A method for producing high quality metal carbide thin films on diamond heat sinks

Abstract

The application discloses a method for preparing high-quality metal carbide film on a diamond heat sink, which comprises the following steps: (1) performing grinding, polishing, cleaning and baking pretreatment on the surface of a single crystal diamond sheet; (2) coating a nano-thickness titanium carbide film on the single crystal diamond sheet after the pretreatment by using a magnetron sputtering method; (3) performing quartz tube sealing treatment on the single crystal diamond sheet coated with the titanium carbide film and then performing low-temperature annealing; and (4) reducing the temperature to room temperature by using an extremely low cooling rate and then taking out the diamond heat sink with a surface provided with the high-quality metal carbide film. The method is used for coating the titanium carbide film on the surface of the diamond by using the magnetron sputtering method, and the crystallinity of the titanium carbide film is improved by combining the low-temperature annealing and the low-speed cooling, so that the problems of the titanium carbide film cracking and falling off caused by high thermal stress and the surface roughness caused by grain growth are effectively avoided, the high-quality metal carbide film is obtained, and the demand of the subsequent metallization of the diamond heat sink is met.

Description

Technical Field

[0001] This invention belongs to the field of thermal management materials technology, specifically relating to a method for preparing high-quality metal carbide films on diamond heat sinks. Background Technology

[0002] Diamond is chemically very stable, but as a heat sink, it has extremely poor direct adhesion to most solders, making it difficult to form strong physical or chemical bonds. Therefore, the diamond surface needs to be metallized first. By plating with metals such as silver, copper, or gold, an active metal layer can be formed on the diamond surface, enhancing its adhesion to subsequent soldering materials (such as solder or silver paste) and ensuring a reliable connection between the heat sink and the device or substrate.

[0003] However, the chemical inertness of diamond leads to poor bonding strength at the interface with metal layers such as silver, copper, and gold, and there is also a severe phonon mismatch between diamond and these metal layers. To address these issues, an effective solution is to first deposit a thin layer of metal such as titanium or chromium onto the diamond surface, then form a carbide layer on the diamond surface through high-temperature annealing above 800°C, and finally deposit a metal layer (silver, copper, gold, etc.) onto the diamond surface (a diamond heat sink substrate for integrated circuits and its preparation method, application number 2023116443210). However, the carbide transition layer obtained using this method is prone to problems such as film cracking and detachment due to high thermal stress, and surface roughness due to grain growth, making it impossible to obtain a high-quality carbide transition layer and hindering the subsequent metallization process of the diamond heat sink. Summary of the Invention

[0004] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for preparing high-quality metal carbide thin films on diamond heat sinks. This method employs magnetron sputtering to deposit a nanometer-thick titanium carbide thin film on the diamond surface, followed by low-temperature annealing and low-speed cooling. This improves the crystallinity of the titanium carbide thin film and effectively avoids problems such as cracking and detachment of the titanium carbide thin film caused by high thermal stress, and surface roughness caused by grain growth. This yields a high-quality metal carbide thin film, solving the problems of surface roughness, easy cracking, and detachment of existing diamond surface carbide transition layers. To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for preparing high-quality metal carbide thin films on diamond heat sinks, characterized in that the method includes the following steps: Step 1: Grind, polish and clean the surface of the millimeter-sized single-crystal diamond sheet, and then perform vacuum baking treatment to obtain the pre-treated single-crystal diamond sheet; the temperature of the vacuum baking treatment is 150℃~400℃. Step 2: Argon ion bombardment of titanium carbide target material is performed using magnetron sputtering to deposit a titanium carbide thin film with a nanometer-thickness on the pretreated single-crystal diamond sheet in Step 1; the magnetron sputtering method uses a power of 200W~500W and the thickness of the titanium carbide thin film is 20nm~200nm. Step 3: The single-crystal diamond sheet coated with a nano-thickness titanium carbide film in Step 2 is sealed in a quartz tube. During the sealing process, a vacuum is drawn and hydrogen is introduced, followed by low-temperature annealing. The temperature of the low-temperature annealing is 300℃~500℃, and the holding time is 10h~20h. Step 4: After the low-temperature annealing in Step 3 is completed, the temperature is reduced to room temperature at an extremely low cooling rate, and the diamond heat sink with a high-quality metal carbide film on the surface is removed; the extremely low cooling rate is 0.1℃ / min~0.5℃ / min.

[0005] The method for preparing high-quality metal carbide films on diamond heat sinks, as described above, is characterized in that the grinding process in step one involves sequential grinding with diamond suspensions of 3 μm and 0.5 μm particle sizes, and the cleaning process includes acetone, ethanol solution cleaning, and plasma cleaning. The introduction of plasma cleaning on top of conventional solvent cleaning achieves atomically clean surfaces, eliminates the amorphous layer caused by grinding and polishing, and the CO bonds formed during plasma cleaning help improve the interfacial adhesion between the diamond and the film.

[0006] The method described above for preparing high-quality metal carbide thin films on diamond heat sinks is characterized in that the magnetron sputtering method in step two employs a vacuum degree lower than 10. 5 Pa, during the process, argon gas is introduced at a flow rate of 30 sccm to 50 sccm. This argon flow rate takes into account indicators such as plasma stability, sputtering efficiency, and thin film quality.

[0007] The method described above for preparing high-quality metal carbide films on diamond heat sinks is characterized in that, in step three, the vacuum level is reduced to below 10. 5 Pa, wherein the hydrogen is charged to 0.8 atmospheres. By charging the quartz tube with hydrogen at 0.8 atmospheres, a high-density reducing atmosphere is provided, and during low-temperature annealing heat treatment, the excessive hydrogen pressure caused by temperature rise can be avoided, which could lead to quartz tube rupture and hydrogen leakage.

[0008] Compared with the prior art, the present invention has the following advantages: 1. This invention uses magnetron sputtering to deposit a titanium carbide thin film on the surface of diamond, and then combines it with low-temperature annealing to release the thermal stress in the titanium carbide thin film, while improving the crystallinity of the titanium carbide thin film. This avoids problems such as cracking or peeling of the titanium carbide thin film caused by thermal stress, as well as surface roughness caused by grain growth. In this way, a high-quality metal carbide thin film is obtained on the surface of diamond heat sink, laying the foundation for subsequent metallization of diamond heat sink.

[0009] 2. The present invention uses low-temperature annealing, which greatly reduces the risk of oxidation on the surface of titanium carbide film and diamond, further improves the quality of metal carbide film, and is beneficial to the protection of heat dissipation structure and heat dissipation performance.

[0010] 3. In the cooling process after low-temperature annealing, the present invention uses an extremely low cooling rate to reduce the temperature to room temperature, which greatly improves the problems of cracking or peeling of titanium carbide films and diamonds caused by thermal stress, and further improves the quality of metal carbide films.

[0011] 4. The titanium carbide thin film deposited on the diamond surface by magnetron sputtering in this invention has a melting point as high as 3160℃. Furthermore, titanium carbide can only undergo grain coarsening in the temperature range of 1800℃ to 2200℃. Therefore, by controlling the low-temperature annealing temperature to 300℃ to 500℃, this invention improves the crystal quality of the titanium carbide thin film without causing significant grain growth due to annealing. As a result, the titanium carbide film has high crystal quality and extremely low surface roughness, ensuring excellent quality.

[0012] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0013] Figure 1 This is a SEM image of the high-quality metal carbide film prepared on the surface of a diamond heat sink in Example 1 of the present invention.

[0014] Figure 2 This is an AFM morphology image of the high-quality metal carbide film prepared on the surface of a diamond heat sink in Example 1 of the present invention.

[0015] Figure 3 This is a SEM image of the metal carbide film prepared on the surface of a diamond heat sink in Comparative Example 1 of the present invention.

[0016] Figure 4 This is an AFM morphology image of the metal carbide film prepared on the surface of a diamond heat sink in Comparative Example 1 of the present invention. Detailed Implementation

[0017] Example 1 This embodiment includes the following steps: Step 1: Grinding, polishing, and cleaning the surface of millimeter-sized single-crystal diamond wafers with a diameter greater than 2 mm and a thickness of 1 mm, followed by vacuum baking to obtain pre-treated single-crystal diamond wafers; the grinding process sequentially uses diamond suspensions with particle sizes of 3 μm and 0.5 μm; the cleaning includes acetone, ethanol solution cleaning, and plasma cleaning; the vacuum baking temperature is 300℃. Step 2: Argon ion bombardment of the titanium carbide target is performed using magnetron sputtering to deposit a 100 nm thick titanium carbide thin film onto the pretreated single-crystal diamond wafer from Step 1. The magnetron sputtering method uses a power of 400 W and a vacuum level below 10. 5 Pa, during the process, argon gas is introduced at a flow rate of 40 sccm; Step 3: Seal the single-crystal diamond wafer coated with titanium carbide film from Step 2 into a quartz tube. During the sealing process, evacuate the tube to a vacuum level below 10. 5 Pa was charged with hydrogen to 0.8 atmospheres, and then subjected to low-temperature annealing; the low-temperature annealing temperature was 400℃ and the holding time was 15h. Step 4: After the low-temperature annealing in Step 3 is completed, the temperature is reduced to room temperature at an extremely low cooling rate of 0.3℃ / min, and the diamond heat sink with a high-quality metal carbide film on the surface is removed.

[0018] Figure 1 This is a SEM image of the high-quality metal carbide film prepared on the surface of a diamond heat sink in this embodiment. Figure 1 It can be seen that the surface of the metal carbide film is free from cracking and peeling, and has a high-quality surface.

[0019] Figure 2 This is an AFM morphology image of the high-quality metal carbide film prepared on the surface of a diamond heat sink in this embodiment. Figure 2 It can be seen that the surface roughness of this metal carbide film is extremely low, R q It has a surface size of less than 2nm and a high quality.

[0020] Comparative Example 1 This comparative example includes the following steps: Step 1: Grinding, polishing, and cleaning the surface of millimeter-sized single-crystal diamond wafers with a diameter greater than 2 mm and a thickness of 1 mm, followed by vacuum baking to obtain pre-treated single-crystal diamond wafers; the grinding process sequentially uses diamond suspensions with particle sizes of 3 μm and 0.5 μm; the cleaning includes acetone, ethanol solution cleaning, and plasma cleaning; the vacuum baking temperature is 300℃. Step 2: Argon ion bombardment of the titanium carbide target is performed using magnetron sputtering to deposit a 100 nm thick titanium carbide thin film onto the pretreated single-crystal diamond wafer from Step 1. The magnetron sputtering method uses a power of 400 W and a vacuum level below 10. 5 Pa, during the process, argon gas is introduced at a flow rate of 40 sccm; Step 3: Seal the single-crystal diamond wafer coated with titanium carbide film from Step 2 into a quartz tube. During the sealing process, evacuate the tube to a vacuum level below 10. 5 Pa was charged with hydrogen to 0.8 atmospheres, and then subjected to high-temperature annealing; the high-temperature annealing temperature was 800℃, and the holding time was 10 min. Step 4: After the low-temperature annealing in Step 3 is completed, the temperature is reduced to room temperature at an extremely low cooling rate of 0.3℃ / min, and the diamond heat sink with a metal carbide film on its surface is removed.

[0021] Figure 3 The images shown are SEM images of the metal carbide films prepared on the diamond heat sink surface in this comparative example. Figure 3 It can be seen that the metal carbide film prepared by the traditional high-temperature annealing method has cracking on the surface and poor surface quality.

[0022] Figure 4 The image shows the AFM morphology of the metal carbide film prepared on the diamond heat sink surface in this comparative example. Figure 4 It can be seen that the metal carbide film prepared by the traditional high-temperature annealing method has a higher surface roughness, R q Surface quality is poor when the size is greater than 5nm.

[0023] Example 2 This embodiment includes the following steps: Step 1: The surface of a millimeter-sized single-crystal diamond sheet with a diameter greater than 2 mm and a thickness of 1 mm is ground, polished, and cleaned, and then vacuum baked to obtain a pre-treated single-crystal diamond sheet. The grinding process uses diamond suspensions with particle sizes of 3 μm and 0.5 μm in sequence. The cleaning includes acetone, ethanol solution cleaning, and plasma cleaning. The vacuum baking temperature is 150℃. Step 2: Argon ion bombardment of the titanium carbide target is performed using magnetron sputtering to deposit a 20 nm thick titanium carbide thin film onto the pretreated single-crystal diamond wafer from Step 1. The magnetron sputtering method uses a power of 200 W and a vacuum level below 10. 5 Pa, during the process, argon gas is introduced at a flow rate of 30 sccm; Step 3: Seal the single-crystal diamond wafer coated with titanium carbide film from Step 2 into a quartz tube. During the sealing process, evacuate the tube to a vacuum level below 10. 5 Pa was charged with hydrogen to 0.8 atmospheres, and then subjected to low-temperature annealing; the low-temperature annealing temperature was 300℃, and the holding time was 10h. Step 4: After the low-temperature annealing in Step 3 is completed, the temperature is reduced to room temperature at an extremely low cooling rate of 0.1℃ / min, and the diamond heat sink with a high-quality metal carbide film on the surface is removed.

[0024] Example 3 This embodiment includes the following steps: Step 1: The surface of a millimeter-sized single-crystal diamond sheet with a diameter greater than 2 mm and a thickness of 1 mm is ground, polished, and cleaned, and then vacuum baked to obtain a pre-treated single-crystal diamond sheet. The grinding process uses diamond suspensions with particle sizes of 3 μm and 0.5 μm in sequence. The cleaning includes acetone, ethanol solution cleaning, and plasma cleaning. The vacuum baking temperature is 400℃. Step 2: Argon ion bombardment of the titanium carbide target is performed using magnetron sputtering to deposit a 200 nm thick titanium carbide thin film onto the pretreated single-crystal diamond wafer from Step 1. The magnetron sputtering method uses a power of 500 W and a vacuum level below 10. 5 Pa, during the process, argon gas is introduced at a flow rate of 50 sccm; Step 3: Seal the single-crystal diamond wafer coated with titanium carbide film from Step 2 into a quartz tube. During the sealing process, evacuate the tube to a vacuum level below 10. 5 Pa was charged with hydrogen to 0.8 atmospheres, and then subjected to low-temperature annealing; the low-temperature annealing temperature was 500℃, and the holding time was 20h. Step 4: After the low-temperature annealing in Step 3 is completed, the temperature is reduced to room temperature at an extremely low cooling rate of 0.5℃ / min, and the diamond heat sink with a high-quality metal carbide film on the surface is removed.

[0025] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing high-quality metal carbide thin films on diamond heat sinks, characterized in that, The method includes the following steps: Step 1: Grind, polish and clean the surface of the millimeter-sized single-crystal diamond sheet, and then perform vacuum baking treatment to obtain the pretreated single-crystal diamond sheet; the temperature of the vacuum baking treatment is 150℃~400℃. Step 2: Argon ion bombardment of titanium carbide target material is performed using magnetron sputtering to deposit a titanium carbide thin film with a nanometer-thickness on the pretreated single-crystal diamond sheet in Step 1; the magnetron sputtering method uses a power of 200W to 500W and the thickness of the titanium carbide thin film is 20nm to 200nm. Step 3: The single-crystal diamond sheet coated with a nano-thickness titanium carbide film in Step 2 is sealed in a quartz tube. During the sealing process, a vacuum is drawn and hydrogen is introduced, followed by low-temperature annealing. The temperature of the low-temperature annealing is 300℃~500℃, and the holding time is 10h~20h. Step 4: After the low-temperature annealing in Step 3 is completed, the temperature is reduced to room temperature at an extremely low cooling rate, and the diamond heat sink with a high-quality metal carbide film on the surface is removed; the extremely low cooling rate is 0.1℃ / min~0.5℃ / min.

2. The method for preparing high-quality metal carbide thin films on a diamond heat sink according to claim 1, characterized in that, The grinding process in step one involves sequential grinding with diamond suspensions of 3μm and 0.5μm particle sizes. The cleaning process includes acetone, ethanol solution cleaning, and plasma cleaning.

3. The method for preparing high-quality metal carbide thin films on a diamond heat sink according to claim 1, characterized in that, The magnetron sputtering method described in step two uses a vacuum level of less than 10. -5 Pa, during the process, argon gas is introduced at a flow rate of 30 sccm to 50 sccm.

4. The method for preparing high-quality metal carbide thin films on a diamond heat sink according to claim 1, characterized in that, Step three involves evacuating the vacuum level to below 10. -5 Pa, wherein the hydrogen gas is charged to 0.8 atmospheres.

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