JP2015067517A - Method for manufacturing single crystal diamond - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single crystal diamond substrate, which is obtained by using a plurality of single crystal diamond substrates as raw materials and joining them on the side surfaces thereof having a length of more than 20 mm.SOLUTION: The method for manufacturing a single crystal diamond substrate comprises the following steps of: (1) placing a plurality of single crystal diamond seed substrates having the same crystallographic properties, the outer peripheral side surface of the main growth surface of the seed substrate shaped so that an angle between a ridge line and off direction of the seed substrate is the same among the seed substrates and the ridge line having a length of more than 20 mm on the shaped side surface, in such a state that both side surfaces of the shaped seed substrates in the longitudinal direction are contacted to each other on a support, the off directions of the seed substrates are coincident respectively and the main growth surfaces of the seed substrates are exposed; and (2) growing a single crystal diamond on the main growth surfaces of the plurality of seed substrates placed on the support in the (1) step to join the plurality of seed substrates.

Description

  The present invention relates to a method for producing single crystal diamond.

  Diamond having excellent characteristics as a semiconductor is expected as a material for semiconductor devices such as high-frequency / high-power devices and light-receiving devices. In particular, in order to put diamond to practical use as a semiconductor material, a wafer composed of a large area of homogeneous single crystal diamond is required.

  Conventionally, single crystal diamond is grown mainly by a method such as a high pressure synthesis method or a gas phase synthesis method. Among these methods, the high-pressure synthesis method is limited to the production of a substrate having an area of about 1 cm square, and cannot be expected as a method for producing a single crystal substrate having an area larger than this. In addition, it is difficult to obtain a single crystal diamond substrate having an area of about 5 mm square or more, and it is not easy to enlarge the area.

  For this reason, as a method for producing a large-area single crystal diamond, a diamond crystal is grown on a plurality of diamond crystals arranged on the same surface by a vapor phase method and bonded to form a large diamond crystal. A technique for producing mosaic diamond has been developed (Non-patent Document 1).

  When manufacturing mosaic diamond, there are cases where only single crystal diamond is used as the base material to be joined, and there are cases where single crystal diamond and polycrystalline diamond or other materials are used. The diamond as the base material is bonded to the base material by growing the diamond by a vapor phase method.

  Among these methods, only a single crystal diamond substrate is used and bonded to obtain a large single crystal diamond. For example, a gap between single crystal diamond substrates to be bonded and a difference in height are predetermined. A method for producing a large diamond crystal by suppressing the generation of abnormally grown particles growing at the boundary between the substrate by vapor-phase-growing an integral diamond crystal on the substrate is reported. (Patent Document 1).

  Furthermore, the off-angle and off-direction of the single crystal diamond used as the base material are appropriately selected, and a plurality of the single crystal diamonds are arranged side by side, and then the diamond is preferentially arranged in the direction of the adjacent single crystal by the vapor phase synthesis method. A method of enlarging crystals and promoting bonding has also been proposed (Patent Document 2).

  Furthermore, a method using a cleaved surface as a side surface to be joined, a method of providing an angle on the side surface to be joined, and the like are also known (Patent Documents 3 and 4).

  By the way, a method of growing single crystal diamond on a diamond substrate by homoepitaxial growth using a vapor phase synthesis method is applied to, for example, synthesis of semiconductor-grade high-quality diamond. However, in the epitaxial growth of diamond by the vapor phase synthesis method, defects such as a large number of abnormally grown particles and growth hills are likely to occur, and it is not easy to synthesize large-area single crystal diamond.

  Similarly, defects on the surface of the substrate are inherited by the growth layer, and it is impossible to control the position of each substrate for each substrate, which is one of the causes that hinder the unification of the properties of the growth layer. Furthermore, it is known that the properties of the growth layer are affected by strain existing in the substrate before growth (Non-patent Document 2).

  Usually, in the method of producing a mosaic diamond by growing diamond crystals on a plurality of diamond crystals by a vapor phase method, the threshold for considering the off angles of the diamond substrates to be joined to be the same is at least 1 degree or more. Yes. However, if the off-angle is different even once, the quality of the growth layer will be different under the same conditions, and on the mosaic substrate bonded by this method, single crystal layers having different qualities for each bonded single crystal region are present. Will grow. In addition, there is a similar problem in the method (Patent Document 2) in which a mosaic substrate is manufactured by actively using substrates having different crystal plane directions such as the off angle and the off direction described above.

  In addition, when diamond is used as a material for a semiconductor device, usually, impurities are intentionally added to grow diamond on a substrate (diamond wafer). It is known that the change in crystallinity accompanying this depends on the properties of the substrate (Non-patent Document 3). Therefore, even if a diamond wafer having a large area is obtained by using the above-described method, if the wafer has non-uniform crystal plane direction such as off-angle and off-direction, strain and defect distribution, etc. The fabricated device is expected to have non-uniform characteristics. Therefore, it is clear that even when a mosaic wafer having such properties is used as a substrate, the rate at which devices that can effectively withstand use are taken out is extremely low. Furthermore, the mosaic diamond substrate needs to have strength so that it can withstand the processing for device fabrication, and thus it may be necessary to further pile up after joining. Even in this case, if the properties of the single crystal diamond used as the base material to be joined are different, it becomes difficult to accumulate uniformly.

  Due to the above difficulties, it is difficult for the conventional mosaic diamond substrate to suppress abnormal growth along the bonding boundary, and the boundary is not smoothly bonded. Disruption is disclosed (Non-patent Document 1), and the crystallinity is poor without being measured.

  As a method of manufacturing a large-area diamond substrate for the purpose of solving such problems, a method using a self-supporting film manufacturing method using ion implantation is known (Patent Document 5). If such a method is used, it is expected that substrates having the same off angle and off direction can be easily joined together.

  However, although it is described in this document that the off directions between a plurality of single crystal diamonds coincide with each other, there is no description about the off direction of each single crystal diamond.

  For example, although the method described in Patent Document 5 is excellent as a method for manufacturing a large-area diamond substrate, if the relationship between the off-direction directions is not appropriate between the substrates to be bonded, the obtained single crystal diamond substrate It is difficult to say that the portion corresponding to the joining region is completely smoothly covered, and there is a problem that the practicality is poor. Patent Document 6 discloses a manufacturing method in which the angles formed by the plane orientations are aligned within 5 degrees. However, in actuality, for example, as described in Patent Document 4, the relationship between the off-directions of substrates to be bonded is disclosed. If it is shifted by 5 degrees, the covering area is not completely covered. In such a case, it becomes difficult to carry out a processing process such as polishing, and it becomes difficult to use it as a semiconductor wafer.

JP 7-48198 A JP 2006-306701 A Japanese Patent Publication No. 6-53638 EP0687747A1 JP 2010-150069 A Japanese Patent No. 2654232

Meguro, Nishibayashi, Imai, SEI Technical Review 163, 53 (2003). P. S. Weiser, S.M. Prawer, K.M. W. Nugent, A.M. A. Bettiol, L.M. I. Kostidis, D.C. N. Jamison, Diamond and Related Materials 5 (1996), 272-275. K. Arima, H .; Miyatake, T .; Teraji, and T.A. Ito, Journal of Crystal Growth 309 (2007), 145-152. Hideaki Yamada, Akiyoshi Chayahara, Yoshiki Mokuno, Nobuteru Tsubuchi, Shin-ichi Shikata, Diamond and Related Materials, Volume 33, Volume 33, Volume 33

  From the background art as described above, a large area substrate made of single-crystal diamond is highly demanded, but even with a mosaic diamond substrate using bonding, the bonding region has a length exceeding 20 mm. There is no report on a method of bonding single crystal diamond having a seed substrate and bonding them.

  As a result of intensive studies to achieve such an object, the present inventor is a plurality of single crystal diamond seed substrates having the same crystallographic properties, which are materials for producing single crystal diamond, The angle between the seed substrate ridge line between each seed substrate and the off direction of the seed substrate is adjusted, the outer peripheral side surface of the main growth surface of the seed substrate is shaped, and the ridge line is based on the shaped side surface A plurality of seed substrates having a length of more than 20 mm, the side surfaces in the length direction of the seed substrates that have been shaped are in contact with each other on a support base, and the off-directions of the respective seed substrates are matched, and the By placing the seed substrate so that the main growth surface of the seed substrate is exposed, it has become possible to produce single crystal diamond by joining the seed substrates having a joint portion exceeding 20 mm.

  The present invention has been completed based on such findings, and broadly encompasses the inventions of the embodiments shown below.

Item 1 A method for producing a single crystal diamond substrate comprising the following steps:
(1) A plurality of single crystal diamond seed substrates having the same crystallographic properties, and the angles formed by the ridgelines of the seed substrate and the off direction of the seed substrate are all the same between the seed substrates. In addition, a plurality of single crystal diamond seed substrates on which the outer peripheral side surface of the main growth surface of the seed substrate is shaped and the length of the ridge line based on the shaped side surface exceeds 20 mm are shaped on the support base. A step of placing the seed substrates in such a manner that the side surfaces in the length direction of the seed substrates are in contact with each other, the off-directions of the seed substrates are matched, and the main growth surface of the seed substrate is exposed;
(2) A step of growing single crystal diamond on a main growth surface of a plurality of seed substrates placed on a support table in the step (1) and bonding the plurality of seed substrates.

  Item 2 The main growth surface of the seed substrate so that the angle formed by the ridgelines of the single crystal diamond seed substrate having the same crystallographic properties in the step (1) and the off direction of the seed substrate is less than 90 degrees Item 2. The method for producing a single crystal diamond substrate according to Item 1, wherein the outer peripheral side surface of the substrate is shaped.

  Item 3 The main growth surface of the seed substrate so that the angle formed by the ridgelines of the single crystal diamond seed substrate having the same crystallographic properties in the step (1) and the off direction of the seed substrate is 18 degrees or more. Item 3. The method for producing a single crystal diamond substrate according to Item 1 or 2, wherein the outer peripheral side surface of the substrate is shaped.

  Item 4 The method for producing a single crystal diamond substrate according to any one of Items 1 to 3, wherein the same crystallographic property is an off direction and / or an off angle.

  Item 5 A single crystal diamond substrate obtained by the method according to any one of Items 1 to 4.

  Although the effect which the single-crystal diamond manufacturing method of this invention exhibits below is explained in full detail below, it cannot be overemphasized that this invention is not limited to the invention which has all the following effects.

  According to the production method of the present invention, even when a plurality of single crystal diamond crystals are used as seed substrates, even when the bonding sites exceed 20 mm, they can be bonded, and a diamond having a larger area can be bonded. Crystal substrates can be manufactured.

  According to the manufacturing method of the present invention, it becomes possible to enlarge the area of the substrate as compared with the conventional method, and it is possible to increase the number of tools, window materials, electronic elements, etc. manufactured from one substrate, so that it is manufactured at low cost. Is possible.

Method for Manufacturing Single Crystal Diamond Substrate A method for manufacturing a single crystal diamond substrate according to the present invention includes the following Step 1 and Step 2.

(1) A plurality of single crystal diamond seed substrates having the same crystallographic properties, and the angles formed by the ridgelines of the seed substrate and the off direction of the seed substrate are all the same between the seed substrates. In addition, a plurality of single crystal diamond seed substrates on which the outer peripheral side surface of the main growth surface of the seed substrate is shaped and the length of the ridge line based on the shaped side surface exceeds 20 mm are shaped on the support base. A step of placing the seed substrates in such a manner that the side surfaces in the length direction of the seed substrates are in contact with each other, the off-directions of the seed substrates are matched, and the main growth surface of the seed substrate is exposed;

(2) A step of growing single crystal diamond on a main growth surface of a plurality of seed substrates placed on a support table in the step (1) and bonding the plurality of seed substrates.

<About Step 1>
Step 1 in the method for producing a single crystal diamond substrate according to the present invention includes a plurality of single crystal diamond seed substrates having the same crystallographic properties, wherein an angle formed between the ridge line of the seed substrate and the off direction of the seed substrate However, the outer peripheral side surface of the main growth surface of the seed substrate is shaped so that all of the seed substrates are the same, and the length of the ridge line based on the shaped side surface exceeds 20 mm. The crystal diamond seed substrate is placed on a support base, the side surfaces in the length direction of the shaped seed substrate are in contact with each other, the off directions of the seed substrates are aligned, and the main growth surface of the seed substrate is It is a process of mounting so that it may be in an exposed state. Below, the said process 1 is explained in full detail.

[Multiple single crystal diamond seed substrates having the same crystallographic properties]
The method for obtaining a plurality of single crystal diamond seed substrates having the same crystallographic properties is not particularly limited, and is it possible to select a plurality of single crystal diamond substrates having the same crystallographic properties from commercially available single crystal diamond substrates? Any known diamond production method may be employed as appropriate to produce a single crystal diamond substrate having the same crystallographic properties, and is not particularly limited.

  For example, as a method for obtaining a plurality of single crystal diamond substrates having the same crystallographic properties, a clone substrate manufacturing technique shown below can be cited. This manufacturing technique is a process in which a non-diamond layer is formed by ion implantation near the surface of a diamond single crystal parent substrate, and then the non-diamond layer is etched to separate a single-crystal diamond layer above the non-diamond layer. This is a technique for obtaining a sub board. Specifically, descriptions in Japanese Patent No. 4340881, Japanese Patent Application Laid-Open No. 2007-112737, WO 2011/074599, Japanese Patent Application Laid-Open No. 2010-150069, and the like may be referred to.

  Since the child substrate obtained by this technique has the same crystallographic properties as the parent substrate, it has the same crystallographic properties by repeatedly adopting the above steps for the same parent substrate. A plurality of child boards, that is, clone boards can be obtained efficiently.

  Such a plurality of sub-substrates (clone substrates) may be a plurality of single-crystal diamond seed substrates having the same crystallographic properties in the production method of the present invention.

  The crystallographic properties include, for example, crystal plane directions such as off angle and off direction; strain, defect distribution, and the like. The off angle and / or the off direction are preferable.

[Shaping of the outer peripheral side of the main growth surface of the seed substrate]
In the plurality of single crystal diamond seed substrates, the outer peripheral side surfaces of the main growth surfaces of the seed substrates are shaped so as to be the same between the seed substrates. Here, the term “same” means that an angle deviation of about 2 degrees is an allowable range.

  The main growth surface of the seed substrate described above can be understood as the surface having the largest area in such a seed substrate. Alternatively, when the single crystal diamond is grown by a method such as a vapor phase synthesis method, a surface in contact with the discharge region may be a main growth surface. For example, a plurality of single crystal diamond seed substrates obtained by the method for producing a clone substrate exemplified in [Acquisition of multiple single crystal diamond seed substrates having the same crystallographic properties] are separated from the parent substrate. Or the opposite face.

  The above-described outer peripheral side surface is a surface other than the above-described main growth surface or the opposite surface, and a plurality of the outer peripheral side surfaces may exist. The outer peripheral side surface used for shaping may be at least one of these surfaces.

  The above-mentioned ridge line means an intersection line between the side surface obtained by subjecting the outer peripheral side surface of the main growth surface to the shaping process and the main growth surface or the opposite surface.

  The length of the ridge line based on the shaped outer peripheral side surface exceeds 20 mm. Moreover, such an outer peripheral side surface may be called the outer peripheral side surface of a length direction.

  The angle formed between the off direction of the seed substrate and the ridge line of the seed substrate is not particularly limited, but it may be usually less than 90 degrees. This is because when the angle is 90 degrees, a plurality of seed substrates cannot be bonded at a bonding surface exceeding 20 mm.

  Further, the lower limit value of the angle is not particularly limited, but is usually set to 0 degree or more, and preferably 18 degrees or more.

  When the angle between the off direction of the seed substrate and the ridge line of the seed substrate is 90 degrees to 180 degrees, the angle is defined as the catch angle in the present invention. In addition, even if the angle prescribed | regulated by this invention converted in this way exceeds a negative angle or 180 degree | times, it cannot be overemphasized that this is converted between 0 degree | times and 90 degree | times.

  The shaping method specifically provided is not particularly limited, and examples thereof include a method employing a polishing process such as Skyf polishing or a cutting process such as laser cutting.

  As will be described later, the plurality of seed substrates having the same crystallographic properties described above are placed so that the side surfaces in the longitudinal direction of the seed substrate are in contact with each other. It is preferably shaped by polishing or the like so as to be substantially flat.

  Further, the side surfaces in the length direction of the seed substrate are in contact with each other between the off direction of the plurality of seed substrates having the same crystallographic properties and the outer peripheral side surface subjected to the shaping process, as described later. As long as the off-directions of the substrates coincide with each other, the main growth surface of the seed substrate or the opposite surface thereof and the outer peripheral side surface obtained by shaping are not necessarily in a vertical relationship, For example, the angle formed by the two may have an angle of about 45 degrees to 135 degrees.

  In addition, when adopting a plurality of seed substrates having the same crystallographic properties as described above, a child substrate obtained by a clone substrate production technique as described above, the outer peripheral side surface is appropriately shaped by the method described above, A clone substrate produced using this as a parent substrate can be used as a plurality of seed substrates having the same crystallographic properties after the shaping process of the present invention.

  In this case, it is necessary to shape the outer peripheral side surfaces of the main growth surface of the parent substrate so that at least the distance between the pair of facing surfaces is constant. For example, at least the pair of facing surfaces are parallel to each other. It is preferable to be formed into a shape.

  Further, the thicknesses of the plurality of seed substrates may be the same or different. The thickness can be obtained by appropriately employing the above-described clone substrate acquisition technique. Alternatively, the thickness can be appropriately adjusted by polishing.

  It should be noted that the thickness of the seed substrate is not necessarily the same for all the seed substrates, and may be regarded as the same if the difference in thickness is within a range of about 20 μm or less. it can.

[Placing multiple seed substrates on a support stand]
In step 1 in the manufacturing method of the present invention, the plurality of seed substrates described above whose outer peripheral side surfaces of the main growth surface are shaped are placed on the support base, and the lengthwise side surfaces of the seed substrates that have been shaped with respect to each other. Are placed so that the crystal plane of the seed substrate is aligned with the off direction, and the main growth surface of the seed substrate is exposed.

  In addition, in the above-mentioned shaped single crystal diamond seed substrate, when having a side surface parallel to the shaped outer peripheral side surface, the parallel side surfaces or the shaped outer peripheral side surface, A side surface parallel to the side surface may be contacted.

<About step 2>
In step 2 of the manufacturing method according to the present invention, single crystal diamond is grown on the main growth surfaces of the plurality of seed substrates placed on the support base in the step (1), and the plurality of seed substrates are joined. It is a process.

  By this process, the plurality of diamond seed substrates are bonded. In addition, a diamond crystal layer of about 100 to 1000 μm may be further formed on the bonded seed substrate. The crystallographic properties of such a layer are the same as the crystallographic properties of the plurality of seed substrates.

  The method for growing the single crystal diamond is not particularly limited, and examples thereof include a vapor phase synthesis method. The vapor phase synthesis method is not particularly limited, and for example, a known method such as a microwave plasma CVD method, a hot filament method, a direct current discharge method, or the like can be applied.

  In particular, according to the microwave plasma CVD method, a high-purity diamond single crystal film can be grown. Specific manufacturing conditions are not particularly limited, and a diamond single crystal may be grown according to known conditions. As the source gas, for example, a mixed gas of methane gas and hydrogen gas can be used. As an example of specific diamond growth conditions, in a mixed gas of hydrogen and methane used as a reaction gas, methane is supplied at a ratio of about 0.01 to 0.33 mol with respect to 1 mol of hydrogen supply. It is preferable to do. Moreover, what is necessary is just to usually set the pressure in a plasma CVD apparatus to about 13.3-40 kPa. As the microwave, a microwave having a frequency permitted for industrial and scientific use such as 2.45 GHz and 915 MHz is usually used. The microwave power is not particularly limited, but is usually about 0.5 to 5 kW. Within such a range, for example, each condition may be set so that the temperature of the substrate (single crystal diamond substrate) is about 900 to 1300 ° C., preferably about 900 to 1100 ° C.

Single crystal diamond substrate The diamond substrate produced by the method of the present invention has uniform crystallographic properties. The crystallographic properties are as described above.

  In addition, the single crystal diamond substrate manufactured by the method of the present invention is subjected to the above-described method and the outer peripheral side surface of the main growth surface is subjected to a molding process or the like to manufacture the above-described single crystal diamond substrate of the present invention. Considering a plurality of seed substrates in the method, a single crystal diamond having a larger area can be easily formed as appropriate.

  Examples for explaining the present invention in more detail are shown below. However, it goes without saying that the present invention is not limited to the description of the examples.

[Example 1]
For two amorphous single crystal diamond (100) substrates having the same crystallographic properties and having a width of about 15 mm and a length of about 34 mm and a thickness of 0.4 mm, the off-direction is evaluated using X-ray diffraction, It was confirmed that the off direction had an angle of 60 degrees with respect to the ridge line in the length direction.

  Next, these single crystal diamond substrates are placed in a commercially available microwave plasma CVD apparatus so that the lengthwise sides are in contact with each other so that the off-directions of these single crystal diamond substrates are aligned. Using the apparatus, the microwave power is 10 kW, A single crystal diamond film was grown for 17 hours on the ion-implanted surface of the seed crystal at a gas pressure of 10 kPa, a hydrogen gas flow rate of 1 slm, and a methane gas flow rate of 0.01 slm. The substrate temperature at the end of the growth of single crystal diamond was 1200 ° C. The formed single crystal diamond film had a thickness of 0.2 mm.

  After the growth, these diamond substrates were integrated, and the contact portions were uniformly covered with single crystal diamond.

[Example 2]
For two rectangular single crystal diamond (100) substrates having the same crystallographic properties, width 20 mm, length 40 mm, and thickness 0.2 mm, the off direction is evaluated using X-ray diffraction, and the length direction It was confirmed that the off direction had an angle of 88 degrees with respect to the ridgeline.

  Next, these single crystal diamond substrates are placed in a commercially available microwave plasma CVD apparatus so that the lengthwise sides are in contact with each other so that the off-directions of these single crystal diamond substrates are aligned. Using the apparatus, the microwave power is 10 kW, A single crystal diamond film was grown for 14 hours on the ion-implanted surface of the seed crystal at a gas pressure of 13 kPa, a hydrogen gas flow rate of 1 slm, and a methane gas flow rate of 0.01 slm. The substrate temperature at the end of the growth of single crystal diamond was 1200 ° C. The formed single crystal diamond film had a thickness of 0.2 mm.

  After the growth, these diamond substrates were integrated, and the contact portions were uniformly covered with single crystal diamond.

[Example 3]
For two amorphous single crystal diamond (100) substrates having the same crystallographic properties and having a width of about 15 mm and a length of about 23 mm and a thickness of 0.5 mm, the off direction is evaluated using X-ray diffraction, It was confirmed that the off direction had an angle of 45 degrees with respect to the ridge line in the length direction.

  Next, these single crystal diamond substrates are placed in a commercially available microwave plasma CVD apparatus so that the lengthwise sides are in contact with each other so that the off-directions of these single crystal diamond substrates are aligned. Using the apparatus, the microwave power is 10 kW, A single crystal diamond film was grown for 16 hours on the ion-implanted surface of the seed crystal at a gas pressure of 13 kPa, a hydrogen gas flow rate of 1 slm, and a methane gas flow rate of 0.01 slm. The substrate temperature at the end of the growth of the single crystal diamond was 1100 ° C. The formed single crystal diamond film had a thickness of 0.2 mm.

  After the growth, these diamond substrates were integrated, and the contact portions were uniformly covered with single crystal diamond.

[Comparative Example 1]
For two rectangular single crystal diamond (100) substrates having the same crystallographic properties, width 20 mm, length 40 mm, and thickness 0.5 mm, the off direction is evaluated using X-ray diffraction, and the length direction It was confirmed that the off direction had an angle of 90 degrees with respect to the ridgeline.

  Next, these single crystal diamond substrates are placed in a commercially available microwave plasma CVD apparatus so that the lengthwise sides are in contact with each other so that the off-directions of these single crystal diamond substrates are aligned. Using the apparatus, the microwave power is 10 kW, A single crystal diamond film was grown for 14 hours on the ion-implanted surface of the seed crystal at a gas pressure of 17 kPa, a hydrogen gas flow rate of 1 slm, and a methane gas flow rate of 0.01 slm. The substrate temperature at the end of the growth of the single crystal diamond was 1100 ° C. The formed single crystal diamond film had a thickness of 0.2 mm.

  After growth, these diamond substrates were not bonded.

Claims (5)

A method for producing a single crystal diamond substrate including the following steps:
(1) A plurality of single crystal diamond seed substrates having the same crystallographic properties, and the angles formed by the ridgelines of the seed substrate and the off direction of the seed substrate are all the same between the seed substrates. In addition, a plurality of single crystal diamond seed substrates on which the outer peripheral side surface of the main growth surface of the seed substrate is shaped and the length of the ridge line based on the shaped side surface exceeds 20 mm are shaped on the support base. A step of placing the seed substrates in such a manner that the side surfaces in the length direction of the seed substrates are in contact with each other, the off-directions of the seed substrates are matched, and the main growth surface of the seed substrate is exposed;
(2) A step of growing single crystal diamond on a main growth surface of a plurality of seed substrates placed on a support table in the step (1) and bonding the plurality of seed substrates. The outer circumference of the main growth surface of the seed substrate so that the angle formed by the ridgelines of the single crystal diamond seed substrate having the same crystallographic properties in the step (1) and the off direction of the seed substrate is less than 90 degrees. The manufacturing method of the single-crystal diamond substrate of Claim 1 by which the side surface was processed.   The outer periphery of the main growth surface of the seed substrate so that the angle formed by the ridgelines of the single crystal diamond seed substrate having the same crystallographic properties in the step (1) and the off direction of the seed substrate is 18 degrees or more. The manufacturing method of the single-crystal diamond substrate of Claim 1 or 2 by which the side surface was shaped.   The method for producing a single crystal diamond substrate according to any one of claims 1 to 3, wherein the same crystallographic property is an off direction and / or an off angle.   A single crystal diamond substrate obtained by the method according to claim 1.