JP6057281B2 - Single crystal manufacturing apparatus and single crystal manufacturing method - Google Patents

Description

  The present invention relates to a single crystal manufacturing apparatus and a single crystal manufacturing method, and more particularly to a single crystal manufacturing apparatus and a single crystal manufacturing method that can be used in an edge-defined film-fed growth (EFG) method.

  An apparatus for producing a single crystal by the EFG method is known (for example, see Patent Document 1). In the single crystal manufacturing apparatus described in Patent Document 1, a crucible filled with raw materials, a die (die) standing in the crucible and having a slit, and a lid for closing the upper surface of the crucible except for the opening of the crucible have.

  In the single crystal manufacturing apparatus described in Patent Document 1, the seed crystal held in the seed crystal holder is brought into contact with the raw material melt accumulated on the upper surface of the mold by capillary action, and the single crystal is pulled up. Growing up.

  By the way, the positional relationship between the seed crystal and the mold defines the crystal direction in which the produced single crystal grows, and the crystal direction affects the performance of the single crystal. Had to be done carefully.

Japanese Patent Laying-Open No. 2006-312571 (pages 13-15, FIG. 6)

  However, when the seed crystal is small relative to the mold, it has been difficult to visually align the seed crystal and the mold. In addition, since the control mechanism that can finely adjust the position of the seed crystal is large, there is a problem that it is expensive and expensive.

  Then, an object of this invention is to provide the single-crystal manufacturing apparatus and single-crystal manufacturing method which enable position alignment with a seed crystal and a metal mold | die with a simple structure.

  In addition, the present invention provides a single crystal manufacturing apparatus and a single crystal manufacturing method capable of easily positioning a seed crystal and a mold and growing a high-quality single crystal when the EFG method is used. The purpose is to provide.

  A single crystal manufacturing apparatus according to the present invention includes a mold for holding a melt as a single crystal material on an upper surface portion, and a moving means for moving the seed crystal in contact with the melt held on the upper surface portion. The guide member further includes a guide member that contacts the seed crystal and defines the position of the seed crystal, the guide member having a guide reference portion parallel to the reference surface of the seed crystal, and the guide reference portion is one side of the upper surface portion of the mold. It is characterized by being parallel to.

  Furthermore, the single crystal manufacturing apparatus according to the present invention preferably further includes a fixing member that fixes the guide member to the moving means.

  Furthermore, the single crystal manufacturing apparatus according to the present invention preferably further includes a spring member for fixing the guide member to the seed crystal.

  A method for producing a single crystal according to the present invention includes a mold for holding a melt as a material for a single crystal on an upper surface portion, and a moving device for moving the seed crystal. A guide member having a guide reference portion parallel to the reference surface is brought into contact with the reference surface of the seed crystal, the guide reference portion is set to be parallel to one side of the upper surface portion of the mold, and held on the upper surface portion by the moving means. And a step of moving the seed crystal in contact with the melt.

  Furthermore, in the single crystal manufacturing method according to the present invention, it is preferable that the guide member is pulled up simultaneously with the seed crystal by the moving means.

  Furthermore, in the single crystal manufacturing method according to the present invention, it is preferable to further include a fixing member for fixing the guide member to the moving means.

  Furthermore, in the single crystal manufacturing method according to the present invention, it is preferable to further include a spring member for fixing the guide member to the seed crystal.

  In the single crystal manufacturing apparatus and the single crystal manufacturing method according to the present invention, the alignment between the seed crystal itself and the mold is not performed, but the first reference portion of the guide member fixed to the seed crystal and the mold are set. In addition, since the alignment with the second reference portion is performed, the seed crystal can be accurately positioned with respect to the mold.

  Moreover, in the single crystal manufacturing apparatus and the single crystal manufacturing method according to the present invention, the guide member fixed to the seed crystal is attached to the holder that holds the seed crystal, so there is no need to improve the apparatus, and the cost is low. The positioning accuracy between the seed crystal and the mold can be improved.

  Furthermore, in the single crystal manufacturing apparatus and the single crystal manufacturing method according to the present invention, since the guide member has at least one reference side parallel to the reference plane of the seed crystal, the reference side of the guide member and the mold Can be adjusted to the desired orientation. As a result, the seed crystal can be easily and accurately positioned in the desired crystal orientation indirectly with respect to the mold.

(A) is a top view of the single crystal manufacturing apparatus 1, (b) is a schematic cross-sectional view of the single crystal manufacturing apparatus 1, and (c) is a diagram showing a tip shape of the guide member. It is a perspective view of a part of the single crystal manufacturing apparatus 1 shown in FIG. It is a flowchart which shows an example of the manufacturing method of the single crystal by EFG method. It is a figure for demonstrating the other fixing method of the guide member to the seed crystal. It is the figure which showed typically the single crystal grown from the seed crystal. It is the figure which showed typically the case where a seed crystal and a metal mold | die shifted and were positioned. It is a figure which shows another guide member. It is a figure which shows another guide member.

  Hereinafter, a single crystal manufacturing apparatus and a single crystal manufacturing method will be described with reference to the drawings. However, it should be understood that the invention is not limited to the drawings or the embodiments described below.

  FIG. 1A is a top view of the single crystal manufacturing apparatus 1, FIG. 1B is a schematic cross-sectional view of the single crystal manufacturing apparatus 1, and FIG. 1C is a diagram showing the tip shape of the guide member. It is. FIG. 2 is a perspective view of a part of the single crystal manufacturing apparatus 1 shown in FIG.

  The single crystal manufacturing apparatus 1 includes a refractory outer frame 10, a refractory top lid 11 disposed on the refractory outer frame 10, a crucible 20 disposed in the refractory outer frame 10, and a gold disposed in the crucible 20. The mold 30 includes a moving mechanism 40 for moving the seed crystal 50 up and down with respect to the mold 30.

  The refractory outer frame 10 and the refractory top cover 11 are made of refractory bricks or the like and cover the periphery of the crucible 20. A heating member (heater or the like; not shown) for heating the crucible 20 is disposed around the refractory. Moreover, it is preferable that the refractory outer frame 10 and the refractory top lid 11 have heat retaining properties for suppressing a rapid temperature change of the heated crucible 20. The refractory top lid 11 is provided with an opening 12 so that the moving mechanism 40 can be moved up and down.

  The crucible 20 is made of a metal material having heat resistance capable of receiving the melt to be used, and has a shape such that a mold 30 having a predetermined size can be disposed therein.

  The mold 30 has a slit 31 for raising the melt by using a capillary phenomenon at an intermediate portion. The mold 30 is provided with a side surface 32 serving as a mark of a predetermined surface (for example, (100) plane) of a single crystal grown from the mold. The side surface 32 of the mold 30 and the slit 31 are arranged in parallel. In addition, the seed crystal 50 is positioned on the upper surface portion 30a of the mold 30 so as to come into contact with the melt that has risen due to the capillary phenomenon. Further, the width of the mold 30 is set to W2 mm (for example, 20 mm), and the width is set to t2 mm (for example, 10 mm).

  The moving mechanism 40 includes a holder 41 for holding the seed crystal 50, a reference surface 51 (for example, (100) surface) used in the seed crystal 50, and a side surface 32 (mold reference surface) of the mold 30 as a mark. Are arranged, a guide fixing member 43 for fixing the guide member 42 to the holder 41, a shaft 45, and the like. One end of the guide fixing member 43 is fixed to a part of the guide member 42, and the other end of the guide fixing member 43 passes through a through hole 46 provided in the shaft 45 and is fixed to the holder 41. The reference surface of the mold 30 can be set other than the side surface 32.

  As shown in FIG. 1C, the shape of the guide member 42 is a U-shape so that the seed crystal 50 can be easily fixed, the width is W1 mm (for example, 20 mm), and the width is t1 mm. (For example, 10 mm). In FIGS. 1 and 2, W1 = W2 and t1 = t2 are set. However, it is preferable to set 0 <W2 ≦ W1 and 0 <t2 ≦ t1. The shape of the opening 12 provided in the refractory top lid 11 is circular, and the diameter D (for example, 25 mm) is set to a size that allows the moving mechanism 40 with the guide member 42 to move up and down. .

  As shown in FIG. 1C, the guide member 42 includes a first guide reference portion 42-1 for contacting a reference surface 51 (for example, (100 surface)) of the seed crystal 50, and the mold 30. It has the 2nd guide reference part 42-2 for aligning with the side surface 32 (mold reference surface). By bringing the reference surface 51 of the seed crystal 50 into contact with the first guide reference portion 42-1, the positional relationship between the reference surface 51 of the seed crystal 50 and the second guide reference portion 42-2 is defined. It is comprised so that. In the case of FIG. 1C, the reference surface 51 of the seed crystal 50 and the second guide reference portion 42-2 are set in parallel.

  FIG. 3 is a flowchart showing an example of a method for producing a single crystal by the EFG method.

  First, the seed crystal 50 is attached to the holder 41 (S10), and the guide member 42 is fixed to the seed crystal 50 (S11). At this time, the reference surface 51 of the seed crystal 50 and the guide member are arranged such that the first guide reference portion 42-1 of the guide member 42 contacts the reference surface 51 (for example, (100 surface)) of the seed crystal 50. The positional relationship between the second guide reference portion 42-2 and 42 is defined.

  FIG. 4 is a diagram for explaining another method for fixing the guide member to the seed crystal 50.

  FIG. 4A shows a case where one reference plane 51 (for example, (100 plane)) of the seed crystal 50 is used. In this case, one reference surface 51 of the seed crystal 50 and the second guide are brought into contact with one reference surface 51 of the seed crystal 50 against the first guide reference portion 80-1 of the other guide member 80. It is defined so that the reference part 80-2 is parallel to the reference part 80-2.

  FIG. 4B shows a case where another reference plane 52 (for example, (110 plane)) of the seed crystal 50 is used. In this case, the other reference surface 52 of the seed crystal 50 and the second guide are brought into contact with the first guide reference portion 81-1 of the other guide member 81 so that the corner portion of the seed crystal 50 abuts. It is defined so that the reference portion 81-2 is parallel to the reference portion 81-2. In the case of FIG. 4B, the seed crystal 50 is in a state rotated slightly 45 degrees from the state of FIG.

  The shape of the guide member is a U-shape (guide member 42; see FIG. 1 (c)), a square shape (guide member 80; see FIG. 4 (a)), a hole shape into which a seed crystal can be inserted (guide) The member 81; see FIG. 4B) may be various. In addition, the positional relationship between the seed crystal and the second guide reference portion of the guide member can be variously defined according to the reference plane of the seed crystal to be used.

  Further, since the guide member is disposed in the vicinity of the crucible 20, the material of the guide member is excellent in heat resistance and is configured such that it does not deform or break even at high temperatures. Specifically, the guide member is made of a metal plate such as platinum, platinum-rhodium or iridium, or ceramics such as alumina or zirconia.

  Next, the mold 30 is placed in the crucible 20 and filled with a single crystal raw material (S12).

  Next, using the second guide reference portion 42-2 of the guide member 42 and the side surface 32 (die reference surface) of the mold 30, the second guide reference portion 42-2 and the mold 30 are visually observed. The position of the moving mechanism 40 is fixed so that the position of the side surface 32 (the mold reference surface) of the first and second side surfaces 32 coincides with each other and heated by a heater (not shown) (S13). The material dissolves when heated, and the solution enters the slit 31 of the mold 30, rises in the slit 31 by capillary action, and accumulates and is held on the upper surface portion 30 a of the mold 30. The positioning of the seed crystal 50 and the mold 30 is performed by adjusting a screw fastener (not shown) that fixes the moving mechanism 40 at the top, or by adjusting the position of the crucible 20 to which the mold 30 is fixed. It is done by adjusting.

  Next, the moving mechanism 40 is operated to lower the seed crystal 50, and the tip of the seed crystal 50 is brought into contact with the melt held on the upper part of the mold 30 (S14). At the contact portion of the melt that is in contact with the seed crystal 50, the temperature is lowered and a single crystal is formed.

  Next, the moving mechanism 40 is operated to continuously pull up the seed crystal 50 (S15). The rising speed for pulling up the seed crystal 50 can be appropriately selected according to the single crystal to be produced. By gradually pulling up the seed crystal 50, the single crystal grows while expanding in the longitudinal direction of the mold 30 around the seed crystal 50. Eventually, the mold 30 is expanded to a size slightly smaller than the width W2 of the mold 30, and thereafter grows with substantially the same width.

  After the single crystal grows to the desired size, the moving mechanism 40 is operated to increase the pulling speed or further increase the temperature, so that the single crystal and the melt held on the upper surface portion 30a of the mold 30 are melted. The liquid and the single crystal are separated (S16). After the temperature drop of the single crystal, the single crystal is cut into a predetermined size (S17), and the series of processes is completed.

  FIG. 5 is a diagram schematically showing a single crystal grown from a seed crystal.

  FIG. 5A shows a single crystal 90 grown from the seed crystal 50. 5A, the arrow a indicates the vertical direction from the upper surface portion 30a of the mold 30, the arrow b indicates the lateral t2 direction of the mold 30, and the arrow c indicates the width W2 of the mold 30. Shows direction. In the example of FIG. 5, the crystal is pulled up in the direction of arrow a to cut out the device.

  FIG. 5B shows a state in which the central portion of the single crystal separated from the melt of the mold 30 is further cut as a wafer 92. As described above, since the second guide reference portion 42-2 of the guide member 42 and the side surface 32 (mold reference surface) of the mold 30 can be easily aligned, the reference surface to be used in the seed crystal 50 is used. Thus, it is possible to accurately align the relationship between 51 and the reference surface 91 to be grown by the single crystal 90. Therefore, the performance of the wafer 92 cut from the single crystal 90 can be kept good.

  FIG. 6 is a diagram schematically showing the case where the seed crystal and the mold are positioned out of alignment.

  FIG. 6 shows a case where the seed crystal 50 is tilted by θ from the side surface 32 (mold reference surface) of the mold 30 in S14 of FIG. That is, a state in which a rotational deviation occurs around the axis by an angle θ about the arrow a is shown. Thus, when the seed crystal 50 is inclined by θ, the crystal direction of the single crystal grown from the seed crystal 50 is also shifted, and the performance of the manufactured single crystal may be deteriorated.

  The EFG method has a merit in that a single crystal having a desired orientation and shape can be grown from the beginning, so that post-processing such as cutting after growth can be simplified. However, if the orientation of the seed crystal deviates from the target orientation, an extra cutting process or the like is required for correction, and costs increase.

  For example, when a La3Ta0.5Ga5.3Al0.2O14 (LTGA) single crystal is grown using the EFG method and used as a surface acoustic wave (SAW) device, the surface wave velocity is 2720 m at θ = 0 (no deviation). / S and a frequency of 315 MHz. However, when θ = 10 °, the surface wave velocity is 2660 m / s and the frequency is 308 MHz, and when θ = 20 °, the surface wave velocity is 2520 m / s and the frequency is 292 MHz. For the surface wave velocity, a method (LFB-UMC method) in which a sample is irradiated with ultrasonic waves and calculated from a reflected waveform is used. Further, the above-mentioned frequency was obtained from frequency = surface wave velocity / interval between comb electrodes (= 8.64 μm) using an impedance analyzer with a comb electrode configured by a sample.

  When a Pb (Zr, Ti) 3 (PZT) single crystal is grown using the EFG method and used as a piezoelectric device, when θ = 0 (no deviation), the piezoelectric constant is 395 pC / N and the output is 100%. (Target value). However, when θ = 10 °, the piezoelectric constant is 387 pC / N and the output is 98% (when the output when θ = 0 is 100%), and when θ = 20 °, the piezoelectric constant is 364 pC / N and the output is 92% ( When the output when θ = 0 is 100%). The above piezoelectric constant indicates the piezoelectric constant in the direction of the arrow c when the rotational deviation occurs around the axis by the angle θ about the arrow a (see FIG. 5). The piezoelectric constant was measured by a resonance-antiresonance method (see JEITA EM-4501 standard) after forming an electrode of a predetermined size with a sample.

  FIG. 7 is a view showing still another guide member.

  Still another guide member 100 shown in FIG. 7 includes a guide plate 101 and spring plates 102 and 103. The guide plate 101 has a first guide reference portion 101-1, a second guide reference portion 101-2, and an opening 101-3. The two spring plates 102 and 103 are fixed to both end portions of the guide plate 101.

  After the tip of the seed crystal 50 protrudes from the opening 101-3, the reference plane used by the seed crystal 50 is brought into contact with the first guide reference portion 101-1, and the two spring plates 102 and 103 are brought into contact with each other. The guide plate 101 is fixed to the seed crystal 50 so as to sandwich the seed crystal 50. The user performs alignment using the second guide reference portion 101-2 and the side surface 32 (mold reference surface) of the mold 30 to thereby align the reference surface of the seed crystal 50 and the side surface 32 ( It is possible to accurately position the mold reference surface).

  FIG. 8 is a view showing still another guide member.

  Still another guide member 110 shown in FIG. 8 includes a first plate member 111, a second plate member 112, and a coupling member 113. The first plate member 111 includes a first guide reference portion 111-1, a second guide reference portion 111-2, and a first spring member 111-3. The second plate member 112 has a second spring member 112-3. When the first plate member 111 and the second plate member 112 are coupled by the coupling member 113 (for example, a bolt and a nut) in the moving mechanism 40, the first spring member 111-3 and the second spring member 112-3 are seed crystals 50. Is configured to be fixed.

  In the guide member 110 shown in FIG. 8, the first guide reference portion 111-1 is not brought into contact with the seed crystal 50, but a part of the moving mechanism 40 is brought into contact with the first guide reference portion 111-1. Thus, the positional relationship between a predetermined surface of the moving mechanism 40 and the second guide reference portion 111-2 is defined. Here, the positional relationship between the reference plane of the seed crystal 50 and the predetermined plane of the moving mechanism 40 is determined in advance, so that the positional relationship between the second guide reference portion and the reference plane of the seed crystal 50 is simplified. Is stipulated.

  Therefore, the user aligns using the second guide reference portion 111-2 and the side surface 32 (mold reference surface) of the mold 30 to thereby align the reference surface of the seed crystal 50 and the side surface of the mold 30. 32 (mold reference surface) can be easily positioned.

DESCRIPTION OF SYMBOLS 1 Single crystal manufacturing apparatus 20 Crucible 30 Mold 30a Upper surface part 32 Side surface (mold reference surface)
40 moving mechanism 41 holder 42, 80, 81, 100, 110 guide member 42-1, 80-1, 81-1, 101-1, 111-1 first guide reference part 42-2, 80-2, 81 -2, 101-2, 111-2 Second guide reference portion 45 Shaft 50 Seed crystal 51 Reference plane of seed crystal 90 Single crystal 91 Reference plane of single crystal

Claims (7)

A single crystal manufacturing apparatus comprising: a mold for holding a melt as a single crystal material on an upper surface portion; and a moving means for moving a seed crystal in contact with the melt held on the upper surface portion,
A holding member provided in the moving means and holding the seed crystal;
Wherein provided in a mobile unit, the seed crystal and in contact with, further comprising a guide member for defining the position of the seed crystal,
The guide member has a guide reference portion parallel to a reference surface of the seed crystal, and the guide reference portion is parallel to one side of the upper surface portion of the mold.
A single crystal manufacturing apparatus characterized by the above.   The single crystal manufacturing apparatus according to claim 1, further comprising a fixing member that fixes the guide member to the moving unit. The single crystal manufacturing apparatus according to claim 1, further comprising a spring member for fixing the seed crystal to the guide member . A method for producing a single crystal in a single crystal production apparatus, comprising: a mold for holding a melt as a single crystal material on an upper surface portion; and a moving means for moving a seed crystal,
Holding the seed crystal by a holding member provided in the moving means;
A guide member provided on the moving means and having a guide reference portion parallel to the reference surface of the seed crystal is brought into contact with the reference surface of the seed crystal,
The guide reference portion is set to be parallel to one side of the upper surface portion of the mold,
Moving the seed crystal in contact with the melt held on the upper surface by the moving means;
A method for producing a single crystal comprising steps.   The single crystal manufacturing method according to claim 4, wherein the guide member is pulled up simultaneously with the seed crystal by the moving means.   The single crystal manufacturing method according to claim 4, further comprising a fixing member that fixes the guide member to the moving means. The method for producing a single crystal according to any one of claims 4 to 6, further comprising a spring member for fixing the seed crystal to the guide member .

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