High-purity tungsten-silicon composite powder and preparation method thereof

Abstract

The application discloses a high-purity tungsten-silicon composite powder and a preparation method thereof. The preparation method of the embodiment comprises the following steps: mixing high-purity tungsten oxide powder and purified SiHCl3 solution to obtain a mixture; and performing hydrogen heating reduction on the mixture to obtain the high-purity tungsten-silicon composite powder. The high-purity tungsten-silicon composite powder prepared by the application has the advantages of uniform element distribution and extremely high purity, and a high-purity tungsten-silicon alloy target material with uniform element distribution and few internal structure defects can be prepared by using the composite powder as raw material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of processing of raw materials of semiconductor sputtering target material powder, and particularly relates to a high-purity tungsten-silicon composite powder and a preparation method thereof. BACKGROUND

[0002] The phenomenon that atoms of a target material are knocked out by high-speed ion bombardment on the surface of the target material is called sputtering, and the process that the atoms generated by sputtering are successively deposited on a base surface to form a thin film is called sputtering film deposition. Sputtering film deposition is an extremely important process for preparing semiconductor film layers.

[0003] The tungsten-silicon alloy target material has the characteristics of high electrical conductivity, stable contact performance with silicon material, and good high-temperature stability, and is mainly used as a target material for semiconductor sputtering film deposition. The film formed by sputtering of the tungsten-silicon target material is an excellent conductor material and is widely used in the fields of semiconductor integrated circuit gate materials and electronic thin films. Research shows that the higher the purity of the tungsten-silicon alloy, the more uniform the distribution of tungsten and silicon elements, and the lower the oxygen content, the smaller the resistance of the sputtered thin film, and the better the stability of the film layer, which is conducive to improving the overall quality of the film.

[0004] Chinese patent document CN110714185A discloses a preparation method of a tungsten-silicon target material. Polycrystalline silicon particles with a purity of ≥6N are used as raw materials instead of silicon powder, and a tungsten-silicon mixture is prepared by adopting a ball milling process for mixing and crushing. Then, the tungsten-silicon alloy is prepared by cold pressing and vacuum hot pressing sintering. Compared with high-purity silicon powder, the purity of the polycrystalline silicon particles is easier to control, and the powder mixing and polycrystalline silicon crushing are combined in one step, thereby improving the production efficiency.

[0005] Chinese patent document CN113981387A discloses a preparation method of a tungsten-silicon target material. First, tungsten powder with a purity of 99.999% or above and silicon powder with a purity of 99.999% or above are placed in a mold, vacuum heating treatment is performed to form a tungsten-silicon alloy, the tungsten-silicon alloy is crushed for the first and second times to prepare tungsten-silicon alloy powder, and then the tungsten-silicon alloy powder is placed in a mold and vacuum heating treatment is performed to form a tungsten-silicon target material.

[0006] Chinese patent document CN114293158A discloses a preparation method of a tungsten-silicon alloy target material. Silicon powder and tungsten powder are used as raw materials. The silicon powder is vacuum heated to 800-1000℃, then water-quenched, and then vacuum dried after vacuum ball milling in a ball milling tank. The vacuum-dried silicon powder is ultrasonically treated in a mixed solution of sulfuric acid and hydrochloric acid, then washed with water, and then vacuum dried in a drying box. Then, the silicon powder and the tungsten powder are vacuum ball milled. The tungsten-silicon powder is vacuum induction heated to obtain a preliminary alloyed tungsten-silicon powder, which is ball milled and crushed to prepare a tungsten-silicon mixed powder. Finally, the tungsten-silicon mixed powder is sintered, machined, and the carburized layer is removed to obtain a tungsten-silicon alloy target material.

[0007] It is known from the literature that tungsten-silicon alloy target material has very important applications in the field of semiconductor integrated circuit gate material and electronic film, and with the continuous improvement of the purity and element uniformity of the target material, the stability of the sputtered film is better, and the performance of the semiconductor circuit is continuously improved. However, the existing preparation method still generally uses high-purity tungsten powder and high-purity silicon powder for solid-solid mixing, and then molding and sintering to prepare tungsten-silicon alloy, which has the defects of low element distribution uniformity and difficult control of purity, so it is necessary to further improve the preparation method of tungsten-silicon alloy target powder raw material. SUMMARY

[0008] The main purpose of the present application is to provide a high-purity tungsten-silicon composite powder and a preparation method thereof, so as to promote the uniform distribution of tungsten and silicon elements in the composite powder and its alloy, and improve the purity of the composite powder, thereby providing support for enhancing the performance of tungsten-silicon alloy target material.

[0009] In order to achieve the above-mentioned main purpose, the first aspect of the present application discloses a preparation method of high-purity tungsten-silicon composite powder, comprising the following steps:

[0010] Mixing high-purity tungsten oxide powder and purified SiHCl3 solution to obtain a mixture;

[0011] Hydrogen heating reduction of the mixture to obtain high-purity tungsten-silicon composite powder.

[0012] The present application uses high-purity tungsten oxide powder and purified SiHCl3 solution as raw materials, and the purity of the prepared tungsten-silicon composite powder can reach 99.9% or more (99.9-99.9999%). In the heating reduction process, SiHCl3 can be vaporized and exist in liquid and gaseous states in turn, which can realize liquid-solid mixing and gas-solid mixing with tungsten oxide powder, so that the distribution of tungsten and silicon elements is more uniform. Subsequently, the tungsten oxide is reduced to tungsten particles with controllable particle size; SiHCl3 reacts with H to form elemental silicon and adhere to the surface of tungsten particles, forming a core-shell structure of tungsten particles uniformly coated with silicon elements, reducing the contact probability between tungsten particles, so that the tungsten grains in the sintered tungsten-silicon alloy are small and uniform. In addition, the silicon elements adhered to the surface of the tungsten particles are also easy to react with tungsten to form WSi2, at this time, in addition to the uniform mixing of tungsten and silicon elements in the early stage, mutual diffusion also occurs, further improving the element distribution uniformity.

[0013] According to a specific embodiment of the present application, the temperature of hydrogen heating reduction is 1100-1250℃.

[0014] Preferably, the heating rate of hydrogen heating reduction is 3-10℃ / min, and the holding time is 30-90min.

[0015] In the present application, the particle size of tungsten particles can be controlled by adjusting the hydrogen reduction process, such as reduction temperature, heating rate, holding time, etc., to obtain high-purity tungsten-silicon composite powder with different particle sizes. The purity of hydrogen is preferably 99.9995% or more.

[0016] In the present application, the tungsten oxide can be any one or more of WO3, WO 2.9 , WO 2.72 and WO2. Preferably, the purity of tungsten oxide is 99.9995% or more.

[0017] In the present application, the impurity content in the purified SiHCl3 solution is preferably less than 1x10 -10 wt%.

[0018] In the present application, the SiHCl3 solution can be prepared by the following method:

[0019] The industrial silicon powder is placed in a synthesis furnace and dry HCl gas is introduced for heating reaction to generate a mixed gas containing SiHCl3 and HCl;

[0020] The mixed gas is cooled to below 20℃ to condense SiHCl3 gas to obtain SiHCl3 solution;

[0021] The SiHCl3 solution is subjected to rectification purification.

[0022] In the above technical solution, industrial silicon powder is used as the source of silicon element, which has the advantages of wide source and low price, and can greatly reduce the production cost of high-purity tungsten-silicon powder. There is no special requirement for the particle size and silicon element mass percentage of the industrial silicon powder raw material, and high-purity SiHCl3 solution can be prepared. Preferably, the particle size of the industrial silicon powder is less than 1mm.

[0023] In order to achieve the above-mentioned main purpose, the second aspect of the present application provides a high-purity tungsten-silicon composite powder, which is prepared by mixing high-purity tungsten oxide powder and purified SiHCl3 solution, and then heating and reducing the mixture with hydrogen; wherein the mass of silicon element accounts for 5-35% of the total mass of tungsten-silicon composite powder.

[0024] As mentioned above, the mixture of high-purity tungsten oxide powder and SiHCl3 solution is heated and reduced with hydrogen to obtain high-purity tungsten-silicon composite powder, which forms a core-shell structure with tungsten as the core and silicon as the shell, and the tungsten and silicon elements are uniformly distributed in the composite powder, which is especially suitable for the preparation of high-purity tungsten-silicon alloy target material.

[0025] In order to more clearly illustrate the technical solutions, purposes and advantages of the present application, the present application will be further described in detail below with specific examples. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 Microscopic morphology of high purity tungsten-silicon composite powder prepared in Example 1;

[0027] Figure 2 Phase result of high purity tungsten-silicon composite powder prepared in Example 1. DETAILED DESCRIPTION

[0028] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the present application can be practiced without the specific details, and that the following examples and detailed description are for illustrative purposes only and not intended to limit the scope of the present application.

[0029] Example 1

[0030] The preparation method of Example 1 includes the following steps:

[0031] (1) Preparation and purification of SiHCl3 solution

[0032] An industrial silicon powder with a purity of 99.9% and an average particle size of 0.10 mm was placed in a synthesis furnace, dry HCl gas was continuously introduced, and the temperature was raised to 250°C at a rate of 5°C / min, with a reaction time of 60 min, to generate a mixed gas containing SiHCl3 and HCl.

[0033] A water cooling device was provided at the gas outlet of the synthesis furnace to cool the mixed gas to a temperature of 20°C, and the cooled SiHCl3 solution was collected, followed by a rectification purification process to remove impurity elements such as iron, aluminum, and copper, to obtain a SiHCl3 solution with a purity of 99.9999%. The rectification purification process is a commonly used purification technology, which mainly utilizes the characteristic that different chlorides have different boiling points to separate the preliminarily prepared SiHCl3 solution. After rectification and purification, the impurity content of the SiHCl3 solution can be less than 1 x 10 -10 wt%.

[0034] (2) Mixing and reduction of tungsten oxide powder and SiHCl3 solution

[0035] WO3 powder with a purity of 99.9999% was added to the purified SiHCl3 solution, and the mixing ratio of WO3 powder and SiHCl3 solution was controlled such that the mass of silicon element accounted for 29% of the total mass of tungsten-silicon composite powder.

[0036] The mixture was placed in a high-pressure reaction container, and then high-purity H2 with a purity of 99.9999% was introduced and the high-pressure reaction container was sealed.

[0037] Put the high-pressure reaction container into the rotary furnace, set the reduction heating rate to 5°C / min, and directly raise the temperature to 1150°C, with a holding time of 60 min, to obtain high-purity tungsten-silicon composite powder.

[0038] Example 2

[0039] (1) Preparation and purification of SiHCl3 solution

[0040] Put industrial silicon powder with a purity of 99.9% and an average particle size of 0.10 mm into the synthesis furnace, continuously pass dry HCl gas, and heat to 250°C at a heating rate of 5°C / min, with a reaction time of 60 min, to generate a mixed gas containing SiHCl3 and HCl.

[0041] Set a water cooling device at the gas outlet of the synthesis furnace to cool the mixed gas to a temperature of 20°C, collect the cooled SiHCl3 solution, and then remove impurity elements such as iron, aluminum, and copper using a rectification purification process to obtain SiHCl3 solution with a purity of 99.9999%.

[0042] (2) Mixing and reduction of tungsten oxide powder and SiHCl3 solution

[0043] Add WO 2.9 powder with a purity of 99.9999% to the purified SiHCl3 solution, and control the mixing ratio of the WO 2.9 powder and the SiHCl3 solution to be 29% of the total mass of the tungsten-silicon composite powder in terms of silicon element mass.

[0044] Put the mixture into a high-pressure reaction container, and then pass high-purity H2 with a purity of 99.9999% into the high-pressure reaction container and seal it.

[0045] Put the high-pressure reaction container into the rotary furnace, set the reduction heating rate to 5°C / min, first raise the temperature to 1000°C and hold for 60 min, and then raise the temperature to 1150°C and hold for 60 min.

[0046] Under the staged reduction process of Example 2, the tungsten oxide is first reduced to tungsten at 1000°C, and SiHCl3 reacts with H to form elemental silicon and adhere to the surface of the tungsten particles at 1150°C. The tungsten particle size grows during the reduction of elemental silicon, and high-purity tungsten-silicon composite powder with a larger tungsten particle size is obtained.

[0047] Example 3

[0048] (1) Preparation and purification of SiHCl3 solution

[0049] The method is the same as in Example 1, except that the average particle size of the industrial silicon powder used is 0.5 mm and the purity is 99.5%, and SiHCl3 solution with a purity of 99.9999% is prepared.

[0050] (2) Mixing and reduction of tungsten oxide powder and SiHCl3 solution

[0051] WO3 powder with purity of 99.9999% and WO2 powder with purity of 99.9999% were added into the purified SiHCl3 solution, the mixing ratio of WO3 powder and WO2 powder to SiHCl3 solution was controlled according to the mass of silicon element accounting for 25% of the total mass of tungsten-silicon composite powder, and the WO3 powder and WO2 powder were proportioned according to the mass ratio of tungsten element 1:1. 2.9 and WO2 2.72 powder were added into the purified SiHCl3 solution, the mixing ratio of WO3 powder and WO2 powder to SiHCl3 solution was controlled according to the mass of silicon element accounting for 20% of the total mass of tungsten-silicon composite powder, and the WO3 powder and WO2 powder were proportioned according to the mass ratio of tungsten element 1:1. 2.9 , WO3 2.72 powder and SiHCl3 solution was controlled according to the mass of silicon element accounting for 25% of the total mass of tungsten-silicon composite powder, and the WO3 powder and WO2 powder were proportioned according to the mass ratio of tungsten element 1:1. 2.9 , WO3 2.72 powder was proportioned according to the mass ratio of tungsten element 1:1.

[0052] The mixture was placed in a high-pressure reaction container, then high-purity H2 with purity of 99.9999% was passed through, and the high-pressure reaction container was sealed.

[0053] The high-pressure reaction container was placed in a rotary furnace, the reduction temperature was set to 1180°C, the reduction temperature rising rate was set to 10°C / min, and the holding time was 60 min, to obtain high-purity tungsten-silicon composite powder.

[0054] Example 4

[0055] (1) Preparation and purification of SiHCl3 solution

[0056] The method was the same as that in Example 3, and SiHCl3 solution with purity of 99.9999% was prepared.

[0057] (2) Mixing and reduction of tungsten oxide powder and SiHCl3 solution

[0058] WO3 powder with purity of 99.9999% and WO2 powder with purity of 99.9999% were added into the purified SiHCl3 solution, the mixing ratio of WO3 powder and WO2 powder to SiHCl3 solution was controlled according to the mass of silicon element accounting for 25% of the total mass of tungsten-silicon composite powder, and the WO3 powder and WO2 powder were proportioned according to the mass ratio of tungsten element 1:1. 2.72 and WO2 2.72 powder were added into the purified SiHCl3 solution, the mixing ratio of WO3 powder and WO2 powder to SiHCl3 solution was controlled according to the mass of silicon element accounting for 20% of the total mass of tungsten-silicon composite powder, and the WO3 powder and WO2 powder were proportioned according to the mass ratio of tungsten element 1:1. 2.72 , WO3 2.72 powder was proportioned according to the mass ratio of tungsten element 1:1.

[0059] The mixture was placed in a high-pressure reaction container, then high-purity H2 with purity of 99.9999% was passed through, and the high-pressure reaction container was sealed.

[0060] The high-pressure reaction container was placed in a rotary furnace, the reduction temperature was set to 1200°C, the reduction temperature rising rate was set to 10°C / min, and the holding time was 50 min, to obtain high-purity tungsten-silicon composite powder.

[0061] Figure 1Fig. 1 is a micrograph of the high-purity tungsten-silicon composite powder prepared in Example 1, and it can be seen from the figure that the silicon particles are uniformly coated on the surface of the tungsten particles, and the average particle size of the tungsten-silicon composite powder is about 1.0 μm.

[0062] Figure 2 Fig. 2 is a phase result (XRD) diagram of the high-purity tungsten-silicon composite powder prepared in Example 1, and the result shows that the composite powder is composed of two phases of WSi2 and Si, and has no other impurity phase, thus having the advantage of high purity.

[0063] Although the present application is disclosed with specific embodiments as above, it should be understood that the specific embodiments described above are not intended to limit the scope of the present application. Any person skilled in the art can make some improvements without departing from the scope of the present application, and any equivalent improvements made according to the present application should be covered by the scope of the present application. Therefore, the scope of the present application should be defined by the claims.

Claims

1. A method for preparing high-purity tungsten-silicon composite powder, comprising the following steps: Mixing high-purity tungsten oxide powder and purified SiHCl3 solution to obtain a mixture; wherein, The purity of the tungsten oxide is above 99.9995%, and the mixing ratio of the tungsten oxide powder and the SiHCl3 solution is controlled to be 5-35% of the total mass of the tungsten-silicon composite powder in terms of silicon element mass; The mixture is subjected to hydrogen heating reduction to obtain high-purity tungsten-silicon composite powder with a purity above 99.9%; wherein the temperature of the hydrogen heating reduction is 1100-1250°C, the heating rate is 3-10°C / min, and the holding time is 30-90 min; The SiHCl3 solution is obtained by the following method: Industrial silicon powder is placed in a synthesis furnace, dry HCl gas is introduced for heating reaction to generate SiHCl3 and HCl mixed gas; wherein the temperature of the heating reaction is controlled to be 250-300°C, and the reaction time is 30-90 min; The mixed gas is cooled to below 20°C to condense SiHCl3 gas to obtain SiHCl3 solution; The SiHCl3 solution is subjected to rectification purification.

2. The method of claim 1; wherein, WO3, WO 2.9 , WO 2.72 , and WO2.

3. The method of manufacturing according to claim 1; wherein, The impurity content in the purified SiHCl3 solution is less than 1 x 10 -10 wt%.

4. The high purity tungsten-silicon composite powder prepared by the method of claim 1, wherein the high purity tungsten oxide powder and the purified SiHCl3 solution are mixed first, and then the mixture is subjected to hydrogen heating reduction at a temperature of 1100-1250°C. The purity of the tungsten-silicon composite powder is above 99.9%, and the purity of the tungsten oxide is above 99.9995%.

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