Method for preparing high-quality metal carbide film on diamond heat sink

Abstract

The invention discloses a method for preparing a high-quality metal carbide film on a diamond heat sink. The method comprises the following steps: 1, grinding, polishing, cleaning and baking the surface of a single crystal diamond sheet; secondly, a titanium carbide film with the nanoscale thickness is plated on the pretreated single crystal diamond sheet through a magnetron sputtering method; 3, performing quartz tube sealing treatment on the monocrystal diamond sheet plated with the titanium carbide film, and then performing low-temperature annealing; and fourthly, the temperature is reduced to the room temperature at the extremely low cooling rate, and the diamond heat sink with the high-quality metal carbide film on the surface is taken out and obtained. According to the method, the titanium carbide film is plated on the surface of the diamond through the magnetron sputtering method, low-temperature annealing and low-speed cooling are combined, the crystallinity of the titanium carbide film is improved, the problems that the titanium carbide film cracks and falls off due to high thermal stress, the surface is rough due to grain growth and the like are effectively solved, and the high-quality metal carbide film is obtained; and the requirement of subsequent metallization of the diamond heat sink is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal management materials, and in particular relates to a method for preparing a high-quality metal carbide film on a diamond heat sink. Background Art

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

[0003] However, the chemical inertness of diamond leads to the problem of poor bonding strength at the interface formed between it and metal layers such as silver, copper, and gold, and there is also a serious problem of phonon mismatch between diamond and metal layers such as silver, copper, and gold. In order to solve the above problems, an effective solution is to first coat a thin layer of metal such as titanium or chromium on the surface of the diamond, and then form a carbide layer on the surface of the diamond by high-temperature annealing above 800°C, and finally coat the metal layer (silver, copper, gold, etc.) on the surface of the diamond (a diamond heat dissipation substrate for integrated circuits and its preparation method, application number 2023116443210). However, the carbide transition layer obtained using the above method is prone to problems such as film cracking and shedding caused by high thermal stress, and surface roughness caused by grain growth. It is impossible to obtain a high-quality carbide transition layer, which is not conducive to the subsequent metallization process of the diamond heat sink. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the above-mentioned existing technologies and provide a method for preparing high-quality metal carbide films on diamond heat sinks. This method uses magnetron sputtering to deposit a nanometer-thick titanium carbide film on the diamond surface. This method then performs low-temperature annealing and slow cooling to improve the crystallinity of the titanium carbide film. It also effectively avoids problems such as cracking and shedding of the titanium carbide film caused by high thermal stress, and surface roughness caused by grain growth. This method produces a high-quality metal carbide film, resolving the existing problems of rough, cracking, and shedding of the carbide transition layer on the diamond surface.

[0005] To solve the above technical problems, the present invention adopts a technical solution: a method for preparing a high-quality metal carbide film on a diamond heat sink, characterized in that the method comprises the following steps:

[0006] Step 1: grinding, polishing and cleaning the surface of a millimeter-sized single-crystal diamond sheet, and then performing a vacuum baking treatment to obtain a pre-treated single-crystal diamond sheet; the vacuum baking treatment temperature is 150° C. to 400° C.;

[0007] Step 2: Using magnetron sputtering to bombard the titanium carbide target with argon ions, a titanium carbide film with a nanometer thickness is plated on the single crystal diamond sheet pretreated in step 1; the power used in the magnetron sputtering method is 200W to 500W, and the thickness of the titanium carbide film is 20nm to 200nm;

[0008] Step 3: The single crystal diamond sheet coated with a nanometer-thick titanium carbide film in Step 2 is sealed in a quartz tube, vacuumed and filled with hydrogen during the sealing process, and then subjected to low-temperature annealing; the low-temperature annealing temperature is 300° C. to 500° C., and the holding time is 10 h to 20 h;

[0009] Step 4: After the low-temperature annealing in step 3 is completed, the diamond heat sink is cooled to room temperature at an extremely low cooling rate, and a high-quality metal carbide film is obtained on the surface; the extremely low cooling rate is 0.1°C / min to 0.5°C / min.

[0010] The aforementioned method for preparing a high-quality metal carbide film on a diamond heat sink is characterized by the following steps: the grinding process in step 1 is performed sequentially using diamond suspensions with particle sizes of 3 μm and 0.5 μm, and the cleaning process includes acetone, ethanol solution cleaning, and plasma cleaning. Plasma cleaning is introduced in addition to conventional solvent cleaning to achieve an atomically clean surface, eliminating the amorphous layer caused by grinding and polishing. Furthermore, the CO bonds formed during plasma cleaning help improve the interfacial bonding between the diamond and the coating.

[0011] The above method for preparing high-quality metal carbide film on diamond heat sink is characterized in that the vacuum degree used in the magnetron sputtering method in step 2 is lower than 10 -5 Pa, argon gas is introduced during the process 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 film quality.

[0012] The above method for preparing a high-quality metal carbide film on a diamond heat sink is characterized in that the vacuum in step 3 is evacuated to a vacuum degree of less than 10 -5 By filling the quartz tube with 0.8 atmospheres of hydrogen, a high-density reducing atmosphere is provided, and during the low-temperature annealing heat treatment, the quartz tube is prevented from being cracked and leaking due to excessive hydrogen pressure caused by heating.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1. The present invention adopts magnetron sputtering to coat a titanium carbide film on the surface of diamond, and subsequently combines it with low-temperature annealing to release the thermal stress in the titanium carbide film, while improving the crystallinity of the titanium carbide film, avoiding the cracking or falling off of the titanium carbide film caused by thermal stress, and the surface roughness caused by grain growth. In this way, a high-quality metal carbide film is obtained on the surface of the diamond heat sink, laying the foundation for the subsequent metallization of the diamond heat sink.

[0015] 2. The present invention adopts low-temperature annealing, which greatly reduces the risk of oxidation of the titanium carbide film and the diamond surface, further improves the quality of the metal carbide film, and is beneficial to the protection of the heat dissipation structure and heat dissipation performance.

[0016] 3. The present invention adopts an extremely low cooling rate to room temperature during the cooling process after low-temperature annealing, which greatly improves the problems of film cracking or shedding caused by thermal stress of titanium carbide film and diamond, and further improves the quality of metal carbide film.

[0017] 4. The melting point of the titanium carbide film coated on the diamond surface by magnetron sputtering in the present invention is 3160°C, and titanium carbide may only undergo grain coarsening in the temperature range of 1800°C to 2200°C. Therefore, the present invention controls the temperature of low-temperature annealing to 300°C to 500°C, thereby improving the crystallization quality of the titanium carbide film and preventing the titanium carbide film from undergoing significant grain growth due to annealing. As a result, the titanium carbide film has high crystallization quality and extremely low surface roughness, ensuring excellent quality.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a SEM morphology image of the high-quality metal carbide film prepared on the surface of the diamond heat sink in Example 1 of the present invention.

[0020] Figure 2 This is an AFM morphology image of the high-quality metal carbide film prepared on the surface of the diamond heat sink in Example 1 of the present invention.

[0021] Figure 3 This is a SEM morphology image of the metal carbide film prepared on the surface of the diamond heat sink in Comparative Example 1 of the present invention.

[0022] Figure 4 This is an AFM morphology image of the metal carbide film prepared on the surface of the diamond heat sink in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0023] Example 1

[0024] This embodiment includes the following steps:

[0025] Step 1: Grinding, polishing, and cleaning the surface of a millimeter-sized single-crystal diamond sheet with a sheet diameter greater than 2 mm and a thickness of 1 mm, and then performing a vacuum baking treatment to obtain a pretreated single-crystal diamond sheet; the grinding process sequentially uses diamond suspensions with particle sizes of 3 μm and 0.5 μm for grinding, and the cleaning includes acetone, ethanol solution cleaning, and plasma cleaning; the vacuum baking treatment temperature is 300°C;

[0026] Step 2: Using magnetron sputtering to bombard the titanium carbide target with argon ions, a titanium carbide film with a thickness of 100 nm is plated on the single crystal diamond sheet pretreated in step 1; the power used in the magnetron sputtering method is 400 W, and the vacuum degree used is less than 10 -5 Pa, argon gas was introduced during the process and the argon flow rate was 40 sccm;

[0027] Step 3: The single crystal diamond sheet coated with titanium carbide film in step 2 is sealed in a quartz tube, and the vacuum is evacuated to a vacuum degree of less than 10 -5 Pa and filled with hydrogen to 0.8 atmospheres, and then low-temperature annealing is performed; the low-temperature annealing temperature is 400° C. and the holding time is 15 hours;

[0028] Step 4: After the low-temperature annealing in step 3 is completed, the diamond heat sink is cooled to room temperature at an extremely low cooling rate of 0.3°C / min, and a high-quality metal carbide film is obtained on the surface.

[0029] Figure 1 The SEM morphology of the high-quality metal carbide film prepared on the surface of the diamond heat sink in this embodiment is as follows: Figure 1 It can be seen that the metal carbide film has no cracking or falling off on the surface, and has a high-quality surface.

[0030] Figure 2 The AFM morphology of the high-quality metal carbide film prepared on the surface of the diamond heat sink in this embodiment is shown in FIG. Figure 2 It can be seen that the surface roughness of the metal carbide film is extremely low, R q Less than 2nm, with high-quality surface.

[0031] Comparative Example 1

[0032] This comparative example comprises the following steps:

[0033] Step 1: Grinding, polishing, and cleaning the surface of a millimeter-sized single-crystal diamond sheet with a sheet diameter greater than 2 mm and a thickness of 1 mm, and then performing a vacuum baking treatment to obtain a pretreated single-crystal diamond sheet; the grinding process sequentially uses diamond suspensions with particle sizes of 3 μm and 0.5 μm for grinding, and the cleaning includes acetone, ethanol solution cleaning, and plasma cleaning; the vacuum baking treatment temperature is 300°C;

[0034] Step 2: Using magnetron sputtering to bombard the titanium carbide target with argon ions, a titanium carbide film with a thickness of 100 nm is plated on the single crystal diamond sheet pretreated in step 1; the power used in the magnetron sputtering method is 400 W, and the vacuum degree used is less than 10 -5 Pa, argon gas was introduced during the process and the argon flow rate was 40 sccm;

[0035] Step 3: The single crystal diamond sheet coated with titanium carbide film in step 2 is sealed in a quartz tube, and the vacuum is evacuated to a vacuum degree of less than 10 -5 Pa and filled with hydrogen to 0.8 atmospheres, and then high-temperature annealing is performed; the high-temperature annealing temperature is 800° C. and the holding time is 10 minutes;

[0036] Step 4: After the low-temperature annealing in step 3 is completed, the heat sink is cooled to room temperature at an extremely low cooling rate of 0.3°C / min, and the diamond heat sink with a metal carbide film on the surface is taken out.

[0037] Figure 3 The SEM morphology of the metal carbide film prepared on the surface of the diamond heat sink in this comparative example is as follows: Figure 3 It can be seen that the metal carbide film prepared by the traditional high temperature annealing method has cracks on the surface and the surface quality is poor.

[0038] Figure 4 The AFM morphology of the metal carbide film prepared on the surface of the diamond heat sink in this comparative example is as follows: Figure 4 It can be seen that the surface roughness of the metal carbide film prepared by the traditional high temperature annealing method is relatively high, R q If the particle size is greater than 5nm, the surface quality is poor.

[0039] Example 2

[0040] This embodiment includes the following steps:

[0041] Step 1: Grinding, polishing, and cleaning the surface of a millimeter-sized single-crystal diamond sheet with a sheet diameter greater than 2 mm and a thickness of 1 mm, and then performing a vacuum baking treatment to obtain a pretreated single-crystal diamond sheet; the grinding process sequentially uses diamond suspensions with particle sizes of 3 μm and 0.5 μm for grinding, and the cleaning includes acetone, ethanol solution cleaning, and plasma cleaning; the vacuum baking treatment temperature is 150°C;

[0042] Step 2: Using magnetron sputtering to bombard the titanium carbide target with argon ions, a titanium carbide film with a thickness of 20 nm is plated on the single crystal diamond sheet pretreated in step 1; the power used in the magnetron sputtering method is 200 W, and the vacuum degree used is less than 10 -5 Pa, argon gas was introduced during the process and the argon flow rate was 30 sccm;

[0043] Step 3: The single crystal diamond sheet coated with titanium carbide film in step 2 is sealed in a quartz tube, and the vacuum is evacuated to a vacuum degree of less than 10 -5 Pa and filled with hydrogen to 0.8 atmospheres, and then low-temperature annealing is performed; the low-temperature annealing temperature is 300° C. and the holding time is 10 hours;

[0044] Step 4: After the low-temperature annealing in step 3 is completed, the diamond heat sink is cooled to room temperature at an extremely low cooling rate of 0.1°C / min, and a high-quality metal carbide film is obtained on the surface.

[0045] Example 3

[0046] This embodiment includes the following steps:

[0047] Step 1: Grinding, polishing, and cleaning the surface of a millimeter-sized single-crystal diamond sheet with a sheet diameter greater than 2 mm and a thickness of 1 mm, and then performing a vacuum baking treatment to obtain a pretreated single-crystal diamond sheet; the grinding process sequentially uses diamond suspensions with particle sizes of 3 μm and 0.5 μm for grinding, and the cleaning includes acetone, ethanol solution cleaning, and plasma cleaning; the vacuum baking treatment temperature is 400°C;

[0048] Step 2: Using magnetron sputtering to bombard the titanium carbide target with argon ions, a titanium carbide film with a thickness of 200 nm is plated on the single crystal diamond sheet pretreated in step 1; the power used in the magnetron sputtering method is 500 W, and the vacuum degree used is less than 10 -5 Pa, argon gas was introduced during the process and the argon flow rate was 50 sccm;

[0049] Step 3: The single crystal diamond sheet coated with titanium carbide film in step 2 is sealed in a quartz tube, and the vacuum is evacuated to a vacuum degree of less than 10 -5Pa and filled with hydrogen to 0.8 atmospheres, and then low-temperature annealing is performed; the low-temperature annealing temperature is 500° C. and the holding time is 20 hours;

[0050] Step 4: After the low-temperature annealing in step 3 is completed, the diamond heat sink is cooled to room temperature at an extremely low cooling rate of 0.5°C / min, and a high-quality metal carbide film is obtained on the surface.

[0051] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a high-quality metal carbide film on a diamond heat sink, characterized in that: The method comprises the following steps: Step 1: grinding, polishing and cleaning the surface of a millimeter-sized single-crystal diamond sheet, and then performing a vacuum baking treatment to obtain a pre-treated single-crystal diamond sheet; the vacuum baking treatment temperature is 150° C. to 400° C.; Step 2: Using magnetron sputtering to bombard the titanium carbide target with argon ions, a titanium carbide film with a nanometer thickness is plated on the single crystal diamond sheet pretreated in step 1; the power used in the magnetron sputtering method is 200W to 500W, and the thickness of the titanium carbide film is 20nm to 200nm; Step 3: The single crystal diamond sheet coated with a nanometer-thick titanium carbide film in Step 2 is sealed in a quartz tube, vacuumed and filled with hydrogen during the sealing process, and then subjected to low-temperature annealing; the low-temperature annealing temperature is 300° C. to 500° C., and the holding time is 10 h to 20 h; Step 4: After the low-temperature annealing in step 3 is completed, the diamond heat sink is cooled to room temperature at an extremely low cooling rate, and a high-quality metal carbide film is obtained on the surface; the extremely low cooling rate is 0.1°C / min to 0.5°C / min.

2. The method for preparing a high-quality metal carbide film on a diamond heat sink according to claim 1, characterized in that: The grinding process in step 1 is carried out successively using diamond suspensions with particle sizes of 3 μm and 0.5 μm, and the cleaning includes acetone, ethanol solution cleaning and plasma cleaning.

3. The method for preparing a high-quality metal carbide film on a diamond heat sink according to claim 1, characterized in that: The vacuum degree used in the magnetron sputtering method in step 2 is lower than 10 -5 Pa, argon gas was introduced during the process and the argon flow rate was 30 sccm to 50 sccm.

4. The method for preparing a high-quality metal carbide film on a diamond heat sink according to claim 1, wherein: The vacuum is drawn to a degree of less than 10 -5 Pa, the hydrogen is filled to 0.8 atmospheres.

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