A method for preparing ultra-low doping concentration thin films using single-target magnetron sputtering

Abstract

The present invention relates to a method for preparing an ultra-low doping concentration film using single-target magnetron sputtering, comprising the following steps: preparing a doped solid solution block; cold pressing the doped solid solution block to obtain a doped sheet, and cutting the doped sheet into a fixed-size strip-shaped doped sheet; positioning the strip-shaped doped sheet; using a single-target magnetron sputtering instrument to prepare an ultra-low concentration rare earth-doped precious metal film on a Si sample substrate; achieving the purpose of secondary dilution of rare earth elements by single-target magnetron sputtering. The method provided by the present invention realizes the preparation of an ultra-low concentration rare earth-doped precious metal film while ensuring the density of the film, and utilizes a single crystal NaCl crystal instead of a Si sample substrate to achieve the separation of the film, the characterization of the elemental composition and other properties; by calibrating the concentration of the film prepared by the doped sheets at different positions, the quantitative controllable 10-1000ppm ultra-low concentration doped film can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth-doped noble metal film preparation, and in particular relates to a method for preparing an ultra-low doping concentration film by using single-target magnetron sputtering. Background Art

[0002] Metallic magnetic calorimetry (MMC) technology exploits the inverse relationship between the magnetization of paramagnets and T in ultra-low-concentration rare-earth-doped precious metal films (such as Au:Er, Au:Yb, and Ag:Er) at ultra-low temperatures, enabling the measurement of individual phonon variations. This technology has enabled high-resolution measurements of low-energy gamma rays, with an energy resolution exceeding 0.1%, 10 times higher than the currently highest energy resolution achieved with high-purity germanium (HPGe) gamma spectrometers. Currently, only a handful of research institutes and universities internationally possess the capability to develop MMC, with research at Heisenberg University in Germany leading the way. Research in China is still lacking. MMC technology is not only applicable to the measurement of alpha, beta, and gamma spectra for radiation metrology, but also to the precise measurement of astrophysical phenomena and cosmic rays, such as neutrino mass, dark matter, and magnetic monopoles.

[0003] In metal magnetocalorimetry, the detector chip is composed of a multi-layer thin film structure, in which the ultra-low concentration rare earth doped precious metal film (10-1000ppm) has a thermomagnetic conversion function and plays a vital role in the chip. The concentration of rare earth elements and the difference in the proportion of rare earth isotopes in the film have a significant impact on the efficiency of the entire detector. In the case of ultra-low concentration doping, rare earths (such as Er 3+ 、Yb 3+ ) form solid solutions with precious metals (such as Au and Ag). The three outer electrons of the rare earth ion become free conduction electrons. Ultra-low rare earth ion concentrations weaken the interactions between the conduction electrons, leaving only the partially filled 4f shell electrons contributing to the permanent magnetic moment. Therefore, quantitative optimization of rare earth element concentrations can reconcile the conflict between maximizing the magnetic moment and minimizing the interaction strength between the conduction electrons. In addition to the spin of the extranuclear electrons, the nuclear spin of rare earth ions also influences their magnetic behavior. For example, Er has six natural isotopes, of which Er-167 has a non-zero nuclear spin (I = 7 / 2). This interacts with the magnetic moment generated by the extranuclear electrons in the 4f shell, reducing paramagnetism and the output signal amplitude. Er-167 has a natural abundance of 23%. To minimize signal loss, stable isotope separation is required before the preparation of ultra-low-concentration rare earth-doped precious metal thin films. The separation of Er-167 isotopes is difficult and extremely expensive, posing a significant challenge to the preparation of ultra-low-concentration rare earth-doped metal thin films.

[0004] In order to obtain ultra-low concentration rare earth doped precious metal films, researchers have tried a variety of methods, such as thermal evaporation, ion beam evaporation, magnetron co-sputtering and other methods. Thermal evaporation is a method of using thermal energy to transform a substance from a solid state to a gaseous state. Ion beam evaporation is a special thermal evaporation method that uses an ion beam to transfer thermal energy to the surface of a substance, causing the substance to transform from a solid state to a gaseous state. During the ion beam evaporation process, the ion beam transfers thermal energy to the surface of the substance, thereby increasing the temperature of the substance and causing evaporation. Both methods can prepare thin film samples with doping levels of 10-1000ppm, but the density of the film is poor and defects are easily generated, which seriously affects the process performance. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing ultra-low doping concentration films using single-target magnetron sputtering, which is used to prepare ultra-low concentration rare earth-doped precious metal films and can achieve the preparation of precious metal films doped with isotope rare earths at the order of 10-1000ppm.

[0006] To achieve the above objectives, the present invention adopts a technical solution: a method for preparing an ultra-low doping concentration thin film by single-target magnetron sputtering, the method comprising the following steps:

[0007] S1. Preparation of doped solid solution block: preparing doped solid solution block by smelting precious metal element and rare earth element;

[0008] S2, cold pressing the doped solid solution block to obtain a doped sheet, and cutting the doped sheet into strip-shaped doped sheets of a fixed size;

[0009] S3. Positioning the strip-shaped doping sheet: fixing the noble metal target in a metal groove on the back of a doping sheet positioning device; the doping sheet positioning device includes a circular metal shell, and a graduated slide rail is provided at one diameter of the circular metal shell. The graduated slide rail includes a through groove of a set width. The strip-shaped doping sheet passes through the through groove and is precisely positioned on the noble metal target. The strip-shaped doping sheet is then adhered to the noble metal target using silver paste.

[0010] S4. Install the noble metal target and prepare an ultra-low concentration rare earth-doped noble metal thin film on a Si sample substrate using a single-target magnetron sputtering apparatus.

[0011] Furthermore, the method for preparing the doped solid solution block in step S1 includes the following specific steps:

[0012] S11, pickling: first, use acid solution to wash the rare earth element, and then use distilled water and anhydrous alcohol to wash the rare earth element;

[0013] S12. Melting: Weighing precious metal elements and rare earth elements in a specific ratio, placing them into a crucible of an arc melting furnace, evacuating the arc melting chamber, and injecting argon gas for melting to prepare a doped solid solution block.

[0014] Furthermore, the rare earth element is 4N high-purity rare earth Er, and the noble metal element is Au.

[0015] Furthermore, in step S12, the method of evacuating the arc melting chamber and then injecting argon gas is as follows: evacuating the arc melting chamber to 10 -6 Pa of high vacuum, and then inject 0.2MPa of 6N high-purity argon.

[0016] Furthermore, in step S12, before smelting, the following step is also included: turning on the magnetic stirring function.

[0017] Furthermore, step S2 further includes the following step: performing surface polishing on the strip-shaped doped sheet.

[0018] Furthermore, step S2 further includes the following specific steps:

[0019] ICP-MS is used to test the rare earth element concentration in the cutting residues at different positions of the doping sheet to calibrate the rare earth concentration in the doping sheet, thereby obtaining the rare earth concentration in the strip doping sheet; and the mass concentration of the rare earth in the strip doping sheet is controlled to be 5000-10000 ppm.

[0020] Furthermore, in step S3, the scale slide rail further includes a scale, and the scale is engraved on the front surface of the circular metal shell along the through groove;

[0021] The doping sheet positioning device further includes two positioning slides and a locking nut. The two positioning slides can slide in the through groove and can be fixed to the circular metal shell by the locking nut.

[0022] The noble metal target is fixed in a metal groove on the back side of the doping sheet positioning device through an elastic pressing sheet.

[0023] Furthermore, before the ultra-low concentration rare earth doped noble metal thin film is prepared on the Si sample substrate using the single target magnetron sputtering apparatus, step S4 further includes the following steps: pumping the sputtering chamber to 10 -6 Pa high vacuum, and then introduce 6N high-purity argon gas to make the pressure in the sputtering chamber reach 2Pa before thin film sputtering is carried out.

[0024] Furthermore, before step S4, the following steps are also included:

[0025] The center of the strip doped sheet is aligned with different designated scales of the scale, and a NaCl crystal substrate is used instead of a Si sample substrate to obtain a doped film corresponding to each designated scale by sputtering; the doped film corresponding to each designated scale of the NaCl crystal substrate is then placed in distilled water for film stripping, and the doped film corresponding to each designated scale is repeatedly cleaned and then dried; finally, the rare earth concentration in the doped film corresponding to each designated scale is tested by ICP-MS; thereby, a rare earth doping concentration curve of the doped film prepared when the center of the strip doped sheet is aligned with different designated scales of the scale is obtained.

[0026] The beneficial effects of the present invention are as follows: a method for preparing an ultra-low doping concentration thin film using single-target magnetron sputtering provided by the present invention is adopted, which comprises the following steps: preparing a doped solid solution block; cold pressing the doped solid solution block to obtain a doped sheet, and cutting the doped sheet into a fixed-size strip-shaped doped sheet; positioning the strip-shaped doped sheet based on a doped sheet positioning device; and preparing an ultra-low concentration rare earth-doped precious metal thin film on a Si sample substrate using a single-target magnetron sputtering apparatus, thereby achieving the purpose of secondary dilution of rare earth elements by single-target magnetron sputtering. The method provided by the present invention realizes the preparation of an ultra-low concentration rare earth-doped precious metal thin film while ensuring the density of the thin film, and uses a single crystal NaCl crystal instead of a Si sample substrate to realize the separation of the thin film, the characterization of the elemental composition and other properties; by calibrating the concentration of the thin film prepared by the doped sheet at different positions, the quantitative controllable ultra-low concentration doped thin film of 10-1000ppm can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic flow chart of a method for preparing an ultra-low doping concentration thin film by using single-target magnetron sputtering according to an embodiment of the present invention;

[0028] Figure 2 It is a front schematic diagram of the doping sheet positioning device described in an embodiment of the present invention.

[0029] Figure 3 It is a schematic diagram of the back side of the doping piece positioning device described in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be further clearly and completely described below in conjunction with the drawings and examples. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] Currently, co-sputtering of rare earth and precious metal targets can produce thin films with good density, but it remains significantly limited in the preparation of doped films at concentrations of 10-1000 ppm. The extremely complex isotope preparation process and the difficulty in obtaining large quantities of isotope targets significantly restrict the preparation of isotope targets. Therefore, to address the difficulties in preparing ultra-low concentration rare earth-doped precious metal films, particularly isotope-doped films, the inventors have optimized and improved existing thin film preparation methods, achieving quantitative and controllable ultra-low concentration doped films using single-target magnetron sputtering.

[0032] In an embodiment of the present invention, arc melting technology is used to prepare a relatively low concentration of rare earth and precious metal solid solution blocks, and the rare earth element concentration is first diluted once to form a low-concentration doped sheet. Then, doped sheets of regular size are prepared by cold pressing, cutting, polishing and other processes, and their concentrations are characterized. Based on a self-designed doped sheet positioning device, the doped sheets of regular size are bonded to the precious metal target material by silver paste, so as to achieve the purpose of secondary dilution of rare earth elements by single-target magnetron sputtering. Under the premise of ensuring the density of the film, the preparation of ultra-low concentration rare earth doped precious metal films is realized, and single crystal NaCl crystals are used instead of Si sample substrates to realize the separation of the film, the characterization of elemental composition and other properties. By calibrating the concentration of films prepared by doped sheets at different positions, quantitative control of ultra-low concentration doped films of 10-1000ppm can be achieved.

[0033] like Figure 1 、 Figure 2 As shown, an embodiment of the present invention provides a method for preparing an ultra-low doping concentration thin film by using single-target magnetron sputtering, the method comprising the following steps:

[0034] S1. Preparation of doped solid solution block: preparing doped solid solution block by smelting precious metal element and rare earth element;

[0035] Specifically, the method for preparing the doped solid solution block in step S1 includes the following specific steps:

[0036] S11, pickling: first, washing the rare earth element with acid to remove the oxide layer and impurities on the surface of the rare earth element; then washing the rare earth element with distilled water and anhydrous alcohol to remove the acid remaining on the surface of the rare earth element;

[0037] S12. Melting: Weigh the precious metal elements and rare earth elements in a specific ratio, put them into the crucible of the arc melting furnace, evacuate the arc melting chamber and inject argon gas for melting to prepare a doped solid solution block, so that the magnetic rare earth elements are evenly distributed in the precious metal block, and realize the first dilution of the rare earth elements.

[0038] Optionally, the rare earth element in step S11 is 4N high-purity rare earth particles with a purity of 99.99%.

[0039] In a specific embodiment, the rare earth element is erbium Er, and the noble metal element is gold Au.

[0040] Specifically, the acid solution in step S11 is selected from one or a combination of dilute nitric acid, dilute sulfuric acid, and dilute hydrochloric acid.

[0041] Specifically, in step S12, when the precious metal element and the rare earth element weighed in a specific ratio are placed in the crucible of the arc melting furnace, the rare earth element is placed above the precious metal element.

[0042] Specifically, in step S12, the method of evacuating the arc melting chamber and then injecting argon gas is as follows: evacuating the arc melting chamber to 10 -6 Pa of high vacuum, and then inject 0.2MPa of 6N high-purity argon (purity of 99.9999%).

[0043] Specifically, in step S12, before smelting, the following steps are also included: turning on the magnetic stirring function to repeatedly turn the metal block during the smelting process to make the magnetic rare earth elements evenly distributed in the precious metal block, and performing the first dilution of the rare earth elements.

[0044] Specifically, in the doped solid solution block prepared in step S12, the mass concentration of the rare earth element is 5000-10000 ppm.

[0045] S2, cold pressing the doped solid solution block to obtain a doped sheet, and cutting the doped sheet into strip-shaped doped sheets of a fixed size;

[0046] Specifically, the thickness of the doped sheet in step S2 is 1-3 mm.

[0047] Specifically, the length of the strip doping sheet in step S2 is 1-10 mm, and the width is 1-5 mm; by adjusting the length and width of the strip doping sheet, combined with the positioning of the doping sheet in the subsequent step S3, the purpose of the second dilution of rare earth elements by single-target magnetron sputtering can be achieved.

[0048] Specifically, step S2 also includes the following steps: polishing the surface of the strip-shaped doped sheet to remove surface cracks and residues that may be formed during the processing, thereby ensuring that the concentration of rare earth elements doped in the thin film prepared in the subsequent sputtering process is uniform, while ensuring the repeatability of the sputtering process.

[0049] Specifically, step S2 also includes the following steps: using inductively coupled plasma mass spectrometry (ICP-MS) to test the rare earth element concentration in the cutting residues at different positions of the doping sheet to calibrate the rare earth concentration in the doping sheet, and then obtain the rare earth concentration in the strip doping sheet; and controlling the mass concentration of the rare earth in the strip doping sheet to 5000-10000 ppm.

[0050] S3. Positioning the strip-shaped doping sheet: fixing the noble metal target in a metal groove on the back of a doping sheet positioning device; the doping sheet positioning device includes a circular metal shell, a graduated slide rail is provided at one diameter of the circular metal shell, the graduated slide rail includes a through groove of a set width, the through groove passes through the circular metal shell, the strip-shaped doping sheet is precisely positioned on the noble metal target through the through groove, and the strip-shaped doping sheet is adhered to the noble metal target using silver paste;

[0051] Specifically, the scale rail further includes a scale, which is engraved on the front surface of the circular metal housing (i.e., the front surface of the doping sheet positioning device) along the through groove. The center of the front surface of the circular metal housing is set as the zero scale of the scale, and the scale has a graduation value of 1 mm.

[0052] Specifically, the doping sheet positioning device further includes two positioning sliders and a locking nut. The two positioning sliders can slide in the through-groove and can be fixed to the circular metal shell via the locking nut. The strip-shaped doping sheet is placed in a rectangular groove formed by the two positioning sliders and the through-groove, and the two positioning sliders are slid in the through-groove so that the center of the strip-shaped doping sheet is aligned with the set scale of the scale. The two positioning sliders are then fixed to the circular metal shell via the locking nut. This allows the strip-shaped doping sheet to be precisely positioned at the set position on the precious metal target, and the strip-shaped doping sheet can then be adhered to the precious metal target using silver paste.

[0053] Optionally, the noble metal target is made of the noble metal element.

[0054] Optionally, the noble metal target is fixed in a metal groove on the back side of the doping sheet positioning device by an elastic pressing sheet.

[0055] Specifically, the silver paste is an adhesive with electrical conductivity, wherein the conductive medium is silver.

[0056] S4. Install the precious metal target and use a single-target magnetron sputtering device to prepare ultra-low concentration rare earth-doped precious metal films on Si sample substrates.

[0057] Specifically, step S4 further includes the following steps: before preparing the ultra-low concentration rare earth doped noble metal thin film on the Si sample substrate using the single target magnetron sputtering instrument, the sputtering chamber is evacuated to 10 -6 Pa high vacuum, and then introduce 6N high-purity argon gas to make the pressure in the sputtering chamber reach 2Pa before thin film sputtering is carried out.

[0058] Specifically, before step S4, the following steps are further included: aligning the center of the strip doping sheet with different designated scales of the scale, replacing the Si sample substrate to be sputtered with a NaCl crystal substrate, and sputtering to obtain a doped film corresponding to each designated scale; then placing the doped film corresponding to each designated scale of the NaCl crystal substrate in distilled water for film stripping, then repeatedly washing the doped film corresponding to each designated scale and drying it at 120° C., and finally using inductively coupled plasma mass spectrometry (ICP-MS) to measure the rare earth concentration in the doped film corresponding to each designated scale. Then, the change in the rare earth concentration of the doped film prepared when the center of the strip doping sheet is aligned with the different designated scales of the scale is calibrated, and a rare earth concentration curve of the doped film prepared when the center of the strip doping sheet is aligned with the different designated scales of the scale is obtained, thereby achieving continuous adjustment of the rare earth concentration in the film from 10 to 1000 ppm.

[0059] The specific embodiments of the present invention are further described below through examples.

[0060] Example 1: Single-target magnetron sputtering method for preparing ultra-low doping concentration thin films

[0061] (1) Preparation of doped solid solution blocks: A doped solid solution block is prepared using a noble metal element, gold (Au), and a rare earth element, erbium (Er). The method for preparing the doped solid solution block comprises the following specific steps:

[0062] Acid washing: First, use dilute nitric acid to wash the 4N high-purity rare earth particles Er to remove the oxide layer and impurities on the surface of the rare earth particles Er; then use distilled water and anhydrous alcohol to wash the rare earth particles Er to remove the acid remaining on the surface of the rare earth particles Er;

[0063] Melting: Weigh 10.22g of precious metal Au and 0.108g of rare earth Er in a specific ratio, put them into the crucible of the arc melting furnace, and place the rare earth Er on top of the precious metal Au; in order to avoid oxidation of the rare earth during the melting process, the arc melting chamber is pumped to 10 -6Pa high vacuum, and then inject 0.2MPa 6N high-purity argon; then turn on the magnetic stirring function and perform arc melting, so that the metal block is repeatedly turned over during the melting process to make the magnetic rare earth elements evenly distributed in the precious metal block, and dilute the rare earth elements for the first time to prepare a doped solid solution block.

[0064] (2) Cold pressing the doped solid solution block and cutting it into strip-shaped doped sheets: cold pressing the doped solid solution block to obtain a doped sheet with a thickness of 2 mm, and cutting the doped sheet into strip-shaped doped sheets with a length of 5 mm and a width of 3 mm; then polishing the surface of the strip-shaped doped sheets to remove surface cracks and residues that may be formed during the processing, thereby ensuring that the concentration of rare earth elements doped in the thin film prepared in the subsequent sputtering process is uniform, while ensuring the repeatability of the sputtering process.

[0065] ICP-MS was used to measure the rare earth element concentration in the cut residue at different locations of the doping sheet to calibrate the rare earth concentration in the doping sheet, thereby obtaining the rare earth concentration in the strip doping sheet. The rare earth concentration in the strip doping sheet can be controlled to 5,000-10,000 ppm by adjusting the mass ratio of the precious metal Au and the rare earth Er during the smelting process.

[0066] In this Example 1, the amount of precious metal element Au during the smelting process was 10.22 g, and the amount of rare earth element Er was 0.108 g. The measured mass concentration of the rare earth in the strip-shaped doped sheet was 9500 ppm.

[0067] (3) Positioning the strip-shaped doping sheet: fixing the noble metal Au target in the metal groove on the back of the doping sheet positioning device through an elastic pressing sheet;

[0068] The doping sheet positioning device includes a circular metal shell, two positioning sliders, and a locking nut. A scale slide is provided at one diameter of the circular metal shell. The scale slide includes a scale and a through slot of a set width. The through slot passes through the circular metal shell. The strip doping sheet passes through the through slot and is precisely positioned on the precious metal Au target. The strip doping sheet is then adhered to the precious metal Au target using silver paste.

[0069] The scale is engraved on the front of the circular metal shell along the through groove, the center of the front of the circular metal shell is set as the zero scale of the scale, and the graduation value of the scale is 1mm.

[0070] The two positioning sliders can slide in the through-grooves and can be fixed to the circular metal shell via locking nuts. The strip-shaped doping sheet is placed in a rectangular groove formed by the two positioning sliders and the through-grooves, and the two positioning sliders are slid in the through-grooves so that the center of the strip-shaped doping sheet is aligned with the set scale of the scale. The two positioning sliders are then fixed to the circular metal shell via locking nuts. This allows the strip-shaped doping sheet to be precisely positioned at the set position on the precious metal Au target, and the strip-shaped doping sheet can then be adhered to the precious metal Au target using silver paste.

[0071] (4) Obtaining a rare earth doping concentration curve of the doped film prepared when the center of the strip doped piece is aligned with different designated scales of the scale: by aligning the center of the strip doped piece with different designated scales of the scale, the strip doped piece is accurately positioned at different positions on the precious metal Au target; then, when the center of the strip doped piece is aligned with each designated scale, a single-target magnetron sputtering device is used to prepare a doped film corresponding to each designated scale on a NaCl crystal substrate, and by utilizing the solubility of NaCl, the doped film corresponding to each designated scale of the NaCl crystal substrate is placed on The film is stripped in distilled water, and then the doped film corresponding to each specified scale is repeatedly cleaned and dried at 120°C. Finally, the concentration of the doped rare earth element in the doped film corresponding to each specified scale is tested by inductively coupled plasma mass spectrometry (ICP-MS); then, the change in the doped rare earth concentration in the doped film prepared when the center of the strip doped piece is aligned with different specified scales of the scale is calibrated, and a curve of the doped rare earth concentration in the doped film prepared when the center of the strip doped piece is aligned with different specified scales of the scale is obtained, thereby achieving continuous adjustment of the doped rare earth concentration in the film from 10 to 1000 ppm.

[0072] Among them, the NaCl crystal substrate and the normal Si sample substrate have the same size and dimensions, and are placed in the same position, which can equivalently simulate the rare earth doping concentration curve in the doped film prepared when the center of the strip doping piece is aligned with different specified scales of the scale.

[0073] In Example 1, when the center of the doped strip was aligned with the zero mark on the scale, the rare earth doping concentration in the prepared doped film was 380 ppm. When the center of the doped strip was aligned with the 25 mm mark on the scale, the rare earth doping concentration in the prepared doped film was 4200 ppm.

[0074] (5) Using a single-target magnetron sputtering instrument to prepare ultra-low concentration rare earth doped precious metal thin films on Si sample substrates: First, according to the rare earth concentration curve of the doped thin film prepared when the center of the strip doped piece is aligned with different designated scales of the scale, according to the rare earth concentration of the doped thin film to be prepared, the scale of the scale to which the center of the strip doped piece should be aligned is selected, and the strip doped piece is positioned; then, the precious metal Au target is installed, and the sputtering chamber is pumped to 10 -6 Pa high vacuum, and then 6N high-purity argon gas is introduced to make the gas pressure in the sputtering chamber reach 2Pa before thin film sputtering. Ultra-low concentration rare earth-doped precious metal films are prepared on Si sample substrates using a single-target magnetron sputtering instrument.

[0075] The methods described herein are not limited to the specific embodiments described. The above embodiments are merely illustrative of the present invention, and the present invention may also be implemented in other specific ways or in other specific forms without departing from the gist or essential characteristics of the present invention. Therefore, the embodiments described herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is to be determined by the appended claims, and any variations that are equivalent to the intent and scope of the claims are intended to be within the scope of the present invention.

Claims

1. A method for preparing an ultra-low doping concentration thin film using single-target magnetron sputtering, characterized in that: The method comprises the following steps: S1. Preparation of doped solid solution block: preparing a doped solid solution block by smelting a noble metal element and a rare earth element; the method for preparing the doped solid solution block in step S1 comprises the following specific steps: S12. Melting: Weighing a noble metal element and a rare earth element according to a specific ratio, placing the elements into a crucible of an arc melting furnace, evacuating the arc melting chamber, and injecting argon gas for melting to prepare a doped solid solution block; In the doped solid solution block, the mass concentration of the rare earth element is 5000-10000 ppm; S2, cold pressing the doped solid solution block to obtain a doped sheet, and cutting the doped sheet into strip-shaped doped sheets of a fixed size; S3. Positioning the strip-shaped doping sheet: fixing the noble metal target in a metal groove on the back of a doping sheet positioning device; the doping sheet positioning device includes a circular metal shell, a graduated slide rail is provided at one diameter of the circular metal shell, the graduated slide rail includes a through groove of a set width, the strip-shaped doping sheet passes through the through groove and is precisely positioned on the noble metal target, and the strip-shaped doping sheet is adhered to the noble metal target using silver paste; the graduated slide rail also includes a scale, and the scale is engraved on the front of the circular metal shell along the through groove; S4, installing the noble metal target, and using a single-target magnetron sputtering apparatus to prepare an ultra-low concentration rare earth-doped noble metal thin film on a Si sample substrate; before step S4, the following steps are also included: The center of the strip doping sheet is aligned with different designated scales of the scale, and a NaCl crystal substrate is used instead of a Si sample substrate to obtain a doped film corresponding to each designated scale by sputtering; the doped film corresponding to each designated scale of the NaCl crystal substrate is then placed in distilled water for film stripping, and the doped film corresponding to each designated scale is repeatedly cleaned and then dried; finally, the rare earth concentration in the doped film corresponding to each designated scale is tested by ICP-MS; and a rare earth doping concentration curve of the doped film prepared when the center of the strip doping sheet is aligned with different designated scales of the scale is obtained, thereby achieving continuous adjustment of the rare earth doping concentration in the film from 10 to 1000 ppm.

2. The method for preparing an ultra-low doping concentration thin film by single-target magnetron sputtering according to claim 1, characterized in that: The method for preparing the doped solid solution block in step S1 includes the following specific steps: S11. Pickling: First, use acid solution to wash the rare earth element, and then use distilled water and anhydrous alcohol to clean the rare earth element.

3. The method for preparing an ultra-low doping concentration thin film by single-target magnetron sputtering according to claim 1, characterized in that: The rare earth element is 4N high-purity rare earth Er, and the noble metal element is Au.

4. The method for preparing an ultra-low doping concentration thin film by single-target magnetron sputtering according to claim 1, wherein: In step S12, the method of evacuating the arc melting chamber and then injecting argon gas is as follows: evacuating the arc melting chamber to 10 -6 Pa of high vacuum, and then inject 0.2MPa of 6N high-purity argon.

5. The method for preparing an ultra-low doping concentration thin film by single-target magnetron sputtering according to claim 1, characterized in that: In step S12, before smelting, the following step is also included: turning on the magnetic stirring function.

6. The method for preparing an ultra-low doping concentration thin film by single-target magnetron sputtering according to claim 1, characterized in that: Step S2 also includes the following step: polishing the surface of the strip-shaped doped sheet.

7. The method for preparing an ultra-low doping concentration thin film by single-target magnetron sputtering according to claim 1, characterized in that: Step S2 also includes the following specific steps: ICP-MS is used to test the rare earth element concentration in the cutting residues at different positions of the doping sheet to calibrate the rare earth concentration in the doping sheet, thereby obtaining the rare earth concentration in the strip-shaped doping sheet.

8. The method for preparing an ultra-low doping concentration thin film by single-target magnetron sputtering according to claim 1, characterized in that: In step S3, the doping sheet positioning device further includes two positioning sliders and a locking nut. The two positioning sliders can slide in the through groove and can be fixed to the circular metal housing by the locking nut. The noble metal target is fixed in a metal groove on the back side of the doping sheet positioning device through an elastic pressing sheet.

9. The method for preparing an ultra-low doping concentration thin film by single-target magnetron sputtering according to claim 1, characterized in that: Before the single-target magnetron sputtering apparatus is used to prepare an ultra-low concentration rare earth-doped noble metal thin film on a Si sample substrate, step S4 further includes the following steps: evacuating the sputtering chamber to 10 -6 Pa high vacuum, and then introduce 6N high-purity argon gas to make the pressure in the sputtering chamber reach 2Pa before thin film sputtering is carried out.

Images