Processing method and processing device

Abstract

To provide a processing method and a processing apparatus that can achieve processing with high efficiency and high accuracy despite a simple configuration in dry polishing for processing diamonds.SOLUTION: A processing apparatus 1 has a quartz surface plate 2, and a sample holder 4 that holds a single crystal diamond 3. The processing apparatus 1 has an argon gas supply unit 5 that supplies argon gas to a contact part of the quartz surface plate 2 and the single crystal diamond 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a processing method and a processing apparatus, and more particularly to a processing method and a processing apparatus that can realize highly efficient and highly accurate processing by dry polishing for processing diamond and the like, while having a simple configuration. [Background technology]

[0002] Diamond has a wide band gap of 5.4 eV, high thermal conductivity, and excellent dielectric breakdown field and charge mobility, making it a promising material for next-generation power semiconductor devices.

[0003] In order to fabricate semiconductor devices using diamond, it is said that processing technology is essential to finish the surface of the diamond substrate, which serves as the base for the device, to be atomically smooth and free of disturbances. However, because diamond is extremely hard and chemically stable, it is extremely difficult to process, and the development of processing technology has become a technical challenge.

[0004] For example, a conventional processing method is known in which chemical removal is performed by polishing with abrasive grains, such as chemical mechanical polishing, but this method has the problem that the removal rate is slow because it utilizes a chemical reaction in the polishing agent, and the processing efficiency is insufficient.

[0005] In contrast to the polishing in the above-mentioned solution environment, there is a processing method in an air environment that attempts to improve the processing efficiency without using abrasive grains.

[0006] For example, the inventors of the present application have proposed a processing method in which a polishing platen made of an inorganic oxide is irradiated with ultraviolet light or plasma to remove chemical contamination (organic contaminants) on the surface of the platen and to make the surface of the platen hydrophilic (to expose OH groups on the outermost surface) (see, for example, Patent Document 1).

[0007] In addition, the inventors of the present application have proposed a processing method in which, instead of using ultraviolet light or plasma, ozone gas is supplied near the contact point between the workpiece and the platen, which not only makes it easy to achieve sufficient processing accuracy but also significantly increases processing efficiency (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2014 / 034921 [Patent Document 2] JP 2018-125549 A Summary of the Invention [Problem to be solved by the invention]

[0009] However, there is a risk that the vacuum ultraviolet light and ozone gas used in the processing methods described in Patent Documents 1 and 2 may affect the human body. In addition, there is also a problem that the use of ozone gas requires an additional device for processing the ozone gas.

[0010] Furthermore, in conventional processing methods, in order to generate excited species with high chemical reactivity, it was necessary to supply high energy from an external source, such as by irradiating with ultraviolet rays, gamma rays, or electron beams, or by applying a high-voltage pulse discharge.

[0011] For this reason, conventional processing methods, including those described in Patent Documents 1 and 2, have room for improvement in terms of ensuring safety, the need to prepare dedicated devices and facilities, and the large environmental impact.

[0012] The present invention has been devised in view of the above points, and aims to provide a processing method and processing apparatus that can achieve highly efficient and high-precision processing in dry polishing for processing diamond and the like, while having a simple configuration. [Means for solving the problem]

[0013] [Processing method] In order to achieve the above object, the processing method of the present invention includes the steps of contacting a processing member made of an insulating material with an insulating workpiece, supplying argon gas to the contact site, and displacing the processing member while in contact with the workpiece.

[0014] Here, by bringing the processing member into contact with the workpiece and supplying argon gas to the contact area, the contact area can be placed in an argon gas environment. In other words, by supplying argon gas to the contact area, it is possible to localize argon gas in the area.

[0015] In addition, by displacing a processing member made of an insulating material while in contact with an insulating workpiece, static electricity can be generated at the contact site due to friction. With the generation of this static electricity, one of the processing member and the workpiece is positively charged and the other is negatively charged, and the contact site is under high voltage due to the difference in charge. When argon gas is supplied to the contact site, the argon gas becomes plasma and excited Ar atoms are generated. In addition, the excited Ar atoms can react with moisture in the air and generate highly chemically reactive excited species (OH radicals). These OH radicals enable stable physical and chemical processing of the workpiece.

[0016] Furthermore, as described above, the contact area is placed in an argon gas environment, so that the argon necessary for stable processing can be secured.

[0017] In the present invention, argon gas is supplied to the contact area between the processing member and the workpiece, i.e., the location where the workpiece is processed, and highly chemically reactive OH radicals are generated by utilizing the static electricity generated by friction, thereby achieving physically and chemically stable processing of the workpiece.

[0018] In addition, the processing member can be displaced while in contact with the workpiece, and one of the processing member and the workpiece can be positively charged and the other negatively charged by friction alone, without applying a voltage.This means that OH radicals can be generated using simple components, without using a separate device or circuit that applies a high voltage to the contact area.

[0019] Furthermore, when the processing component is made of any one of diamond, sapphire, quartz, glass, ceramics, rubber, plastic, and Teflon (registered trademark), and the workpiece is made of any one of diamond, sapphire, synthetic quartz, glass, and ceramics, sufficiently stable processing of the workpiece becomes possible.

[0020] Furthermore, when argon gas contains moisture, it promotes the tribochemical reaction that occurs on the friction surface between the processing member and the workpiece, generating oxides on the processing surface of the workpiece, which can be preferentially removed. As a result, in addition to processing using OH radicals, processing by tribochemical reactions is promoted, and the precision of the surface roughness can be further improved and processing efficiency can be improved.

[0021] [About the processing equipment] In addition, in order to achieve the above-mentioned object, the processing apparatus of the present invention includes a processing member made of an insulating material, a holding mechanism that holds an insulating workpiece in contact with the processing member, an argon gas supply unit that supplies argon gas to the contact site between the processing member and the workpiece, and a drive unit that displaces the processing member while the processing member and the workpiece are in contact with each other.

[0022] Here, the contact area can be placed in an argon gas environment by a holding mechanism that holds the insulating workpiece in contact with the workpiece and an argon gas supply unit that supplies argon gas to the contact area between the workpiece and the workpiece. In other words, by supplying argon gas to the contact area, it is possible to localize argon gas in the area.

[0023] In addition, a driving unit displaces a processing member made of an insulating material while in contact with an insulating workpiece, and generates static electricity by friction at the contact site. When this static electricity is generated, one of the processing member and the workpiece is positively charged and the other is negatively charged, and the contact site is under high voltage due to the difference in charge. When argon gas is supplied to the contact site, the argon gas becomes plasma and excited Ar atoms are generated. In addition, the excited Ar atoms can react with moisture in the air to generate highly chemically reactive excited species (OH radicals). These OH radicals enable stable physical and chemical processing of the workpiece.

[0024] Furthermore, as described above, the contact area is placed in an argon gas environment, so that the argon necessary for stable processing can be secured.

[0025] In the present invention, argon gas is supplied to the contact area between the processing member and the workpiece, i.e., the location where the workpiece is processed, and highly chemically reactive OH radicals are generated by utilizing the static electricity generated by friction, thereby achieving physically and chemically stable processing of the workpiece.

[0026] In addition, the processing member is displaced while in contact with the workpiece, and one of the processing member and the workpiece can be positively charged and the other negatively charged by friction alone, without applying a voltage.This makes it possible to generate OH radicals using simple members, without using a separate device or circuit that applies a high voltage to the contact site.

[0027] Furthermore, when the processing component is made of any one of diamond, sapphire, quartz, glass, ceramics, rubber, plastic, and Teflon (registered trademark), and the workpiece is made of any one of diamond, sapphire, synthetic quartz, glass, and ceramics, sufficiently stable processing of the workpiece becomes possible.

[0028] Furthermore, when argon gas contains moisture, it promotes the tribochemical reaction that occurs on the friction surface between the processing member and the workpiece, generating oxides on the processing surface of the workpiece, which can be preferentially removed. As a result, in addition to processing using OH radicals, processing by tribochemical reactions is promoted, and the precision of the surface roughness can be further improved and processing efficiency can be improved. Effect of the Invention

[0029] The processing method and processing apparatus to which the present invention is applied can realize highly efficient and highly accurate processing by dry polishing for processing diamond and the like, even with a simple configuration. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a schematic diagram for explaining a processing device to which the present invention is applied. [Diagram 2] 1 is a graph showing the relationship between the wavelength of light and the emission intensity in an example. [Diagram 3] 13 is a graph showing the relationship between the wavelength of light and the emission intensity in a comparative example. [Figure 4] 1 is a graph showing processing efficiency in an example and a comparative example. [Diagram 5] 1A shows data obtained by measuring the surface roughness of a portion of the processed area of ​​an embodiment using a non-contact shape measuring device, and FIG. 1B shows data obtained by measuring the surface roughness of a portion of the processed area of ​​a comparative example using a non-contact shape measuring device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Hereinafter, a mode for carrying out the present invention (hereinafter, referred to as "embodiments of the invention") will be described. 1 is a schematic diagram for explaining a processing device to which the present invention is applied, and the processing device 1 shown here has a quartz surface plate 2 and a sample holder 4 that holds a single crystal diamond 3. The processing device 1 also has an argon gas supply unit 5 that supplies argon gas to the contact area between the quartz surface plate 2 and the single crystal diamond 3. The single crystal diamond 3 is an example of an insulating workpiece.

[0032] The workpiece is polished by contacting the upper surface (upper surface in FIG. 1) of the quartz surface plate 2 with the single crystal diamond 3. The quartz surface plate 2 is an example of a processing member made of an insulating material.

[0033] The argon gas supply unit 5 is disposed above the quartz platen 2. The tip of the argon gas supply unit 5, i.e., the part from which the argon gas is discharged, is directed toward the contact portion between the quartz platen 2 and the single crystal diamond 3. This places the contact portion in an argon gas environment. The symbol G in the figure indicates argon gas.

[0034] Here, in this embodiment, the processing member is described as being formed of a quartz surface plate 2, but it is sufficient if it is made of an insulating material and is a material capable of processing the workpiece, and it does not necessarily have to be formed of a quartz surface plate 2. For example, it may be formed of diamond, sapphire, glass, ceramics, rubber, plastic, Teflon (registered trademark), or a constituent material made of these.

[0035] The quartz surface plate 2 is fixed onto a processing table 6 whose rotation speed is controllable, and is configured so that the quartz surface plate 2 can rotate in the direction indicated by the symbol A in FIG.

[0036] The sample holder 4 is configured to be rotatable in the direction indicated by the symbol B in Fig. 1 around a rotation axis 7 that is eccentric with respect to the rotation axis of the quartz platen 2. The sample holder 4 is configured to be swingable in the direction indicated by the symbol Z in Fig. 1.

[0037] Moreover, the sample holder 4, while holding the single crystal diamond 3, is lowered from above to a position where the single crystal diamond 3 comes into contact with the quartz platen 2. Note that the symbol Y in the figure indicates the direction in which the load is applied.

[0038] Here, in this embodiment, the workpiece held by the sample holder 4 is described by taking a single crystal diamond 3 as an example, but the workpiece is not limited to the single crystal diamond 3, and any material having insulating properties can be used. For example, diamond, polycrystalline diamond, CVD diamond, diamond-related materials such as DLC film, sapphire, alumina, SiC ceramics, Si3N4 ceramics, AIN, quartz, glass, and other hard and brittle materials may be used.

[0039] Hereinafter, a processing method using the processing device 1 configured as above will be described. That is, an example of a processing method to which the present invention is applied will be described.

[0040] In one example of a processing method to which the present invention is applied, argon gas is supplied from an argon gas supply unit 5 to the contact site between the quartz platen 2 and the single crystal diamond 3 while the quartz platen 2 and the sample holder 7 are rotated or rocked.

[0041] That is, while argon gas is supplied to the contact site between the quartz base plate 2 and the single crystal diamond 3, static electricity is generated by friction occurring at the contact site, and one of the quartz base plate 2 and the single crystal diamond 3 becomes positively charged and the other becomes negatively charged, and the difference in charge causes the contact site to be under high voltage.

[0042] Then, argon gas is supplied to the contact area, and the argon gas is turned into plasma under high voltage, generating excited Ar atoms. The excited Ar atoms also react with moisture in the air to generate OH radicals. The generated OH radicals act on the surface of the single crystal diamond 3, and the quartz platen 2 rotates with the upper surface of the single crystal diamond 3 in contact with the single crystal diamond 3, thereby physically and chemically removing the surface of the single crystal diamond 3.

[0043] As a modification of this embodiment, a method may be adopted in which the argon gas supplied from the argon gas supply unit contains water and is supplied to the contact portion between the processing member and the workpiece.

[0044] When argon gas contains water, it promotes the tribochemical reaction that occurs on the friction surface between the processing member and the workpiece, generating oxides on the processing surface of the workpiece, which can be preferentially removed. As a result, in addition to processing using OH radicals, processing by tribochemical reactions is promoted, and the precision of the surface roughness can be further improved and processing efficiency can be improved.

[0045] [effect] The processing method and processing device to which the present invention is applied can realize physically and chemically stable processing of the workpiece by simply supplying argon gas to the contact area between the processing member and the workpiece, i.e., the position where the workpiece is processed, and by utilizing the static electricity generated by friction between the insulating processing member and the workpiece, highly chemically reactive OH radicals can be generated. Therefore, there is no need to supply high energy from outside, and processing can be realized with low equipment costs, low processing costs, and low environmental impact.

[0046] Furthermore, a processing apparatus to which the present invention is applied can be easily constructed by simply arranging an argon gas supply unit in an existing apparatus.

[0047] Furthermore, since the processing method and processing apparatus to which the present invention is applied do not use abrasive grains, there is no need to carry out abrasive processing after processing.

[0048] Furthermore, when processing using abrasive grains, the abrasive grains must be supplied in the form of a slurry, which means that the processing components and workpieces become wet with the slurry, making it difficult for the temperature to rise and for processing to proceed smoothly. On the other hand, in the processing method to which the present invention is applied, since abrasive grains are not used and no slurry is supplied, the processing members and workpieces are in a dry state, and the temperature, including frictional heat, easily rises and chemical reactions easily proceed. In other words, it is possible to realize high-precision and high-efficiency processing of difficult-to-process materials.

[0049] Examples of the present invention and comparative examples will be described below. Note that the examples shown here are merely examples and do not limit the present invention.

[0050] [Examples and Comparative Examples] As the processing method of the embodiment of the present invention, processing was performed under the following conditions. First, as the processing method of the embodiment 1 of the present invention, a single crystal diamond (3 mm × 3 mm) was placed on a quartz surface plate as a workpiece at a pressure of 2 kg (22.2 kg / cm 2 The sample holder was pressed with a load of 1000 rpm, the quartz platen was rotated at a rotation speed of 250 rpm, and the sample holder was rotated at a rotation speed of 1000 rpm, a rocking distance of 3 mm, and a rocking speed of 0.1 mm / s. Argon gas (5 L / min) was also supplied from the argon gas supply to the contact area between the quartz platen and the single crystal diamond. Processing was carried out under these conditions for one hour. A comparative example was prepared by the same method as in the embodiment, except that argon gas was not supplied from the argon gas supply unit.

[0051] In the apparatus configuration of the processing method of the above-mentioned embodiment, a spectrometer was installed below the contact area between the quartz platen and the single crystal diamond to measure the wavelength and emission intensity of light generated when the quartz platen and the single crystal diamond were rubbed together. Furthermore, the processing efficiency was confirmed for the above-mentioned examples and comparative examples. Furthermore, for the above-mentioned Examples and Comparative Examples, the surface roughness of the single crystal diamond after processing was measured using a non-contact shape measuring device and evaluated.

[0052] Figure 2 shows the results of the light wavelength and emission intensity measured in the example, and Figure 3 shows the results of the light wavelength and emission intensity measured in the comparative example. In the graphs of Figures 2 and 3, the vertical axis represents the emission intensity, and the horizontal axis represents the wavelength.

[0053] As shown in Fig. 2, in the example, a peak of the emission spectrum of OH radicals was confirmed at a wavelength of 309 nm, as indicated by symbol A. In addition, in the example, a peak of the emission spectrum of excited Ar atoms was confirmed in the wavelength range of 700 to 800 nm, as indicated by symbol C. In addition, in the example, a peak of the emission spectrum of excited nitrogen atoms was confirmed at the position indicated by symbol B. In addition, as shown in Fig. 3, in the comparative example, a peak of the emission spectrum of excited nitrogen atoms was confirmed at the position indicated by symbol A.

[0054] The results of the processing efficiency of the Example and the Comparative Example are shown in Figure 4. In Figure 4, the graph of the results of the Example corresponds to "With Ar gas", and the graph of the results of the Comparative Example corresponds to "Without Ar gas". In Figure 4, the vertical axis indicates the processing efficiency.

[0055] The processing efficiency in the example was 1427 nm / h, which showed sufficient processing efficiency. On the other hand, the processing efficiency in the comparative example was 53 nm / h.

[0056] FIG. 5(a) shows the surface roughness of a portion of the processed region of the example, and FIG. 5(b) shows the surface roughness of a portion of the processed region of the comparative example.

[0057] As shown in Fig. 5(a), the arithmetic mean roughness (Ra) value in the measurement range of the processed surface in the example was 0.438 nm. Also, as shown in Fig. 5(b), the arithmetic mean roughness (Ra) value in the measurement range of the processed surface in the comparative example was 1.399 nm. Thus, the processed surface of the workpiece in the example was processed with higher accuracy than that in the comparative example. [Explanation of symbols]

[0058] 1 Processing equipment 2 Quartz surface plate 3. Single crystal diamond 4. Sample Holder 5 Argon gas supply unit 6 Processing table 7 Rotation Axis

Claims

1. a step of contacting a processing member made of an insulating material with a workpiece having insulating properties, supplying argon gas to a contact site, and polishing the workpiece with the processing member, causing the argon gas to become plasma at the contact site due to charging caused by friction between the processing member and the workpiece, generating excited Ar atoms, and the excited Ar atoms react with moisture in the air to generate OH radicals, The processed member is made of any one of diamond, sapphire, quartz, glass, and ceramics; The workpiece is made of any one of diamond, sapphire, synthetic quartz, glass, and ceramics. Processing method.

2. The processing member is displaced while in contact with the workpiece, and one of the processing member and the workpiece is positively charged and the other is negatively charged by friction alone, without applying a voltage. The processing method according to claim 1.

3. The argon gas contains moisture. The processing method according to claim 1 or 2.

4. A processed member made of an insulating material; a holding mechanism that holds an insulating workpiece in contact with the processing member; an argon gas supply unit for supplying argon gas to a contact portion between the processing member and the workpiece; a driving unit for polishing the workpiece by the processing member, The processed member is made of any one of diamond, sapphire, quartz, glass, and ceramics; The workpiece is made of any one of diamond, sapphire, synthetic quartz, glass, and ceramics; The argon gas is converted into plasma at the contact site by the electrification caused by friction between the processing member and the workpiece, generating excited Ar atoms, and the excited Ar atoms react with moisture in the air to generate OH radicals. Processing equipment.

5. The driving unit is configured to displace the processing member while in contact with the workpiece, and to positively charge one of the processing member and the workpiece and negatively charge the other by friction alone, without applying a voltage. The processing apparatus according to claim 4.

6. The argon gas contains moisture. The processing apparatus according to claim 5 or 6.

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