WO2016043176A1

WO2016043176A1 - Plurality of sapphire single crystals and method of manufacturing same

Info

Publication number: WO2016043176A1
Application number: PCT/JP2015/076102
Authority: WO
Inventors: 古滝　敏郎; 弘倫斎藤; 数人樋口; 高橋　正幸; 佐藤　次男
Original assignee: 並木精密宝石株式会社
Priority date: 2014-09-19
Filing date: 2015-09-15
Publication date: 2016-03-24
Also published as: JP2016060672A; JP5895280B1; TW201625823A

Abstract

Provided are a plurality of sapphire single crystals and a method of manufacturing the same that can prevent crystal defects by preventing flatting and improving heat balance by optimally setting the gap between dies or the gap between sapphire single crystals with respect to the thickness of the dies or the maximum thickness of the plurality of sapphire single crystals. A plurality of sapphire single crystals are manufactured by: housing a plurality of dies, each having a slit, in a crucible; charging an aluminum oxide raw material into the crucible and heating the aluminum oxide raw material to form a molten pile of aluminum oxide above the slits; causing seed crystals to touch the molten pile and then withdrawing the seed crystals from the molten pile to grow a plurality of sapphire single crystals; and setting a gap D between the dies to 0.33 to 0.67 times the thickness t of the dies. A gap d between the plurality of sapphire single crystals is set to 0.33 to 0.67 times the maximum thickness tm of the sapphire single crystals, among the thicknesses of the plurality of sapphire single crystals.

Description

Multiple sapphire single crystals and method for producing the same

The present invention relates to a plurality of sapphire single crystals and a manufacturing method thereof.

Currently, a sapphire single crystal substrate is widely used as a semiconductor substrate material typified by a light emitting element such as an LED (Light Emitting Diode). Mass production methods for sapphire single crystal substrates are roughly classified into CZ method (Czochralski method) and EFG method (Edge-defined Film-fed. Growth method).

The CZ method is a method in which a sapphire single crystal serving as a substrate material is grown in a lump in an ingot and sliced from the ingot obtained by the growth into a substrate. On the other hand, the EFG method is a method of growing a sapphire single crystal into a flat plate shape and cutting out the sapphire single crystal obtained by the growth into an arbitrary shape. Among these two growth methods, a method for simultaneously growing a plurality of sapphire single crystals using the EFG method has been filed and published (for example, see Patent Document 1).

In the single crystal manufacturing method described in Patent Document 1, the seed crystal is arranged in a direction perpendicular to the longitudinal direction of the liquid surface of the raw material melt for growing the flat sapphire single crystal, and the seed crystal is pulled up. A plurality of flat sapphire single crystals are produced. Since a plurality of sapphire single crystals can be grown at once, the mass productivity of the sapphire single crystals can be improved.

Japanese Patent No. 4465481

However, in the manufacturing method described in Patent Document 1, single crystals stick to each other between a plurality of sapphire single crystals, and there is a possibility that flatting may occur. As a cause of the flatting, it is conceivable that the gap between the dies forming the liquid pool of the raw material melt is set too small. If the gap between the dies is set too small, the seed crystal will enter the gap between the dies when the seed crystal is brought into contact with the surface of the raw material melt and the die to melt part of the seed crystal. There has been a problem that flattening occurs and adjacent sapphire single crystals stick together to be integrated. When flatting occurred, the integrated sapphire single crystal became a defective product, leading to a decrease in mass productivity and yield. Further, when the gap between the dies is reduced, the gap between the plurality of sapphire single crystals is also reduced, which causes the occurrence of flatting.

Furthermore, if the gap between the dies is set too small, the gap between the sapphire single crystals also becomes small, the thermal balance between the sapphire single crystals deteriorates, and other individual sapphire single crystals that are free from the occurrence of flatting This will cause crystal defects. Therefore, not only the flatting but also the crystal quality of the sapphire single crystal is lowered, which causes a significant reduction in mass productivity.

The present invention has been made in light of the above circumstances, and optimally sets the gap between dies or the gap between sapphire single crystals with respect to the thickness of the die or the maximum thickness of a plurality of sapphire single crystals. Therefore, it is an object to provide a plurality of sapphire single crystals and a manufacturing method thereof that can prevent crystal defects by preventing flattening and improving thermal balance.

The above-mentioned subject is achieved by the following present invention. That is,
(1) In the method for producing a plurality of sapphire single crystals of the present invention, a plurality of dies having slits and arranged in parallel in the longitudinal direction are accommodated in a crucible, and an aluminum oxide raw material is charged into the crucible and heated. Then, an aluminum oxide raw material is melted in a crucible to prepare an aluminum oxide melt, an aluminum oxide melt pool is formed at the upper part of the slit through a slit, and a seed crystal is brought into contact with the aluminum oxide melt at the upper part of the slit. By pulling up the seed crystal, a plurality of sapphire single crystals having a desired main surface are grown, and the gap D between the dies is set to be 0.33 times or more and 0.67 times or less of the die thickness t, and the plurality of sapphire single crystals are set. It is characterized by producing crystals.

(2) In one embodiment of the method for producing a plurality of sapphire single crystals of the present invention, the gap D is further within a range of 0.33 to 0.67 times the thickness t.

Is preferably satisfied.

(3) Further, the plurality of sapphire single crystals of the present invention are formed from a common seed crystal, and the gap d between the sapphire single crystals is 0.33 which is the maximum thickness tm among the thicknesses of the plurality of sapphire single crystals. It is set to be not less than twice and not more than 0.67 times.

(4) In one embodiment of the plurality of sapphire single crystals of the present invention, the gap d is within the range of 0.33 times to 0.67 times the thickness tm.

Is preferably satisfied.

(5) In another embodiment of the plurality of sapphire single crystals of the present invention, the angle of deviation of the crystal axes of the main surfaces of the plurality of sapphire single crystals is preferably in the range of 0.5 ° or less.

According to the inventions of (1) and (3), the gaps D and d set in the range of 0.33 to 0.67 times the die thickness t or the maximum thickness tm of the plurality of sapphire single crystals. Thus, a plurality of sapphire single crystals are formed. By forming a plurality of sapphire single crystals with such a gap D or d, it is possible to prevent the seed crystal from entering the gap between the dies or the gap between the sapphire single crystals, and to prevent the occurrence of fluttering. It becomes possible to eliminate sticking between sapphire single crystals.

Furthermore, by setting the gap D or d as described above, it is possible to prevent the melts of adjacent dies from being connected by the surface tension at the time of contact between the seed crystal and the melt pool. Therefore, it became possible to grow a sapphire single crystal with higher mass productivity by eliminating the decrease in yield. Furthermore, it is possible to prevent the occurrence of crystal defects due to flatting.

Furthermore, since the gap D between the dies as a guide can be known, it is possible to reduce the number of verifications of optimization of the gap D between the dies, and as a result, the development of the growth of a plurality of sapphire single crystals and the improvement of the crystal quality. It becomes possible to improve the speed.

Further, according to the inventions of the above (2) and (4), in addition to preventing the occurrence of flattening and the occurrence of crystal defects due to the flatting, the thermal balance between each sapphire single crystal grown and grown is crystallized. It became possible to hold in an optimal state suitable for breeding. In addition, the growth condition of each sapphire single crystal can be maintained uniformly by maintaining the heat balance. For this reason, it is possible to pull up a plurality of sapphire single crystals having no crystal parts such as line defects and crystal grain boundaries and having improved crystal quality. Therefore, a plurality of more practical sapphire single crystals can be pulled up simultaneously, and it becomes possible to further improve yield and mass productivity.

Further, according to the invention of (5), it is possible to keep the polishing amount necessary for correcting the deviation angle of the crystal axis for each sapphire single crystal to about 1.5 mm in the thickness direction of the sapphire single crystal. . For this reason, it becomes possible to improve the workability of the sapphire single crystal as the semiconductor substrate.

It is a schematic block diagram which shows the manufacturing apparatus of the sapphire single crystal by EFG method. (a) It is a top view which shows typically an example of the die | dye which concerns on embodiment of this invention. (b) It is a front view of the figure (a). (c) It is a side view of the same figure (a). (a) It is explanatory drawing which shows an example of the seed crystal which concerns on embodiment of this invention. (b) It is explanatory drawing which shows the other example of the seed crystal which concerns on embodiment of this invention. (c) It is explanatory drawing which shows the further another example of the seed crystal which concerns on embodiment of this invention. It is a perspective view which shows typically the positional relationship of the seed crystal and partition plate in embodiment of this invention. (a) It is a front view which shows typically the positional relationship of the seed crystal and partition plate in embodiment of this invention. (b) It is a front view which shows a mode that a part of seed crystal is fuse | melted in embodiment of this invention. It is a perspective view which shows typically a mode that the neck in embodiment of this invention grows. (a) In the seed crystal which concerns on embodiment of this invention, a lower side is explanatory drawing which shows a comb-tooth shaped seed crystal. (b) In the seed crystal which concerns on embodiment of this invention, a lower side is explanatory drawing which shows a saw-shaped seed crystal. It is a perspective view which shows typically the spreading process of the sapphire single crystal which concerns on embodiment of this invention. It is a perspective view which shows partially the several sapphire single crystal which concerns on embodiment of this invention obtained by EFG method. It is a perspective view which shows typically the positional relationship of a seed crystal and a partition plate in the example of a change of embodiment of this invention. (a) It is a front view of the seed crystal which concerns on the example of a change of embodiment of this invention. (b) It is a top view of the figure (a). (c) It is a side view of the same figure (a). (a) It is a bottom view of the sapphire single crystal grown using the seed crystal of FIG. (B) is a front view of FIG. (c) It is a side view of the same figure (a). (a) It is a front view of the seed crystal concerning the other modification of this invention. (b) It is a top view of the figure (a). (c) It is a side view of the same figure (a). It is explanatory drawing which shows the positional relationship of the seed crystal shown in FIG. 13, and a partition plate.

Hereinafter, a plurality of sapphire single crystals and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to FIGS. 1 to 10.

As shown in FIG. 1, the sapphire single crystal manufacturing apparatus 1 includes a growth container 3 for growing a sapphire single crystal 2 and a pulling container 4 for pulling up the grown sapphire single crystal 2. -fed. Growth) method is used to grow and grow sapphire single crystal 2.

The growth container 3 includes a crucible 5, a crucible drive unit 6, a heater 7, an electrode 8, a die 9, and a heat insulating material 10. The crucible 5 is made of molybdenum and melts the aluminum oxide raw material. The crucible drive unit 6 rotates the crucible 5 with the vertical direction as an axis. The heater 7 heats the crucible 5. The electrode 8 energizes the heater 7. The die 9 is installed in the crucible 5 and determines the liquid surface shape of an aluminum oxide melt (hereinafter simply referred to as “melt” if necessary) 21 when pulling up the sapphire single crystal 2. The heat insulating material 10 surrounds the crucible 5, the heater 7 and the die 9.

Furthermore, the growth vessel 3 includes an atmospheric gas inlet 11 and an exhaust port 12. The atmosphere gas introduction port 11 is an introduction port for introducing, for example, argon gas into the growth vessel 3 as the atmosphere gas, and prevents oxidation of the crucible 5, the heater 7, and the die 9. On the other hand, the exhaust port 12 is provided for exhausting the inside of the growth vessel 3.

The pulling container 4 includes a shaft 13, a shaft driving unit 14, a gate valve 15, and a substrate inlet / outlet 16, and pulls up a plurality of flat plate-shaped sapphire single crystals 2 grown from the seed crystal 17. The shaft 13 holds a seed crystal 17. Further, the shaft driving unit 14 moves the shaft 13 up and down toward the crucible 5 and rotates the shaft 13 around the lifting direction. The gate valve 15 partitions the growth container 3 and the lifting container 4. The substrate entrance / exit 16 takes in and out the seed crystal 17.

The manufacturing apparatus 1 also has a control unit (not shown), and the rotation of the crucible drive unit 6 and the shaft drive unit 14 is controlled by this control unit.

Next, the die 9 will be described. The die 9 is made of molybdenum and has a number of partition plates 18 as shown in FIG. As an example of the die, FIG. 2 shows a case where there are 30

partition plates

18 and 15 dies 9 are formed. The partition plates 18 have the same flat plate shape and are arranged in parallel to each other so as to form a minute gap (slit) 19 to form one die 9. The slit 19 is provided over almost the entire width of the die 9. Further, since the plurality of dies 9 have the same shape and are arranged in parallel at a predetermined interval so that the longitudinal directions thereof are parallel to each other, a plurality of slits 19 are provided. A slope 30 is formed on the upper part of each partition plate 18, and an acute angle opening 20 is formed by arranging the slopes 30 to face each other. The slit 19 has a role of raising the melt 21 from the lower end of each die 9 to the opening 20 by capillary action.

The aluminum oxide raw material charged into the crucible 5 is melted (raw material melt) based on the temperature rise of the crucible 5 to become a melt 21. A part of the melt 21 enters the slit 19 of the die 9, and ascends in the slit 19 based on the capillary phenomenon as described above and is exposed from the opening 20. 22 is formed (see FIG. 5A). In the EFG method, the sapphire single crystal 2 grows according to the shape of the melt surface formed by the aluminum oxide melt pool (hereinafter referred to as “melt pool” if necessary) 22. In the die 9 shown in FIG. 2, the shape of the melt surface is an elongated rectangle, so that a flat sapphire single crystal 2 is manufactured.

Next, the seed crystal 17 will be described. As shown in FIGS. 1, 4, and 5, in this embodiment, a flat substrate is used as the seed crystal 17, and the c-axis is along the surface direction of the main surface (a surface orthogonal to the crystal surface 28). A horizontal sapphire single crystal substrate is used. Further, the seed crystal 17 is arranged so that the planar direction of the seed crystal 17 and the longitudinal direction of the die 9 are orthogonal to each other at an angle of 90 °. Accordingly, the c-axis of the seed crystal 17 is perpendicular to the partition plate 18. Further, since the seed crystal 17 and the sapphire single crystal 2 are also orthogonal to each other at an angle of 90 °, FIG. 1 shows the side surface of the sapphire single crystal 2. By making the positional relationship between the plane direction of the seed crystal 17 and the longitudinal direction of the partition plate 18 perpendicular (by crossing the seed crystal 17 with the partition plate 18), the contact area between the melt 21 and the seed crystal 17 is minimized. It becomes possible to do. Therefore, the contact part of the seed crystal 17 becomes easy to become familiar with the melt 21, and the generation of crystal defects in the sapphire single crystal 2 is reduced or eliminated.

If the contact area with the substrate holder (not shown) under the shaft 13 is large, the seed crystal 17 is deformed due to a stress due to a difference in thermal expansion coefficient, and may be damaged in some cases. Conversely, the fixation of the seed crystal 17 may be loosened due to the difference in thermal expansion coefficient. Therefore, it is preferable that the contact area between the seed crystal 17 and the substrate holder is small. The seed crystal 17 needs to have a substrate shape that can be securely fixed to the substrate holder.

FIG. 3 is a diagram showing an example of the substrate shape of the seed crystal 17. Among these, FIGS. 4A and 4B show a case where a notch 23 is provided in the upper part of the seed crystal 17. Using this notch 23, for example, a U-shaped substrate holder can be inserted from the lower side of the two notches 23 to securely hold the seed crystal 17 while reducing the contact area. Become.

Further, as shown in FIG. 3C, a notch hole 24 may be provided inside the seed crystal 17. Using this cutout hole 24, for example, locking claws are inserted into the two cutout holes 24 to securely hold the seed crystal 17 while reducing the contact area between the substrate holder and the seed crystal 17. It becomes possible.

Next, a method for manufacturing the sapphire single crystal 2 using the manufacturing apparatus 1 will be described. First, a predetermined amount of granulated aluminum oxide raw material powder (99.99% aluminum oxide), which is a sapphire raw material, is charged into a crucible 5 in which a die 9 is stored. The aluminum oxide raw material powder may contain compounds and elements other than aluminum oxide depending on the purity or composition of the sapphire single crystal to be produced.

Subsequently, in order not to oxidize the crucible 5, the heater 7, or the die 9, the inside of the growth vessel 3 is replaced with argon gas, and the oxygen concentration is set to a predetermined value or less.

Next, the crucible 5 is heated to a predetermined temperature by the heater 7 to melt the aluminum oxide raw material powder. Since the melting point of aluminum oxide is about 2050 ° C. to 2072 ° C., the heating temperature of the crucible 5 is set to a temperature higher than the melting point (for example, 2100 ° C.). After a while after heating, the raw material powder is melted and an aluminum oxide melt 21 is prepared. Further, a part of the melt 21 rises through the slit 19 of the die 9 by capillary action to reach the surface of the die 9, and a melt pool 22 is formed on the slit 19.

Next, as shown in FIGS. 4 and 5, the seed crystal 17 is lowered while being held at an angle perpendicular to the longitudinal direction of the melt reservoir 22 above the slit 19, so that the seed crystal 17 is melted in the melt reservoir 22. Touch the liquid surface. The seed crystal 17 is previously introduced into the pulling container 4 from the substrate entrance 16. In FIG. 4, the melt 21 and the melt reservoir 22 are not shown in order to prioritize the visibility of the slit 19 and the opening 20.

FIG. 4 is a diagram showing the positional relationship between the seed crystal 17 and the partition plate 18. As described above, the contact area between the seed crystal 17 and the melt 21 can be reduced by making the plane direction of the seed crystal 17 orthogonal to the longitudinal direction of the partition plate 18. Therefore, the contact portion of the seed crystal 17 becomes compatible with the melt 21, and crystal defects are less likely to occur in the grown and grown sapphire single crystal 2. Furthermore, by reducing the contact area between the melt 21 and the seed crystal 17, the neck 25 described later can be formed thinly. Also in this respect, the generation of crystal defects in the sapphire single crystal 2 is reduced or eliminated, It becomes possible to keep the crystal quality high. Therefore, the yield of the sapphire single crystal 2 can be improved.

When the seed crystal 17 is brought into contact with the melt surface, the lower part of the seed crystal 17 may be brought into contact with the upper part of the partition plate 18 and melted. FIG. 5 (b) is a diagram showing how a part of the seed crystal 17 is melted. By melting part of the seed crystal 17 in this way, the temperature difference between the seed crystal 17 and the melt 21 can be quickly eliminated, and the generation of crystal defects in the sapphire single crystal 2 can be further reduced. It becomes possible.

Subsequently, the substrate holder is pulled up at a predetermined rising speed to start pulling up the seed crystal 17, and a neck 25 is formed as shown in FIG. Specifically, first, a thin neck 25 is produced (necked) while the substrate holder is raised at high speed by the shaft 13. Hereinafter, this process is referred to as a necking process. FIG. 6 is an explanatory view showing how the neck 25 grows. The neck 25 is a crystal portion having a thin diameter about the thickness T of the seed crystal 17 or the width of the melt pool 22, and is formed to reduce or eliminate crystal defects. Further, the length of the neck 25 is formed up to about three times its diameter. When the crystal is grown to this extent, even if a crystal defect occurs at the neck 25, the defect is prevented from being formed up to the sapphire single crystal 2. Therefore, by passing through the necking step, it is possible to produce a flat sapphire single crystal 2 with reduced or eliminated crystal defects.

In addition, according to the manufacturing method of this embodiment, compared with the manufacturing method which makes a seed crystal and a melt surface contact in parallel, it is a raw material required for pulling up the sapphire single crystal 2 until a crystal defect is removed. Therefore, the manufacturing cost can be reduced. In addition, since the time until crystal defects are completely removed in the pulling direction of the sapphire single crystal 2 can be shortened, the manufacturing speed can be improved.

In order to make the necking process easier, irregularities may be provided on the lower side of the seed crystal 17. FIG. 7 is a diagram illustrating the shape of the lower side of the seed crystal 17. FIG. 7A shows a case where the lower side has a comb shape, and FIG. 7B shows a case of a saw shape.

The interval between the irregularities is matched with the interval between the openings 20 and the convex portion is aligned with the center of the melt reservoir 22. By providing the convex portion, the convex portion can be used as the growth starting point of the sapphire single crystal 2, and the neck 25 can be formed more easily. Note that the shape of the unevenness is not limited to that shown in FIG. 7, and may be, for example, a corrugated uneven shape.

After passing through the necking step, the heater 7 is controlled to lower the temperature of the crucible 5 and the substrate holder is set at a predetermined speed, and the sapphire single crystal as shown in FIG. 2 is grown so as to be widened in the longitudinal direction of the die 9 (spreading). When the sapphire single crystal 2 is widened to the full width of the die 9 (the end of the partition plate 18) (full spread), a flat sapphire single crystal 2 having a large area and having the same width as the full width of the die 9 is grown. (Straight cylinder process). FIG. 8 is a schematic diagram showing how the width of the sapphire single crystal 2 is expanded by the spreading process. By obtaining a wide sapphire single crystal 2, the yield of sapphire single crystal products is improved.

After the sapphire single crystal 2 is grown to the full width of the die 9 by the spreading process, as shown in FIG. 9, a flat plate portion 26 having a constant width similar to the full width of the die 9 is formed at a predetermined speed. The flat sapphire single crystal 2 is obtained by pulling up to a predetermined length (straight body length).

After this, the obtained sapphire single crystal 2 is allowed to cool, the gate valve 15 is opened, the sapphire single crystal 2 is moved to the pulling container 4 side, and taken out from the substrate entrance 16. The appearance of the obtained flat plate-shaped sapphire single crystal 2 is shown in FIG. Although the length of the straight body is not particularly limited, it is preferably 2 inches or more (50.8 mm or more).

By using the manufacturing apparatus 1, seed crystal 17, and die 9 as described above, a plurality of sapphire single crystals 2 can be simultaneously manufactured from the common seed crystal 17. Therefore, the manufacturing cost of the sapphire single crystal 2 per sheet can be reduced.

In the EFG method, the plurality of sapphire single crystals 2 are grown and grown while the plane direction of the main surface 27 of the plurality of sapphire single crystals 2 is the same as the crystal plane 28 of the seed crystal 17. As an example, when the seed crystal 17 is made of a sapphire single crystal and the crystal plane 28 is a c-plane, all the main surfaces 27 of the obtained flat plate-shaped sapphire single crystal 2 can be the c-plane. Therefore, it is possible to obtain a plurality of sapphire single crystals 2 with no variation in view of the crystal direction.

Therefore, the die 9 including the seed crystal 17 and the partition plate 18 needs to be precisely positioned. Therefore, as shown in FIG. 1, the manufacturing apparatus 1 is provided with a crucible driving unit 6 that rotates the crucible 5 in which the die 9 is installed, and a control unit (not shown) that controls the rotation. The shaft 13 is also provided with a shaft drive unit 14 that rotates the shaft 13 and a control unit (not shown) that controls the rotation thereof. That is, the positioning of the seed crystal 17 with respect to the die 9 is adjusted by rotating the shaft 13 or the crucible 5 by the control unit.

Note that the precise positioning of the seed crystal 17 and the die 9 can also be performed by using the die 9 in which a part of the slope 30 of each partition plate 18 is cut out. FIG. 10 is a view showing an example in which a notch 29 is provided in the die 9. In FIG. 10, as an example, dies 9 each having a V-shaped notch 29 are shown in the center in the longitudinal direction of the inclined surface 30.

The notch 29 is formed on a straight line in the thickness direction of the die 9. By providing such a notch 29, positioning at the time of contact between the seed crystal 17 and the melt surface is facilitated, and variations in product quality between the sapphire single crystals 2 can be reduced or eliminated. .

The crystal plane 28 of the seed crystal 17 is not limited to the c plane, and can be set to a desired crystal plane such as an r plane, a plane, m plane, and the like. Thus, by arbitrarily setting the crystal plane 28, the plane direction of the main surface 27 of the sapphire single crystal 2 can be arbitrarily changed.

In addition to the effects described above, in the present embodiment, a plurality of sapphire single crystals 2 are manufactured by setting the gap D between the dies 9 within a range of 0.33 times to 0.67 times the thickness t of the dies 9. . Specifically, if the die 9 is manufactured with a thickness t in the range of 2.0 mm to 6.5 mm, the gap D between the dies 9 is a minimum of 0.68 mm (0.33 × 2.0 mm) to a maximum of 4.36 mm (0.67). X6.5 mm). However, the calculated value of the gap D was rounded off to the third decimal place.

By setting the gap D in this way, the gap d between the sapphire single crystals 2 formed from the common seed crystal 17 is 0.33 times or more of the maximum thickness tm among the thicknesses of the sapphire single crystals 2. It is set to 0.67 times or less (see FIG. 9). Even if the thickness of the plurality of sapphire single crystals 2 varies, the maximum thickness of the plurality of sapphire single crystals 2 does not exceed the thickness t of the die 9. Therefore, ideally, the thickness t and the thickness tm are equal, and the gap D and the gap d are formed equally. By forming a plurality of sapphire single crystals 2 with such gaps D or d, the seed crystal 17 is prevented from entering the gaps between the dies 9 or the gaps between the sapphire single crystals 2, and the occurrence of flatting. As a result of verification, the present applicant has found that it is possible to prevent the sticking between adjacent sapphire single crystals 2. Furthermore, since the gap D or d is set as described above, it is possible to prevent the melts 21 of the adjacent dies 9 from being connected by surface tension at the time of contact between the seed crystal 17 and the melt pool 22. Thus, it was possible to grow the sapphire single crystal 2 with higher mass productivity. Furthermore, it is possible to prevent the occurrence of crystal defects due to flatting.

Further, since the gap D between the dies as a guide is known, it is possible to reduce the number of times of verification of optimization of the gap D between the dies. It becomes possible to improve the improvement speed.

Further, regarding the growth of the sapphire single crystal 2 having the width and thickness, a preferable setting value of the thickness T of the seed crystal 17 is 2 mm or more. By setting the thickness T to 2 mm or more, deformation of the seed crystal 17 during pulling of the sapphire single crystal 2 is prevented, and the main surface 27 of the sapphire single crystal 2 to be grown and the crystal surface 28 of the seed crystal 17 are grown. It was possible to suppress the deviation angle in the crystal axis direction. Furthermore, the strength of the seed crystal 17 is maintained even under high temperature conditions of the crucible 5, and the deformation of the seed crystal 17 due to the own weight of the seed crystal 17 itself can be prevented in addition to the weight of each sapphire single crystal 2 grown and grown. The effect of suppressing the deviation angle in the crystal axis direction can be obtained.

In addition to the above-described effects, in this embodiment, the angle of deviation of the crystal axis of the main surface 27 between the sapphire single crystals 2 can be kept within a range of 0.5 ° or less due to the shape of the seed crystal 17 and its rigidity. . More specifically, the deformation of the seed crystal 17 is prevented with respect to the weight of the sapphire single crystal 2 that increases as the crystal growth increases, and the crystal plane 28 of the seed crystal 17 and the sapphire single crystal 2 The shape of the seed crystal 17 is set such that the deviation angle in the crystal axis direction generated between the main surface 27 and the crystal surface is within 0.5 ° or less. As a result, the polishing amount necessary for correcting the deviation angle of the crystal axis for each sapphire single crystal 2 can be reduced to about 1.5 mm in the thickness direction of the sapphire single crystal 2. For this reason, the sapphire single crystal 2 of the present embodiment also has an effect of improving workability as a semiconductor substrate.

According to the manufacturing method of the present embodiment, it is possible to form a plurality of large sapphire single crystals 2 maintaining crystal quality from a common seed crystal 17 at a time.

More preferably, the gap D is within a range of 0.33 to 0.67 times the thickness t.

Is set to satisfy.

By setting the gap D in this way, the gap d between the sapphire single crystals 2 formed from the common seed crystal 17 is also within a range of 0.33 to 0.67 times the thickness tm.

Will satisfy the relationship. Specifically, assuming that the thickness t of the die 9 is manufactured in the range of 2.0 mm to 6.5 mm, the gap D between the dies 9 is in the range of 0.96 mm to 2.28 mm from the minimum according to Equation 3. Will be set. However, the calculated value of the gap D was rounded off to the third decimal place.

As described above, the gap D and the gap d are ideally formed equally. By forming a plurality of sapphire single crystals 2 with such gaps D or d, in addition to preventing the occurrence of the flatting and the generation of crystal defects due to the flatting, further, between the sapphire single crystals 2 It is possible to maintain a uniform heat balance in the crucible 5 by the temperature in the crucible 5 and the radiant heat between the sapphire single crystals 2. Therefore, a plurality of sapphire single crystals 2 with improved crystal quality can be grown and grown simultaneously.

More specifically, the temperature at the end face of each sapphire single crystal 2 is kept uniform by the melt pool 22 on the die 9 and the radiant heat between the sapphire single crystals 2, and between the sapphire single crystals 2 grown and grown. It became possible to maintain the heat balance in an optimum state suitable for crystal growth. In addition, in this embodiment, it is possible to keep the growth conditions of each sapphire single crystal 2 uniform by maintaining the heat balance. For this reason, it becomes possible to pull up a plurality of sapphire single crystals 2 having no crystal parts such as line defects and crystal grain boundaries and having improved crystal quality. Therefore, a plurality of more practical sapphire single crystals 2 can be pulled up simultaneously, and it becomes possible to further improve yield and mass productivity.

Note that if the gap D or the gap d is less than 0.33 times the thickness t or the thickness tm, flatting occurs. On the other hand, when it exceeds 0.67 times, the gap D or the gap d is excessively opened, the number of sapphire single crystals that can be manufactured at one time is reduced, and the mass productivity is lowered. Therefore, in the present invention, the gap D or the gap d is set to be 0.33 times or more and 0.67 times or less of the thickness t or the thickness tm as a range in which it is possible to achieve both prevention of flatting while ensuring mass productivity.

It should be noted that the thickness variation of the sapphire single crystal 2 and the thickness variation over the length of the straight body of each sapphire single crystal 2 is t (see FIG. 2 (b), FIG. 4, etc.). ), Being within the range of 0.01 t or more and 0.1 t or less is preferable from the viewpoint that it is possible to prevent the adjacent sapphire single crystals 2 from sticking (flatting).

It should be noted that the present invention is not limited to the above-described embodiment, and can be implemented with configurations within a range that does not deviate from the contents described in the respective claims. That is, the invention has been illustrated and described with particular reference to particular embodiments, but with respect to the embodiments described above without departing from the spirit and scope of the invention, Those skilled in the art can add various modifications to the detailed configuration.

For example, the present invention can be applied to the growth of a sapphire single crystal having a step structure on the main surface. In the method for manufacturing a sapphire single crystal by the EFG method in which the main surface of the sapphire single crystal is, for example, c-plane, the m-axis of the seed crystal is aligned with the pulling direction of the sapphire single crystal. Furthermore, the c-axis of the seed crystal positioned in the direction perpendicular to the pulling direction is a predetermined angle (for example, 0.05 ° or more) in the a-axis direction with respect to the normal of the main surface of the sapphire single crystal with the pulling direction as the rotation axis It is also possible to grow by inclining. In addition, the description which overlaps with the said embodiment is abbreviate | omitted or simplified.

Here, the seed crystal in which the c-axis is inclined will be described with reference to FIG. An orthogonal coordinate system in which the normal of the plane of the seed crystal 31 shown in FIG. 11 is the Z axis, the normal of the side surface (crystal plane) of the seed crystal 31 is the Y axis, and the normal of the front of the seed crystal 31 is the X axis. It explains using. The Z axis is arranged in parallel to the pulling direction of the sapphire single crystal.

The c-axis of the seed crystal 31 is adjusted so that the angle α formed with the Z-axis (the axis in the pulling direction) is within a predetermined range (for example, 90 ° ± 0.5 °), as shown in FIG. Further, as shown in FIG. 11B, the c-axis is inclined at a predetermined angle β (for example, a range of 0.05 ° or more and 1.0 ° or less) in the X-axis direction (a-axis direction). On the other hand, the m-axis in the pulling-up axis direction (Z-axis direction) is perpendicular to the c-axis as shown in FIG. 11 (a), and the m-axis is as shown in FIG. 11 (c). The deviation angle γ from the pulling-up axis direction (Z-axis) is adjusted within a predetermined angle range (for example, 0.5 ° or less) in the X-axis direction with respect to the Z-axis.

In this way, by tilting the c-axis of the seed crystal 31 by a predetermined angle β in the X-axis direction, the sapphire single crystal 32 grown using the seed crystal 31 is c c as shown in FIG. The axis is inclined at a predetermined angle β (in the range of 0.05 ° or more and 1.0 ° or less as described above) with respect to the normal nv direction of the main surface with the Z axis (the pulling direction) as the rotation axis. That is, a sapphire single crystal having a c-axis tilt angle on the main surface corresponding to the predetermined angle β can be obtained with the interval d. Thereby, all the step structures in the main surface of the obtained sapphire single crystal are in the same direction, and a plurality of sapphire single crystals without crystal defects can be obtained. Further, the deviation angle between the m-axis and the Z-axis is formed within the γ (0.5 °), and as shown in FIG. 12 (c), the c-axis and the Z-axis are formed within the α (90 ° ± 0.5 °). Is done. In addition, illustration of the neck is abbreviate | omitted in FIG.12 (c).

A clear crystal habit plane appears when the step structure appears on the c-plane, which is the main surface of the sapphire single crystal.

In the modification shown in FIGS. 11 and 12, a sapphire single crystal whose c-axis is inclined at a predetermined angle β with respect to the nv direction using a seed crystal 31 in which the c-axis is inclined in the a-axis direction by a predetermined angle β in advance. Although the case of growing 32 has been described, the present invention is not limited to this, and a sapphire single crystal may be grown using the seed crystal 33 shown in FIG.

The c-axis of the seed crystal 33 is adjusted so that the angle α formed with the Z-axis is within a predetermined range (for example, 90 ° ± 0.5 °) as shown in FIG. 13 (a). As shown, the c-axis is adjusted to be parallel to the Y-axis direction. On the other hand, the m-axis in the pulling direction (Z-axis) is perpendicular to the c-axis as shown in FIG. 13A, and the deviation angle γ from the Z-axis is Z-axis as shown in FIG. Is adjusted within a predetermined range (0.5 ° or less) in the X-axis direction (a-axis direction).

When the seed crystal 33 shown in FIG. 13 is used, the normal line of the side surface (end face) of the seed crystal 33 is positioned with a predetermined angle β shifted from the normal line of the partition plate 18 as shown in FIG.

Therefore, the shaft 13 or the crucible 5 is rotated by the control unit so that the normal line of the side surface (end face) of the seed crystal 33 is accurately positioned within the range of the predetermined angle β with respect to the normal line of the partition plate 18. To do. Thereby, a sapphire single crystal in which the c-axis is inclined by a predetermined angle β in a predetermined direction can be obtained.

Examples of the present invention will be described below, but the present invention is not limited to the following examples.

(Example)
In this example, the manufacturing apparatus 1 shown in FIG. 1 and a die without a notch 29 as shown in FIG. 2 were used, and a sapphire single crystal having a c-plane principal surface was grown and grown by the EFG method. Sixteen dies were prepared and arranged in parallel with a predetermined gap D in parallel with each other.

A granulated aluminum oxide raw material powder (99.99% aluminum oxide) was used as the aluminum oxide raw material, and a predetermined amount was charged into the crucible 5 containing the die 9 and melted to obtain an aluminum oxide melt. Argon gas was introduced into the growth vessel 3 as the atmospheric gas.

As the seed crystal, a substrate made of sapphire single crystal and having a thickness T of 2 mm was used, and the c-axis was a horizontal substrate along the plane direction of the main surface (a plane orthogonal to the crystal plane 28). The shape of the seed crystal was the substrate shown in FIG. Further, the seed crystal was arranged so that the plane direction of the seed crystal and the longitudinal direction of the die were orthogonal to each other at an angle of 90 ° as shown in FIG.

Using the seed crystal, 16 plate-shaped sapphire single crystals were pulled up and grown. The width of the sapphire single crystal was about 2 inches.

In all examples, examples 1 to 10 were performed, and in examples 1 to 4, the gap D was set to 0.34 times the thickness t of the die. On the other hand, in Examples 5 to 10, the gap D was set so as to satisfy Equation 3. The thickness t of the die is appropriately set as shown in Table 1 within the range of 3.3 mm to 4.5 mm in Examples 1 to 4, and appropriately set within Table 1 to within the range of 3.3 mm to 6.5 mm in Examples 5 to 10. Set as shown. Therefore, as shown in Table 1, the gap D was appropriately set in the range of 1.12 mm to maximum 1.53 mm in Examples 1 to 4, and appropriately set in the range of 1.20 mm to maximum 2.28 mm in Examples 5 to 10. However, the calculated value of the gap D was rounded off to the third decimal place.

When the gap d between the 16 flat-plate-shaped sapphire single crystals grown and grown was measured, the gap d was 0.33 times the maximum thickness tm of the 16 sheets in all Examples 1 to 10 or more and 0.67. It was confirmed that it was within the range of more than twice. The thickness tm in each example was equal to the die thickness t (as described above, the die thickness t was different in each example). Further, in Examples 5 to 10, it was also confirmed that the gap d satisfies the equation (4).

In each of Examples 1 to 10, it was confirmed that fluttering occurred in the 16 grown flat plate-shaped sapphire single crystals. As a result, the occurrence of flatting was prevented in all the examples. It was confirmed that sticking was eliminated.

Furthermore, in each of Examples 5 to 10, it was confirmed that there were no crystal parts such as line defects and crystal grain boundaries across all 16 sapphire single crystals.

(Comparative example)
Below, the comparative example of the said Example is demonstrated. In the comparative example, the description of the parts and processes that overlap with the examples is omitted or simplified, and the different parts and processes are described mainly.

The comparative example is different from the example in that the die thickness t is set to 4.5 mm, the gap D between the dies is set to 1.3 mm, the gap D is set to about 0.29 times the thickness t, and set to less than 0.33 times. This is the point.

When the gap d between the 16 flat-plate-shaped sapphire single crystals grown and measured was measured, the gap d was less than 0.33 times the maximum thickness tm of the 16 pieces, and was formed at about 0.29 times. Was confirmed. The thickness tm in the comparative example was equal to the die thickness t.

When it was confirmed that flattened 16 sapphire single crystals grown and grown were flattened, it was confirmed that flattening occurred in some gaps d.

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus of sapphire

single crystal

2, 32 Sapphire single crystal 3 Growth container 4 Lifting container 5 Crucible 6 Crucible drive part 7 Heater 8 Electrode 9 Die 10 Heat insulating material 11 Atmospheric gas introduction port 12 Exhaust port 13 Shaft 14 Shaft drive part 15 Gate Valve 16 Substrate inlet /

outlet

17, 31, 33 Seed crystal 18 Partition plate 19 Slit 20 Opening 21 Aluminum oxide melt 22 Aluminum oxide melt reservoir 23 Seed crystal notch 24 Seed crystal notch hole 25 Neck 26 Straight body part 27 Main surface 28 Crystal surface 29 Notch of partition plate 30 Slope T Thickness of seed crystal t Thickness of die tm Maximum thickness of sapphire single crystal D Between dies Gap between the d sapphire single crystal

Claims

A plurality of dies having slits and arranged in parallel in the longitudinal direction are accommodated in a crucible,
An aluminum oxide raw material is put into a crucible and heated, and the aluminum oxide raw material is melted in the crucible to prepare an aluminum oxide melt.
Form an aluminum oxide melt pool at the top of the slit through the slit,
A plurality of sapphire single crystals having a desired principal surface are grown by bringing the seed crystal into contact with the aluminum oxide melt above the slit and pulling up the seed crystal.
A method for producing a plurality of sapphire single crystals, characterized in that a plurality of sapphire single crystals are produced by setting a gap D between each die to be 0.33 times or more and 0.67 times or less of a die thickness t.
The gap D is within a range of 0.33 times to 0.67 times the thickness t, and

The method for producing a plurality of sapphire single crystals according to claim 1, wherein:
A plurality of sapphire single crystals are formed from a common seed crystal,
Furthermore, the gap | interval d between sapphire single crystals is set to 0.33 times or more and 0.67 times or less of the maximum thickness tm among the thickness of several sapphire single crystals, The several sapphire single crystal characterized by the above-mentioned.
The gap d is within a range of 0.33 to 0.67 times the thickness tm.

The plurality of sapphire single crystals according to claim 3, wherein:
5. The plurality of sapphire single crystals according to claim 3, wherein a deviation angle of a crystal axis of a main surface of the plurality of sapphire single crystals is within a range of 0.5 ° or less.