Preparation method of thermal shock resistant aluminum oxide coating

Abstract

A preparation method of a thermal shock resistant aluminum oxide coating comprises the following steps: feeding an oxygen-free copper substrate which is bombarded and cleaned by a gas ion source into a first coating process chamber, and carrying out synchronous sputtering by adopting double targets in a pulse direct current magnetron sputtering manner, a nickel-chromium composite gradient transition layer transited from a pure nickel layer to a pure chromium layer is formed on the surface of the oxygen-free copper substrate; the oxygen-free copper base body with the nickel and chromium composite gradient transition layer deposited on the surface is conveyed into a cooling chamber to be subjected to standing and cooling to the preset temperature; and the cooled oxygen-free copper base body with the nickel and chromium composite gradient transition layer deposited on the surface is conveyed into a second coating process cavity, sputtering is carried out in a medium-frequency magnetron sputtering mode, and the aluminum oxide coating is deposited on the surface of the nickel and chromium composite gradient transition layer. The composite gradient transition layer transited from the pure nickel layer to the pure chromium layer is deposited on the surface of the oxygen-free copper substrate, so that the change gradient of the thermal expansion coefficient between the oxygen-free copper substrate and the aluminum oxide coating is reduced, and thermal stress accumulation of the oxygen-free copper substrate and the aluminum oxide coating at the interface in the temperature rising and falling process is reduced; therefore, the thermal shock resistance of the aluminum oxide coating is improved.

Description

Technical Field

[0001] The invention relates to the technical field of material surface treatment, and 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 high. Usually, corresponding copper components are required to carry out heat exchange and cooling of the components.

[0003] Since the copper component is located in the etching chamber, it will be etched by plasma during the etching process. At present, the surface of the copper component is mainly protected by coating (preparing an etching-resistant aluminum oxide coating on the surface of the copper component). However, due to the large difference in thermal expansion coefficients 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. The accumulated huge thermal stress will cause the aluminum oxide coating to fall off and fail, making it difficult to achieve actual protective 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: Step S11, sending the oxygen-free copper substrate after gas ion source bombardment cleaning into the first coating process chamber, using dual targets to perform 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 gradually increased synchronously; 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 by standing; Step S13, transferring the cooled oxygen-free copper substrate with the nickel-chromium composite gradient transition layer deposited on the surface to a second coating process chamber, and sputtering it by medium-frequency magnetron sputtering to deposit an aluminum oxide coating on the surface of the nickel-chromium composite gradient transition layer.

[0006] Compared with the prior art, the present invention reduces the gradient of change of 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 heat shock resistance of the alumina coating.

[0007] 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.

[0008] 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.

[0009] Preferably, 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.

[0010] Preferably, the pulse bias voltage ranges from 50 to 300 V, and the heating temperature ranges from 25 to 300° C.

[0011] Preferably, before step S11, the method for preparing the heat shock resistant aluminum oxide coating further comprises: The oxygen-free copper substrate is transferred to the positioning stand by a soft-contact electric forklift, and the oxygen-free copper substrate is automatically sent to the cleaning equipment for ultrasonic cleaning and drying by a manipulator; 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.

[0012] 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.

[0013] Preferably, in step S12, the preset temperature is 25-75°C.

[0014] 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.

[0015] 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 distance 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 distance from the surface to be coated is consistent; The distance between each sputtering cathode and the surface to be coated is 8~15 cm. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is a flow chart of a method for preparing a heat-shock-resistant aluminum oxide coating; Figure 2 This is a schematic diagram of the production line process for preparing the heat shock resistant aluminum oxide coating of the present invention; Figure 3 It is a schematic diagram of co-sputtering of a sputtering cathode in a first coating process chamber of the present invention; Figure 4 It is a schematic diagram of co-sputtering of the sputtering cathode in the second coating process chamber of the present invention; Figure 5 It is a schematic diagram of the structure of the heat shock resistant aluminum oxide coating in the present invention; Figure 6 The overall appearance and surface element characterization of the aluminum oxide coating directly deposited on the oxygen-free copper substrate in the present invention after a rapid temperature rise and fall cycle from RT to 300°C in an atmospheric environment; Figure 7 The overall appearance and surface element characterization results of the aluminum oxide coating after 20 rapid temperature rise and fall cycles from RT to 300°C in an atmospheric environment after a double transition layer of nickel and chromium is deposited on the oxygen-free copper substrate of the present invention; Figure 8 The composite gradient transition layer of the oxygen-free copper substrate in the present invention is deposited with a pure nickel layer to transition to a pure chromium layer, and then an aluminum oxide coating is deposited. The overall appearance and surface element characterization results of the aluminum oxide coating after 100 rapid temperature rise and fall cycles from RT to 300°C in an atmospheric environment; Fig. 9 It is a comparison chart of the thermal shock resistance of the aluminum oxide coating in the present invention.

[0017] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0018] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0019] 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: Step S11, sending the oxygen-free copper substrate after gas ion source bombardment cleaning into the first coating process chamber, using dual targets to perform 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 gradually increased synchronously; 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.

[0020] 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.

[0021] It should be noted that, 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.

[0022] Specifically, the pulse bias voltage ranges from 50 to 300 V, and the heating temperature ranges from 25 to 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 layers with each other and with the substrate.

[0023] 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 by standing; Preferably, in step S12, the preset temperature is 25-75°C.

[0024] Step S13, transferring the cooled oxygen-free copper substrate with the nickel-chromium composite gradient transition layer deposited on the surface to a second coating process chamber, and sputtering it by medium-frequency magnetron sputtering to deposit an aluminum oxide coating on the surface of the nickel-chromium composite gradient transition layer.

[0025] 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.

[0026] It should be noted that the two sputtering cathodes in the first coating process chamber are installed on the first translation track, and the height of the magnetron sputtering distance 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 distance from the surface to be coated is consistent; The distance between each sputtering cathode and the surface to be coated is 8~15 cm.

[0027] 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.

[0028] Furthermore, before step S11, the method for preparing the heat shock resistant aluminum oxide coating further comprises: The oxygen-free copper substrate is transferred to the positioning stand by a soft-contact electric forklift, and the oxygen-free copper substrate is automatically sent to the cleaning equipment for ultrasonic cleaning and drying by a manipulator; 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.

[0029] Specifically, 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. The purpose is to remove the residual water molecule film and organic matter on the surface of the substrate to be coated after pretreatment, and to activate the substrate and improve the bonding strength of the film substrate through particle bombardment.

[0030] 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 be started within the Pa range. After the oxygen-free copper substrate of the first group that has completed the deposition of the composite gradient transition layer from pure nickel to pure chromium enters the cooling chamber, the next group of sample substrates stored in the ion source gas chamber will then enter the first coating process chamber for the deposition of the composite gradient transition layer of nickel and chromium. Therefore, the sputtering cathode does not need to stop working, which improves the sputtering efficiency.

[0031] In summary, the present invention reduces the gradient of change of 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, reduces the accumulation of thermal stress at the interface between the two during temperature rise and fall, and thus improves the heat shock resistance of the alumina coating.

[0032] First, preprocessing In the 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 a suitable position, a forklift is used to transfer the substrate to the cleaning equipment. The scanner is used to extract the product's external dimensions. The automated cleaning and transmission section adaptively adjusts the positions of the manipulator, lifting fixture, and transmission wheel according to the product's dimensions. The forklift lifts the substrate to the front section of the cleaning machine where the manipulator grabs it. The manipulator automatically transfers the substrate to the cleaning equipment for cleaning, which includes: ultrasonic liquid cleaning - 1 ultrasonic rinse - 2 ultrasonic rinses - scanning spray - clean air to remove water - vacuum dehydration - cleanliness inspection; In order to prevent the oxygen-free copper substrate from being attached by tiny particles after cleaning, this stage enters the fully automatic transfer process, including: tray splicing - tray transmission - robot grabbing - substrate rack receiving substrate - substrate rack transmission to the cleaning area in the vacuum chamber.

[0033] Second, nickel and chromium composite gradient transition layer deposition Multiple groups of substrates enter the storage chamber - evacuate - introduce working gas argon - the first group of substrates enter the ion source chamber - gas plasma surface cleaning - the first group of substrates enter the first coating process chamber, and the second group of substrates enter the ion source chamber for gas plasma cleaning - adjust the angle and height of the sputtering cathode to deposit a nickel-chromium composite gradient transition layer - the first group of substrates undergo pulsed DC magnetron sputtering cathode co-sputtering to deposit a nickel-chromium composite gradient transition layer - the first group of substrates enter the cooling chamber for static cooling, the second group of substrates enter the first coating process chamber for nickel-chromium composite gradient transition layer deposition, and at the same time the third group of substrates enter the ion source chamber - repeat the above steps until all substrates complete the nickel-chromium composite gradient transition layer deposition.

[0034] Third, alumina coating deposition 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 chamber 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.

[0035] Fourth, finished product testing 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.

[0036] 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: The oxygen-free copper substrate with a size of 20×20×2mm was pretreated and sent to the gas ion source chamber for ion bombardment cleaning after treatment. It was transferred to the coating chamber and a nickel-chromium composite gradient transition layer was co-sputtered by a pulsed DC magnetron sputtering cathode. The substrate heating temperature was set to 150°C and the pulse bias was set to -100V. Since the sputtering voltage is generally not less than 300V regardless of the sputtering power of magnetron sputtering, otherwise it cannot be discharged normally, the rectangular cathode nickel target voltage is set to 700V, 600V, 500V, 400V, 300V and 0V, and the corresponding chromium target voltage is 0V, 300V, 400V, 500V, 600V and 700V. Sputtering was performed for 5 minutes under each set of voltages, and the thickness of the nickel-chromium composite gradient transition layer formed on the surface was about 1μm. After the deposition is completed, the substrate temperature is cooled to 30°C, and the medium frequency power supply twin cathode is used for reactive sputtering at a voltage of 500V for 6 hours to deposit an aluminum oxide coating with a thickness of about 4μm on the substrate surface. The finished product is then subjected to a heat shock resistance test.

[0037] 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 the nickel-chromium composite gradient transition layer, the directionality of the magnetron sputtering cathode sputtering particles can be improved and the mutual diffusion between the oxygen-free copper substrate and the nickel-chromium composite gradient transition layer can be promoted, thereby improving the deposition quality of the nickel-chromium composite gradient transition layer and the film-substrate bonding strength.

[0038] See also Figure 4 The power supply used for depositing aluminum oxide coating is a medium frequency power supply, and the sputtering cathode is a rectangular twin cathode. The medium frequency power supply combined with the twin cathode can effectively reduce the target poisoning during coating preparation and effectively stabilize the sputtering state. The rectangular twin cathode and the medium frequency power supply are installed on a translation track, which can slide back and forth along the track during the coating process to improve the uniformity of the deposition coating on a large area substrate.

[0039] See also Figures 6 to 9 After a rapid temperature rise and fall cycle test from room temperature to 300℃, the aluminum oxide coating directly deposited on the oxygen-free copper substrate showed a large area of ​​detachment, exposing the oxygen-free copper substrate. The copper element signal shown in the characterization of the surface elements at the coating detachment position also confirmed this fact; the aluminum oxide coating prepared by depositing a nickel and chromium composite gradient transition layer on the surface of the oxygen-free copper substrate showed signs of delamination at some points after 5 rapid temperature rise and fall cycles from room temperature to 300℃. After 20 tests, the aluminum oxide coating on the surface became very incomplete, and the delamination area expanded, exposing the underlying transition layer or oxygen-free copper substrate. The surface elements near the detachment site of the aluminum oxide coating showed signals of chromium, nickel and copper underneath, which also confirmed this result. The alumina 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, and no signs of coating shedding were found. Elemental analysis of the surface alumina coating showed that it was almost entirely 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 alumina coating, indicating that the alumina coating deposited on the nickel-chromium composite gradient transition layer has excellent heat shock resistance.

[0040] 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 only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a heat-shock-resistant aluminum oxide coating, characterized in that: The following steps are involved: Step S11, sending the oxygen-free copper substrate after gas ion source bombardment cleaning into the first coating process chamber, using dual targets to perform 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 gradually increased synchronously; 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 by standing; Step S13, transferring the cooled oxygen-free copper substrate with the nickel-chromium composite gradient transition layer deposited on the surface to a second coating process chamber, and sputtering it by medium-frequency magnetron sputtering to deposit an aluminum oxide coating on the surface of the nickel-chromium composite gradient transition layer.

2. The method for preparing the heat-shock-resistant aluminum oxide coating according to claim 1, characterized in that: In step S11, the contact surface between the nickel and chromium composite gradient transition layer and the oxygen-free copper substrate is a pure nickel layer, and the contact surface between the nickel and chromium composite gradient transition layer and the aluminum oxide coating is a pure chromium layer.

3. The method for preparing the heat-shock-resistant aluminum oxide coating according to claim 2, characterized in that: 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.

4. The method for preparing the heat-shock-resistant aluminum oxide coating according to claim 1, characterized in that: 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.

5. The method for preparing the heat-shock-resistant aluminum oxide coating according to claim 4, characterized in that: The pulse bias voltage range is 50~300V, and the heating temperature range is 25~300℃.

6. The method for preparing the heat-shock-resistant aluminum oxide coating according to claim 1, characterized in that: Before step S11, the method for preparing the heat-shock-resistant aluminum oxide coating further includes: The oxygen-free copper substrate is transferred to the positioning stand by a soft-contact electric forklift, and the oxygen-free copper substrate is automatically sent to the cleaning equipment for ultrasonic cleaning and drying by a manipulator; 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.

7. The method for preparing the heat-shock-resistant aluminum oxide coating according to claim 6, characterized in that: 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.

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

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

10. The method for preparing a heat-shock-resistant aluminum oxide coating according to any one of claims 1 to 9, 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 distance 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 distance 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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