A method for preparing heat-shock-resistant aluminum oxide coating

Abstract

A method for preparing a heat-shock-resistant aluminum oxide coating comprises the following steps: placing an oxygen-free copper substrate, which has been cleaned by bombardment with a gas ion source, into a first coating process chamber, and performing synchronous sputtering using a pulsed DC magnetron sputtering method using dual targets to form a nickel-chromium composite gradient transition layer transitioning from a pure nickel layer to a pure chromium layer on the surface of the oxygen-free copper substrate; transferring the oxygen-free copper substrate with the nickel-chromium composite gradient transition layer deposited on the surface into a cooling chamber, and allowing it to cool to a preset temperature; transferring the cooled oxygen-free copper substrate with the nickel-chromium composite gradient transition layer deposited on the surface into a second coating process chamber, and performing sputtering using a medium-frequency magnetron sputtering method to deposit an aluminum oxide coating on the surface of the nickel-chromium composite gradient transition layer. By depositing a composite gradient transition layer transitioning from a pure nickel layer to a pure chromium layer on the surface of the oxygen-free copper substrate, the present invention reduces the gradient of the thermal expansion coefficient between the oxygen-free copper substrate and the aluminum oxide coating, reduces the accumulation of thermal stress at the interface between the two during temperature fluctuations, and thereby improves the heat-shock resistance of the aluminum oxide coating.

Description

Technical Field

[0001] The invention relates to the technical field of material surface treatment, in particular to a method for preparing a heat-shock-resistant aluminum oxide coating. Background Art

[0002] Currently, in the etching process of the semiconductor industry, some components in the etching process chamber will be loaded with ultra-high power in a short period of time, causing the temperature of the components themselves to be very high. Usually, corresponding copper components are required to exchange heat and cool the components.

[0003] Since the copper component is located in the etching chamber, it will be etched by the plasma during the etching process. Currently, the main way to protect the surface of the copper component is to coat it with a film (preparing an etching-resistant aluminum oxide coating on the surface of the copper component). However, due to the large difference in thermal expansion coefficient between the copper substrate and the aluminum oxide coating (the thermal expansion coefficient of copper is 17.2×10 -6 / ℃, the thermal expansion coefficient of aluminum oxide is about 7.2×10 -6 / ℃), when the temperature changes, the deformation of the two at the interface is inconsistent, and the huge accumulated thermal stress will cause the aluminum oxide coating to fall off and fail, making it difficult to achieve actual protection effect. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a composite gradient transition layer of nickel and chromium (the thermal expansion coefficient of nickel is 13.3×10 -6 / ℃, the thermal expansion coefficient of chromium is about 6.2×10 -6 / ℃) to solve the mismatch problem caused by the large difference in thermal expansion coefficient between the oxygen-free copper substrate and the alumina coating, thereby improving the thermal shock resistance of the alumina coating.

[0005] A method for preparing a heat-shock-resistant aluminum oxide coating comprises the following steps:

[0006] Step S11, the oxygen-free copper substrate after being bombarded and cleaned by a gas ion source is sent into a first coating process chamber, and dual targets are used for synchronous sputtering by pulsed DC magnetron sputtering to form a nickel-chromium composite gradient transition layer transitioning from a pure nickel layer to a pure chromium layer on the surface of the oxygen-free copper substrate, wherein as the deposition process proceeds, the sputtering voltage of the nickel target is gradually reduced, and the sputtering voltage of the chromium target is synchronously gradually increased;

[0007] Step S12, transferring the oxygen-free copper substrate with the nickel and chromium composite gradient transition layer deposited on the surface to a cooling chamber, and cooling it to a preset temperature;

[0008] In step S13, the cooled oxygen-free copper substrate with the nickel and chromium composite gradient transition layer deposited on the surface is transferred to a second coating process chamber and sputtered by medium-frequency magnetron sputtering to deposit an aluminum oxide coating on the surface of the nickel and chromium composite gradient transition layer.

[0009] Compared with the existing technology, the present invention reduces the gradient of the thermal expansion coefficient between the oxygen-free copper substrate and the alumina coating by depositing a composite gradient transition layer from a pure nickel layer to a pure chromium layer on the surface of the oxygen-free copper substrate, and reduces the accumulation of thermal stress at the interface between the two during temperature rise and fall, thereby improving the heat shock resistance of the alumina coating.

[0010] Preferably, in step S11, the contact surface of the nickel-chromium composite gradient transition layer with the oxygen-free copper substrate is a pure nickel layer, and the contact surface with the aluminum oxide coating is a pure chromium layer.

[0011] Preferably, in step S11, the thickness of the nickel-chromium composite gradient transition layer is 0.5-2 μm, the sputtering voltage of the nickel target gradually decreases from a preset voltage to 0V, and the sputtering voltage of the chromium target gradually increases from 0V to a preset voltage.

[0012] Preferably, in step S11, the oxygen-free copper substrate is fixed on a substrate rack, and the substrate rack is provided with a pulse bias power supply for applying a negative bias voltage to the oxygen-free copper substrate and a heating device for heating the oxygen-free copper substrate.

[0013] Preferably, the pulse bias voltage range is 50-300 V, and the heating temperature range is 25-300° C.

[0014] Preferably, before step S11, the method for preparing the heat-shock-resistant alumina coating further comprises:

[0015] A soft-contact electric forklift is used to transport the oxygen-free copper substrate to the positioning platform, and the robot automatically sends the oxygen-free copper substrate to the cleaning equipment for ultrasonic cleaning and drying;

[0016] The dried oxygen-free copper substrate is automatically transferred to the vacuum chamber by a robot and bombarded and cleaned by a gas ion source.

[0017] Preferably, the gas ion source is a linear anode ion source, the working gas is argon, the voltage is adjustable in the range of 800-1200 V, and the bombardment time is 10-30 min.

[0018] Preferably, in step S12, the preset temperature is 25-75°C.

[0019] Preferably, in step S13, the voltage of magnetron sputtering is 400-600 V, and the thickness of the aluminum oxide coating is 2-6 μm.

[0020] Preferably, the two sputtering cathodes in the first coating process chamber are mounted on a first translation track, and the height of the magnetron sputtering cathodes from the surface to be coated is consistent;

[0021] The two sputtering cathodes in the second coating process chamber are mounted on a second translation track, and the height of the magnetron sputtering cathodes from the surface to be coated is consistent;

[0022] The distance between each sputtering cathode and the surface to be coated is 8~15 cm. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Flowchart of the method for preparing the heat-shock-resistant alumina coating of the present invention;

[0024] Figure 2 This is a schematic diagram of the production line process for preparing the heat-shock-resistant alumina coating of the present invention;

[0025] Figure 3 Schematic diagram of co-sputtering of the sputtering cathode in the first coating process chamber of the present invention;

[0026] Figure 4 Schematic diagram of co-sputtering of the sputtering cathode in the second coating process chamber of the present invention;

[0027] Figure 5 Schematic diagram of the structure of the heat-shock-resistant alumina coating of the present invention;

[0028] Figure 6 The overall appearance and surface element characterization of the alumina coating directly deposited on the oxygen-free copper substrate of the present invention after a rapid temperature rise and fall cycle from RT to 300°C in an atmospheric environment;

[0029] Figure 7 The overall appearance and surface element characterization results of the aluminum oxide coating after 20 cycles of rapid temperature increase and decrease from RT to 300°C in an atmospheric environment after depositing a nickel + chromium double-layer transition layer on the oxygen-free copper substrate in the present invention;

[0030] Figure 8 The overall appearance and surface element characterization results of the alumina coating after 100 rapid temperature cycles from RT to 300°C in an atmospheric environment were obtained by depositing a composite gradient transition layer of pure nickel layer to pure chromium layer on an oxygen-free copper substrate in the present invention and then depositing an alumina coating.

[0031] Figure 9 This is a comparison chart of the thermal shock resistance of the aluminum oxide coating in the present invention.

[0032] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0033] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are merely examples, and those skilled in the art may conceive of other obvious variations.

[0034] See also Figure 1 and Figure 2 In one embodiment of the present invention, a method for preparing a heat-shock-resistant aluminum oxide coating is provided, comprising the following steps:

[0035] Step S11, the oxygen-free copper substrate after being bombarded and cleaned by a gas ion source is sent into a first coating process chamber, and dual targets are used for synchronous sputtering by pulsed DC magnetron sputtering to form a nickel-chromium composite gradient transition layer transitioning from a pure nickel layer to a pure chromium layer on the surface of the oxygen-free copper substrate, wherein as the deposition process proceeds, the sputtering voltage of the nickel target is gradually reduced, and the sputtering voltage of the chromium target is synchronously gradually increased;

[0036] Specifically, in step S11, the contact surface of the nickel-chromium composite gradient transition layer with the oxygen-free copper substrate is a pure nickel layer, and the contact surface with the aluminum oxide coating is a pure chromium layer.

[0037] Furthermore, in step S11, the thickness of the nickel-chromium composite gradient transition layer is 0.5-2 μm, the sputtering voltage of the nickel target is gradually reduced from a preset voltage to 0V, and the sputtering voltage of the chromium target is correspondingly gradually increased from 0V to a preset voltage.

[0038] It should be noted that in step S11, the oxygen-free copper substrate is fixed on a substrate rack, and the substrate rack is provided with a pulse bias power supply for applying a negative bias voltage to the oxygen-free copper substrate and a heating device for heating the oxygen-free copper substrate.

[0039] Specifically, the pulse bias voltage range is 50-300 V, and the heating temperature range is 25-300° C. The purpose is to improve the directionality of the sputtered particles of the magnetron sputtering cathode and promote the mutual diffusion of the nickel and chromium composite gradient transition layer with each other and with the substrate.

[0040] Step S12, transferring the oxygen-free copper substrate with the nickel and chromium composite gradient transition layer deposited on the surface to a cooling chamber, and cooling it to a preset temperature;

[0041] Preferably, in step S12, the preset temperature is 25-75°C.

[0042] In step S13, the cooled oxygen-free copper substrate with the nickel and chromium composite gradient transition layer deposited on the surface is transferred to a second coating process chamber and sputtered by medium-frequency magnetron sputtering to deposit an aluminum oxide coating on the surface of the nickel and chromium composite gradient transition layer.

[0043] Preferably, in step S13, the voltage of magnetron sputtering is 400-600 V, and the thickness of the aluminum oxide coating is 2-6 μm.

[0044] It should be noted that the two sputtering cathodes in the first coating process chamber are mounted on a first translation track, and the height of the magnetron sputtering distance from the surface to be coated is consistent;

[0045] The two sputtering cathodes in the second coating process chamber are mounted on a second translation track, and the height of the magnetron sputtering cathodes from the surface to be coated is consistent;

[0046] The distance between each sputtering cathode and the surface to be coated is 8~15 cm.

[0047] Specifically, in the present invention, the structure of each sputtering cathode is a rectangular cathode. When sputtering a large-area substrate, the sputtering cathode will reciprocate within a certain range to ensure the uniformity of the film layer, avoiding the problem of uneven film thickness caused by the sputtering gradient of the fixed cathode.

[0048] Furthermore, before step S11, the method for preparing the heat-shock-resistant alumina coating further includes:

[0049] A soft-contact electric forklift is used to transport the oxygen-free copper substrate to the positioning platform, and the robot automatically sends the oxygen-free copper substrate to the cleaning equipment for ultrasonic cleaning and drying;

[0050] The dried oxygen-free copper substrate is automatically transferred to the vacuum chamber by a robot and bombarded and cleaned by a gas ion source.

[0051] Specifically, the gas ion source is a linear anode ion source, the working gas is argon, the voltage is adjustable from 800 to 1200 V, 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 activates the substrate and improves the film-substrate bonding.

[0052] It should be noted that, in this application, when the vacuum degree of the cavity is 8×10 -4 ~1×10 -3 The coating process can begin within the Pa range. After the first set of oxygen-free copper substrates, which have completed the deposition of the pure nickel to pure chromium composite gradient transition layer, enter 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 the deposition of the nickel-chromium composite gradient transition layer. Therefore, the sputtering cathode does not need to stop working, improving sputtering efficiency.

[0053] In summary, the present invention reduces the gradient of the thermal expansion coefficient between the oxygen-free copper substrate and the alumina coating by depositing a composite gradient transition layer transitioning from a pure nickel layer to a pure chromium layer on the surface of the oxygen-free copper substrate, and reduces the accumulation of thermal stress at the interface between the two during temperature rise and fall, thereby improving the thermal shock resistance of the alumina coating.

[0054] First, preprocessing

[0055] In a Class 1000 dust-free workshop, a soft-contact electric forklift is used to transfer the oxygen-free copper substrate to the positioning stand. After the substrate is adjusted to the appropriate position, a forklift is used to transfer the substrate to the cleaning equipment.

[0056] 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.

[0057] In order to prevent the oxygen-free copper 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.

[0058] Second, nickel and chromium composite gradient transition layer deposition

[0059] Multiple groups of substrates enter the storage chamber - vacuum is evacuated - 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 - adjust the angle and height of the sputtering cathode to deposit a nickel and chromium composite gradient transition layer - the first group of substrates undergoes pulsed DC magnetron sputtering cathode co-sputtering to deposit a nickel and chromium composite gradient 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 nickel and chromium composite gradient transition layer deposition, and at the same time the third group of substrates enters the ion source chamber - repeat the above steps until all substrates complete the nickel and chromium composite gradient transition layer deposition.

[0060] Third, alumina coating deposition

[0061] After the first group of substrates are cooled in the cooling chamber, they enter the second coating process chamber - adjust the angle and height of the sputtering cathode to deposit the aluminum oxide coating - the first group of substrates undergo medium-frequency magnetron sputtering to deposit the aluminum oxide coating - after the preset time is reached, they are transported to the storage room for cooling, and then the second group of substrates enter the second coating process chamber for deposition of the aluminum oxide coating - repeat the above steps until all substrates containing the transition layer have completed the deposition of the aluminum oxide coating.

[0062] Fourth, finished product testing

[0063] The finished products are subjected to rapid temperature rise and fall cycle tests to check the surface integrity of the alumina coating of the tested samples, whether there are cracks or wrinkles, etc., to determine whether they meet the standards. After passing the inspection, they are transferred to a nitrogen-protected storage box.

[0064] See also Figures 3 to 5 In another embodiment of the present invention, a method for preparing a heat-shock-resistant aluminum oxide coating is provided. The experimental contents are as follows:

[0065] An oxygen-free copper substrate measuring 20×20×2mm was pretreated and then sent to a gas ion source chamber for ion bombardment cleaning. The substrate was then transferred to the coating chamber and co-sputtered with a nickel-chromium composite gradient transition layer using a pulsed DC magnetron sputtering cathode. The substrate heating temperature was set to 150°C and the pulse bias voltage was set to -100V. Since the sputtering voltage is generally not less than 300V regardless of the sputtering power in magnetron sputtering, otherwise normal discharge will not occur. Therefore, the rectangular cathode nickel target voltage was set to 700V, 600V, 500V, 400V, 300V, and 0V, and the corresponding chromium target voltage was set to 0V, 300V, 400V, 500V, 600V, and 700V. Sputtering was continued for 5 minutes at each voltage setting, and the nickel-chromium composite gradient transition layer formed on the surface was approximately 1μm thick. After deposition, the substrate was cooled to 30°C and then reactively sputtered for 6 hours at 500V using a medium-frequency twin cathode power supply. This deposited an aluminum oxide coating approximately 4μm thick on the substrate surface. The finished product was then subjected to thermal shock resistance testing.

[0066] See also Figure 3 The substrate holder where the oxygen-free copper substrate is located can be loaded with a negative pulse bias voltage and is equipped with a heating device. Combined with the pulsed DC power supply used in the rectangular cathode co-sputtering deposition of nickel and chromium composite gradient transition layer, it can improve the directionality of the magnetron sputtering cathode sputtering particles and promote the mutual diffusion between the oxygen-free copper substrate and the nickel and chromium composite gradient transition layer, thereby improving the deposition quality of the nickel and chromium composite gradient transition layer and the film-substrate bonding strength.

[0067] See also Figure 4The aluminum oxide coating is deposited using a medium-frequency power supply and a rectangular twin cathode. This combination effectively reduces target poisoning during coating preparation and stabilizes the sputtering process. The rectangular twin cathode and medium-frequency power supply are mounted on a translational track that reciprocates during the coating process, improving the uniformity of the deposited coating on large substrates.

[0068] See also Figures 6 to 9 After a single rapid temperature rise and fall test from room temperature to 300°C, the aluminum oxide coating directly deposited on the oxygen-free copper substrate exhibited large-scale peeling, exposing the oxygen-free copper substrate. This was corroborated by the copper element signal displayed by the surface element characterization at the coating peeling location. Furthermore, after five rapid temperature rise and fall tests from room temperature to 300°C, the aluminum oxide coating prepared by depositing a nickel and chromium composite gradient transition layer on the oxygen-free copper substrate showed signs of delamination at some points. After 20 tests, the aluminum oxide coating became very incomplete, with the delamination area expanding, exposing the underlying transition layer or oxygen-free copper substrate. This was also confirmed by the surface element characterization near the aluminum oxide coating peeling site, which revealed signals of chromium, nickel, and copper underneath.

[0069] The aluminum oxide coating prepared after depositing a composite gradient transition layer from pure nickel to pure chromium on the surface of an oxygen-free copper substrate remained intact after 100 rapid temperature rise and fall cycles from room temperature to 300°C, with no signs of coating peeling. Elemental analysis of the surface aluminum oxide coating showed that it was almost entirely composed of aluminum and oxygen elements, and the atomic proportion of chromium, nickel and copper substrate in the underlying transition layer was almost negligible, which also confirmed the integrity of the surface aluminum oxide coating and indicated that the aluminum oxide coating deposited on the nickel-chromium composite gradient transition layer had excellent heat shock resistance.

[0070] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions merely illustrate the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a heat-shock-resistant alumina coating, characterized in that: The following steps are involved: Step S11, the oxygen-free copper substrate after being bombarded and cleaned by a gas ion source is sent into a first coating process chamber, and dual targets are used for synchronous sputtering by pulsed DC magnetron sputtering to form a nickel-chromium composite gradient transition layer transitioning from a pure nickel layer to a pure chromium layer on the surface of the oxygen-free copper substrate, wherein as the deposition process proceeds, the sputtering voltage of the nickel target is gradually reduced, and the sputtering voltage of the chromium target is synchronously gradually increased; The thickness of the nickel and chromium composite gradient transition layer is 0.5-2 μm, the sputtering voltage of the nickel target is gradually reduced from a preset voltage to 0V, and the sputtering voltage of the chromium target is correspondingly gradually increased from 0V to a preset voltage; The contact surface of the nickel and chromium composite gradient transition layer with the oxygen-free copper substrate is a pure nickel layer, and the contact surface with the aluminum oxide coating is a pure chromium layer; Step S12, transferring the oxygen-free copper substrate with the nickel and chromium composite gradient transition layer deposited on the surface to a cooling chamber, and cooling it to a preset temperature; In step S13, the cooled oxygen-free copper substrate with the nickel and chromium composite gradient transition layer deposited on the surface is transferred to a second coating process chamber and sputtered by medium-frequency magnetron sputtering to deposit an aluminum oxide coating on the surface of the nickel and chromium composite gradient transition layer.

2. The method for preparing the heat-shock-resistant alumina coating according to claim 1, wherein: In step S11, the oxygen-free copper substrate is fixed on a substrate frame, and the substrate frame is provided with a pulse bias power supply for applying a negative bias voltage to the oxygen-free copper substrate and a heating device for heating the oxygen-free copper substrate.

3. The method for preparing the heat-shock-resistant alumina coating according to claim 2, wherein: The pulse bias voltage range is 50~300V, and the heating temperature range is 25~300℃.

4. The method for preparing a heat-shock-resistant alumina coating according to claim 1, wherein: Before step S11, the method for preparing the heat-shock-resistant alumina coating further includes: A soft-contact electric forklift is used to transport the oxygen-free copper substrate to the positioning platform, and the robot automatically sends the oxygen-free copper substrate to the cleaning equipment for ultrasonic cleaning and drying; The dried oxygen-free copper substrate is automatically transferred to the vacuum chamber by a robot and bombarded and cleaned by a gas ion source.

5. The method for preparing the heat-shock-resistant alumina coating according to claim 4, characterized in that: The gas ion source was a linear anode ion source, the working gas was argon, the voltage was adjustable in the range of 800–1200 V, and the bombardment time was 10–30 min.

6. The method for preparing a heat-shock-resistant aluminum oxide coating according to claim 1, wherein: In step S12, the preset temperature is 25-75°C.

7. The method for preparing a heat-shock-resistant aluminum oxide coating according to claim 1, wherein: In step S13 , the voltage of the magnetron sputtering is 400-600 V, and the thickness of the aluminum oxide coating is 2-6 μm.

8. The method for preparing a heat-shock-resistant alumina coating according to any one of claims 1 to 7, characterized in that: The two sputtering cathodes in the first coating process chamber are mounted on a first translation track, and the height of the magnetron sputtering cathodes from the surface to be coated is consistent; The two sputtering cathodes in the second coating process chamber are mounted on a second translation track, and the height of the magnetron sputtering cathodes from the surface to be coated is consistent; The distance between each sputtering cathode and the surface to be coated is 8~15 cm.

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