KR-20260067732-A - Diamond nucleation and film layer growth method

Abstract

The present invention relates to a method for diamond nucleation and film layer growth, and more specifically, provides a method for diamond nucleation and thin film layer growth characterized by comprising: a step of preparing a substrate by surface treatment; a step of loading the prepared substrate into equipment capable of generating plasma; a step of injecting a gas containing carbon into said equipment; and a step of depositing activated carbon as diamond on the substrate.

Inventors

• 정성민
• 신윤지
• 우기열

Assignees

• 한국세라믹기술원

Dates

Publication Date

20260513

Application Date

20241106

Claims (20)

1. Step of preparing a substrate by surface treating; A step of loading the prepared substrate into equipment capable of generating plasma; A step of injecting a carbon-containing gas into the above equipment; and A step of depositing activated carbon as diamond on a substrate; A method for diamond nucleation and thin film layer growth characterized by including
2. In paragraph 1, A method for diamond nucleation and thin film growth characterized in that the substrate is a non-diamond substrate.
3. In paragraph 1, A method for diamond nucleation and thin film growth, characterized in that the above-mentioned non-diamond substrate is a 4H-SiC substrate.
4. In paragraph 3, A method for diamond nucleation and thin film growth characterized by depositing on the C-face of the above 4H-SiC substrate.
5. In paragraph 1, The step of preparing the above substrate by surface treating it; First washing step with a washing solution; A step of surface treatment using diamond powder; and A second cleaning step of the surface-treated substrate; A method for diamond nucleation and thin film layer growth characterized by including
6. In paragraph 5, A method for diamond nucleation and thin film growth, characterized in that, in the first washing step above, the washing solution is washed in the order of acetone-ethanol-distilled water.
7. In paragraph 5, A method for diamond nucleation and thin film growth, characterized in that the step of surface treatment using the above diamond powder; and the step of second washing the surface-treated substrate are performed using an ultrasonic device.
8. In paragraph 5, A method for diamond nucleation and thin film layer growth, characterized in that the step of surface treatment using the above diamond powder is pre-treated for a time greater than 0 hours and less than or equal to 1 hour with an ultrasonic output of 200 to 220 W in the case of the C-face of a 4H-SiC substrate.
9. In paragraph 8, Characterized by the fact that as the time of pretreatment with the above-mentioned ultrasonic output increases within 1 hour, the diamond nucleation density increases and the grain size decreases. Diamond nucleation and thin film layer growth method.
10. In Paragraph 9, Characterized by the fact that the surface observed after the diamond film is grown is uniform when the time for pretreatment with the above ultrasonic output is within 1 hour. Diamond nucleation and thin film layer growth method.
11. In paragraph 8, A method for diamond nucleation and thin film growth, characterized in that if the time for pretreatment with the above-mentioned ultrasonic output exceeds 1 hour, curvature and scratches on the substrate surface are asymmetrically removed, resulting in a decrease in nucleation density and an increase in grain size.
12. In Paragraph 11, A method for diamond nucleation and thin film growth, characterized in that if the time for pretreatment with the above-mentioned ultrasonic output exceeds 1 hour, the nucleation density decreases, causing the diamond film to grow excessively and the surface observed after growth to be non-uniform.
13. In paragraph 8, A method for diamond nucleation and thin film growth, characterized in that the above diamond powder has a size range of 177 to 250 μm.
14. In paragraph 8, A method for diamond nucleation and thin film growth characterized by surface treatment under the above conditions such that the growth thickness of the diamond film exceeds 5㎛, the growth rate is 5㎛/h or higher, and the grain size is 3㎛ or higher.
15. In paragraph 5, In the step of surface treatment using the above diamond powder; A method for diamond nucleation and thin film growth characterized by using diamond powder mixed with ethanol to form a suspension of a predetermined concentration.
16. In paragraph 1, A method for diamond nucleation and thin film growth, characterized in that the carbon-containing gas is a mixture of methane and hydrogen.
17. In paragraph 1, A method for diamond nucleation and thin film growth characterized in that the above equipment is MPCVD (Microwave Plasma Chemical Vaper Deposition).
18. In Paragraph 17, MPCVD process conditions A method for diamond nucleation and thin film growth characterized by a methane concentration of about 6%, a pressure of about 120 Torr, a substrate temperature of about 950℃, a microwave output of about 5kW, and a growth time of 1 hour.
19. In paragraph 1, A method for diamond nucleation and thin film growth, characterized in that the above plasma is generated by radiating microwaves of 1 to 3 GHz.
20. A diamond film manufactured by the method of claim 1, characterized by having a uniform surface, a thickness of 5㎛ or more, and a grain size of 4㎛ or more.

Description

Diamond nucleation and film layer growth method The present invention relates to a method for diamond nucleation and film layer growth, wherein diamond powder is collided with a substrate on which a diamond film is grown to increase the nucleation density, and depending on the pretreatment time using diamond powder, optimal conditions for diamond nucleation growth can be established, nucleation density can be increased, and overall homogeneity of the substrate can be secured. Diamond material possesses a diamond cubic structure based on a face-centered cubic (FCC) structure through SP3 hybrid orbital bonding, in which each carbon atom forms strong σ bonds with four neighboring carbon atoms. Diamond material has physical properties including a Mohs hardness of 10, thermal conductivity of ~22 W/cm·K, breakdown electric field of >10 MV/cm, band gap of ~5.47 eV, and carrier mobilities of 4500 cm² /V·s (electron) and 3800 cm² /V·s (hole). It is also known for its very high chemical stability due to its strong covalent bonding characteristics. Therefore, diamond is utilized as a suitable material for semiconductor devices in extreme environments such as ultra-high temperatures and ultra-high voltages. Diamond growth methods include the HPHT (High Temperature High Pressure) method and the CVD method. The CVD method is further divided into the homoepitaxial growth method, which is grown on a homogeneous substrate (diamond substrate), and the heteroepitaxial growth method, which is grown on heterogeneous substrates such as sapphire, Si, and SiC. The HPHT method utilizes equipment such as HPHT Cubic Press Machines; however, this equipment is large, has a complex structure, requires high initial costs, and is characterized by a slow growth rate. On the other hand, the CVD method uses equipment such as MPCVD, HFCVD, and RFCVD; this equipment has a relatively simple structure, requires relatively low initial costs, and is characterized by a relatively fast diamond growth rate. While homoepitaxial diamond growth is difficult to achieve large diameters due to very high unit costs and size limitations of the diamond single crystal substrate, heteroepitaxial diamond growth allows for the use of various materials with relatively low unit costs as substrates, offering the advantages of cost reduction, a wider range of applications through diverse forms of heterogeneous growth, and the ability to achieve large diameters. Therefore, the applicant adopted a substrate of a different material and the CVD method to derive optimal diamond film growth conditions. Figure 1 is a diagram showing the structure of a diamond. FIG. 2 is a process diagram for forming a diamond film according to one embodiment of the present invention. Figure 3 is a drawing showing a photograph, schematic diagram, and driving method of an MPCVD equipment. FIG. 4 is a diagram showing the pretreatment process of a substrate according to one embodiment of the present invention. Figure 5 is a photograph showing a comparison of surface roughness regarding the Si-face and C-face of a 4H-SiC substrate pretreated according to one embodiment of the present invention. Figure 6 is a photograph showing the surface and cross-sectional microstructure of a diamond film grown on the C-face of a 4H-SiC substrate according to one embodiment of the invention. Figure 7 is a graph showing a comparison of the nucleation density and grain size of Si-face and C-face on a 4H-SiC substrate according to one embodiment of the present invention. The present invention will be described in more detail below based on the accompanying drawings and preferred embodiments. In the present invention, "film" refers to a "thin film" or a "thick film." FIG. 1 is a diagram showing the structure of a diamond; FIG. 2 is a process diagram for forming a diamond film according to an embodiment of the present invention; FIG. 3 is a diagram showing a photograph, schematic diagram, driving method, etc. of an MPCVD equipment; FIG. 4 is a diagram showing a pretreatment process of a substrate according to an embodiment of the present invention; FIG. 5 is a photograph showing a comparison of surface roughness regarding the Si-face and C-face of a 4H-SiC substrate pretreated according to an embodiment of the present invention; FIG. 6 is a photograph showing the surface and cross-sectional microstructure of a diamond film grown on the C-face of a 4H-SiC substrate according to an embodiment of the present invention; and FIG. 7 is a graph showing a comparison of nucleation density and grain size of the Si-face and C-face in a 4H-SiC substrate according to an embodiment of the present invention. As illustrated in FIG. 2, the diamond nucleation and thin film growth method according to the present invention comprises the steps of: preparing a substrate by surface treatment; loading the prepared substrate into equipment capable of generating plasma; injecting a gas containing carbon into the equipment; and depositing ac