JP5182852B2 - Silicon carbide abrasive and silicon carbide polishing method using the same - Google Patents

Description

  The present invention relates to a laminate comprising at least a carbon layer on a substrate for polishing the surface of a silicon carbide (SiC) single crystal. In particular, the carbon layer provided on the substrate has a high hardness and smoothness. The present invention relates to a laminate that is effective as an abrasive because it has a smooth surface.

  In recent years, high specularity and flatness of SiC single crystals are required in various fields. For example, when SiC is used for power devices and semiconductor devices, a SiC single crystal with a surface roughness of nanometers or less and a much higher specularity and flatness than conventional ones is required. I came. In order to satisfy these requirements, it is essential to develop a more advanced polishing method for the SiC single crystal surface.

  Conventionally, methods of machining and chemical mechanical polishing (CMP) have been mainly used for polishing a SiC single crystal surface. As a method by machining, for example, a method is generally used in which a roughened SiC single crystal surface is roughly ground by a physical means such as a grinder and then polished using diamond abrasive grains.

  And in order to obtain the final flatness, chemical mechanical polishing (CMP), which combines the mechanical removal action at nanometer scale by ultrafine abrasive grains and the chemical removal action by machining fluid with etching effect Is currently required.

  However, since CMP uses chemicals, the problem is that the environmental impact of waste liquid is high. Therefore, it is desired to develop a polishing method with a smaller environmental load in place of this CMP.

On the other hand, the present inventors attach diamond fine particles to a substrate such as glass, silicon, iron, titanium, copper, and plastic by ultrasonic treatment, and apply a low-temperature surface wave plasma CVD method thereto to obtain a particle size of 2 It has been found that a carbon film having a thickness of 2 μm or more in which carbon particles of ˜30 nm are densely deposited can be formed, and that the hardness of the carbon film is 20 GPa or more (see Patent Document 1).
International Publication No. 2005/103326 Pamphlet

  The present invention has been made in view of the circumstances as described above, and its purpose is to use a high adhesion, hardness, and surface flatness to the base material of the carbon film, and to have a high environmental impact. It is an object of the present invention to provide a laminate capable of polishing and grinding a SiC single crystal surface having high hardness at a high speed and simply with high flatness and accuracy without using chemicals.

  As a result of further earnest research on the laminate composed of the above-described substrate and the carbon layer provided on the substrate, the present inventors have found that in addition to the diamond particles and carbon particles constituting the carbon layer, By using a generation / growth inhibitor that suppresses the generation of impurities that inhibit growth and / or suppresses the growth of the carbon particles, a carbon layer having high adhesion to the substrate, hardness, and surface flatness As a result, it has been found that a laminated body capable of polishing and grinding a SiC single crystal surface having high hardness at high speed and simply with high flatness and accuracy can be provided.

The present invention has been completed based on these findings, and is as follows.
(1) a laminate comprising a carbon layer provided on the substrate and the base material, a polishing material for polishing a silicon carbide single crystal surface,
The carbon layer includes diamond fine particles which are provided on the base material and are pulverized by impact, amorphous SiO ₂ present so as to fill gaps between the diamond fine particles, carbon particles, and particles of the carbon particles. Consists of amorphous Si and / or SiO ₂ that suppresses the generation of impurities that are deposited and coated in the voids and / or voids between the carbon particles and inhibits the growth of carbon particles and / or suppresses the growth of carbon particles Has been
The proportion of amorphous SiO ₂ in the 10-20 nm region of the lowermost layer of the carbon layer is 50 atomic% or more, and the amount of this amorphous SiO ₂ is changed from the lower layer on the substrate side of the carbon layer to the upper layer. At least 80 nm or more of carbon particles from the substrate of the carbon layer, and
An abrasive for a silicon carbide single crystal surface , wherein the carbon layer has a surface roughness Ra of 4 nm to 6 nm .
(2) the substrate is silicon, quartz, glass, stainless steel, or abrasive silicon carbide single crystal surface according to, characterized in Rukoto such from either (1) the aluminum.
(3) The polishing material for a silicon carbide single crystal surface according to (1) or (2), wherein an adhesion reinforcing layer is provided between the substrate and the carbon layer.

  The laminate of the present invention has high adhesion to the substrate, hardness, and surface flatness of the carbon layer. Therefore, by using the laminate of the present invention, it is possible to polish and grind a hard material surface such as a SiC single crystal surface at high speed and simply with high flatness and accuracy without using chemicals with high environmental impact. It is possible to provide a possible laminate.

1 to 4 are sectional views showing an outline of the vicinity of the substrate of the laminate of the present invention.
The laminate of the present invention includes a base material and a carbon layer provided on the base material, and the carbon layer is provided on the base material and is subjected to impact and pulverized diamond fine particles, and carbon particles A generation / growth suppression material that suppresses the generation of impurities that inhibit the growth of carbon and / or suppresses the growth of carbon particles, and carbon particles, The laminate is characterized by decreasing from the lower layer on the substrate side toward the upper layer, and has a laminated structure as shown in FIG. In the present invention, “impurities that inhibit the growth of carbon particles” refers to amorphous carbon, graphite, and the like that are generated along with the formation of carbon particles at the grain boundaries of carbon particles and / or voids between carbon particles. .
Specifically, the carbon layer is provided with diamond fine particles provided on the base material and subjected to impact and pulverization, a SiO ₂ material or an Al ₂ O ₃ material, and carbon particles, and the SiO ₂ material or The amount of the Al ₂ O ₃ material (amount per unit volume) decreases from the lower layer on the substrate side toward the upper layer. The laminate is characterized in that the carbon particles are 70 atomic % or more at least 80 nm or more from the base material of the carbon layer, and has a laminated structure as shown in FIG.

Another laminate of the present invention includes a base material, an adhesion reinforcing layer provided on the base material, and a carbon layer provided on the adhesion reinforcing layer, and the carbon layer includes the adhesion reinforcing material. A diamond fine particle provided in a layer and impacted and crushed, a generation / growth suppression material that suppresses the generation of impurities that inhibit the growth of carbon particles and / or suppresses the growth of carbon particles, and carbon particles, The amount of the production / growth inhibitor (amount per unit volume) decreases from the lower layer to the upper layer of the adhesion strengthening layer, and has a laminated structure as shown in FIG. have.
Specifically, the carbon layer includes diamond fine particles provided on the adhesion strengthening layer and pulverized by impact, SiO ₂ material or Al ₂ O ₃ material, and carbon particles, and the SiO ₂ material or The amount of Al ₂ O ₃ material (amount per unit volume) decreases from the lower layer on the adhesion reinforcing layer side toward the upper layer, and the carbon is at least 80 nm or more from the adhesion reinforcing layer of the carbon layer. It is a laminated body characterized in that particles are 70 atomic % or more, and has a laminated structure as shown in FIG.

  In the present invention, prior to the plasma CVD treatment for depositing the carbon layer on the substrate, the nanocrystal diamond particles, cluster diamond particles or graphite cluster diamond particles are applied to the substrate or the substrate provided with the adhesion reinforcing layer. The diamond fine particles are pulverized by applying an impact with ultrasonic waves, and a part of the pulverized diamond fine particles are bitten into the surface of the base material, and a part thereof is adhered to the surface of the base material. Diamond fine particles that bite into the substrate surface function as anchor diamond fine particles that enhance the adhesion of the carbon layer to the substrate and / or growth carbon particles that contribute to the growth of the carbon layer. Further, the diamond fine particles adhering to the substrate surface have a function as growth contributing carbon particles contributing to the growth of the carbon layer.

Nanocrystalline diamond particles are usually diamond produced by explosive synthesis or by grinding diamond synthesized at high temperature and pressure.
Nanocrystal diamond is a colloidal solution in which nanocrystal diamond by explosion synthesis is dispersed in a solvent from Nanocarbon Research Laboratories, etc., or nanocrystal diamond powder produced by pulverization, or in which it is dispersed in a solvent. Already sold by Tomei Diamond Co., Ltd. The nanocrystal diamond particles used in the present invention have an average particle size of 4 to 100 nm, preferably 4 to 10 nm. The nanocrystal diamond particles are described in detail in the literature, for example, in “Hiraki Makita, New Diamond Vol.12 No. 3, pp. 8-13 (1996)”.

In order to provide nanocrystal diamond particles on the substrate or the adhesion reinforcing layer, first, the particles are dispersed in water or ethanol. At this time, in order to improve dispersibility, a surfactant (for example, sodium lauryl sulfate ester, sodium oleate, etc.) is added to prepare a dispersion.
The particle size distribution of the nanocrystal diamond particles in this dispersion was measured using a dynamic light scattering method. The apparatus used for the measurement is a dynamic light scattering particle size evaluation apparatus (DYNAMIC LIGHT SCATTERING PATRICLE SIZA ANALYZER) LB-500 manufactured by HORIBA, Ltd. Measurement conditions and parameters are as follows.
Distribution form: Monodispersed Data acquisition count: 100
Number of iterations: 100
Particle diameter standard: Volume Sample refractive index: 1.600-0.000i
Dispersion medium refractive index: 1.333
Dispersion medium viscosity: 0.8270mPa · s
Sample viscosity: 0.141V
Measurement temperature: 28.5 ℃

FIG. 5 is a measurement result of the particle size distribution of the nanocrystal diamond particles in the nanocrystal diamond particle dispersion, which is an example used in the present invention. It was found that the nanocrystal diamond particles in the dispersion had the following particle size distribution.
Arithmetic mean diameter: 0.0370μm
Arithmetic standard deviation: 0.0070μm
The nanocrystal diamond particles in the dispersion liquid agglomerate in the dispersion liquid over time after the dispersion liquid is formed, and the arithmetic average particle diameter gradually increases. If the arithmetic average particle size exceeds 100 nm (0.1 μm), it is not suitable for ultrasonic treatment with a nanocrystal diamond dispersion for forming the laminate of the present invention. Usually, after about 6 months have passed since the dispersion liquid was prepared, the aggregation of nanocrystal diamond particles progressed to a degree exceeding 100 nm. Therefore, it is suitable to form the present laminate by re-creating the nanocrystal diamond dispersion and using a new one about 6 months.

In the present invention, the substrate is immersed in the dispersion liquid of the nanocrystal diamond particles and applied to an ultrasonic cleaner. Using this ultrasonic physical impact force, specifically, an ultrasonic cleaner with a volume of 26 liters, the nanocrystal diamond particles collide with each other by the ultrasonic power with a frequency of 40 kHz and an output of 600 W. Alternatively, the material is pulverized by colliding with the base material or the adhesion reinforcing layer, and is further accelerated and collided toward the surface of the base material or the adhesion reinforcing layer by the impact force of ultrasonic waves. Of these, those given sufficient impact force bite into the substrate surface or adhesion reinforcing layer surface. The nanocrystal diamond particles that have digged into these surfaces function as anchors for the carbon layer to maintain high adhesion to the substrate surface or adhesion reinforcing layer surface. On the other hand, the nanocrystal diamond particles that have not been given a sufficient impact force adhere to the surface of the substrate or the adhesion reinforcing layer. These have the function of contributing to the growth of the carbon layer by the CVD process.
In order to effectively use the ultrasonic impact force, it is necessary to use an ultrasonic cleaner with an ultrasonic output of 4 W or more per liter of the ultrasonic cleaner capacity. In an ultrasonic cleaner with an output of less than that, it is difficult to obtain a high holding force on the substrate surface or the adhesion reinforcing layer surface because the impact force is small.

  After the ultrasonic treatment with the nanocrystal diamond dispersion liquid, the substrate provided with the substrate or the adhesion reinforcing layer is subjected to ultrasonic cleaning by immersing the substrate or the substrate provided with the adhesion reinforcing layer in ethanol, Remove and dry.

FIG. 6 shows the surface of a borosilicate glass substrate that has been subjected to ultrasonic treatment with the nanocrystal diamond dispersion and then immersed in ethanol for ultrasonic cleaning, taken out and dried, using an atomic force microscope. It is an observed photograph. It can be seen that the surface of the borosilicate glass substrate is covered with particles having a particle diameter of 10 nm to 50 nm.
As described above, it can be seen that high-density nanocrystal diamond particles are attached to or bite into the surface of the glass substrate by the ultrasonic treatment using the above-described nanocrystal diamond dispersion. In this figure, the density of the nanocrystal diamond particles biting into or adhering to the glass substrate surface was 5 × 10 ¹⁰ particles / cm ² . In order to obtain the adhesion strength of the carbon layer that can be used as an abrasive or abrasive to be described later to the glass substrate, the laminate of the glass substrate and the carbon layer is biting into or adhering to the surface of the glass substrate. The density of the nanocrystal diamond particles is preferably 10 ⁹ to 10 ¹² particles / cm ² , more preferably 10 ¹⁰ to 10 ¹¹ particles / cm ² .

In the present invention, after the nanocrystal diamond particles are provided on the substrate or the adhesion reinforcing layer, the treatment is performed using a microwave plasma CVD apparatus.
In the present invention, the supply source of the SiO ₂ material or Al ₂ O ₃ material and the substrate obtained in the above step are installed inside the microwave plasma CVD reactor, and the substrate is room temperature during the CVD process. To 500 ° C.
In the microwave plasma CVD reactor, a mixed gas of carbon-containing gas and argon gas and / or hydrogen gas is introduced as a reaction gas, and plasma is generated at a gas pressure of 1 to 100 Pa . The substrate is arranged at a position where the plasma electron temperature is 0.5 to 3.0 eV, and the radical particles in the plasma reach the substrate from the origin of the plasma so as to reach the surface of the substrate almost uniformly. This is achieved by adopting a carbon layer deposition method that is moved toward the surface.

About the manufacturing method of the laminated body of this invention, an example is given and an outline is demonstrated below.
For example, a material such as glass, silicon, iron and iron-based alloy, stainless steel, aluminum, copper, plastic, etc. is provided with an adhesion strengthening layer as necessary, or further after pretreatment by ultrasonic treatment of diamond fine particles From the origin of the plasma so that the radical particles in the plasma, which is the source of the film formation, reach the surface of the base material placed on the sample stage almost uniformly with a low-temperature microwave plasma CVD apparatus. The plasma CVD process is performed by supplying the gas by a down flow that moves toward the substrate.

In the case of substrates such as glass and silicon, the surface of these substrates is directly subjected to ultrasonic treatment using a dispersion of nanocrystal diamond particles to form nanocrystal diamond particles that bite or adhere to the substrate surface. To do. Thereafter, by applying a treatment to these substrates using a microwave plasma CVD apparatus, the adhesion strength of the carbon layer necessary for polishing and grinding can be obtained.
In addition, even materials such as iron and iron-based alloys, stainless steel, aluminum, copper, plastics, etc., are biting into the substrate surface by subjecting these substrate surfaces to ultrasonic treatment using a nanocrystal diamond dispersion directly. A carbon layer can be formed by forming attached nanocrystal diamond particles and then treating these substrates using a microwave plasma CVD apparatus.

However, with materials such as iron and iron-based alloys, stainless steel, aluminum, copper, and plastic, it is difficult to obtain high adhesion strength to the base material of the carbon layer necessary for polishing and grinding. For this type of substrate, an adhesion enhancing layer is provided on the surface of the substrate, and the surface of the adhesion enhancing layer is subjected to ultrasonic treatment using a nanocrystal diamond dispersion on the surface of the adhesion enhancing layer. The technique of forming nanocrystalline diamond particles that have penetrated or adhered to the substrate is very effective in obtaining the adhesion strength of the carbon layer to these substrates. For example, titanium (Ti), titanium nitride (TiN), silicon carbide (SiC), silicon nitride (Si ₃ N ₄ ), or the like is effective as the adhesion reinforcing layer of the carbon layer to these base materials. These adhesion reinforcing layers can be provided on the surface of the base material by using a sputtering method, a vacuum deposition method, or the like. The thickness of these adhesion reinforcing layers is suitably about 1 μm.

The plasma CVD processing time is several minutes to several tens of hours, and the processing temperature is 20 to 500 ° C.
In the present invention, the gas pressure of the plasma CVD process and the position where the base material is disposed are very important, and were confirmed as follows.

FIG. 7 shows an example of an apparatus used for forming a laminate according to the present invention.
In the figure, 101 is a microwave plasma CVD reactor (hereinafter simply referred to as “plasma generation chamber”), 102 is a rectangular waveguide with a slot for introducing microwaves into the plasma generation chamber 101, and 103 is a microwave. Is a quartz member for introducing the substrate into the plasma generation chamber 101, 104 is a metal support member for supporting the quartz member, 105 is a substrate for film formation, and 106 is a sample stage for installing the film formation substrate, A vertical movement mechanism and a film formation substrate cooling mechanism are provided, and reference numeral 107 denotes a cooling water supply / drainage. Reference numeral 108 denotes exhaust gas, and reference numeral 109 denotes plasma generation gas introduction means. 110 is a reactor for performing plasma CVD processing.

Plasma generation using the apparatus is performed as follows.
The plasma generation chamber 101 is evacuated by an exhaust device (not shown). Subsequently, a plasma generating gas is introduced into the plasma generating chamber 101 through the plasma generating chamber gas introducing means 109 at a predetermined flow rate. Next, a pressure control valve (not shown) provided in the exhaust device is adjusted to maintain the plasma generation chamber 101 at a predetermined pressure. By supplying a microwave of a desired power from a 2.45 GHz microwave generator (not shown) into the plasma generation chamber 101 through the slotted rectangular waveguide 102 and the quartz member 103, the plasma generation chamber Plasma is generated in 101. Thereby, the radical particles in the plasma that is the source of film formation reach the surface of the resin substrate placed on the sample stage almost uniformly, so that the quartz member 103 for introducing microwaves that is the source of the generation of the plasma It can be moved from the lower surface (CVD process reactor side) toward the substrate and supplied by downflow.

FIG. 8 shows the distance dependence of the electron temperature (electron kinetic energy) in the plasma from the lower surface of the quartz window for introducing microwaves (on the CVD reactor side) obtained by measuring the plasma characteristics using a Langmuir probe. The Langmuir probe used for the plasma characteristic measurement was a probe L2P type for plasma diagnosis manufactured by Kobe Steel. At this time, in order to accurately measure the plasma density and electron temperature of the electrodeless discharge plasma excited by microwaves, the measurement was performed by a technique called a double probe method using two probes of platinum and tungsten. The Langmuir probe method is described in detail, for example, in the document “Hideo Sakurai, Plasma Electronics, Ohmsha 2000, p.58”.
The gas used for the measurement in this figure is 100% hydrogen and the pressure is 10 Pa. Thus, the electron temperature in the plasma has a characteristic that it decreases as the distance from the quartz window increases. FIG. 9 shows the dependence of the plasma density on the distance from the bottom surface (CVD reactor side) of the quartz window for introducing microwaves.
In addition to the above measurements, methane gas 0.5-10 mol%, carbon dioxide gas 0-10 mol%, hydrogen gas 0-95.5 mol%, argon gas 0-95.5 mol% are mixed in an arbitrary ratio. Electron temperature and plasma density were measured. As a result, the plasma characteristics hardly changed in the measured gas mixing range.

The base material is placed on a sample stage that can move up and down so that the base material can be placed at an arbitrary position from the quartz window. The electron temperature in the plasma shown in FIG. 8 and that shown in FIG. Based on the plasma density data, hydrogen and other gases necessary for CVD treatment are filled into the plasma generation chamber, and the film formation experiment is carried out by changing the position of the resin substrate at a gas pressure of 10 Pa. We searched for conditions of electron temperature and plasma density. The gas necessary for the CVD process will be described in detail later.
As a result, it was found that no film was formed at the position of the substrate where the electron temperature was 3 eV or higher, or only a ridge-like film was deposited rather than the carbon layer of the present invention. For example, at a pressure of 10 Pa shown in FIG. 5, a region having a distance of 20 mm or less from the quartz window was a region where no film was formed or a ridge-like film was slightly deposited.
On the other hand, formation of the carbon layer of the present invention was confirmed in the region where the electron temperature was 3 eV or less. For example, it was confirmed that the film was formed in an area of 20 mm to 200 mm at a pressure of 10 Pa. When the pressure was 10 Pa, the electron temperature was 3 eV to 0.8 eV in this region.
Since the maximum movable range of the sample stage used in this experiment is 200 mm, the experiment could not be performed at a distance longer than this, but by experimenting with the sample stage, the experiment was performed at a larger distance. Is possible.

  In the region where this film formation was confirmed, the film formation speed reached its maximum when the distance from the quartz window was 50 mm to 70 mm. This is the dependence of the plasma density in FIG. 9 on the distance from the quartz window. Since the plasma density is maximum at 50 mm, it can be explained that the film formation speed becomes maximum at about 50 mm. Therefore, when it is desired to increase the film forming speed as much as possible, it has been clarified that the optimum position of the base material for film formation is a position where the electron temperature is 3 eV or less and the plasma density is maximized.

The above experiment was conducted at various gas pressures. As a result, it was found that the gas pressure suitable for deposition of the carbon layer was 1 to 100 Pa, preferably 1 to 50 Pa. When the gas pressure was 200 Pa or higher, film formation could not be confirmed. This is presumably due to the fact that the substrate is thermally damaged, thermally expanded, and thermally deformed by heating from the plasma because the gas pressure is high. Also, these experiments revealed that the optimal base material position for film formation varies depending on the gas pressure in the plasma CVD process. It was revealed that the carbon layer can be deposited on the substrate when the substrate is placed at a position where the plasma electron temperature is 0.5 to 3 eV at each gas pressure.
The position of the base material suitable for film formation can be selected because the radical particles in the plasma, which is the source of film formation, reach the surface of the base material placed on the sample stage almost uniformly. By moving the plasma from the origin of the plasma toward the substrate, an electron temperature distribution that gradually decreases from the origin of the plasma toward the substrate can be formed as shown in FIG. It depends.

In the present invention, the raw material gas (reactive gas) used for the CVD process is a mixed gas composed of a carbon-containing gas and argon gas and / or hydrogen. Examples of the carbon-containing gas include methane, ethanol, acetone, methanol and the like.
The mixing ratio of the mixed gas suitable for film formation varies depending on each substrate used for the substrate, and also varies depending on the surface treatment state of the substrate, but the concentration of the carbon-containing gas is 0.5 to 10 mol%. , Preferably 1 to 4 mol%. If the carbon-containing gas exceeds the above range, problems such as a decrease in the adhesion strength of the carbon layer to the substrate occur, which is not preferable.
Further, the mixed gas as additive gas, is preferably added to CO ₂ and CO. These gases act as an oxygen source, and exhibit an action of removing impurities in the plasma CVD process. The amount of CO ₂ and / or CO added is preferably 0.5 to 10 mol%, more preferably 1 to 5 mol% in the total mixed gas.
Addition of argon gas and / or hydrogen is extremely effective in preventing surface plasma damage when the substrate is a plastic material. In particular, when a plasma resistant film is not provided on the surface of the resin, increasing the proportion of argon gas compared to the proportion of hydrogen is effective in preventing plasma damage. The proportion of hydrogen gas is suitably 0 to 95.5 mol%, and the proportion of argon gas is suitably 0 to 95.5 mol%.

Further, in this CVD process, a substance for suppressing the generation of impurities such as amorphous carbon and graphite generated with the generation of the carbon particles forming the carbon layer and / or suppressing the growth of the carbon particles is used. It is necessary to supply the raw material gas to the CVD processing chamber together with carbon-containing gas, argon gas and / or hydrogen gas, and if necessary, CO ₂ and / or CO. In the present invention, the optimum substance for suppressing the generation of impurities such as amorphous carbon and graphite generated with the generation of the carbon particles forming the carbon layer and / or suppressing the growth of the carbon particles is SiO ₂ material or It was an Al ₂ O ₃ material.

In the plasma CVD method for forming the laminate of the present invention, quartz is used as the material of the member 103 for introducing the microwave into the plasma generation chamber 101. This quartz is used as a source of SiO ₂ material, which is an amorphous substance for suppressing the generation of impurities such as amorphous carbon and graphite generated with the generation of carbon particles and / or suppressing the growth of carbon particles. Plays an important role.
That is, when the quartz tube is exposed to the source gas that has been turned into plasma by the microwave, Si gas and oxygen gas are generated and become plasma together with the source gas. These plasmas are denser as they are closer to the quartz tube, and the spread due to diffusion is substantially in the direction of the substrate. At the same time as the diffusion, they are supplied to the substrate together with the source gas in a down flow more efficiently. The supply amount is controlled by adjusting the gas pressure in the CVD chamber to control the plasma density and by adjusting the production rate of Si gas and oxygen gas. When the concentration of Si gas is adjusted so as to be the same as the concentration of methane gas, the generation of impurities such as amorphous carbon and graphite that occur with the generation of carbon particles is suppressed, and / or the growth of carbon particles is suppressed. The highest suppression effect was revealed by gas concentration analysis. For example, the concentration of methane gas and the concentration of CO ₂ and Si gas are adjusted to be equal in the range of 1 to 5 mol%, and the remaining gas mixture ratio of hydrogen gas is very suitable for forming the laminate of the present invention. It was.

Further, alumina (Al ₂ O ₃ ) can be used as a material of the member 103 for introducing the microwave into the plasma generation chamber 101. In this case, alumina functions as a substance that suppresses the generation of impurities such as amorphous carbon and graphite that are generated along with the generation of carbon particles and / or suppresses the growth of carbon particles.

Further, as will be described later, the amorphous material is heated to a low temperature in the furnace, preferably from room temperature to be deposited and coated at a high density in the grain boundaries of the carbon particles and / or the voids between the carbon particles. It is desirable to form the film under a temperature condition of 600 ° C., more preferably room temperature to 450 ° C. Outside these temperature ranges, formation of amorphous substance Si and / or SiO ₂ was not observed. The mechanism of the amorphous substance formation and Si / or SiO ₂ is as follows. As the carbon particles are formed, Si that tends to dissolve in the carbon particles precipitates on the surface of the carbon particles because of the low temperature. The Si deposited on the surface is deposited as amorphous Si as it is on the particle surface, that is, at the grain boundaries of carbon particles and / or the voids between the carbon particles, or is oxidized by oxygen in the plasma and becomes amorphous SiO ₂ is deposited and coated. So far, formation of Si and / or SiO ₂ which is an amorphous substance has been confirmed by a CVD process at a low temperature up to room temperature.

  As a result of observing the surface of the carbon layer deposited on the base material with an optical microscope as described above, it becomes clear that it is difficult to uniformly form the carbon layer on the base material when the film thickness is 50 nm or less. It was. When the film thickness is 50 nm or more, the carbon layer can be uniformly formed on the substrate, but when the film thickness is 100 nm or more, it is clear that the carbon layer can be formed more uniformly on the substrate. It became. When the film thickness was 10 μm or more, the deposited carbon layer was easily peeled off from the substrate. When the film thickness was 5 μm or less, a carbon layer having adhesiveness sufficiently withstanding an adhesion strength test using a scotch tape could be formed on the substrate. Therefore, the film thickness of the carbon layer suitable for forming a laminate of the substrate and the carbon layer was 50 nm to 10 μm, preferably 100 nm to 5 μm.

According to the present invention, a laminate of a carbon layer and a substrate can be formed. In the X-ray diffraction spectrum by CuK _α1 ray, this carbon layer has a peak fitting curve A of 43.9 ° with a Bragg angle (2θ ± 0.3 °) of 41.7 ± as seen in FIG. It has a remarkable characteristic different from other carbon particles such as diamond and a carbon layer that it has an approximate spectral curve obtained by superimposing a peak fitting curve B of 0.3 ° and a base line.
Further, the carbon layer of the laminate is excellent in flatness and adhesion, and its surface roughness Ra is 20 nm or less, and in some cases, it is a flat one reaching 3 nm or less.

  Further, from observation of the cross section of the laminate film of the present invention with a high-resolution transmission electron microscope, the carbon layer is formed by filling crystalline carbon particles having a particle size of 1 nm to several tens of nm without any gaps, and the carbon layer It was found that the particle size distribution was not changed (average particle size was almost equal) at the interface between the substrate and the substrate, in the carbon layer and in the vicinity of the outermost surface of the carbon layer. The film thickness of the obtained carbon layer is preferably 2 nm to 100 μm, more preferably 50 to 500 nm, and the particle diameter of the particles is preferably 1 to 100 nm, and more preferably 2 to 20 nm.

  The cross section of the laminate of the present invention was observed with a high resolution transmission electron microscope (HRTEM). The HRTEM apparatus used was an H-9000 transmission electron microscope manufactured by Hitachi, Ltd., which was observed at an acceleration voltage of 300 kV. The sample holder used was a standard inclined sample holder of the HR-TEM apparatus. For the preparation of observation samples, (1) thinning by Ar ion milling, (2) thinning by focused ion beam (FIB) processing, or (3) stripping the carbon layer surface with a diamond pen Was collected by a microgrid.

Examples of observation results are shown in FIGS. 10 to 12 are observation examples of a carbon layer cross section on a glass substrate. In this case, a sample was prepared by ion milling. 10 is an electron microscopic image of the carbon layer cross section, FIG. 11 is an electron diffraction image of the carbon layer, and FIG. 12 is an electron energy loss spectroscopy (EELS) spectrum at the carbon K shell absorption edge of the carbon particles constituting the carbon layer. It is a measurement result.
From FIG. 10, it can be seen that the entire cross section of the carbon layer is filled with no gaps.
Also, the electron diffraction image of FIG. 11 is close to a ring pattern of randomly oriented polycrystalline diamond. However, especially in the ring corresponding to the diamond (111) plane, there are a lot of diffraction spots that do not ride on one ring. Correspond. In this respect, the carbon layer is significantly different from ordinary diamond. Furthermore, crystal particles having a particle size of about 5 nm are present in the carbon layer. It was also observed that one particle was composed of one or more crystallites.
From the EELS spectrum of FIG. 12, there is almost no peak corresponding to the π-π ^* transition indicating the presence of the CC sp ² bond, and the peak corresponding to the σ-σ ^* transition indicating the presence of the sp ³ binding component is dominant. I understand that. That is, it can be seen that the carbon layer is composed of crystalline carbon particles composed of sp ³ bonded carbon atoms.

Here, the crystallite is a microcrystal that can be regarded as a single crystal, and generally one grain is composed of one or a plurality of crystallites. From the results of HRTEM observation, the size (average particle size) of the carbon particles (crystallites) in the carbon layer was unchanged in the interface with the substrate, in the film, and on the outermost surface, and was in the range of 2 to 40 nm.
Here, when it can be considered that the particles are packed without gaps and the carbon layer is formed, the average particle size was determined according to the following procedure.
That is, the average particle size was determined by taking the average particle size of at least 100 different particles (crystallites) in a transmission electron micrograph of a carbon layer cross section. In FIG. 10, the portion surrounded by the white closed curve is one particle, and when the area surrounded by the closed curve is obtained and this value is S, the particle diameter D is
Determined by. Here, π represents a circumference ratio.
In addition, the surface density d _s of a particle is calculated from the average particle diameter of the particle.
d _s = unit area / (π × (average particle size / 2) ² )
Determined by.
Thus, when the surface density of the carbon layer of the laminate of the present invention is determined, the interface, in the film, and the outermost surface are not changed, and are in the range of 8 × 10 ¹⁰ / cm ² to 4 × 10 ¹² / cm ^2. I understood that.

Further, the cross section of the laminate of the present invention was sliced by ion milling, and the film structure and element distribution were observed using a high-resolution transmission electron microscope and electron energy loss spectroscopy (EELS).
First, when EELS spectra were observed in a region of about Φ100 nm at various locations in the film, Si was observed at all measurement points. It was also found that there was a difference in the amount of Si depending on the measurement location.
In addition, in order to investigate the element distribution in the minute region, detailed EELS measurement was performed and detailed analysis of the spectrum was performed. In the EELS spectrum, a peak due to Si (silicon) near 120 eV and a signal due to O (oxygen) near 530 eV are prominent in C (carbon) near 300 eV. FIG. 13 schematically shows a high-resolution transmission electron micrograph of the measured sample. Measurement point 1 is one carbon particle, measurement point 2 is a surface portion of the carbon particle, and measurement point 3 is a portion that is not a carbon particle slightly seen in the film.
From the shape of the peak of the EELS spectrum, the measurement point 1 is Si and C that are not SiO ₂ , the measurement point 2 is SiO ₂ and C, and the measurement point 3 is SiO ₂ and C. Therefore, it can be seen that in the carbon layer of the laminate of the present invention, SiO ₂ exists on the surface of the carbon particles forming the carbon layer, and is preferably formed so as to surround the carbon particles. Further, in the diffraction image of FIG. 11, a diffraction ring indicating the presence of crystalline SiO ₂ was not observed. Therefore, it was found that these SiO ₂ exist as amorphous in the carbon layer. In the carbon layer of the laminate of the present invention, amorphous SiO ₂ is present on the surface of the carbon particles forming the film, and is preferably formed so as to surround the carbon particles. Such a characteristic structure of the carbon layer was realized for the first time in the carbon layer of the laminate according to the present method, and was not found in a conventional diamond or diamond-like carbon film.
This amorphous SiO ₂ suppresses the generation of impurities such as amorphous carbon and graphite generated along with the generation of the carbon particles at the grain boundaries of the carbon particles and / or the gaps between the carbon particles, and / or suppresses the growth of the carbon particles. As a material for this, it plays a very important role.

In addition, it was confirmed that crystalline substances were scattered in the amorphous substance in the region of about 10 to 20 nm in the lowermost layer (immediately above the base material) of the carbon layer of the laminate of the present invention. From the shape of the peak of the EELS spectrum, it was found that the substances forming the region of about 10 to 20 nm of the lowermost layer (measurement point 4, measurement point 5) of FIG. 13 are SiO ₂ and C. From the analysis of diffraction images, it was found that SiO ₂ was amorphous and C was crystalline diamond. Therefore, in the region of about 10 to 20 nm of the lowermost layer of the carbon layer, nanocrystal diamond particles are eroded or adhered to the substrate surface by applying nanocrystal diamond particles to the substrate surface by ultrasonic treatment and further performing CVD treatment. It was revealed that diamond particles and amorphous SiO ₂ existing so as to fill the gaps between the particles were formed. The amorphous SiO ₂ present in the lowermost layer of the carbon layer is formed of amorphous carbon, graphite, or the like generated along with the formation of carbon particles at the grain boundaries of the nanocrystal diamond particles, the grain boundaries of the carbon particles, or the voids between the carbon particles. As a substance for suppressing the generation of impurities and / or suppressing the growth of carbon particles, it plays a very important role.
The amorphous SiO ₂ was present in a large amount in the region of about 10 to 20 nm in the lowermost layer of the carbon layer, and was about 50 atomic % or more. The amount of amorphous SiO ₂ decreases from the lower layer on the substrate side of the carbon layer toward the upper layer, and it is found that the carbon particles are 70 atom % or more at least 80 nm or more from the substrate of the carbon layer. It was.

As described above, in the laminate of the present invention, the region of about 10 to 20 nm in the lowermost layer (immediately above the substrate) of the carbon layer is eroded or adhered to the substrate surface by applying nanodiamond particles by ultrasonic treatment. It was found to be formed by crystal diamond particles and amorphous SiO ₂ existing so as to fill the gaps between the particles.
In this structure of the laminate of the present invention, the nanocrystal diamond particles that have digged into the surface of the base material function as an anchor that strengthens the adhesion of the carbon layer to the base material or adhesion reinforcing layer, and the surface of the base material or adhesion reinforcing layer. The nanocrystal diamond particles adhering to the carbon function as carbon particles for contributing to the growth of the carbon layer. Thus, in the laminate of the present invention, these nanocrystal diamond particles exhibit a great effect of promoting the growth of the carbon film and further improving the adhesion.
Furthermore, the adhering nanocrystal diamond particles and the amorphous SiO ₂ that exists so as to fill the gaps between the particles are formed in the grain boundaries of the nanocrystal diamond particles, the grain boundaries of the carbon particles, and / or the voids between the carbon particles. It functions as a substance for suppressing the generation of impurities such as amorphous carbon and graphite generated along with the generation and / or suppressing the growth of carbon particles. Furthermore, the amorphous SiO ₂ also has an auxiliary function for increasing the adhesion between the substrate and the carbon layer. In particular, by using the method of the present invention, an adhesion reinforcement layer is not provided even on a base material such as iron or copper, which is originally effective for depositing a carbon layer with high adhesion. The carbon layer can be deposited with a certain degree of adhesion. This is because the amorphous SiO ₂ assists the anchor effect of the nanocrystal particles that bite into the substrate and plays a function of further increasing the adhesion of the carbon layer to the base material.

In order to investigate the distribution of amorphous SiO ₂ having the above effects in the carbon layer, the concentration of silicon and oxygen in the carbon layer and in the vicinity of the interface with the base material is determined by the secondary ion mass. It was measured by analysis (SIMS). FIG. 14 shows the distribution in the depth direction of the silicon (Si) and oxygen (O) films contained in the carbon layer of the laminate of the present invention, as measured by SIMS. In this laminate, the base material is Si. The thickness of the carbon layer was approximately 0.7 μm. From FIG. 14, it was found that both silicon and oxygen have a substantially constant concentration in the carbon layer. The concentrations of silicon and oxygen near the center of the carbon layer thickness (0.37 μm) were 6.17 × 10 ²¹ / cm ³ and 1.00 × 10 ²² / cm ³ , respectively. Therefore, the ratio of the concentration of silicon and oxygen is 1.23: 2. This is because, in the carbon layer of the laminate of the present invention, SiO ₂ is a carbon layer, as has been clarified by observation of the structure and element distribution of the film by the above-described high-resolution transmission electron microscope and electron energy loss spectroscopy (EELS). In addition to being formed so as to surround the carbon particles and further containing Si in the carbon particles, the number of atoms of silicon and oxygen in SiO ₂ This is because the silicon is displaced in the direction in which the silicon is larger than the ratio 1: 2. Moreover, since the density of the film is about 1.76 × 10 ²³ / cm ³ , the average concentration of SiO _{2 in} the carbon layer is about 3.5%.
On the other hand, in the vicinity of the lowermost layer on the silicon substrate side of the carbon layer of the laminate of the present invention (the depth from the laminate surface is around 0.7 μm), the oxygen distribution has a peak. And in the deeper part, the oxygen concentration becomes very small, and it can be seen that the part is in the silicon substrate. As is apparent from the above EELS measurement, oxygen is present in the carbon layer as SiO ₂ . Therefore, from this SIMS measurement, it is found that in the laminate of the present invention, the concentration of SiO ₂ (amount per unit volume) is much higher in the vicinity of the lowermost layer on the silicon substrate side of the carbon layer than in the central portion of the carbon layer. It was. As estimated from the peak value of oxygen distribution, 3.78 × 10 ²² / cm ³ , the SiO ₂ content in the lowermost layer of the carbon layer is approximately 21%. In the film structure and element distribution observation by the above-described high-resolution transmission electron microscope and electron energy loss spectroscopy (EELS), there is a lot of amorphous SiO _{2 in} the lowermost layer of the carbon layer, and the lower part of the carbon layer on the substrate side It became clear that it had a distribution decreasing from the upper layer toward the upper layer, but this characteristic distribution was also confirmed in this SIMS measurement.

The carbon layer of the laminate of the present invention was observed by X-ray diffraction. Details of the measurement are described below. The X-ray diffractometer used was Rigaku Corporation's X-ray diffractometer RINT2100 XRD-DSCII, and the goniometer was a Rigaku Ultima III horizontal goniometer. A multipurpose sample stand for thin film standard is attached to this goniometer. The measured sample is a carbon layer having a thickness of 500 nm prepared on a borosilicate glass substrate having a thickness of 1 mm by the above method. A glass substrate cut into a 30 mm square was measured. As the X-ray, a copper (Cu) Kα ₁ line was used. The applied voltage / current of the X-ray tube was 40 kV / 40 mA. A scintillation counter was used as the X-ray detector. First, the scattering angle (2θ angle) was calibrated using a silicon standard sample. The deviation of the 2θ angle was + 0.02 ° or less. Next, the measurement sample is fixed to the sample stage, and the 2θ angle is 0 °, that is, the X-ray incident direction is parallel to the sample surface under the condition that the X-ray is directly incident on the detector. It was adjusted so that half was blocked by the sample. The goniometer was rotated from this state, and X-rays were irradiated at an angle of 0.5 degrees with respect to the sample surface. The incident angle was fixed, the 2θ angle was rotated from 10 ° to 90 ° in steps of 0.02 ° , and the intensity of X-rays scattered from the sample at each 2θ angle was measured. The computer program used for the measurement is RINT2000 / PC software Windows (registered trademark) version manufactured by Rigaku Corporation.

The measured X-ray diffraction spectrum is shown in FIG. White circles in the figure are measurement points. It can be seen that there is a clear peak at 2θ of 43.9 °. What is interesting here is that, as can be seen from FIG. 15, the peak at 43.9 ° has a shoulder at the low angle side, 2θ of 41 to 42 °. (For the “shoulder” of the spectrum, refer to “Chemical Dictionary” (Tokyo Kagaku Dojin).) Therefore, this peak is a peak centered around 43.9 ° (first peak) and 41 to 42 °. Another peak (second peak) distributed around is composed of two component peaks. Diamond is known as a carbon-based material having a peak at 2θ of 43.9 ° by X-ray diffraction using CuKα ₁ rays. Here, FIG. 16 shows a spectrum obtained by X-ray diffraction measurement of diamond by the same method, and the peak is due to (111) reflection of diamond. The difference in the X-ray diffraction spectrum between the carbon layer of the laminate of the present invention and diamond is clear, and the second peak distributed around 41 to 42 ° seen in the spectrum of the carbon layer of the present invention can be seen in diamond. Can not. Thus, the (111) reflection of diamond is composed of one component (only the first peak) centered at 43.9 °, and the shoulder on the low angle side like the carbon layer of the laminate of the present invention is not observed. Therefore, the 2nd peak distributed around 41-42 degrees seen in the spectrum of the carbon layer of the layered product of the present invention is a peak characteristic of the carbon layer of the layered product of the present invention.

Further, it can be seen that the peak of the X-ray diffraction spectrum of the carbon layer of the laminate of the present invention shown in FIG. 15 is much wider than the peak of the diamond shown in FIG. In general, when the size of the particles constituting the film is reduced, the width of the X-ray diffraction peak is increased, and it can be said that the size of the particles constituting the carbon layer of the laminate of the present invention is very small. When the size (average diameter) of the carbon particles constituting the carbon layer of the laminate of the present invention is estimated from the peak width by the Scherrer formula usually used in X-ray diffraction, it is about 15 nm. It was. For the Scherrer formula, refer to, for example, “Thin Film Handbook edited by Japan Society for the Promotion of Science, Thin Film 131st Committee, Ohmsha 1983, p. 375”.
Next, details of the configuration of the peak (position and intensity of each peak component, etc.) will be seen.

In order to know the detailed structure of the peak of 2θ of 43.9 ° in the X-ray diffraction measurement of the carbon layer of the laminate of the present invention, the 2θ angle was analyzed between 39 ° and 48 ° using peak fitting. . For fitting the first peak, a function called a Pearson VII function was used. This function is most commonly used as a peak profile of diffraction methods such as X-ray diffraction and neutron diffraction. Regarding this Pearson VII function, it is recommended to refer to “Practice of Powder X-ray Analysis—Introduction to Rietveld Method” (edited by the Japan Society for Analytical Chemistry X-ray Analysis Research, Asakura Shoten). Further, as a result of examining various functions, it has been found that an asymmetric function should be used for fitting the second peak. Here, an asymmetric normal distribution function (Gaussian distribution function) was used. This function is a normal distribution function with different dispersion (standard deviation) values on the right and left sides of the peak position, and is one of the simplest functions used for fitting asymmetric peaks, but very well peak fitting I was able to. A linear function (linear function) was used as the baseline (background) function.

  Although various computer programs can be used for the actual fitting work, the ORIGIN version 6 Japanese version peak fitting module (hereinafter, ORIGIN-PFM) was used here. In ORIGIN-PFM, the Pearson VII function is expressed as “Pearson7”, the asymmetric normal distribution function as “BiGauss”, and the linear function as “Line”. The fitting completion condition was that the correlation coefficient (ORIGIN-PFM “COR” or “Corr Coef”) representing the fitting reliability was 0.99 or more.

  As a result of the analysis using the peak fitting, as shown in FIG. 15, the measured spectrum has a first peak by the Pearson VII function (fitting curve A in the figure), a second peak by the asymmetric normal distribution function (fitting curve B in the figure), It was also found that the sum of the baseline (background) by a linear function (fitting total curve in the figure) can be approximated very well. In this measurement, the center of the fitting curve A is 2θ at 43.9 °, whereas the fitting curve B is maximum at 41.7 °. The area surrounded by each fitting curve and the baseline is the intensity of each peak. This analyzed the intensity | strength of the 2nd peak with respect to the intensity | strength of the 1st peak. In the case of this sample, the intensity of the second peak (fitting curve B) was 45.8% of the intensity of the first peak (fitting curve A).

  When many samples of the carbon layer of the laminate of the present invention were subjected to X-ray diffraction measurement, a wide peak as shown in FIG. 15 was observed with 2θ centering on 43.9 °. Moreover, it has a shape with a shoulder on the low angle side as shown in FIG. 13, and it was found to be constituted by the first peak and the second peak. When analysis by the same peak fitting was performed on X-ray diffraction spectra measured on a large number of samples, it was found that fitting was possible very well using the above-described function. The center of the first peak had 2θ of 43.9 ± 0.3 °. The second peak was found to be maximum when 2θ was 41.7 ± 0.5 °. The intensity ratio to the first peak was 5% minimum and 90% maximum. This intensity ratio is highly dependent on the synthesis temperature, and tends to increase as the temperature decreases. On the other hand, the position of the peak was almost constant regardless of the synthesis temperature.

  It should be noted that this X-ray diffraction measurement analysis method has a large variation in measurement data if the intensity of the X-ray is small, and reliable fitting is impossible. For this reason, it is necessary to perform the above-described analysis by fitting for those having a maximum peak intensity of 5000 counts or more.

As described above, the carbon layer of the laminate of the present invention has a wide peak with 2θ centering on 43.9 ° in the X-ray diffraction measurement by CuKα ₁ line, and the peak is shouldered on the low angle side. It became clear that it had a certain structure. According to the analysis using peak fitting, this peak is derived from the first peak by Pearson VII function centered at 2θ of 43.9 °, the second peak by asymmetric normal distribution function having the maximum at 41.7 °, and a linear function. It was found that the approximation of the baseline (background) can be approximated very well.

  Similar analysis by peak fitting was performed on the diamond spectrum shown in FIG. It was found that, unlike the carbon layer of the laminate of the present invention described above, in the case of diamond, it can be approximated very well only by the Pearson VII function centered at 2θ of 43.9 °. Therefore, it was found that the carbon layer of the laminate of the present invention is a substance having a structure different from that of diamond.

  The carbon layer of the laminate of the present invention is characterized in that the second peak described above is observed, and is a carbon layer having a structure different from that of diamond. The manufacturing process of the carbon layer of the laminate of the present invention and other measurement results were examined, and the structure was examined. When the method for synthesizing the carbon layer used in the present invention is compared with the CVD method for diamond, it has the following major features. First, normal diamond synthesis is performed at a temperature of at least 700 ° C., whereas the carbon layer of the laminate of the present invention is synthesized at a very low temperature. Conventionally, when the particle diameter of the diamond film is reduced, a method of growing at a high speed with a high concentration of about 10 mol% of the carbon source concentration (methane gas molar ratio) contained in the source gas has been used. The source concentration is as low as about 1 mol%. That is, in this method, carbon particles are deposited and a film is formed by taking time very slowly at a low temperature. Therefore, the carbon particles are deposited in a state where it is possible to become diamonds. For this reason, a force that promotes precipitation of hexagonal diamond, which is a crystal made of carbon that is more stable than ordinary cubic diamond, and more stable precipitation of graphite works, and the crystal deposition state is very unstable. Further, once precipitated graphite and amorphous carbon material are also removed by etching with a large amount of hydrogen plasma contained in the source gas. By such a precipitation mechanism, cubic diamond and hexagonal diamond are mixed and a portion removed by etching remains as a very high concentration defect. These defects include point defects such as atomic vacancies, linear defects such as dislocations, and a large amount of surface unit defects such as stacking faults. Therefore, the X-ray diffraction peak at 43.9 ° has a shoulder on the low angle side.

However, the characteristics of the X-ray diffraction peak as described above are linked to the high function of the carbon layer of the laminate of the present invention. That is, the slow synthesis at low carbon source concentrations facilitates the etching of relatively high and low materials such as graphite and graphite-like materials. For this reason, it becomes a structure containing a high concentration of defects, but on the other hand, the carbon film has achieved a high hardness, and because of the high polishing and grinding characteristics of the laminate of the present invention, very important features and It has become.
Also, because it is synthesized at low temperature, cubic diamond and hexagonal diamond are mixed and contain a high concentration of defects, but thanks to such low temperature synthesis, iron and iron alloys, aluminum, copper, Furthermore, it can be laminated on a substrate such as plastic. When the synthesis temperature of the CVD process is high, due to the difference in thermal expansion between the base material and the carbon layer, when the temperature is returned to room temperature after the CVD process, the base material shrinks more than the carbon layer, resulting in a large residual stress in the carbon film. Peeling of the carbon layer from the substrate occurs. In the method of the present invention, since the residual stress is small due to the synthesis at a low temperature, the adhesion of the carbon film to the substrate is increased. Furthermore, in the carbon layer of the laminate of the present invention, the fine particle diameters of the carbon particles are uniform, and the strain due to heat is very small. That is, the structure in which cubic diamond and hexagonal diamond are mixed and contains a very high concentration of defects alleviates thermal strain and realizes high adhesion to the substrate. Due to the above characteristics, high polishing and grinding characteristics of the laminate of the present invention are obtained.

  The surface roughness was evaluated by observing the surface of the carbon layer of the laminate of the present invention with an atomic force microscope (AFM). In this case, a quartz disk substrate having a small mirror-polished surface roughness (arithmetic average height Ra = 0.9 to 1.2 nm) in order to suppress the influence of the surface roughness of the substrate on the surface roughness of the film as low as possible. A carbon layer was formed on (diameter 10 mm × thickness 3 mm) to obtain a measurement sample. The AFM apparatus used was a Nanoscope scanning probe microscope manufactured by Digital Instruments, USA, and a cantilever single crystal silicon rotation probe Tap300 for scanning probe microscope manufactured by Veeco Instruments was used as the cantilever. Tapping mode was used for measurement, and observation was performed at a scan size of 1 μm × 1 μm and a scan rate of 1.0 Hz.

In FIG. 17, the observation result by the atomic force microscope (AFM) of the carbon layer surface of the laminated body of this invention is shown. The AFM equipment standard measurement and analysis computer software Nanoscope IIIa ver. 4.43r8 was used for image processing of observation results and evaluation of surface roughness. From the analysis of the observation result, the surface roughness of the carbon layer was 3.1 nm in Ra. A number of other samples were also evaluated, and it was confirmed that the surface roughness was in the range of 2.6 to 20 nm, although the surface roughness was different depending on the carbon layer deposition conditions. The surface roughness of the quartz disk substrate before the carbon layer was deposited was also measured in the same manner, and it was found that Ra was in the range of 0.9 to 1.2 nm.
The arithmetic average height Ra is described in detail in, for example, “JIS B 0601-2001” or “ISO4287-1997”.

In the polishing of a SiC single crystal using the laminate of the present invention, which will be described later, it has become clear that the surface roughness of the laminate, the polishing rate, and the finished surface roughness are closely related. That is, when the surface roughness of the laminate is reduced, the finished surface roughness of the object to be polished is reduced, and a very flat finished surface can be obtained, while the polishing rate is reduced. Conversely, when the surface roughness of the laminate increases, the polishing rate increases, but the finished surface roughness of the object to be polished increases and a flat surface cannot be obtained. This is presumably because the surface roughness of the laminate depends on the polishing resistance, that is, the friction coefficient. Therefore, the relationship between the surface roughness Ra and the friction coefficient of the laminate of the present invention based on glass was measured.
FIG. 18 shows the measurement results. The straight line in the figure is an approximate straight line of these measurement points, and the mathematical expression in the figure is an approximate expression representing the relationship between the surface roughness (x) and the friction coefficient (y). The coefficient of friction was measured using a load fluctuation type friction and wear tester (HSS2000) manufactured by Shinto Kagaku Co., Ltd. under the following conditions and analyzed using analysis software (TriboWare Rev. 1.8).
Measurement conditions: Reciprocating test
Load 2.0N
SUS440C ball with a diameter of 4.7mm
Oil lubrication Room temperature in base oil
Movement speed 20nm / s

As a result of considering the relationship between the obtained surface roughness and the friction coefficient, and the result of the polishing test, when the friction coefficient is less than 0.05, the polishing rate becomes very small and practical precision polishing is hardly achieved. When the friction coefficient is larger than 0.10, it has been clarified that precise polishing cannot be performed so that the surface roughness Ra is 0.5 nm or less.
Therefore, the surface roughness Ra of the laminate that enables practical precision polishing is in the range of 4 nm to 11 nm where the friction coefficient is 0.05 or more and 0.10 or less from FIG.

  As described above, since the surface roughness of the laminate greatly affects the polishing characteristics, a method for adjusting the surface roughness of the laminate is required. In particular, when Ra on the surface of the laminate is larger than 11 nm, it is desired that Ra, which can be used for practical precision polishing, can be adjusted in a range of 4 nm to 11 nm by reducing the surface roughness.

In the present invention, it has been found that the surface roughness is reduced by polishing with another laminate formed in the same manner after the formation of the laminate by CVD treatment. At this time, pure water or ethanol was dropped on the surfaces of both laminates, and the laminates were polished by reciprocating, rotating, or rotating eccentrically using the lubricant as a lubricant.
In the present invention, as a result of further diligent efforts, a hydrogen plasma is generated at a hydrogen gas concentration of 100 mol% and a gas pressure of 1 to 100 Pa, preferably 1 to 50 Pa using the same apparatus after forming a laminate by CVD treatment. The method of reducing the surface roughness of a laminated body was discovered by exposing the laminated body surface for 30 seconds to 5 minutes, preferably 1 minute to 3 minutes.

In order to see the effect of reducing the surface roughness due to the above polishing and hydrogen plasma, the surface roughness of each laminated body based on a silicon single crystal wafer was evaluated before and after each treatment. For the evaluation of the surface roughness, a surface shape measuring device SURFCORDER ET-4300 manufactured by Kosaka Laboratory Ltd. and surface fine shape analysis software iSTAR31 Version 6.72 were used. Measurement and analysis were performed with a cut-off value of 0.8 mm, a reference length of 4.0 mm, and an evaluation length of 4.0 mm. The results are shown in FIG. 21, FIG. 22, FIG. 23 and FIG.
FIG. 21 is a curve showing the surface shape of the laminate immediately after the CVD treatment, and from this, the surface roughness Ra was evaluated as 12.3 nm. FIG. 22 shows the surface shape as a result of rubbing the surface of this laminate with another similar laminate for about 1 minute, 100 reciprocations in a straight line and 100 reciprocations in a direction perpendicular thereto with an amplitude of about 10 mm. At this time, pure water was used as a lubricant. The surface roughness Ra obtained from FIG. 22 was 8.2 nm, and it was found that the surface roughness was clearly reduced.
FIG. 23 also shows the surface shape of the laminate immediately after the CVD process, and the surface roughness Ra in this case was 10.3 nm. FIG. 24 shows the surface shape when a laminate produced by the CVD process under the same conditions as the laminate of FIG. 23 is exposed to hydrogen plasma for about 3 minutes following the CVD treatment. The hydrogen plasma treatment was performed at 100 mol% hydrogen gas and a gas pressure of 20 Pa. The value of the surface roughness Ra evaluated from FIG. 24 is 5.0 nm, and it was found that the surface roughness was clearly reduced in this case as well.
In any case of the above polishing and hydrogen plasma treatment, the surface roughness Ra exceeds 11 nm, and the surface roughness can be sufficiently used for precision polishing by applying to a laminate that is not suitable for precision polishing. It was found that the surface roughness can be reduced to Ra of 4 to 11 nm.

Using the laminate of the present invention, single crystal silicon carbide, SiC, and a surface polishing test were conducted. A disk-shaped single crystal silicon having a diameter of 100 mm and a thickness of 0.5 mm was used as the base material of the laminate. This single crystal silicon base material was mirror-polished, and the surface roughness Ra measured with an atomic force microscope (observation field of view 1 μm square) was 1 nm or less before forming a laminate by CVD treatment. Nanocrystal diamond particles were provided on this surface by ultrasonic treatment, and the above-described CVD treatment was performed to deposit a carbon layer having a thickness of approximately 1 μm to form a laminate. Further, after forming the laminate by this CVD treatment, hydrogen plasma was generated using the same apparatus at 100 mol% hydrogen gas and a gas pressure of 20 Pa, and the surface of the laminate was exposed to the plasma for 3 minutes. As a result, a laminate surface roughness Ra of 5.0 nm as measured with an atomic force microscope was formed, and this was used as a polishing plate.
The sample used for the polishing test is an on-axis Si surface of 4H-SiC (0001) single crystal manufactured by CREE. The deviation angle and misorientation angle of this surface from the (0001) plane are 0.2 degrees or less. The surface before polishing was subjected to chemical mechanical polishing by the manufacturer, and the surface roughness Ra was 0.2 nm by atomic force microscope observation with an observation field of 1 μm square. This SiC single crystal was cut into a 10 mm square and used as a polished sample.
This silicon-based laminate polishing plate was fixed to a surface plate, cooled by applying cold water at 15 ° C., and ethanol was added dropwise as a polishing aid. A SiC single crystal polishing sample was pressed onto the surface of the polishing board with a finger, and was slowly rubbed by reciprocating linear motion of about 20 mm for 10 times. When pressed with a finger, the load applied to the SiC single crystal polished sample is approximately 20 g.
FIG. 19 shows an atomic force microscope observation result of the surface of the SiC polished sample after the polishing. The observation field is 1 μm square. The surface roughness Ra after polishing was 0.102 nm, and the surface flatness could be improved compared to before polishing. Further, as shown in the figure, a clear stripe-like contrast was observed in the atomic force microscope image. FIG. 20 shows the unevenness between the arrows in FIG. Thus, it can be seen that peaks and valleys corresponding to the striped contrast in FIG. 20 are formed. The average amplitude of the peaks and valleys is 0.278 nm, which is in good agreement with the atomic layer spacing of 0.251 nm on the (0001) plane of the 4H—SiC single crystal. Therefore, it was revealed that the stripe contrast in FIG. 19 is a stripe contrast corresponding to the atomic layer step on the surface of the 4H—SiC (0001) single crystal.
The flatness to the extent that the atomic layer step on the surface of the SiC single crystal is observed by the polishing machine using the laminate of the present invention as described above could not be realized at all by the conventional fixed abrasive type polishing machine. And shows the remarkable performance of the polishing machine using the laminate of the present invention.

  Also, the surface of the laminate was formed using single crystal silicon as the base material and surface roughness Ra adjusted to 6.0 nm and 7.0 nm, and this was used as a polishing plate to conduct polishing tests on single crystal silicon carbide, SiC, and the surface. It was. As a result, when a polishing disk having a surface roughness Ra of 6.0 nm is used, a clear fringe contrast corresponding to the atomic layer step is observed in the atomic force microscope image of the polished SiC surface as described above. It was done. On the other hand, when a polishing disk having a surface roughness Ra of 7.0 nm was used, stripe-shaped contrast corresponding to atomic layer steps could not be observed in the atomic force microscope image of the polished SiC surface. Therefore, in order to polish the 4H-SiC (0001) single crystal surface so flat that the atomic layer step is observed by an atomic force microscope, the surface roughness Ra of the polishing disk by the laminate of the present invention is 6 nm or less. I found that it was necessary. When the surface roughness Ra is smaller than 4 nm, the polishing rate becomes very small as described, and practical precision polishing is hardly achieved. Therefore, the surface roughness Ra of a practical polishing disk for polishing the 4H—SiC (0001) single crystal surface so flat that the atomic layer step is observed by an atomic force microscope is 4 nm to 6 nm.

From the above experiments, in the laminate of the present invention, the proportion of amorphous SiO _{2 in} the region of about 10 to 20 nm of the lowermost layer of the carbon layer is about 50 atomic % or more, and the amorphous SiO ₂ The amount decreases from the lower layer toward the upper layer on the substrate side of the carbon layer , the carbon particles are 70 atomic % or more at least 80 nm or more from the substrate of the carbon layer , and the surface roughness Ra is 4 nm to 6 nm. It became clear that the laminated body which exhibits the function outstanding as an abrasive | polishing material of a silicon carbide member can be formed by a typical structure.

  The excellent grinding and polishing functions of the laminate of the present invention as described above are shown in FIGS. 1 to 4 as a result of intensive studies on a laminate comprising a substrate or a substrate provided with an adhesion reinforcing layer and a carbon layer. This is an effect that has led to the finding of the structure of the laminated body, and has made it possible to form a carbon layer having high adhesion to a substrate as described in detail below, as well as high hardness and surface flatness.

  It is used in the field of manufacturing semiconductor elements, power elements and the like using silicon carbide and SiC as materials.

The figure which shows the laminated structure of the laminated body of this invention. The figure which shows the laminated structure of the laminated body of this invention. The figure which shows the laminated structure of the laminated body of this invention. The figure which shows the laminated structure of the laminated body of this invention. The figure which shows the particle size distribution of the nanocrystal diamond particle in the nanocrystal diamond dispersion liquid measured using the dynamic light scattering method. The surface of a borosilicate glass substrate that has been subjected to ultrasonic treatment with a nanocrystal diamond dispersion, as observed using an atomic force microscope. The figure which shows the structure of the manufacturing apparatus of the laminated body of this invention. The figure which shows the distance dependence from the lower surface (CVD reactor side) of the quartz window for microwave introduction of the electron temperature (electron kinetic energy) in the plasma obtained by the plasma characteristic measurement using a Langmuir probe. The figure which shows the distance dependence from the lower surface (CVD reactor side) of the quartz window for microwave introduction of plasma density. The cross section of the carbon layer of the laminated body of this invention observed with the high-resolution transmission electron microscope (HRTEM). The electron diffraction image of the carbon layer of the laminated body of this invention. Electron energy loss spectroscopy (EELS) spectrum (C-K shell absorption edge) diagram. The schematic diagram by the high-resolution transmission electron microscope observation of the cross section of the carbon layer right above a silicon substrate of the laminated body by the silicon substrate and carbon layer of this invention. The figure which shows the depth direction distribution of the film | membrane of the silicon (Si) and oxygen (O) which are contained in the carbon layer of the laminated body of the silicon base material of this invention and a carbon layer measured by secondary ion mass spectrometry. The figure which shows an example of the X-ray-diffraction spectrum by the CuK (alpha) ₁ X-ray of the carbon layer of the laminated body of this invention, and a peak fitting result. The figure which shows the typical X-ray-diffraction spectrum ((111) reflection peak) by CuK (alpha) ₁ X-ray in a diamond, and a peak fitting result. The carbon layer surface of the laminated body of the quartz base material (average surface roughness Ra = 0.87 nm) of this invention and a carbon layer (thickness 1.6 micrometers) observed with the atomic force microscope (AFM). The figure showing the relationship between surface roughness Ra of the laminated body of this invention, and friction coefficient (micro | micron | mu). 4H—SiC (0001) single crystal Si surface polished with the laminate of the present invention, observed with an atomic force microscope. The unevenness | corrugation between the arrows of the atomic force microscope image of the 4H-SiC (0001) single crystal Si surface grind | polished with the laminated body of this invention shown in FIG. Surface shape and surface roughness Ra of the laminate of the present invention measured using a surface shape measuring instrument. Surface shape and Ra of laminates whose surfaces are polished by the laminates of the present invention. Surface shape and Ra immediately after CVD treatment of the laminate of the present invention. Surface shape and Ra of the laminate of the present invention exposed to hydrogen plasma after CVD treatment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Plasma generation chamber 102 Square waveguide with a slot 103 Quartz member for microwave introduction 104 Metal support member which supports a quartz member 105 Film-forming base material 106 Sample stage for installing a film-forming base material 107 Supply / drainage of cooling water 108 Exhaust 109 Gas introducing means for generating plasma 110 Reactor

Claims (3)

A laminate that includes a carbon layer provided on the substrate and the base material, a polishing material for polishing a silicon carbide single crystal surface,
The carbon layer includes diamond fine particles which are provided on the base material and are pulverized by impact, amorphous SiO ₂ present so as to fill gaps between the diamond fine particles, carbon particles, and particles of the carbon particles. Consists of amorphous Si and / or SiO ₂ that suppresses the generation of impurities that are deposited and coated in the voids and / or voids between the carbon particles and inhibits the growth of carbon particles and / or suppresses the growth of carbon particles Has been
The proportion of amorphous SiO ₂ in the 10-20 nm region of the lowermost layer of the carbon layer is 50 atomic% or more, and the amount of this amorphous SiO ₂ is changed from the lower layer on the substrate side of the carbon layer to the upper layer. At least 80 nm or more of carbon particles from the substrate of the carbon layer, and
An abrasive for a silicon carbide single crystal surface , wherein the carbon layer has a surface roughness Ra of 4 nm to 6 nm . The substrate is silicon, quartz, glass, stainless steel, or abrasive silicon carbide single crystal surface according to claim 1, the Rukoto such from either aluminum characterized. The polishing material for a silicon carbide single crystal surface according to claim 1, wherein an adhesion reinforcing layer is provided between the base material and the carbon layer.