Non-thermal global efficient planarization method for single crystal diamond substrate

Abstract

The invention provides a non-thermal global efficient planarization method for a single crystal diamond substrate, which comprises the following steps: S1, carrying out non-crystallization treatment on the surface of a single crystal diamond by utilizing plasma to obtain a modified single crystal diamond; and S2, carrying out chemical mechanical polishing on the modified single crystal diamond obtained in the step S1 to obtain the planarized single crystal diamond. According to the method, the pyramid-shaped rough structure can be rapidly etched and removed in the atmospheric environment, efficient planarization of the diamond substrate is achieved, and the overall process steps are simple and convenient.

Description

Technical Field

[0001] The invention belongs to the technical field of superhard and brittle material processing, and in particular relates to a non-thermal global high-efficiency flattening method for a single crystal diamond substrate. Background Art

[0002] Diamond has ultra-high hardness (100GPa), ultra-wide bandgap (5.5eV), high electron mobility (4500cm 2 / Vs), high thermal conductivity (2000W / m·K), high breakdown voltage (9.9MV / cm), low dielectric constant (5.7), strong radiation resistance and other excellent properties. It integrates excellent properties such as mechanics, electricity, heat, acoustics, optics, corrosion resistance, etc., and can meet the requirements of extreme working conditions such as ultra-high vacuum, extreme temperature, high voltage and strong radiation. Diamond can show n-type and p-type conductivity through doping. Its performance far exceeds that of other semiconductor materials and is known as the "ultimate semiconductor".

[0003] However, diamond has extremely high hardness and strong chemical inertness, which brings great challenges to the planarization process. The main manufacturing technologies currently include laser polishing, ion beam polishing, mechanical polishing, heat-assisted mechanical polishing, light-assisted mechanical polishing, chemical mechanical polishing (CMP), etc. However, high heat removal will bring about a deeper damage layer and heat diffusion layer, and mechanical polishing is difficult to achieve a low surface roughness.

[0004] Patent CN101935825A mentions the use of thermochemical mechanical polishing to flatten diamond-like carbon films, in which corundum is used as an abrasive and KMnO4 is used as an oxidant. After polishing for 60 minutes at a heating temperature of 200°C and a rotation speed of 300r / min, the surface quality can reach 1.285nm, but it uses heating and a high rotation speed, and does not mention the polishing load. Patent CN118127621A proposes a method for preparing an ultra-thin, ultra-low surface roughness self-supporting single-crystal diamond film, first by heat treatment to remove the internal stress of the epitaxial layer, and then polishing it with a cast iron disk coated with diamond powder, and the final surface roughness is 0.45nm. Patent CN113178382A proposes first grinding and thinning the wafer-level substrate, then plasma or laser etching its various partitions, and then mechanically polishing or chemically polishing the etched substrate, and the final surface quality is 0.3~0.5nm.

[0005] Therefore, there is an urgent need for a new planarization method for single crystal diamond that can ensure high-rate material removal while achieving high-precision and damage-free surface. Summary of the invention

[0006] In view of this, the present invention aims to provide a non-thermal global efficient planarization method for a single crystal diamond substrate to solve at least one technical problem in the background technology.

[0007] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0008] A non-thermal global high-efficiency planarization method for a single crystal diamond substrate comprises the following steps:

[0009] S1: using plasma to amorphize the surface of single crystal diamond to obtain modified single crystal diamond;

[0010] S2: performing chemical mechanical polishing on the modified single crystal diamond obtained in step S1 to obtain a planarized single crystal diamond.

[0011] Furthermore, the amorphization treatment in step S1 includes placing a clean and dry diamond sheet on a three-dimensional moving platform, exciting a gas with a high-frequency current to form a plasma, and performing an amorphization treatment on the surface of the single-crystal diamond with the plasma.

[0012] Further, the plasma in step S1 is formed by an atmospheric direct injection plasma machine;

[0013] And / or, the nozzle trajectory of the atmospheric direct injection plasma machine in step S1 is a rectangular trajectory;

[0014] And / or, the rectangular track in step S1 has a width of 0-100 mm, a length of 0-100 mm, a step distance of 0-100 mm, and a speed of 0.1-100 mm / s.

[0015] Furthermore, the processing time of the amorphization treatment in step S1 is 0.1 to 10000 min, and preferably, the processing time is 10 to 60 min.

[0016] Further, in step S1, the power of the plasma is 300-1200W, the gas pressure of the plasma is 0.02-1MPa, the processing distance is 0.1-50mm, and the processing pressure is 0.1-102kpa;

[0017] And / or, the working gas of the plasma includes one or more of oxygen, nitrogen, air, helium, and argon.

[0018] Furthermore, the load of the chemical mechanical polishing in step S2 is 0.01-10 kg / cm 2 , the speed is 0.1~1200r / min, and the time is 0.1~1000h.

[0019] Furthermore, the polishing liquid of the chemical mechanical polishing in step S2 includes a polishing solvent, polishing abrasive particles and an oxidant.

[0020] Furthermore, the polishing abrasive particles include one or more of nano-diamond suspension, nano-cerium oxide suspension, nano-aluminum oxide suspension, and nano-silicon oxide sol.

[0021] and / or, the polishing solvent comprises water;

[0022] And / or, the oxidant includes one or more of hydrogen peroxide, potassium permanganate, potassium ferrate, and sodium hypochlorite.

[0023] Compared with the prior art, the non-thermal global efficient planarization method of a single crystal diamond substrate described in the present invention has the following advantages:

[0024] 1. This application realizes non-thermal removal processing of diamond materials, avoiding equipment damage and operational risks caused by high temperature.

[0025] 2. This application introduces physical fields as a front-end modification process for superhard materials, achieving low-damage and uniform modification of diamond materials, greatly improving efficiency compared to traditional chemical mechanical polishing processes.

[0026] 3. This application achieves high-precision and high-efficiency processing of materials through low load and low speed, avoiding the risk of edge collapse and fragmentation of ultra-hard and brittle materials under high load and high speed conditions, and can improve the processing yield.

[0027] 4. The process of the present application is stable, which improves the oxidizability of the polishing liquid while ensuring the stability of the polishing liquid, thereby preventing the polishing liquid from becoming ineffective due to placement or long-term storage, and at the same time being able to meet the amplification needs in the existing polishing system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 AFM results after polishing in Example 1.

[0030] Figure 2 This is the AFM result after polishing of Example 2.

[0031] Figure 3 This is the AFM result after polishing of Example 3.

[0032] Figure 4 This is the AFM result of comparative example 1 after polishing.

[0033] Figure 5 This is the AFM result of comparative example 2 after polishing.

[0034] Figure 6 This is the AFM result of comparative example 3 after polishing.

[0035] Figure 7 This is the AFM result of comparative example 4 after polishing.

[0036] Figure 8 This is the C element fine spectrum of commercially available diamond surface.

[0037] Fig. 9 This is the fine spectrum of C element on the diamond surface after mechanical polishing in Example 3.

[0038] Fig.10 This is the fine spectrum of C element on the diamond surface after chemical mechanical polishing in Example 1. DETAILED DESCRIPTION

[0039] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0040] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0041] Example 1

[0042] Place the clean and dry diamond sheet on the three-dimensional mobile platform, and program the trajectory of the atmospheric direct jet plasma machine through a handheld programmer. The trajectory length is 5mm, the width is 5mm, the step distance is 1mm, the speed is 2mm / s, the nozzle height is 9mm, and the processing time is intermittent 10min (processing 1min, cooling 1min, repeated 10 times),

[0043] Then 800W of atmospheric plasma is released to treat the diamond surface to be processed.

[0044] The gas of the atmospheric plasma is air, and the gas pressure of the atmospheric plasma is 1MPa, and the processing pressure is 100kPa;

[0045] KMnO4 is dissolved in a diamond suspension to prepare a 500nm diamond suspension with KMnO4 oxidant added;

[0046] The model of diamond suspension is RXMDPM00500, which was purchased from Tianjin Ruixin Semiconductor Technology Co., Ltd.

[0047] After polishing for 3 h at 60 r / min with a 500 nm diamond suspension containing KMnO4 oxidant, the Ra was 0.075 nm and the MRR was 1.16 nm / min.

[0048] Example 2

[0049] Place the clean and dry diamond sheet on the three-dimensional mobile platform, and program the trajectory of the atmospheric direct jet plasma machine through a handheld programmer. The trajectory length is 5mm, the width is 5mm, the step distance is 1mm, the speed is 2mm / s, the nozzle height is 9mm, and the processing time is continuous for 10 minutes.

[0050] Then 800W of atmospheric plasma is released to treat the diamond surface to be processed.

[0051] The gas of the atmospheric plasma is air, and the gas pressure of the atmospheric plasma is 1MPa, and the processing pressure is 100kPa;

[0052] After polishing with 500nm diamond suspension at 60r / min for 3h, Ra was 0.259nm and MRR was 0.92nm / min.

[0053] The model of diamond suspension is RXMDPM00500, which was purchased from Tianjin Ruixin Semiconductor Technology Co., Ltd.

[0054] Example 3

[0055] A clean and dry diamond sheet is placed on a three-dimensional mobile platform, and the atmospheric direct injection plasma machine is programmed with a trajectory through a handheld programmer. The trajectory length is 5 mm, the width is 5 mm, the step distance is 1 mm, the speed is 2 mm / s, the nozzle height is 9 mm, and the processing time is intermittent 10 minutes (processing for 1 minute, cooling for 1 minute, repeated 10 times), and then 800 W of atmospheric plasma is released to treat the diamond surface to be processed.

[0056] The gas of the atmospheric plasma is air, and the gas pressure of the atmospheric plasma is 1MPa, and the processing pressure is 100kPa;

[0057] After polishing with 500nm diamond suspension at 60r / min for 3h, Ra was 0.171nm and MRR was 1.01nm / min.

[0058] The model of diamond suspension is RXMDPM00500, which was purchased from Tianjin Ruixin Semiconductor Technology Co., Ltd.

[0059] Comparative Example 1

[0060] Place the clean and dry diamond sheet on the three-dimensional mobile platform, and program the trajectory of the atmospheric direct jet plasma machine through a handheld programmer. The trajectory length is 5mm, the width is 5mm, the step distance is 1mm, the speed is 2mm / s, the nozzle height is 9mm, and the processing time is intermittent 10min (processing 1min, cooling 1min, repeated 10 times);

[0061] Then 600W of atmospheric plasma is released to treat the diamond surface to be processed.

[0062] The gas of the atmospheric plasma is air, and the gas pressure of the atmospheric plasma is 1MPa, and the processing pressure is 100kPa;

[0063] Polishing was performed with a 500 nm diamond suspension at 60 r / min for 20 min. After repeating the above modification and polishing steps three times, Ra was 0.574 nm and MRR was 0.20 nm / min.

[0064] The model of diamond suspension is RXMDPM00500, which was purchased from Tianjin Ruixin Semiconductor Technology Co., Ltd.

[0065] Comparative Example 2

[0066] A clean and dry diamond sheet is placed on a three-dimensional mobile platform, and the atmospheric direct injection plasma machine is programmed with a trajectory through a handheld programmer. The trajectory length is 5 mm, the width is 5 mm, the step distance is 1 mm, the speed is 2 mm / s, the nozzle height is 9 mm, and the processing time is intermittent 10 minutes (processing for 1 minute, cooling for 1 minute, repeated 10 times), and then 800 W of atmospheric plasma is released to treat the diamond surface to be processed.

[0067] The gas of the atmospheric plasma is air, and the gas pressure of the atmospheric plasma is 1MPa, and the processing pressure is 100kPa;

[0068] Polishing was performed with a 500 nm diamond suspension at 60 r / min for 20 min. After repeating the above modification and polishing steps three times, Ra was 0.946 nm and MRR was 1.93 nm / min.

[0069] The model of diamond suspension is RXMDPM00500, which was purchased from Tianjin Ruixin Semiconductor Technology Co., Ltd.

[0070] Comparative Example 3

[0071] Place the clean and dry diamond sheet on the three-dimensional mobile platform, and program the trajectory of the atmospheric direct jet plasma machine 0 through the handheld programmer. The trajectory length is 5mm, the width is 5mm, the step distance is 1mm, the speed is 2mm / s, the nozzle height is 9mm, and the processing time is intermittent 10min (processing 1min, cooling 1min, repeated 10 times), and then release 1000W atmospheric plasma to process the diamond surface to be processed.

[0072] The gas of the atmospheric plasma is air, and the gas pressure of the atmospheric plasma is 1MPa, and the processing pressure is 100kPa;

[0073] Polishing was performed with a 500 nm diamond suspension at 60 r / min for 20 min. After repeating the above modification and polishing steps three times, Ra was 2.160 nm and MRR was 2.70 nm / min.

[0074] The model of diamond suspension is RXMDPM00500, which was purchased from Tianjin Ruixin Semiconductor Technology Co., Ltd.

[0075] Comparative Example 4

[0076] The diamond surface was not subjected to amorphization treatment; the diamond surface without amorphization treatment was directly polished with 500nm diamond suspension at 60r / min for 3h, and the Ra was 0.418nm and the MRR was 0.09nm / min.

[0077] The model of diamond suspension is RXMDPM00500, which was purchased from Tianjin Ruixin Semiconductor Technology Co., Ltd.

[0078] It can be seen from the results of Example 2 and Example 3 that intermittent processing with atmospheric plasma is better than continuous processing. Although there is no significant difference in removal rate, the surface quality of continuous processing is poor. It can be seen from the results of Comparative Examples 1-3 that when the power is low (600W), it cannot effectively modify the diamond surface, resulting in low removal efficiency. When the power is too high (1000W), although the removal efficiency is significantly improved, it is difficult to obtain an excellent surface. This is because excessive plasma power will cause local defects, which are difficult to remove through subsequent processing. Therefore, the power requirement is closely related to the initial quality of the sample, the size of the sample, and the post-processing method. By comparing the results of Comparative Example 4 and Examples 2-3, it can be seen that compared with Comparative Example 4 without amorphization treatment, the Ra and MRR of Examples 2-3 after amorphization treatment are optimized, indicating that plasma treatment can significantly and successfully modify the diamond surface, significantly shorten the time for diamond to reach the target surface roughness, and greatly improve the processing efficiency. Compared with Example 1 and Example 3, the Ra and MRR after chemical mechanical polishing are better than mechanical polishing, and through Figure 8-10 XPS results show that both the diamond slices before treatment and the diamond slices after mechanical polishing have C sp2 , while the surface C of the diamond sheet after chemical mechanical polishing sp2 Can basically be removed.

[0079] In summary, the processing method provided by the present invention overcomes the problems of low removal rate and poor surface quality caused by the extremely high hardness and chemical inertness of diamond in the prior art.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A non-thermal global high-efficiency planarization method for a single crystal diamond substrate, characterized in that: The steps include: S1: using plasma to amorphize the surface of single crystal diamond to obtain modified single crystal diamond; S2: performing chemical mechanical polishing on the modified single crystal diamond obtained in step S1 to obtain a planarized single crystal diamond.

2. The method for non-thermal global high-efficiency planarization of a single crystal diamond substrate according to claim 1, characterized in that: The amorphization treatment in step S1 includes placing a clean and dry diamond sheet on a three-dimensional moving platform, exciting a gas with a high-frequency current to form a plasma, and using the plasma to amorphize the surface of the single-crystal diamond.

3. The non-thermal global high-efficiency planarization method of a single crystal diamond substrate according to claim 1 or 2, characterized in that: The plasma in step S1 is formed by an atmospheric direct injection plasma machine; And / or, the nozzle trajectory of the atmospheric direct injection plasma machine in step S1 is a rectangular trajectory.

4. The method for non-thermal global high-efficiency planarization of a single crystal diamond substrate according to claim 3, characterized in that: The rectangular track in step S1 has a width of 0-100 mm, a length of 0-100 mm, a step distance of 0-100 mm, and a speed of 0.1-100 mm / s.

5. The non-thermal global high-efficiency planarization method of a single crystal diamond substrate according to claim 1 or 2, characterized in that: The processing time of the amorphization treatment in step S1 is 0.1 to 10000 min, preferably, the processing time is 10 to 60 min.

6. A non-thermal global high-efficiency planarization method for a single crystal diamond substrate according to claim 1 or 2, characterized in that: The power of the plasma in step S1 is 300-1200 W, the gas pressure of the plasma is 0.02-1 MPa, the processing distance is 0.1-50 mm, and the processing pressure is 0.1-102 kPa; And / or, the working gas of the plasma includes one or more of oxygen, nitrogen, air, helium, and argon.

7. The non-thermal global high-efficiency planarization method of a single crystal diamond substrate according to claim 1, characterized in that: The load of the chemical mechanical polishing in step S2 is 0.01-10 kg / cm 2 , the speed is 0.1~1200r / min, and the time is 0.1~1000h.

8. The non-thermal global high-efficiency planarization method of a single crystal diamond substrate according to claim 1, characterized in that: The polishing liquid of the chemical mechanical polishing in step S2 includes a polishing solvent, polishing abrasive particles and an oxidant.

9. The method for non-thermal global high-efficiency planarization of a single crystal diamond substrate according to claim 8, characterized in that: The polishing abrasive particles include one or more of nano-diamond suspension, nano-cerium oxide suspension, nano-aluminum oxide suspension, and nano-silicon oxide sol; And / or, the polishing solvent includes water.

10. The non-thermal global high-efficiency planarization method of a single crystal diamond substrate according to claim 8, characterized in that: The oxidant includes one or more of hydrogen peroxide, potassium permanganate, potassium ferrate, and sodium hypochlorite.

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