Preparation method of tungsten-silicon alloy target material

Abstract

The invention relates to a preparation method of a tungsten-silicon alloy target material, in particular to the field of target material preparation.The preparation method comprises the steps that tungsten powder and silicon powder are mixed and then formed, and a green body is obtained; the blank is sequentially subjected to cold isostatic pressing and pressureless sintering, and the tungsten-silicon alloy target material is obtained; the pressureless sintering comprises heating, heat preservation and cooling which are carried out in sequence; the heating rate of the heating is greater than or equal to 20 DEG C / min. According to the preparation method provided by the invention, the preparation of the tungsten-silicon target material with smaller silicon grains is realized by designing the preparation process of the tungsten-silicon target material, forming, carrying out cold isostatic pressing treatment and then matching with pressureless sintering with high-speed heating, so that the obtained tungsten-silicon target material is ensured to have good use performance during sputtering operation.

Description

Technical Field

[0001] The present invention relates to the field of target material preparation, and in particular to a method for preparing a tungsten-silicon alloy target material. Background Art

[0002] Tungsten silicon alloy thin films have good electrical conductivity, high temperature resistance, corrosion resistance and other properties, and are widely used in semiconductor integrated circuits. Their main preparation processes include physical vapor deposition and chemical vapor deposition. For example, sputtering coating technology is used to prepare the film layer. The role of the target material is particularly important during sputtering coating, and its performance will significantly affect the performance of the resulting film. The preparation process of the tungsten silicon alloy target material will significantly affect the performance of the resulting target material.

[0003] Currently, the target material preparation process of tungsten silicon alloy is to mix W powder and Si powder and then sinter them. For example, CN103056368A discloses a method for preparing tungsten silicon alloy target material. The present invention includes the following steps:

[0004] (1) Thoroughly mixing tungsten powder, silicon powder and a forming agent to obtain tungsten-silicon alloy powder; (2) cold-pressing the tungsten-silicon alloy powder obtained in step (1) to obtain a preform; (3) vacuum hot-pressing the preform obtained in step (2) to obtain a sintered blank after cooling; (4) cutting the sintered blank obtained in step (3) to obtain a tungsten-silicon alloy target.

[0005] For example, CN116356265A discloses a method for preparing a large-sized fine-grained tungsten silicon target material, which includes the following steps: 1. Mixing high-purity tungsten powder and silicon powder to obtain a mixed powder; 2. Placing the mixed powder in a hot pressing furnace and hot pressing and sintering it in multiple process stages to obtain a tungsten silicon prefabricated target blank; 3. Using a hot isostatic pressing device to hot isostatically press the tungsten silicon prefabricated target blank to obtain a large-sized fine-grained tungsten silicon target material.

[0006] However, the above preparation method may cause abnormal growth of silicon grains during the preparation process, resulting in uneven distribution of target grain size, causing material dropout during sputtering or poor thickness uniformity of the film obtained by sputtering. Summary of the Invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for preparing a tungsten-silicon alloy target material to solve the problem that silicon grains grow abnormally during the preparation process, resulting in the defect that the silicon grains of the target material are too large.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for preparing a tungsten-silicon alloy target, the preparation method comprising:

[0010] The tungsten powder and silicon powder are mixed and then formed to obtain a green body;

[0011] The green body is sequentially subjected to cold isostatic pressing and pressureless sintering to obtain a tungsten-silicon alloy target;

[0012] The pressureless sintering includes heating, holding and cooling in sequence;

[0013] The heating rate of the heating is ≥20°C / min.

[0014] The preparation method provided by the present invention realizes the preparation of tungsten silicon target material with smaller silicon grains through the design of the tungsten silicon target material preparation process, through molding, cold isostatic pressing treatment, and high-speed temperature rising pressureless sintering, thereby ensuring that the obtained tungsten silicon target material has good performance when performing sputtering operations.

[0015] As a preferred technical solution of the present invention, the D50 particle size of the tungsten powder is 8-10 μm.

[0016] Preferably, the D50 particle size of the silicon powder is 6-8 μm.

[0017] As a preferred technical solution of the present invention, the mass percentage of silicon powder in the mixed powder obtained by mixing is 28-30%.

[0018] As a preferred technical solution of the present invention, the forming method includes: compression molding.

[0019] Preferably, the compression molding pressure is 50-70t.

[0020] Preferably, the compression molding time is ≥5 min.

[0021] As a preferred technical solution of the present invention, the holding pressure of the cold isostatic pressing is ≥100 MPa.

[0022] Preferably, the pressing rate of the cold isostatic pressing is 1-3 MPa / min.

[0023] Preferably, the holding time of the cold isostatic pressing is 20-40 minutes.

[0024] Preferably, after the cold isostatic pressing is completed, the pressure is released at a pressure reduction rate of 3-5 MPa / min.

[0025] As a preferred technical solution of the present invention, the end point temperature of the heating is the insulation temperature of the insulation.

[0026] As a preferred technical solution of the present invention, the insulation temperature is 1400-1450°C.

[0027] As a preferred technical solution of the present invention, the heat preservation time is 0.8-1.5h.

[0028] As a preferred technical solution of the present invention, the cooling rate is 4-7°C / min.

[0029] As a preferred technical solution of the present invention, the end point of the cooling is a temperature ≤ 40°C.

[0030] Compared with the existing technical solutions, the present invention has the following beneficial effects:

[0031] The preparation method provided by the present invention optimizes the preparation process of the tungsten silicon target material, performs specific molding and cold isostatic pressing treatments, and then significantly limits the growth rate of silicon grains in the absence of pressure during sintering in combination with high-speed heating. The method can significantly reduce the size of silicon grains in the obtained tungsten silicon target material, so that the gap between WSi2 grains and silicon grains in the obtained target material is smaller, thereby obtaining a high-performance target material, solving the problem of abnormal growth of silicon grains during the preparation of the tungsten silicon target material, which makes the silicon grains too large and leads to poor grain size uniformity of the obtained tungsten silicon target material. The average diameter of silicon grains in the obtained tungsten silicon target material product is ≤17.1μm, and the average diameter of WSi2 grains is ≤9.0μm.

[0032] The present invention is further described in detail below. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0033] To better illustrate the present invention and facilitate understanding of the technical solutions of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0034] At present, when preparing tungsten silicon targets, it is found that silicon grains will grow abnormally, and their growth rate is significantly higher than the growth rate of WSi2 grains, resulting in poor uniformity of the grain size of the obtained tungsten silicon target, which in turn affects the uniformity of the film layer obtained by sputtering coating, which is not conducive to achieving efficient coating. Based on this, the present invention optimizes the preparation process of tungsten silicon targets. During sintering, the growth rate of silicon grains is significantly limited by high-speed temperature increase under no pressure, so that the silicon grains in the obtained target are significantly reduced, thereby obtaining a high-performance target, as follows:

[0035] This embodiment provides a method for preparing a tungsten-silicon alloy target, comprising:

[0036] The tungsten powder and silicon powder are mixed and then formed to obtain a green body;

[0037] The green body is sequentially subjected to cold isostatic pressing and pressureless sintering to obtain a tungsten-silicon alloy target;

[0038] The pressureless sintering includes heating, keeping warm and cooling down in sequence.

[0039] The D50 particle size of the tungsten powder is 8-10 μm, for example, it can be 8 μm, 8.2 μm, 8.4 μm, 8.6 μm, 8.8 μm, 9 μm, 9.2 μm, 9.4 μm, 9.6 μm, 9.8 μm or 10 μm, but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0040] The D50 particle size of the silicon powder is 6-8 μm, for example, it can be 6 μm, 6.2 μm, 6.4 μm, 6.6 μm, 6.8 μm, 7 μm, 7.2 μm, 7.4 μm, 7.6 μm, 7.8 μm or 8 μm, but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0041] The mass percentage of silicon powder in the mixed powder obtained by mixing is 28-30%, for example, it can be 28%, 28.2%, 28.4%, 28.6%, 28.8%, 29%, 29.2%, 29.4%, 29.6%, 29.8% or 30%, etc., but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0042] Wherein, the forming method includes: compression molding.

[0043] Among them, the molding pressure is 50-70t, for example, it can be 50t, 52t, 54t, 56t, 58t, 60t, 62t, 64t, 66t, 68t or 70t, etc., but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0044] The compression molding time is ≥5 min, for example, it can be 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, etc., but is not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0045] The holding pressure of the cold isostatic pressing is ≥100 MPa, for example, it can be 100 MPa, 120 MPa, 140 MPa, 160 MPa, 180 MPa, 200 MPa, 220 MPa, 240 MPa, 260 MPa, 280 MPa or 300 MPa, but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0046] The pressurization rate of the cold isostatic pressing is 1-3 MPa / min, for example, it can be 1 MPa / min, 1.2 MPa / min, 1.4 MPa / min, 1.6 MPa / min, 1.8 MPa / min, 2 MPa / min, 2.2 MPa / min, 2.4 MPa / min, 2.6 MPa / min, 2.8 MPa / min or 3 MPa / min, but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0047] Among them, the holding time of the cold isostatic pressing is 20-40min, for example, it can be 20min, 22min, 24min, 26min, 28min, 30min, 32min, 34min, 36min, 38min or 40min, but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0048] Among them, after the cold isostatic pressing is completed, the pressure is released at a pressure reduction rate of 3-5 MPa / min, for example, it can be 3 MPa / min, 3.2 MPa / min, 3.4 MPa / min, 3.6 MPa / min, 3.8 MPa / min, 4 MPa / min, 4.2 MPa / min, 4.4 MPa / min, 4.6 MPa / min, 4.8 MPa / min or 5 MPa / min, but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0049] In the present invention, after cold isostatic pressing, the pressure is released to zero so as to proceed to the next step.

[0050] The heating rate of the heating is ≥20°C / min, for example, it can be 20°C / min, 22°C / min, 24°C / min, 26°C / min, 28°C / min, 30°C / min, 32°C / min, 34°C / min, 36°C / min, 38°C / min or 40°C / min, but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0051] Wherein, the end temperature of the heating is the insulation temperature of the insulation.

[0052] Among them, the insulation temperature is 1400-1450℃, for example, it can be 1400℃, 1405℃, 1410℃, 1415℃, 1420℃, 1425℃, 1430℃, 1435℃, 1440℃, 1445℃ or 1450℃, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0053] The insulation time is 0.8-1.5h, for example, it can be 0.8h, 0.85h, 0.9h, 0.95h, 1h, 1.05h, 1.1h, 1.15h, 1.2h, 1.25h, 1.3h, 1.35h, 1.4h, 1.45h or 1.5h, etc., but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0054] Wherein, the cooling rate is 4-7°C / min, for example, it can be 4°C / min, 4.2°C / min, 4.4°C / min, 4.6°C / min, 4.8°C / min, 5°C / min, 5.2°C / min, 5.4°C / min, 5.6°C / min, 5.8°C / min, 6°C / min, 6.2°C / min, 6.4°C / min, 6.6°C / min, 6.8°C / min or 7°C / min, etc., but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0055] The end point of the cooling is a temperature ≤ 40°C, for example, it can be 40°C, 35°C, 30°C, 25°C, 20°C, 15°C, 10°C or 5°C, but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0056] Furthermore, in order to illustrate the good use effect that can be achieved by the tungsten-silicon alloy target obtained by the preparation method provided by the present invention, the following actual example is used for illustration:

[0057] Example 1

[0058] This embodiment provides a method for preparing a tungsten-silicon alloy target, which is specifically as follows:

[0059] The tungsten powder and silicon powder are mixed and then formed to obtain a green body;

[0060] The green body is sequentially subjected to cold isostatic pressing and pressureless sintering to obtain a tungsten-silicon alloy target;

[0061] The pressureless sintering includes heating, keeping warm and cooling down in sequence.

[0062] The D50 particle size of the tungsten powder used is 9 μm, the D50 particle size of the silicon powder is 7 μm, and the mass percentage of the silicon powder in the mixed powder obtained by mixing is 29%;

[0063] The molding method is compression molding, the pressure is 60t, and the time is 5min;

[0064] The holding pressure of the cold isostatic pressing is 100 MPa, the pressurization rate is 2 MPa / min, the holding time is 30 min, and after the holding time is completed, the pressure is released to 0 MPa at a pressure reduction rate of 4 MPa / min;

[0065] The heating rate of the heating is 20°C / min, and the end temperature of the heating is the holding temperature of the insulation; the holding temperature of the insulation is 1425°C, and the insulation time is 1h; the cooling rate of the cooling is 6°C / min, and the end temperature is 20°C.

[0066] Example 2

[0067] This embodiment provides a method for preparing a tungsten-silicon alloy target, which is specifically as follows:

[0068] The tungsten powder and silicon powder are mixed and then formed to obtain a green body;

[0069] The green body is sequentially subjected to cold isostatic pressing and pressureless sintering to obtain a tungsten-silicon alloy target;

[0070] The pressureless sintering includes heating, keeping warm and cooling down in sequence.

[0071] The D50 particle size of the tungsten powder used is 8 μm, the D50 particle size of the silicon powder is 8 μm, and the mass percentage of the silicon powder in the mixed powder obtained by mixing is 28.5%;

[0072] The molding method is compression molding, the pressure is 65t, and the time is 5min;

[0073] The holding pressure of the cold isostatic pressing is 150 MPa, the pressurization rate is 2.5 MPa / min, the holding time is 25 min, and after the holding time is completed, the pressure is released to 0 MPa at a pressure reduction rate of 4.5 MPa / min;

[0074] The heating rate of the heating is 25°C / min, and the end temperature of the heating is the holding temperature of the insulation; the holding temperature of the insulation is 1430°C, and the insulation time is 1.2h; the cooling rate of the cooling is 5°C / min, and the end temperature is 10°C.

[0075] Example 3

[0076] This embodiment provides a method for preparing a tungsten-silicon alloy target, which is specifically as follows:

[0077] The tungsten powder and silicon powder are mixed and then formed to obtain a green body;

[0078] The green body is sequentially subjected to cold isostatic pressing and pressureless sintering to obtain a tungsten-silicon alloy target;

[0079] The pressureless sintering includes heating, keeping warm and cooling down in sequence.

[0080] The D50 particle size of the tungsten powder used is 8 μm, the D50 particle size of the silicon powder is 6 μm, and the mass percentage of the silicon powder in the mixed powder obtained is 30%;

[0081] The molding method is compression molding, the pressure is 50t, and the time is 8min;

[0082] The holding pressure of the cold isostatic pressing is 200 MPa, the pressurization rate is 1 MPa / min, the holding time is 20 min, and after the holding time is completed, the pressure is released to 0 MPa at a pressure reduction rate of 3 MPa / min;

[0083] The heating rate of the heating is 40°C / min, and the end point temperature of the heating is the holding temperature of the insulation; the holding temperature of the insulation is 1400°C, and the insulation time is 0.5h; the cooling rate of the cooling is 7°C / min, and the end point temperature is 10°C.

[0084] Example 4

[0085] This embodiment provides a method for preparing a tungsten-silicon alloy target, which is specifically as follows:

[0086] The tungsten powder and silicon powder are mixed and then formed to obtain a green body;

[0087] The green body is sequentially subjected to cold isostatic pressing and pressureless sintering to obtain a tungsten-silicon alloy target;

[0088] The pressureless sintering includes heating, keeping warm and cooling down in sequence.

[0089] The D50 particle size of the tungsten powder used is 10 μm, the D50 particle size of the silicon powder is 8 μm, and the mass percentage of the silicon powder in the mixed powder obtained by mixing is 28%;

[0090] The molding method is compression molding, the pressure is 70t, and the time is 10min;

[0091] The holding pressure of the cold isostatic pressing is 180 MPa, the pressurization rate is 3 MPa / min, the holding time is 40 min, and after the holding time is completed, the pressure is released to 0 MPa at a pressure reduction rate of 5 MPa / min;

[0092] The heating rate of the heating is 20°C / min, and the end temperature of the heating is the holding temperature of the insulation; the holding temperature of the insulation is 1450°C, and the insulation time is 0.8h; the cooling rate of the cooling is 4°C / min, and the end temperature is 25°C.

[0093] Comparative Example 1

[0094] The only difference from Example 1 is that no compression molding is performed.

[0095] Comparative Example 2

[0096] The only difference from Example 1 is that no cold isostatic pressing was performed.

[0097] Comparative Example 3

[0098] The only difference from Example 1 is that the heating rate is 15° C. / min.

[0099] Comparative Example 4

[0100] The only difference from Example 1 is that the heating rate is 10° C. / min.

[0101] Comparative Example 5

[0102] The only difference from Example 1 is that the heating rate is 5° C. / min.

[0103] Comparative Example 6

[0104] The only difference from Example 1 is that a pressure of 150 MPa is applied during pressureless sintering, that is, pressureless sintering is converted into hot isostatic pressing sintering.

[0105] Example 5

[0106] The only difference from Example 1 is that the holding temperature is 1300°C.

[0107] Example 6

[0108] The only difference from Example 1 is that the holding temperature is 1550°C.

[0109] The tungsten-silicon alloy targets obtained in the above examples and comparative examples were subjected to grain inspection and analysis according to the standard ASTM E112-13-2021. The results are shown in Table 1 below.

[0110] Table 1

[0111]

[0112]

[0113] As can be seen from Table 1, the preparation method provided by the present invention realizes the preparation of tungsten silicon target materials with smaller silicon grains through the design of the tungsten silicon target material preparation process, through molding, cold isostatic pressing treatment, and high-speed temperature rise pressureless sintering, thereby ensuring that the obtained tungsten silicon target material has good performance during sputtering operation.

[0114] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0115] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0116] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a tungsten-silicon alloy target, characterized in that: The preparation method comprises: The tungsten powder and silicon powder are mixed and then formed to obtain a green body; The green body is sequentially subjected to cold isostatic pressing and pressureless sintering to obtain a tungsten-silicon alloy target; The pressureless sintering includes heating, holding and cooling in sequence; The heating rate of the heating is ≥20°C / min.

2. The preparation method according to claim 1, wherein The D50 particle size of the tungsten powder is 8-10 μm; Preferably, the D50 particle size of the silicon powder is 6-8 μm.

3. The preparation method according to claim 1, wherein The mass percentage of silicon powder in the mixed powder obtained by mixing is 28-30%.

4. The preparation method according to claim 1, wherein The forming methods include: compression molding; Preferably, the compression molding pressure is 50-70t; Preferably, the compression molding time is ≥5 min.

5. The preparation method according to claim 1, wherein The holding pressure of the cold isostatic pressing is ≥100 MPa; Preferably, the pressurization rate of the cold isostatic pressing is 1-3 MPa / min; Preferably, the holding time of the cold isostatic pressing is 20-40 minutes; Preferably, after the cold isostatic pressing is completed, the pressure is released at a pressure reduction rate of 3-5 MPa / min.

6. The preparation method according to claim 1, wherein The end point temperature of the heating is the insulation temperature of the insulation.

7. The preparation method according to claim 1, wherein The heat preservation temperature is 1400-1450°C.

8. The preparation method according to claim 1, wherein The heat preservation time is 0.8-1.5h.

9. The preparation method according to claim 1, wherein The cooling rate is 4-7°C / min.

10. The preparation method according to claim 1, wherein The end point of the cooling is a temperature ≤ 40°C.

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