A pretreatment method for improving the uniformity of diamond nucleation on large-area silicon material

Abstract

The present application relates to a method for improving the uniformity of diamond nucleation on large-area silicon material, which comprises the following steps: immersing a silicon wafer into a protective liquid, keeping the surface of the silicon wafer horizontal, and keeping the liquid surface of the protective liquid always higher than the surface of the silicon wafer; controlling the silicon wafer to do small displacement up and down in the longitudinal direction; spraying a diamond powder suspension, and the spraying point does a vortex line motion at a specific rate on the horizontal plane; detecting whether the uniformity of diamond nucleation on the silicon wafer reaches the required demand, if not, adjusting the pitch and moving rate of the vortex line motion path, and repeating the above steps until the diamond nucleation density on the silicon wafer reaches or exceeds the required demand, if so, ending. Through accurate control, the method can efficiently form nucleation defects on the surface of a large-area single crystal silicon wafer, which are beneficial to the size distribution uniformity of diamond heterogeneous nucleation, and improves the efficiency of diamond uniform heterogeneous nucleation on large-area silicon material.

Description

Technical Field

[0001] This invention relates to the field of heteroepitaxial diamond film materials, and more specifically to a pretreatment method for improving the uniformity of diamond nucleation on large-area silicon materials. Background Technology

[0002] The excellent optical properties, thermal characteristics, and weather resistance of large-area diamond films have led to their widespread application in high-tech fields such as tokamaks, high-power lasers, and heat sinks. Among the many technologies suitable for large-area diamond film growth, the uniformity of heterogeneous diamond nucleation is crucial in determining the quality and structural uniformity of diamond growth.

[0003] Currently, the main pretreatment methods for heterogeneous diamond nucleation are mechanical polishing, ultrasonic nucleation, and bias nucleation. Mechanical polishing creates tiny scratches on the substrate surface or subsurface, which are conducive to diamond nucleation. The uniformity of this defect distribution is crucial for uniform heterogeneous diamond nucleation. However, mechanical polishing also introduces impurities during the scratch formation process, increasing the difficulty of subsequent substrate processing. Ultrasonic nucleation creates tiny pits on the substrate surface. Prolonged ultrasonic treatment can create uniformly distributed pits on the substrate surface or subsurface, providing a basic environment for uniform heterogeneous diamond nucleation. However, when the substrate material is thin or contains micro-defects, prolonged ultrasonic treatment can damage the substrate itself, even causing it to fracture, affecting subsequent growth and processing. Bias nucleation is an effective method to improve the heterogeneous nucleation rate and uniformity of diamond. By setting a reasonable bias voltage to control the configuration of plasma attached to the substrate surface, a high nucleation rate and good uniformity can be obtained on the substrate surface. However, designing and developing industrial equipment with bias voltage function is very difficult, and the process control of bias voltage is also relatively strict. In particular, in the process of preparing high-quality large-area diamond films using microwave plasma chemical vapor deposition technology, bias nucleation of substrate materials with a diameter greater than 50 mm is a great challenge not only to the equipment but also to the process.

[0004] Therefore, it is necessary to develop an effective pretreatment method for heterogeneous nucleation to improve the efficiency of uniform heterogeneous nucleation on large-area substrates and meet the requirements of large-scale industrial production. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a pretreatment method for improving the uniformity of diamond nucleation on large-area silicon materials, so as to overcome the shortcomings of the prior art.

[0006] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A pretreatment method for improving the uniformity of diamond nucleation on large-area silicon materials, comprising the following steps:

[0007] S1. Immerse the silicon wafer in the protective liquid, keeping the surface of the silicon wafer horizontal and keeping the level of the protective liquid always above the surface of the silicon wafer;

[0008] S2. Control the silicon wafer to vibrate vertically with a displacement of 0.5mm to 1.0mm.

[0009] S3. Spray diamond powder suspension at a distance of at least 0.1 mm from the surface of the protective liquid, and the spray point moves in a reciprocating vortex motion at a specific speed on the horizontal plane.

[0010] S4. Check whether the uniformity of diamond nucleation on the silicon wafer meets the requirements. If it does not meet the requirements, adjust the pitch and speed of the spiral motion path, and repeat S1 to S3 until the diamond nucleation density on the silicon wafer meets or exceeds the requirements. If it meets the requirements, then the process ends.

[0011] Based on the above technical solution, the present invention can be further improved as follows.

[0012] Furthermore, the protective liquid is an organic or inorganic liquid that will not corrode the silicon wafer.

[0013] Furthermore, the protective solution is ethanol, acetone, or deionized water.

[0014] Furthermore, the level of the protective liquid is always at least 0.2 mm above the surface of the silicon wafer.

[0015] Furthermore, the up-and-down vibrations of the silicon wafer within the range of the protective liquid surface, not exceeding the liquid level, are vibrations with a frequency range of 60kHz to 2.0MHz.

[0016] Furthermore, the pressure of the sprayed diamond powder suspension is at least 0.5 MPa.

[0017] Furthermore, the diamond powder in the diamond powder suspension consists of micron-sized or nano-sized diamond particles.

[0018] Furthermore, the liquid in the diamond powder suspension is a solution that does not corrode the silicon wafer.

[0019] Furthermore, the liquid in the diamond powder suspension is ethanol, acetone, or deionized water.

[0020] The beneficial effects of this invention are as follows:

[0021] The surface of a single-crystal silicon wafer is impacted by a high-pressure diamond powder suspension, forming pits on the surface of the single-crystal silicon wafer that are conducive to the heteroepitaxial nucleation of diamond.

[0022] By controlling the movement path of the injection points, the uniformity of the distribution of pit defects on the surface of the single-crystal silicon wafer can be regulated.

[0023] By using high-frequency vibration within a small longitudinal displacement of the single-crystal silicon wafer, the uniformity of the pit particle size distribution is further improved, and the protective liquid avoids damage to the silicon wafer itself caused by the impact of the diamond powder suspension.

[0024] By precisely controlling the formation of nucleation defects on the surface of large-area single-crystal silicon wafers, which are conducive to the uniform size distribution of diamond heterogeneous nucleation, the efficiency of uniform heterogeneous nucleation of diamond on large-area silicon materials is improved. Attached Figure Description

[0025] Figure 1 A schematic diagram of the device involved in this invention.

[0026] In the diagram, 1. silicon wafer; 2. substrate; 3. lifting support; 4. container; 5. protective liquid; 6. water inlet; 7. water outlet; 8. spray gun; 9. nozzle; 10. vortex motion path. Detailed Implementation

[0027] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0028] like Figure 1 As shown, a pretreatment method for improving the uniformity of diamond nucleation on large-area silicon materials includes the following steps:

[0029] S1: Place the silicon wafer 1 on the base 2 and fix it. Adjust the lifting bracket 3 to make the surface of the silicon wafer 1 horizontal. Set this position as the initial position of the lifting bracket 3.

[0030] S2: Inject protective liquid 5 into container 4 through injection port, and adjust the injection and discharge flow rates of liquid at inlet 6 and outlet 7 so that the liquid level is always at least 0.2 mm higher than the surface of silicon wafer 1.

[0031] S3: Make the lifting bracket 3 vibrate up and down at a certain frequency within a displacement range of 0.5mm to 1.0mm below the initial position, thereby causing the silicon wafer 1 to vibrate up and down with a displacement of 0.5-1.0mm in the longitudinal direction.

[0032] S4: The suspension containing diamond powder is ejected from the spray gun 8 at a pressure of at least 0.5 MPa;

[0033] S5: Adjust the distance between the nozzle 9 of the spray gun 8 and the surface of the protective liquid 5 to be at least 0.1 mm, and make the spray gun 8 reciprocate in a vortex motion at a specific speed on the horizontal plane.

[0034] S6: Cut off the flow of diamond suspension, stop the up-and-down vibration of silicon wafer 1, and remove silicon wafer 1 from base 2;

[0035] S7: Check whether the uniformity of diamond nucleation on silicon wafer 1 meets the requirements. If it does not meet the requirements, adjust the pitch and moving speed of the vortex motion path 10 in S5, and repeat S1 to S6 until the diamond nucleation density on silicon wafer 1 meets or exceeds the requirements. If the requirements are met, the process ends.

[0036] As a further improvement to the above technical solution, the silicon wafer 1 can be fixed on the base 2 by means of clamps, adhesives, vacuum adsorption, etc.

[0037] As a further improvement to the above technical solution, the protective liquid 5 is an organic or inorganic liquid that will not corrode the silicon wafer 1, such as ethanol, acetone, deionized water, etc.

[0038] As a further improvement to the above technical solution, the up-and-down vibration of the silicon wafer 1 within the range of the liquid surface of the protective liquid 5, which is not higher than the liquid surface, is a vibration with a frequency range of 60kHz to 2.0MHz.

[0039] As a further improvement to the above technical solution, the diamond powder in the diamond powder suspension is micron-sized or nano-sized diamond particles, and the liquid in the diamond powder suspension is a solution such as ethanol, acetone, or deionized water that does not corrode the silicon wafer 1.

[0040] As a further improvement to the above technical solution, after the spray gun 8 undergoes reciprocating vortex motion, the nozzle 9 needs to at least cover the area where nucleation needs to occur on the silicon wafer 1.

[0041] Application Example 1

[0042] The following steps were taken to perform uniform diamond heteronucleation on the surface of a 70mm diameter single-crystal silicon wafer 1:

[0043] S1: Place the 70mm diameter monocrystalline silicon wafer 1 on the base 2 and fix it. Adjust the lifting bracket 3 to make the surface of the monocrystalline silicon wafer 1 horizontal. Set this position as the initial position of the lifting bracket 3.

[0044] S2: Inject protective liquid 5 deionized water into container 4 through inlet 6. When the liquid level of deionized water is at least 0.2 mm higher than the surface of silicon wafer 1, adjust the injection and discharge flow rates of deionized water at inlet 6 and outlet 7 to 4 ml / min, so that the liquid level is always 0.2 mm to 0.5 mm higher than the surface of silicon wafer 1.

[0045] S3: Make the lifting bracket 3 vibrate up and down at a frequency of 90KHz within a displacement range of 0.5mm below the initial position, thereby causing the silicon wafer 1 to vibrate up and down with a displacement of 0.5mm in the longitudinal direction.

[0046] S4: An ethanol suspension containing single-crystal diamond powder with an average particle size of 0.5 μm is ejected from the spray gun 8 at a pressure of 0.7 MPa;

[0047] S5: Adjust the distance between the nozzle 9 of the spray gun 8 and the surface of the protective liquid 5 ethanol to 0.2mm, and make the spray gun 8 reciprocate in a vortex motion with a pitch of 2mm at a speed of 0.1mm / s on the horizontal plane.

[0048] S6: After 90 min, cut off the flow of diamond suspension, stop the up-and-down vibration of silicon wafer 1, and remove silicon wafer 1 from the base 2.

[0049] S7: Under a microscope, different regions on a 70mm diameter single-crystal silicon wafer showed pits with a diameter of approximately 0.1μm, with an average density of 10¹² pits / mm². 2 The heterogeneous nucleation uniformity meets the required standards, and the pretreatment process is completed.

[0050] Application Example 2

[0051] The following steps were taken to perform uniform diamond heteronucleation on the surface of a 150mm diameter single-crystal silicon wafer 1:

[0052] S1: Place the 150mm diameter monocrystalline silicon wafer 1 on the base 2 and fix it. Adjust the lifting bracket 3 to make the surface of the monocrystalline silicon wafer 1 horizontal. Set this position as the initial position of the lifting bracket 3.

[0053] S2: Inject protective liquid 5 deionized water into container 4 through inlet 6. When the liquid level of deionized water is at least 0.1 mm higher than the surface of silicon wafer 1, adjust the injection and discharge flow rates of deionized water at inlet 6 and outlet 7 to 4 ml / min, so that the liquid level is always 0.1 mm to 0.8 mm higher than the surface of silicon wafer 1.

[0054] S3: Make the lifting bracket 3 vibrate up and down at a frequency of 1MHz within a displacement range of 0.6mm below the initial position, thereby causing the monocrystalline silicon wafer 1 to vibrate up and down with a displacement of 0.6mm in the longitudinal direction.

[0055] S4: An ethanol suspension containing single-crystal diamond powder with an average particle size of 0.1 μm is ejected from the spray gun 8 at a pressure of 0.5 MPa;

[0056] S5: Adjust the distance between the nozzle 9 of the spray gun 8 and the surface of the protective liquid 5 ethanol by 0.2mm, and make the spray gun 8 reciprocate in a vortex motion with a pitch of 3mm at a speed of 0.3mm / s on the horizontal plane.

[0057] S6: After 60 min, cut off the flow of diamond suspension, stop the up-and-down vibration of silicon wafer 1, and remove silicon wafer 1 from the base 2.

[0058] S7: Microscopic observation revealed that the central region of a 150mm diameter single-crystal silicon wafer contained an average density of 10¹² particles / mm². 2 Pits approximately 0.1 μm in diameter are distributed within a 50 mm radius from the center of the monocrystalline silicon wafer 1, with an average density of 10⁷ pits / mm². 2 The pits, approximately 0.1 μm in diameter, did not meet the required uniformity of heterogeneous nucleation. After adjusting the pitch of the vortex path 10 in S5 to 1 mm and the moving speed to 0.1 mm / s, S1-S6 were repeated until pits with an average density of 10¹³ pits / mm were distributed throughout all areas of the 150 mm diameter single-crystal silicon wafer. 2 The pits, approximately 0.1 μm in diameter, complete the pretreatment process.

[0059] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A pretreatment method for improving the uniformity of diamond nucleation on large-area silicon materials, characterized in that, Includes the following steps: S1. Immerse the silicon wafer in the protective liquid, keeping the surface of the silicon wafer horizontal and keeping the level of the protective liquid always above the surface of the silicon wafer, with the level of the protective liquid always at least 0.2 mm above the surface of the silicon wafer; S2. Control the silicon wafer to vibrate vertically with a displacement of 0.5mm to 1.0mm. The vertical vibration of the silicon wafer within the range of the protective liquid surface is within the frequency range of 60kHz to 2.0MHz. S3. Spray diamond powder suspension at a distance of at least 0.1 mm from the surface of the protective liquid, and the spray point moves in a reciprocating vortex motion with a pitch of 2 mm or 3 mm at a speed of 0.1 mm / s or 0.3 mm / s on the horizontal plane, or moves in a reciprocating vortex motion with a pitch of 3 mm at a speed of 0.3 mm / s, and the pressure of the sprayed diamond powder suspension is at least 0.5 MPa. S4. Check whether the uniformity of diamond nucleation on the silicon wafer meets the requirements. If it does not meet the requirements, adjust the pitch and speed of the vortex motion path. Specifically, change the vortex motion with a reciprocating speed of 0.3 mm / s and a pitch of 3 mm to a reciprocating speed of 0.1 mm / s and a pitch of 1 mm. Repeat S1 to S3 until the diamond nucleation density on the silicon wafer reaches or exceeds the requirements. By controlling the motion path of the injection point, regulate the uniformity of the distribution of pit defects on the surface of the single crystal silicon wafer. If the requirements are met, the process ends.

2. The pretreatment method for improving the uniformity of diamond nucleation on large-area silicon materials according to claim 1, characterized in that: The protective liquid is an organic or inorganic liquid that will not corrode the silicon wafer.

3. The pretreatment method for improving the uniformity of diamond nucleation on large-area silicon materials according to claim 2, characterized in that: The protective solution is ethanol, acetone, or deionized water.

4. The pretreatment method for improving the uniformity of diamond nucleation on large-area silicon materials according to claim 1, characterized in that: The diamond powder in the diamond powder suspension is micron-sized or nano-sized diamond particles.

5. The pretreatment method for improving the uniformity of diamond nucleation on large-area silicon materials according to claim 1, characterized in that: The liquid in the diamond powder suspension is a solution that does not corrode the silicon wafer.

6. The pretreatment method for improving the uniformity of diamond nucleation on large-area silicon materials according to claim 5, characterized in that: The liquid in the diamond powder suspension is ethanol, acetone or deionized water.

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