Device and method for directional solidification of silicon-molybdenum alloy for sputter target

Abstract

The application discloses a device and method for preparing silicon-molybdenum alloy for sputtering target by directional solidification, which comprises a directional solidification furnace, a protective gas inlet arranged at the bottom of the directional solidification furnace, and a protective gas outlet arranged at the top of the directional solidification furnace; a ceramic crucible is arranged in the directional solidification furnace, a graphite crucible is arranged in the ceramic crucible, and a heat preservation layer is arranged between the ceramic crucible and the graphite crucible; a thermocouple is arranged at the bottom of the graphite crucible, and an infrared temperature measuring instrument is arranged above the graphite crucible in the directional solidification furnace; a water cooling mechanism is arranged at the bottom of the ceramic crucible; an induction coil is arranged outside the ceramic crucible in the directional solidification furnace, and the induction coil is connected with a moving mechanism, and the moving mechanism drives the induction coil to move up and down. The silicon-molybdenum alloy is prepared by the casting method, the preparation of the silicon-molybdenum target material is rapid and uniform, the solidification related parameters and the purity of raw materials are controlled, the compactness of the silicon-molybdenum alloy is improved, the oxygen content is effectively reduced, and the preparation of the silicon-molybdenum alloy for the high-performance sputtering target material is realized.

Description

Technical Field

[0001] This invention relates to the field of silicon-molybdenum alloy preparation technology, and specifically to an apparatus and method for directional solidification preparation of silicon-molybdenum alloy for sputtering targets. Background Technology

[0002] Silicon-molybdenum alloy sputtering targets are used in vacuum sputtering coating. Currently, the mainstream preparation method for silicon-molybdenum alloy sputtering targets is powder metallurgy, which involves mixing powders, densifying them, and then preparing them in a high-temperature, high-pressure sealed hot isostatic pressing furnace. However, products prepared by this method have defects such as low density, low purity (3-4N), and high oxygen content, which seriously restricts the application of the products. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an apparatus and method for directional solidification preparation of silicon-molybdenum alloy for sputtering targets. While improving the density of silicon-molybdenum alloy, it can also reduce its oxygen content. Moreover, due to the high purity of the raw materials, the purity of the prepared alloy is also high. At the same time, the present invention can effectively improve the production efficiency of molybdenum-silicon targets by using a casting method, and finally realizes the efficient and homogeneous preparation of silicon-molybdenum alloy for high-performance sputtering targets.

[0004] The technical solution of this invention is as follows:

[0005] In a first aspect, the present invention provides an apparatus for directional solidification of silicon-molybdenum alloy for sputtering targets, comprising a directional solidification furnace, wherein a protective gas inlet is provided at the bottom of the directional solidification furnace and a protective gas outlet is provided at the top; a ceramic crucible is provided inside the directional solidification furnace, a graphite crucible is provided inside the ceramic crucible, and a heat insulation layer is provided between the ceramic crucible and the graphite crucible; a thermocouple is provided at the bottom of the graphite crucible, and an infrared thermometer is provided above the graphite crucible inside the directional solidification furnace; a water cooling mechanism is provided at the bottom of the ceramic crucible; an induction coil is provided outside the ceramic crucible inside the directional solidification furnace, and the induction coil is connected to a moving mechanism, which drives the induction coil to move up and down.

[0006] Preferably, the moving mechanism is a stepper motor.

[0007] Preferably, the insulation layer is made of carbon felt.

[0008] Preferably, the water cooling mechanism includes a hollow heat exchange block disposed at the bottom of the ceramic crucible, and cooling water pipes are laid inside the heat exchange block.

[0009] Preferably, the thermocouple is a tungsten-rhenium thermocouple.

[0010] In a second aspect, the present invention provides a method for preparing silicon-molybdenum alloy for sputtering targets by directional solidification using the above-mentioned apparatus, comprising the following steps:

[0011] S1 adds silicon and molybdenum materials into a graphite crucible, introduces protective gas into the directional solidification furnace, and simultaneously starts the water cooling mechanism;

[0012] S2 supplies a high-frequency current (30kHz-80kHz) to the induction coil, inductively heating the graphite crucible to raise the temperature of the raw material inside to 1420℃, ensuring complete melting. When the upper and lower temperatures of the melt, detected by both the infrared thermometer and the thermocouple, reach 1420℃ and remain stable for a period, it indicates complete melting of the raw material. During this process, the frequency and magnitude of the induction current are controlled to maintain a stable melt temperature, ensuring complete alloying within the melt. In this invention, two temperature measurement methods are performed in parallel: the infrared thermometer is located at the top of the directional solidification furnace to directly measure the surface temperature of the melt, while the thermocouple is placed at the bottom of the graphite crucible to measure the temperature at the bottom of the crucible (approximately equivalent to the bottom temperature of the melt). These two methods operate synchronously, facilitating control of the heating process and the internal temperature gradient of the melt.

[0013] After the S3 raw material is completely melted, the induction coil is moved upward by the moving mechanism, so that the melt in the graphite crucible forms a temperature gradient from top to bottom, which promotes the spontaneous directional solidification of the melt inside the graphite crucible. When the temperature measured by the infrared thermometer and thermocouple is 10°C below the melting point and is maintained for 10 minutes, the melt is considered to have completely solidified, and the silicon-molybdenum alloy is obtained at this time.

[0014] The directional solidification of this invention refers to the directional growth of grains by controlling the temperature gradient inside the melt. This method has two advantages: First, the controllability of crystal growth is better, because the crystal growth rate during the directional solidification process is affected by the temperature gradient, and the overall growth behavior is controllable. Second, by controlling the temperature gradient, the distribution of elements can be relatively controlled, and the element ratio at different locations can be controlled to the maximum extent, thereby obtaining a uniform silicon-molybdenum sputtering target.

[0015] Preferably, in step S1, the mass ratio of molybdenum material to silicon material is 0.01-0.07:1.

[0016] Preferably, in step S1, the protective gas is an inert gas.

[0017] In order to achieve stable directional solidification of the melt, two conditions need to be met: first, the temperature at the bottom of the melt needs to be below the melting point of the melt itself; second, the temperature gradient inside the melt needs to be relatively low and controllable so as to control the stable growth of the crystal. Therefore, preferably, in step S3, the temperature gradient of the melt needs to be controlled at 2-6℃ / mm.

[0018] Preferably, in step S1, before adding the raw material to the graphite crucible, the inside of the graphite crucible is air-washed using a high-pressure air gun to ensure that there is no floating powder inside.

[0019] The method for preparing target materials using the silicon-molybdenum alloy prepared by this invention is as follows:

[0020] (1) After the directional solidification furnace cools to room temperature, the silicon molybdenum ingot is removed. Diamond wire cutting technology is used to remove the sides, bottom, and top of the ingot, reducing the impact of grain growth, crucible contamination, and difficulty in uniformly controlling elements at the top of the crucible, which could lead to non-compliance with pre-set requirements. Diamond wire cutting technology is an existing technology, and its specific operation is as follows: First, the ingot to be cut is stabilized on the cutting platform, and the parameters of the cutting machine are adjusted, such as the tension, rotation speed, and feed rate of the diamond wire. The diamond wire is controlled to slowly descend into the ingot, reciprocating to allow it to slowly enter the ingot. After a period of cutting, the diamond wire gradually penetrates the ingot and cuts it into the desired shape along the pre-set trajectory. During this period, it is necessary to maintain a stable feed rate and cutting depth to ensure cutting quality. After cutting is completed, the diamond wire is slowly lifted to remove it from the ingot, and then the cutting machine is stopped and the cut ingot is removed.

[0021] (2) The alloy ingot is squared and cut according to the required target size to finally realize the preparation of molybdenum-silicon alloy target.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] This invention uses high-purity silicon and high-purity molybdenum as raw materials, and utilizes induction melting and directional solidification technologies to achieve rapid melting and alloying of silicon-molybdenum alloy raw materials. By controlling relevant process parameters during directional solidification, stable precipitation and uniform distribution of the molybdenum-silicon alloy phase are achieved. Compared with silicon-molybdenum alloys prepared by traditional powder metallurgy methods, this invention improves the density of the silicon-molybdenum alloy while reducing its oxygen content. Furthermore, due to the high purity of the raw materials, the prepared alloy also has high purity. Simultaneously, this invention employs a casting method, which effectively improves the production efficiency of silicon-molybdenum alloys, ultimately achieving efficient and uniform preparation of silicon-molybdenum alloys for high-performance sputtering targets. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the apparatus for the directional solidification preparation of silicon-molybdenum alloy for sputtering targets according to the present invention.

[0026] Figure 2 This is one of the SEM images of the silicon-molybdenum alloy prepared in Example 2 of this invention.

[0027] Figure 3 This is the second SEM image of the silicon-molybdenum alloy prepared in Example 2 of this invention.

[0028] In the diagram, 1 is a directional solidification furnace; 101 is a protective gas inlet; 102 is a protective gas outlet; 2 is a ceramic crucible; 3 is a graphite crucible; 4 is an insulation layer; 5 is a thermocouple; 6 is an infrared thermometer; 7 is a water-cooling mechanism; and 8 is an induction coil. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0030] like Figure 1 As shown in the following embodiments, the apparatus for preparing silicon-molybdenum alloy for sputtering targets by directional solidification has the following specific structure: It includes a directional solidification furnace 1, with a protective gas inlet 101 at the bottom and a protective gas outlet 102 at the top; a ceramic crucible 2 is placed inside the directional solidification furnace 1, and a graphite crucible 3 is placed inside the ceramic crucible 2, with a heat insulation layer 4 (such as carbon felt) between the ceramic crucible 2 and the graphite crucible 3; a tungsten-rhenium thermocouple 5 is placed at the bottom of the graphite crucible 3, and an infrared thermometer 6 is placed above the graphite crucible 3 inside the directional solidification furnace 1; a water-cooling mechanism 7 is placed at the bottom of the ceramic crucible 2, including a hollow heat exchange block at the bottom of the ceramic crucible 2, with cooling water pipes laid inside the heat exchange block, and cooling water flowing through the cooling water pipes; an induction coil 8 is placed outside the ceramic crucible 2 inside the directional solidification furnace 1, and the induction coil 8 is connected to a moving mechanism, which uses a stepper motor to drive the induction coil 8 to move up and down. Among them, the tungsten-rhenium thermocouple 5, the infrared thermometer 6, and the motor are all electrically connected to the controller, which feeds back the melt temperature in the graphite crucible 3 to the controller in real time to realize the monitoring of the melt temperature.

[0031] Example 1

[0032] The method for preparing silicon-molybdenum alloy for sputtering targets by directional solidification in this embodiment includes the following steps:

[0033] S1 selects the appropriate high-purity molybdenum sheets and silicon material (elemental silicon) according to a mass ratio of 0.01:1, and uses a high-pressure air gun to gas-wash the inside of the graphite crucible 3 to remove residual carbon powder inside, so as to ensure the purity of the melt. The molybdenum sheets and silicon material are added to the graphite crucible 3, and argon gas is continuously introduced into the directional solidification furnace 1 at a flow rate of 2L / min, while circulating cooling water is introduced into the cooling water pipe.

[0034] S2 passes a high-frequency current of 50kHz into the induction coil 8 to induction heat the graphite crucible 3. At the same time, the infrared thermometer and thermocouple 5 are observed to ensure that the heating process is stable until the temperature rises to 1420℃. The melt temperature is maintained at 1420℃ for 30 minutes to ensure that there are no more single-phase molybdenum sheets inside the melt and that the melt is completely alloyed.

[0035] After the S3 raw material is completely melted, the induction coil 8 is moved upward by the moving mechanism, so that the melt in the graphite crucible 3 forms a temperature gradient from top to bottom (about 3℃ / mm), which promotes the spontaneous directional solidification of the melt inside the graphite crucible 3. After the melt is completely solidified, the silicon-molybdenum alloy is obtained.

[0036] Example 2

[0037] The method for preparing silicon-molybdenum alloy for sputtering targets by directional solidification in this embodiment includes the following steps:

[0038] S1 selects the appropriate high-purity molybdenum sheets and silicon materials according to a mass ratio of 0.03:1, and uses a high-pressure air gun to gas-wash the inside of the graphite crucible 3 to remove residual carbon powder inside, so as to ensure the purity of the melt. The molybdenum sheets and silicon materials are added to the graphite crucible 3, and argon gas is continuously introduced into the directional solidification furnace 1 at a flow rate of 2L / min, while circulating cooling water is introduced into the cooling water pipe.

[0039] S2 passes a high-frequency current of 50kHz into the induction coil 8 to induction heat the graphite crucible 3. At the same time, the infrared thermometer and thermocouple 5 are observed to ensure that the heating process is stable until the temperature rises to 1420℃. The melt temperature is maintained at 1420℃ for 30 minutes to ensure that there are no more single-phase molybdenum sheets inside the melt and that the melt is completely alloyed.

[0040] After the S3 raw material is completely melted, the induction coil 8 is moved upward by the moving mechanism, so that the melt in the graphite crucible 3 forms a temperature gradient from top to bottom (about 5℃ / mm), which promotes the spontaneous directional solidification of the melt inside the graphite crucible 3. After the melt is completely solidified, the silicon-molybdenum alloy is obtained.

[0041] Depend on Figure 2-3 As shown in the SEM image of the silicon-molybdenum alloy prepared in Example 2, the preparation method of the present invention achieves uniform precipitation of the silicon-molybdenum phase, and the ingot elements are relatively uniform, which can be used as a target material.

[0042] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the invention should also be covered within the protection scope of the invention. Therefore, the protection scope of the invention should be determined by the scope of the claims.

Claims

1. An apparatus for preparing silicon-molybdenum alloys for sputtering targets using directional solidification, and a method for preparing silicon-molybdenum alloys for sputtering targets using directional solidification, characterized in that, The apparatus for preparing silicon-molybdenum alloy for sputtering targets by directional solidification includes a directional solidification furnace (1), a protective gas inlet (101) at the bottom of the directional solidification furnace (1), and a protective gas outlet (102) at the top; a ceramic crucible (2) is provided inside the directional solidification furnace (1), a graphite crucible (3) is provided inside the ceramic crucible (2), and a heat insulation layer (4) is provided between the ceramic crucible (2) and the graphite crucible (3); a thermocouple (5) is provided at the bottom of the graphite crucible (3), and an infrared thermometer (6) is provided above the graphite crucible (3) inside the directional solidification furnace (1); a water cooling mechanism (7) is provided at the bottom of the ceramic crucible (2); an induction coil (8) is provided outside the ceramic crucible (2) inside the directional solidification furnace (1), and the induction coil (8) is connected to a moving mechanism, which drives the induction coil (8) to move up and down; The method for preparing silicon-molybdenum alloy for sputtering targets by directional solidification includes the following steps: S1 adds silicon and molybdenum materials into a graphite crucible (3), introduces protective gas into the directional solidification furnace (1), and simultaneously starts the water cooling mechanism (7); the mass ratio of molybdenum to silicon is 0.01-0.07:1; S2 supplies current to the induction coil (8) to heat the graphite crucible (3) by induction, raising the temperature of the raw material inside the graphite crucible (3) to 1420°C, ensuring that the raw material is completely melted; After the S3 raw material is completely melted, the induction coil (8) is moved upward by the moving mechanism, so that the melt in the graphite crucible (3) forms a temperature gradient from top to bottom, which promotes the spontaneous directional solidification of the melt inside the graphite crucible (3). After the melt is completely solidified, the silicon-molybdenum alloy is obtained; the temperature gradient of the melt is 2-6℃ / mm.

2. The method as described in claim 1, characterized in that, In step S1, an inert gas is used as the protective gas.

3. The method as described in claim 1, characterized in that, In step S1, before adding the raw material to the graphite crucible (3), the inside of the graphite crucible (3) is air-washed with a high-pressure air gun to remove any floating powder inside.

4. The method as described in claim 1, characterized in that, The moving mechanism uses a stepper motor.

5. The method as described in claim 1, characterized in that, The insulation layer (4) is made of carbon felt.

6. The method as described in claim 1, characterized in that, The water cooling mechanism (7) includes a hollow heat exchange block located at the bottom of the ceramic crucible (2), and cooling water pipes are laid inside the heat exchange block.

7. The method as described in claim 1, characterized in that, The thermocouple (5) is a tungsten-rhenium thermocouple.

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