An ultra-high vacuum magnetron sputtering device for controllable growth of silver nanofilms

Abstract

This invention belongs to the field of magnetron sputtering, specifically relating to an ultra-high vacuum magnetron sputtering device for the controllable growth of silver nanofilms. This invention innovates upon the shortcomings of existing technologies. It features four target positions, separated by stainless steel partitions to prevent sputtered particles from contaminating the other three targets while one target is in operation. Each target is equipped with independent power supply control. A 360° rotating and adjustable substrate stage is designed, allowing independent control of substrate temperature and bias. The substrate stage has four positions for placing the substrate, each separated by an independent stainless steel partition. The controllable target spacing creates conditions for the fabrication of functional thin film materials. In addition to independent rotation, the substrate stage can also be moved vertically to adjust the position of the target and the stage, meeting experimental requirements. The parameter conditions enable controllable growth of the silver thin film growth rate and nanoparticle size.

Description

Technical Field

[0001] This invention belongs to the field of magnetron sputtering, specifically relating to an ultra-high vacuum magnetron device for controllable growth of silver nanofilms. Background Technology

[0002] Magnetron sputtering (MS) deposition has become the most widely used technique for metal and compound thin film deposition and has been applied in many industries. MS technology has been continuously developed to improve target utilization, increase the ionization of sputtered materials, improve deposition rates, and reduce operating costs. Currently, MS is the dominant force in physical vapor deposition (PVD) for preparing advanced thin film materials. MS-prepared films possess excellent properties such as dense smoothness, strong adhesion to the substrate, high purity, low substrate temperature, and the ability to achieve irregular and large-area depositions. They are widely used in applications such as integrated circuit chip metallization, wear-resistant and corrosion-resistant coatings for mechanical parts, solar cells, and displays. MS discharge can be driven by DC power supply or RF power supply, or other periodic waveforms depending on the application. In magnetron sputtering discharge, its operating parameters, discharge characteristics, and plasma parameters, including particle density, electron and ion energy distribution, deposition rate, and ionization flux fraction, all affect the quality of the magnetron sputtered film.

[0003] The basic working principle of magnetron sputtering (MS) is as follows: A target is placed as the cathode, and an external magnetic field confines electrons near the target surface. Ions not confined by the magnetic field are accelerated through the cathode sheath, bombarding the target surface and causing material to be sputtered from the target. The sputtered atomic particles then deposit onto the substrate surface, ultimately forming a thin film. The external magnetic field confines electrons under low pressure, increasing the ionization rate, resulting in high-density plasma and a high ion flux bombarding the target. This improves the sputtering efficiency, as well as the density, purity, and growth rate of the thin film material, meeting the process requirements for high-quality thin film preparation. Sputtering deposition can be performed by sputtering compound targets in a mixture of inert working and reactive gases (e.g., oxygen, nitrogen, methane, etc.) or by sputtering elemental targets to deposit compound thin films. Whether in DC magnetron sputtering or RF magnetron sputtering discharge, the film material on the substrate mainly consists of neutral atoms ejected from the target surface. Summary of the Invention

[0004] The shortcomings of traditional laboratory magnetron sputtering systems are: (1) Usually, one set of parameters can only sputter one set of samples, so it is necessary to open the vacuum chamber and change the sample. Before preparing the second set of samples, it is necessary to continue to evacuate the vacuum and pre-sputter, etc., so the efficiency is often low; (2) The distance between the target and the substrate stage is often fixed, and the adjustment is more troublesome; (3) The target position is limited, and the target needs to be changed, which is inefficient.

[0005] This invention patent overcomes the shortcomings of the prior art and provides an ultra-high vacuum magnetron sputtering device for controllable growth of silver nanofilms with an adjustable substrate stage, as well as a design scheme for controllable growth of silver nanofilms.

[0006] The present invention provides an ultra-high vacuum magnetron sputtering device for controllable growth of silver nanofilms, comprising a magnetron sputtering cavity with a gas pipeline and a stainless steel pipeline connected to its side.

[0007] The gas pipeline is connected to a gas cylinder on the side away from the magnetic control cavity; the stainless steel pipeline is connected to an air outlet on the side away from the magnetic control cavity.

[0008] The bottom of the magnetron sputtering cavity is provided with a bottom plate, and the top of the bottom plate is divided into several identical magnetron sputtering areas A by a cross-shaped stainless steel plate; the interior of the magnetron sputtering area A is provided with a target material and a baffle located on top of the target material that can move horizontally;

[0009] The bottom of the lower base plate is equipped with several power systems; each target is connected to a power system.

[0010] The top of the magnetron cavity is provided with an upper cover plate and a corrugated tube passing through the center of the upper cover plate; the bottom of the corrugated tube is provided with a substrate stage; the substrate stage can rotate about the corrugated tube as an axis; the bottom of the substrate stage is divided into several identical magnetron sputtering regions B by a cross-shaped stainless steel plate, and a substrate is provided inside the magnetron sputtering region B.

[0011] Preferably, the power system includes a coaxial cable, a matching box, and a power supply connected in sequence.

[0012] Furthermore, the power supply is an radio frequency / DC power supply.

[0013] Preferably, a molecular pump and a mechanical pump are connected between the stainless steel pipe and the air outlet.

[0014] Preferably, the magnetically controlled cavity is connected to the lifting rod via a snap-fit, and the upper cover plate can be moved vertically via the lifting rod.

[0015] Preferably, the top of the bellows is provided with a handle, and the length of the bellows can be adjusted by the handle.

[0016] Preferably, the top of the upper cover plate is provided with an outer wall surface marked with a scale, and the outer wall surface marked with a scale surrounds the outside of the corrugated pipe.

[0017] Preferably, an air valve is provided between the air passage and the magnetic control cavity; a leakage valve and a mechanical valve are provided between the magnetic control cavity and the stainless steel pipe.

[0018] This invention also provides a method for preparing controllably grown silver nanofilms, using the aforementioned ultra-high vacuum magnetron sputtering device for controllably growing silver nanofilms, comprising the following steps:

[0019] S1: Evacuate the magnetron chamber for 2-3 hours and then fill it with protective gas;

[0020] S2: Start the power system and pre-sputter the target material onto the substrate using magnetron sputtering;

[0021] S3: Rotate the substrate stage so that the substrate after magnetron sputtering in step S2 corresponds to another target material, and perform magnetron sputtering.

[0022] S4: Repeat step S3 until a controllable silver nanofilm is obtained.

[0023] Preferably, the conditions for magnetron sputtering are: a distance of 45-55 mm between the target and the substrate, an RF power of 20-100 W, a deposition time of 2-15 min, and a working gas pressure of 6-8 Pa.

[0024] Preferably, in step S2, the target material is a pure silver target material, and the substrate is a silicon substrate.

[0025] The technical solution of the present invention has the following advantages compared with the prior art:

[0026] (1) There are four target positions designed in total, and stainless steel partitions separate the four targets to prevent the sputtered particles from contaminating the other three targets when one target is working.

[0027] (2) Each target location will be equipped with an independent power interface;

[0028] (3) At the substrate stage, a substrate stage that can be independently rotated 360° is designed. There are four positions for placing the substrate, and each position is separated by an independent stainless steel partition.

[0029] (4) The substrate stage is designed to be able to rotate independently and move vertically, thereby adjusting the position of the target and the substrate stage to meet experimental requirements and greatly improve the efficiency of sample preparation.

[0030] (5) Nanoparticles sputtered by radio frequency magnetron sputtering are uniform in size and can form relatively uniform nanoparticles on any substrate. Nanoparticles sputtered on various substrates have the advantages of good dispersion and uniform sputtering. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the ultra-high vacuum magnetron sputtering device for the controllable growth of silver nanofilms.

[0032] Figure 2 This is a schematic diagram of the lower target stage and the upper cover plate substrate stage of an ultra-high vacuum magnetron sputtering device for the controllable growth of silver nanofilms.

[0033] Figure 3 A schematic diagram of the vacuum and gas path of an ultra-high vacuum magnetron sputtering device for the controllable growth of silver nanofilms.

[0034] Figure 4 Figures a to c show the SEM images of the nano Ag film as a function of sputtering time; figure d shows the trend of the nano Ag film thickness as a function of sputtering time.

[0035] Explanation of reference numerals in the attached drawings: 1-Gas cylinder, 2-Gas pipeline, 3-Gas valve, 4-Bellower, 5-Substrate stage, 6-Baffle, 7-Target material, 8-Coaxial line, 9-Matching box, 10-Power supply, 11-Magnetic control cavity, 12-Leakage valve, 13-Mechanical valve, 14-Stainless steel pipeline, 15-Molecular pump, 16-Gas outlet, 17-Mechanical pump, 18-Lower base plate, 19-Upper cover plate, 20-Screw rod, 21-Outer wall surface marked with scale, 22-Handle, 23-Lifting rod, 24-Snap fastener, 25-Cross stainless steel plate, 26-Substrate. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0037] Example 1

[0038] An ultra-high vacuum magnetron sputtering device for controllable growth of silver nanofilms includes a magnetron sputtering cavity 11 with a gas passage pipe 2 and a stainless steel pipe 14 connected to its side.

[0039] Gas cylinder 1 is connected to the side of gas pipeline 2 away from the magnetic control cavity 11; gas outlet 16 is connected to the side of stainless steel pipeline 14 away from the magnetic control cavity 11; molecular pump 15 and mechanical pump 17 are connected between stainless steel pipeline 14 and gas outlet 16. Gas valve 3 is provided between gas pipeline 2 and magnetic control cavity 11; leakage valve 12 and mechanical valve 13 are provided between magnetic control cavity 11 and stainless steel pipeline 14.

[0040] The magnetically controlled cavity 11 is connected to the lifting rod 23 via the buckle 24, and the upper cover plate 19 can be moved vertically via the lifting rod 23.

[0041] The bottom of the magnetron sputtering cavity 11 is provided with a lower base plate 18, and the top of the lower base plate 18 is divided into several identical magnetron sputtering areas A by a cross stainless steel plate 25; inside the magnetron sputtering area A is a target material 7 and a baffle 6 located on top of the target material 7 and capable of horizontal movement.

[0042] Several power systems are provided at the bottom of the bottom plate 18; each target 7 is connected to a power system; the power system includes a coaxial cable 8, a matching box 9 and a power supply 10 connected in sequence. The power supply 10 is an RF / DC power supply.

[0043] The top of the magnetron sputtering cavity 11 is provided with an upper cover plate 19 and a bellows 4 that passes through the center of the upper cover plate 19; the bottom of the bellows 4 is provided with a substrate stage 5; the substrate stage 5 can rotate about the bellows 4 as an axis; the bottom of the substrate stage 5 is divided into several identical magnetron sputtering regions B by a cross stainless steel plate 25, and a substrate 26 is provided inside the magnetron sputtering region B.

[0044] The top of the spiral rod 20 is provided with a handle 22, and the length of the bellows 4 can be adjusted by the handle 22. The top of the upper cover plate 19 is provided with a spiral rod 20, and the height of the substrate stage 5 from the target material 7 can be adjusted by the spiral rod 20. The extension and retraction dimensions of the bellows 4 correspond to the outer wall surface 21 marked with a scale.

[0045] Example 2

[0046] A design for an ultra-high vacuum magnetron sputtering device for the controllable growth of silver nanofilms with an adjustable substrate stage includes a mechanical pump, a molecular pump, a stainless steel chamber, a matching box, an RF / DC power supply, a cover plate for the stainless steel chamber, a gas valve, a solenoid valve, a cooling water valve, an ionization vacuum gauge, a target material, and a substrate stage.

[0047] Figure 1 In the middle: Gas cylinder 1 can be connected to different gases according to experimental requirements, and argon is selected as the working gas;

[0048] Gas line pipe 2 is made of stainless steel. For details regarding gas line pipe 2 and the vacuum system, please refer to [link / reference]. Figure 3 . Figure 3 V0 corresponds to leakage valve 12, V1 corresponds to gas valves 3 and 13, V2 and V5 control the gas outlet at the front end and the gas inlet at the rear end of mass flow meter MFCⅠ, respectively. V3 and V6 control the gas outlet at the front end and the gas inlet at the rear end of mass flow meter MFCⅡ, respectively. V4 controls the gas outlet at the front end of mass flow meter MFCⅢ, while V7 and V8 share a single mass flow meter MFCⅢ, controlling its rear end gas inlet. The mass flow meter MFC controls the flow rate of gas entering the mixing chamber. Gas entering the vacuum chamber is controlled by V1. V9 is a bypass valve, DF1 is solenoid valve Ⅱ, DF2 is solenoid valve Ⅰ; R corresponds to mechanical pump 17; T corresponds to molecular pump 15; "This corresponds to a gas cylinder."

[0049] The tail end of the bellows 4 is fixed to the substrate stage 5, and its length is adjustable.

[0050] The substrate stage 5 can be adjusted vertically via four bellows. Detailed information about the substrate stage 5 can be found here. Figure 2There are four substrate positions: A, B, C, and D. The substrate stage is approximately 100mm in diameter and is divided into four areas by a cross-shaped stainless steel plate with a height of approximately 30mm. The four substrates are located in the four areas respectively.

[0051] The magnetron sputtering system is designed with four zones: I, II, III, and IV. Each zone is divided into four areas by a cross-shaped stainless steel plate 25 with a height of approximately 30 mm. Each zone can hold a target 7 of different materials with a diameter of approximately 72 mm. In this part, an automatically adjustable target baffle 6 is designed near each target 7. During the pre-sputtering process of magnetron sputtering, the baffle 6 can be used to block the target and prevent contamination of the silicon substrate on the top cover plate. After the pre-sputtering is completed, the baffle 6 can be removed by the electronic control system to deposit a silver thin film on the silicon substrate.

[0052] The magnetically controlled cavity 11, lower base plate 18, upper cover plate 19, and outer wall surface 21 marked with a scale are made of stainless steel; the handle 22 adjusts the height of the substrate stage via a bellows; 23 is marked as the lifting rod with the upper cover plate fixed on it; 24 is marked as the buckle on the upper cover plate when the cavity is closed; the height of the cross stainless steel plate 25 is 30 mm; the substrate 26 is fixed on the substrate stage of the upper cover plate, and a silicon substrate with a size of 2cm×2cm is selected.

[0053] Example 3

[0054] A method for preparing controllable growth of silver nanofilms, using the aforementioned ultra-high vacuum magnetron sputtering device for controllable growth of silver nanofilms, includes the following steps:

[0055] S1: Evacuate the magnetron chamber 11 for 2-3 hours and then fill it with protective gas;

[0056] S2: Start the power system, and after pre-sputtering, magnetron sputter the target 7 onto the substrate 26; during magnetron sputtering, the distance between the target 7 and the substrate 26 is 45-55 mm, the RF power is 20-100 W, the deposition time is 5 min, and the working pressure is 7 Pa. The target 7 is a pure silver target, and the substrate 26 is a silicon substrate.

[0057] S3: Rotate the substrate stage 5 so that the substrate 26 after magnetron sputtering in step S2 corresponds to another target 7, and perform magnetron sputtering; the distance between the target 7 and the substrate 26 during magnetron sputtering is 45-55 mm, the RF power is 20-100 W, the deposition time is 5 min, and the working pressure is 7 Pa.

[0058] S4: Repeat step S3 until a controllable silver nanofilm is obtained.

[0059] Example 4

[0060] Turn on the main control power switch, start the mechanical pump, then open solenoid valve DF2, and then slowly open V9 to full opening. Once the molecular pump reaches its operating pressure, close V9 and solenoid valve DF2. Open solenoid valve DF1, turn on the molecular pump power, and continue evacuating for 2-3 hours. Then, use the ionization vacuum gauge to observe the vacuum level until it reaches the target vacuum degree (<8×10⁻⁶). -6 Once the vacuum level reaches the target vacuum (Pa), sample preparation can begin. Afterward, the "inlet valve" for the corresponding gas on the flowmeter control panel can be opened counter-clockwise to introduce the working gas. In this embodiment, pure argon is used as the working gas.

[0061] Turn on the RF power supply. After the RF power supply is turned on, wait for it to enter normal operating mode. Then set the sputtering power, adjust the power, and turn on the corresponding matching box 9 knob. Adjust the required operating pressure, and then adjust the matching to make the reflected power zero, and perform pre-sputtering. The RF power during pre-sputtering is 40W, and the pre-sputtering time is 4 minutes. During pre-sputtering, use the baffle 6 to shield the substrate 26 to prevent particles from sputtering onto the substrate 26. In this embodiment, a pure silver target with a diameter of 3 is used.

[0062] The operating parameters were as follows: the distance between the target 7 and the substrate 26 was 50 mm; the substrate 26 was a silicon substrate; the working gas was pure Ar; the RF power was 100 W; the working pressure was approximately 7 Pa; and the deposition times were 5 minutes, 10 minutes, and 15 minutes, respectively, for a total of three sets of silver nanofilms. After pre-sputtering, the films were prepared according to the experimental parameters. The deposition time for the first set of samples was five minutes. After completing this set of samples, there was no need to turn off the vacuum, power supply, or gas. Simply adjust the RF power to 0 W, then rotate the horizontal substrate stage 90° clockwise. After aligning the target 7 with the new substrate position, readjust the RF power to 100 W, and the sputtering time was 10 minutes to prepare the second set of samples. All other parameters remained unchanged during this process. The preparation process for the third set of samples was the same as the second set; simply rotate the substrate stage 90° clockwise again, with all other steps remaining the same.

[0063] After preparing the three sets of samples, turn off the RF power supply, gas valve 3, gas cylinder valve, molecular pump 15, mechanical pump 17, open the leak valve 12 to remove the sample, and turn off the main power supply in sequence. To remove the sample and install the target material 7: slowly open the leak valve 12; after the pressure inside the cavity reaches atmospheric pressure, lift the cavity cover by adjusting the lifting rod 23, which is fixed with the upper cover plate 19.

[0064] Example 5: Detailed Operating Steps

[0065] (1) Start-up: Turn on the main control power switch, start the mechanical pump 17, then open the solenoid valve DF2, and then slowly open V9 to full opening. After reaching the working pressure of the molecular pump, close V9 and close the solenoid valve DF2. Open the solenoid valve DF1, turn on the power to the molecular pump, and continue evacuating for about 2-3 hours. Then, open the "ionization vacuum gauge" to observe the vacuum. Wait until the vacuum reaches the target vacuum level (<8×10). -6 Only after Pa) can sample preparation begin.

[0066] (2) Sample preparation: Turn the "inlet valve" ③ of the corresponding gas on the flowmeter control panel counterclockwise to introduce the working gas. The working gas used in this invention patent is argon. Turn on the RF power supply. After the RF power supply is turned on, wait for it to enter the normal operating state. Then set the sputtering power, adjust the power, and adjust the corresponding matching box 9 knob to ignite. Adjust the required working pressure, and then adjust the matching to make the reflection power zero, and perform pre-sputtering. After the pre-sputtering is completed, prepare the thin film according to the experimental parameters. In this embodiment, a pure silver target is used, and the target 7 has a diameter of 3 inches. The working parameters are: the target distance from the substrate is 50 mm, the working gas is pure Ar, the RF power is 20-80W, the deposition time is 4 minutes, and the working gas pressure is about 7Pa.

[0067] (3) After completing the sample preparation, turn off the radio frequency power supply, gas valve 3, gas cylinder valve, molecular pump 15, mechanical pump 17, open the leak valve 12 to take out the sample, and turn off the main power supply in sequence.

[0068] (4) Sample taking and target installation: Slowly open the air leakage valve 12; after the chamber reaches atmospheric pressure, lift the chamber cover by adjusting the lifting rod 23 with the upper cover plate fixed on it. Exchange the sample substrate, exchange or install the target material, and perform other necessary settings. Clean the chamber carefully with a vacuum cleaner; when adjusting the lifting rod, when it is about 5-8cm away from the top, hold the cover plate to accurately align it with the chamber position so that the latch 24 engages with the chamber, and then close the air leakage valve 12.

[0069] Effect Evaluation 1

[0070] like Figure 4 Figures a, b, and c show the surface morphology and cross-sectional morphology of nano-Ag deposited on Si substrates at different times, respectively. Figure 4Figure (d) shows the variation of nano-Ag thickness with sputtering time at an RF power of 100 W, with the nano-Ag deposition rate fitted by the red curve. The image shows that the size of the silver nanoparticles first increases and then decreases, exhibiting a dense state. The thickness increases approximately linearly with sputtering time, with the slope of the fitted red line being approximately 72.14. With other parameters fixed, the film thickness increases approximately linearly with RF power; therefore, at an RF power of 100 W, the film deposition rate can reach approximately 72.14 nm / min.

[0071] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A high-vacuum magnetron sputtering device for controllable growth of silver nanofilms, characterized in that, It includes a magnetically controlled cavity (11) with a gas pipeline (2) and a stainless steel pipeline (14) connected to its side. The gas pipeline (2) is connected to a gas cylinder (1) on the side away from the magnetic control cavity (11); the stainless steel pipeline (14) is connected to an air outlet (16) on the side away from the magnetic control cavity (11). The bottom of the magnetron sputtering cavity (11) is provided with a lower base plate (18), and the top of the lower base plate (18) is divided into several identical magnetron sputtering regions A by a cross stainless steel plate (25); the interior of the magnetron sputtering region A is provided with a target material (7) and a baffle (6) located on the top of the target material (7) and capable of horizontal movement. The bottom of the lower base plate (18) is provided with several power systems; each target material (7) is connected to a power system; The top of the magnetron cavity (11) is provided with an upper cover plate (19) and a corrugated tube (4) passing through the center of the upper cover plate (19); the bottom of the corrugated tube (4) is provided with a substrate stage (5); the substrate stage (5) can rotate about the corrugated tube (4) as an axis; the bottom of the substrate stage (5) is divided into several identical magnetron sputtering regions B by a cross stainless steel plate (25), and a substrate (26) is provided inside the magnetron sputtering region B; the power system includes a coaxial line (8), a matching box (9) and a power supply (10) connected in sequence; the power supply (10) is an RF / DC power supply; a molecular pump (15) and a mechanical pump (17) are connected between the stainless steel pipe (14) and the gas outlet (16).

2. The ultra-high vacuum magnetron sputtering device for controllable growth of silver nanofilms as described in claim 1, characterized in that, The magnetically controlled cavity (11) is connected to the lifting rod (23) via a buckle (24), and the upper cover plate (19) can be moved vertically via the lifting rod (23).

3. The ultra-high vacuum magnetron sputtering device for controllable growth of silver nanofilms as described in claim 1, characterized in that, The top of the corrugated pipe (4) is provided with a handle (22), and the length of the corrugated pipe (4) can be adjusted by the handle (22).

4. The ultra-high vacuum magnetron sputtering device for controllable growth of silver nanofilms as described in claim 1, characterized in that, The top of the upper cover plate (19) is provided with an outer wall surface (21) marked with a scale, which surrounds the outside of the bellows (4).

5. A method for preparing controllably grown silver nanofilms, characterized in that, The ultra-high vacuum magnetron sputtering device for controllable growth of silver nanofilms as described in any one of claims 1-4 comprises the following steps: S1: Evacuate the magnetron cavity (11) for 2-3 hours and then fill it with protective gas; S2: Start the power system and pre-sputter the target (7) on the substrate (26) by magnetron sputtering. S3: Rotate the substrate stage (5) so that the substrate (26) after magnetron sputtering in step S2 corresponds to another target (7) and perform magnetron sputtering; S4: Repeat step S3 until a controllable silver nanofilm is obtained.

6. The preparation method according to claim 5, characterized in that, The conditions for magnetron sputtering are as follows: the distance between the target (7) and the substrate (26) is 45-55 mm, the radio frequency power is 20-100 W, the deposition time is 2-15 min, and the working pressure is 6-8 Pa.

7. The preparation method according to claim 5, characterized in that, In step S2, the target material (7) is a pure silver target material, and the substrate (26) is a silicon substrate.

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