Electrostatic chuck special conductive paste, preparation method and application thereof

Abstract

The application relates to a conductive paste special for an electrostatic chuck and a preparation method and application thereof, and the conductive paste is prepared by the following mass percentages: tungsten powder 80-85%, neodymium oxide 0.4-0.8%, aluminum oxide 1-1.5%, silicon dioxide 1-1.5%, an organic carrier 10-16% and a dispersing agent 1.5-2.8%. When the conductive paste is applied to an electrode layer in the electrostatic chuck by introducing neodymium oxide particles, the compactness of the electrode layer can be obviously improved, the square resistance is reduced, excellent conductive performance is exhibited, the electrostatic chuck has good electrostatic adsorption capacity, meanwhile, the silicon dioxide and the aluminum oxide are wetly penetrated into the inside of a ceramic base of the electrostatic chuck and form a mechanical interlocking structure with the ceramic, so that the bonding force between the electrode layer and the ceramic base is enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrostatic chuck, in particular to a special conductive slurry for electrostatic chuck, and a preparation method and application thereof. BACKGROUND

[0002] As a core component of semiconductor manufacturing equipment, the electrostatic chuck fixes the wafer in the key process such as dry etching, and has an important influence on the manufacturing precision and efficiency. Among them, the electrode layer as the core functional component directly determines the adsorption performance and electrical characteristics of the electrostatic chuck. However, there are two major problems in the prior art: firstly, the electrode layer has insufficient density, which leads to high square resistance, limits the conductive performance, and further affects the electrostatic adsorption capacity, thereby restricting the overall efficiency and reliability of the semiconductor manufacturing equipment; secondly, the electrode pattern area ratio of the ceramic electrostatic chuck is usually more than 70%, which is significantly higher than the conventional high-temperature co-fired ceramic substrate, which puts higher requirements on the bonding strength of the ceramic and the metal. Therefore, how to improve the conductive performance of the electrostatic chuck and enhance the interfacial bonding strength of the electrode layer and the ceramic substrate has become a key technical bottleneck to be broken through.

[0003] Therefore, the present application is proposed to solve the above technical problems. SUMMARY

[0004] The present application overcomes the shortcomings of the prior art, and provides a special conductive slurry for electrostatic chuck, and a preparation method and application thereof.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows: a special conductive slurry for electrostatic chuck, the conductive slurry comprises the following preparation by mass percentage: tungsten powder 80-85%, neodymium oxide 0.4-0.8%, aluminum oxide 1-1.5%, silicon dioxide 1-1.5%, organic carrier 10-16%, dispersing agent 1.5-2.8%.

[0006] Preferably, the average particle size of the tungsten is any one of 0.5um, 1.0um, 1.5um, and the maximum particle size is less than 3um.

[0007] In a preferred embodiment of the present application, the average particle size of the tungsten is 0.5um, and the maximum particle size is less than 3um.

[0008] Preferably, the dispersing agent is any one of soybean lecithin, nonylphenol polyethylene ether, or a mixture of any two thereof.

[0009] Preferably, the organic carrier comprises 12-25% of resin and 75-88% of organic solvent by mass percentage.

[0010] Preferably, the resin is any one of acrylic resin, ethyl cellulose, or a mixture of any two thereof.

[0011] Preferably, the organic solvent is any one of terpineol, n-butanol, or a mixture of any two thereof.

[0012] The application provides a preparation method of tungsten slurry special for electrostatic chuck, comprising the following steps:

[0013] (1) proportionally weighing tungsten, neodymium oxide and aluminum oxide powder, and ball milling for 2-3 hours by dry ball milling at a speed of 40-60 rpm / min to obtain blended powder A;

[0014] (2) uniformly dispersing the blended powder A and a dispersing agent in an organic carrier at a proportion under the condition of a heating temperature of 40-90 DEG C and a stirring speed of 1800-2100 r / min, cooling to room temperature after mixing preparation, and obtaining a conductive slurry precursor;

[0015] (3) rolling the conductive slurry precursor in a three-roll mill until the fineness of the conductive slurry is less than 10 microns, and defoaming in a double-planetary centrifugal mixer for 3-8 minutes to obtain a conductive tungsten slurry.

[0016] The application provides an application of the conductive slurry special for electrostatic chuck, which is obtained by the preparation method and is used for manufacturing an electrode layer of an electrostatic chuck.

[0017] The application has the following beneficial effects:

[0018] (1) the compactness of the electrode layer after sintering of the conductive slurry is significantly improved, the square resistance is reduced, and the electrostatic chuck has excellent electrostatic adsorption capacity when the conductive slurry is applied to the electrode layer of the electrostatic chuck.

[0019] (2) the added neodymium oxide powder can penetrate into the interior of the ceramic substrate of the electrostatic chuck and form a mechanical interlocking structure with the ceramic during high-temperature co-sintering with the ceramic, thereby enhancing the bonding force between the electrode layer and the ceramic substrate. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a scanning electron microscope (SEM) image of the conductive slurry prepared in Example 3 of the application after sintering;

[0021] Figure 2 is a scanning electron microscope (SEM) image of the conductive slurry prepared in Comparative Example 1 of the application after sintering. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0023] The conductive paste special for electrostatic chuck comprises the following raw materials by mass percentage: tungsten powder 80-85%, neodymium oxide 0.4-0.8%, aluminum oxide 1-1.5%, silicon dioxide 1-1.5%, organic carrier 10-16%, and dispersant 1.5-2.8%.

[0024] In some specific embodiments, the average particle size of tungsten can be 0.5 μm, 1.0 μm, 1.5 μm, and the maximum particle size is less than 3 μm.

[0025] In some specific embodiments, the particle size of neodymium oxide is 3-5 μm.

[0026] In some specific embodiments, the dispersant is any one or mixture of any two of soybean lecithin and nonylphenol polyethylene ether.

[0027] In some specific embodiments, the organic carrier comprises 12-25% of resin and 75-88% of organic solvent by mass percentage; the resin is any one or mixture of any two of acrylic resin and ethyl cellulose; and the organic solvent is any one or mixture of any two of terpineol and n-butanol.

[0028] The present application provides a preparation method of tungsten paste special for electrostatic chuck, comprising the following steps:

[0029] (1) proportionally weighing tungsten, neodymium oxide and aluminum oxide powder, and ball milling for 2-3 h by dry ball milling at a speed of 40-60 rpm / min to obtain blended powder A;

[0030] (2) uniformly dispersing the blended powder A and dispersant in an organic carrier at a heating temperature of 40-90℃ and a stirring speed of 1800-2100 r / min, and cooling to room temperature after mixing and preparation to obtain conductive paste precursor;

[0031] (3) rolling the conductive paste precursor in a three-roll mill until the fineness of the conductive paste is less than 10 μm, and defoaming in a double-planetary centrifugal mixer for 3-8 min to obtain conductive tungsten paste.

[0032] The present application provides an application of the conductive paste special for electrostatic chuck, which is obtained by the preparation method as described above, and is used for manufacturing the electrode layer of electrostatic chuck.

[0033] The following is a detailed description of the general embodiments of the present application in conjunction with specific examples.

[0034] The raw materials of examples 1-6 are different in proportion, and the specific proportion is shown in Table 1, which is measured by mass percentage.

[0035] Table 1

[0036]

[0037] Example 1

[0038] A method for preparing a special tungsten slurry for an electrostatic chuck, comprising the following steps:

[0039] (1) The tungsten, neodymium oxide and aluminum oxide powders are weighed according to the proportion and ball milled for 2.5h by dry ball milling at a speed of 50rpm / min to obtain a blended powder A;

[0040] (2) The blended powder A and dispersant are uniformly dispersed in an organic carrier at a heating temperature of 65℃ and a stirring speed of 1950r / min according to the proportion, and the mixture is prepared and cooled to room temperature after preparation to obtain a conductive slurry precursor;

[0041] (3) The conductive slurry precursor is rolled in a three-roll mill until the fineness of the conductive slurry is less than 10μm, and is defoamed in a double-planetary centrifugal mixer for 6min to obtain a conductive slurry.

[0042] Example 2

[0043] This example is basically the same as example 1, and the difference lies in that the raw materials and the proportion are different, as shown in Table 1.

[0044] Example 3

[0045] This example is basically the same as example 1, and the difference lies in that the raw materials and the proportion are different, as shown in Table 1.

[0046] Example 4

[0047] This example is basically the same as example 1, and the difference lies in that the raw materials and the proportion are different, as shown in Table 1.

[0048] Example 5

[0049] This example is basically the same as example 1, and the difference lies in that the raw materials and the proportion are different, as shown in Table 1.

[0050] Example 6

[0051] This example is basically the same as example 1, and the difference lies in that the raw materials and the proportion are different, as shown in Table 1.

[0052] Example 7

[0053] This example is basically the same as example 1, with the difference that the raw materials and the proportions are different, as shown in table 1.

[0054] Comparative example 1

[0055] This comparative example is basically the same as example 3, with the difference that no neodymium oxide is added.

[0056] Comparative example 2

[0057] This comparative example is basically the same as example 2, with the difference that no neodymium oxide is added.

[0058] Comparative example 3

[0059] This comparative example is basically the same as example 4, with the difference that no neodymium oxide is added.

[0060] Comparative example 4

[0061] This comparative example is basically the same as example 3, with the difference that no aluminium oxide and no neodymium oxide are added.

[0062] Comparative example 5

[0063] This comparative example is basically the same as example 3, with the difference that no silicon dioxide and no neodymium oxide are added.

[0064] Comparative example 6

[0065] This comparative example is basically the same as example 3, with the difference that no aluminium oxide and no silicon dioxide are added.

[0066] Comparative example 7

[0067] This example is basically the same as example 3, with the difference that the raw materials and the proportions are different, the tungsten powder being 82.4% and the neodymium oxide being 0.2%.

[0068] Comparative example 8

[0069] This example is basically the same as example 3, with the difference that the raw materials and the proportions are different, the tungsten powder being 81.1% and the neodymium oxide being 1.5%.

[0070] Comparative example 9

[0071] This comparative example is basically the same as example 3, with the difference that no aluminium oxide, no neodymium oxide and no silicon dioxide are added.

[0072] Test example

[0073] Sintering property: Figure 1 is a scanning electron microscope (SEM) image of the conductive paste according to example 3 of the present invention printed on an alumina green tape with a thickness of 1 mm and sintered;

[0074] Figure 2 is a scanning electron microscope (SEM) image of the sintered body formed by printing the conductive paste of Comparative Example 1 of the present application on an alumina green ceramic tape having a thickness of 1 mm;

[0075] from Figure 1 and Figure 2 As can be seen from the comparison, the sintered body formed by the conductive paste to which neodymium oxide is added has excellent sinterability.

[0076] Bonding force test after co-sintering: The conductive pastes prepared in Examples 1 to 7 and Comparative Examples 1 to 9 were printed on an alumina green ceramic tape having a thickness of 1 mm, and a square pattern having a size of 20 mm*20 mm was printed, and after drying, a tensile test piece was prepared by a process of co-sintering at 1550°C, nickel plating, and soldering, and the maximum tensile force that the lead bent by 90° could withstand within 10 s was measured by the hanging weight method, and the results are shown in Table 2. 2

[0077] Sheet resistance test: The conductive pastes prepared in Examples 1 to 7 and Comparative Examples 1 to 9 were printed on an alumina green ceramic tape through a 420-mesh screen, and the printing thickness was 15 μm, and the size of the ceramic tape was 100 mm*100 mm, and after printing, the printed product was dried at a temperature of 120°C for 30 min, and co-sintering was performed at a temperature of 1600°C for 2 h, and the product was cooled in the furnace, and the surface sheet resistance of the tungsten metallization layer was measured using an SDY-5 type double four-probe tester, and the results are shown in Table 2.

[0078] Table 2

[0079] Test Example Bonding Force (N) Sheet Resistance (mΩ / D) Example 1 24 14.3 Example 2 23 14.6 Example 3 24 14.6 Example 4 24 11.3 Example 5 22 11.7 Example 6 23 11.9 Example 7 23 12.3 Comparative Example 1 20 18.5 Comparative Example 2 19 18.8 Comparative Example 3 19 17.9 Comparative Example 4 16 18.3 Comparative Example 5 15 17.9 Comparative Example 6 13 14.4 Comparative Example 7 20 18.2 Comparative Example 8 22 18.6 Comparative Example 9 9 19.4

[0080] As can be seen from the table, the sheet resistances of Examples 1 to 7 and Comparative Examples 1 to 9 were 14.3 mΩ / □, 14.6 mΩ / □, 14.6 mΩ / □, 11.3 mΩ / □, 11.7 mΩ / □, 11.9 mΩ / □, 12.3 mΩ / □, 18.5 mΩ / □, 18.8 mΩ / □, 17.9 mΩ / □, 18.3 mΩ / □, 17.9 mΩ / □, 14.4 mΩ / □, 18.2 mΩ / □, 18.6 mΩ / □, and 19.4 mΩ / □, respectively. The sheet resistance of the electrode layer formed by the sintered conductive paste is directly related to the degree of sintering densification thereof, and the denser the electrode layer, the lower the surface sheet resistance, and the better the conductivity, and by comparing the sheet resistance values of Examples 1 to 7 with those of Comparative Examples 1 to 5 and Comparative Examples 7 to 9, it can be seen that the sheet resistance values of the former are significantly reduced, which indicates that by adding a specific amount of neodymium oxide to the conductive paste, the densification of the electrode layer can be significantly improved. It is presumed that the reason for this is that Nd 3+ ​In the sintering process, the migration of other ions is inhibited, thereby reducing the grain boundary movement rate, inhibiting the grain growth, and promoting the formation of the dense structure. Although the sheet resistance of the electrode layer of the comparative examples 4-6 is 14.4 mΩ / □, the bonding force is only 14 N, and thus the electrode layer prepared by the conductive paste of the comparative example 6 cannot be applied in the electrostatic chuck.

[0081] As can be seen from the table, the bonding force of the examples 1-7 and the comparative examples 1-9 is respectively: 24 N, 23 N, 24 N, 24 N, 22 N, 23 N, 23 N, 20 N, 19 N, 19 N, 16 N, 15 N, 13 N, 20 N, 22 N, 9 N. It can be seen that the bonding force of the examples 1-7 is higher than that of the comparative examples 1-7 and the comparative example 9. By comparing the bonding force of the comparative example 1 and the example 3, the comparative example 2 and the example 2, and the comparative example 3 and the example 4, it can be seen that the addition of the appropriate amount of neodymium oxide in the conductive paste can further increase the bonding force between the electrode layer and the ceramic substrate. It is speculated that the reason may be that the neodymium oxide has the wetting property. In the sintering process of the aluminum oxide ceramic, the Nd 3+ After entering the aluminum oxide lattice, due to the large difference in radius, the aluminum oxide lattice is deformed to produce defects, which promotes the activation of the lattice, thereby causing the sintering activation energy of the bonding interface between the ceramic substrate and the electrode layer to decrease, which is beneficial to the formation of the dense structure of the bonding interface, thereby enhancing the bonding force between the electrode layer and the ceramic substrate. Although the bonding force of the comparative example 8 is 22, the sheet resistance is 18.6 mΩ / □, and thus the electrode layer prepared by the conductive paste of the comparative example 8 cannot be applied in the electrostatic chuck.

[0082] The above description is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can make equivalent replacements or changes to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. An electrostatic chucking dedicated conductive paste, characterized by, The tungsten powder is 80-85%, the neodymium oxide is 0.4-0.8%, the aluminum oxide is 1-1.5%, the silicon dioxide is 1-1.5%, the organic carrier is 10-16%, and the dispersant is 1.5-2.8% by mass percentage, wherein the dispersant is any one of soybean lecithin and nonylphenol polyethylene ether or a mixture of any two thereof. The preparation method of the electrostatic chuck special conductive paste comprises the following steps: The tungsten, neodymium oxide and aluminum oxide powders are ball milled by a dry method for 2-3 hours at a speed of 40-60 rpm / min to obtain a blended powder A; The blended powder A and the dispersant are uniformly dispersed in the organic carrier at a heating temperature of 40-90 DEG C and a stirring speed of 1800-2100 r / min, and a conductive paste precursor is obtained after cooling; The precursor is rolled to a fineness of less than 10 microns in a three-roll mill and is defoamed for 3-8 minutes to obtain a conductive tungsten paste.

2. The electrostatic chucking special conductive paste according to claim 1, characterized in that, The average particle size of the tungsten is any one of 0.5 microns, 1.0 microns and 1.5 microns, and the maximum particle size is less than 3 microns.

3. The electrostatic chucking special conductive paste as claimed in claim 1, wherein: The average particle size of the tungsten is 0.5 microns.

4. The electrostatic chucking special conductive paste as claimed in claim 1, wherein, The organic carrier comprises 12-25% of a resin and 75-88% of an organic solvent by mass percentage.

5. The electrostatic chucking dedicated conductive paste as claimed in claim 4, wherein: The resin is any one of an acrylic resin and ethyl cellulose or a mixture of any two thereof.

6. The electrostatic chucking special conductive paste as claimed in claim 4, wherein: The organic solvent is any one of a pine oil alcohol and n-butanol or a mixture of any two thereof.

7. Use of an electrostatic chucking specific conductive paste, characterized in that: The electrostatic chuck special conductive paste is obtained by the preparation method of any one of claims 1-6 and is used for manufacturing an electrode layer of an electrostatic chuck.

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