Method for growing high-quality heteroepitaxial monocrystal diamond in stages
Through phased growth method and BEN treatment technology, combined with the special-shaped molybdenum retentate, the problem of high dislocation density in the growth of heteroepitaxial diamond was solved, and high-quality heteroepitaxial diamond single crystals were successfully grown.
Patent Information
- Application Number
- CN202510364442.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-26
- Publication Date
- 2025-06-20
AI Technical Summary
During the growth of heteroepitaxial diamonds, the dislocation density is high, making it difficult to obtain high-quality single crystal diamonds.
Using a staged growth method, the Ir/MgO or Ir/Sapphire composite substrate was BEN treatment in the MPCVD device to obtain a high-density and high-oriented diamond core. Then, through two stages of growth, each stage adopts a different growth atmosphere and a special-shaped molybdenum (Mo) retention to grow high-quality heteroepitaxial diamond single crystals with a thickness of more than 300 microns.
The growth of high-quality heteroepitaxial diamond single crystals is achieved, the dislocation density is reduced, and the crystal quality of single crystal diamond is improved.
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Figure CN120174480A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of crystal growth of semiconductor materials, and relates to a technical solution for growing high-quality heteroepitaxial diamond single crystals by using a special molybdenum (Mo) holder in two stages and with different shapes. Background Art
[0002] Diamond is known as the "ultimate semiconductor" material and shows great application potential in directions such as thermal management, power devices, extreme condition detectors, and quantum computing, and has a huge promoting effect on the development of key fields such as aerospace instruments, new-generation communication technology base stations, and ultra-high-speed computing. The preparation of large-size and high-quality wafers is a prerequisite for the wide commercial application of diamond, and heteroepitaxial technology has significant advantages in growing large-size wafers. The diamond heteroepitaxial growth single-crystal diamond technology usually selects an iridium (Ir) composite substrate. Limited by cost, a single-crystal Ir thin film is generally prepared on an oxide single-crystal substrate such as magnesium oxide (MgO) or sapphire. Subsequently, the bias-enhanced nucleation (BEN) technology is used to apply a bias electric field to the reaction gas in a chemical vapor deposition chamber such as a direct current plasma (DCCVD) or microwave plasma (MPCVD). The charged particles in the gas are accelerated by the electric field to obtain kinetic energy, bombard the substrate directionally, and promote diamond nucleation. Finally, after the BEN treatment is completed, the highly oriented diamond grains grow through high-quality texture and fuse with each other to form a single-crystal diamond film.
[0003] Heteroepitaxial diamond growth, as a promising method for expanding the size of single-crystal diamond, has received attention from researchers in recent years. However, heteroepitaxial technology also has a significant drawback, that is, compared with homoepitaxial growth, the dislocation density of heteroepitaxial growth is higher, making it difficult to obtain high-quality single-crystal diamond.
[0004] Therefore, for how to solve the problem of the crystal quality of heteroepitaxial diamond, the research on substrate preparation technology, BEN treatment technology, and high-quality growth technology is essential. Summary of the Invention
[0005] Regarding the high-quality growth technology in the above problems, the present invention provides a method for growing high-quality heteroepitaxial single-crystal diamond in stages. In this method, high-density and highly oriented diamond nuclei are obtained by performing BEN treatment on Ir / MgO and Ir / Sapphire composite substrates in an MPCVD device, and then through two-stage growth, different growth atmospheres and special-shaped molybdenum (Mo) holders are used in each stage to grow high-quality heteroepitaxial diamond single crystals with a thickness of more than 300 microns. The technical solution adopted by the present invention is specifically as follows: A method for growing high-quality heteroepitaxial single-crystal diamond in stages, the specific steps are as follows: 1) Place the substrate on the surface of the Mo carrier and transfer it to a microwave plasma chemical vapor deposition (MPCVD) device for bias-enhanced nucleation (BEN) treatment to obtain diamond nuclei with high density and high orientation; 2) After the BEN treatment is completed, perform the first-stage growth (in-situ growth stage). Under the conditions of a balanced gas pressure of 40-60 torr, a methane volume percentage concentration of 4-6%, and a temperature of 850-950 °C, stop introducing methane after growing for 3-5 minutes and maintain for 10-15 minutes, then perform hydrogen annealing, and take it out after cooling; 3) After taking out the substrate, place it in a frustum-shaped closed Mo carrier. The frustum-shaped closed Mo carrier consists of a disc-shaped base and a frustum in the center of the base. There is a groove for placing the substrate in the center of the frustum. The substrate undergoes the second-stage growth (secondary growth stage) in the groove. Under the conditions of a balanced gas pressure of 70-90 torr, a methane volume percentage concentration of 4-6%, and a temperature of 850-950 °C, grow for more than 48 hours to obtain a heteroepitaxial single-crystal diamond film.
[0006] Preferably, in step 1), the substrate is an Ir / MgO or Ir / Sapphire composite substrate.
[0007] Preferably, the Ir / MgO and Ir / Sapphire composite substrates are composite substrates with an orientation relationship of Ir(100) / MgO(100) and Ir(100) / Sapphire(11-20) prepared on a MgO or Sapphire single-crystal substrate through a magnetron sputtering device.
[0008] Preferably, in step 1), the BEN treatment is to isolate the sample stage in the cavity from the cavity wall, make the sample stage receive a negative voltage and the cavity wall be grounded to form a directional electric field, so that the charged substances in the plasma excited by the microwave bombard the Ir composite substrate; the parameters set for the bias-enhanced nucleation treatment are a balanced gas pressure of 26-28 torr, a methane volume percentage concentration of 4-8%, a temperature of 680-720 °C, and a bias voltage of -300 to -320 V, and the treatment time is 40 minutes.
[0009] Preferably, the conditions for the first-stage growth in step 2) are: a balanced gas pressure of 50 torr, a methane volume percentage concentration of 5%, and a temperature of 900 °C.
[0010] Preferably, the conditions for the second-stage growth in step 3) are: a balanced gas pressure of 80 torr, a methane volume percentage concentration of 5%, and a temperature of 900 °C.
[0011] Preferably, the Mo carrier described in step 1) is a disc-shaped Mo carrier, and the disc-shaped Mo carrier is provided with a circular groove for restricting heat conduction.
[0012] Advantages of the present invention: 1. The present invention realizes the coarsening and fusion of diamond grains by performing BEN treatment in an MPCVD device and carrying out the first-stage growth (in-situ growth stage), avoiding the pollution caused by taking out after nucleation.
[0013] 2. In the second-stage growth (secondary growth stage) of the present invention, a frustum-shaped closed Mo carrier is used. The frustum part can attract glow and increase the plasma energy density on the sample surface, accelerating the growth rate of diamond single crystals. At the same time, the diamond single crystals are lower than the edge of the groove, limiting the substrate and forming a closed growth environment, reducing the edge growth during the growth of diamond single crystals. Through the combination of the two, the single crystal growth rate and growth quality can be effectively improved.
[0014] 3. The present invention prepares a heteroepitaxial single-crystal diamond film with a thickness greater than 300 microns through two-stage growth, and the full width at half maximum of the diamond (004) peak of the single-crystal XRD rocking curve is 0.3°. Description of the drawings
[0015] Figure 1 Two types of Mo carriers used in Examples 1 and 2. The left figure is the disc-shaped Mo carrier used for BEN treatment and the first-stage growth (in-situ growth), and the right figure is the frustum-shaped closed Mo carrier used for the second-stage growth (secondary growth).
[0016] Figure 2 The orientation relationships of the (left figure) Ir / MgO composite substrate and the (right figure) Ir / Sapphire composite substrate used in Examples 1 and 2, respectively.
[0017] Figure 3 The results of in-situ growth for 5 min after BEN treatment on the (left figure) Ir / MgO composite substrate and the (right figure) Ir / Sapphire composite substrate, respectively.
[0018] Figure 4 The (left figure) 300-micron-thick self-supporting diamond single-crystal sample obtained after two-stage growth for 48 h on the Ir / MgO composite substrate, its (middle figure) Raman spectrum, and its (right figure) XRD rocking curve.
[0019] Figure 5 The (left figure) 330-micron-thick self-supporting diamond single-crystal sample obtained after two-stage growth for 48 h on the Ir / Sapphire composite substrate, its (middle figure) Raman spectrum, and its (right figure) XRD rocking curve. Specific Embodiments
[0020] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be noted that the following embodiments are intended to facilitate the understanding of the present application and do not impose any limitations on it.
[0021] Example 1: BEN treatment is performed on an Ir / MgO composite substrate using an MPCVD device to achieve high-density nucleation, and a self-supporting single-crystal diamond film is obtained through two-stage growth.
[0022] The commercially available single-crystal MgO is subjected to acid boiling, ethanol cleaning, acetone cleaning, and deionized water cleaning, and then placed in a magnetron sputtering device. Sputtering coating is carried out at 900 °C with a balanced gas pressure of 0.4 Pa and a sputtering power of 100 W for 30 min (average sputtering rate of 15 nm / min). After finally cooling down and taking out, a composite substrate with an orientation relationship of Ir(100) / MgO(100) is obtained.
[0023] The Ir / MgO composite substrate is cleaned with ethanol and deionized water, and then placed at the center position on the surface of a disc-shaped Mo holder and transferred to an MPCVD device; among them, the disc-shaped Mo holder is provided with a circular groove to limit heat conduction. Treatment is carried out for 40 min under the conditions of a balanced gas pressure of 27 torr, a methane volume percentage concentration of 7%, a sample temperature of 680 °C, and a bias voltage of -320 V to obtain high-density and highly oriented diamond nuclei.
[0024] After BEN is completed, the first-stage growth (in-situ growth) is carried out. Growth is carried out for 5 min at a balanced gas pressure of 50 torr, a methane volume percentage concentration of 5%, and a sample temperature of 900 °C to achieve coarsening and fusion of diamond grains, and then methane supply is stopped and maintained for 10 min, followed by hydrogen annealing. After cooling down, it is taken out; After the sample is cooled down and taken out, it is placed in a frustum-shaped closed Mo holder, and the second-stage growth (secondary growth) is carried out. Growth is carried out for 48 h at a balanced gas pressure of 80 torr, a methane volume percentage concentration of 5%, and a sample temperature of 900 °C to obtain a heteroepitaxial single-crystal diamond film with a thickness of 300 microns (average growth rate of 6.25 microns per hour).
[0025] Example 2: BEN treatment is performed on an Ir / Sapphire composite substrate using an MPCVD device to achieve high-density nucleation, and a self-supporting single-crystal diamond film is obtained through two-stage growth.
[0026] The commercially available Sapphire single crystal is put into a magnetron sputtering device after being boiled in acid, cleaned with ethanol, acetone, and deionized water. At 550 °C, the equilibrium pressure is 0.4 Pa, the sputtering power is 10 W, and sputtering coating is carried out for 60 min. Then, at the equilibrium pressure of 0.4 Pa and the sputtering power of 100 W, sputtering coating is carried out for 50 min. Subsequently, the Ir / Sapphire composite substrate is annealed at 1050 °C for 4 h. After cooling and taking out, a composite substrate with an orientation relationship of Ir(100) / Sapphire(11-20) is obtained.
[0027] The Ir / Sapphire composite substrate is placed at the center of the surface of a disc-shaped Mo holder after being cleaned with ethanol and deionized water and then transferred to an MPCVD device. Under the conditions of an equilibrium pressure of 27 torr, a methane volume percentage concentration of 7%, a sample temperature of 700 °C, and a bias voltage of -300 V, it is processed for 40 min to obtain high-density and highly oriented diamond nuclei.
[0028] After BEN, the first-stage growth (in-situ growth) is carried out. At an equilibrium pressure of 50 torr, a methane volume percentage concentration of 5%, and a sample temperature of 900 °C, growth is carried out for 5 min to achieve coarsening and fusion of diamond grains. Then, the methane supply is stopped and kept for 10 min, followed by hydrogen annealing. After cooling, it is taken out; After the sample is cooled and taken out, it is put into a frustum-shaped closed Mo holder, and the second-stage growth (secondary growth) is carried out. At an equilibrium pressure of 80 torr, a methane volume percentage concentration of 5%, and a sample temperature of 900 °C, growth is carried out for 48 h to obtain a heteroepitaxial single-crystal diamond film with a thickness of 330 microns (the average growth rate is 6.8 microns per hour).
[0029] 1) Characterize the orientation relationship of the Ir / MgO and Ir / Sapphire composite substrates Figure 2 : Use an XRD device to characterize the orientation relationship of the composite substrate. The left figure shows the characterization result of the Ir / MgO composite substrate. The sharp peak between 40° and 45° is the MgO(002) diffraction peak, and the sharp peak between 45° and 50° is the Ir(002) diffraction peak. There are no miscellaneous peaks between 30° and 50°, indicating that its crystallization orientation is single and the out-of-plane orientation relationship is Ir(100) / MgO(100). The right figure shows the characterization result of the Ir / Sapphire composite substrate. The sharp peak between 35° and 40° is the Sapphire(11-20) diffraction peak, the sharp peak between 45° and 50° is the Ir(002) diffraction peak, and the peak with weaker intensity between 40° and 45° is the Ir(111) diffraction peak. There are no miscellaneous peaks between 30° and 50°, indicating that a highly oriented Ir / Sapphire composite substrate is formed.
[0030] 2) Characterize the one-stage growth results after BEN treatment on the composite substrate Figure 3 : Use SEM equipment to characterize the BEN treatment results on the composite substrate. The left figure shows the results after 5 minutes of textured growth on the Ir / MgO composite substrate. The diamond nuclei have coalesced into a film with a low surface roughness. The right figure shows the results after 5 minutes of textured growth on the Ir / Sapphire composite substrate. The diamond nuclei have coalesced into a film with a high surface roughness.
[0031] 3) Characterize the crystal quality of the single-crystal diamond film after two-stage growth for 48 hours Figure 4 : Use XRD and Raman equipment to characterize the free-standing single-crystal diamond film. Figure 4 The free-standing single-crystal diamond film prepared on the Ir / MgO composite substrate, its Raman spectrum and XRD rocking curve are shown. The full width at half maximum of the diamond zero-phonon intrinsic peak in its Raman spectrum is 6.7 cm -1 , and the full width at half maximum of the diamond (004) peak in the XRD rocking curve is 0.32°; Figure 5 The free-standing single-crystal diamond film prepared on the Ir / Sapphire composite substrate, its Raman spectrum and XRD rocking curve are shown. The full width at half maximum of the diamond zero-phonon intrinsic peak in its Raman spectrum is 6.7 cm -1 , and the full width at half maximum of the diamond (004) peak in the XRD rocking curve is 0.3°. According to the XRD tests on the Ir / MgO composite substrate and the Ir / Sapphire composite substrate, it shows that we have obtained an epitaxial substrate with a good orientation relationship. According to the in-situ growth results observed after BEN treatment on the Ir / MgO composite substrate and the Ir / Sapphire composite substrate, it shows that we have obtained high-density and highly oriented epitaxial diamond nuclei and rapidly fused them through textured growth during the in-situ growth stage. According to the tests on the single-crystal diamond samples with a thickness greater than 300 microns obtained in the two examples, the full width at half maximum of the Raman diamond zero-phonon intrinsic peak and the full width at half maximum of the diamond (004) peak in the XRD rocking curve both indicate that through two-stage growth, a heteroepitaxial single-crystal diamond thick film with good crystal quality can be obtained.
Claims
1. A method for growing high-quality heteroepitaxial single-crystal diamond in stages, characterized in that: The specific steps of this method are as follows: 1) Placing the substrate on the Mo tray surface and transferring it to a microwave plasma chemical vapor deposition device for bias-enhanced nucleation treatment to obtain high-density, high-oriented diamond nuclei; 2) After the bias-enhanced nucleation treatment is completed, the first stage of growth is carried out. Under the conditions of equilibrium pressure of 40-60 torr, methane volume percentage concentration of 4-6%, and temperature of 850-950 °C, the methane is stopped after 3-5 min of growth and maintained for 10-15 min, hydrogen annealing is performed, and the sample is taken out after cooling down; 3) After taking out the substrate, placing it in a truncated cone type closed Mo holder, the truncated cone type closed Mo holder consists of a disc-shaped base and a truncated cone in the center of the base, and a groove for placing the substrate is provided in the center of the truncated cone; the substrate undergoes a second stage of growth in the groove, under the conditions of a balanced gas pressure of 70-90 torr, a methane volume percentage concentration of 4-6%, and a temperature of 850-950°C, and grows for more than 48 hours to obtain a heteroepitaxial single crystal diamond film.
2. The method for growing high-quality heteroepitaxial single-crystal diamond in stages according to claim 1, characterized in that: In step 1), the substrate is an Ir / MgO or Ir / Sapphire composite substrate.
3. The method for growing high-quality heteroepitaxial single-crystal diamond in stages according to claim 2, characterized in that: The Ir / MgO and Ir / Sapphire composite substrates are prepared on MgO or Sapphire single crystal substrates by magnetron sputtering equipment, and the composite substrates have an orientation relationship of Ir (100) / MgO (100) and Ir (100) / Sapphire (11-20).
4. The method for growing high-quality heteroepitaxial single-crystal diamond in stages according to claim 1, characterized in that: The bias enhanced nucleation treatment described in step 1) is to isolate the sample stage in the cavity from the cavity wall, connect the sample stage to a negative voltage, and ground the cavity wall to form a directional electric field, so that the charged substances in the plasma excited by microwaves bombard the Ir composite substrate; the parameters set for the bias enhanced nucleation treatment are a balance gas pressure of 26~28 torr, a methane volume percentage concentration of 4~8%, a temperature of 680~720℃ and a bias voltage of -300~-320 V, and a treatment time of 40 min.
5. The method for growing high-quality heteroepitaxial single-crystal diamond in stages according to claim 1, characterized in that: The conditions for the first stage growth in step 2) are: equilibrium pressure 50 torr, methane volume percentage concentration 5%, and temperature 900°C.
6. The method for growing high-quality heteroepitaxial single-crystal diamond in stages according to claim 1, characterized in that: The conditions for the second stage growth in step 3) are: equilibrium pressure 80 torr, methane volume percentage concentration 5%, and temperature 900°C.
7. The method for growing high-quality heteroepitaxial single-crystal diamond in stages according to claim 1, characterized in that: In step 1), the mold support is a disc-shaped mold support, and the disc-shaped mold support is provided with a circle of annular grooves for limiting heat conduction.