Processing method and processing device

Abstract

To provide a processing method and a processing device capable of achieving high-efficiency processing in dry polishing of processing a single-crystal diamond substrate.SOLUTION: A processing method comprises: a first step of fixing a single-crystal diamond substrate 3, rotating only a synthetic quartz surface plate 2, and causing the synthetic quartz surface plate 2 to perform relative motion in a direction in which the polishing rate of the single-crystal diamond substrate 3 is high; and a second step of rotating both the single-crystal diamond substrate 3 and the synthetic quartz surface plate 2 to cause relative motion therebetween. In both the first and second steps, the single-crystal diamond substrate 3 and the synthetic quartz surface plate 2 are in contact with each other, and nitrogen gas is supplied to the contact portion from a nitrogen gas supply unit 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a processing method and processing apparatus, and more particularly to a processing method and processing apparatus that can achieve highly efficient processing in dry polishing for processing single crystal diamond substrates. [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 single-crystal diamond substrate, which serves as the base for the device, to be atomically smooth and free of disturbances. However, single-crystal diamond substrates are extremely difficult to process due to their high hardness and chemical stability, 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 using abrasive grains, such as chemical mechanical polishing, but this method has the problem of slow removal speed and insufficient processing efficiency because it utilizes a chemical reaction in the polishing agent.

[0005] In contrast to the polishing in the solution environment described above, there is a processing method in an atmospheric environment that attempts to improve 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 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 inventor of the present application has proposed a processing method that improves processing efficiency by using nitrogen gas instead of ultraviolet light or plasma and supplying it to the contact point between the workpiece and the processing member (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2014 / 034921 [Patent Document 2] Japanese Patent Publication No. 2021-000683 Summary of the Invention [Problem to be solved by the invention]

[0009] However, although the processing methods described in Patent Documents 1 and 2 can increase the processing efficiency from several nm / h with conventional methods to several μm / h, further improvement in processing efficiency is required for practical use of diamond semiconductors.

[0010] 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 processing in dry polishing of single crystal diamond substrates. [Means for solving the problem]

[0011] [Processing method] In order to achieve the above object, the processing method of the present invention comprises a first step of supplying nitrogen gas to the contact area between a processing member made of an insulating material and a workpiece made of single crystal diamond, while the workpiece is fixed and, while the processing member is in contact with the workpiece, relatively displacing the processing member in a direction that results in a higher polishing rate for the workpiece; and a second step of, after the first step, supplying nitrogen gas to the contact area between the processing member and the workpiece and, while the processing member is in contact with the workpiece, relatively displacing both the processing member and the workpiece.

[0012] In the first step, nitrogen gas is supplied to the contact area between the insulating material and the single-crystal diamond workpiece, placing the contact area in a nitrogen gas environment. In other words, supplying nitrogen gas to the contact area makes it possible to localize the nitrogen gas in the area.

[0013] Furthermore, in the first step, the workpiece is fixed, and while the processing member is in contact with the workpiece, the processing member is relatively displaced in the direction of the workpiece where the polishing rate is higher, thereby efficiently wearing down the processing surface of the workpiece. That is, by relatively displacing the processing member in the direction of the workpiece where the polishing rate is higher, the amount of wear on the processing surface can be increased, and the processing efficiency of the processing surface can be improved.

[0014] Furthermore, in the first step, nitrogen gas is supplied to the contact area between the processing member and the workpiece, and the workpiece is fixed and displaced relative to the workpiece in the direction of the higher polishing rate while in contact with the workpiece. When the processing member and the workpiece are in contact, fixed, and displaced relative to each other, electrons are emitted from the newly frictioned surface of the processing member, and charge transfer (frictional charging) occurs between the processing member and the workpiece, resulting in discharge in the air drawn into the contact area. The excited nitrogen and electrons generated by this friction and discharge act as etching seeds for the single-crystal diamond substrate, removing the diamond from the workpiece surface by etching. Furthermore, supplying nitrogen gas to the contact area facilitates the generation of excited nitrogen and electrons that serve as etching seeds, thereby more efficiently abrading the single-crystal diamond substrate.

[0015] In the second step, nitrogen gas is supplied to the contact area between the workpiece and the processed member, thereby placing the contact area in a nitrogen gas environment. In other words, supplying nitrogen gas to the contact area makes it possible to localize the nitrogen gas in the area.

[0016] In the second step, after the first step, nitrogen gas is supplied to the contact area between the processing member and the workpiece, and the processing member and the workpiece are displaced relative to each other while the processing member is in contact with the workpiece, thereby wearing down and smoothing the surface of the workpiece that was worn down in the first step. Furthermore, supplying nitrogen gas to the contact area can increase processing efficiency.

[0017] In addition, in the first step, the unevenness of the processing surface of the processing member is transferred to the processing surface of the workpiece, and in the second step, the unevenness transferred to the processing surface and the unevenness of the processing surface are reduced, and if the processing surface is smoothed, the unevenness of the processing surface of the processing member can be reflected on the processing surface in the first step, and the processing surface can be worn. Furthermore, thereafter, in the second step, the unevenness of the processing surface during friction is reduced, and the reduction of the unevenness of the processing surface progresses, and the smoothing of the processing surface can progress.

[0018] Furthermore, when the combination of the first step treatment and the second step treatment is carried out multiple times, the work surface of the workpiece can be further worn down, and smoothed even further.

[0019] Furthermore, when a workpiece that has undergone the first and second steps is subjected to the next first step, if the unevenness of the processed surface that was reduced in the previous second step is transferred to the processed surface, unevenness that is smaller than the unevenness transferred in the previous first step will be transferred to the processed surface.

[0020] Furthermore, if the reduction of the irregularities transferred to the work surface and the irregularities on the work surface progresses in the second process performed following the first process, and the work surface becomes even smoother, the surface roughness of the work surface can be improved even more sufficiently. In other words, by repeating the first and second processes, the irregularities on the work surface and the work surface become gradually smaller, and the surface of the work surface processed by the processing member can be finished to be even smoother.

[0021] Furthermore, in the first step, if the speed at which the machining members are relatively displaced is increased so as to promote the generation of excited nitrogen species and the wear of the work surface of the workpiece, the increased speed causes further wear of the work surface of the workpiece, thereby further improving the machining efficiency.

[0022] Furthermore, in the first step, if the load that brings the processing member into contact with the workpiece is increased so as to promote the generation of excited nitrogen species and the wear of the workpiece surface, the workpiece surface is further worn as the load increases, thereby further improving the processing efficiency.

[0023] Furthermore, in the second step, if nitrogen gas is supplied to the contact site while the processing member is kept in contact with the workpiece, the second step can be performed continuously following the first step, thereby minimizing the time from the start of the first step to the completion of the second step.

[0024] Furthermore, in the second step, if the processing member is brought into contact with the workpiece again and nitrogen gas is supplied to the contact site, the processing up to the first step can be completed once, and the processing of the second step can be carried out at the desired timing.

[0025] Furthermore, when the processing member is made of any one of synthetic quartz, sapphire, ceramics, glass, single crystal diamond, polycrystalline diamond, and diamond-like carbon (DLC) film, sufficient processing with improved processing efficiency becomes possible for single crystal diamond substrates.

[0026] [About the processing equipment] Furthermore, in order to achieve the above-mentioned object, the processing apparatus of the present invention comprises a processing member made of an insulating material, a holding mechanism that holds a workpiece made of single crystal diamond so that it can come into contact with the processing member, a nitrogen gas supply unit that supplies nitrogen gas to the contact site between the processing member and the workpiece, a drive unit that relatively displaces at least one of the processing member and the workpiece while the processing member and the workpiece are in contact, and a control unit that performs a first control that controls the nitrogen gas supply unit and the drive unit to supply nitrogen gas to the contact site between the processing member and the workpiece, while fixing the workpiece and relatively displacing the processing member in a certain direction with respect to the workpiece while the processing member is in contact with the workpiece, and a second control that brings the processing member into contact with the workpiece, supplies nitrogen gas to the contact site, and relatively displaces both the processing member and the workpiece while the processing member is in contact with the workpiece.

[0027] Here, the contact area can be placed in a nitrogen gas environment by using a processing member made of an insulating material, a holding mechanism that holds the workpiece made of single crystal diamond in contact with the processing member, and a nitrogen gas supply unit that supplies nitrogen gas to the contact area between the processing member and the workpiece. In other words, by supplying nitrogen gas to the contact area, it is possible to localize nitrogen gas in that area.

[0028] Furthermore, friction can be generated between the processing member and the workpiece by a drive unit that relatively displaces at least one of the processing member and the workpiece while the processing member and the workpiece are in contact with each other.

[0029] Furthermore, the control unit controls the drive unit to perform a first control in which the workpiece is fixed and the processing member is in contact with the workpiece, and the processing surface of the workpiece is displaced in a fixed direction relative to the workpiece, thereby efficiently wearing down the processing surface of the workpiece. That is, by the control unit controlling the drive unit to relatively displace the processing member in a direction that provides a higher polishing rate for the workpiece, the amount of wear on the processing surface can be increased, and the processing efficiency of the processing surface can be improved.

[0030] Furthermore, the control unit controls the nitrogen gas supply unit and the drive unit to supply nitrogen gas to the contact area between the processing member and the workpiece, while the workpiece is fixed and the processing member is displaced relative to the workpiece in a certain direction while in contact with the workpiece. This first control further accelerates the wear of the workpiece's processing surface. Specifically, when the control unit controls the drive unit to fix the workpiece and displace the processing member relative to the workpiece while in contact with the workpiece, electrons are emitted from the newly frictioned surface of the processing member, and charge transfer (frictional charging) occurs between the processing member and the workpiece, resulting in discharge in the air drawn into the contact area. The excited nitrogen and electrons generated by this friction and discharge act as etching seeds for the single-crystal diamond substrate, allowing the diamond on the workpiece surface to be removed by etching. Furthermore, the control unit controls the nitrogen gas supply unit to supply nitrogen gas to the contact area, facilitating the generation of excited nitrogen and electrons that serve as etching seeds, thereby more efficiently wearing away the single-crystal diamond substrate.

[0031] Furthermore, by performing a second control in which the control unit supplies nitrogen gas to the contact area between the processing member and the workpiece and relatively displaces both the processing member and the workpiece while the processing member is in contact with the workpiece, the processing surface of the workpiece that was worn in the first step can be worn and smoothed. Furthermore, by supplying nitrogen gas to the contact area, processing efficiency can be improved.

[0032] Furthermore, in the first control, the unevenness of the processing surface of the processing member is transferred to the processing surface of the workpiece, and in the second control, the unevenness transferred to the processing surface and the unevenness of the processing surface are reduced, and when the processing surface is smoothed, the unevenness of the processing surface of the processing member is reflected on the processing surface in the first control, and the processing surface can be worn. Furthermore, in the second control, the unevenness of the processing surface during friction is reduced, and the reduction of the unevenness of the processing surface is advanced, and the smoothing of the processing surface can be advanced.

[0033] Furthermore, when the control unit causes the workpiece to be processed multiple times by combining the first process and the second process, the workpiece surface can be further worn down, further progressing the smoothing.

[0034] Furthermore, when the processing member is made of any one of synthetic quartz, sapphire, ceramics, glass, single crystal diamond, polycrystalline diamond, and diamond-like carbon (DLC) film, sufficient processing with improved processing efficiency becomes possible for single crystal diamond substrates. [Effects of the Invention]

[0035] The processing method and processing apparatus to which the present invention is applied can realize highly efficient processing in dry polishing for processing single crystal diamond substrates. [Brief explanation of the drawings]

[0036] [Figure 1] FIG. 1(a) is a schematic diagram for explaining a processing device to which the present invention is applied, and FIG. 1(b) is a schematic perspective view showing a synthetic quartz surface plate and its peripheral structure. [Figure 2] (a) is a schematic diagram showing a state in which a single crystal diamond (100) substrate is fixed and a synthetic quartz surface plate is moved relatively in the direction of a higher polishing rate of the single crystal diamond (100) substrate, and (b) is a schematic diagram showing a state in which a single crystal diamond (100) substrate is fixed and a synthetic quartz surface plate is moved relatively in the direction of a lower polishing rate of the single crystal diamond (100) substrate. [Figure 3] Graph (a) shows the removal rates for a process in which a single-crystal diamond (100) substrate is fixed, a synthetic quartz surface plate is rotated, and nitrogen gas is supplied, in which the work surface is polished in a direction with a higher polishing rate and a direction with a lower polishing rate. Graph (b) shows the removal rates for a process in which a single-crystal diamond (100) substrate is fixed, a synthetic quartz surface plate is rotated, and nitrogen gas is not supplied, in which the work surface is polished in a direction with a higher polishing rate and a direction with a lower polishing rate. [Figure 4] This graph shows the removal rates for processes in which a single crystal diamond (100) substrate is fixed, a synthetic quartz surface plate is rotated, and nitrogen gas is supplied, with the work surface being polished in the direction of the higher polishing rate and the direction of the lower polishing rate, and for processes in which a single crystal diamond (100) substrate and a synthetic quartz surface plate are rotated and nitrogen gas is supplied, with the work surface being polished in the direction of the higher polishing rate. [Figure 5] (a) is a laser microscope image of a synthetic quartz surface plate that has been polished by lapping with #320 hard abrasive grains, (b) is data on the surface roughness of a portion of the processed area of ​​a single-crystal diamond (100) substrate measured using a non-contact shape measuring device, and (c) is the roughness curve of line A-A' in Figure 5(a). [Figure 6] (a) is a laser microscope image of a synthetic quartz surface plate that has been polished by lapping with #1200 hard abrasive grains, (b) is data on the surface roughness of a portion of the processed area of ​​a single-crystal diamond (100) substrate measured using a non-contact shape measuring device, and (c) is the roughness curve of line B-B' in Figure 6(a). [Figure 7] (a) is a schematic diagram showing the positional relationship between the processing surface of the synthetic quartz surface plate and the single crystal diamond (100) substrate in the first step, and (b) is a schematic diagram showing the positional relationship between the processing surface of the synthetic quartz surface plate and the single crystal diamond (100) substrate in the second step. [Figure 8] (a) shows data obtained by measuring the surface roughness of a localized area of ​​a single-crystal diamond (100) substrate after the first step using a non-contact profilometer, and (b) shows data obtained by measuring the surface roughness of a localized area of ​​a single-crystal diamond (100) substrate after the second step using a non-contact profilometer. [Figure 9] (a) is the emission spectrum near the contact point when the relative speed of the synthetic quartz surface plate to the single crystal diamond substrate is changed, and (b) is a graph showing the removal rate of processing when the relative speed of the synthetic quartz surface plate to the single crystal diamond substrate is changed. [Figure 10](a) is the emission spectrum near the contact point when the load pressing the single-crystal diamond substrate against the synthetic quartz surface plate is changed, and (b) is a graph showing the removal rate of processing when the load pressing the single-crystal diamond substrate against the synthetic quartz surface plate is changed. DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, modes for carrying out the present invention (hereinafter referred to as "embodiments of the invention") will be described. Figure 1(a) is a schematic diagram for explaining a processing apparatus to which the present invention is applied, showing the apparatus in a plan view. The processing apparatus 1 shown in Figure 1(a) has a synthetic quartz surface plate 2 and a sample holder 4 that holds a single-crystal diamond substrate 3. The processing apparatus 1 also has a nitrogen gas supply unit 5 that supplies nitrogen gas to the contact area between the synthetic quartz surface plate 2 and the single-crystal diamond substrate 3.

[0038] The synthetic quartz surface plate 2 is disposed so as to be oriented substantially parallel to the vertical direction (see FIG. 1(a)). The synthetic quartz surface plate 2 is an example of a processed member made of an insulating material.

[0039] 1(b), the single crystal diamond substrate 3 is placed in a position facing the processing surface 2a of the synthetic quartz surface plate 2 via a sample holder 4. By adjusting the position of this sample holder 4, the processing surface of the single crystal diamond substrate 3 can be held in contact with the processing surface 2a.

[0040] The surface to be processed of the single crystal diamond substrate 3 is brought into contact with the processing surface 2a of the synthetic quartz surface plate 2, and the surface to be processed is processed.

[0041] The nitrogen gas supply unit 5 is arranged so that its tip 5a, which supplies nitrogen gas, is directed toward the contact area between the processing surface 2a of the synthetic quartz surface plate 2 and the surface to be processed of the single-crystal diamond substrate 3 (see FIG. 1(a)). This places the contact area in a nitrogen gas environment.

[0042] Here, in this embodiment, the processing member is described as being formed of a synthetic quartz surface plate 2, but it is sufficient if it is made of an insulating material and is a material that can process the workpiece, and it does not necessarily have to be formed of a synthetic quartz surface plate 2. For example, it may be formed of sapphire, ceramics, glass, single crystal diamond, polycrystalline diamond, diamond-like carbon (DLC) film, or a constituent material made of any of these.

[0043] In addition, the synthetic quartz surface plate 2 is fixed on a processing table 6 whose rotation speed can be controlled, and is configured so that the synthetic quartz surface plate 2 can rotate in the direction indicated by symbol R1 in Figure 1(a) by rotating the processing table 6.

[0044] The sample holder 4 is configured to be rotatable in the direction indicated by the symbol R2 in FIG. 1(a) around a rotation axis 7 that is eccentric with respect to the rotation axis of the synthetic quartz surface plate 2.

[0045] Furthermore, the sample holder 4 is configured to be able to move, while holding the single crystal diamond substrate 3, to a position where the single crystal diamond substrate 3 and the synthetic quartz surface plate 2 come into contact with each other, and the amount of movement can be adjusted to apply a load to the single crystal diamond substrate 3.

[0046] The processing apparatus 1 also has a control unit (not shown) that controls the rotation of the processing table 6, the horizontal and vertical movement of the sample holder 4 toward the synthetic quartz surface plate 2, and the rotation of the rotation shaft 7.

[0047] That is, this control unit can control whether or not to rotate and the rotation speed of the processing table 6 and the rotation axis 7. This control unit can also control the contact state between the processing surface of the single crystal diamond substrate 3 held by the sample holder 4 and the processing surface 2a of the synthetic quartz surface plate 2, as well as the load applied to the single crystal diamond substrate 3.

[0048] A processing method using the processing device 1 configured as above will be described below. That is, an example of a processing method to which the present invention is applied will be described.

[0049] An example of a processing method to which the present invention is applied includes a first step in which the single crystal diamond substrate 3 is fixed and only the synthetic quartz surface plate 2 is rotated, and the synthetic quartz surface plate 2 is moved relative to the single crystal diamond substrate 3 in the direction of the highest polishing rate, and a second step in which the single crystal diamond substrate 3 and the synthetic quartz surface plate 2 are each rotated and moved relative to each other.

[0050] In both the first and second steps, the single crystal diamond substrate 3 and the synthetic quartz surface plate 2 are in contact with each other, and nitrogen gas is supplied from a nitrogen gas supply unit 5 to the contact area.

[0051] More specifically, in the first step, the work surface of the single-crystal diamond substrate 3 held by the sample holder 4 is brought into contact with the work surface 2a of the synthetic quartz surface plate 2 at a constant pressure. The single-crystal diamond substrate 3 is also positioned so that the direction of relative movement between the work surface and the work surface 2a of the processing member when the work surface 2a rotates coincides with the direction in which the polishing rate of the work surface is high (the direction in which polishing is easiest).

[0052] In the first step, the rotation axis 7 is not rotated, and the single crystal diamond substrate 3 is fixed and placed in contact with the processing surface 2a of the synthetic quartz surface plate 2. Then, from this state, the synthetic quartz surface plate 2 is rotated, and nitrogen gas is supplied from the nitrogen gas supply unit 5 to the contact area.

[0053] In this first step, the processing surface 2a of the synthetic quartz surface plate 2 comes into contact with the processing surface of the single crystal diamond substrate 3, and only the synthetic quartz surface plate 2 rotates, so that the unevenness of the processing surface 2a is transferred to the processing surface, causing the processing surface to wear.

[0054] Furthermore, since the direction of relative movement between the workpiece surface and the workpiece surface 2a of the workpiece member when the workpiece surface 2a rotates coincides with the direction in which the polishing rate of the workpiece surface is high, the amount of wear on the workpiece surface is greater compared to a state in which the direction of relative movement between the workpiece surface and the workpiece surface 2a of the workpiece member when the workpiece surface 2a rotates coincides with the direction in which the polishing rate of the workpiece surface is low.

[0055] In the first step, the machining surface 2a of the synthetic quartz surface plate 2 and the machining surface of the single-crystal diamond substrate 3 come into contact and undergo relative displacement at the contact site, causing charge transfer (frictional electrification) at the contact site. Electrons are then emitted from the nascent friction surface of the machining member, and discharge occurs in the air at the contact site due to charge transfer (frictional electrification), exciting nitrogen in the air and nitrogen gas 5 supplied from the nitrogen gas supply unit 5.

[0056] The excited nitrogen and electrons generated at the contact site act as highly chemically reactive etching species on the work surface of the single-crystal diamond substrate 3, removing the diamond from that area, thereby further accelerating the wear of the work surface.

[0057] Subsequently, in the second step, the surface to be processed of the single crystal diamond substrate 3 held by the sample holder 4 is brought into contact with the processing surface 2a of the synthetic quartz surface plate 2 at a constant pressure. In addition, the rotation shaft 7 is rotated, and the synthetic quartz surface plate 2 is also rotated, and nitrogen gas is supplied from the nitrogen gas supply unit 5 to the contact area.

[0058] In this second step, the unevenness of the processing surface 2a of the synthetic quartz surface plate 2 during friction is reduced, thereby reducing the unevenness of the processing surface of the single-crystal diamond substrate 3 that was worn in the first step, and the processing surface can be further worn and smoothed. In addition, supplying nitrogen gas to the contact area can further promote wear of the processing surface, thereby improving processing efficiency.

[0059] In this way, in the processing method to which the present invention is applied, by carrying out the first and second steps, the surface to be processed of the single-crystal diamond substrate 3 is largely worn away, enabling highly efficient processing. In addition, the surface to be processed of the single-crystal diamond substrate 3 can be smoothed, and the surface roughness can be improved.

[0060] Furthermore, in the processing method to which the present invention is applied, the processing surface can be further worn and smoothed by repeatedly performing the first and second steps on the single-crystal diamond substrate 3. This repeated processing particularly contributes to improving the surface roughness of the processing surface.

[0061] In this embodiment, in which the single crystal diamond substrate 3 is repeatedly subjected to the first and second steps, the unevenness of the processing surface 2a of the synthetic quartz surface plate 2 is reduced, and the surface of the processing surface of the single crystal diamond substrate 3, which is processed in contact with the synthetic quartz surface plate 2, becomes smoother.

[0062] [effect] The processing method and processing apparatus to which the present invention is applied can achieve highly efficient processing of the single crystal diamond substrate 3 by processing the single crystal diamond substrate 3 using a synthetic quartz surface plate 2 while the single crystal diamond substrate 3 is fixed, and by processing while both the single crystal diamond substrate 3 and the synthetic quartz surface plate 2 are rotated.

[0063] 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.

[0064] [Relationship between polishing direction and wear rate for single-crystal diamond (100) substrate] Below, we investigated the relationship between the polishing direction of friction force and the wear rate against the work surface of a single-crystal diamond (100) substrate. Single-crystal diamond substrates include single-crystal diamond (100), single-crystal diamond (110), and single-crystal diamond (111) substrates, and in the following content, a single-crystal diamond (100) substrate was used. In this study, using the above-mentioned processing device 1, as shown in the lower diagram of FIG. 2(a), when the processing surface 2a rotates with respect to the processing surface of the single crystal diamond (100) substrate 3, the relative movement direction of the processing surface 2a of the processing member and the processing surface 2a of the processing member is the direction in which the polishing rate of the processing surface is high. <100> The single crystal diamond (100) substrate 3 was placed so that the direction of the surface to be processed (the direction that is easy to polish) was the sample 1. As shown in the lower diagram of Figure 2(b), when the processing surface 2a rotates with respect to the surface to be processed of the single crystal diamond (100) substrate 3, the relative movement direction of the surface to be processed and the processing surface 2a of the processing member is the direction in which the polishing rate of the surface to be processed is low. <110> The sample 2 was prepared by placing a single crystal diamond (100) substrate 3 so that the (100) surface was in the direction that was difficult to polish.

[0065] In addition, this study was carried out under the following conditions: A single crystal diamond (100) substrate 3 (3 mm x 3 mm) was pressed with a load of 14 N, the sample holder 4 was fixed, and the synthetic quartz surface plate 2 was rotated at a rotation speed of 937.5 rpm (relative speed: 3.93 m / s). Nitrogen gas (5 L / min) was supplied from the nitrogen gas supply unit 5 to the contact area between the synthetic quartz surface plate 2 and the single crystal diamond (100) substrate 3. Processing was carried out under these conditions for 5 minutes. The removal rate, which indicates the amount of wear, was calculated by comparing the weight change of the workpiece before and after processing with the specific gravity of diamond, 3.52 g / cm. 2 was calculated from

[0066] Samples 1 and 2 were processed under the same conditions as above, but without supplying nitrogen gas. Sample 1 was also processed under the same conditions as above, with the sample holder 4 rotated at a rotation speed of 937.5 rpm.

[0067] Figure 3(a) shows the results of processing Sample 1 and Sample 2 when the sample holder 4 was fixed and nitrogen gas was supplied. The vertical axis represents the removal rate (μm / h), which indicates the amount of wear on the processed surface of the single-crystal diamond (100) substrate 3. The graph on the left shows the results for Sample 1, and the graph on the right shows the results for Sample 2.

[0068] As shown in Figure 3(a), the removal rate was 151.52 μm / h for Sample 1 and 8.33 μm / h for Sample 2. A significant increase in the amount of wear was confirmed for Sample 1 compared to Sample 2.

[0069] Figure 3(b) shows the results of processing Sample 1 and Sample 2 when the sample holder 4 was fixed and no nitrogen gas was supplied. The vertical axis represents the removal rate (μm / h), which indicates the amount of wear on the processed surface of the single-crystal diamond (100) substrate 3. The graph on the left shows the results for Sample 1, and the graph on the right shows the results for Sample 2.

[0070] As shown in Figure 3(b), the removal rate was 40.15 μm / h for Sample 1 and 7.58 μm / h for Sample 2. An increase in the amount of wear was confirmed for Sample 1 compared to Sample 2, but the removal rate for Sample 1 was smaller than that for processing with nitrogen gas supply shown in Figure 3(a).

[0071] Figure 4 shows the results of machining samples 1 and 2 when the sample holder 4 was fixed and nitrogen gas was supplied, as well as the results of machining sample 1 when the sample holder 4 was also rotated and nitrogen gas was supplied. The vertical axis is the removal rate (μm / h), which indicates the amount of wear on the surface of the single crystal diamond 3 being machined. The graph on the left shows the results for sample 1 when the sample holder 4 was fixed, the graph in the middle shows the results for sample 2 when the sample holder 4 was fixed, and the graph on the right shows the results for sample 1 when the sample holder 4 was also rotated.

[0072] As shown in Figure 4, the removal rate for Sample 1 in which the sample holder 4 was also rotated was 8.33 μm / h. In other words, when comparing the processing of Sample 1 in which the sample holder 4 was fixed with the processing of Sample 1 in which the sample holder 4 was also rotated, a significant increase in the amount of wear was confirmed in the processing of Sample 1 in which the sample holder 4 was fixed.

[0073] [Relationship between the surface roughness of the polishing table and the surface roughness of the single-crystal diamond (100) substrate] Next, the relationship between the surface roughness of the polishing platen and the surface roughness of the single crystal diamond (100) substrate was investigated. In this study, using the above-mentioned processing device 1, a single crystal diamond (100) substrate 3 was processed on a synthetic quartz surface plate 2 (the surface plate with larger surface irregularities on the processed surface) that had been lapped and polished with #320 hard abrasive grains, and this was used as sample 3. Also, a single crystal diamond (100) substrate 3 was processed on a synthetic quartz surface plate 2 (the surface plate with smaller surface irregularities on the processed surface) that had been lapped and polished with #1200 hard abrasive grains, and this was used as sample 4. Figure 5(a) shows a laser microscope photograph of a synthetic quartz surface plate that has been lapped and polished with #320 hard abrasive grains, and Figure 5(c) shows the roughness curve along line A-A' in Figure 5(a). Figure 6(a) shows a laser microscope photograph of a synthetic quartz surface plate that has been lapped and polished with #1200 hard abrasive grains, and Figure 6(c) shows the roughness curve along line B-B' in Figure 6(a).

[0074] In this study, processing was carried out under the following conditions: A single-crystal diamond (100) substrate 3 (3 mm x 3 mm) was pressed with a load of 14 N, the sample holder 4 was fixed, and the synthetic quartz surface plate 2 was rotated at a rotation speed of 937.5 rpm (relative speed: 3.93 m / s). Nitrogen gas (5 L / min) was supplied from the nitrogen gas supply unit 5 to the contact area between the synthetic quartz surface plate 2 and the single-crystal diamond (100) substrate 3. Processing was carried out under these conditions for 5 minutes.

[0075] Figure 5(b) shows data obtained by measuring the surface roughness of a portion of the processing area of ​​the single crystal diamond (100) substrate 3 in sample 3 using a non-contact profilometer, and Figure 6(b) shows data obtained by measuring the surface roughness of a portion of the processing area of ​​the single crystal diamond (100) substrate 3 in sample 4 using a non-contact profilometer.

[0076] As shown in Figures 5(b) and 6(b), the surface roughness of the processed surface of the single crystal diamond (100) substrate 3 processed using the synthetic quartz surface plate 2 with the smaller surface roughness (arithmetic mean roughness Ra value in the measurement range: 0.008 μm) was improved compared to the processed surface of the single crystal diamond (100) substrate 3 processed using the synthetic quartz surface plate 2 with the larger surface roughness (arithmetic mean roughness Ra value in the measurement range: 0.201 μm).

[0077] [Example 1] The processing method of Example 1 of the present invention was carried out under the following conditions. First, in the processing method of Example 1 of the present invention, in the first step, a single-crystal diamond (100) substrate 3 (3 mm × 3 mm) was pressed against a synthetic quartz surface plate 2 with a load of 14 N, the sample holder 4 was fixed, and the synthetic quartz surface plate 2 was rotated at a rotation speed of 937.5 rpm (relative speed: 3.93 m / s). Nitrogen gas (5 L / min) was supplied from a nitrogen gas supply unit 5 to the contact area between the synthetic quartz surface plate 2 and the single-crystal diamond (100) substrate 3. Processing was carried out under these conditions for 5 minutes. Furthermore, after the first step, in the second step, a single-crystal diamond (100) substrate 3 (3 mm × 3 mm) was pressed against the synthetic quartz surface plate 2 with a load of 14 N, the sample holder 4 was rotated at a rotation speed of 937.5 rpm, and the synthetic quartz surface plate 2 was also rotated at a rotation speed of 937.5 rpm. Furthermore, nitrogen gas (5 L / min) was supplied from the nitrogen gas supply unit 5 to the contact area between the synthetic quartz surface plate 2 and the single crystal diamond (100) substrate 3. Under these conditions, processing was carried out for 20 minutes. FIG. 7(a) shows the positional relationship between the processing surface 2a of the synthetic quartz surface plate 2 and the single crystal diamond (100) substrate 3 in the first step, and FIG. 7(b) shows the positional relationship between the processing surface 2a of the synthetic quartz surface plate 2 and the single crystal diamond (100) substrate 3 in the second step.

[0078] Figure 8(a) shows data obtained by measuring the surface roughness of a local area of ​​a single crystal diamond (100) substrate 3 after the first step using a non-contact profilometer, and Figure 8(b) shows data obtained by measuring the surface roughness of a local area of ​​a single crystal diamond (100) substrate 3 after the second step using a non-contact profilometer.

[0079] As shown in Figure 8(a), after the first step, unevenness was formed on the work surface of the single crystal diamond (100) substrate 3. This unevenness on the work surface was formed by transferring the uneven state of the work surface 2a of the synthetic quartz surface plate 2.

[0080] Furthermore, as shown in Figure 8(b), after the second step, the surface irregularities of the processed surface of the single-crystal diamond (100) substrate 3 were reduced and smoothed. In other words, the surface roughness of the processed surface was improved. After a total of 25 minutes of short processing time, consisting of 5 minutes of processing in the first step and 20 minutes of processing in the second step, the arithmetic mean roughness Ra in the measurement range was 0.793 nm (see Figure 8(b)).

[0081] During the second step, the reduction in the unevenness of the processed surface of the single crystal diamond (100) substrate 3 was achieved by smoothing the processed surface 2a of the synthetic quartz surface plate 2 during friction.

[0082] Next, based on the processing method of Example 1 described above, processing was carried out as follows, with the relative speed of the synthetic quartz surface plate 2 relative to the single crystal diamond substrate 3 being changed. Here, the same process as the first process in the processing method of Example 1 above was carried out, with the synthetic quartz surface plate 2 rotated relative to the single crystal diamond substrate 3 at a relative speed of 1 m / s (Example 2), 2 m / s (Example 3), 3 m / s (Example 4), and 4 m / s (Example 5), and the light emission characteristics during the first process and the removal rate of the processing after the first process were confirmed.

[0083] Figure 9(a) shows the emission spectrum near the contact site during the first step, and Figure 9(b) shows the removal rate of the single-crystal diamond substrate 3 during the first step. Note that Figure 9(a) shows a spectral band (second positive band of nitrogen) generated by transition from the excited state of nitrogen molecules at wavelengths of around 300 nm to 400 nm. The vertical axis of Figure 9(a) shows the emission intensity.

[0084] 9(a), in the first step, the emission intensity of the second positive band of nitrogen increased as the relative speed of rotation of the synthetic quartz surface plate 2 with respect to the single crystal diamond substrate 3 increased. In other words, it was confirmed that the generation of excited nitrogen species tends to increase as the relative speed increases.

[0085] 9(b), in the first step, as the relative rotation speed of the synthetic quartz surface plate 2 relative to the single crystal diamond substrate 3 increased, the removal rate of the single crystal diamond substrate 3 increased. In other words, it was confirmed that the amount of wear on the processed surface of the single crystal diamond substrate 3 tends to increase as the relative speed increases.

[0086] Next, based on the processing method of Example 1 described above, processing was carried out as follows, with the load for pressing the single crystal diamond substrate 3 against the synthetic quartz surface plate 2 being varied. Here, the same process as the first process in the processing method of Example 1 above was carried out, with the single crystal diamond substrate 3 pressed against the synthetic quartz platen 2 with a load of 7 N (Example 6), 9 N (Example 7), and 14 N (Example 8), and the light emission characteristics during the first process and the removal rate of the processing after the first process were confirmed.

[0087] Figure 10(a) shows the emission spectrum near the contact site during the first step, and Figure 10(b) shows the removal rate of the single-crystal diamond substrate 3 during the first step. Note that Figure 10(a) shows a spectral band (second positive band of nitrogen) generated by transition from the excited state of nitrogen molecules at wavelengths of around 300 nm to 400 nm. The vertical axis of Figure 10(a) shows the emission intensity.

[0088] 10(a), in the first step, the intensity of the second positive band of nitrogen emission increased as the load applied to press the single-crystal diamond substrate 3 against the synthetic quartz surface plate 2 increased. In other words, it was confirmed that the generation of excited nitrogen species tended to increase as the load increased.

[0089] 10(b), in the first step, the removal rate of the single crystal diamond substrate 3 increased as the load pressing the single crystal diamond substrate 3 against the synthetic quartz surface plate 2 increased. In other words, it was confirmed that the amount of wear on the processed surface of the single crystal diamond substrate 3 tended to increase as the load increased. [Explanation of symbols]

[0090] 1 Processing equipment 2 Synthetic quartz surface plate 2a (Synthetic quartz surface plate) processed surface 3. Single crystal diamond substrate 4. Sample holder 5 Nitrogen gas supply unit 5a (Nitrogen gas supply part) tip 6 Processing table 7 Rotation Axis 100 Direction of the work surface with the highest polishing rate 110 Direction of the work surface with the lowest polishing rate

Claims

1. a first step of supplying nitrogen gas to a contact portion between a processing member made of an insulating material and a workpiece made of a single crystal diamond, while the workpiece is fixed and, with the processing member in contact with the workpiece, relatively displacing the processing member in a direction in which the polishing rate of the workpiece is higher; After the first step, a second step is provided in which nitrogen gas is supplied to a contact portion between the processed member and the workpiece, and both the processed member and the workpiece are displaced relative to each other while the processed member is in contact with the workpiece. Processing method.

2. In the first step, the uneven state of the processing surface of the processing member is transferred to the processing surface of the workpiece, In the second step, the irregularities transferred to the processed surface and the irregularities on the processed surface are reduced, and the processed surface is smoothed. The processing method according to claim 1.

3. The combination of the first process and the second process is performed multiple times. The processing method according to claim 1 or 2.

4. In the next processing of the first step on the workpiece that has been subjected to the first step and the second step, the uneven state of the processed surface that has been reduced in the previous second step is transferred to the processed surface, In the second process, which is performed following the first process, the irregularities transferred to the processed surface and the irregularities on the processed surface are reduced, and the processed surface is smoothed. The processing method according to claim 3.

5. The first step is to increase the speed at which the processing members are relatively displaced so as to promote generation of excited nitrogen species and wear of the processing surface of the workpiece. The processing method according to claim 1 or 2.

6. The first step increases the load with which the processing member contacts the workpiece so as to promote generation of excited nitrogen species and wear of the workpiece surface. The processing method according to claim 1 or 2.

7. In the second step, nitrogen gas is supplied to the contact portion of the processed member with the workpiece while the processed member is kept in contact with the workpiece. The processing method according to claim 1 or 2.

8. The second step involves bringing the processed member into contact with the workpiece again and supplying nitrogen gas to the contact area. The processing method according to claim 1 or 2.

9. The processing member is made of any one of synthetic quartz, sapphire, ceramics, glass, single crystal diamond, polycrystalline diamond, and diamond-like carbon (DLC) film. The processing method according to claim 1 or 2.

10. a processed member made of an insulating material; a holding mechanism that holds a workpiece made of single crystal diamond so that the workpiece can come into contact with the processing member; a nitrogen gas supply unit that supplies nitrogen gas to a contact portion between the processing member and the workpiece; a drive unit that relatively displaces at least one of the processing member and the workpiece while the processing member and the workpiece are in contact with each other; Controlling the nitrogen gas supply unit and the drive unit a first control for supplying nitrogen gas to a contact portion between the processing member and the workpiece, fixing the workpiece, and displacing the processing member in a predetermined direction relative to the workpiece while keeping the processing member in contact with the workpiece; and a control unit that brings the processing member into contact with the workpiece, supplies nitrogen gas to a contact portion, and performs second control to relatively displace both the processing member and the workpiece while the processing member is in contact with the workpiece. Processing equipment.

11. In the first control, the uneven state of the processing surface of the processing member is transferred to the processing surface of the workpiece, In the second control, the unevenness transferred to the processed surface and the unevenness on the processed surface are reduced, and the processed surface is smoothed. The processing device of claim 10.

12. The control unit causes the workpiece to be subjected to a plurality of processes by combining the first process and the second process. The processing device according to claim 10 or 11.

13. The processing member is made of any one of synthetic quartz, sapphire, ceramics, glass, single crystal diamond, polycrystalline diamond, and diamond-like carbon (DLC) film.

12. The processing device according to claim 10 or 11.

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