containing base substrate can also be a single crystal or composite substrate of a YSZ / Ir substrate, a SrTiO3 / Ir substrate, or a combination thereof.

[0037] In the nucleation process, Figure 2 As shown, the specific process of step (b) is to place the cleaned iridium-containing base substrate and the graphite target with a purity greater than 99.9% into the ion implantation equipment, and (b1) evacuate the ion implantation equipment to a vacuum degree of 7×10 -3 Pa or less. (b2) Inert gas such as argon is delivered into the equipment to ensure that the vacuum is maintained stable and to reduce the interference of oxygen and impurities. (b3) Before carbon is injected, the surface of the base substrate is cleaned with low-energy, large-beam argon ions for 2-10 minutes, preferably 5 minutes. (b4) The ion source voltage is turned on, and the incident angle of ion injection is perpendicular to the substrate surface, so that carbon ions are injected into the Ir film, including multi-energy superposition injection, and the four energies of 50, 45, 40, and 30 keV are injected into the sample surface from high to low, and the total injection dose is In other examples, the implantation method may be single energy implantation. (b5) After the implantation is completed, the gas inlet valve and the ion source are closed, the operation is stopped, and nitrogen is supplied to the device to slowly return the device to normal pressure. (b6) The substrate is then removed for wet cleaning to remove surface contamination. The above process obtains uniformly nucleated and high-density diamond nuclei, which is conducive to subsequent diamond growth.

[0038] In the nucleation process, the incident angle of ion implantation is perpendicular to the substrate surface, which can maximize the collision scattering of carbon ions with the iridium crystal lattice, avoid the long-distance penetration of ions along the lattice channels, ensure that the implanted ions stay in the target area of the shallow surface layer, and improve the nucleation positioning accuracy. Vertical implantation generates uniform lattice damage near the surface of the iridium film, providing high-density and uniformly distributed defect sites for diamond nucleation and promoting the uniform nucleation of diamond nuclei.

[0039] In the nucleation process, the multi-energy superposition implantation method is adopted for carbon ion implantation into the Ir film. Four energy levels of 50, 45, 40, and 30 keV are used for implantation, which can cover different projection ranges. The high-energy ions of 50 keV penetrate deeper to form deep nucleation points, and the low-energy ions of 30 keV are concentrated in the shallow surface layer. The multi-energy superposition can achieve a continuous and uniform distribution of carbon ions in the depth direction, avoiding local concentration peaks caused by a single energy.

[0040] In the nucleation process, the vertical implantation and multi-energy superposition implantation methods are adopted to overcome the limitations of single conditions, form a three-dimensional uniform carbon supersaturated layer on the surface layer of the iridium film, significantly improve the diamond nucleation density, enhance the diamond / iridium interface bonding strength, and reduce the risk of thermal stress cracking.

[0041] In the growth process, in step (c), the substrate with successful nucleation is transferred to the MPCVD equipment. Specifically, the target substrate is placed on the molybdenum tray in the MPCVD equipment. The molybdenum tray is driven to rotate, and the rotation speed of the substrate can be adjusted by adjusting the rotation speed of the molybdenum tray. Before or after heating the target substrate, the molybdenum tray drives the target substrate to rotate at a speed of 3 rpm.

[0042] Then, the reaction chamber is evacuated, process gas is introduced, and single-crystal diamond is grown by heating. Specifically, the reaction chamber is evacuated to remove air and other impurities in the chamber, providing a clean environment for subsequent chemical reactions. Process gas composed of methane and hydrogen is introduced into the reaction chamber. In this embodiment, the proportion of methane is 7%. To ensure the stability of the flow rate and pressure of the process gas and maintain the gas concentration and reaction rate in the reaction chamber, the air pressure is controlled at 1×10 5 Pa. The microwave power and pressure are turned on, and the target substrate is heated to 800 - 1000 °C, preferably heated to 900 °C to ensure that the surface of the iridium film reaches an appropriate reaction temperature, which is beneficial to the growth of diamond. The pressure is 150 mbar, the power is 6000 W, and the growth time is 10 - 48 h. After the reaction is completed, the heating source is turned off, the process gas is stopped from being introduced, and it is cooled to room temperature at a rate of 5 - 10 °C / min. After the reaction chamber is naturally cooled to room temperature, the substrate is taken out.

[0043] Example 2

[0044] In order to further reduce the stress and defects during the diamond nucleation process, improve the quality and uniformity of nucleation, and enable the subsequent growth of dense and uniform single-crystal diamond, in the embodiments of the present application, the nucleation process (b) is further expanded and optimized on the basis of the above embodiments, as Figure 3 shown, specifically as follows:

[0045] Put the iridium-containing base substrate after cleaning treatment and a graphite target with a purity greater than 99.9% into the ion implantation equipment. (c1) Evacuate the ion implantation equipment until the vacuum degree reaches below 7×10 -3 Pa. (c2) Deliver an inert gas such as argon into the equipment to ensure the stability of the vacuum and reduce the interference of oxygen and impurities. (c3) Before injecting carbon, clean the surface of the base substrate with low-energy and large-beam argon ions for 2-10 min, preferably 5 min. (c4) Turn on the ion source voltage. The incident angle of ion injection is inclined 5-15° perpendicular to the substrate surface, and the preferred incident angle is 8°. The carbon ions are injected into the Ir film, including multi-energy superposition injection. First, inject the sample surface in sequence from high to low according to two energies of 50 and 45 keV, and the injection time is 2-5 min, preferably 5 min. Then turn on the bias power supply, set the voltage to -100V, and at the same time inject carbon ions in sequence from high to low according to two energies of 30 and 25 keV, and the injection time is 5-10 min, preferably the injection time is 5 min. The addition of bias can form finer and more uniform diamond nuclei. In other examples, the injection method can be single-energy injection, and the timing of adding bias can be changed, for example, applying bias from the beginning. (c5) After the injection is completed, close the gas inlet valve, the ion source and the bias, stop the operation, and deliver nitrogen into the device to slowly return the equipment to normal pressure. (c6) Subsequently, take out the substrate and perform wet cleaning to remove surface contamination. Through the above process, diamond nuclei with uniform nucleation and high density are obtained, which is beneficial to the subsequent growth of diamond.

[0046] In the step c4, the incident angle of ion injection is preferably 8°. The 8° inclination angle achieves a good balance between suppressing the channeling effect and maintaining the lateral injection uniformity, avoids the dose distribution shift caused by large-angle inclination, and can improve the process repeatability.

[0047] In step c4, a dual-energy time-sharing injection method is adopted, with the high-energy group injected first and the low-energy group injected subsequently. First, 5 min of injection is carried out at two energies of 50 and 45 keV, and then 5 min of injection is carried out at two energies of 30 and 25 keV. The priority injection of the high-energy group forms nucleation sites deep in the iridium film, and the subsequent injection of the low-energy group constructs a high-concentration carbon layer on the shallow surface layer, forming a continuous carbon concentration gradient from deep to shallow. This time-sharing operation of injecting for 5 min in the high-energy group and injecting for 5 min in the low-energy group reduces the single-injection heat load, avoids lattice recovery or carbon diffusion caused by overheating of the substrate due to continuous injection, ensures the stability of the damaged layer, allows the dynamic adjustment of the ion beam current intensity, precisely controls the dose distribution in different energy ranges, and reduces the aggregation of interface defects.

[0048] A method for ion implantation of carbon to grow diamond on an iridium-containing substrate provided by the present invention. The ion implantation equipment device includes an iridium-based substrate and a target. Gas and an ion source are provided to the reaction chamber, and diamond nuclei are formed on the base substrate by ion implantation. The base substrate is transferred to an MPCVD device, and diamond growth is carried out by the MPCVD device, solving the technical problem of uneven nucleation density of diamond nuclei on a large-sized Ir-containing substrate and achieving the technical effect of improving the quality of diamond growth on a large-sized Ir-containing substrate. This method combines an innovative method of multi-energy ion implantation and the MPCVD process. By precisely regulating the energy and dose of carbon ion implantation, a nucleation layer with a gradient distribution is formed in the iridium-containing substrate, and at the same time, the process parameters in the growth stage are optimized to break through the bottleneck of the existing technology and achieve the efficient preparation of high-quality diamond thin films.

[0049] It should be noted that the technical features in the above embodiments can be combined arbitrarily, and the combined technical solutions all fall within the protection scope of this application. And in this article, terms such as "including", "comprising" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including the said element.

[0050] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for growing diamond by ion implantation of carbon on an iridium-containing substrate, characterized in that, It includes the following steps: Nucleation process: (a)Provide an iridium-containing base substrate and a graphite target; (b)Inject carbon ions into the surface of the iridium-containing base substrate by ion implantation to form diamond nuclei; Growth process: (c)Transfer the nucleated iridium-containing base substrate to an MPCVD device, introduce process gases, heat it, and carry out diamond growth.

2. The method according to claim 1, characterized in that The target is a graphite target with a purity greater than 99.9%.

3. The method according to claim 1, wherein The iridium-containing base substrate includes a single-crystal or composite substrate of A-plane sapphire / Ir substrate, YSZ / Ir substrate, SrTiO3 / Ir substrate, or a combination thereof.

4. The method according to claim 1, characterized in that, The ion implantation method in the step (b) includes: (b1)Vacuum the reaction chamber of the ion implantation equipment to a preset pressure; (b2)Introduce argon into the reaction chamber and start the ion source; (b3)Clean the surface of the iridium-containing base substrate with low-energy and large-beam argon ions; (b4) Start the multi-energy superposition injection program, inject carbon ions in order from high to low according to four energies, and the incident angle of ion injection is perpendicular to the substrate surface, so that carbon ions are injected into the Ir film, and the total injection dose is ; (b5)After closing the ion source, introduce an inert gas into the reaction chamber to normal pressure; (b6)Take out the substrate and perform wet cleaning on it to remove surface contamination.

5. The method according to claim 4, wherein In the step (b5), the nitrogen gas introduction rate is 5-10 L / min, and the recovery time is 5-10 minutes.

6. The method according to claim 4, wherein The time for cleaning the surface of the iridium-containing base substrate is 2-10 min.

7. The method according to claim 4, characterized in that The four energies are 50 keV, 45 keV, 40 keV, and 30 keV.

8. The method according to claim 4, characterized in that, Introducing an inert gas into the reaction chamber to normal pressure includes slowly introducing nitrogen gas into the chamber to make the internal pressure of the chamber reach normal pressure.

9. The method according to claim 1, wherein In the step (c), the process gas is a mixed gas of methane and hydrogen, and the volume ratio of methane is 7%.

10. The method according to claim 1, characterized in that, In the step (c), the heating temperature is 800-1000 °C, the reaction chamber pressure is 150 mbar, the growth time is 10-48 hours. After the step (c) is completed, it also includes: stopping the introduction of process gases and cooling to room temperature at a rate of 5-10 °C / min.

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