Microwave plasma CVD cavity structure and MPCVD equipment

Abstract

The invention relates to the technical field of vacuum microelectronics, and discloses a microwave plasma CVD cavity structure and MPCVD equipment, the CVD cavity structure comprises a copper table body and a substrate bearing surface arranged at the top of the copper table body, a copper column is arranged above the copper table body, a sunken part is arranged on one side, opposite to the copper table body, of the copper column, and the substrate bearing surface is arranged on the other side of the copper column. The substrate bearing surface is semi-surrounded by the sunken part, a gap delta H is reserved between the sunken part and the substrate bearing surface, and delta H is larger than or equal to 5mm and smaller than or equal to 50mm; the included angle theta between the axial center line of the copper column and the center axis of the copper table body is larger than or equal to 0 degree and smaller than or equal to 60 degrees. The invention aims to effectively enhance the intensity of the electric field above the substrate and greatly improve the distribution uniformity of the electric field on the premise of not obviously increasing the manufacturing cost and the process complexity, thereby providing a reliable solution for realizing large-area, high-uniformity and high-stability plasmas.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vacuum microelectronic technology, in particular to a microwave plasma CVD cavity structure and an MPCVD device. BACKGROUND

[0002] Microwave plasma chemical vapor deposition (MPCVD) technology is a key equipment for preparing high-quality diamond, gallium nitride and other semiconductor materials. Its principle is to use microwave energy to excite process gas (such as CH4 / H2) in the reaction chamber to generate high-density, high-activity plasma, so that the material is uniformly and rapidly deposited on the substrate surface.

[0003] In a typical MPCVD device, the substrate support (usually made of a good conductor such as copper, also known as "copper platform") is a core component. It not only can fix and heat the substrate, but also its geometry and structure directly affect the electromagnetic field distribution, plasma shape and material deposition quality in the reaction chamber.

[0004] At present, the substrate of mainstream MPCVD equipment is mostly in cylindrical or platform shape structure, but this traditional flat-top design has many defects. First, the electric field intensity is insufficient and the gas distribution is uneven. After the microwave is transmitted into the chamber, the electric field distribution above the copper platform is easy to concentrate or decay in the edge area, resulting in significant difference in electric field intensity between the center and the edge. Electric field is the direct power to excite and maintain plasma, and insufficient intensity will limit the overall volume and density of plasma, and uneven distribution will make the plasma spherical shape unstable, the growth sample state poor, and difficult to expand. Second, the plasma area is limited and the uniformity is poor. Due to the uneven electric field distribution, the excited plasma is concentrated in the center area of the substrate, and it is difficult to expand to the edge and larger area, and there is a gradient in the plasma density in the radial direction of the substrate, resulting in uneven material deposition rate and properties, especially when preparing large-size diamond film or epitaxial wafer, which affects the product yield and performance consistency. Third, the process window is narrow. In order to obtain a larger area of plasma, the operator is often forced to increase the microwave input power, which not only increases the energy consumption and equipment operation cost, but also may cause mode jump, plasma instability and even thermal damage to the substrate material due to excessive power, thereby narrowing the stable and efficient process window. SUMMARY

[0005] To solve the existing problems, the present application provides a microwave plasma CVD cavity structure, which aims to effectively enhance the electric field intensity above the substrate and significantly improve the uniformity of its distribution without significantly increasing the manufacturing cost and process complexity, thereby providing a reliable solution for realizing large-area, high-uniformity and high-stability plasma.

[0006] In order to achieve the above purpose, the present application provides the following technical solutions.

[0007] The application provides a microwave plasma CVD cavity structure, which comprises a copper platform body and a substrate bearing surface arranged on the top of the copper platform body, a copper column is arranged above the copper platform body, a recess is arranged on one side of the copper column relative to the copper platform body, the recess semi-surrounds the substrate bearing surface, a gap ΔH is left between the recess and the substrate bearing surface, and 5mm≤ΔH≤50mm; and an included angle θ between an axial center line of the copper column and a central axis of the copper platform body satisfies 0°≤θ≤60°.

[0008] As a further improvement of the application, the side of the copper column relative to the copper platform body is a smooth curved surface.

[0009] As a further improvement of the application, the surface of the copper column opposite to the projection area of the copper platform body is a plane, and the remaining surface of the copper platform body is a smooth curved surface.

[0010] As a further improvement of the application, the recess on the side of the copper column relative to the copper platform body is a smooth curved surface.

[0011] As a further improvement of the application, the height H1 of the copper column and the thickness H2 of the copper platform body satisfy 0.5≤H1 / H2≤3.

[0012] As a further improvement of the application, the cross section of the copper column is circular, polygonal or irregular, and the diameter or maximum width D satisfies 10mm≤D≤100mm.

[0013] As a further improvement of the application, the copper column and the copper platform body are integrally formed in a reaction chamber or detachably connected in the reaction chamber.

[0014] As a further improvement of the application, the bottom of the recess is provided with the same structure as the substrate bearing surface.

[0015] The application further discloses an MPCVD device, which comprises a reaction chamber, a microwave generator and a base, and the base adopts the microwave plasma CVD cavity structure according to any one of claims 1-8.

[0016] As a further improvement of the application, a waveguide is arranged between the reaction chamber and the microwave generator, and a three-pin adjuster is arranged in the waveguide.

[0017] Compared with the prior art, the application has the following beneficial effects: The CVD cavity structure sets a copper column with a specific recess above the copper table body, and specifies the gap range between the recess and the substrate bearing surface and the angle range between the axial center line of the copper column and the central axis of the copper table body. This structure optimizes the distribution and effect of microwave plasma in the CVD cavity, helps to improve the quality and uniformity of the deposited film, and reasonable gap and angle settings may reduce energy loss and improve energy utilization efficiency.

[0018] Preferably, the side of the copper column relative to the copper table body is a smooth curved surface, which can reduce scattering and reflection loss of microwave plasma during propagation, make the plasma more stable and uniform to act on the substrate on the substrate bearing surface, and further improve the quality and consistency of film deposition.

[0019] Preferably, the surface of the copper column opposite to the projection area of the copper table body is a plane, and the rest of the surface is a smooth curved surface. This structure further controls the propagation and action of microwave plasma in a specific area. The plane area is conducive to concentrating energy for film deposition, and the smooth curved surface can reduce unnecessary energy reflection and interference, improving deposition effect and equipment performance.

[0020] Preferably, the recess is a smooth curved surface. This structure can meet the requirements of different processes and optimize the flow and distribution of microwave plasma between the recess and the substrate bearing surface, forming a more favorable plasma environment for film deposition.

[0021] Preferably, the ratio range of the height of the copper column to the thickness of the copper table body is limited, which can coordinate the spatial layout and structural relationship of the two in the cavity, make the propagation path and action area of microwave plasma in the cavity more reasonable, and help to improve the overall performance of the equipment and the quality of film deposition. At the same time, this ratio range also considers the stability of the equipment and the feasibility of the manufacturing process.

[0022] Preferably, different cross-sectional shapes and sizes provide options for the process, which will affect the propagation and distribution of microwave plasma.

[0023] Preferably, the copper column and the copper table body can be integrally formed in the reaction chamber or detachably connected. Integrally formed can help to improve the structural stability and overall performance of the equipment, reduce energy loss and potential failure points at the connection site; detachable connection facilitates the maintenance, repair and component replacement of the equipment, improves the maintainability and service life of the equipment, and reduces the use cost.

[0024] Preferably, the bottom of the recess is provided with the same structure as the substrate bearing surface, which can make the action of microwave plasma between the recess and the substrate bearing surface more consistent and uniform, provide a more stable deposition environment for the substrate, and help to improve the quality and performance of film deposition, especially in large-area or multi-area deposition to ensure the consistency of deposition effect in each area.

[0025] The MPCVD device adopts the microwave plasma CVD cavity structure of any one of claims 1-8 as a base, improves the performance of the entire MPCVD device, such as improving the film deposition quality, uniformity, optimizing the energy utilization efficiency, etc., so that the device has better application effect and competitiveness in the field of material preparation, etc.

[0026] Preferably, a three-pin regulator is arranged in the waveguide between the reaction chamber and the microwave generator. The three-pin regulator can isolate the influence of the environment in the reaction chamber (such as impurities, gas backflow, etc. that may be generated) on the microwave generator without affecting the transmission of microwaves, protect the microwave generator, improve the stability and reliability of the device, prolong the service life of the device, and at the same time ensure that microwaves can be stably and efficiently transmitted to the reaction chamber for film deposition. BRIEF DESCRIPTION OF DRAWINGS

[0027] The drawings described herein are for illustrative purposes only and do not limit the scope of the present disclosure in any way. In addition, the shapes and scale of the components in the drawings are only illustrative and are used to help understand the present application, and are not specific limitations on the shapes and scale of the components. In the drawings: Figure 1 is a cross-sectional view of an existing microwave plasma CVD cavity structure; Figure 2 is a cross-sectional view of a microwave plasma CVD cavity structure in Example 1; Figure 3 is a cross-sectional view of an MPCVD device structure in Example 1.

[0028] Wherein, 1, copper platform body; 2, substrate bearing surface; 3, copper column; 4, recess; 5, reaction chamber; 6, microwave generator; 7, waveguide; 8, three-pin regulator. DETAILED DESCRIPTION

[0029] In order for those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0030] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] like Figure 1 As shown, in the existing microwave plasma CVD cavity structure, a substrate support surface 2 for placing a substrate is provided at the top center of the copper stage body 1.

[0033] Example 1 This embodiment provides a novel microwave plasma CVD cavity structure.

[0034] The base consists of a copper platform body 1 made of high-purity oxygen-free copper. The copper platform body 1 is cylindrical with a diameter of 200 mm and a height H2 of 30 mm. A substrate support surface 2 for placing a substrate (such as a silicon wafer or diamond wafer) is provided at the center of the top of the copper platform body 1.

[0035] The core improvement of this invention lies in the fact that an integrally formed cylindrical copper pillar 3 is machined on the upper surface of the copper platform body 1, above the substrate bearing surface 2. The angle θ between the axial center line of the copper pillar 3 and the central axis of the copper platform body 1 is 0° (i.e., vertically upward).

[0036] The copper pillar 3 has a diameter D of 80 mm and a height H1 of 80 mm. The top of the copper pillar 3 is machined into a hemispherical dome structure to reduce the electric field concentration effect and prevent excessive discharge.

[0037] Tests and Results: The base of this embodiment was installed in an MPCVD device, and a comparative experiment was conducted with the control example (traditional flat-top copper stage) under the same process conditions (chamber pressure 90 Torr, hydrogen flow rate 500 sccm, microwave power 3kW): Electric field simulation: Simulation results from the electromagnetic simulation software (COMSOL) show that the average electric field strength above the substrate plane is increased by approximately 40%. The uniformity of the reactant gas is improved by 30%.

[0038] Deposition effect: After diamond film deposition, the deposition rate was measured to be increased by about 25%, and the film thickness uniformity (within the wafer) was significantly improved.

[0039] Example 2 This embodiment provides another detachable design.

[0040] The copper column body 1 structure is similar to that of Example 1. The difference is that the copper column 3 is a separate component. There are mounting holes with internal threads embedded on the upper surface of the cavity body, and the bottom of the copper column 3 is processed with matching external threads, and the detachable connection is achieved by screwing.

[0041] The cross section of the copper column 3 is square, and the maximum width D is 40 mm. The top of the copper column 3 is a four-pyramidal pointed structure. The height H1 of the copper column 3 is 120 mm, and the height H2 of the copper column body 1 is 40 mm. The angle θ between the axial center line of the copper column 3 and the central axis of the copper column body 1 is 0°.

[0042] Beneficial effect: This detachable design allows quick replacement of copper columns 3 of different heights, top shapes or materials according to different process requirements (such as using different gas chemistry or target deposition area), providing high process flexibility and scalability.

[0043] Example 3 This embodiment is similar in structure to Example 1, and the main difference is the selection of parameters.

[0044] The angle θ between the axial center line of the copper column 3 and the central axis of the copper column body 1 is 30°.

[0045] The height H1 of the copper column 3 is 50 mm, and the height H2 of the copper column body 1 is 50 mm. The top of the copper column 3 is a multi-stage ladder structure.

[0046] This parameter combination can more effectively suppress unstable modes and preferentially excite the required main mode under certain microwave modes (such as when there is mode competition), thereby expanding the plasma area while further enhancing the stability of the plasma.

[0047] Example 4 This embodiment provides a microwave plasma CVD cavity structure, wherein a copper column 3 is arranged above the copper column body 1, the copper column 3 is provided with a recess 4 on one side relative to the copper column body 1, the recess 4 forms a half-enclosure to the substrate bearing surface 2, and a gap ΔH is left between the recess 4 and the substrate bearing surface 2, and 5 mm≤ΔH≤50 mm; the angle θ between the axial center line of the copper column 3 and the central axis of the copper column body 1 satisfies 0°≤θ≤60°.

[0048] AsFigure 2 As shown, the copper pillar 3 has a smooth curved surface on one side relative to the copper platform body 1.

[0049] Preferably, the surface of the copper column 3 in the projection area of ​​the copper platform body 1 facing the copper column 3 is a plane, and the remaining surfaces of the copper platform body 1 are smooth curved surfaces.

[0050] Optionally, the recessed portion 4 on one side of the copper pillar 3 relative to the copper platform body 1 is a smooth curved surface.

[0051] Preferably, the height H1 of the copper column 3 and the thickness H2 of the copper platform body 1 satisfy: 0.5≤H1 / H2≤3.

[0052] Optionally, the cross-section of the copper pillar 3 is circular, polygonal, or irregular, and its diameter or maximum width D satisfies: 10mm≤D≤100mm.

[0053] Preferably, the bottom of the recessed portion 4 has the same structure as the substrate bearing surface 2. Optionally, in the CVD chamber structure of this embodiment, the copper pillar 3 and the copper stage body 1 are integrally formed in the reaction chamber 5 or detachably connected to the reaction chamber 5.

[0054] Example 5 The difference between this embodiment and Embodiment 1 is that: 1) This embodiment also discloses an MPCVD device, including a reaction chamber 5, a microwave generator 6 and a base, wherein the base adopts the microwave plasma CVD cavity structure of any one of claims 1-8.

[0055] 2) It also includes a waveguide 7 between the reaction chamber 5 and the microwave generator 6, and a three-pin adjuster 8 is provided in the waveguide 7.

[0056] like Figure 3 As shown, an MPCVD apparatus includes a reaction chamber 5, a microwave generator 6, and a base. The base extends into the reaction chamber 5, and a copper stage body 1 is mounted on the base. A substrate support surface 2 is provided on the top of the copper stage body 1. A copper pillar 3 extends downward from the inner top wall of the reaction chamber 5, and the bottom of the copper pillar 3 has a recess 4. The microwave generator 6 is laterally connected to a cavity surrounding the base via a horizontally placed waveguide 7, which is connected to the reaction chamber 5. A three-pin adjuster 8 is provided inside the waveguide 7.

[0057] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A microwave plasma CVD cavity structure, comprising a copper stage body (1) and a substrate support surface (2) disposed on its top, characterized in that: A copper column (3) is provided above the copper platform body (1). A recess (4) is provided on one side of the copper column (3) relative to the copper platform body (1). The recess (4) forms a semi-encirclement of the substrate bearing surface (2). A gap ΔH is left between the recess (4) and the substrate bearing surface (2), and 5mm≤ΔH≤50mm. The angle θ between the axial center line of the copper column (3) and the central axis of the copper platform body (1) satisfies 0°≤θ≤60°.

2. The microwave plasma CVD cavity structure according to claim 1, characterized in that, The copper pillar (3) has a smooth curved surface on one side relative to the copper platform body (1).

3. The microwave plasma CVD cavity structure according to claim 2, characterized in that, The surface of the copper column (3) in the projection area of ​​the copper platform body (1) facing the copper column (3) is a plane, and the rest of the surfaces of the copper platform body (1) are smooth curved surfaces.

4. The microwave plasma CVD cavity structure according to claim 1, characterized in that, The recess (4) on one side of the copper pillar (3) relative to the copper platform body (1) is a smooth curved surface.

5. The microwave plasma CVD cavity structure according to claim 1, characterized in that, The height H1 of the copper column (3) and the thickness H2 of the copper platform body (1) satisfy: 0.5≤H1 / H2≤3.

6. The microwave plasma CVD cavity structure according to claim 1, characterized in that, The cross-section of the copper column (3) is circular, polygonal or irregular, and its diameter or maximum width D satisfies: 10mm≤D≤100mm.

7. The microwave plasma CVD cavity structure according to claim 1, characterized in that, It also includes a reaction chamber (5), wherein the copper column (3) and the copper platform body (1) are integrally formed in the reaction chamber (5) or detachably connected to the reaction chamber (5).

8. The microwave plasma CVD cavity structure according to claim 1, characterized in that, The bottom of the recess (4) has the same structure as the substrate bearing surface (2).

9. An MPCVD apparatus, comprising a reaction chamber (5), a microwave generator (6), and a base, characterized in that: The base adopts the microwave plasma CVD cavity structure as described in any one of claims 1-8.

10. An MPCVD apparatus according to claim 9, characterized in that, It also includes a waveguide (7) between the reaction chamber (5) and the microwave generator (6), and a three-pin adjuster (8) is provided in the waveguide (7).

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