A 915 MHz mpcvd apparatus for 16-inch diamond wafer deposition

Abstract

The present application provides a kind of 915 MHz MPCVD device for 16 inch diamond wafer deposition, it is related to microwave plasma chemical vapor deposition technical field.The device includes shell, cavity is equipped in shell, microwave entrance is equipped in the top of shell, coaxial antenna is installed in the cavity of shell, gas inlet is equipped on coaxial antenna, gas outlet and substrate are equipped in the bottom of shell, gas inlet, gas outlet communicate cavity;Multiple microwave dielectric windows are arranged on the inner wall of shell.The present application is changed by being provided with multiple microwave dielectric windows, microwave transmission path length and phase, makes two microwave electric field areas be connected as a whole, and excites plasma, and the plasma region formed is located on substrate.The device generates continuous diameter 16 inch TM02 microwave electric field on substrate by the design of resonant cavity structure, microwave dielectric shape and position, excites large size plasma region, realizes 16 inch diamond wafer deposition.

Description

Technical Field

[0001] This invention relates to the field of microwave plasma chemical vapor deposition technology, and more particularly to a 915 MHz MPCVD apparatus for depositing 16-inch diamond wafers. Background Technology

[0002] Diamond, due to its superior physicochemical properties, has shown great application potential in high-end semiconductor devices, optical window materials, quantum information carriers, and ultra-high thermal conductivity substrates, and is regarded as a revolutionary material for next-generation power electronic devices. Microwave plasma chemical vapor deposition (MPCVD) is a core technology for preparing high-quality diamond, and the matching degree between its microwave mode design and cavity structure directly restricts the spatial distribution characteristics of the plasma.

[0003] Currently, commercial MPCVD devices generally use 2.45 GHz microwaves. Due to plasma confinement effects and standing wave mode limitations, the effective deposition area is mostly concentrated in the 2-4 inch range. Although existing 915 MHz MPCVD devices have better plasma expansion capabilities, increasing the effective deposition area by more than 2 times compared to 2.45 GHz MPCVD devices, they still face bottlenecks in expanding the deposition area due to the limitations of traditional single electric fields, with the effective deposition area mostly concentrated in the 5-8 inch range. This is because the TM02 mode microwave electric field excited by the large cavity size of the 915 MHz MPCVD device is usually two discrete electric field regions: a central hemispherical microwave electric field and an outer ring microwave electric field, resulting in a small plasma diameter and making it impossible to deposit large-size diamond films of 16 inches. Summary of the Invention

[0004] To address the aforementioned problems, the present invention provides the following technical solution:

[0005] A 915 MHz MPCVD device for depositing 16-inch diamond wafers includes a housing with a cavity inside. A coaxial antenna is installed in the cavity of the housing, and an air inlet is provided on the coaxial antenna. An air outlet is provided at the bottom of the housing, and the air inlet and the air outlet communicate with the cavity. A substrate is provided at the bottom of the housing within the cavity, and a plasma region formed by excited plasma is located on the substrate.

[0006] The inner wall of the housing is provided with multiple microwave dielectric windows, which divide the cavity into multiple resonant cavities.

[0007] Optionally, the plurality of microwave dielectric windows may be arranged in any region within the cavity except for the plasma region formed by plasma.

[0008] Optionally, the housing includes a protrusion, a second microwave dielectric window is installed in the protrusion, a top section of a coaxial antenna is installed in the second microwave dielectric window, a third microwave dielectric window is installed between the upper surface of the middle section of the coaxial antenna and the inner wall of the housing, and a first microwave dielectric window is installed between the bottom surface of the middle section of the coaxial antenna and the inner wall of the housing.

[0009] A closed third resonant cavity is formed between the third microwave medium window, the first microwave medium window, the middle section of the coaxial antenna, and the inner wall of the housing. A second resonant cavity is formed between the bottom surface of the middle section of the coaxial antenna, the side surface of the bottom section of the coaxial antenna, and the inner wall of the housing. A first resonant cavity is formed between the bottom surface of the bottom section of the coaxial antenna and the inner wall of the housing. The first resonant cavity is connected to the second resonant cavity.

[0010] Optionally, the first resonant cavity is cylindrical, and the diameter of the first resonant cavity is 2λ±λ / 2, where λ is the microwave wavelength; the second resonant cavity is annular.

[0011] A TM02 mode microwave electric field is generated in the first resonant cavity. The microwave electric field includes a central hemispherical microwave electric field and a ring microwave electric field. The two microwave electric field regions are connected and excite plasma to form a plasma region.

[0012] Optionally, the number of microwave medium windows is greater than or equal to 3.

[0013] Optionally, the microwave dielectric window is made of a microwave-transparent material, and the microwave dielectric window is made of quartz glass, alumina, silicon nitride, boron nitride, or a composite material formed from the above materials.

[0014] Optionally, a sealing ring is installed between the microwave dielectric window and the parts connected thereto.

[0015] Optionally, the longitudinal cross-sectional shape of the microwave dielectric window is preferably rectangular, frustum-shaped, conical, or a combination of the above shapes.

[0016] Optionally, at most one of the cross-sectional shapes of the plurality of microwave dielectric windows is rectangular.

[0017] The above technical solution has at least the following advantages compared with the existing technology:

[0018] The above-described scheme, the 915 MHz MPCVD apparatus for 16-inch diamond wafer deposition of the present invention, compared with traditional MPCVD apparatuses, achieves continuous coupling of the dual electric field peaks of the TM02 mode by designing the resonant cavity structure and microwave feeding method, setting multiple microwave dielectric windows in the microwave transmission channel, and changing the microwave transmission path length and phase. The apparatus of the present invention eliminates the electric field break band in traditional multimode coupling, achieves continuous coupling of the dual electric field peaks of the TM02 mode, forms a microwave electric field region with a diameter of 16 inches or more, thereby exciting a large-area plasma region and realizing 16-inch diamond wafer deposition. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the 915 MHz MPCVD apparatus for 16-inch diamond wafer deposition according to the present invention.

[0021] Figure 2 The results of the numerical simulation of microwave electric field distribution for the 915 MHz MPCVD apparatus used for 16-inch diamond wafer deposition according to the present invention;

[0022] Figure 3 This is a comparison diagram of the continuous TM02 microwave electric field distribution of the 915 MHz MPCVD device for 16-inch diamond wafer deposition of the present invention and the microwave electric field distribution of a conventional TM02 device.

[0023] The annotations in the attached figures are explained as follows:

[0024] 1. First resonant cavity; 2. Second resonant cavity; 3. Third resonant cavity; 4. Coaxial antenna; 41. Top section of coaxial antenna; 42. Middle section of coaxial antenna; 43. Bottom section of coaxial antenna; 5. Air inlet; 6. Exhaust outlet; 7. First microwave dielectric window; 8. Second microwave dielectric window; 9. Third microwave dielectric window; 10. Microwave inlet; 11. Plasma; 12. Substrate; 13. Housing; 131. Protrusion. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising,” “including,” or “including,” and similar terms mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or “connected,” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0027] It should be noted that the terms "up", "down", "left", "right", "front", and "back" used in this invention are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0028] Example 1

[0029] like Figure 1 As shown, this embodiment provides a 915 MHz MPCVD apparatus for depositing 16-inch diamond wafers, capable of depositing 16-inch (ultra-large size) diamond wafers. It includes a housing 13 with an internal cavity. A microwave inlet 10 is located at the top of the housing 13, and a coaxial antenna 4 is mounted within the cavity. An air inlet 5 is located on the coaxial antenna 4, and an air outlet 6 is located at the bottom of the housing 13. The air inlet 5 and the air outlet 6 communicate with the cavity. Multiple microwave dielectric windows are arranged on the inner wall of the housing 13. These multiple microwave dielectric windows are arranged in any area within the cavity except for the plasma region formed by plasma 11. Specifically, the multiple microwave dielectric windows are arranged in any area within the resonant cavity except for the plasma region formed by plasma 11.

[0030] Furthermore, a substrate 12 is provided at the bottom of the inner wall of the housing 13, and plasma 11 is provided on the substrate 12.

[0031] The microwave dielectric window in this embodiment is made of a microwave-transparent material, and the microwave dielectric window is made of quartz glass, alumina, silicon nitride, boron nitride, and a composite material formed from the above materials.

[0032] Optionally, a sealing ring is installed between the microwave medium window and the parts connected thereto to enhance the sealing performance.

[0033] In this embodiment, the housing 13, the coaxial antenna 4, and the microwave dielectric window are all annular structures. The longitudinal cross-sectional shape of the microwave dielectric window is preferably rectangular, frustum-shaped, conical, or a combination of the above shapes. Specifically, the coaxial antenna 4 is coaxial with the housing 13.

[0034] Furthermore, in this embodiment, the number of microwave medium windows is greater than or equal to three, and at most one of the multiple microwave medium windows is annular.

[0035] The diameter of the plasma region formed by plasma 11 is greater than or equal to 16 inches, and the diameter of substrate 12 is greater than or equal to the diameter of plasma 11.

[0036] In this embodiment, the coaxial antenna 4 and the resonant cavity are water-cooled.

[0037] Example 2

[0038] Based on Embodiment 1, this embodiment provides a 915MHz MPCVD apparatus for 16-inch diamond wafer deposition. This apparatus has three microwave dielectric windows: a first microwave dielectric window 7, a second microwave dielectric window 8, and a third microwave dielectric window 9. The housing 13 includes a protrusion 131, within which a second microwave dielectric window 8 is installed. A top section 41 of a coaxial antenna is installed within the second microwave dielectric window 8. A third microwave dielectric window 9 is installed between the upper surface of the middle section 42 of the coaxial antenna and the inner wall of the housing 13. A first microwave dielectric window 7 is installed between the bottom section 43 of the coaxial antenna and the inner wall of the housing 13. A closed third resonant cavity 3 is formed between the third microwave dielectric window 9, the first microwave dielectric window 7, the middle section 42 of the coaxial antenna, and the inner wall of the housing 13. A second resonant cavity 2 is formed between the bottom surface of the middle section 42 of the coaxial antenna, the side surface of the bottom section 43 of the coaxial antenna, and the inner wall of the housing 13. A first resonant cavity 1 is formed between the bottom surface of the bottom section 43 of the coaxial antenna and the inner wall of the housing 13. The first resonant cavity 1 communicates with the second resonant cavity 2. The area enclosed by the first resonant cavity 1, the second resonant cavity 2, the third resonant cavity 3, and the coaxial antenna 4 constitutes a complete resonant cavity. The area enclosed by the second resonant cavity 2, the third resonant cavity 3, and the coaxial antenna 4 is the microwave transmission channel. The first resonant cavity 1 and the second resonant cavity 2 are vacuum chambers.

[0039] Furthermore, the first resonant cavity 1 is cylindrical, with a diameter of 2λ±λ / 2, where λ is the microwave wavelength. The microwave power supply frequency of this device is 915 MHz, and the diameter of the first resonant cavity 1 ranges from 492 to 820 mm, capable of depositing diamond wafers of 16 inches and above. The second resonant cavity 2 is annular cylindrical. A TM02 mode microwave electric field is generated within the first resonant cavity 1, which generates a central hemispherical microwave electric field and an annular microwave electric field. The two microwave electric field regions connect and excite plasma 11, forming a plasma region. Specifically, the diameters of the first resonant cavity 1, the second resonant cavity 2, and the third resonant cavity 3 increase sequentially.

[0040] In this embodiment, the longitudinal cross-sectional shapes of the first microwave dielectric window 7, the second microwave dielectric window 8, and the third microwave dielectric window 9 are preferably rectangular, polygonal, or combinations thereof. Specifically, the first microwave dielectric window 7, the second microwave dielectric window 8, and the third microwave dielectric window 9 are annular, the longitudinal cross-section of the first microwave dielectric window 7 is rectangular, the longitudinal cross-section of the second microwave dielectric window 8 is trapezoidal, and the longitudinal cross-section of the third microwave dielectric window 9 is hexagonal.

[0041] Specifically, a sealing ring is installed between the inner wall of the protrusion 131 and the second microwave dielectric window 8; a sealing ring is installed between the second microwave dielectric window 8 and the top section 41 of the coaxial antenna; a sealing ring is installed between the upper surface of the middle section 42 of the coaxial antenna and the third microwave dielectric window 9; a sealing ring is installed between the third microwave dielectric window 9 and the inner wall of the housing 13; a sealing ring is installed between the bottom section 43 of the coaxial antenna and the first microwave dielectric window 7; a sealing ring is installed between the inner wall of the housing 13 and the first microwave dielectric window 7; and the upper end of the first microwave dielectric window 7 is located in the microwave inlet 10 and is in contact with air.

[0042] In this embodiment, the coaxial antenna 4, the first resonant cavity 1, the second resonant cavity 2, and the third resonant cavity 3 are all water-cooled.

[0043] Example 3

[0044] Based on Embodiment 2, this embodiment provides a 915MHz MPCVD device for 16-inch diamond wafer deposition. The diameter of the first resonant cavity 1 is 520 mm, the substrate 12 is placed at the bottom of the first resonant cavity 1, and plasma 11 is excited on it. The plasma region formed by the plasma 11 has a diameter of 16 inches.

[0045] The 915 MHz MPCVD apparatus for 16-inch diamond wafer deposition of this invention is also equipped with a cooling system and a vacuum system. The cooling system and vacuum system are conventional existing technologies and will not be described in detail here. Specifically, the cooling system of this invention can employ a commonly used water cooling system, or adopt Chinese invention patents with publication (announcement) numbers CN118028972B, CN116254523B, and CN116926500B. The vacuum system of this invention can be directly activated using a vacuum pump.

[0046] The 915 MHz MPCVD apparatus for 16-inch diamond wafer deposition of this invention, compared to traditional MPCVD apparatuses, achieves continuous coupling of dual electric field peaks in TM02 mode by designing the resonant cavity structure and microwave feeding method, setting multiple microwave dielectric windows in the microwave transmission channel, and changing the microwave transmission path length and phase. Figure 2 and Figure 3 It is understood that, compared with the conventional TM02 mode of the prior art, the device of the present invention eliminates the electric field break zone in the conventional multimode coupling, realizes the continuous coupling of the dual electric field peaks of the TM02 mode, forms a microwave electric field region with a diameter of more than 16 inches, thereby exciting a large-area plasma region and realizing the deposition of 16-inch diamond wafers.

[0047] The operation of the 915 MHz MPCVD apparatus for 16-inch diamond wafer deposition according to the present invention is as follows:

[0048] A 16-inch silicon substrate 12 is placed at the bottom of the first resonant cavity 1. The power supply, cooling system, and vacuum system are turned on sequentially. After the vacuum levels of the first resonant cavity 1 and the second resonant cavity 2 reach the working requirements, H2 at 1000 sccm is introduced as the working gas. Once the cavity pressure of the vacuum cavity reaches the working cavity pressure, the 915 MHz microwave power supply is turned on, and the microwave output power is gradually adjusted to 75 kW. The external tuning device is adjusted to bring the device to the optimal deposition state. CH4 is introduced through the gas inlet 5 as a carbon source to deposit the diamond wafer. After deposition, the microwave power supply is turned off, the cavity is opened, and the diamond wafer is removed. After closing the cavity, vacuuming continues to maintain the cavity cleanliness. Then, the vacuum system, cooling system, and power supply are turned off sequentially.

[0049] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A 915 MHz MPCVD apparatus for 16 inch diamond wafer deposition, characterized in that, The device includes a housing with a cavity inside. A coaxial antenna is installed inside the cavity. The coaxial antenna has an air inlet. The bottom of the housing has an air outlet. The air inlet and the air outlet are connected to the cavity. The bottom of the housing is located inside the cavity and has a substrate. The plasma region formed by excited plasma is located on the substrate. The inner wall of the housing is provided with a plurality of microwave dielectric windows, which divide the cavity into a plurality of resonant cavities. At most one of the longitudinal cross-sectional shapes of the plurality of microwave dielectric windows is rectangular. The housing includes a protrusion, a second microwave medium window is installed in the protrusion, a top section of a coaxial antenna is installed in the second microwave medium window, a third microwave medium window is installed between the upper surface of the middle section of the coaxial antenna and the inner wall of the housing, and a first microwave medium window is installed between the bottom surface of the middle section of the coaxial antenna and the inner wall of the housing. A closed third resonant cavity is formed between the third microwave medium window, the first microwave medium window, the middle section of the coaxial antenna, and the inner wall of the housing. A second resonant cavity is formed between the bottom surface of the middle section of the coaxial antenna, the side surface of the bottom section of the coaxial antenna, and the inner wall of the housing. A first resonant cavity is formed between the bottom surface of the bottom section of the coaxial antenna and the inner wall of the housing. The first resonant cavity and the second resonant cavity are connected. A TM02 mode microwave electric field is generated in the first resonant cavity. The microwave electric field includes a central hemispherical microwave electric field and a ring microwave electric field. The two microwave electric field regions are connected and excite plasma to form a plasma region.

2. The 915 MHz MPCVD setup for 16 inch diamond wafer deposition as claimed in claim 1 wherein, The first resonant cavity is cylindrical and has a diameter of 2λ±λ / 2, where λ is the microwave wavelength. The second resonant cavity is annular.

3. The 915 MHz MPCVD setup for 16 inch diamond wafer deposition as claimed in claim 1 wherein, The microwave dielectric window is made of a microwave-transparent material, such as quartz glass, alumina, silicon nitride, or boron nitride.

4. The 915 MHz MPCVD setup for 16 inch diamond wafer deposition as claimed in claim 1 wherein, A sealing ring is installed between the microwave medium window and the parts connected thereto.

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