Method for preparing cerium oxide film or doped cerium through low-temperature deposition

Abstract

The invention relates to the technical field of photoelectric materials, and discloses a method for preparing a cerium oxide film or doped cerium through low-temperature deposition, which is characterized in that a cerium precursor material with the molecular formula of Ce (C10H17O2) 4, the molecular weight of 816 and the volatilization temperature of 150-320 DEG C is used. The cerium precursor material not only has relatively low volatilization temperature, stable volatilization performance and relatively low residual rate, but also has relatively high purity. By adopting the method disclosed by the invention, the process temperature in the vapor deposition process can be reduced, the utilization rate of the mixed precursor material is improved, and the raw material cost is saved. The method can be applied to the fields of preparation of rare earth doped laser fibers, high-K gate dielectric materials, YBCO superconducting substrates and the like, and the preparation effect is excellent.

Description

Technical Field

[0001] The invention relates to the technical field of photoelectric materials, and in particular to a method for preparing a cerium oxide film or doping cerium by low-temperature deposition. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Cerium usually exists in related materials and devices in the form of oxide films or doping. The common methods for preparing cerium oxide films or achieving cerium doping are vapor deposition (CVD) or atomic layer deposition (ALD). These methods require the use of cerium precursors with volatile cerium sources. The volatility and stability of the precursors have an important influence on the process of preparing cerium oxide films or cerium doping.

[0004] In the preparation process of rare earth doped laser fiber, the gas phase doping method can achieve uniform doping of high concentration rare earth ions, and make the refractive index of the core and inner cladding have good repeatability. However, the color center generated by the existence of multiple valence states (Ⅱ, Ⅲ) of ytterbium ions is one of the main reasons for the photo-darkening effect of rare earth ytterbium doped laser fibers, thereby reducing the output power and stability of the fiber. In order to suppress the photo-darkening effect, co-doping cerium into ytterbium-containing optical fibers is an effective method. Rare earth chelates have a lower sublimation temperature and a higher saturated vapor pressure, and are easy to achieve high concentration of rare earth element doping. They are a promising rare earth doping source precursor in the gas phase doping preparation technology of rare earth doped laser fibers. In the disclosed rare earth chelate gas phase doping technology (Improved photodarkening resistivity in ytterbium-doped fiber lasers by cerium codoping [J]. Opt. Lett. 2009, 34 (8): 1285-1287.), rare earth ytterbium chelate (Yb (tmhd) 3) and cerium chelate (Ce (tmhd) 4) are used as precursors for doping rare earth ions. Due to the different structures of these two precursors, the volatilization temperature of cerium chelate (220-330°C) is higher than that of ytterbium chelate (169-170°C), so a higher heating temperature and heat preservation measures are required in the process of obtaining the cerium precursor gas. The difference between the volatilization temperatures of different precursors will make the parameters of the doping process more complicated.

[0005] Rare earth cerium oxide thin films are also used in high-K gate dielectric materials, CMOS devices and yttrium barium copper oxide (YBCO) superconducting substrate structures. The introduction of cerium can improve the performance of materials or devices. The preparation process of cerium oxide thin films in these structures is often formed by vapor deposition, and the cerium source raw materials used are usually volatile cerium chelate precursor Ce(tmhd)4.

[0006] In the existing process of preparing rare earth-doped laser optical fibers by vapor phase doping technology using rare earth cerium chelate precursors and preparing cerium oxide thin films by vapor phase deposition, the cerium precursors used have a high volatilization temperature (250-330°C), requiring high heating temperatures and insulation measures. In addition, the cerium precursors will decompose during the volatilization process, making it impossible to fully utilize the cerium source (residue>12%), thereby increasing the cost of raw materials and causing problems such as the inability to accurately control the concentration of the cerium element.

[0007] The purity of materials in the preparation of laser optical fibers and semiconductor devices is relatively high (material purity>99.999%, 5N), and excessive metal impurity content will seriously affect the performance of the device. For example, in laser optical fibers, some metal element impurities will produce absorption losses, which will reduce the optical output performance of the optical fiber. Therefore, the purity of the cerium chelate precursor used in the rare earth cerium oxide film or cerium element doping process used in related fields should meet the requirements. Summary of the invention

[0008] The purpose of the present invention is to provide a method for preparing cerium oxide thin films or doping cerium by low-temperature deposition in view of the defects of the current prior art, which solves the problems of high volatilization temperature and large residual amount of cerium chelate precursor, can effectively reduce the process temperature of preparing high-purity rare earth cerium oxide thin films or doping cerium elements by vapor deposition, and can improve the utilization rate of precursor materials and reduce raw material costs.

[0009] The technical solution of the present invention is as follows:

[0010] In one aspect, the present invention provides a method for preparing a cerium oxide film or doping cerium by low temperature deposition, which comprises the following steps:

[0011] Use Ce(C 10 H 17 O2)4 is used as a cerium precursor, which is volatilized by heating the cerium precursor, and then formed into an oxide film or doped into a matrix through vapor deposition or atomic layer deposition.

[0012] According to a preferred embodiment, the heating temperature is 150-320°C.

[0013] According to a preferred embodiment, the heating temperature is 160-280°C.

[0014] According to a preferred embodiment, the purity of the cerium precursor material is greater than 99.99%, preferably 99.999% to 99.99999%.

[0015] The cerium oxide film prepared by the above-mentioned preparation method can be deposited on an oxide substrate or a non-oxide substrate containing multiple elements, and the thickness of the formed cerium oxide film ranges from nm to μm. The utilization rate of the cerium precursor is high and the residual amount is low. After heating by the vapor deposition method, the residue of the cerium precursor is <10%, more specifically <2%.

[0016] When the cerium element is doped by the above preparation method, the cerium doping concentration is ≥ 0.0001%, and more preferably ≥ 0.001%. The matrix is ​​quartz, a fluorine-containing matrix, other oxide matrix or a non-oxide matrix containing multiple elements.

[0017] According to a preferred embodiment, the vapor deposition method includes MCVD, PECVD or PCVD.

[0018] According to a preferred embodiment, the cerium precursor Ce (C 10 H 17 O2)4 is prepared by the following method:

[0019] The preparation of cerium precursor material refers to the method disclosed in the invention patent CN108456219A, including cerium raw material treatment, chelation preparation reaction, post-reaction treatment and other processes; wherein the ligand molecular formula used in the reaction is C 10 H 19 O2, the reaction product was freeze-dried at <0℃.

[0020] Another aspect of the present invention provides a cerium precursor material having a molecular formula of Ce(C 10 H 17 O2)4, the volatilization temperature is 150~320℃.

[0021] The volatilization temperature of the cerium precursor material of the present application is lower than the volatilization temperature of the commonly used precursor Ce(tmhd)4, which is about 80 to 100°C. It volatilizes stably within the volatilization temperature and is not easy to decompose. It has a high utilization rate and a low residue. After heating by vapor deposition method, the residue of the cerium precursor is <10%, more specifically <2%.

[0022] The purity of the cerium precursor reagent of the present application is greater than 99.99%, and the preferred purity is 99.999% to 99.99999%.

[0023] Another aspect of the present invention provides a cerium precursor material Ce (C 10 H 17 Application of O2)4 in the preparation of cerium oxide thin films or doping cerium.

[0024] According to a preferred embodiment, cerium doping or preparation of rare earth cerium oxide thin films is achieved in the fields of rare earth doped laser optical fibers, high-K gate dielectric materials and yttrium barium copper oxide superconducting substrates.

[0025] Preferably, the cerium doping is more particularly effected in a quartz matrix.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. A method for preparing cerium oxide thin film or doping cerium by low temperature deposition, providing a new cerium precursor material with lower volatilization temperature and higher stability. The purity of the material can reach 5N or even 6N, which can be perfectly applied to the fields of laser optical fiber and semiconductor device preparation;

[0028] 2. A method for preparing cerium oxide thin film or doped cerium by low temperature deposition. On the one hand, the volatilization temperature of the cerium precursor material of the present application is 150-320°C, which is 80-100°C lower than the volatilization temperature of the commonly used cerium chelate precursor Ce(tmhd)4, and can save a lot of heating energy. On the other hand, the cerium precursor material of the present application has high stability and is not easy to decompose, and the residual amount after final volatilization is small, and the utilization efficiency of the material is high. The combination of the two aspects of performance reduces the use cost of the material.

[0029] 3. A method for preparing cerium oxide film or doping cerium by low-temperature deposition. The cerium precursor of the present application can be used to prepare high-purity cerium oxide film and to achieve uniform doping of cerium element into related matrix. It has good performance. The thickness of the prepared film ranges from nm to μm level; it is evenly distributed in the doped matrix and has a high doping concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the process of preparing a cerium-containing thin film or doping cerium elements by vapor deposition of a cerium precursor;

[0031] Figure 2 A schematic diagram of potential application areas of the cerium precursor of the present application;

[0032] Figure 3 is a mass spectrum characterization diagram of the cerium precursor (M) used in the present invention;

[0033] Figure 4 Comparison of volatility of different cerium precursors (M: present invention, Ce(tmhd)4: prior art). DETAILED DESCRIPTION

[0034] The specific embodiments listed in the present invention are only examples of the present invention, and the present invention is not limited to the specific embodiments described below. For those skilled in the art, any equivalent modifications and substitutions to the embodiments described below are also within the scope of the present invention. Therefore, the equal transformations and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturers are not specified for all reagents or instruments, they are all conventional products that can be purchased commercially. In order to better illustrate the present invention, numerous specific details are given in the specific embodiments below. It should be understood by those skilled in the art that the present invention can also be implemented without certain specific details. In other embodiments, the methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the purport of the present invention.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art. Unless otherwise specified, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0036] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0037] Example 1 A method for preparing a cerium precursor material

[0038] The cerium precursor material was prepared according to the method disclosed in the invention patent CN108456219A. The cerium raw material used in the reaction was cerium nitrate, and the purity after treatment was 5N (99.999%). The ligand molecular formula used was C 10 H 19 O2, the product after the reaction was freeze-dried at <0°C. The molecular formula of the prepared product is: Ce(C 10 H 17 O2)4, the molecular weight of the product was tested by high-resolution liquid chromatography-mass spectrometry, and the results showed that the molecular weight was 816 ( Figure 3 The results are shown as mass spectrometry results). The volatility of the obtained product was tested by thermogravimetric analyzer (test temperature range: room temperature-400°C, heating rate of 10°C / min, test atmosphere: air). The results showed that its initial volatility temperature was around 150°C, and the residual amount after volatility was around 2% (such as Figure 4The volatility test of the product was carried out on a thermogravimetric analyzer, the test temperature range was from room temperature to 400°C, the heating rate was 10°C / min, and the test atmosphere was air. The purity of the product was tested by ICP-MS, and the impurity content of rare earth elements and non-rare earth metal elements was tested. The result was a purity of >99.999% (5N) (the test results of impurity elements are shown in Table 1).

[0039] Table 1. Impurity content of high-purity rare earth cerium precursor materials (purity>5N)

[0040]

[0041] Example 2 A method for preparing a cerium precursor material

[0042] The preparation process described in Example 1 was adopted, except that the purity of the cerium raw material used in the preparation was >6N after treatment, the product after the reaction was freeze-dried at -10°C, and the purity of the prepared precursor material was tested by ICP-MS, and the purity of the material was >6N. The results are shown in Table 2.

[0043] Table 2. Impurity content of high-purity rare earth cerium precursor materials (purity>6N)

[0044]

[0045] Example 3 Application of a cerium precursor material

[0046] In this example, the cerium precursor material prepared in Example 1 was used to prepare a cerium oxide film by a vapor phase reaction deposition method.

[0047] The schematic diagram of the process of preparing cerium oxide thin film by vapor deposition method described in this embodiment is as follows Figure 1 As shown in a, it includes carrier gas, cerium doping precursor, auxiliary gas source, substrate source or vacuum control system, gas phase reaction zone, etc. The volatilized cerium precursor gas is introduced into the deposition zone through the carrier gas, and then a gas phase chemical reaction occurs to deposit a cerium oxide film or dope cerium into the substrate.

[0048] The purity of the cerium precursor material used is >5N. The cerium oxide film is formed by the PECVD method. 10g of the cerium precursor is weighed and placed in a sublimation bottle. It is heated until the precursor volatilizes. It is continued to be heated to 160°C and maintained. The volatilization rate is controlled at 6 to 8 grams per hour. The precursor volatiles containing the cerium element are brought into the reaction zone by high-purity argon gas, and then deposited on the silicon wafer substrate through a gas phase reaction to form a cerium oxide film with a thickness of μm level. After the deposition is completed, the precursor residue is weighed to be less than 0.1g, and the residual amount is less than 1%.

[0049] Example 4 Application of a cerium precursor material

[0050] In this example, the cerium precursor material prepared in Example 2 was used to prepare a cerium oxide film by a vapor phase reaction deposition method.

[0051] The vapor deposition method described in this embodiment is used to prepare the cerium oxide film. Figure 1 As shown in a, it includes carrier gas, cerium doping precursor, auxiliary gas source, substrate source or vacuum control system, gas phase reaction zone, etc. The volatilized cerium precursor gas is introduced into the deposition zone through the carrier gas, and then a gas phase chemical reaction occurs to deposit a cerium oxide film or dope cerium into the substrate.

[0052] The purity of the cerium precursor material used is >6N. The cerium oxide film is formed by the PECVD method. 12g of cerium precursor is weighed and placed in a sublimation bottle. When heated to about 150°C, the precursor material is observed to begin to volatilize. It is continued to be heated to 170°C and kept stable. The precursor volatiles containing cerium elements are brought into the reaction zone by high-purity argon gas, and the volatilization rate is controlled at 8 to 9 grams per hour. Then, the cerium oxide film is deposited on the SiO2 substrate through a gas phase reaction. The thickness of the film formed by the deposition is in the μm level. After the deposition is completed, the precursor residue weighs <0.1g, and the residual amount is less than 1%.

[0053] Example 5 Application of a cerium precursor material

[0054] This example uses the cerium precursor material prepared in Example 1 and adopts a vapor phase reaction deposition method to perform cerium doping.

[0055] The schematic diagram of the vapor deposition process of doping cerium in this embodiment is as follows Figure 1 As shown in FIG. 2 , it includes carrier gas, cerium doping precursor, auxiliary gas source, substrate source or vacuum control system, gas phase reaction zone, etc. The volatilized cerium precursor gas is introduced into the deposition zone through the carrier gas, and then a gas phase chemical reaction occurs to deposit a cerium oxide film or dope cerium into the substrate.

[0056] The material purity is 5N. The quartz rod is prepared by MCVD method, SiCl4 is used as the raw material for preparing the quartz rod, 20g of cerium precursor is weighed and put into the sublimation bottle, and then the sublimation bottle is heated to 220℃ and maintained, and the volatilization rate is controlled at 15-20g / hour. The volatiles are brought into the deposition furnace by high-purity argon gas, and the cerium element is uniformly doped into the SiO2 quartz preform formed by the reaction of SiCl4 in the deposition furnace. After the deposition is completed, the remaining residue is about 0.35g, and the residual amount is less than 2%. The doping content of cerium in the quartz preform is 0.0105% as measured by ICP-OES.

[0057] Example 6 Application of a cerium precursor material

[0058] This example uses the cerium precursor material prepared in Example 2 and adopts a vapor phase reaction deposition method to dope the cerium element.

[0059] The schematic diagram of the vapor deposition process of doping cerium in this embodiment is as follows Figure 1 As shown in FIG. 2 , it includes carrier gas, cerium doping precursor, auxiliary gas source, substrate source or vacuum control system, gas phase reaction zone, etc. The volatilized cerium precursor gas is introduced into the deposition zone through the carrier gas, and then a gas phase chemical reaction occurs to deposit a cerium oxide film or dope cerium into the substrate.

[0060] The material purity is 6N. The quartz rod is prepared by MCVD method, SiCl4 is used as the raw material for preparing the quartz rod, 30g of cerium precursor is weighed and put into the sublimation bottle, and then the sublimation bottle is heated to 180℃ and maintained, and the volatilization rate is controlled at 10-12g / hour. The volatiles are brought into the deposition furnace by high-purity argon gas, and the cerium element is uniformly doped into the SiO2 quartz preform formed by the reaction of SiCl4 in the deposition furnace. After the deposition is completed, the remaining residue is about 0.45g, and the residual amount is less than 1.5%. The doping content of cerium in the quartz preform is 0.0158% as measured by ICP-OES.

[0061] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A method for preparing cerium oxide thin film or doping cerium by low temperature deposition, characterized in that: The steps include: Use Ce(C 10 H 17 O2)4 is used as a cerium precursor, the cerium precursor is heated to volatilize, and then a cerium oxide film is formed or cerium is doped into the matrix through vapor deposition or atomic layer deposition.

2. The method for preparing cerium oxide thin film or doping cerium by low temperature deposition according to claim 1, characterized in that: The heating temperature is 150-320°C.

3. The method for preparing cerium oxide thin film or doping cerium by low temperature deposition according to claim 2, characterized in that: The heating temperature is 160-280°C.

4. The method for preparing cerium oxide thin film or doping cerium by low temperature deposition according to claim 1, characterized in that: The purity of the cerium precursor material is greater than 99.99%, and preferably the purity is between 99.999% and 99.99999%.

5. The method for preparing cerium oxide thin film or doping cerium by low temperature deposition according to claim 1, characterized in that: The vapor deposition method includes MCVD, PECVD or PCVD.

6. The method for preparing cerium oxide thin film or doping cerium by low temperature deposition according to claim 1, characterized in that: The cerium precursor Ce (C 10 H 17 O2)4 is prepared by the following method: Cerium salt raw materials and molecular formula C 10 H 19 The ligand of O2 undergoes a chelating reaction, and the product after the reaction is freeze-dried at <0°C.

7. A cerium precursor material Ce(C 10 H 17 Application of O2)4 in the preparation of cerium oxide thin films or doping cerium.

8. The cerium precursor material Ce (C) according to claim 7 10 H 17 O2)4 application, characterized in that Specifically, it is to realize cerium doping or prepare rare earth cerium oxide film in the fields of rare earth doped laser optical fiber, high-K gate dielectric material and yttrium barium copper oxide superconducting substrate.

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