JP6692010B2 - Processing method and apparatus using radical adsorption transport - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a processing method and apparatus using radical adsorption transport, and more specifically, it is possible to perform flattening processing or arbitrary shape processing on a wide band gap semiconductor substrate such as Si, SiC, GaN, diamond, etc. TECHNICAL FIELD The present invention relates to a processing method and an apparatus for the same, which makes use of radical adsorption transport.

  Currently, Si is mainly used in semiconductor devices, but the performance is approaching the limit due to the physical properties of Si. Therefore, wide band gap semiconductors typified by silicon carbide (SiC), gallium nitride (GaN), and diamond are drawing attention. These power semiconductor device materials have physical properties such as bandgap, dielectric breakdown electric field value, thermal conductivity, and electron mobility that are several times to several tens of times higher than those of Si, so power devices are manufactured using these materials. In this case, it is possible to realize high withstand voltage, reduced power consumption, and high-speed operation. Due to these advantages, wide band gap semiconductors are expected as a material to lead the field of next-generation power semiconductor devices.

  However, planarization of a semiconductor substrate whose surface crystallinity is important in manufacturing a semiconductor power device is essential, and wide bandgap semiconductor substrates such as SiC, GaN, and diamond are hard and fragile. In processing, it is difficult to achieve highly efficient flattening without causing damage. P-CVM (Plasma Chemical Vaporization Machining) is a chemical processing method using plasma under an atmospheric pressure atmosphere, and it is possible to perform processing with high efficiency and without damaging crystals due to its high radical density. (Patent Documents 1 and 2). However, plasma processing is essentially isotropic etching, and since the entire surface direction is processed, it is not suitable for highly efficient flattening of the surface of a workpiece having irregularities.

  Therefore, we have proposed a catalyst-referenced etching (CARE) method, which has improved the disadvantage of the chemical polishing method that the surface roughness deteriorates by using a catalyst as a reference surface in the polishing platen. (Patent Document 3). In the CARE method, Ni or Pt is used for the polishing surface plate that serves as the reference surface to add a catalytic action, and the etching reaction is induced with the help of the halogen radicals generated only near the polishing surface plate. Can be selectively processed. Furthermore, since the processing proceeds only by the etching reaction, damage cannot occur in principle, and the reference surface shape can be chemically transferred. Until now, it has been confirmed that the step terrace structure of SiC or GaN has been realized by CARE processing, and the substrate surface can be flattened to the atomic level. However, since the CARE method described in Patent Document 3 uses a working fluid in which a molecule containing a halogen is dissolved, for example, hydrofluoric acid, it must be handled with extreme caution, and a waste fluid or an exhaust gas should be treated. However, there is a problem that the device configuration becomes complicated and the device configuration becomes complicated.

  In addition, essentially only water is used as the working fluid, the potential of the workpiece is controlled with respect to the working fluid, and the OH radicals produced by the dissociation of water molecules by the action of the catalyst are adsorbed on the surface of the workpiece and hydrolyzed. The Water-CARE method that can process difficult-to-process products such as solid oxides and wide bandgap semiconductor substrates such as SiC and GaN by the processing principle of removing decomposition products from the surface of the work by progressing processing It has been proposed (Patent Documents 4 and 5). However, these Water-CARE methods are excellent processing methods that do not use abrasives or abrasive grains at all and can easily treat waste liquids, but have a low processing speed, especially a low processing speed for diamond, I couldn't process it. Moreover, since the treatment is basically performed in the wet state, there are specific problems as compared with the treatment in the dry state.

Japanese Patent No. 2521127 Japanese Patent No. 2962583 JP, 2006-114632, A International Publication No. 2013/084934 JP, 2005-173216, A

  Therefore, in view of the above situation, the present invention intends to solve the problem by using radicals having a high chemical reactivity to obtain a difficult-to-processed material such as Si, SiC, GaN, or a wide bandgap semiconductor substrate such as diamond. Despite being capable of highly efficient processing, the processing is performed in a dry state, so that the apparatus configuration is simple, and its handling is easy and safe. A processing method and apparatus using radical adsorption transport are provided. There is a point.

  In order to solve the above-mentioned problems, the present invention has constituted a processing method and a processing apparatus which incorporate the following radical adsorption transport.

(1)
The surface of the movable tool having a surface with an adsorption ability and corrosion resistance to radicals rich in chemical reactivity, using a reaction gas obtained by mixing gas and a rare gas containing an element or substituent to produce at least the radical passed through a plasma generating region that caused Te, the radicals generated in the plasma generation region is adsorbed to the tool surface reactive species was granted, the said reactive species of the tool surface by movement of the tool By transporting to a workpiece surface arranged at a position different from the plasma generation region and removing a reaction product generated by a chemical reaction between atoms on the workpiece surface in contact with the tool and a reactive species, A processing method utilizing radical adsorption and transport, characterized in that only a portion of the surface of a workpiece which comes into contact with the tool surface is selectively processed using the tool surface as a processing reference surface.

(2)
The processing method using the radical adsorption transport according to (1), wherein the element that generates the radical is a halogen element of F or Cl, and the radical is an F radical or a Cl radical.

(3)
The processing method incorporating the radical adsorption transport according to (1), wherein the substituent that produces the radical is an OH group, and the radical is an OH radical.

(4)
At least the surface of the tool is formed of Ni, (1) to (3) The processing method using the radical adsorption transport according to any one of (1) to (3).

(5)
The processing method using the radical adsorption transport according to any one of (1) to (3), wherein the surface of the tool is a coating layer of alumina or yttria.

(6)
The processing method using the radical adsorption transport according to (1), wherein the tool is a rotary surface plate tool, and the surface of the workpiece is flattened using the surface of the rotary surface plate tool as a processing reference plane.

(7)
The tool is a spherical rotary tool having a rotary shaft, plasma is generated in the vicinity of the outer peripheral portion of the spherical rotary tool, and radicals are adsorbed to the outer peripheral portion of the spherical rotary tool to generate plasma in the spherical rotary tool. Radical adsorption transport according to (1), in which an outer peripheral portion different from the region is rotated while being brought into contact with the surface of the workpiece at a predetermined pressure and the contact portion is numerically controlled and scanned on the surface of the workpiece to have an arbitrary shape. Processing method with the aid of.

(8)
A rotary surface plate tool having a surface having corrosion resistance and adsorption ability for radicals rich in chemical reactivity,
An electrode head arranged with a predetermined gap provided on the surface of the rotary platen tool,
Gas supply means for supplying to the electrode head a reaction gas in which a gas containing at least the element generating the radical or a substituent and a rare gas are mixed,
A high-frequency power source that applies a high-frequency electric field to the electrode head to generate plasma in the gap,
A work piece is held in front of the rotating surface plate tool surface to which the radicals generated in the plasma generation region are adsorbed and reactive species are given, and the work piece is held on the rotating surface plate tool surface at a predetermined pressure. A work holder to contact
A processing apparatus assisting radical adsorption and transport, characterized in that the surface of a workpiece is flattened by using the surface of the rotary platen as a processing reference surface.

(9)
With a rotary shaft, a spherical rotary tool having corrosion resistance and adsorption ability for radicals rich in chemical reactivity at least on the outer peripheral surface,
An electrode arranged with a predetermined gap provided on the outer peripheral portion of the spherical rotary tool,
Gas supply means for supplying to the electrode a reaction gas obtained by mixing a gas containing at least the element generating the radical or a substituent and a rare gas,
A high-frequency power source that applies a high-frequency electric field to the electrodes to generate plasma in the gap,
The spherical rotation in a state in which the outer peripheral portion of the spherical rotary tool to which the radicals generated in the plasma generation area are adsorbed and the reactive species are applied is different from the plasma generation area in contact with the workpiece surface at a predetermined pressure. Scanning means for relatively numerically controlling the tool and the workpiece,
Radical adsorption transport, characterized in that the spherical rotary tool and the contact part of the workpiece are numerically controlled and scanned on the surface of the workpiece to process the spherical rotary tool surface into an arbitrary shape as a processing reference plane. Processing equipment incorporated.

(10)
The element that generates a radical is a halogen element F or Cl, the radical is F radicals or Cl radical (8) or (9) machining apparatus the aid of radical adsorption transport according.

(11)
The processing device incorporating the radical adsorption transport according to (8) or (9), wherein the radical-generating substituent is an OH group, and the radical is an OH radical.

(12)
At least the surface of the rotary platen tool or the spherical rotary tool is formed of Ni. (8) or (9).

(13)
The processing apparatus using the radical adsorption transport according to (8) or (9), wherein the surface of the rotary platen tool or the spherical rotary tool is a coating layer of alumina or yttria.

  According to the processing method and apparatus using the radical adsorption transport of the present invention as described above, dry etching is realized with the tool surface for adsorbing radicals as the processing reference plane. There is no other dry etching technique having such a processing reference plane. According to the present invention, it is expected that the single crystal material can be flattened strain-freely with high efficiency, and next-generation semiconductor substrates such as wide bandgap semiconductor substrates made of SiC, GaN, diamond or the like can be improved in quality and reduced in price. Further, in the present invention, even a substrate having a non-uniform crystallinity due to crystal growth, a polycrystalline substrate, or the like, which has been difficult to perform uniform processing by the conventional technique, can be processed uniformly by the effect of the processing reference plane. It can be realized. Further, in the present invention, the plasma does not come into direct contact with the surface of the workpiece, so it is considered possible to process even a material having a low heat resistant temperature.

It is a conceptual diagram of the processing apparatus which assists the radical adsorption transport of this invention. It is a simplified perspective view of the processing apparatus which also used the radical adsorption transport of this invention. It is a simplified perspective view of the planarization processing apparatus of 1st Embodiment of this invention. Similarly, a part of the flattening apparatus of the first embodiment is shown, (a) is a perspective view of an electrode head, and (b) is a partial cross-sectional view showing the relationship between the electrode head and a workpiece. The concept of the numerical control processing apparatus of 2nd Embodiment of this invention is shown, (a) is a front view, (b) is a side view. As the processing experiment 1, the result of the flattening processing experiment of the Si substrate is shown, and it is a white interferometer image showing the surface state under the condition that plasma is not generated at each place and every time. As a processing experiment 1, a result of a flattening processing experiment of a Si substrate with F radicals is shown, and a white interferometer image showing a surface state under a condition where plasma is generated at each place and each time. As the processing experiment 2, the result of the flattening processing experiment of the SiC substrate is shown, and it is a white interferometer image showing the surface condition before and after the processing. It is a conceptual diagram of a processing apparatus when using a mixed gas of He and water vapor as a reaction gas. As a processing experiment 3, a result of a flattening processing experiment of a Si substrate is shown, and is a white interferometer image showing a surface state under a condition that plasma is not generated at each place and each time. As a processing experiment 3, a result of a flattening processing experiment of an Si substrate with OH radicals is shown, and is a white interferometer image showing a surface state under a condition where plasma is generated at each place and each time. As the processing experiment 4, the result of the flattening processing experiment of the Si substrate using the rotary platen tool on which the alumina coating layer is formed is shown, and is a white interferometer image of the surface state under the condition that plasma is not generated. As the processing experiment 4, the results of the flattening processing experiment by the F radical of the Si substrate using the rotary platen tool on which the alumina coating layer is formed are shown, and the surface condition under the condition that the plasma is generated is shown at each place and every hour. It is a white interferometer image.

  Next, the present invention will be described in more detail based on the embodiments shown in the accompanying drawings. 1 and 2 are conceptual views of a processing apparatus that employs radical adsorption and transport according to the present invention, where W is a workpiece, 1 is a rotary platen tool, 2 is an electrode head, 3 is gas supply means, and 4 is A high frequency power source and 5 respectively indicate work holders.

  The processing principle of the present invention is as follows. First, at least in the vicinity of a movable tool (rotary platen tool 1) having a surface having corrosion resistance and adsorption ability to free radicals (hereinafter, simply referred to as “radicals”) rich in chemical reactivity, A radical R is generated in the plasma generation region P by generating a plasma of a reaction gas in which a gas containing a generated element or a substituent and a rare gas are mixed. When the surface of the movable tool passes through the plasma generation region P, the radicals R are highly coordinated with atoms on the surface of the tool or are excessively adsorbed to become reaction active species, and the workpiece is processed by the movement of the tool. It is transported to the surface of the object W. The reactive species that have been transported to the surface of the workpiece W that has come into contact with the tool move to the surface atom side of the workpiece W, weaken the back bonds of the surface atoms and bond to form a reaction product. Become. This reaction product is removed from the surface of the workpiece W, so that the surface atoms of the workpiece W are removed, that is, the surface atoms of the workpiece W are etched.

Here, as the element that generates the radical, a halogen element of F or Cl can be cited, and specifically, the halogen element-containing gas includes SF ₆ , CF ₄ , NF _{3 and the} like as the element that contains the F element. there are _{Cl 2,} CCl _4, PCl 4 such as those containing the element Cl. Here, it is also possible to use O ₂ gas as the gas that generates the radicals. Further, as the substituent for generating the radical, it includes OH groups, typically as a gas containing OH groups is H _{2 O.} The substituent represents a partial structure of the molecule and corresponds to the free radical. The rare gas may be helium gas or argon gas. In addition to these radical-producing gas and rare gas, a trace amount of a third gas may be added to the reaction gas. Here, the pressure P _G of the reaction gas is basically atmospheric pressure, but it may be in a reduced pressure state or a vacuum state. In this case, the reactive active species formed on the tool surface by adsorption of the radical R are Rapid release from the tool surface must be avoided.

  The surface of the rotary platen tool 1 serves as a processing reference plane. The material that can be used for the surface of the rotary platen tool 1 is required to have corrosion resistance and adsorption ability for radicals, various metal materials such as Ni can be used, and the surface of the substrate can be used. A coating layer may be formed by spraying alumina, yttria, or the like on. In the present embodiment, the rotary platen tool 1 has a surface on which a Ni layer 6 having a thickness of 20 μm is formed by electroless Ni plating, or an alumina coating layer formed by thermal spraying. Here, the Ni layer 6 may be formed by electrolytic plating or vacuum vapor deposition in addition to electroless plating. Further, the tool 1 itself may be made of bulk Ni.

  The electrode head 2 is arranged with a predetermined gap G provided on the surface of the rotary platen tool 1, and at least radicals are generated from the gas supply means 3 in the gap between the electrode head 2 and the surface of the rotary platen tool 1. A reaction gas obtained by mixing a rare gas with a gas containing an element or a substituent to be supplied is supplied. The electrode head 2 has a gas flow path forming a gas supply means 3 at the center, is connected to a gas cylinder (not shown) by a gas supply pipe, and is configured to inject a reaction gas toward the tip.

  Then, a high-frequency electric field is applied to the electrode head 2 from a high-frequency power source 4 to generate atmospheric pressure plasma composed of the reaction gas in the gap G. The rotary surface plate tool 1, the electrode head 2 and the like may be housed in a chamber to generate plasma in a reduced pressure atmosphere. Normally, the high frequency power source 4 uses an RF power source with a frequency of 13.56 MHz, but a frequency up to about 200 MHz can be used.

Here, when the surface of the rotary platen tool 1 passes through the plasma generation region P, the radical R generated in the plasma generation region P is highly coordinated with Ni atoms of the Ni layer 6 on the surface, Alternatively, it is excessively adsorbed to become a reactive species and is transported forward in the rotational direction with the rotation thereof. The workpiece W held by the work holder 5 is brought into contact with the surface of the rotary platen tool 1 in front of the plasma generation region in the rotation direction at a predetermined pressure. This is referred to as a contact pressure P _L , which is distinguished from the processing atmosphere pressure P _G. As a result, the reactive active species derived from the radicals R adsorbed to the Ni layer 6 in the plasma generation region and transported by the rotation of the rotary platen tool 1 are the surfaces of the workpiece W and the rotary platen tool 1. The back bond of the constituent atoms of the workpiece W is weakened and bonded at a contact portion with the workpiece W to form a reaction product, and the reaction product is volatilized or removed by an appropriate method to form a workpiece. The surface of the object W is processed. Since the workpiece W is selectively machined from the convex portion in contact with the surface of the rotary platen tool 1, it is planarized with the Ni layer 6 as a machining reference surface. In this case, if the work holder 5 is rotated about an axis in the same direction as the rotation axis of the rotary platen tool 1, the machining is averaged and the flatness is further increased.

  As described above, the main components of the present invention are plasma generation means (electrode head 2, gas supply means 3 and high frequency power source 4) for radical generation, and a tool for adsorbing and transporting radicals on the surface (rotary platen tool). 1) and a work holder 5 that holds the workpiece W and keeps contact with the tool. According to the present invention, it is possible to selectively dry-etch only a portion in contact with a radical adsorption tool, which is extremely innovative. F radicals, Cl radicals, O radicals, OH radicals, etc., which are the main reactive species in atmospheric pressure plasma etching, are generated in the plasma generation region and adsorbed on the surface of the tool (rotary surface plate tool). The surface on which these radicals are adsorbed is in a highly coordinated state with rich reactivity. Then, the reaction active species derived from the radicals adsorbed by the movement of the tool are transported to the surface of the workpiece W, and the surface atoms of the workpiece W in contact with the tool and the reactive species on the tool surface react by a chemical reaction. By becoming a product and being removed, the surface of the workpiece is etched.

The flattening processing apparatus of the first embodiment of the present invention is shown in FIGS. 3 and 4. The flattening apparatus of the present embodiment is provided with an opening 7 in the center, and has a horizontal rotary platen tool 1 having a surface having corrosion resistance and adsorption ability for radicals, and a surface of the rotary platen tool 1. An electrode head 2 arranged with a predetermined gap therebetween, gas supply means 3 for supplying to the electrode head 2 a reaction gas obtained by mixing a rare gas with a gas containing at least a radical-producing element or a substituent, A high-frequency power source 4 for applying a high-frequency electric field to the electrode head 2 to generate plasma in the gap, and a surface of the rotary surface plate tool 1 to which radicals generated in the plasma generation region P are adsorbed and reactive reactive species are applied. holding the workpiece W forward in the rotational direction, the work holder 5 is brought into contact with the workpiece W on the rotating surface plate surface of the tool 1 at a predetermined pressure (contact pressure P _L), comprising a workpiece The surface of those to be processed flattened. Here, the pressure P _G of the processing atmosphere is basically atmospheric pressure, but may be a reduced pressure atmosphere.

  A Ni layer 6 is formed on the surface of the rotary platen tool 1 by electroless Ni plating. Here, the rotary platen tool 1 is grounded, and the Ni layer 6 serving as a machining reference surface has a ground potential. The base of the electrode head 2 is supported by a vertical shaft in the center of the opening 7 of the rotary platen tool 1, and the head can be horizontally swung. As shown in FIGS. 4 (a) and 4 (b), the electrode head 2 holds the base of a horizontal arm portion 8 with a rotary joint 9, and the head portion 10 is provided on the surface of the rotary platen tool 1 in a predetermined manner. It is arranged with a gap. Further, in the electrode head 2, a gas flow path 11 is formed continuously from the rotary joint 9 to the arm portion 8 and the head portion 10, and constitutes a part of the gas supply means 3. Since the head portion 10 of the electrode head 2 is exposed to plasma and is worn away, it is preferable to have a replaceable structure. The electrode head 2 can adjust the distance from the workpiece W held by the work holder 5 by changing the rotation angle around the rotary joint 9.

  The rotary drive mechanism of the rotary platen tool 1 and the drive mechanism of the work holder 5 have the same structure as a conventional polishing apparatus, and the conventional polishing apparatus includes the electrode head 2, the gas supply unit 3, and the high frequency power source 4. The flattening processing apparatus of the present invention can be constructed only by adding the flattening processing apparatus. Moreover, since the present invention is dry etching, a structure around water is unnecessary, and the device configuration can be simplified.

FIG. 5 shows a numerically controlled machining apparatus according to a second embodiment of the present invention. The numerical control machining apparatus of the present embodiment includes a rotary shaft 20 and a spherical rotary tool 21 having corrosion resistance and adsorption ability for radicals on at least the outer peripheral surface, and an outer peripheral portion 22 of the spherical rotary tool 21. On the other hand, an electrode 23 provided with a predetermined gap G, and a gas supply means (not shown) for supplying to the electrode 23 a reaction gas obtained by mixing a gas containing at least a radical-producing element or a substituent and a rare gas. A high-frequency power source 24 for generating a plasma in the gap G by applying a high-frequency electric field to the electrode 23, and a plasma for the spherical rotary tool 21 to which radicals generated in the plasma generation region P are adsorbed and reactive reactive species are added. the outer peripheral portion 22 which is different from the generation region P, being in contact with a predetermined pressure to the surface of the workpiece W (contact pressure P _L), and the spherical rotary tool 21 Scanning means (not shown) for relatively numerically controlling the workpiece W to scan the contact portion C between the spherical rotary tool 21 and the workpiece W on the surface of the workpiece W by the numerical control. Then, it is processed into an arbitrary shape. In this case, the reactive species derived from the radicals adsorbed on the outer peripheral portion 22 of the spherical rotary tool 21 are transported to the contact portion C with the workpiece W as the spherical rotary tool 21 rotates. In this embodiment as well, the pressure P _{G of the} processing atmosphere is basically atmospheric pressure, but it may be a reduced pressure atmosphere.

  The spherical rotary tool 21 is not limited to a literal spherical shape, and may be a disk-shaped or tire-shaped outer peripheral portion 22 having a circular arc surface. Then, in order to process the surface of the workpiece W into an arbitrary shape, a profile of a unit processing mark formed at the contact portion C by the spherical rotary tool 21 is acquired, and local processing on the surface of the workpiece W is performed. The staying time of the contact portion C is defined based on the amount data. Actually, since the scanning is repeated, the dwell time is controlled by changing the scanning speed. The numerical control scanning is performed by driving either the spherical rotary tool 21 or the workpiece W.

<Processing experiment 1 to verify the processing principle>
Next, an experiment for demonstrating the processing principle of the present invention was conducted using the flattening processing device. In other words, the basic experiment conducted to confirm whether the radicals generated by plasma are adsorbed on the rotating platen and the reactive species given to the surface of the rotating platen are supplied to the contact area with the workpiece. The result of is shown.

As a radical adsorption tool, a rotary platen tool with electroless Ni plating applied to a thickness of 20 μm was used, and a reaction gas of He: SF ₆ = 99: 1 (pressure P _G : large) at a position approximately 15 mm upstream of the sample (silicon substrate). The change of the surface of the sample was compared when the plasma of atmospheric pressure was generated and when it was not generated. As the sample, a 10 mm square substrate of Si having a poor surface roughness was used. The sample is not rotated but only the rotary platen tool is rotated, the rotation speed is 10 rpm, and the contact pressure P _L for pressing the sample against the rotary platen tool is 3 kPa. Table 1 shows the experimental conditions for generating plasma. The surface roughness of the sample surface was evaluated every hour. As a method of evaluating the surface roughness, four observation points were measured in a range of 64 × 48 (μm ² ) with a white light interferometer (NewView 200 manufactured by Zygo).

  First, FIG. 6 shows the result of processing in a state where plasma is not generated (no voltage is applied, no reaction gas is supplied). The sample was processed at a rotation speed of 10 rpm and a pressure of 3 kPa, and the surface roughness was measured every hour. Figure 6 shows the white interferometer (NewView 200 manufactured by Zygo Co., Ltd.) from the center of the substrate, the upper part, the right part, and the left part, which are marked with ○ in the left column in Fig. 6, from before processing to after 3 hours processing. Show. The upper portion of the Si substrate is a portion near the electrode head 2 and the same applies hereinafter. Since no improvement in surface roughness was observed at any of the observation points, it was confirmed that there was no mechanical working under the processing conditions of a rotation speed of 10 rpm and a contact pressure of 3 kPa.

  Next, FIG. 7 shows the result of processing in the state where plasma is generated (voltage applied, reaction gas supplied). While plasma was generated under the conditions shown in Table 1, the sample was processed at a rotation speed of 10 rpm and a contact pressure of 3 kPa, and the surface roughness was measured every hour. Figure 7 shows the white interferometer (NewView 200 by Zygo) from before processing to after processing for 3 hours at the four points of the center part, upper part, right part and left part of the substrate, which are marked with a circle in the left column of Fig. 7. Show. Due to the action of the reactive radicals derived from the F radical, the surface roughness (rms) at any of the observation points increased from more than 400 nm before processing to 10 nm or less after processing for 3 hours, showing a significant improvement. It was

  Since the surface roughness was not improved by the processing without plasma generation, it is considered that the mechanical processing does not work, and the radicals generated in the plasma generation area are adsorbed on the surface of the polishing surface plate. It was confirmed that was supplied to the sample surface as the polishing surface plate rotated. In plasma etching in which the sample surface is directly exposed to plasma, the removal rate is isotropic, so flattening is not possible, but by generating plasma between the rotary surface plate tool and the electrodes, F radicals are adsorbed to the rotary surface plate tool. Then, the reaction-active species derived from the F radicals were supplied to the sample surface as the rotary platen tool was rotated, whereby the sample surface was flattened. In this experiment, it was clarified that reactive active species derived from F radicals were supplied to the surface of the sample, thereby planarizing the Si substrate.

<Processing experiment 2 to verify the processing principle>
Next, FIG. 8 shows the result of a similar experiment performed using the flattening apparatus using a SiC substrate as a workpiece. The plasma generation conditions are the same as those shown in Table 1, but the contact pressure P _L of the SiC substrate in this case is 5 kPa. By the flattening process for 3 hours, the surface roughness (rms) of the SiC substrate was flattened from more than 100 nm before the process to 10 nm or less. It was confirmed that the SiC substrate is planarized similarly to the Si substrate by the action of the F radical.

<Processing experiment 3 to verify the processing principle>
Next, a reaction gas of He and H ₂ O (water vapor) (pressure P _G : atmospheric pressure) was used as a reaction gas, and the Si substrate (area: 0.59 cm) was used as a workpiece using the flattening processing apparatus. The surface of ² ) was processed. Table 2 shows plasma generation conditions and processing conditions. Also in this case, a rotary platen tool having electroless Ni plating of 20 μm thick was used. The contact pressure P _L of the Si substrate is 3.4 kPa. As shown in FIG. 9, the reaction gas containing water vapor was used by putting water in a closed container, ejecting He gas in the water, and collecting the reaction gas of He and water vapor in the gas phase. The gap G between the rotary platen tool 1 and the electrode head 2 was 200 μm, and the distance L from the electrode head 2 to the downstream Si substrate was 15 mm.

  First, FIG. 10 shows a result of processing in a state where plasma is not generated (no voltage applied, no reaction gas is supplied). In FIG. 10, the upper part is the upper part of the Si substrate, and the lower part is the image of the white interferometer (NewView 200 manufactured by Zygo Co.) in the central part of the Si substrate, respectively, from left to right, after processing for 30 minutes and after processing for 1 hour. It shows after processing. Also in this case, it can be seen that there is almost no change in the surface of the Si substrate even after 1 hour.

  Next, FIG. 11 shows the result of processing in a state where plasma is generated (voltage applied, reaction gas supplied). In FIG. 11, the upper part is the upper part of the Si substrate and the lower part is the image of the white interferometer (NewView 200 manufactured by Zygo Co.) in the center part of the Si substrate, respectively, from left to right, after processing for 30 minutes and after processing for 1 hour. It shows after processing, after processing for 1.5 hours, after processing for 2 hours, and after processing for 3 hours. At the upper part of the Si substrate, the surface roughness (rms) before processing was 167 nm before processing, but it was found to be improved to 22 nm after processing for 1 hour and to 16 nm after processing for 3 hours. .. On the other hand, in the central portion of the Si substrate, the surface roughness (rms) before processing was 184 nm before processing, but improved to 48 nm after processing for 1 hour and to 16 nm after processing for 3 hours. I understand. It is considered that the generation of steam plasma generated OH radicals, which contributed to the processing of the Si substrate surface.

<Processing experiment 4 to verify the processing principle>
Finally, using the flattening apparatus, a rotary platen tool having a conductive substrate surface coated with alumina (Al ₂ O ₃ ) was used, and a Si substrate (area: 0.78 cm ² ) was used as a workpiece. The surface was processed. Table 3 shows plasma generation conditions and processing conditions. In this case, the conditions are substantially the same as the conditions in Table 1, but the contact pressure P _L of the Si substrate with respect to the rotary platen tool is increased to 5.1 kPa. The gap G between the rotary surface plate tool and the electrode head was 600 μm, and the distance L from the electrode head to the downstream Si substrate was 15 mm.

First, FIG. 12 shows a result of processing in a state where plasma is not generated (no voltage applied, no reaction gas is supplied). In this case, it was found that even if the contact pressure P _L was 1 kPa, a mechanical processing line was generated and flattening processing could not be performed at all. It can be inferred that the reason why the processing line is generated is that the fine Si scraps generated by the chipping of the edge of the Si substrate are sandwiched between the rotary surface plate tool and the Si substrate and damage the surface of the Si substrate.

  Next, FIG. 13 shows a result of processing in a state where plasma is generated (voltage is applied, reaction gas is supplied). In FIG. 13, the upper part is the upper part of the Si substrate and the lower part is the image of the white interferometer (NewView 200 manufactured by Zygo) of the lower part of the Si substrate, respectively, from left to right, before processing, after processing for 30 minutes, and after processing for 1 hour. After that, processing after 1.5 hours is shown. In the upper part of the Si substrate, the surface roughness (rms) before processing was 547 nm before processing, but it was significantly improved to 72 nm after processing for 30 minutes, and 21 nm after processing for 1 hour. It can be seen that it improved to 24 nm after processing for 5 hours. On the other hand, in the lower part of the Si substrate, the surface roughness (rms) before processing was 592 nm before processing, but it did not improve much to 470 nm after processing for 30 minutes, but after processing for 1 hour. It can be seen that after processing at 80 nm for 1.5 hours, it has improved to 40 nm.

This processing experiment shows that the Si substrate could be planarized by using the alumina tool. Alumina tools have excellent surface stability and little deterioration over time, and are therefore advantageous in practical use. Even if the contact pressure P _L of the Si substrate with respect to the rotary surface plate tool is set to 5.1 kPa, the mechanical processing line does not occur because the fine Si scraps attached to the rotary surface plate tool cause It can be inferred that it was removed by plasma etching when passing.

  In the above examples, the flattening process and the application example to the numerical control process by the spherical rotary tool are shown, but in addition, it is considered that various applications such as the groove process by the wire traveling tool and the shape of the radical adsorption tool are possible. Be done. Also, diamond tools and jewels can be machined into a flat surface or an acute angle.

1 rotary surface plate tool,
2 electrode head,
3 gas supply means,
4 high frequency power supply,
5 work holders,
6 Ni layer,
7 openings,
8 arm parts,
9 rotary joint,
10 head part,
11 gas flow path,
20 rotation axis,
21 Spherical rotating tool,
22 outer periphery,
23 electrodes,
24 high frequency power supply,
W Workpiece,
G gap,
P plasma generation area,
R radical,
C contact part,

Claims (13)

The surface of the movable tool having a surface with an adsorption ability and corrosion resistance to radicals rich in chemical reactivity, using a reaction gas obtained by mixing gas and a rare gas containing an element or substituent to produce at least the radical passed through a plasma generating region that caused Te, the radicals generated in the plasma generation region is adsorbed to the tool surface reactive species was granted, the said reactive species of the tool surface by movement of the tool By transporting to a workpiece surface arranged at a position different from the plasma generation region and removing a reaction product generated by a chemical reaction between atoms on the workpiece surface in contact with the tool and a reactive species, A processing method utilizing radical adsorption and transport, characterized in that only a portion of the surface of a workpiece which comes into contact with the tool surface is selectively processed using the tool surface as a processing reference surface.   The processing method using the radical adsorption transport according to claim 1, wherein the element generating the radical is a halogen element of F or Cl, and the radical is an F radical or a Cl radical.   The processing method using radical adsorption and transport according to claim 1, wherein the substituent that generates the radical is an OH group, and the radical is an OH radical.   The processing method using the radical adsorption transport according to any one of claims 1 to 3, wherein at least a surface of the tool is made of Ni.   The processing method using the radical adsorption transport according to any one of claims 1 to 3, wherein the surface of the tool is a coating layer of alumina or yttria.   The method according to claim 1, wherein the tool is a rotary platen tool, and the surface of the workpiece is flattened using the rotary platen tool surface as a machining reference surface.   The tool is a spherical rotary tool having a rotary shaft, plasma is generated in the vicinity of the outer peripheral portion of the spherical rotary tool, and radicals are adsorbed to the outer peripheral portion of the spherical rotary tool to generate plasma in the spherical rotary tool. The radical adsorption transport according to claim 1, wherein an outer peripheral portion different from the area is rotated while being brought into contact with the surface of the workpiece at a predetermined pressure, and the contact portion is numerically controlled and scanned on the surface of the workpiece to be processed into an arbitrary shape. Processing method with the aid of. A rotary surface plate tool having a surface having corrosion resistance and adsorption ability for radicals rich in chemical reactivity,
An electrode head arranged with a predetermined gap provided on the surface of the rotary platen tool,
Gas supply means for supplying to the electrode head a reaction gas in which a gas containing at least the element generating the radical or a substituent and a rare gas are mixed,
A high-frequency power source that applies a high-frequency electric field to the electrode head to generate plasma in the gap,
A work piece is held in front of the rotating surface plate tool surface to which the radicals generated in the plasma generation region are adsorbed and reactive species are given, and the work piece is held on the rotating surface plate tool surface at a predetermined pressure. A work holder to contact
A processing apparatus assisting radical adsorption and transport, characterized in that the surface of a workpiece is flattened by using the surface of the rotary platen as a processing reference surface. With a rotary shaft, a spherical rotary tool having corrosion resistance and adsorption ability for radicals rich in chemical reactivity at least on the outer peripheral surface,
An electrode arranged with a predetermined gap provided on the outer peripheral portion of the spherical rotary tool,
Gas supply means for supplying to the electrode a reaction gas obtained by mixing a gas containing at least the element generating the radical or a substituent and a rare gas,
A high-frequency power source that applies a high-frequency electric field to the electrodes to generate plasma in the gap,
The spherical rotation in a state in which the outer peripheral portion of the spherical rotary tool to which the radicals generated in the plasma generation area are adsorbed and the reactive species are applied is different from the plasma generation area in contact with the workpiece surface at a predetermined pressure. Scanning means for relatively numerically controlling the tool and the workpiece,
Radical adsorption transport, characterized in that the spherical rotary tool and the contact part of the workpiece are numerically controlled and scanned on the surface of the workpiece to process the spherical rotary tool surface into an arbitrary shape as a processing reference plane. Processing equipment incorporated. The processing device using the radical adsorption transport according to claim 8 or 9, wherein the element generating the radical is a halogen element of F or Cl, and the radical is an F radical or a Cl radical.   The processing device using the radical adsorption transport according to claim 8 or 9, wherein the substituent that generates the radical is an OH group, and the radical is an OH radical.   10. The processing apparatus assisting radical adsorption and transport according to claim 8 or 9, wherein at least the surface of the rotary platen tool or the spherical rotary tool is made of Ni.   The processing apparatus using the radical adsorption transport according to claim 8 or 9, wherein the surface of the rotary platen tool or the spherical rotary tool is a coating layer of alumina or yttria.

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