A process for making an aluminum-titanium thermal spray composite coating applied to a semiconductor device cavity

Abstract

The application belongs to the technical field of thermal spraying, and particularly relates to a manufacturing process of an aluminum-titanium fused spraying composite coating applied to a semiconductor equipment cavity, which comprises the following steps: (1) using white corundum sand to sand blast the semiconductor equipment cavity; (2) removing residual sand, cleaning, drying treatment, and obtaining a pretreated semiconductor equipment cavity; (3) using supersonic flame to fuse spray aluminum wire on the surface of the pretreated semiconductor equipment cavity, and obtaining an aluminum fused spraying coating; (4) using supersonic flame to fuse spray titanium wire on the surface of the aluminum fused spraying coating, obtaining a titanium fused spraying coating, and cleaning, drying and vacuum heat treatment. The composite coating prepared by the application has a roughness meeting the requirements, a relatively high fused spraying bonding force, a coating not easy to fall off, a low porosity and a denser coating.

Description

Technical Field

[0001] This invention belongs to the field of spraying technology, specifically relating to a process for fabricating an aluminum-titanium spraying composite coating for semiconductor device cavities. Background Technology

[0002] In semiconductor manufacturing, physical vapor deposition (PVD) is a key process for forming thin films such as metals and nitrides on silicon wafers or glass substrates. However, during this process, not only the target substrate deposits the required thin film, but the internal components of the PVD chamber also inevitably adsorb these materials. To enhance the adhesion of the deposited film to these semiconductor device chambers, prevent film peeling, and reduce the generation of particles within the chamber, thereby extending the lifespan of the semiconductor device chamber and improving the operating efficiency of the equipment, commonly used methods include sandblasting and arc spraying to increase the surface roughness of the semiconductor device chamber.

[0003] ARC spraying is a surface thermal spraying technology. After a series of pretreatments such as sandblasting and cleaning, molten spray coating droplets are sprayed onto the substrate surface through airflow. The mechanical bonding force of the coating cooling and spreading is used to cover the substrate surface with a relatively uniform and rough coating.

[0004] Spray coatings used in semiconductor device cavities still face several challenges, particularly in three key performance indicators: roughness, adhesion, and porosity. 1. Roughness: During spraying, variations in spray angle, speed, and temperature can lead to uneven surface roughness, with some areas exhibiting excessively high or low roughness. Precise control of the size and distribution of sprayed particles results in an unsatisfactory microstructure, affecting smoothness and evenness. Rough surfaces easily accumulate processing residues, increasing particle generation, which is extremely detrimental to the semiconductor manufacturing environment and can lead to higher product defect rates. Excessively rough surfaces may result in insufficient adhesion of the deposited film, increasing the risk of film peeling. 2. Adhesion: During spraying, improper substrate surface treatment or unsuitable spraying parameters can create interface defects between the coating and substrate, such as voids and cracks, weakening adhesion. Due to the different coefficients of thermal expansion between the substrate and coating materials, thermal stress is generated during heating and cooling, potentially causing coating cracking or peeling. Insufficient adhesion can cause the coating to gradually peel off during use, shortening its service life and requiring frequent maintenance and replacement, thus increasing production costs. Coating peeling can also affect the corrosion resistance and wear resistance of the cavity, thereby reducing the overall performance and reliability of the equipment. 3. Porosity: During the spraying process, if the sprayed particles fail to fuse sufficiently, or if air is introduced during spraying, it may lead to the formation of numerous pores within the coating. Uneven pore distribution: Uneven pore size and distribution may concentrate in certain areas, forming weak points and affecting the overall performance of the coating. Pores provide a penetration path for corrosive media, reducing the coating's corrosion resistance, especially when exposed to chemicals during semiconductor manufacturing, making it more susceptible to corrosion. High porosity weakens the mechanical strength of the coating, making it more vulnerable to damage under high temperature, high pressure, or mechanical stress.

[0005] Current technologies primarily utilize more refined surface cleaning and pretreatment techniques, such as laser cleaning and chemical etching, to ensure a clean substrate surface with appropriate roughness, thereby enhancing coating adhesion. However, the porosity of the coating still falls short of customer requirements. Furthermore...

[0006] Therefore, there is an urgent need for a process for fabricating aluminum-titanium composite coatings for semiconductor device cavities. Summary of the Invention

[0007] The purpose of this invention is to provide a process for fabricating aluminum-titanium composite coatings for semiconductor device cavities.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A process for fabricating an aluminum-titanium composite coating for semiconductor device cavities includes the following steps:

[0010] (1) Sandblasting the semiconductor equipment cavity with white corundum abrasive;

[0011] (2) First, use high-pressure water washing to remove residual sand, then perform ultrasonic cleaning, and finally use nitrogen to blow dry and dry in an oven to obtain a pre-treated semiconductor equipment cavity;

[0012] (3) Use a supersonic flame to spray aluminum wire onto the surface of the pre-processed semiconductor device cavity to obtain an aluminum spray coating; the supersonic flame spraying conditions in step (3) are: current: 180-200A, voltage 25-30V, spraying distance 150-180mm, compressed air pressure 40-50psi.

[0013] (4) Use a supersonic flame to spray titanium wire onto the surface of the aluminum spray coating. The supersonic flame spraying conditions in step (4) are: current: 180-200A, voltage 25-30V, spraying distance 150-180mm, compressed air pressure 40-50psi. A titanium spray coating is obtained, and after cleaning, drying and vacuum heat treatment, an aluminum-titanium spray composite coating for use in semiconductor equipment cavities is obtained.

[0014] Existing aluminum spraying processes used in the electronics industry mainly include two methods: ARC (arc) spraying and flame spraying. ARC spraying is prone to producing spray dust, resulting in a high particle size. Current technologies typically combine ARC and flame spraying to improve this issue, but this increases costs. This invention optimizes the entire process, using only ARC spraying, and further improves the high particle size problem by optimizing supersonic flame spraying conditions. Simultaneously, the spraying conditions of this invention improve the adhesion of the composite coating.

[0015] Furthermore, in step (1), white corundum abrasive with a mesh size of 20-30# is used to sandblast the cavity of the semiconductor device.

[0016] Furthermore, in step (1), the sandblasting pressure is 0.3-0.5 MPa and the sandblasting distance is 160-180 mm.

[0017] Furthermore, in step (2), the high-pressure water washing uses water with a resistivity of 6-8 MΩ. cm of deionized water, with a water pressure of 70-80 bar.

[0018] Furthermore, in step (2), the ultrasonic cleaning uses a resistivity of 6-8 MΩ. cm of deionized water, with an ultrasonic intensity of 8-10 W / inch. 2 .

[0019] Furthermore, in step (2), the drying time is 2-3 hours and the drying temperature is 145-155°C.

[0020] Furthermore, the supersonic flame spraying conditions in step (3) are: current: 180A, voltage: 25V, spraying distance: 150mm, compressed air pressure: 40psi.

[0021] Furthermore, the supersonic flame spraying conditions in step (4) are: current: 180A, voltage: 25V, spraying distance: 150mm, compressed air pressure: 40psi.

[0022] Further, the vacuum heat treatment conditions in step (4) are as follows: vacuum degree 4-6 mtorr, first at 260-270℃, heat preservation for 1-2h; then at 230-240℃, heat preservation for 3-4h; finally at 200-210℃, heat preservation for 1-2h, and then cooling with the furnace.

[0023] This invention utilizes a gradient vacuum heat treatment method to improve the porosity of composite coatings. Under the vacuum heat treatment conditions of this invention, the diffusion of metal atoms gradually allows atoms in the coating material to migrate and fill tiny pores, while simultaneously helping to release residual stress within the composite coating and reducing crack and pore propagation caused by stress concentration.

[0024] Furthermore, the purity of the titanium wire is ≥99.999%. It was purchased from Beijing Juguang Wintech Technology Co., Ltd.

[0025] Furthermore, the thickness of the aluminum spray coating in step (3) is 50±20μm, and the thickness of the titanium spray coating in step (4) is 100±30μm.

[0026] Furthermore, the ratio of the thickness of the aluminum spray coating to the thickness of the titanium spray coating is 1:(1.6-2.4).

[0027] During the experiment, it was found that the thickness of the aluminum and titanium spray coatings can affect the adhesion of the composite coating. A thickness of 50±20 μm for the aluminum spray coating and 100±30 μm for the titanium spray coating can improve the adhesion of the composite coating. This is because the thickness of the aluminum and titanium spray coatings is closely related to the spraying conditions and vacuum heat treatment of this invention; the synergistic effect of these three factors can improve the adhesion of the composite coating. The aluminum layer, as the bottom layer, provides initial protection and adhesion. An appropriate thickness ensures that the aluminum layer uniformly covers the substrate surface and can withstand the impact and heat during the subsequent titanium layer spraying. The adhesion between the titanium and aluminum layers directly affects the stability of the entire composite coating. A titanium layer of appropriate thickness can provide sufficient protection and bonding strength without adding excessive stress. There is a synergistic effect among the thickness of the aluminum and titanium layers, the spraying conditions, and the vacuum heat treatment; reasonable thickness selection ensures good matching between the layers, while optimized spraying conditions guarantee the quality of the coating; vacuum heat treatment further enhances the overall adhesion and stability of the coating through stress release, diffusion, and chemical reactions. Furthermore, by optimizing the above process steps, a composite coating with high adhesion, low porosity, and excellent durability can be obtained; this not only improves the performance of the coating at room temperature, but also ensures its long-term reliability in harsh working environments such as high temperature and high pressure.

[0028] Furthermore, during the experiment, it was found that when the ratio of the thickness of the aluminum spray coating to the thickness of the titanium spray coating is within the range of 1:(1.6-2.4), the adhesion of the composite coating under varying temperatures can be improved. The thermal expansion coefficients of the substrate, aluminum layer, and titanium layer are typically different. When the temperature changes, the expansion degrees of each layer differ, which may lead to stress concentration, especially at the interface, potentially causing coating peeling or cracking. When the thickness of the aluminum spray coating to the thickness of the titanium spray coating is within a specific range, specifically when the ratio is 1:(1.6-2.4), the adhesion of the composite coating under varying temperatures can be effectively improved. This ratio helps to balance the stress between the layers, optimize the microstructure, and under these conditions, vacuum heat treatment can better enhance the adhesion and overall performance of the coating by releasing stress, promoting diffusion, and forming stable intermetallic compounds.

[0029] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0030] 1. This invention provides a process for fabricating an aluminum-titanium composite coating for semiconductor device cavities. The prepared composite coating has the required roughness, high bonding strength, is not easy to peel off, has low porosity, and is more dense.

[0031] 2. This invention uses only ARC (arc) sputtering. By optimizing the supersonic flame sputtering conditions, the problem of excessive particle size can be improved. Under normal circumstances, a measurement result of less than 1 is sufficient to meet the requirements of semiconductor processes below 28nm. At the same time, the sputtering conditions of this invention can improve the adhesion of composite coatings.

[0032] 3. The present invention improves the porosity of the composite coating by performing vacuum heat treatment on the composite coating through gradient treatment.

[0033] 4. The thickness of the aluminum spray coating and the titanium spray coating in this invention can be affected. The thickness of the aluminum spray coating is 50±20μm and the thickness of the titanium spray coating is 100±30μm, which can improve the adhesion of the composite coating.

[0034] 5. In this invention, when the ratio of the thickness of the aluminum spray coating to the thickness of the titanium spray coating is in the range of 1:(1.6-2.4), the bonding strength of the composite coating under varying temperatures can be improved. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1

[0037] This embodiment provides a process for fabricating an aluminum-titanium composite coating for semiconductor device cavities, including the following steps:

[0038] (1) Use white corundum abrasive with a mesh size of 24# to blast the PVD equipment cavity (physical deposition cavity); blasting pressure 0.4 MPa, blasting distance 170 mm;

[0039] (2) First, use high-pressure water washing to remove residual sand. The high-pressure water washing uses a resistivity of 8MΩ. The solution is diluted with deionized water at a pressure of 75 bar; then ultrasonic cleaning is performed using a water with a resistivity of 8 MΩ. cm of deionized water, with an ultrasonic intensity of 9 W / inch. 2 Finally, the cavity is dried with nitrogen and then dried in an oven for 3 hours at a temperature of 150°C to obtain the pre-treated semiconductor device cavity.

[0040] (3) Aluminum wire was sprayed onto the surface of the pre-processed semiconductor equipment cavity using a supersonic flame. The supersonic flame spraying conditions were: current: 180A, voltage: 25V, spraying distance: 150mm, compressed air pressure: 40psi; an aluminum spray coating was obtained; the aluminum spray coating was 50μm; the aluminum wire grade was 1070A.

[0041] (4) Titanium wire with a purity ≥99.999% was deposited onto the surface of the aluminum fusion coating using a supersonic flame. The titanium wire was purchased from Beijing Juguang Yingchuang Technology Co., Ltd. The supersonic flame deposition conditions were: current: 180A, voltage: 25V, deposition distance: 150mm, and compressed air pressure: 40psi. A titanium fusion coating with a thickness of 100μm was obtained. After cleaning, drying, and vacuum heat treatment, the vacuum heat treatment conditions were: vacuum degree: 5mtorr, first at 265℃ for 1.5h, then at 235℃ for 3.5h, and finally at 205℃ for 1.5h, followed by furnace cooling. An aluminum-titanium fusion composite coating for use in semiconductor equipment cavities was obtained.

[0042] Table 1 shows the supersonic flame spraying conditions for steps (3) and (4).

[0043]

[0044] The difference between Examples 2-6 and Comparative Examples 1-3 and Example 1 is that the supersonic flame spraying conditions are different, as detailed in Table 1.

[0045] Comparative Example 4

[0046] The difference between this comparative example and Example 1 is that the supersonic flame spraying conditions are: current: 170A, voltage: 20V, spraying distance: 180mm, and compressed air pressure: 35psi.

[0047] Comparative Example 5

[0048] The difference between this comparative example and Example 1 is that the supersonic flame spraying conditions are: current: 210A, voltage: 35V, spraying distance: 180mm, and compressed air pressure: 55psi.

[0049] Comparative Example 6

[0050] The difference between this comparative example and Example 1 is that the vacuum heat treatment conditions are as follows: the vacuum degree is 5 mtorr, first at 280°C for 3 hours; then at 250°C for 1 hour; and finally at 180°C for 3 hours, followed by furnace cooling.

[0051] Comparative Example 7

[0052] The difference between this comparative example and Example 1 is that the vacuum heat treatment conditions are: vacuum degree 5 mtorr, temperature 260℃, holding time 7h, and then cooling with the furnace.

[0053] Comparative Example 8

[0054] The difference between this comparative example and Example 1 is that the thickness of the aluminum spray coating in step (3) is 100 μm, and the thickness of the titanium spray coating in step (4) is 50 μm.

[0055] Comparative Example 9

[0056] The difference between this comparative example and Example 1 is that the thickness of the aluminum spray coating in step (3) is 75 μm, and the thickness of the titanium spray coating in step (4) is 75 μm.

[0057] Performance testing

[0058] The performance of the composite coatings of Examples 1-6 and Comparative Examples 1-9 was tested.

[0059] 1. Refer to GB / T8642-2002 to determine the bonding strength between the composite coating and the cavity under 25℃ and variable temperature conditions; the variable temperature conditions are: place the composite coating at 25℃, 70℃ and 100℃ for 24h each, and then measure the bonding strength at 25℃.

[0060] 2. Roughness shall be determined in accordance with GB / T131-2009;

[0061] 3. The porosity was determined using a LEICADMI 5000M electron microscope.

[0062] 4. Simulate the actual use environment of the composite coating, observe the time during which the coating does not crack or peel off, calculate the service life, and evaluate the impact of long-term thermal stress on the bonding strength.

[0063] The results are shown in Table 1.

[0064] Table 1 Performance Test Results

[0065]

[0066] The performance test results above show that the composite coatings of Examples 1-6 exhibit excellent overall performance, especially Example 1, which demonstrates the most outstanding overall performance, with an adhesion strength as high as 36 MPa and a porosity of 2.2%. Furthermore, the particle size distribution (ea ≥ 0.3 μm) of Example 1 is 0.31 / cm². 2 Under normal circumstances, a measurement result less than 1 is sufficient to meet the requirements of semiconductor process technology below 28nm. The detection values ​​ea ≥ 0.3μm in Examples 2-6 are also all within the range of 0.50~1 / cm. 2 Within the range.

[0067] The comparative examples, lacking the necessary technical solutions, showed significantly inferior performance compared to the embodiments. In Comparative Examples 1-3, altered spraying distances resulted in decreased adhesion and worsened temperature resistance. In Comparative Examples 4-5, changes in current, voltage, and compressed air pressure further reduced adhesion and worsened temperature resistance, demonstrating that the composite coating only achieves high performance under the supersonic flame spraying conditions of this invention. In Comparative Examples 6-7, different vacuum heat treatment conditions resulted in decreased porosity of the coating. Comparative Examples 8-9 showed that changing the thickness of the aluminum and titanium layers reduced adhesion under varying temperatures, and also decreased the lifespan of the composite coating. These experimental results further demonstrate the importance of the technical solutions defined in this invention for its technical effectiveness.

[0068] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process for fabricating an aluminum-titanium composite coating for semiconductor device cavities, characterized in that, Includes the following steps: (1) Sandblasting the semiconductor equipment cavity with white corundum abrasive; (2) First, use high-pressure water washing to remove residual sand, then perform ultrasonic cleaning, and finally use nitrogen to blow dry and dry in an oven to obtain a pre-treated semiconductor equipment cavity; (3) Use a supersonic flame to spray aluminum wire onto the surface of the pre-processed semiconductor equipment cavity to obtain an aluminum spray coating; The conditions for supersonic flame spraying are: current of 180-200A, voltage of 25-30V, spraying distance of 150-180mm, compressed air pressure of 40-50psi; and aluminum spray coating thickness of 50±20μm. (4) Titanium wire is sprayed onto the surface of the aluminum spray coating using a supersonic flame to obtain a titanium spray coating. After cleaning, drying and vacuum heat treatment, the vacuum heat treatment conditions are: vacuum degree 4-6 mtorr, first at 260-270℃ for 1-2h; then at 230-240℃ for 3-4h; and finally at 200-210℃ for 1-2h, followed by furnace cooling. An aluminum-titanium melt-spray composite coating was obtained for use in semiconductor device cavities; The conditions for supersonic flame spraying are: current of 180-200A, voltage of 25-30V, spraying distance of 150-180mm, compressed air pressure of 40-50psi; and the thickness of the titanium sprayed coating is 100±30μm. The ratio of the thickness of the aluminum spray coating to the thickness of the titanium spray coating is 1:(1.6-2.4).

2. The process for fabricating an aluminum-titanium composite coating for semiconductor device cavities according to claim 1, characterized in that, In step (1), white corundum abrasive with a mesh size of 20-30# is used to sandblast the cavity of the semiconductor device.

3. The process for fabricating an aluminum-titanium composite coating for semiconductor device cavities according to claim 1, characterized in that, In step (1), the sandblasting pressure is 0.3-0.5 MPa and the sandblasting distance is 160-180 mm.

4. The process for fabricating an aluminum-titanium composite coating for semiconductor device cavities according to claim 1, characterized in that, In step (2), the high-pressure water washing uses water with a resistivity of 6-8 MΩ. cm of deionized water, with a water pressure of 70-80 bar.

5. The process for fabricating an aluminum-titanium composite coating for semiconductor device cavities according to claim 1, characterized in that, In step (2), the ultrasonic cleaning uses a resistivity of 6-8 MΩ. cm of deionized water, with an ultrasonic intensity of 8-10 W / inch. 2 .

6. The process for fabricating an aluminum-titanium composite coating for semiconductor device cavities according to claim 1, characterized in that, The drying time in step (2) is 2-3 hours and the drying temperature is 145-155℃.

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