JP2012086988A - Process for exfoliating diamond - Google Patents

Abstract

An object of the present invention is to provide a diamond peeling method that improves the ion implantation step required in the diamond peeling process and realizes peeling at a lower cost.
An ion implantation step of implanting ions into a main surface of a diamond substrate (03) to form an ion implantation layer on the diamond substrate, and a diamond film (on the surface of the substrate on which the ion implantation layer (04) is formed) 02), and the structure obtained by the step including the step of forming the structure having the structure in which the ion implantation layer is sandwiched between the diamond layers (02, 03) is immersed in an etching solution. A diamond peeling method including a peeling step of separating the diamond layer by applying a voltage and electrochemically etching the ion implanted layer, wherein an implantation energy of 10 keV is used as the ion implantation layer in the ion implantation step. A diamond peeling method characterized by forming a layer thickness of less than 9.0 μm by multistage implantation of less than 1 MeV and two or more steps.
[Selection] Figure 1

Description

  The present invention relates to a diamond peeling method for peeling diamond having a large area suitable for a substrate for semiconductor devices and optical components in a relatively short time, and in particular, a diamond peeling method in which an ion implantation step required in the peeling process is improved. About.

  Since diamond has many excellent properties such as high hardness, high thermal conductivity, high light transmittance, wide band gap, etc., it is widely used as a material for various tools, optical parts, semiconductors, electronic parts, In the future, it will be even more important.

  As industrial applications of diamond, in addition to naturally occurring ones, artificially synthesized ones with stable quality are mainly used. At present, most of artificial diamond single crystals are synthesized industrially under a temperature environment of a few thousand degrees C to two hundreds of hundred degrees C, which is a stable existence condition of diamond, under a pressure environment of tens of thousands of atmospheres or more. Such an ultra-high pressure vessel that generates high temperature and high pressure is very expensive and has a limited size. Therefore, there is a limit to the synthesis of a large single crystal by the high temperature and high pressure method. As for the Ib type diamond having a yellow color containing nitrogen (N) as an impurity, a 1 cmφ class diamond is manufactured and sold by a high-temperature and high-pressure synthesis method. Further, the colorless and transparent type IIa diamond having no impurities is limited to a smaller one of several mmφ or less, except for natural ones.

  On the other hand, a gas phase synthesis method is established as a diamond synthesis method along with the high-temperature and high-pressure synthesis method. Although a relatively large area of about 6 inches φ can be formed by this method, it is usually a polycrystalline film. However, when using diamond for ultra-precision tools and optical parts that require a smooth surface, semiconductors that require precise control of impurity concentration and high carrier mobility, etc., use single crystal diamond. Become. Therefore, methods for obtaining single crystal diamond by epitaxial growth by vapor phase synthesis have been studied.

  In general, the epitaxial growth is considered to be homoepitaxial growth in which a growing material is grown on the same type of substrate and heteroepitaxial growth in which a growth material is grown on a different type of substrate. In heteroepitaxial growth, diamond has been considered difficult until now, but in recent years, as described in Patent Document 1, a 1-inch φ heteroepitaxial diamond free-standing film has been produced, and significant progress has been made. However, the crystallinity of the obtained single crystal is not sufficient as compared with the homoepitaxial diamond single crystal, and single crystal synthesis by homoepitaxial growth is considered to be promising.

  In homoepitaxial growth, a large IIa single crystal diamond exceeding the IIa diamond obtained at high pressure can be obtained by epitaxially growing high-purity diamond from a gas phase on a diamond Ib substrate by high-pressure synthesis. Further, as described in Patent Document 2, a diamond having only a low-angle grain boundary is obtained by using a plurality of diamond substrates or diamond grains oriented in the same crystal orientation and growing a single diamond on them. It has also been reported that

  However, a problem in synthesizing diamond by homoepitaxial growth is a method for removing and reusing a substrate. When obtaining an IIa diamond film by vapor phase synthesis using Ib diamond or the like as a substrate, it is necessary to remove the Ib diamond substrate from the grown diamond layer by some method. As a method for this, a method of separating the epitaxial film and the substrate or a method of eliminating the substrate at all can be considered. Since the diamond single crystal substrate is expensive, it is needless to say that the former method is preferable, and laser slicing is a typical method. However, the larger the diamond area, the thicker the diamond is needed for slicing and the worse the success rate.

  For this reason, when a single crystal diamond having a size of 1 cm × 1 cm is obtained, slicing is no longer difficult, and a method of removing the substrate must be used. This can be achieved by, for example, polishing using diamond abrasive grains as described in Patent Document 3 or a method of removing a layer reacted with an iron surface or an ion beam as described in Patent Document 4 Irradiation methods are known, but all of them require a long time. In addition, the inability to reuse a substrate by high pressure synthesis is a significant disadvantage in terms of cost.

Therefore, as disclosed in Patent Document 5 and Patent Document 6, an ion-implanted layer is formed in diamond, and the implanted layer is etched by an electrochemical method, whereby both the diamond substrate and the diamond layer sandwiching the implanted layer are damaged. A method of separating and peeling without problems was provided. However, in these prior arts, several MeV is selected as the implantation energy for forming the ion implantation layer. Therefore, an ion implantation machine for performing implantation of less than MeV, which is frequently used in the manufacturing process of silicon semiconductor devices. The so-called medium current machine cannot be used, and a high energy machine has to be used. Since the high energy machine has a small irradiation ion current amount, a high dose amount of 10 ¹⁶ ions / cm ² to 10 ¹⁷ ions / cm ² or more necessary for peeling is injected into a large area of about the size of a silicon wafer. The cost for making up a large part of the manufacturing cost of a large-area diamond single crystal has made it difficult to realize cost reduction.

JP 2007-270272 A Japanese Patent Laid-Open No. 3-75298 JP-A-2-26900 Japanese Patent Application Laid-Open No. 64-68484 JP 2005-272197 A JP 2008-031503 A

  As described above, according to the conventional technique, even when high-quality and large-area diamond is grown in a vapor phase, the cost for ion implantation is high because the cost of ion implantation is high. This has hindered widespread use due to the increased manufacturing cost of large-area vapor-phase synthetic diamond.

  An object of the present invention is to solve such problems of the prior art and provide a diamond peeling method that improves the ion implantation step required in the diamond peeling process and realizes peeling at a lower cost.

  The present inventors have made extensive studies to solve the above problems. As a result, in the ion implantation process for forming an ion implantation layer for separating these layers between the diamond layers, the present inventors formed the ion implantation layer by multistage implantation of implantation energy of 10 keV or more and less than 1 MeV and two or more stages. It has been found that a layer thickness of less than 0.0 μm may be formed. By forming the ion-implanted layer by such a method in the ion-implantation process, while obtaining the same effect as the high energy implantation of several MeV of the prior art, the medium current that is frequently used in the manufacturing process of silicon semiconductor devices It has been found that since an ion implanter can be used, the manufacturing cost of a large-area diamond single crystal can be greatly reduced.

In addition, the present inventors select carbon as an implantation species in the ion implantation, so that when the implantation species remain outside the non-diamond layer, the crystallinity, electrical properties, engineering properties, mechanical properties of the diamond that peels and separates. The effect on characteristics is small compared to other implanted species, and high quality can be realized. Further, after the ion implantation, a temperature of 650 ° C. or more and 950 ° C. or less in a vacuum of 10 ⁻² Pa or less or in an inert gas atmosphere. Thus, it has been found that if annealing is performed for 1 hour or more and 24 hours or less, the crystallinity of diamond on the implanted surface side is improved.

That is, the present invention has the following configuration.
(1) An ion implantation process for implanting ions into the main surface of the diamond substrate to form an ion implantation layer on the diamond substrate; and a diamond film is grown on the substrate surface on the side where the ion implantation layer is formed. However, the ion-implanted layer is electrochemically etched by applying a voltage by immersing the structure obtained by a process including a process including a process having a structure sandwiched between diamond layers in an etching solution. A diamond peeling method including a peeling step of separating the diamond layer,
In the ion implantation step, a diamond peeling method is characterized in that the ion implantation layer has an implantation energy of 10 keV or more and less than 1 MeV and a layer thickness of less than 9.0 μm by multistage implantation of two or more stages.
(2) The diamond peeling method according to (1) above, wherein the thickness of the ion-implanted layer is 0.1 μm or more.
(3) The method for peeling da diamond according to (1) or (2) above, wherein the ion species used for the ion implantation is carbon.
(4) The diamond substrate after the ion implantation is subjected to an annealing treatment at a temperature of 650 ° C. to 950 ° C. for 1 hour to 24 hours in a vacuum of 10 ⁻² Pa or less or in an inert gas atmosphere. The diamond peeling method according to any one of the above (1) to (3), which is characterized by the following.

  By using the diamond exfoliation method according to the present invention, a relatively inexpensive medium current ion implanter can be used without the need to perform expensive ion implantation with an implantation energy of several MeV, resulting in a large area and high quality gas phase synthesis. Diamond can be provided at low cost.

It is a figure which shows a diamond structure. It is a figure which shows an example of the peeling apparatus of a diamond structure. It is a figure which shows typically a mode that an ion implantation layer is etched.

  Hereinafter, preferred embodiments of a diamond peeling method according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are assigned to the same elements, and duplicate descriptions are omitted. Further, the dimensional ratios in the drawings do not necessarily match those described.

[Diamond structure]
FIG. 1 shows a diamond structure 01 made of diamond in the present invention (hereinafter, “diamond structure” is also simply referred to as “structure”). The structure 01 includes a diamond layer 02, a diamond layer 03, and an ion implantation layer 04. The diamond layers 02 and 03 may be single crystal or polycrystal, but single crystal diamond is more expensive, but is preferable because the effect of the present invention can be exhibited more greatly. The diamond layers 02 and 03 may be electrically conductive or insulating. However, since most diamonds used in industrial applications are insulative, there is usually an insulating property that is highly effective in the present invention. preferable. The conductivity is obtained in a state where boron (B) or phosphorus (P) is added to the diamond crystal.

  The ion implantation layer 04 can be formed by ion implantation from the main surface of the diamond layer 02 or 03. The diamond layers 02 and 03 that were originally integrated by ion implantation are divided into two layers by the formed ion implantation layer 04. The ion-implanted layer 04 is a layer in which the diamond structure is destroyed and graphitization proceeds and has conductivity. The depth and thickness from the main surface of the ion-implanted layer 04 to be formed mainly depend on the type of ion to be used, implantation energy, and irradiation amount. Therefore, these are determined and ion implantation is performed. The design of the ion implantation layer can be calculated and predicted almost accurately by a Monte Carlo simulation code such as the TRIM code.

In forming the ion implantation layer 04, the dose is adjusted so that the concentration of implanted atoms is 5 × 10 ¹⁸ / cm ³ or more and 5 × 10 ²¹ atoms / cm ³ or less. By setting it within this range, the conductivity of the ion-implanted layer 04 becomes sufficiently high. As a result, the diamond layers 02 and 03 can be separated and separated by electrochemical etching. When the implantation amount is less than 5 × 10 ¹⁸ / cm ³ , the conductivity cannot be sufficiently obtained, and the etching rate of electrochemical etching becomes extremely slow, which is not preferable. On the other hand, when the implantation amount is larger than 5 × 10 ²¹ pieces / cm ³ , damage to the crystal structure due to implantation cannot be ignored in the layer near the main surface of the diamond layer 02 or 03 selected as the implantation surface, and good crystallinity is obtained. This is not preferable because it cannot be maintained.

  The implantation energy is more preferably 10 keV or more and less than 1 MeV. By setting it to less than 1 MeV, a medium current ion implanter that is frequently used in the manufacturing process of silicon semiconductor devices can be used. Therefore, ion implantation can be performed at a low cost, resulting in a significant reduction in manufacturing cost. If it is less than 10 keV, the energy is low, and as a result, damage to the crystal structure in the layer near the injection surface becomes prominent, and good crystallinity cannot be maintained.

The thickness of the ion-implanted layer 04 to be formed is thinner than the conventional technique of several MeV if the implanted ion species and the irradiation dose are the same. If the thickness of the ion implantation layer is reduced, the etching rate at the time of electrochemical etching in the peeling step, which is a later step, is reduced. Therefore, the ion implantation layer is thickened by performing two or more stages of multi-stage ion implantation.
The layer thickness of the ion implantation layer 04 is preferably 0.1 μm or more and less than 9.0 μm. It is preferable that the thickness of the ion-implanted layer is 0.1 μm or more because the etching rate of electrochemical etching does not become extremely slow. Further, it is preferable that the ion implantation layer has a thickness of less than 9.0 μm because an implantation energy of 1 MeV or more is not required.
By setting the thickness of the ion implantation layer as described above, the thickness of the ion implantation layer 04 to be formed is kept at the same level as that of the prior art, and a medium current ion implanter is used so that it can be formed at a low cost. Can do.

  The purpose of forming the ion-implanted layer is to form a conductive layer by destroying the diamond structure and proceeding to graphitization, so the types of ions include carbon, boron, nitrogen, oxygen, phosphorus, Any element capable of ion implantation can be used, such as hydrogen, helium, aluminum, silicon, sulfur, and argon. Boron, phosphorus, and the like are frequently used in the manufacture of silicon devices, and since the irradiation current amount is large, a desired irradiation amount can be carried out in a short time, so that it can be suitably used. When carbon remains in diamond that is peeled and separated by ion implantation, it has the least impact on crystallinity, electrical properties, engineering properties, and mechanical properties, and can be used most favorably because it can achieve high quality. is there.

After ion implantation, annealing may be performed in vacuum or in an inert gas atmosphere for the purpose of improving the crystallinity of the diamond layer on the main surface side irradiated with ions. ^10-2 Pa or less can be suitably used in a vacuum, and a rare gas or nitrogen atmosphere can be suitably used in an inert gas. Other than this, there is a possibility that the crystallinity of the main surface irradiated with ions may be deteriorated. If the annealing temperature is 300 ° C. or higher and 1450 ° C. or lower, the effect of crystallinity recovery is seen, but more preferably 650 ° C. or higher and 950 ° C. or lower. If it is less than 300 ° C., the temperature is too low, so there is almost no effect of recovering crystallinity. On the other hand, if the temperature is higher than 1450 ° C., the crystallinity deteriorates, which is not suitable. The annealing time is preferably 1 hour or more and 24 hours or less. If it is this range, the effect of crystallinity recovery will appear. If it is less than 1 hour, the crystallinity is hardly recovered, and if it is longer than 24 hours, the crystallinity is worsened.

The diamond structure in the present invention can be produced, for example, as follows.
First, a diamond substrate is prepared. Next, ions such as carbon, boron, and phosphorus are implanted from the main surface of the substrate to form an ion implantation layer on the diamond substrate. A diamond film is formed on the substrate surface on the side where the ion implantation layer is formed. Thereby, a diamond structure having a structure in which the ion implantation layer 04 is sandwiched between the diamond substrate (diamond layer 03) and the diamond film (diamond layer 02) can be obtained.

  The diamond layers 02 and 03 may include diamond that has been vapor-phase grown after the ion implantation layer 04 is formed. In the case of crystal growth on the main surface irradiated with ions, after the annealing, the crystallinity of the main surface is improved, so that higher quality diamond is vapor grown. A structure in which a plurality of diamond layers and ion-implanted layers are alternately formed is also included in the structure referred to in the present invention. In order to enable etching by an electrochemical method, the ion implantation layer 04 of the structure referred to in the present invention is at least partly disposed in the etching solution, preferably the entire periphery is in contact with the etching solution. Need to be.

[Peeling device]
FIG. 2 is a diagram showing an example of a peeling apparatus for carrying out the diamond peeling method of the present invention. The peeling apparatus 11 includes an etching solution 12, an etching tank 13, and an electrode 14. As the etching solution 12, pure water is used. The etching tank 13 uses a beaker using borosilicate glass, but is not particularly limited as long as it is a container that can hold pure water. The electrode 14 uses an electrode such as platinum or graphite at the liquid contact portion.

  In the peeling apparatus 11 having the above configuration, the structure 01 is disposed between the electrodes 14 and 14 in the etching solution 12, and a voltage is applied between the electrodes 14 and 14 to etch the ion implantation layer 04 and diamond. Separation and separation of the layer 02 and the diamond layer 03 are performed. FIG. 3 is a schematic view showing how the ion implantation layer 04 is etched. Although the voltage depends on the distance between the electrodes, it is preferable to set the voltage so that an electric field of 100 V / cm to 300 V / cm is applied between the electrodes.

  In the ion implantation for peeling and separating diamond, the energy of several MeV has been used so far despite the high cost. The reason is that the formed ion implantation layer is thick and the vicinity of the implantation surface. This is because there is little crystal damage such as vacancies and dislocation entering the layered diamond, so that relatively high quality diamond can be peeled off in a relatively short time. On the other hand, when the energy is less than MeV, the ion-implanted layer formed is relatively thin as compared with several MeV, and the crystal damage in the layer near the implanted surface is large.

The inventors of the present invention studied ion implantation below MeV, paying attention to the fact that it can be carried out at a low cost. The first problem with implantation of less than MeV is that vacancies tend to enter the crystal structure in the vicinity of the implantation surface as compared to several MeV implantation, and therefore, it may not be diamond even after peeling. Therefore, the crystallinity of the exfoliated diamond is judged by whether or not diamond is epitaxially grown on the main surface after ion implantation, and the relationship between crystal damage and epitaxial growth in the vicinity of the implanted surface is quantitatively investigated. It was. As a result, even if the implantation energy is less than MeV, the vacancy density in the vicinity of the implantation surface calculated by ion implantation simulation (TRIM code) by the Monte Carlo method is higher by about one digit or more than several MeV implantation 6.0 × 10. It has been found that epitaxial growth is possible even at ²³ cm ⁻² , and it has been found that implantation of less than MeV is also applicable from the viewpoint of deterioration of crystallinity near the implantation surface.

Next, a method for making the thickness of the ion implantation layer comparable to that of several MeV implantation by implantation less than MeV was searched. The thickness of the layer formed by one MeV injection is about 0.1 μm or more. On the other hand, when the implantation is less than MeV, the thickness of the formed layer is several tens of nm, so that the electrochemical etching time becomes extremely long. I examined ion implantation layer formation experiment and simulation by TRIM code, it was decided by the density of vacancies introduced by ion implantation whether it would be modified into a graphitized conductive layer by ion implantation or left as diamond layer, The hole threshold density was found to be 1.1 × 10 ²³ cm ⁻³ . As a result, it is formed by multi-stage ion implantation of two or more stages so that the thickness of the pore density becomes 1.1 × 10 ²³ cm ⁻³ or more by implantation less than MeV becomes 0.1 μm or more and less than 9.0 μm. This is what I came up with.

Thus, in the simulation using the TRIM code, the surface vacancy density generated by ion implantation is 6.0 × 10 ²³ cm ⁻² or less, and the vacancy density in the ion implantation region is 1.1 × 10 ²³ cm ⁻³ or more. It has been found that if two or more stages of multi-stage ion implantation are performed so that the thickness becomes 0.1 μm or more, implantation energy less than MeV can be used. Correspondingly, it has been found that an ion implantation layer is formed by multi-stage implantation with an implantation energy of 10 keV or more and less than 1 MeV and two or more stages, and the layer thickness is made 0.1 μm or more and less than 9.0 μm. It is. The above conditions are technically not limited to the injection of less than MeV except the viewpoint of cost, and can be applied to the injection of MeV or more. As a result of increasing the thickness of the ion implantation layer by performing multi-stage implantation with an energy of MeV or higher, the electrochemical etching time of the ion implantation layer can be further shortened.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
[Example 1]
First, a sample a was manufactured as the structure 01 shown in FIG. 1 as follows.
An Ib high-temperature high-pressure diamond single crystal substrate is prepared. After ion implantation from the main surface, CVD diamond is epitaxially grown on the implantation surface, and diamond deposited around the ion implantation layer on the side surface of the substrate is removed by laser cutting. Was made.
The size of the main surface is 4 × 4 mm, the diamond layer 02 is a high-temperature high-pressure synthetic Ib diamond single crystal having a thickness of 0.4 mm, and the diamond layer 03 is a thickness including a high-temperature high-pressure synthetic Ib diamond single crystal having a thickness of 0.26 μm. It was a 0.37 mm thick CVD diamond single crystal.
The ion-implanted layer 04 in which graphitization has progressed is performed at a high temperature and a high pressure by implanting C ⁺ ions at an energy of 350 keV and 280 keV and a dose of 1.2 × 10 ¹⁶ ions / cm ² and 4 × 10 ¹⁵ ions / cm ² , respectively. It is formed by two-stage implantation from the main surface of the synthetic Ib diamond single crystal, the thickness is 0.14 μm from the depth of 0.26 μm to 0.38 μm from the implantation surface, and the implanted atom concentration is estimated by simulation calculation. 1.4 × 10 ²⁰ cm ⁻³ to 2.2 × 10 ²¹ cm ⁻³ . The diamond layers 02 and 03 were insulative and the ion implantation layer 04 was electrically conductive.

Next, a diamond peeling apparatus 11 shown in FIG. 2 was prepared. The etching solution 12 was pure water, the etching tank 13 was a beaker made of borosilicate glass, and the electrode 14 was a platinum electrode.
And the electrode a of the peeling apparatus 11 was set to about 1 cm, and the sample a was placed between the electrodes in the etching solution. When a voltage of 340 V was applied between the electrodes and allowed to stand, the ion implantation layer 04 was completely etched in 13 hours, and the diamond layers 02 and 03 were separated and separated.

As a sample b, a structure 01 was produced in the same manner as the sample a except that a step of performing annealing at a temperature of 650 ° C. for 24 hours in a vacuum of 1 × 10 ⁻⁴ Pa immediately after ion implantation was added. The crystallinity of CVD diamond epitaxially grown on the implantation surface was found to be better than that of sample a by rocking curve measurement. Thereafter, in the peeling apparatus 11, peeling / separation was tried under the same conditions as those for the sample a. As a result, the ion implantation layer 04 was completely etched in 13 hours, and the diamond layers 02 and 03 were separated and separated.

[Example 2]
First, a sample c was manufactured as the structure 01 shown in FIG. 1 as follows.
An Ib high-temperature high-pressure diamond single crystal substrate is prepared, and after implanting ions from the main surface, CVD diamond is epitaxially grown on the implanted surface, and the diamond deposited around the ion-implanted layer on the side surface of the substrate is removed by laser cutting. Was made.
The size of the main surface is 4 × 4 mm, the diamond layer 02 is a high-temperature high-pressure synthetic Ib diamond single crystal having a thickness of 0.4 mm, and the diamond layer 03 is a thickness including a high-temperature high-pressure synthetic Ib diamond single crystal having a thickness of 0.23 μm. It was a 0.37 mm thick CVD diamond single crystal.
In the ion-implanted layer 04 in which graphitization has progressed, B ⁺ ions are implanted at an energy of 350 keV, 270 keV, and 200 keV, and the irradiation doses are 1.2 × 10 ¹⁶ ions / cm ² and 6.0 × 10 ¹⁵ ions / cm ^{2, respectively.} And 6.0 × 10 ¹⁵ ions / cm ² are formed by three-stage implantation from the main surface of the high-temperature, high-pressure synthetic Ib diamond single crystal, and the thickness is 0.23 μm to 0.43 μm deep from the implantation surface. At 0.20 μm, the implanted atom concentration was measured by SIMS, and was consistent with the simulation calculation between 2.0 × 10 ²⁰ cm ⁻³ and 2.0 × 10 ²¹ cm ⁻³ . The diamond layers 02 and 03 were insulative and the ion implantation layer 04 was electrically conductive.

Next, a diamond peeling apparatus 11 shown in FIG. 2 was prepared. The etching solution 12 was pure water, the etching tank 13 was a beaker made of borosilicate glass, and the electrode 14 was a platinum electrode.
And the electrode c of the peeling apparatus 11 was set to about 1 cm, and the sample c was placed between the electrodes in the etching solution. When a voltage of 340 V was applied between the electrodes and allowed to stand, the ion implantation layer 04 was completely etched in 10 hours, and the diamond layers 02 and 03 were separated and separated.

As a sample d, a structure 01 was fabricated in the same manner as the sample c except that a step of performing annealing at a temperature of 950 ° C. for 1 hour in a vacuum of 1 × 10 ⁻⁵ Pa immediately after ion implantation was added. The crystallinity of CVD diamond epitaxially grown on the implantation surface was found to be better than that of sample c by rocking curve measurement. Thereafter, in the peeling apparatus 11, peeling / separation was attempted under the same conditions as those for the sample c. As a result, the ion implantation layer 04 was completely etched in 9 hours, and the diamond layers 02 and 03 were peeled off and separated.

[Comparative Example 1]
First, a sample e was produced as the structure 01 shown in FIG. 1 as follows.
An Ib high-temperature high-pressure diamond single crystal substrate is prepared. After ion implantation from the main surface, CVD diamond is epitaxially grown on the implantation surface, and diamond deposited around the ion implantation layer on the side surface of the substrate is removed by laser cutting. Was made.
The size of the main surface is 4 × 4 mm, the diamond layer 02 is a high-temperature high-pressure synthetic Ib diamond single crystal having a thickness of 0.4 mm, and the diamond layer 03 is a thickness including a high-temperature high-pressure synthetic Ib diamond single crystal having a thickness of 0.21 μm. It was a 0.37 mm thick CVD diamond single crystal.
The ion-implanted layer 04 having undergone graphitization is implanted in a single step from the main surface of the high-temperature high-pressure synthetic Ib diamond single crystal with B ⁺ ions implanted at an energy of 175 keV and an irradiation dose of 1.0 × 10 ¹⁶ ions / cm ^2. The thickness is 0.03 μm from the depth 0.21 μm to 0.24 μm from the implantation surface, and the implanted atom concentration is 4.0 × 10 ²⁰ cm ⁻³ to 1.2 × 10 ^{21 as} measured by SIMS. It was consistent with the simulation calculation between cm ⁻³ . The diamond layers 02 and 03 were insulative and the ion implantation layer 04 was electrically conductive.

Next, a diamond peeling apparatus 11 shown in FIG. 2 was prepared. The etching solution 12 was pure water, the etching tank 13 was a beaker made of borosilicate glass, and the electrode 14 was a platinum electrode.
And the electrode e of the peeling apparatus 11 was set to about 1 cm, and the sample e was placed between the electrodes in the etching solution. Although a voltage of 340 V was applied between the electrodes and left to stand, the ion-implanted layer 04 was not completely etched even after 48 hours (2 days), and the diamond layers 02 and 03 were not separated or separated.

DESCRIPTION OF SYMBOLS 01 Diamond structure 02 Diamond layer 03 Diamond layer 04 Ion implantation layer 11 Diamond peeling apparatus 12 Etching solution 13 Etching tank 14 Electrode

Claims (4)

An ion implantation step of implanting ions into the main surface of the diamond substrate to form an ion implantation layer on the diamond substrate, and growing a diamond film on the substrate surface on the side where the ion implantation layer is formed, the ion implantation layer, The diamond structure obtained by the process including the process of forming a diamond structure having a structure sandwiched between diamond layers is immersed in an etching solution, and a voltage is applied to etch the ion implantation layer electrochemically. Thus, a diamond peeling method including a peeling step of separating a diamond substrate and a diamond layer,
In the ion implantation step, an ion implantation layer having a layer thickness of less than 9.0 μm is formed by performing ion implantation at two or more stages with different implantation energy within a range of implantation energy of 10 keV or more and less than 1 MeV. And diamond peeling method. The diamond peeling method according to claim 1, wherein a thickness of the ion implantation layer is 0.1 μm or more.   The method for stripping diamond according to claim 1 or 2, wherein the ion species used for the ion implantation is carbon. The diamond substrate after the ion implantation is subjected to an annealing treatment at a temperature of 650 ° C. to 950 ° C. for 1 hour to 24 hours in a vacuum of 10 ⁻² Pa or less or in an inert gas atmosphere. The diamond peeling method according to any one of claims 1 to 3.

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