WO2017038665A1 - Sapphire ribbon - Google Patents

Abstract

Provided is a sapphire ribbon that is grown by EFG. When pulling-up is complete, the r-axis direction of the sapphire ring can be determined by sight without using X-ray diffraction. According to the present invention, a sapphire ribbon that has an r-axis direction that can be seen by magnifying glass can be obtained by forming a multi-sapphire ribbon that has a c face as a main face thereof and by forming a two-layered euhedral face that comprises an r face and an R face on a spreading-part-side face of the sapphire ribbon.

Description

Sapphire ribbon

The present invention relates to a single crystal sapphire ribbon grown by the EFG method.

Currently, the method for growing a single crystal for a sapphire wafer used in a light emitting device such as an LED includes an EFG method for growing a sapphire ribbon by designating a crystal orientation plane, a Cz method for growing a cylindrical ingot, There are two main types. Among these, the growth method using the EFG method is characterized in that a plurality of plate crystals whose crystal orientations are specified by the crystal orientation of the seed substrate are collectively pulled up. 327495 (hereinafter described as Patent Document 1) has been published after the application. Further, the growth method using the Cz method is characterized in that a cylindrical ingot whose crystal orientation is designated by the crystal orientation of the seed substrate is easily increased in diameter and pulled up, and as a related technique, Japanese Patent Application Laid-Open No. 2010-189242. (Hereinafter described as Patent Document 2) has been published after filing.

Of these two cases, the technical feature of the invention described in Patent Document 1 is that the deviation angle between the crystal orientation of the seed substrate and the pulling axis is kept within a certain range, thereby enabling stable crystal growth. . In addition, the invention described in Patent Document 2 has a technical feature that the effective length of the ingot is increased by denting the bottom surface of the growing crucible and the yield of the wafer obtained from the ingot is improved.

JP2003-327495A JP 2010-189242

While having the above-described effects, in recent years, some sapphire c-plane wafers are required to have a wafer in which the r-axis direction is specified. The base material of the wafer is manufactured by cutting out from a single crystal obtained by the above growth method. For this reason, it is necessary to perform the determination in the r-axis direction using an X-ray diffractometer after cutting out in the Cz method described in Patent Document 2 and after growth in the EFG method described in Patent Document 1 in response to the request. Had.

In addition, since radiation management is required for the installation of the apparatus, the installation place is limited, and it is assumed that the apparatus is operated in an environment separated from a normal room. In addition, it is necessary to perform X-ray measurement for each grown and cut crystal, resulting in a problem that mass productivity is reduced.

In view of the above problems, the invention described in the present application aims to provide a sapphire ribbon capable of determining the r-axis direction without using X-ray diffraction.

For the above purpose, the invention described in the first aspect of the present invention is that a self-shaped surface divided in the thickness direction is formed on the side surface of the sprayed portion of the sapphire ribbon grown by the EFG method. It is a feature. More specifically, the side surface of the sprayed portion between the seed substrate and the wide portion formed when growing a wide sapphire ribbon having the c-plane as the main surface from the seed substrate is divided in the thickness direction, The technical feature is that two types of self-shaped surfaces that form a boundary with each other are provided.

In the invention described in the second aspect of the present invention, in the multi-sapphire ribbon having a plurality of sapphire ribbons grown from a common seed substrate by the EFG method, the seed substrate-wide portion of each sapphire ribbon Two types of self-shaped surfaces that are divided in the thickness direction and form a boundary between each other are provided on the side surface of the spraying portion formed between them, and the angle of the self-shaped surface is formed within a certain range. It is characterized by that. More specifically, the angle between the two types of self-shaped surfaces and the boundary is such that one is within the range of 41 ° ± 5 ° and the other is within the range of 51.5 ° ± 5 °. Its technical feature is the formation of a self-shaped surface.

Due to the technical features described above, the invention described in the first aspect of the present invention can provide a sapphire ribbon capable of determining the r-axis from the spraying part without using X-ray diffraction. It becomes. This is an effect obtained by forming the two types of self-shaped surfaces on the side surface of the spraying portion.

That is, the sapphire ribbon described in the present application is a single crystal sapphire ribbon grown by the EFG method, and a self-shaped surface is formed in the spraying portion by setting the pulling speed and the temperature condition in the growth furnace to specific conditions. ing. More specifically, among crystal planes of the sapphire single crystal, the (0001) plane (hereinafter referred to as c plane), the (1-102) plane (hereinafter referred to as r plane), the (-1104) plane (hereinafter referred to as R plane). The self-shaped surface consisting of the r-plane and the R-plane constituting the boundary is formed on the side surface of the spraying portion of the sapphire ribbon having the c-plane as the main surface. For this reason, in the sapphire ribbon described in the present application, the side of the r-shaped self-shaped surface that forms the self-shaped surface at a small angle with respect to the boundary is confirmed as compared with the R-surface, thereby orthogonal to the r-plane. It is possible to determine the direction of the r-axis.

As a condition for forming the self-shaped surface, in order to grow a crystal, an alumina melt, etc., an external supply of a crystal material to the seed substrate, a conformity between the crystal material and the seed substrate due to a crystal structure, It is necessary to satisfy the following three conditions: the degree of freedom of reaching the crystal surface by contact between the crystal material and the seed substrate, and the self-shaped surface is formed by the difference in growth rate in each crystal orientation. More specifically, a crystal orientation with a high growth rate continues to grow while leaving an adjacent crystal orientation with a low growth rate. For this reason, when the self-shaped surface is formed, the crystal orientation with a high growth rate is sharpened and disappears finally, and the self-shaped surface is formed with the adjacent crystal orientation with a low growth rate. Regarding the formation of the self-shaped surface, the growth rate of each crystal orientation in sapphire increases in the order of c-plane, r-plane, a-plane, and other planes, and the growth rate of c-plane becomes the slowest. ing. For this reason, in general sapphire ribbon growth for c-plane wafers, a c-shaped self-shaped surface is mainly formed on the sapphire ribbon surface.

In the invention described in the present application, in the growth using the EFG method, the self-shaped surface is formed on the side surface of the spraying portion by setting the pulling speed and the temperature condition, thereby enabling the determination of the r-axis direction. Further, in the EFG method used by the present application, the spraying portion is formed by making the width of the seed substrate end face in contact with the melt at the start of growth smaller than the width of the sapphire ribbon that is finally pulled up. For this reason, it is easy to improve the crystal quality by forming a single crystal sapphire as a seed substrate small, and it is possible to grow a plurality of the ribbons at the same time without causing crystal defects and the like on the c-plane. The growth of the sapphire ribbon can be stabilized, and the determination of the r-axis using the side surface of the spraying part can be made visually.

In addition to the effects described in the first aspect, by using the invention described in the second aspect of the present invention, all of the plurality of sapphire ribbons grown by c-plane multisapphire ribbon growth are used. It is possible to provide the same effect as that of the embodiment. That is, in the growth of the multi-sapphire ribbon, the growth conditions on each sapphire ribbon and the side surface of the spraying portion vary for each sapphire ribbon due to the temperature distribution in the furnace and the radiant heat between the adjacent sapphire ribbons. In the present invention, by keeping the shape of the self-shaped surface within a specific range, the growth of the sapphire ribbon is stabilized, and the effects described in the first aspect are given to each sapphire ribbon. Yes. More specifically, with reference to a boundary formed by two types of self-shaped surfaces formed on the side surface of the spraying section, the pulling speed and the temperature in the growth furnace are set so that the angle of each self-shaped surface is within a specific range. By adjusting the conditions, it is possible to visually determine the r-axis for all of the plurality of sapphire ribbons, and it is possible to grow single crystals of stable quality by suppressing crystal defects and the like for each sapphire ribbon. It becomes.

As described above, by using the invention described in the present application, it is possible to provide a sapphire ribbon capable of determining the r-axis direction without using X-ray diffraction.

The whole perspective view of the multi-sapphire ribbon used in the best embodiment of the present invention Explanatory drawing related to the crystal plane of the multi-sapphire ribbon shown in FIG. The self-shaped surface actually formed on the side surface s of the spraying part in FIG. Explanatory drawing which shows the growth process of the multi sapphire ribbon shown in FIG. Explanatory drawing which shows the growth process of the spraying part shown in FIG.

Hereinafter, the best embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, FIG. 3, FIG. 4 and FIG. In addition, about the symbol and component number in a figure, the common symbol or number is provided to what functions as the same component.

FIG. 1 is an overall perspective view of the multi-sapphire ribbon used in the present embodiment, FIG. 2 is an explanatory diagram relating to the crystal plane of the multi-sapphire ribbon, and FIG. 3 is formed on the side surface of the spraying portion of the multi-sapphire ribbon. FIG. 4 is an explanatory diagram related to the multi-sapphire ribbon growing process of FIG. 1, and FIG. 5 is an explanatory diagram related to the spraying part growing process of FIG. In addition, about the internal structure of a growth furnace, the clamp for raising, etc., description in a figure is abbreviate | omitted.

As shown in FIGS. 1, 2, and 3, in this embodiment, for each sapphire ribbon 3 of the multi-sapphire ribbon 1, two self-shaped surfaces each having an r-plane and an R-plane on each side s of the spraying portion Is formed. In the growth of the multi-sapphire ribbon used in this embodiment, the crystal orientation is specified by the crystal orientation (a1, a2, a3, c) shown in FIG. Among these, in this embodiment, the (0001) plane (hereinafter referred to as c-plane), the (1-102) plane (hereinafter described as r-plane), and the (-1104) plane (hereinafter described as R-plane) are used for spraying. A self-shaped surface composed of an r-plane and an R-plane constituting the boundary is formed on the side surface s of the ding portion. Accordingly, by confirming the self-shaped surface on the r-plane side shown in FIG. 3, the direction of the r-axis orthogonal to the r-plane can be determined, and after each sapphire ribbon 3 is separated from the seed substrate 2 In addition, the r-axis direction can be determined by visual observation using a magnifying glass by the side surface s of the spraying portion. As shown in FIG. 4, when the seed substrate 2 is pulled up from the alumina melt 5 to form the spraying portion, the pulling speed and the furnace temperature are adjusted, and the r-plane and R shown in FIGS. The angle formed by the boundary of each self-shaped surface with the surface and each self-shaped surface is grown so that the r-plane is within the range of 51.5 ° ± 5 ° and the R-plane is within the range of 41 ° ± 5 °. . That is, as can be seen from FIG. 1, in the EFG method described in the present embodiment, the thicknesses of the sapphire ribbons 3 are adjusted to a constant value and are grown in a state of being arranged at equal intervals. For this reason, the difference in the growth conditions between the sapphire ribbons can be minimized, and the angle of the self-shaped surface formed on the spraying side surface s can be kept within a certain range. Here, in this embodiment, the pulling rate is fixed at 25 mm / hour ± 25%, and the furnace temperature is gradually increased from 2050 ° C. at which the temperature of the die pack 4 becomes the melting point just before solidification, and spraying over the entire width at 2055 ° C. It is set to form a surface. Further, as shown in FIG. 3, the width of the self-shaped surface with respect to the formed boundary is formed to be larger on the r-plane side than on the R-plane side in this embodiment (1: 2 to 2: 3). ). For this reason, in each sapphire ribbon 3 in the present embodiment, it is possible to determine the crystal orientation not only by the angle but also by the width of the self-shaped surface.

4 and 5 show the growing process of the spraying part used in the present embodiment. Regarding the crystal growth conditions described above, in the present embodiment, the alumina melt 5 made of the same raw material is used for the seed substrate 2 made of single crystal sapphire with the c-axis at the end for growing a c-plane sapphire ribbon. Meets crystal material supply and adaptability. The degree of freedom to reach the crystal surface is satisfied when the seed substrate 2 comes into contact with the melt 5. That is, in this embodiment, by providing the die pack 4 having a plate-like gap through the gap g in the crucible, the surface of the alumina melt 5 melted in the crucible reaches the tip of the die pack by capillary action. I am letting. Therefore, the temperature difference generated between the sapphire ribbons during the growth of the multi-sapphire ribbon 1 can be reduced, and the growth conditions when the seed substrate 2 is pulled up can be stabilized. 4 and 5, when the seed substrate contacts the melt that has reached the end of the die pack, the die pack 4 described in the present application moves in the width direction of the seed substrate 2. Crystal growth in the spraying portion proceeds, and when the width dimension of the die pack 4 is reached, the process proceeds to flat plate-shaped sapphire ribbon growth as shown in FIG. This is because the melt is supplied from the width direction of the die pack to the side surface of the bottom portion of the seed substrate by the surface tension of the melt 5, and the crystal size in the thickness direction is previously limited by the die pack during the crystal growth. By being.

That is, with regard to the growth of the spraying part spreading in the width direction, in the crystal growth using the EFG method, when the supply of new melt from the width direction is stopped by the die, the crystal can grow in that direction. First, the thickness is kept constant by the die, and the width dimension is also kept at a constant value. On the other hand, if the melt is supplied, the size of the crystal increases in that direction, and the shape balance is lost. Along with this, the EFG method used in the present embodiment forms a self-shaped surface in the spraying portion by freely supplying the melt from the liquid surface when the spraying portion is expanded in the width direction. It is possible to do. Here, referring to FIGS. 5A to 5C where the width of the sapphire ribbon is widened, it can be seen that the melt is freely supplied in the width direction. The EFG method used in the present embodiment has a structure in which crystal growth starts from the front and back surfaces of the die due to the die shape. For this reason, in this embodiment, by optimizing the pulling speed and temperature conditions to form a self-shaped surface on the side surface of the spraying part, the crystal structure differs between the front surface and the back surface. A self-shaped surface divided into two could be formed on the side surface.

As described above, by using the structure described in the present embodiment, a sapphire ribbon capable of visually determining the r-axis direction without using X-ray diffraction can be provided.

1 Multi-Sapphire Ribbon 2 Seed Substrate 3 Sapphire Ribbon 4 Die Pack 5 Alumina Melt c c-plane Crystal Orientation g Gap r r-plane Crystal Orientation R R-plane Crystal Orientation s Spraying Side

Claims (2)

1. The spraying part side surface is divided in the thickness direction by a region formed by a collection of self-shaped surfaces,
   Of the angles formed by the boundary between the divided areas and the self-shaped surface itself, one of the self-shaped surfaces is formed within a range of 41 ° ± 5 ° and the other of 51.5 ° ± 5 °. Sapphire ribbon.
2. Each sapphire ribbon spraying part side surface is divided in the thickness direction by a region formed by a collection of self-shaped surfaces
   Of the angles formed by the boundary between the divided areas and the self-shaped surface itself, one of the self-shaped surfaces is formed within a range of 41 ° ± 5 ° and the other of 51.5 ° ± 5 °. Multi-sapphire ribbon.

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