A sputtering target for a thin film resistor, a preparation method thereof and an application thereof

Abstract

A sputtering target for thin film resistors, a preparation method and an application thereof provided by the present invention improve the grain size and strength by adding appropriate additives to Si, Cr, Ni, and Al, improve the resistivity and adjust the temperature coefficient of resistance by adding appropriate oxides, prepare intermediate powder from raw materials by alloy melting and gas atomization method, and sinter and form a high-density, uniform composition distribution, and fine grain size sputtering target by spark plasma sintering method and vacuum hot pressing sintering method, providing more additive choices for the preparation of the target, not only relying on the addition of rare earth elements. The initial resistance value of the thin film resistor prepared by the sputtering target is ≥2 kΩ, and the temperature coefficient of resistance is ≤±10 ppm / °C, having the advantages of high stability and high resistance value.

Description

Technical Field

[0001] The present invention relates to the technical fields of electronic materials and metallurgy technologies, and particularly relates to a sputtering target for a thin-film resistor, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of modern electronic technologies, the performance requirements for electronic components in high-tech fields such as automotive electronics, aerospace, and communication systems are getting higher and higher. As an important electronic component, thin-film resistors are particularly suitable for high-precision electronic instruments such as aerospace and national defense, and their performance directly affects the accuracy and stability of electronic devices.

[0003] The performance of thin-film resistors mainly depends on the film layer material and the film-forming process. Magnetron sputtering technology has long been widely used in resistor film production, and has great advantages in terms of resistance value stability and output. However, the component ratio and preparation method of the target restrict the stability and reliability of thin-film resistors.

[0004] Most of the currently produced high-resistance sputtering targets are produced by vacuum induction melting. However, segregation is likely to occur during the preparation of the target, and rare earth elements must be added to reduce element segregation. The tissue distribution is uneven, and the grains are generally coarse, resulting in a relatively high resistance temperature coefficient of the thin-film resistor obtained by sputtering and limited stability; for the target material system used to reduce the resistance temperature coefficient of the film resistor, some high-resistance characteristics are sacrificed, resulting in a relatively low initial resistance value of the sputtered thin-film resistor, leading to a decline in film quality and anti-interference ability and an increase in the risk of leakage current, making it difficult to meet the use requirements of high-precision resistor components. Summary of the Invention

[0005] In view of the problems existing in the background art, the present invention provides a sputtering target for a thin-film resistor, a preparation method thereof, and an application thereof. By adding appropriate additives to improve the grain size and strength, adding appropriate oxides to improve the resistivity and adjust the resistance temperature coefficient, a highly dense and uniform sputtering target is prepared by using a spark plasma sintering method and a vacuum hot pressing sintering method, providing more additive options for the preparation of the target and not only relying on the addition of rare earth elements. The initial resistance value of the thin-film resistor prepared by the sputtering target is ≥2 kΩ, and the resistance temperature coefficient is ≤±10 ppm / °C, having the advantages of high stability and high resistance value.

[0006] The specific content of the invention is as follows:

[0007] According to a first aspect of the present invention, there is provided a preparation method of a sputtering target for a thin-film resistor, and the preparation method specifically includes the following steps:

[0008] S1. Using Si, Cr, Ni, Al, an additive, and an optional oxide as raw materials, preparing the raw materials into intermediate powder by an alloy melting gas atomization method;

[0009] S2. Weigh a quantitative amount of the intermediate powder and load it into a graphite mold, then sinter it into a compact to obtain a target blank.

[0010] S3. Perform surface polishing on the target blank and machine it to the target size to obtain the target material.

[0011] By mass fraction, the addition amount of Si is 30 - 60 wt%, the addition amount of Cr is 20 - 40 wt%, the addition amount of Ni is 15 - 30 wt%, the addition amount of Al is 2 - 8 wt%, the addition amount of the additive is 0.1 - 5 wt%, and the addition amount of the oxide is 0 - 12.5 wt%.

[0012] The additive is selected from one or more of Mo, Ti, and rare earth elements.

[0013] The oxide is selected from one or more of CuO, MoO₂, RuO₂, SiO₂, and V₂O₅.

[0014] Optionally, when the raw material contains an oxide, the method of preparing the intermediate powder from the raw material by alloy melting gas atomization includes:

[0015] Perform alloying treatment on Si, Cr, Ni, Al, and the additive using a vacuum induction furnace to form an alloyed melt, and then use high-pressure Ar as the atomizing gas to prepare the melt into alloy powder.

[0016] Mix the alloy powder with the oxide powder to obtain the intermediate powder.

[0017] The temperature of the alloying treatment is 1200 - 1700 °C.

[0018] The pressure of the atomizing gas is 1.5 - 10 MPa.

[0019] Optionally, when mixing the alloy powder with the oxide powder, the three-dimensional mixing method or the vibration mixing method is used.

[0020] Optionally, when the raw material does not contain an oxide, the method of preparing the intermediate powder from the raw material by alloy melting gas atomization includes:

[0021] Perform alloying treatment on Si, Cr, Ni, Al, and the additive using a vacuum induction furnace to form an alloyed melt, and then use high-pressure Ar as the atomizing gas to prepare the melt into the intermediate powder.

[0022] The temperature of the alloying treatment is 1200 - 1700 °C.

[0023] The pressure of the atomizing gas is 1.5 to 10 MPa.

[0024] Optionally, the particle size of the intermediate powder is 10 to 60 µm.

[0025] Optionally, in step S2, the sintering and forming is carried out by vacuum hot pressing sintering, and the vacuum hot pressing sintering is carried out under the protection of Ar, the vacuum degree is lower than 500 Pa, the temperature is 1000 to 1250 °C, and the pressure is 15 to 60 MPa.

[0026] Optionally, in step S2, the sintering and forming is carried out by spark plasma sintering, the vacuum degree of the spark plasma sintering is 20 to 100 Pa, the sintering temperature is 900 to 1100 °C, and the pressure is 5 to 20 MPa.

[0027] According to the second aspect of the present invention, a sputtering target prepared by the above preparation method is provided.

[0028] Optionally, the density of the sputtering target is ≥95%.

[0029] According to the third aspect of the present invention, an application of a sputtering target for a thin film resistor is provided, and the sputtering target is used as a sputtering target for a thin film resistor.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] The present invention provides a sputtering target for a thin film resistor, a preparation method and an application thereof. The preparation method includes the following steps: using Si, Cr, Ni, Al, an additive and an optional oxide as raw materials, and preparing the raw materials into an intermediate powder by an alloy melting gas atomization method; weighing a quantitative intermediate powder and loading it into a graphite mold, sintering and forming to obtain a target blank; performing surface polishing treatment on the target blank and machining to obtain a target material according to the target size. The sputtering target is obtained through the above preparation method, and the sputtering target is used as a sputtering target for a thin film resistor.

[0032] The preparation method of the sputtering target for a thin film resistor provided by the present invention improves the grain size and strength by adding a suitable additive, improves the resistivity and adjusts the resistance temperature coefficient by adding a suitable oxide, prepares an intermediate powder with uniform particle size by an alloy melting gas atomization method, and then prepares a sputtering target with high density, uniform composition distribution and fine crystal grains by a sintering and forming method, provides more additive options for the preparation of the target material, and does not only rely on the addition of rare earth elements. The initial resistance value of the thin film resistor prepared by the sputtering target is ≥2 kΩ, and the resistance temperature coefficient is ≤±10 ppm / °C. Compared with the thin film resistor in the related technology, the stability of the thin film resistor prepared by the present invention is improved by more than 50%, and it has the advantages of high stability and high resistance value. Description of the Drawings

[0033] 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 the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0034] Figure 1 The flowchart of the preparation method of the sputtering target for the thin film resistor provided by the present invention is shown. Specific embodiments

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior art features falls within the protection scope of the present invention. And all other embodiments obtained by those of ordinary skill in the art without creative efforts also belong to the protection scope of the present invention.

[0036] If the specific experimental steps or conditions are not specified in the embodiments, the operations or conditions of the conventional experimental steps described in the prior art in the field can be carried out. The reagents and other instruments not indicating the manufacturer can be conventional reagent products obtained through commercial purchase. In addition, the drawings are only schematic diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings represent the same or similar parts, and thus their repeated description will be omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0037] For technologies, methods, and devices known to those of ordinary skill in the relevant field, detailed discussions may not be made, but in appropriate cases, the said technologies, methods, and devices should be regarded as part of the specification of the present invention.

[0038] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] A thin film resistor is a resistive element made of thin film materials. It is usually made by covering a very thin metal or alloy film on an insulating substrate, and is used to control current, voltage, signal adjustment or prevent overcurrent. It has the characteristics of high power consumption per unit area, good stability, low noise, wide frequency response range, etc., and is widely used in precision electronic equipment, instruments, communication equipment, medical equipment and other occasions.

[0040] Sputtering targets are usually used in thin film deposition technology. By bombarding with high-energy ions, atoms or molecules on the surface of the target are sputtered out and deposited on the surface of the substrate to form a thin film. Among them, high-resistance targets have a relatively high resistivity and are usually used to manufacture thin film materials with specific resistance characteristics, and have important applications in the fields of preparing sensors, precision circuits, thin film resistors, etc.

[0041] The performance of thin film resistors mainly depends on the film layer material and the film forming process. Magnetron sputtering technology has long been widely used in resistor film forming production, and has great advantages in terms of resistance value stability and output. However, the composition ratio and preparation method of the target restrict the stability and reliability of thin film resistors. Most of the high-resistance sputtering targets currently produced are produced by vacuum induction melting method. For example, in CN1415779A, a corundum-graphite-magnesite composite vacuum induction furnace is used to prepare high-resistance targets. The surface of the target is smooth, flat, without cracks on the outside and pores on the inside. The initial resistance value of the thin film resistor sputtered is 100Ω~20kΩ, and the resistance temperature coefficient is less than 30ppm / ℃. The target products produced by this method are prone to segregation, uneven composition, and generally large grains, resulting in a relatively high resistance temperature coefficient of the thin film resistor sputtered; in order to achieve a high resistance value, a relatively high content of Si and Cr is added, resulting in difficult cooling and smelting processing of the target and low yield. In CN106244988, a vacuum hot pressing sintering method is used to prepare high-resistance targets, overcoming the problems of high brittleness and easy cracking of the target caused by high Si content; by adding Al and Zr as grain refiners, a structure with an average grain size of 20~25µm is obtained; and by adding rare earth elements, the segregation of Zr elements in the alloy structure is reduced, and the composition uniformity of the target is improved. The literature "Research on Preparation and Coating Performance of Rare Earth Doped NiCrSi High-Resistance Targets" mentions that the resistance temperature coefficient of the thin film resistor sputtered by this target is <±25ppm / ℃; however, the initial resistance value of the corresponding thin film resistor is not reflected in this literature, and rare earth elements must be added to reduce the segregation of Zr elements, so as to reduce the resistance temperature coefficient to within ±25ppm / ℃.

[0042] In view of this, on the one hand, the present invention provides a preparation method of a sputtering target for thin film resistors. Figure 1 The flow chart of the preparation method of the sputtering target for thin film resistors provided by the present invention is shown, as Figure 1 shown, the preparation method specifically includes the following steps:

[0043] S1. Using Si, Cr, Ni, Al, additives and optional oxides as raw materials, preparing the raw materials into intermediate powder by alloy melting and gas atomization;

[0044] S2. Weighing a certain amount of the intermediate powder, loading it into a graphite mold, and sintering it into a target blank;

[0045] S3. Performing surface polishing treatment on the target blank and machining it to obtain a target material according to the target size;

[0046] Calculated by mass fraction, the addition amount of Si is 30 - 60 wt%, the addition amount of Cr is 20 - 40 wt%, the addition amount of Ni is 15 - 30 wt%, the addition amount of Al is 2 - 8 wt%, the addition amount of the additive is 0.1 - 5 wt%, and the addition amount of the oxide is 0 - 12.5 wt%;

[0047] The additive is selected from one or more of Mo, Ti and rare earth elements;

[0048] The oxide is selected from one or more of CuO, MoO2, RuO2, SiO2 and V2O5.

[0049] The preparation method of the sputtering target for thin - film resistors provided by the present invention improves the grain size and strength by adding appropriate additives to Si, Cr, Ni, Al, improves the resistivity and adjusts the temperature coefficient of resistance by adding appropriate oxides. The intermediate powder with uniform particle size is prepared by alloy melting and gas atomization, and then the sputtering target with high density, uniform composition distribution and fine grain size is prepared by sintering. It provides more choices of additives for the preparation of the target and does not only rely on the addition of rare earth elements. The initial resistance value of the thin - film resistor prepared by the sputtering target is ≥2 kΩ, and the temperature coefficient of resistance is ≤±10 ppm / ℃. Compared with the thin - film resistors in related technologies, the stability of the thin - film resistor prepared by the present invention is improved by more than 50%, having the advantages of high stability and high resistance value.

[0050] In some embodiments, when the raw materials contain oxides, preparing the raw materials into intermediate powder by alloy melting and gas atomization includes: performing alloying treatment on Si, Cr, Ni, Al and additives by a vacuum induction furnace to form an alloyed melt, and then using high - pressure Ar as the atomizing gas to prepare the melt into alloy powder; mixing the alloy powder with oxide powder to obtain the intermediate powder; the temperature of the alloying treatment is 1200 - 1700℃; the pressure of the atomizing gas is 1.5 - 10 MPa.

[0051] In the specific implementation of this embodiment, the raw materials contain oxides, that is, the raw materials are Si, Cr, Ni, Al, additives and oxides, and the addition amount of the oxides is 1-12.5 wt%. First, Si, Cr, Ni, Al and additives are subjected to alloying treatment using a vacuum induction furnace with Ar as the atomizing gas. The reason why Si, Cr, Ni, Al and additives are not melted together with the oxides in the vacuum induction furnace is as follows: on the one hand, induction melting relies on electromagnetic induction heating and requires materials to have good electrical conductivity, while oxides are usually insulators and it is difficult to melt them by induction heating; on the other hand, in a vacuum state, some oxides may undergo decomposition or reduction reactions. Therefore, in the specific implementation, the alloy powder is first obtained by alloy melting gas atomization treatment of Si, Cr, Ni, Al and additives, and then the alloy powder is mixed with the oxide powder to obtain the intermediate powder.

[0052] In this embodiment, the raw materials of Si, Cr, Ni, Al and additives are melted using a vacuum induction furnace to form a melt. The electromagnetic force during the vacuum induction furnace melting process has a certain stirring effect on the melt, which can refine the grains in the alloy liquid. The electromagnetic stirring makes the alloy liquid flow, breaking the growing grains and making them into more crystal nuclei, so that a finer grain structure can be obtained after solidification. The fine grain structure usually can improve the comprehensive mechanical properties such as the strength, toughness and plasticity of the alloy, making the alloy powder perform better in the subsequent processing and use processes. The combined action of electromagnetic stirring and vacuum environment helps to reduce element segregation and make the microstructure and composition of the alloy powder more uniform.

[0053] In this embodiment, the temperature of the alloying treatment is 1200-1700 °C, and it can be specifically set to 1200 °C, 1250 °C, 1300 °C... 1700 °C. When the temperature of the alloying treatment is greater than 1700 °C, the excessive temperature makes the superheat degree of the alloy liquid large, the nucleation rate is low and the growth rate is fast during cooling, and it is easy to form a coarse grain structure; when the temperature of the alloying treatment is less than 1200 °C, the low temperature makes the nucleation rate high but the atomic diffusion ability is weak, and it may form small but uneven grains. The pressure of the atomizing gas is 1.5-10 MPa, and it can be specifically set to 1.5 MPa, 2.0 MPa, 2.5 MPa... 10 MPa. When the pressure of the atomizing gas is less than 1.5 MPa, the too small pressure will result in poor atomization effect, low powder production efficiency, too large powder particle size and irregular shape, etc. When the pressure of the atomizing gas is greater than 10 MPa, the too high pressure will cause too small powder particle size, abnormal powder shape and increased equipment wear, etc. Therefore, a suitable temperature can make the organizational structure of the alloy uniform and obtain fine and uniform grains. A suitable atomizing gas pressure can obtain alloy powder with appropriate and uniform particle size and improve the powder production efficiency.

[0054] In some embodiments, when mixing alloy powder and oxide powder, three-dimensional mixing method or vibration mixing method can be adopted.

[0055] During specific implementation, the alloy powder obtained by subjecting Si, Cr, Ni, Al and additives to alloying treatment using a vacuum induction furnace and the oxide powder are sequentially added into the barrel of a three-dimensional mixer according to the ratio. After loading is completed, the barrel is sealed well to ensure that the materials will not leak during the mixing process. Then the three-dimensional mixer is started, and the barrel begins to perform complex three-dimensional motions, including self-rotation, revolution and swing. During the motion process, the materials continuously tumble, translate and rotate in the barrel, so as to achieve full mixing.

[0056] During specific implementation, the alloy powder obtained by subjecting Si, Cr, Ni, Al and additives to alloying treatment using a vacuum induction furnace and the oxide powder are sequentially added into the hopper of a vibration mixer according to the ratio. The hopper is fixed on the workbench of the vibration mixer to ensure that the hopper will not displace during the vibration process. Then the vibration mixer is started, and the hopper begins to perform high-frequency vibration under the action of the vibration source. During the vibration process, the materials continuously tumble and collide in the hopper to achieve mixing. These two mixing methods can make the alloy powder and the oxide powder reach a highly uniform distribution state in the whole mixing system.

[0057] During specific implementation, high-energy ball milling method can also be adopted for mixing. High-energy ball milling method is also called mechanochemistry. First, the alloy powder obtained by subjecting Si, Cr, Ni, Al and additives to alloying treatment using a vacuum induction furnace and the single-element powder corresponding to the oxide are mixed. For example, if the oxide to be used in this embodiment is CuO, the alloy powder and Cu powder can be loaded into the ball milling tank of a high-energy ball mill according to the ratio, appropriate grinding balls are introduced, and the ball-to-material ratio can be 5:1 - 20:1. An atmosphere is introduced into the ball milling tank, and the atmosphere is a mixed atmosphere of an inert gas (such as argon) and oxygen. During the ball milling process, the grinding balls continuously collide, extrude and rub against the single-element powder. On the one hand, this mechanical force action continuously refines the single-element powder, increases its specific surface area and improves the reaction activity; on the other hand, it also provides energy for the contact and reaction between the element and oxygen. As the ball milling progresses, the surface of the single-element powder gradually undergoes a chemical reaction with oxygen and begins to form an oxide, thereby realizing the addition of the oxide in the raw material components.

[0058] In some embodiments, when the raw material does not contain an oxide, preparing the raw material into an intermediate powder by alloy melting and gas atomization method includes: subjecting Si, Cr, Ni, Al and additives to alloying treatment using a vacuum induction furnace to form an alloyed melt, and then using high-pressure Ar as the atomizing gas to prepare the melt into the intermediate powder; the temperature of the alloying treatment is 1200 - 1700 °C; the pressure of the atomizing gas is 1.5 - 10 MPa.

[0059] In the specific implementation of this embodiment, the raw materials do not contain oxides, that is, the raw materials are only Si, Cr, Ni, Al, and additives, and the addition amount of oxides is 0. Si, Cr, Ni, Al, and additives are alloyed by a vacuum induction furnace, and Ar is introduced as the atomizing gas, and intermediate powder can be directly obtained.

[0060] In this embodiment, different types of metal raw materials are mixed and melted by a vacuum induction furnace to ensure the consistency and stability of the alloy properties. The electromagnetic stirring effect during the melting process of the vacuum induction furnace can refine the grains in the alloy liquid. The combined action of electromagnetic stirring and the vacuum environment helps to reduce element segregation and make the microstructure and composition of the alloy powder more uniform. Appropriate temperature can homogenize the organizational structure of the alloy and obtain fine and uniform grains. Appropriate atomizing gas pressure can obtain alloy powder with appropriate and uniform particle size, improving the powder production efficiency.

[0061] In some embodiments, the particle size of the intermediate powder is 10 - 60 µm.

[0062] In this embodiment, the particle size of the powder obtained by the above preparation method is 10 - 60 µm, which can be 10 µm, 15 µm, 20 µm... 60 µm. When the particle size of the powder is less than 10 µm, the particle size is too fine, and during the forming process, the friction between particles is large and the fluidity becomes poor. In order to obtain a green body with a certain density, a greater pressure needs to be applied. The powder with an appropriate particle size has good fluidity and packing property, can be filled more evenly in the graphite mold, and the required forming pressure is relatively low, reducing the pressure requirement and energy consumption of the equipment. In addition, when the particle size of the powder is in the range of 10 - 60 µm, the powder can be packed in a relatively compact manner, reducing the porosity in the green body, which is beneficial to obtaining a high-density target during the sintering process.

[0063] In some embodiments, in step S2, the sintering and forming is carried out by vacuum hot pressing sintering, and the vacuum hot pressing sintering is carried out under the protection of Ar, the vacuum degree is lower than 500 Pa, the temperature is 1000 - 1250 °C, and the pressure is 15 - 60 MPa.

[0064] In specific implementation, a quantitative amount of intermediate powder is weighed and evenly loaded into a graphite mold. The mold containing the powder is placed into the furnace chamber of a vacuum hot-pressing sintering furnace. The vacuum system is started to pump out the air in the furnace chamber, and Ar is introduced to make the vacuum degree in the furnace reach a predetermined value, i.e., less than 500 Pa, so as to reduce the influence of impurities and gases on the sintering process and prevent the powder from oxidizing. According to a preset heating curve, for example, the sintering temperature is set to 1100 °C, and the heating system is started to gradually increase the temperature in the furnace. When the temperature reaches a certain value, the pressure system is started to apply pressure to the mold, for example, set to 20 MPa. When the temperature and pressure reach the set values, they are maintained for a period of time for heat preservation and pressure holding to achieve the gradual densification of the target. After the heat preservation and pressure holding are completed, the heating is stopped, and the temperature in the furnace is allowed to gradually decrease. The cooling method can be natural cooling or forced cooling. When the temperature drops to a certain extent, the pressure is slowly removed to avoid cracks in the target due to too rapid pressure change. In this embodiment, vacuum hot-pressing sintering is used, and the temperature is set in the range of 1000 - 1250 °C, which helps the diffusion of elements in the target and makes the composition more uniform. The pressure is set in the range of 15 - 60 MPa, which can promote the densification of the target and the refinement of grains.

[0065] In some embodiments, in step S2, the sintering and forming is carried out by spark plasma sintering. The vacuum degree of the spark plasma sintering is 20 - 100 Pa, the sintering temperature is 900 - 1100 °C, and the pressure is 5 - 20 MPa.

[0066] In specific implementation, the intermediate powder is evenly loaded into a graphite mold. The mold containing the powder is placed into the sintering chamber of a spark plasma sintering device, ensuring that the mold is placed stably and in good contact with components such as electrodes. Components such as a pressure sensor and heating electrodes are connected well to ensure that the device can accurately apply pressure and transmit current. The vacuum system is started to pump out the air in the sintering chamber to make the vacuum degree less than 100 Pa, and the power supply is turned on to apply a pulsed current to the mold. When the pulsed current passes through the mold and the powder, Joule heat is generated, causing the powder to rapidly heat up. When the set sintering temperature is reached, for example, 900 °C, it is maintained for a period of time for heat preservation to fully sinter and densify the powder.

[0067] In this embodiment, spark plasma sintering is used. The temperature is set in the range of 900 - 1100 °C, which helps the diffusion of elements in the target and makes the composition more uniform. The pressure is set in the range of 5 - 20 MPa, which can promote the densification of the target and the refinement of grains.

[0068] In the second aspect, the present invention provides a sputtering target for a thin-film resistor, which is obtained according to the above preparation method; the density of the sputtering target obtained by the above method is ≥ 95%.

[0069] The present invention provides a sputtering target with high density, uniform composition distribution, and fine grain size of the target.

[0070] In a third aspect, the present invention provides an application of a sputtering target for a thin film resistor, and the sputtering target is used as a sputtering target for a thin film resistor.

[0071] In specific implementation, the above-mentioned target is used to deposit a resistive film on an 0805 type alumina substrate, the sputtering power is 120 W, Ar:N = 50:0 sccm, and the air pressure is 0.5 Pa.

[0072] The thin film resistor provided by the present invention improves the grain size and strength by adding appropriate additives to Si, Cr, Ni, and Al, improves the resistivity and adjusts the resistance temperature coefficient by adding appropriate oxides, prepares intermediate powder with uniform particle size by alloy melting and gas atomization method, and then uses spark plasma sintering method and vacuum hot pressing sintering method to sinter and form a sputtering target with high density, uniform composition distribution, and fine grain size, providing more additive options for the preparation of the target, not only relying on the addition of rare earth elements. The initial resistance value of the thin film resistor prepared by the sputtering target is ≥2 kΩ, and the resistance temperature coefficient is ≤±10 ppm / °C. Compared with the thin film resistor in the related technology, the stability of the thin film resistor prepared by the present invention is improved by more than 50%, having the advantages of high stability and high resistance value.

[0073] To make those skilled in the art understand the present application more clearly, the following examples are now used to detail a sputtering target for a thin film resistor, a preparation method thereof, and an application thereof described in the present application.

[0074] Example 1

[0075] Using Si, Cr, Ni, Al, and additives as raw materials, and the additives are Ti and Y. Prepare the raw materials according to the following ratio. By mass fraction, the addition amount of Si is 47.5 wt%, the addition amount of Cr is 28.9 wt%, the addition amount of Ni is 18.1 wt%, the addition amount of Al is 3.5 wt%, the addition amount of Ti is 1.8 wt%, and the addition amount of Y is 0.2 wt%.

[0076] Load the above raw materials into the crucible of a vacuum induction furnace for alloying treatment. First, start the vacuum system. When the vacuum degree in the furnace reaches the requirement, start the induction heating system. The temperature for alloying treatment is 1450 °C to melt the raw materials into a melt; when the raw materials are completely melted, use Ar as the atomizing gas with a pressure of 3 MPa, and atomize the alloy melt into fine droplets through a nozzle; the droplets are rapidly cooled and solidified into powder in the high-pressure gas; the atomized powder is collected by a collecting device, and after collection, it is screened to obtain intermediate powder with an average particle size of 35 µm.

[0077] Weigh an appropriate amount of intermediate powder and load it into a graphite mold. Using the spark plasma sintering method, with a vacuum degree of about 50 Pa, set the sintering temperature at 900 °C and the pressure at 8 MPa for sintering and forming to obtain a target blank.

[0078] Dry grind the above target blank to make a target with the target size.

[0079] The density of the target obtained by the above preparation method is 96.5%, and the volume resistivity is 1865.4 μΩ·cm. Using this target to deposit a resistive film on an alumina substrate of model 0805, with a sputtering power of 120 W, Ar:N = 50:0 sccm, and a gas pressure of 0.5 Pa, a thin film resistor is obtained. The initial resistance value of the thin film resistor is 2.2 kΩ, and the resistance temperature coefficient is -8.72 ppm / °C.

[0080] In Example 1, by adding appropriate additives to Si, Cr, Ni, and Al to improve the grain size and strength, a sputtering target with high density, uniform composition distribution, and fine grain size is prepared by the spark plasma sintering method. The initial resistance value of the thin film resistor obtained by the sputtering target is ≥2 kΩ, and the resistance temperature coefficient is ≤±10 ppm / °C. Compared with the thin film resistors in the related technologies, the stability of the thin film resistor prepared in this example is increased by more than 50%, having the advantages of high stability and high resistance value.

[0081] Example 2

[0082] Using Si, Cr, Ni, Al, additives, and oxides as raw materials, the additive is Ti, and the oxide is SiO2. Prepare the raw materials according to the following ratio. By mass fraction, the addition amount of Si is 37.0 wt%, the addition amount of Cr is 24.6 wt%, the addition amount of Ni is 21.9 wt%, the addition amount of Al is 4.2 wt%, the addition amount of Ti is 2.3 wt%, and the addition amount of SiO2 is 10 wt%.

[0083] Load the raw materials of Si, Cr, Ni, Al, and Ti into the crucible of a vacuum induction furnace for alloying treatment. First, start the vacuum system. When the vacuum degree in the furnace reaches the requirement, start the induction heating system. The temperature for alloying treatment is 1450 °C to melt the raw materials into a melt; when the raw materials are completely melted, use Ar as the atomizing gas with a pressure of 5 MPa, and atomize the alloy melt into fine droplets through a nozzle; the droplets are rapidly cooled and solidified into powder in the high-pressure gas; the atomized powder is collected by a collection device, and after collection, it is screened to obtain alloy powder with an average particle size of 25 μm. Add the SiO2 powder and the alloy powder together into a three-dimensional mixer according to the above ratio to obtain intermediate powder.

[0084] Weigh an appropriate amount of intermediate powder and load it into a graphite mold. Using the spark plasma sintering method, with a vacuum degree of about 30 Pa, set the sintering temperature at 1000 °C and the pressure at 15 MPa for sintering and forming to obtain a target blank.

[0085] Dry grind the above target blank to make a target with the target size.

[0086] The density of the target obtained by the above preparation method is 97.6%, and the volume resistivity is 2879.1 μΩ·cm. Using the same method for preparing a thin film resistor as in Example 1, a thin film resistor is obtained. The initial resistance value of the thin film resistor is 6.8 kΩ, and the resistance temperature coefficient is -7.6 ppm / °C.

[0087] In this example, by adding appropriate additives to Si, Cr, Ni, and Al, the grain size and strength are improved. By adding appropriate oxides, the resistivity and the resistance temperature coefficient are adjusted. Using the spark plasma sintering method, a sputtering target with high density, uniform composition distribution, and fine grain size is prepared, providing more additive choices for the preparation of the target and not relying only on the addition of rare earth elements. The initial resistance value of the thin film resistor prepared by the sputtering target is ≥2 kΩ, and the resistance temperature coefficient is ≤±10 ppm / °C. Compared with the thin film resistor in the related technology, the stability of the thin film resistor prepared by the present invention is increased by more than 50%, having the advantages of high stability and high resistance value.

[0088] Example 3

[0089] Using Si, Cr, Ni, Al, additives, and oxides as raw materials, the additive is Mo, and the oxides are CuO and SiO2. Prepare the raw materials according to the following ratio. By mass fraction, the addition amount of Si is 39.9 wt%, the addition amount of Cr is 24.6 wt%, the addition amount of Ni is 21.9 wt%, the addition amount of Al is 5.1 wt%, the addition amount of Mo is 1.3 wt%, the addition amount of CuO is 0.8 wt%, and the addition amount of SiO2 is 6.4 wt%.

[0090] Load the raw materials of Si, Cr, Ni, Al, and Mo into the crucible of a vacuum induction furnace for alloying treatment. First, start the vacuum system. When the vacuum degree in the furnace reaches the requirement, start the induction heating system. The temperature for alloying treatment is 1600 °C to melt the raw materials into a melt. When the raw materials are completely melted, use Ar as the atomizing gas with a pressure of 5 MPa, and atomize the alloy melt into fine droplets through a nozzle. The droplets are quickly cooled and solidified into powder in the high-pressure gas. The atomized powder is collected by a collection device, and after collection, it is screened to obtain an alloy powder with an average particle size of 25 μm. Add the CuO powder and SiO2 powder to the alloy powder together into a three-dimensional mixer according to the above ratio to obtain an intermediate powder.

[0091] Weigh an appropriate amount of intermediate powder and load it into a graphite mold. Using the spark plasma sintering method, with a vacuum degree of about 30 Pa, set the sintering temperature at 950 °C and the pressure at 9 MPa for sintering and forming to obtain a target blank.

[0092] Dry grind the above target blank to make a target with the desired size.

[0093] The target obtained by the above preparation method has a relative density of 98.5% and a volume resistivity of 3263.9 μΩ·cm. Using the same method for preparing thin-film resistors as in Example 1, a thin-film resistor is obtained. The initial resistance value of the thin-film resistor is 5.4 kΩ, and the temperature coefficient of resistance is -6.5 ppm / °C.

[0094] Example 4

[0095] Using Si, Cr, Ni, Al, and additives as raw materials, where the additives are Ti and Y. The raw material ratio and implementation steps for preparing the intermediate powder are the same as in Example 1. The only difference is that an appropriate amount of intermediate powder is weighed and loaded into a graphite mold, and the vacuum hot pressing sintering method is used. The vacuum degree is about 400 Pa, the sintering temperature is set at 1100 °C, and the pressure is 45 MPa for sintering and forming to obtain a target blank.

[0096] The size of the target obtained by the above preparation method is 559x127x13 mm, the relative density is 97.1%, and the volume resistivity is 1763.2 μΩ·cm. Using the same method for preparing thin-film resistors as in Example 1, a thin-film resistor is obtained. The initial resistance value of the thin-film resistor is 2.4 kΩ, and the temperature coefficient of resistance is -8.51 ppm / °C.

[0097] Example 5

[0098] Using Si, Cr, Ni, Al, additives, and oxides as raw materials, where the additive is Mo and the oxides are MoO2 and SiO2. Prepare the raw materials according to the following ratio. By mass fraction, the addition amount of Si is 37.6 wt%, the addition amount of Cr is 25.1 wt%, the addition amount of Ni is 24.0 wt%, the addition amount of Al is 4.9 wt%, the addition amount of Mo is 1.3 wt%, the addition amount of MoO2 is 0.9 wt%, and the addition amount of SiO2 is 6.2 wt%.

[0099] Load the mixed raw materials of Si, Cr, Ni, Al, and Mo into the crucible of a vacuum induction furnace for alloying treatment. The temperature of the alloying treatment is 1580 °C, and the atomization pressure is 5 MPa. The remaining steps are the same as in Example 3 to obtain alloy powder with an average particle size of 25 μm. Add the MoO2 powder and SiO2 powder to the alloy powder in the vibration mixer according to the above ratio to obtain the intermediate powder.

[0100] Weigh an appropriate amount of the intermediate powder and place it into a graphite mold. Using the spark plasma sintering method, with a vacuum degree of approximately 100 Pa, set the sintering temperature to 900 °C and the pressure to 11 MPa for sintering and forming to obtain a target blank.

[0101] Dry grind the above target blank to make a target material with the target size.

[0102] The target material obtained by the above preparation method has a relative density of 95.7% and a volume resistivity of 3024.7 μΩ·cm. Using the same method for preparing a thin film resistor as in Example 1, a thin film resistor is obtained. The initial resistance value of the thin film resistor is 4.3 kΩ, and the resistance temperature coefficient is -6.2 ppm / °C.

[0103] Example 6

[0104] Using Si, Cr, Ni, Al, an additive, and an oxide as raw materials, the additive is Ti, and the oxides are RuO2 and V2O5. Prepare the raw materials according to the following ratio. By mass fraction, the addition amount of Si is 42.3 wt%, the addition amount of Cr is 21.6 wt%, the addition amount of Ni is 18.9 wt%, the addition amount of Al is 4.2 wt%, the addition amount of Ti is 2.3 wt%, the addition amount of RuO2 is 6.5 wt%, and the addition amount of V2O5 is 4.2 wt%.

[0105] Load the raw materials of Si, Cr, Ni, Al, and Ti into the crucible of a vacuum induction furnace for alloying treatment. The temperature of the alloying treatment is 1580 °C, and the pressure of the atomizing gas is 5 MPa. The remaining steps are the same as in Example 3 to obtain alloy powder with an average particle size of 25 μm. Add the RuO2 powder and V2O5 powder to the alloy powder together according to the above ratio into a three-dimensional mixer to obtain an intermediate powder.

[0106] Weigh an appropriate amount of the intermediate powder and place it into a graphite mold. Using the spark plasma sintering method, with a vacuum degree of approximately 100 Pa, set the sintering temperature to 900 °C and the pressure to 10 MPa for sintering and forming to obtain a target blank.

[0107] Dry grind the above target blank to make a target material with the target size.

[0108] The target material obtained by the above preparation method has a relative density of 95.5% and a volume resistivity of 3963.9 μΩ·cm. Using the same method for preparing a thin film resistor as in Example 1, a thin film resistor is obtained. The initial resistance value of the thin film resistor is 6.6 kΩ, and the resistance temperature coefficient is -8.9 ppm / °C.

[0109] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0110] For method embodiments, for the sake of simple description, they are all expressed as a series of combinations of actions. However, those skilled in the art should know that the present invention is not limited by the described order of actions, because according to the present invention, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0111] The above has introduced in detail a sputtering target for a thin film resistor, a preparation method thereof, and its application. Specific examples are used herein to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for preparing a sputtering target for a thin film resistor, characterized in that: The preparation method specifically comprises the following steps: S1. Using Si, Cr, Ni, Al, additives and optional oxides as raw materials, the raw materials are prepared into intermediate powder by alloy melting gas atomization; S2, weighing a certain amount of the intermediate powder, loading it into a graphite mold, sintering it to obtain a target blank; S3, performing surface polishing treatment on the target blank, and processing the target target material according to the target size; In terms of mass fraction, the amount of Si added is 30-60wt%, the amount of Cr added is 20-40wt%, the amount of Ni added is 15-30wt%, the amount of Al added is 2-8wt%, the amount of additives added is 0.1-5wt%, and the amount of oxide added is 0-12.5wt%; The additive is selected from one or more of Mo, Ti and rare earth elements; The oxide is selected from one or more of CuO, MoO2, RuO2, SiO2 and V2O5; In step S2, the sintering molding adopts spark plasma sintering, the vacuum degree of the spark plasma sintering is 20~100Pa, the sintering temperature is 900~1100℃, and the pressure is 5~20MPa.

2. The preparation method according to claim 1, characterized in that: When the raw material contains oxides, the process of preparing the raw material into an intermediate powder by alloy smelting and gas atomization includes: Alloying Si, Cr, Ni, Al and additives in a vacuum induction furnace to form an alloyed melt, and then using high-pressure Ar as an atomizing gas to prepare the melt into an alloy powder; Mixing the alloy powder and the oxide powder to obtain the intermediate powder; The temperature of the alloying treatment is 1200-1700°C; The pressure of the atomizing gas is 1.5-10 MPa.

3. The preparation method according to claim 2, characterized in that: The alloy powder and the oxide powder are mixed by a three-dimensional mixing method or a vibration mixing method.

4. The preparation method according to claim 1, characterized in that: When the raw material does not contain oxides, the method of preparing the raw material into an intermediate powder by alloy smelting gas atomization includes: Alloying Si, Cr, Ni, Al and additives in a vacuum induction furnace to form an alloyed melt, and then using high-pressure Ar as an atomizing gas to prepare the melt into the intermediate powder; The temperature of the alloying treatment is 1200-1700°C; The pressure of the atomizing gas is 1.5-10 MPa.

5. The preparation method according to claim 1, characterized in that: The particle size of the intermediate powder is 10-60 μm.

6. The preparation method according to claim 1, characterized in that: In step S2, the sintering molding adopts vacuum hot pressing sintering, and the vacuum hot pressing sintering is carried out under Ar protection conditions, with a vacuum degree lower than 500 Pa, a temperature of 1000-1250° C., and a pressure of 15-60 MPa.

7. A sputtering target material for a thin film resistor, characterized in that: The sputtering target is obtained by the preparation method according to any one of claims 1 to 6; The density of the sputtering target is ≥95%.

8. An application of the sputtering target material for the thin film resistor according to claim 7, characterized in that: The sputtering target is used as a sputtering target material for a thin film resistor.

Images