Method for preparing low-roughness yttrium oxide coating

Abstract

A method for preparing a low-roughness yttrium oxide coating, comprising the following steps: step S10. delivering a high-purity sintered aluminum oxide substrate cleaned by means of bombardment using a gas ion source into a first coating process chamber and performing deposition on a surface of the high-purity sintered aluminum oxide substrate in an intermediate frequency magnetron sputtering manner to form an amorphous aluminum oxide transition layer; step S11. conveying the high-purity sintered aluminum oxide substrate comprising the amorphous aluminum oxide transition layer into a cooling chamber and leaving the high-purity sintered aluminum oxide substrate to stand for cooling to a preset temperature; and step S12. conveying the cooled high-purity sintered aluminum oxide substrate into a second coating process chamber and performing deposition on a surface of the amorphous aluminum oxide transition layer in the intermediate frequency magnetron sputtering manner to form an yttrium oxide coating. In the present invention, by depositing the amorphous aluminum oxide transition layer on the surface of the high-purity sintered aluminum oxide substrate, the surface roughness of the high-purity sintered aluminum oxide substrate is reduced, so that the surface roughness of the yttrium oxide coating which is deposited subsequently is reduced, thereby improving the plasma etching resistance of the yttrium oxide coating.

Description

A method for preparing a low-roughness yttrium oxide coating Technical Field

[0001] The present invention relates to the technical field of material surface treatment, and in particular to a method for preparing a low-roughness yttrium oxide coating. Background Art

[0002] At present, in the semiconductor industry, dense high-purity alumina ceramic coatings are often used to protect the surfaces of internal components in etching process chambers. However, with the increase in plasma power and density, higher requirements are placed on the etching resistance of the inner wall of the etching process chamber. Improving the plasma etching resistance of alumina ceramic materials through surface coating is an effective method. Since the surface roughness of ceramic materials is closely related to the plasma etching resistance, in the existing process, directly depositing a yttrium oxide film layer on a high-purity sintered alumina substrate will directly lead to a large surface roughness of the yttrium oxide coating due to the excessive surface roughness of the substrate, making it difficult for the prepared yttrium oxide coating to achieve good plasma etching resistance.

[0003] Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a method for preparing a low-roughness yttrium oxide coating to improve the plasma etching resistance of the yttrium oxide coating.

[0005] A method for preparing a low-roughness yttrium oxide coating comprises the following steps:

[0006] Step S10, the high-purity sintered alumina substrate that has been bombarded and cleaned by a gas ion source is placed into a first coating process chamber, and an amorphous alumina transition layer is deposited on the surface of the high-purity sintered alumina substrate by medium-frequency magnetron sputtering;

[0007] Step S11, transferring the high-purity sintered alumina substrate containing the amorphous alumina transition layer into a cooling chamber and allowing it to cool to a preset temperature;

[0008] In step S12, the cooled high-purity sintered alumina substrate is transferred to a second coating process chamber, and a yttrium oxide coating is deposited on the surface of the amorphous alumina transition layer by medium-frequency magnetron sputtering.

[0009] Compared with the prior art, in the present invention, an amorphous alumina transition layer is deposited on the surface of a high-purity sintered alumina substrate to reduce the surface roughness of the high-purity sintered alumina substrate, thereby reducing the surface roughness of the subsequently deposited yttrium oxide coating, thereby improving the plasma etching resistance of the yttrium oxide coating.

[0010] Furthermore, in step S10, the purity of the high-purity sintered alumina substrate is 99.9%, and the substrate is sintered by cold isostatic pressing.

[0011] Furthermore, before step S10, the preparation method further includes:

[0012] A soft-contact electric forklift is used to transport the high-purity sintered alumina substrate to the positioning platform, and a manipulator automatically sends the high-purity sintered alumina substrate to the cleaning equipment for ultrasonic cleaning and drying;

[0013] The dried high-purity sintered alumina substrate is automatically transferred to the vacuum chamber by a robot for gas ion source bombardment cleaning.

[0014] Furthermore, the gas ion source is a linear anode ion source, the working gas is argon, the voltage is adjustable in the range of 800 to 1000 V, and the bombardment time is 10 to 30 minutes.

[0015] Furthermore, in step S10 , the sputtering voltage of the magnetron sputtering is 300 to 600 V, and the thickness of the amorphous aluminum oxide transition layer is in the range of 1 to 3 μm.

[0016] Furthermore, the amorphous aluminum oxide transition layer is a coating with disordered atomic arrangement and no clear crystal lattice.

[0017] Further, in step S12 , the sputtering voltage of the magnetron sputtering is 400 to 600 V, and the thickness of the yttrium oxide coating is in the range of 5 to 15 μm.

[0018] Furthermore, the sputtering cathodes in the second coating process chamber and the first coating process chamber both adopt rectangular twin cathodes, each of the rectangular twin cathodes is installed on a translation track, and the sputtering cathodes in the rectangular twin cathodes are at the same height from the surface to be coated.

[0019] Furthermore, the distance between the sputtering cathode in the rectangular twin cathode and the surface to be coated is 7 to 12 cm.

[0020] Furthermore, in step S11 , the preset temperature is 25 to 100° C. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a flow chart of a method for preparing a low-roughness yttrium oxide coating according to the present invention;

[0022] FIG2 is a schematic diagram of a production line process for preparing a low-roughness yttrium oxide coating according to the present invention;

[0023] FIG3 is a schematic diagram of the operation of a medium frequency power supply in combination with twin rectangular cathodes in the present invention;

[0024] FIG4 is a schematic structural diagram of a low-roughness yttrium oxide coating according to the present invention;

[0025] FIG5( a ) is an AFM image of the surface of the high-purity sintered alumina substrate of the present invention;

[0026] FIG5( b ) is a surface AFM image of an amorphous aluminum oxide transition layer deposited on the surface of a high-purity sintered aluminum oxide substrate according to the present invention;

[0027] FIG5( c ) is a surface AFM image of a yttrium oxide coating directly deposited on a high-purity sintered alumina substrate according to the present invention;

[0028] FIG5( d ) is a surface AFM image of a high-purity sintered alumina substrate deposited with an amorphous alumina transition layer and then a yttrium oxide coating in the present invention;

[0029] FIG6 is a comparison diagram of the calculation results of the AFM roughness test Ra in the present invention.

[0030] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0031] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0032] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0034] Referring to FIG. 1 and FIG. 2 , a method for preparing a low-roughness yttrium oxide coating according to an embodiment of the present invention includes the following steps:

[0035] Step S10, the high-purity sintered alumina substrate that has been bombarded and cleaned by a gas ion source is placed into a first coating process chamber, and an amorphous alumina transition layer is deposited on the surface of the high-purity sintered alumina substrate by medium-frequency magnetron sputtering;

[0036] Specifically, in step S10 , the sputtering voltage of the magnetron sputtering is 300 to 600 V, and the thickness of the amorphous aluminum oxide transition layer is in the range of 1 to 3 μm.

[0037] Step S11, transferring the high-purity sintered alumina substrate containing the amorphous alumina transition layer into a cooling chamber and allowing it to cool to a preset temperature;

[0038] Specifically, in step S11, the preset temperature is 25 to 100°C.

[0039] In step S12, the cooled high-purity sintered alumina substrate is transferred to a second coating process chamber, and a yttrium oxide coating is deposited on the surface of the amorphous alumina transition layer by medium-frequency magnetron sputtering.

[0040] It should be noted that, in the present application, the amorphous alumina transition layer is a coating layer with disordered atomic arrangement and no clear lattice. The purity of the high-purity sintered alumina substrate is 99.9%, and it is sintered by cold isostatic pressing.

[0041] Further, in step S12 , the sputtering voltage of the magnetron sputtering is 400 to 600 V, and the thickness of the yttrium oxide coating is in the range of 5 to 15 μm.

[0042] It should be further noted that the sputtering cathodes in both the second and first coating process chambers utilize rectangular twin cathodes. Each of the rectangular twin cathodes is mounted on a translational track, and the sputtering cathodes within the rectangular twin cathodes are positioned at the same height from the surface to be coated. In the present invention, the sputtering cathodes are configured as rectangular twin cathodes and mounted on a translational track. When sputtering a large substrate, the cathodes reciprocate within a certain range to ensure uniform film thickness and avoid the sputtering gradients associated with fixed cathodes, which can lead to uneven film thickness.

[0043] Specifically, the distance between the sputtering cathode in the rectangular twin cathode and the surface to be coated is 7 to 12 cm.

[0044] Furthermore, before step S10, the preparation method further includes:

[0045] A soft-contact electric forklift is used to transport the high-purity sintered alumina substrate to the positioning platform, and a manipulator automatically sends the high-purity sintered alumina substrate to the cleaning equipment for ultrasonic cleaning and drying;

[0046] The dried high-purity sintered alumina substrate is automatically transferred to the vacuum chamber by a robot for gas ion source bombardment cleaning.

[0047] Specifically, the gas ion source used in this application is a linear anode ion source, the working gas is argon, the voltage is adjustable from 800 to 1000V, and the bombardment time is 10 to 30 minutes. The purpose is to remove the water molecule film and organic matter remaining on the substrate surface after pretreatment. The particle bombardment also activates the substrate and improves the film-substrate bonding.

[0048] It should be noted that, in this application, when the vacuum degree of the cavity is 8×10 -4 to 1×10 -3 The coating process can begin within the Pa range. After the first set of high-purity sintered alumina substrates with amorphous alumina transition layer deposited enters the cooling chamber, the next set of sample substrates stored in the ion source gas chamber will then enter the first coating process chamber for amorphous alumina transition layer deposition. Therefore, the sputtering cathode does not need to stop working, improving sputtering efficiency.

[0049] The following is an example of preparing yttrium oxide coating:

[0050] First, preprocessing:

[0051] In a Class 1000 dust-free workshop, a soft-contact electric forklift is used to transfer the high-purity sintered alumina substrate to the positioning platform. After the substrate is adjusted to the appropriate position, a forklift is used to transfer the substrate to the cleaning equipment.

[0052] A barcode scanner is used to extract product dimensions. The automated cleaning and transfer section adaptively adjusts the position of the manipulator, lifting fixture, and transfer wheels based on the product dimensions. A forklift lifts the substrate to the robotic gripper position at the front of the cleaning machine, where it is automatically transferred to the cleaning equipment for cleaning. The cleaning process includes: ultrasonic cleaning with a chemical solution—one ultrasonic rinse—two ultrasonic rinses—scanning spray—clean air dewatering—vacuum dehydration—and cleanliness inspection.

[0053] In order to prevent the high-purity sintered alumina substrate from being attached by tiny particles after cleaning, this stage enters a fully automatic transfer process, including: tray splicing - tray transmission - robot grasping - substrate rack receiving substrate - substrate rack transmission to the cleaning area in the vacuum chamber.

[0054] Second, amorphous aluminum oxide transition layer deposition

[0055] Multiple groups of substrates enter the storage chamber - vacuum is applied - working gas argon is introduced - the first group of substrates enters the ion source chamber - gas plasma surface cleaning - the first group of substrates enters the first coating process chamber, and the second group of substrates enters the ion source chamber for gas plasma cleaning - the angle and height of the sputtering cathode are adjusted to deposit an amorphous aluminum oxide transition layer - the first group of substrates undergoes low-roughness medium-frequency magnetron sputtering to deposit an amorphous aluminum oxide transition layer - the first group of substrates enters the cooling chamber for static cooling, the second group of substrates enters the first coating process chamber for deposition of an amorphous aluminum oxide transition layer, and at the same time the third group of substrates enters the ion source chamber - the above steps are repeated until all substrates complete the deposition of the amorphous aluminum oxide transition layer.

[0056] Third, yttrium oxide coating deposition

[0057] After the first group of substrates are cooled in the cooling chamber, they enter the second coating process chamber - the angle and height of the sputtering cathode are adjusted to deposit the yttrium oxide coating - the first group of substrates undergoes medium-frequency magnetron sputtering to deposit the yttrium oxide coating - after the preset time is reached, they are transported to the storage chamber for cooling, and then the second group of substrates enter the second coating process chamber for deposition of the yttrium oxide coating - the above steps are repeated until all substrates complete the yttrium oxide coating deposition.

[0058] Fourth, finished product testing

[0059] The finished products are tested for surface roughness parameters such as surface average roughness Ra, maximum height roughness Rmax, root mean square roughness Rq and arithmetic mean height Sa. At the same time, the coating surface integrity is checked to see if there are cracks or wrinkles, etc., to determine whether they meet the standards. After passing the inspection, they are transferred to a nitrogen protection storage box.

[0060] Refer to Figure 3 , which shows a sample prepared in another embodiment of the present invention. Specifically, a high-purity sintered alumina substrate measuring 30×30×3mm was pretreated and then sent to an ion source chamber for ion bombardment cleaning. The substrate was then transferred to a coating chamber and reactively sputtered at 300V for 3 hours using a medium-frequency power supply and twin cathodes, depositing an amorphous alumina transition layer approximately 2μm thick on its surface. After deposition, the substrate was cooled to 30°C, and reactive sputtering was performed using the same method at 600V for 10 hours, depositing an approximately 10μm thick yttrium oxide coating on the substrate surface. The finished product was then characterized and tested using AFM.

[0061] As shown in Figure 4, the coating deposition uses a medium-frequency power supply and a rectangular twin cathode. This combination effectively reduces target poisoning during coating deposition and stabilizes the sputtering process. The rectangular twin cathode can accommodate different target materials as needed. Mounted on a translational track with the medium-frequency power supply, it reciprocates along the track during the coating process, improving the uniformity of deposited coatings on large substrates.

[0062] Refer to Figures 5(a) through 6, where AFM was used to characterize the surface morphology of a high-purity sintered alumina substrate before and after the deposition of an amorphous alumina transition layer, as well as four samples with yttrium oxide coatings deposited on two substrates. The changes in roughness are clearly visible in the 3D AFM topography. Calculation of the arithmetic mean deviation (Ra) of the profiles shows that the high-roughness, high-purity sintered alumina surface becomes smoother after sputtering the amorphous alumina transition layer, reducing the surface roughness from 222nm to 14.7nm. Furthermore, the construction of the transition layer also significantly affects the yttrium oxide coating. With the sputtered transition layer, the surface roughness of the yttrium oxide coating is reduced from 48nm to 4.4nm, representing only 9.2% of the roughness of the unsputtered transition layer. In summary, sputtering an amorphous alumina transition layer onto the surface of a high-purity sintered alumina substrate effectively reduces the roughness of the yttrium oxide coating.

[0063] In summary, the present invention reduces the roughness of the high-purity sintered alumina surface and improves the uniformity of the coating by depositing an amorphous alumina transition layer, providing conditions for the medium-frequency magnetron sputtering deposition of a low-roughness yttrium oxide coating, while improving the coating quality and having good plasma etching resistance.

[0064] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a low-roughness yttrium oxide coating, characterized in that: The following steps are involved: Step S10, sending the high-purity sintered alumina substrate after gas ion source bombardment cleaning into the first coating process chamber, and depositing an amorphous alumina transition layer on the surface of the high-purity sintered alumina substrate by medium frequency magnetron sputtering, wherein the sputtering voltage of the magnetron sputtering is 300 to 600 V, and the thickness of the amorphous alumina transition layer ranges from 1 to 3 μm; Step S11, transferring the high-purity sintered alumina substrate containing the amorphous alumina transition layer into a cooling chamber, and cooling it to a preset temperature by standing; Step S12, transferring the cooled high-purity sintered alumina substrate to a second coating process chamber, and using medium-frequency magnetron sputtering to deposit a yttrium oxide coating on the surface of the amorphous alumina transition layer, wherein the sputtering voltage of the magnetron sputtering is 400 to 600 V, and the thickness of the yttrium oxide coating ranges from 5 to 15 μm.

2. The method for preparing a low-roughness yttrium oxide coating according to claim 1, characterized in that: In step S10, the purity of the high-purity sintered alumina substrate is 99.9%, and it is sintered by cold isostatic pressing.

3. The method for preparing a low-roughness yttrium oxide coating according to claim 1, characterized in that: Before step S10, the preparation method further includes: A soft-contact electric forklift is used to transfer the high-purity sintered alumina substrate to the positioning stand, and a manipulator is used to automatically send the high-purity sintered alumina substrate to the cleaning equipment for ultrasonic cleaning and drying; The dried high-purity sintered alumina substrate is automatically transferred to the vacuum chamber by a robot for gas ion source bombardment cleaning.

4. The method for preparing a low-roughness yttrium oxide coating according to claim 3, characterized in that: The gas ion source is a linear anode ion source, the working gas is argon, the voltage can be adjusted in the range of 800 to 1000 V, and the bombardment time is 10 to 30 min.

5. The method for preparing a low-roughness yttrium oxide coating according to claim 1, characterized in that: The amorphous aluminum oxide transition layer is a coating layer with disordered atomic arrangement and no clear crystal lattice.

6. The method for preparing a low-roughness yttrium oxide coating according to claim 1, characterized in that: The sputtering cathodes in the second coating process chamber and the first coating process chamber both adopt rectangular twin cathodes, each of the rectangular twin cathodes is installed on a translation track, and the sputtering cathodes in the rectangular twin cathodes are at the same height from the surface to be coated.

7. The method for preparing a low-roughness yttrium oxide coating according to claim 6, characterized in that: The distance between the sputtering cathode in the rectangular twin cathode and the surface to be coated is 7 to 12 cm.

8. The method for preparing a low-roughness yttrium oxide coating according to any one of claims 1 to 7, characterized in that: In step S11, the preset temperature is 25 to 100°C.

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