JPWO2010079826A1 - Single crystal manufacturing apparatus, single crystal manufacturing method, and single crystal - Google Patents

Abstract

A single crystal manufacturing apparatus, a single crystal manufacturing method, and a single crystal capable of obtaining an excellent quality single crystal with a relatively simple configuration are obtained. A single crystal production apparatus (1) is a single crystal production apparatus (1) for producing a single crystal by heating and melting a raw material held in a crucible (4) and then solidifying it from one direction. 3) and a crucible (4), a pedestal (2), and a heater (5). The pedestal (2) supports the ampoule (3). The heater (5) is for heating the ampoule (3) and the crucible (4). The material constituting the pedestal (2) has a thermal conductivity of 0.5 W / (m · K) or more and a value of the thermal conductivity of the single crystal to be formed. The material constituting the pedestal (2) has a light transmittance of 10% or less for a wavelength of 1600 nm or more and 2400 nm or less with respect to the material having a thickness of 4 mm.

Description

  The present invention relates to a single crystal manufacturing apparatus and a single crystal manufacturing method, and more specifically to a single crystal manufacturing apparatus and a single crystal manufacturing method including a quartz ampule holding a raw material container.

  Conventionally, a single crystal manufacturing apparatus and a single crystal manufacturing method using a vertical boat method such as a vertical Bridgman method (VB method) and a vertical temperature gradient solidification method (VGF method) are known. In such a single crystal production apparatus, a seed crystal is arranged at the bottom of the crucible to produce a single crystal, and a polycrystal as a raw material is placed inside the crucible, and these raw materials (above the seed crystal). The temperature gradient in the vertical direction is formed so that the raw material located at the melting point is higher than the melting point. Then, by pulling out the crucible downward (relatively lower temperature side) or by slowly cooling it while maintaining the temperature gradient, a single crystal is produced from the seed material as a starting point (for example, Japanese Patent Laid-Open No. 04-187585 (Patent Document 1) and JP-A-2005-298301 (Patent Document 2)).

  And in the said patent document 1, in order to improve the quality of the obtained single crystal, when forming a single crystal (solid phase) from the melted raw material (liquid phase), the solid-liquid interface becomes convex toward the liquid phase side. In addition, it is proposed that the structure of the pedestal (support) that supports the crucible be a laminated structure. Specifically, a structure in which thin plate members made of a material having high thermal conductivity and thin plate members made of a material having low heat conductivity are alternately stacked has been proposed. Further, high-purity carbon is cited as an example of a material having high thermal conductivity, and quartz is cited as an example of a material having low thermal conductivity.

  Patent Document 2 discloses the following configuration for the purpose of preventing breakage during crucible conveyance in the single crystal production apparatus and preventing occurrence of defects during single crystal production. That is, the crucible is held by a holding tool, and a holding part that can be held by a hand or a jig is formed on the holding tool. In the single crystal manufacturing apparatus, the holder is mounted on a pedestal (stage) that can be moved up and down. The holder holds the crucible in close contact with the outer periphery of the crucible. Examples of the material for the crucible include boron nitride (BN), and examples of the material for the holder include quartz, silicon carbide, silicon nitride, carbon, and molybdenum. In addition, in patent document 2, it is not specified in particular about the material of a base.

Japanese Patent Laid-Open No. 04-187585 JP-A-2005-298301

  The conventional single crystal manufacturing apparatus described above has the following problems. That is, since the pedestal has a laminated structure as described above, the structure is complicated, and the manufacturing cost of the device increases. In addition, since materials with different thermal conductivity and thermal expansion coefficient are combined, the pedestal may be deformed or damaged, or a discontinuous temperature distribution may occur at the part in contact with the pedestal, resulting in reduced crystal quality. There is.

  Further, in the conventional single crystal manufacturing apparatus described above, thermal expansion due to heat treatment during single crystal manufacturing is performed on the raw material holding unit composed of the crucible (or crucible and holder (ampoule)) and the pedestal that supports the raw material holding unit. No consideration has been given to. For this reason, for example, when using materials having greatly different coefficients of thermal expansion between the holder and the pedestal, the pedestal or the holder is damaged due to a difference in dimensional change due to thermal expansion due to a temperature change in heat treatment during single crystal production. There is a case. Further, such damage to the constituent devices also adversely affects the quality of the obtained single crystal.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a single crystal manufacturing apparatus and a single crystal capable of obtaining a single crystal of excellent quality with a relatively simple configuration. It is to provide a method for producing crystals.

  Another object of the present invention is to provide a single crystal manufacturing apparatus and a single crystal manufacturing method capable of preventing damage to the single crystal manufacturing apparatus due to heat treatment during single crystal manufacturing and obtaining a single crystal of excellent quality. Is to provide.

  In the single crystal manufacturing apparatus according to the present invention, after the raw material held in the raw material holding vessel is heated and dissolved, the vertical Bridgman method (VB method) or the vertical temperature gradient solidification method (VGF method) is used. A single crystal manufacturing apparatus for manufacturing a single crystal by solidifying from one direction, comprising a raw material holding container, a pedestal, and a heater. The pedestal supports the raw material holding container. The heater is for heating the raw material holding container. The material constituting the pedestal has a thermal conductivity of 0.5 W / (m · K) or more and a value of the thermal conductivity of the single crystal to be formed. The material constituting the pedestal has a light transmittance of 10% or less for a wavelength of 1600 nm to 2400 nm with respect to the material having a thickness of 4 mm. Further, it is more preferable that the transmittance of the material constituting the pedestal is 5% or less.

  In this way, the material constituting the pedestal is in a molten state in the raw material holding container by adopting a relatively simple configuration in which the material is opaque to light having a wavelength of 1600 nm to 2400 nm. When solidifying from one direction (specifically from the pedestal side), it is possible to suppress heat radiation from the raw material holding container to the outer peripheral side through the pedestal due to infrared rays or the like. As a result, the flow of heat transmitted from the melted raw material to the pedestal can be guided in a direction (downward) toward the lower surface of the pedestal. As a result, the boundary portion (solid-liquid interface) between the melted raw material (liquid phase) and the portion (solid phase) where the raw material has solidified into a single crystal is made flat or convex toward the liquid phase side. It becomes possible. For example, the raw material holding container is connected to the enlarged diameter portion whose width gradually increases from the pedestal side and the enlarged diameter portion, and the rate of change in width is smaller than that of the enlarged diameter portion (for example, the width is substantially constant). When the solid-liquid interface is located at the enlarged diameter portion, the solid-liquid interface is flattened as described above. Or a convex shape toward the liquid phase. As a result, generation of crystal defects can be suppressed in the obtained single crystal.

  In addition, the lower limit of the value of the thermal conductivity of the material constituting the pedestal is set to 0.5 W / (m · K) because the raw material is less than 0.5 W / (m · K). This is because the cooling efficiency of the raw material in the holding container is lowered and it is difficult to make the solid-liquid interface flat or convex to the liquid phase side as described above. Further, the upper limit of the value of the thermal conductivity is set as the value of the thermal conductivity of the single crystal to be formed when the thermal conductivity of the material constituting the pedestal exceeds the value of the thermal conductivity of the single crystal. This is because it is difficult to make the solid-liquid interface flat as described above or convex to the liquid phase side. In addition, the wavelength of light defining the transmittance of the material constituting the pedestal is set to 1600 nm or more and 2400 nm or less because the wavelength of light generated from the heater as a heat source during single crystal growth corresponds to the above wavelength range. is there. Further, the transmittance is set to 10% or less, and if the transmittance is 10% or less, the material of the pedestal can be regarded as substantially opaque with respect to light having the above-described wavelength. This is because it is possible to reliably obtain the effect. Further, the more preferable range of the transmittance is set to 5% or less. If the transmittance is 5% or less, the material of the subject may be more reliably regarded as opaque with respect to the light having the wavelength described above. This is because the effects of the present invention can be obtained more reliably.

  A method for producing a single crystal according to the present invention is a method for producing a single crystal using the above-described apparatus for producing a single crystal, and the following steps are performed. That is, a step of inserting seed crystal and single crystal source materials into the source holding container is performed. And the process which fuse | melts a raw material by heating a raw material holding | maintenance container with a heater is implemented. Furthermore, the process which manufactures a single crystal by gradually solidifying the fuse | melted raw material from the seed crystal side is implemented.

  In this way, when the polycrystalline raw material piece is once melted (heating step (S30)) and then subjected to a solidification process (crystal growth step (S40)), the heat transferred from the molten raw material to the pedestal Can be guided in a direction (downward) toward the lower surface of the pedestal. As a result, the boundary portion (solid-liquid interface) between the melted raw material (liquid phase) and the portion (solid phase) where the raw material has solidified into a single crystal can be made flat or convex toward the liquid phase side. It becomes possible. For example, the raw material holding container is connected to the enlarged diameter portion whose width gradually increases from the pedestal side and the enlarged diameter portion, and the rate of change in width is smaller than that of the enlarged diameter portion (for example, the width is substantially constant). When the solid-liquid interface is located at the enlarged diameter portion, the solid-liquid interface is flattened as described above. Or a convex shape toward the liquid phase. As a result, generation of crystal defects can be suppressed in the obtained single crystal.

The single crystal according to the present invention is a single crystal made of gallium arsenide containing silicon, and has a single crystal widened portion that gradually increases in width from the seed crystal side, and a width change that continues to the single crystal widened portion. A straight body portion whose rate is smaller than that of the single crystal expanded portion. The average silicon concentration in the plane perpendicular to the growth axis direction of the single crystal is 1 × 10 ¹⁷ cm ⁻³ or more and 7 × 10 ¹⁷ cm ⁻³ or less at the boundary between the single crystal expanded portion and the straight body portion. The average value of dislocation density is 0 cm ⁻² or more and 2000 cm ⁻² or less.

  Thus, by controlling the dislocation density in the above range at the boundary (shoulder portion) between the single crystal enlarged diameter portion and the straight body portion, the generation of lineage in the straight body portion can be effectively suppressed.

  A single crystal production apparatus according to the present invention is a single crystal production apparatus for producing a single crystal by heating and melting a raw material held in a raw material container and then solidifying it from one direction. And a quartz ampule for holding the raw material container therein, a pedestal for supporting the quartz ampule, and a heater for heating the raw material container. The thermal expansion coefficient of the material constituting at least the portion in contact with the quartz ampule in the pedestal is a value included within a range of ± 50% of the thermal expansion coefficient of quartz constituting the quartz ampule.

  In this way, when the raw material container is heated by a heater to produce a single crystal, and the temperature of the raw material container is lowered in order to obtain a single crystal by solidifying the raw material that has become a liquid phase by heating. When this is done, the difference in thermal expansion between the quartz ampule and the pedestal can be made sufficiently small. As a result, it is possible to suppress the occurrence of a problem that the quartz ampule or the base is damaged due to the difference in the thermal expansion amount.

The thermal expansion coefficient of the material constituting the part that contacts the quartz ampule in the pedestal is within ± 50% of the thermal expansion coefficient of quartz (0.5 to 1.5 times the thermal expansion coefficient of quartz). The reason is as follows. That is, when the thermal expansion coefficient of the material is out of the above range, a large difference occurs between the quartz ampule and the portion of the pedestal with respect to the displacement due to the thermal expansion during the heat treatment for forming the single crystal. As a result, a large stress is applied to the contact portion between the quartz ampule and the pedestal, and the quartz ampule (or pedestal) is damaged with a high probability. The thermal expansion coefficient of quartz constituting the quartz ampoule is about, for example, as described in “Shin-Etsu Quartz Co., Ltd. Technical Guide Chemical Physical Properties PC-TG-CFC-004, 2005, 10, 01 Edition”. 5 × 10 ⁻⁷ (K ⁻¹ ), and ± 50% corresponds to a range of about 2.5 × 10 ⁻⁷ (K ⁻¹ ) to about 7.5 × 10 ⁻⁷ (K ⁻¹ ). To do.

  A method for producing a single crystal according to the present invention is a method for producing a single crystal using the single crystal production apparatus, and includes the following steps. That is, first, a step of inserting seed crystal and single crystal source materials into the source container is performed. And the process which fuse | melts a raw material substance by heating a raw material container with a heater is implemented. Furthermore, the process which manufactures a single crystal by gradually solidifying the fuse | melted raw material from the seed crystal side is implemented.

  In this way, there is no significant difference in the coefficient of thermal expansion between the quartz ampoule and the pedestal when the raw material is melted once and then heat-treated to solidify, so that problems such as damage to the quartz ampoule and pedestal occur. Can be suppressed. As a result, the deterioration of the quality of the single crystal due to the damage of the quartz ampule or the pedestal can be suppressed, so that a high quality single crystal can be obtained stably.

  According to the present invention, an excellent quality single crystal can be obtained by a single crystal manufacturing apparatus having a relatively simple configuration.

  Further, according to the present invention, it is possible to prevent breakage due to heat treatment in a single crystal production apparatus and obtain a single crystal of excellent quality.

It is a schematic diagram which shows Embodiment 1 of the single-crystal manufacturing apparatus by this invention. It is a flowchart which shows the single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. It is a schematic diagram for demonstrating the use condition of the single crystal manufacturing apparatus shown in FIG. It is an enlarged schematic diagram which shows the 1st modification of the single crystal manufacturing apparatus shown in FIG. It is an enlarged schematic diagram which shows the 2nd modification of the single crystal manufacturing apparatus shown in FIG. It is an enlarged schematic diagram which shows the 3rd modification of the single crystal manufacturing apparatus shown in FIG. It is a schematic diagram which shows Embodiment 2 of the single crystal manufacturing apparatus by this invention. It is an enlarged schematic diagram which shows the 1st modification of the single crystal manufacturing apparatus shown in FIG. It is an enlarged schematic diagram which shows the 2nd modification of the single crystal manufacturing apparatus shown in FIG. It is an enlarged schematic diagram which shows the 3rd modification of the single crystal manufacturing apparatus shown in FIG. It is a schematic diagram which shows the single crystal manufactured using the single crystal manufacturing apparatus by this invention. It is a schematic diagram which shows Embodiment 4 of the single crystal manufacturing apparatus by this invention. It is a flowchart which shows the single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. It is a schematic diagram for demonstrating the use condition of the single crystal manufacturing apparatus shown in FIG. It is an enlarged schematic diagram which shows the 1st modification of the single crystal manufacturing apparatus shown in FIG. It is an expansion schematic diagram which shows the 2nd modification of the single crystal manufacturing apparatus shown in FIG. FIG. 13 is a partial enlarged schematic view showing a third modification of the single crystal manufacturing apparatus shown in FIG. 12. It is a schematic diagram which shows Embodiment 5 of the single crystal manufacturing apparatus by this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a schematic diagram showing a first embodiment of a single crystal manufacturing apparatus according to the present invention. A single crystal manufacturing apparatus according to the present invention will be described with reference to FIG.

  Referring to FIG. 1, a single crystal manufacturing apparatus 1 includes a pedestal 2, an ampule 3 mounted on the pedestal 2, a crucible 4 held inside the ampoule 3, and a raw material filled in the crucible 4. And a heater 5 for heating. The pedestal 2 is a cylindrical body whose planar shape is, for example, a circular shape, and has a mortar-shaped inclined portion 12 on the upper surface, and a concave portion 11 located on the inner peripheral side of the inclined portion 12 (approximately the center of the upper surface). And have. The planar shape of the recess 11 is, for example, a circular shape, and the width of the recess 11 is substantially constant in the depth direction. The inclined portion 12 is configured to be inclined (relative to the bottom wall of the pedestal 2) so that the distance from the bottom wall of the pedestal 2 increases from the upper end of the recess 11 toward the outer peripheral side of the pedestal 2. As a material of the base 2, for example, quartz can be used. Moreover, as a material of the base 2, it is preferable that the heat conductivity is 0.5 W / (m · K) or more and not more than the value of the heat conductivity of the single crystal to be formed. Here, as a specific example of “single crystal to be formed and its thermal conductivity”, for example, when the material of the single crystal to be formed is gallium arsenide (GaAs), its thermal conductivity is about 50 W / (m · K) When the material of the single crystal to be formed is indium phosphide (InP), its thermal conductivity is about 70 W / (m · K). These values of thermal conductivity are values at room temperature. Moreover, it is preferable that the material which comprises the base 2 has the transmittance | permeability of the light whose wavelength with respect to the said material with a thickness of 4 mm is 1600 nm or more and 2400 nm or less to 10% or less. Further, the transmittance is more preferably 5% or less. Here, the transmittance is a ratio between the intensity of the light incident on the material and the intensity of the light transmitted through the material having a thickness of 4 mm ((intensity of transmitted light) / (intensity of incident light) × 100. ).

  Further, the material of the base 2 is a material having a thermal expansion coefficient that is within a range of ± 50% of the thermal expansion coefficient of quartz constituting the ampule 3, and is sufficient at a heat treatment temperature for forming a single crystal. It is preferable to use a material having strength (for example, a melting point higher than the heat treatment temperature). For example, it is preferable to use opaque quartz as the material of the base 2.

  The ampule 3 mounted on the pedestal 2 is a quartz ampule (quartz ampule), and its shape is substantially cylindrical. The bottom surface of the ampoule 3 has a shape that can be mounted on the upper surface of the pedestal 2 described above. More specifically, the ampoule 3 is housed in the recess 11 of the pedestal 2, and has a small-diameter portion 21 whose planar shape is substantially circular, and continues on the small-diameter portion 21, along the inclined portion 12 of the pedestal 2. And a straight body portion 23 that is continuous with the enlarged diameter portion 22 and has a planar shape that is, for example, a circular shape similar to the base 2 and has a substantially constant width. In addition, the width | variety of the straight body part 23 may become large gradually as it leaves | separates from the enlarged diameter part 22, and the change rate of the width | variety may be changed in the middle of the straight body part 23. FIG. In other words, the width of the straight body portion 23 is changed to some extent as well as when the width is substantially constant as described above (the side wall of the straight body portion 23 is slightly inclined with respect to the outer peripheral side wall of the base 2. )In some cases. Further, the straight body portion 23 only needs to have a width change rate in the straight body portion 23 smaller than a width change rate in the enlarged diameter portion 22. Here, the width means a width in a direction (horizontal direction) perpendicular to the extending direction of the ampoule 3. The width of the small diameter portion 21 is substantially constant at an arbitrary position in the depth direction. The small diameter portion 21 has a shape along the inner wall of the concave portion 11 of the base 2. The inclination angle of the side wall (relative to the side wall of the straight body portion 23) in the enlarged diameter portion 22 of the ampoule 3 is substantially the same as the inclination angle of the inclined portion 12 of the base 2 (relative to the outer peripheral side wall of the base 2).

  The crucible 4 held inside the ampoule 3 basically has a shape along the inner peripheral surface of the ampoule 3. Specifically, a small-diameter portion 31 of the crucible 4 housed inside the small-diameter portion 21 of the ampoule 3 is formed at the center of the bottom of the crucible 4. The planar shape of the small diameter portion 31 is, for example, a circular shape. An enlarged diameter portion 32 of the crucible 4 is formed from the upper end portion of the small diameter portion 31 along the enlarged diameter portion 22 of the ampoule 3. The straight body portion 33 is formed so as to continue to the upper end of the enlarged diameter portion 32. The straight barrel portion 33 of the crucible 4 is basically disposed along the inner peripheral surface of the straight barrel portion 23 of the ampoule 3. And the heater 5 is arrange | positioned so that the outer periphery of the base 2, the ampoule 3, and the crucible 4 may be enclosed.

  Next, a single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. 1 will be described. FIG. 2 is a flowchart showing a single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. As shown in FIG. 2, in the method for producing a single crystal according to the present invention, a seed crystal preparation step (S10) is first performed. Specifically, a single-crystal piece serving as a seed crystal is inserted into the small-diameter portion 31 of the crucible 4 shown in FIG.

  Next, as shown in FIG. 2, a raw material preparation step (S20) is performed. Specifically, a predetermined amount of polycrystalline raw material pieces to be single crystal raw materials are put into the crucible 4. As the composition of the single crystal small piece and the polycrystalline raw material piece, any crystalline material can be used. For example, gallium arsenide (GaAs) containing silicon can be used as the composition.

  Next, a heating step (S30) is performed as shown in FIG. Specifically, by energizing the heater 5 shown in FIG. 1, the polycrystalline raw material pieces inside the crucible 4 are heated to a molten state. At this time, the heating condition by the heater 5 is adjusted so that the single crystal piece disposed in the small diameter portion 31 of the crucible 4 does not melt.

  Next, as shown in FIG. 2, a crystal growth step (S40) is performed. Specifically, by moving the base 2, the ampoule 3 and the crucible 4 to the lower side of FIG. 1 (in the direction indicated by the arrow 7 in FIG. 3) with respect to the heater 5, using a lifting device (not shown), The temperature of the melted polycrystalline raw material is gradually lowered from the vicinity of a single crystal piece (seed crystal) disposed inside the small diameter portion 31 of the crucible 4. As a result, the heated and melted raw material gradually solidifies (crystallizes) from the vicinity of the seed crystal. The solidified part is a single crystal. Then, by gradually pulling out the pedestal 2, the ampule 3 and the crucible 4 from the inner peripheral side of the heater 5 to the lower side, the melted raw material is gradually added from the lower side of the crucible 4 (that is, in the vicinity of the seed crystal). It will crystallize. In this way, a single crystal can be grown. The pedestal 2, the ampoule 3 and the crucible 4 may be fixed and the heater 5 may be moved upward, or the heaters while maintaining the predetermined temperature distribution with the positions of the crucible 4 and the heater 5 fixed. The temperature of 5 may be lowered. When the melted raw material is completely solidified, the “cooling step (S50) is performed. In the cooling step (S50), the temperature of the heater 5 is lowered, for example, to cool the single crystal inside the crucible 4 to room temperature. To do.

  At this time, by using, for example, opaque quartz as the material of the pedestal 2, heat is transmitted from the crucible 4 and the ampoule 3 to the outer peripheral side through the pedestal 2 by thermal radiation such as infrared rays through the pedestal 2. Can be suppressed. For this reason, the flow of heat transmitted from the melted raw material to the pedestal 2 can be guided in the direction toward the lower surface of the pedestal 2 (downward), more preferably in the direction toward the recess 11 of the pedestal 2. As a result, as shown in FIG. 3, the solid-liquid interface 17, which is the boundary between the molten material 16 and the single crystal 15 (solid phase) grown by solidification of the raw material, is flattened in the enlarged diameter portion of the crucible 4. Alternatively, the shape can be convex toward the molten material 16 side. As a result, generation of crystal defects can be suppressed in the obtained single crystal 15. FIG. 3 is a schematic diagram for explaining a use state of the single crystal manufacturing apparatus shown in FIG.

  FIG. 4 is an enlarged schematic view showing a first modification of the single crystal manufacturing apparatus shown in FIG. With reference to FIG. 4, the 1st modification of the single-crystal manufacturing apparatus 1 shown in FIG. 1 is demonstrated.

  Referring to FIG. 4, the first modification of the single crystal manufacturing apparatus according to the present invention basically has the same configuration as that of single crystal manufacturing apparatus 1 shown in FIG. 1 is different from the single crystal manufacturing apparatus 1 shown in FIG. 1 in that an uneven portion 13 as an anti-adhesion layer is formed on the surface. In this way, it is possible to suppress the occurrence of trouble such that the ampoule 3 and the pedestal 2 adhere to the inclined portion 12 when a single crystal is formed. In addition, the surface roughness in the uneven | corrugated shaped part 13 of the inclination part 12 can be 0.5 or more and 9.5 or less in Ra (refer JISB0601-1994). The surface roughness is more preferably 1.5 or more and 7.0 or less in Ra, and further preferably 2.5 or more and 4.5 or less in Ra. When Ra is too small, the contact area increases and the ampoule 3 and the pedestal 2 are likely to stick to each other. On the other hand, if Ra is too large, the number of convex portions that come into contact with the ampoule 3 is reduced, and the contact pressure to the individual convex portions is increased, and sticking is likely to occur. That is, the surface roughness is preferably 0.5 to 9.5, more preferably 1.5 to 7.0, and even more preferably 2.5 to 4.5 in terms of Ra.

  FIG. 5 is an enlarged schematic view showing a second modification of the single crystal manufacturing apparatus shown in FIG. With reference to FIG. 5, the 2nd modification of the single-crystal manufacturing apparatus 1 shown in FIG. 1 is demonstrated.

  Referring to FIG. 5, the second modification of the single crystal manufacturing apparatus basically has the same configuration as single crystal manufacturing apparatus 1 shown in FIG. 1, but prevents sticking to inclined portion 12 of pedestal 2. The processing layer 19 is different from the single crystal manufacturing apparatus 1 shown in FIG. This anti-adhesion treatment layer 19 is a layer made of a material having a relatively low reactivity with quartz that is a material constituting the ampoule 3 (as compared to a case where quartz is in contact with each other). A film or the like can be used. The film thickness of the anti-sticking treatment layer 19 is 10 μm or more and 1 mm or less, more preferably 50 μm or more and 500 μm or less, and further preferably 100 μm or more and 300 μm or less. By adopting such a configuration, the same effect as that of the single crystal manufacturing apparatus shown in FIG. 4 can be obtained.

  FIG. 6 is an enlarged schematic view showing a third modification of the single crystal manufacturing apparatus shown in FIG. With reference to FIG. 6, the 3rd modification of the single-crystal manufacturing apparatus shown in FIG. 1 is demonstrated.

  Referring to FIG. 6, the single crystal manufacturing apparatus basically has the same configuration as single crystal manufacturing apparatus 1 shown in FIG. 1, but between surface 14 of inclined portion 12 of pedestal 2 and ampoule 3. The point in which the mold release agent 20 is arrange | positioned differs from the single crystal manufacturing apparatus 1 shown in FIG. Even with this configuration, it is possible to prevent sticking between the base 2 and the ampoule 3 as in the single crystal manufacturing apparatus shown in FIG. As the release agent 20, for example, SiC powder, alumina powder, or the like can be used. The particle size of the release agent 20 is preferably 0.1 μm or more and 20 μm or less, more preferably 0.3 μm or more and 15 μm or less, and further preferably 0.5 μm or more and 10 μm or less.

(Embodiment 2)
FIG. 7 is a schematic diagram showing a second embodiment of the single crystal manufacturing apparatus according to the present invention. A second embodiment of the single crystal manufacturing apparatus according to the present invention will be described with reference to FIG.

  Referring to FIG. 7, single crystal manufacturing apparatus 1 basically has the same structure as single crystal manufacturing apparatus 1 shown in FIG. 1, but crucible 4 is directly mounted on pedestal 2 ( 1 is different from the single crystal manufacturing apparatus 1 of FIG. 1 in that the ampule 3 shown in FIG. Specifically, in the single crystal manufacturing apparatus 1 shown in FIG. 7, the small diameter portion 31 of the crucible 4 is disposed inside the recess 11 of the base 2. Moreover, the diameter-expanded part 32 of the crucible 4 is arrange | positioned so that the inclined part 12 of the base 2 may be contacted. By adopting such a configuration, the same effect as that of the single crystal manufacturing apparatus 1 shown in FIG. 1 can be obtained.

  FIG. 8 is an enlarged schematic view showing a first modification of the single crystal manufacturing apparatus shown in FIG. With reference to FIG. 8, the 1st modification of the single-crystal manufacturing apparatus 1 shown in FIG. 7 is demonstrated.

  Referring to FIG. 8, the first modification of the single crystal production apparatus according to the present invention basically has the same configuration as single crystal production apparatus 1 shown in FIG. 7, but the single crystal production apparatus shown in FIG. Similar to the crystal manufacturing apparatus 1, it is different from the single crystal manufacturing apparatus 1 shown in FIG. 7 in that a concavo-convex shape portion 13 as an adhesion preventing layer is formed on the surface of the inclined portion 12 of the pedestal 2. In this way, it is possible to suppress the occurrence of troubles such as the crucible 4 and the pedestal 2 being fixed at the inclined portion 12 when forming a single crystal. In addition, the surface roughness in the uneven | corrugated shaped part 13 of the inclination part 12 can be 0.5 or more and 9.5 or less in Ra (refer JISB0601-1994). The surface roughness is more preferably 1.5 or more and 7.0 or less in Ra, and further preferably 2.5 or more and 4.5 or less in Ra. If the unevenness of the inclined portion is too small, the contact area increases, and the crucible 4 and the pedestal 2 are likely to adhere to each other. On the other hand, if Ra is too large, the number of convex portions that come into contact with the crucible 4 is reduced, and the contact pressure to the individual convex portions is increased, and sticking is likely to occur. That is, the surface roughness is preferably 0.5 to 9.5, more preferably 1.5 to 7.0, and even more preferably 2.5 to 4.5 in terms of Ra.

  FIG. 9 is an enlarged schematic view showing a second modification of the single crystal manufacturing apparatus shown in FIG. With reference to FIG. 9, the 2nd modification of the single-crystal manufacturing apparatus 1 shown in FIG. 7 is demonstrated.

  Referring to FIG. 9, the second modification of the single crystal manufacturing apparatus basically has the same configuration as that of single crystal manufacturing apparatus 1 shown in FIG. 7, but prevents sticking to inclined portion 12 of pedestal 2. The point where the treatment layer 19 is formed is different from the single crystal manufacturing apparatus 1 shown in FIG. This anti-adhesion treatment layer 19 is a layer made of a material whose reactivity with the material constituting the crucible 4 is relatively lower than the material constituting the base 2. For example, when the crucible 4 is quartz, An alumina film or the like can be used. The film thickness of the anti-sticking treatment layer 19 is 10 μm or more and 1 mm or less, more preferably 50 μm or more and 500 μm or less, and further preferably 100 μm or more and 300 μm or less. By adopting such a configuration, the same effect as that of the single crystal manufacturing apparatus shown in FIG. 8 can be obtained.

  FIG. 10 is an enlarged schematic view showing a third modification of the single crystal manufacturing apparatus shown in FIG. With reference to FIG. 10, the 3rd modification of the single-crystal manufacturing apparatus shown in FIG. 7 is demonstrated.

  Referring to FIG. 10, the single crystal manufacturing apparatus basically has the same configuration as single crystal manufacturing apparatus 1 shown in FIG. 7, but between surface 14 of inclined portion 12 of pedestal 2 and crucible 4. The point in which the mold release agent 20 is arrange | positioned differs from the single crystal manufacturing apparatus 1 shown in FIG. Even with this configuration, it is possible to prevent sticking between the base 2 and the crucible 4 as in the single crystal manufacturing apparatus shown in FIG. As the release agent 20, for example, SiC powder, alumina powder, or the like can be used. The particle size of the release agent 20 is preferably 0.1 μm or more and 20 μm or less, more preferably 0.3 μm or more and 15 μm or less, and further preferably 0.5 μm or more and 10 μm or less.

(Embodiment 3)
FIG. 11 is a schematic view showing a single crystal manufactured using the single crystal manufacturing apparatus according to the present invention. A single crystal 40 according to the present invention will be described with reference to FIG.

Referring to FIG. 11, single crystal 40 made of gallium arsenide is a single crystal manufactured using the single crystal manufacturing apparatus shown in FIG. 1, and is basically a crucible of single crystal manufacturing apparatus 1 of FIG. 4 has the same outer shape as the inner shape. That is, a seed crystal that is a base point for crystal growth is located at the lower end of the single crystal 40 in FIG. 11, and a single crystal enlarged portion whose diameter gradually increases from the lower end, and the single crystal enlarged portion. And a straight body portion (body portion) in which the rate of change in width (diameter) is smaller than that of the single crystal enlarged portion. A boundary portion between the single crystal enlarged diameter portion and the straight body portion is referred to as a shoulder portion 41. Further, the central part in the length direction (crystal growth direction) of the straight body part is a body part center 42, and the upper end of the straight body part is a tail part 43. The average concentration of silicon in the plane perpendicular to the growth axis direction of the single crystal 40 is 1 × 10 ¹⁷ cm ⁻³ or more and 7 × 10 ^{17 at} the boundary (shoulder portion 41) between the single crystal expanded portion and the straight body portion. cm ⁻³ or less, and the average value of dislocation density is from 0 cm ^{−2 to} 2000 cm ⁻² .

  Here, when the single crystal 40 is formed using the single crystal manufacturing apparatus 1 according to the present invention, when the solid-liquid interface is located in the enlarged diameter portion, the solid-liquid interface is flattened toward the liquid phase as described above. It can be a convex shape. As a result, it is possible to suppress the occurrence of crystal defects in the obtained single crystal 40. In other words, the inventor greatly increases the dislocation density at the boundary (shoulder portion 41) between the single crystal enlarged diameter portion and the straight body portion by controlling the solid-liquid interface shape of the enlarged diameter portion to “flat or convex shape”. We found that it can be reduced. As a result, the dislocation density at the shoulder 41 can be reduced even at a low silicon concentration. As a result, it has been found that the number of defects such as lineage in the crystal body (that is, a part that becomes a product such as a wafer) is greatly reduced. Lineage means a defect formed by locally gathering high concentration of dislocations, and a part where the defect exists cannot be a product.

Here, in the single crystal 40 having a silicon concentration of a certain amount or less, there is a problem that lineage is likely to occur. However, when the dislocations of the shoulder portion 41 are less than a certain density, the straight body portion (the product body portion) The inventor of the present application has found for the first time that the generation of lineage in the crystal body) is suppressed. Furthermore, a crystal with a large ratio of “length of straight body / diameter of straight body” (ratio of length of straight body to diameter), specifically, “length of straight body / length of straight body” It has been found that the present invention can obtain a more remarkable effect in a crystal having a ratio of “diameter” of 1.5 or more. Further, in a crystal having a low silicon concentration of 1 × 10 ¹⁷ cm ^{−3 to} 7 × 10 ¹⁷ cm ⁻³ , pits (minute pits) due to dislocations may occur in the wafer polishing process. It has been found that such pits are remarkably reduced when the density is below a certain density (2000 cm ⁻² ).

Specifically, when the silicon concentration at the shoulder 41 is 1 × 10 ¹⁷ cm ^{−3 to} 7 × 10 ¹⁷ cm ⁻³ (note that the silicon concentration is determined according to the product design of the single crystal). dislocation density 2000 cm ^-2 or less, more preferably 1500 cm ^-2 or less, more preferably at 1000 cm ^-2 or less, lineage occurs in the straight body portion is suppressed, high yield was obtained. Further, a favorable effect is obtained when the ratio of “length of the straight body / diameter of the straight body” is 1.5 × (77 ÷ diameter of the straight body (mm)) or more. A more preferable effect is obtained when it is 0 × (77 ÷ straight body diameter (mm)) or more, and the most preferable effect is when the ratio is 2.5 × (77 ÷ straight body diameter (mm)) or more. Obtained.

Note that when silicon is added to gallium arsenide (GaAs), crystal defects called dislocations are reduced. As the silicon concentration in GaAs increases, the dislocations decrease and the dislocation density decreases. On the other hand, since the required silicon concentration and dislocation density differ depending on the type of device to be formed, the silicon concentration of the single crystal 40 to be manufactured is designed in consideration of these conditions. When the silicon concentration in the shoulder portion 41 is relatively low, 1 × 10 ¹⁷ cm ^{−3 to} 7 × 10 ¹⁷ cm ⁻³ , there is a problem that lineage is likely to occur in the conventional straight body portion. The present inventor has found for the first time that the occurrence of lineage in the straight body portion is suppressed by setting the dislocation density of the shoulder portion 41 to a certain value or less.

Here, in the silicon-added single crystal 40, the silicon concentration increases from the shoulder 41 toward the tail 43. Therefore, new dislocations are less likely to occur as the tail 43 is approached. That is, the dislocation density decreases from the shoulder 41 toward the tail 43. Therefore, the inventor has found that by controlling the dislocation density of the shoulder portion 41, the lineage occurrence rate in the straight body portion is drastically reduced. In the case where the silicon concentration in the shoulder 41 (average concentration of silicon) exceeds 7 × 10 ¹⁷ cm ⁻³ , lineage is hardly formed in the first place, and therefore the effect of the present invention is remarkably obtained. This is the case where the silicon concentration at 41 is 7 × 10 ¹⁷ cm ⁻³ or less. Further, in a single crystal to which silicon is not added, dislocations are likely to occur even in the straight body portion, and therefore it is considered difficult to suppress the generation of lineage only by controlling the dislocation density of the shoulder portion 41. Therefore, when the silicon concentration at the shoulder 41 is 1 × 10 ¹⁷ cm ⁻³ or more and 7 × 10 ¹⁷ cm ⁻³ or less as described above, the effect of the present invention is remarkable, and the silicon concentration is 1 × 10 10. The effect of the present invention becomes more conspicuous when it is ¹⁷ cm ⁻³ or more and 5.5 × 10 ¹⁷ cm ⁻³ or less, and the silicon concentration is 1 × 10 ¹⁷ cm ⁻³ or more and 4.0 × 10 ¹⁷ cm ^−3. The effects of the present invention are further remarkable when the following is set.

  Further, the concentration of silicon increases from the shoulder portion 41 toward the tail portion 43 in the length direction of the crystal (the extending direction of the single crystal 40) according to the formula of natural solidification. Therefore, when the ratio of the length of the single crystal to the diameter (ie, the ratio of “straight barrel length / straight barrel diameter”) is small, the concentration of silicon rapidly increases in the length direction, which causes dislocations. Will be suppressed. On the other hand, when the ratio between the length and diameter of the single crystal is large, the silicon concentration increases slowly in the length direction. Therefore, the present inventors have found that in the straight body portion, dislocations generated up to the shoulder portion 41 are accumulated to easily form lineage. Therefore, in such a single crystal 40 having a large ratio of the length and diameter of the single crystal (the ratio of the length of the straight body portion to the diameter is 1.5 or more), “inhibiting the formation of lineage” according to the present invention. This effect is particularly noticeable.

(Embodiment 4)
FIG. 12 is a schematic diagram showing a fourth embodiment of the single crystal manufacturing apparatus according to the present invention. The single crystal manufacturing apparatus according to the present invention will be described with reference to FIG.

  Referring to FIG. 12, single crystal manufacturing apparatus 1 includes pedestal 52, ampoule 3 mounted on pedestal 52, crucible 4 held in ampoule 3, and raw material filled in crucible 4. And a heater 5 for heating. The pedestal 52 is a cylindrical body having a circular planar shape, and has a mortar-shaped inclined portion 12 on the upper surface, and a concave portion 11 located on the inner peripheral side of the inclined portion 12 (approximately the center of the upper surface). Have The planar shape of the recess 11 is, for example, a circular shape, and the width of the recess 11 is substantially constant in the depth direction. The inclined portion 12 is configured to be inclined (relative to the bottom wall of the pedestal 52) such that the distance from the bottom wall of the pedestal 52 increases from the upper end of the recess 11 toward the outer peripheral side of the pedestal 52. As a material of the pedestal 52, for example, quartz can be used. Further, the material of the pedestal 52 is a material having a thermal expansion coefficient within a range of ± 50% of the thermal expansion coefficient of quartz constituting the ampoule 3 and sufficient at a heat treatment temperature for forming a single crystal. Any material can be used as long as the material has strength (for example, a melting point higher than the heat treatment temperature). For example, as the material of the pedestal 52, quartz, a mixture of quartz and alumina, or porous silica can be used.

  The ampule 3 mounted on the pedestal 52 is a quartz ampule (quartz ampule), and the shape thereof is substantially cylindrical. The bottom surface of the ampoule 3 has a shape that can be mounted on the upper surface of the pedestal 52 described above. More specifically, the ampoule 3 is housed in the concave portion 11 of the pedestal 52, and has a small-diameter portion 21 whose planar shape is substantially circular, and continues on the small-diameter portion 21, along the inclined portion 12 of the pedestal 52. The diameter-enlarged portion 22 having the inclined side wall and the enlarged-diameter portion 22 are connected to the enlarged-diameter portion 22. The planar shape is, for example, a circular shape similar to the pedestal 52, and the change rate of the width (diameter) is smaller than that of the enlarged-diameter portion 22. And a straight body portion 23. The width of the small diameter portion 21 is substantially constant at an arbitrary position in the depth direction. The small diameter portion 21 has a shape along the inner wall of the recess 11 of the pedestal 52. The inclination angle of the side wall (relative to the side wall of the straight body portion 23) in the enlarged diameter portion 22 of the ampoule 3 is substantially the same as the inclination angle of the inclined portion 12 of the base 52 (relative to the outer peripheral side wall of the base 52).

  The crucible 4 held inside the ampoule 3 basically has a shape along the inner peripheral surface of the ampoule 3. Specifically, a small-diameter portion 31 of the crucible 4 housed inside the small-diameter portion 21 of the ampoule 3 is formed at the center of the bottom of the crucible 4. The planar shape of the small diameter portion 31 is, for example, a circular shape. An enlarged diameter portion 32 of the crucible 4 is formed from the upper end portion of the small diameter portion 31 along the enlarged diameter portion 22 of the ampoule 3. The straight body portion 33 is formed so as to continue to the upper end of the enlarged diameter portion 32. The straight barrel portion 33 of the crucible 4 is basically disposed along the inner peripheral surface of the straight barrel portion 23 of the ampoule 3. And the heater 5 is arrange | positioned so that the outer periphery of the base 52, the ampoule 3, and the crucible 4 may be enclosed.

  Next, a single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. 12 will be described. FIG. 13 is a flowchart showing a single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. As shown in FIG. 13, in the method for producing a single crystal according to the present invention, first, a single crystal preparation step (S10) is performed. Specifically, a single-crystal piece serving as a seed crystal is inserted into the small-diameter portion 31 of the crucible 4 shown in FIG.

  Next, as shown in FIG. 13, a raw material preparation step (S20) is performed. Specifically, a predetermined amount of polycrystalline raw material pieces to be single crystal raw materials are put into the crucible 4. As the composition of the single crystal piece and the polycrystalline raw material piece, any crystalline material can be used. For example, gallium arsenide (GaAs) containing silicon can be used as the composition. In the case of a material having a high dissociation pressure such as gallium arsenide, the quartz ampule may be sealed in a vacuum.

  Next, a heating step (S30) is performed as shown in FIG. Specifically, by energizing the heater 5 shown in FIG. 12, the polycrystalline raw material pieces inside the crucible 4 are heated to a molten state. At this time, the heating condition by the heater 5 is adjusted so that the single crystal piece disposed in the small diameter portion 31 of the crucible 4 does not melt.

  Next, as shown in FIG. 13, a crystal growth step (S40) is performed. Specifically, the temperature of the melted polycrystalline raw material is adjusted by moving the pedestal 52, the ampoule 3 and the crucible 4 to the lower side of FIG. 4 gradually decreases from the vicinity of a single crystal piece (seed crystal) disposed in the small-diameter portion 31. As a result, the heated and melted raw material gradually solidifies (crystallizes) from the vicinity of the seed crystal. The solidified part is a single crystal. Then, by gradually pulling out the pedestal 52, the ampule 3 and the crucible 4 from the inner peripheral side of the heater 5 to the lower side, the melted raw material is gradually added from the lower side of the crucible 4 (that is, near the seed crystal). It will crystallize. In this way, a single crystal can be grown. When the melted raw material is completely solidified, “a cooling step (S50) is performed. In the cooling step (S50), the temperature of the heater 5 is decreased, and the single crystal inside the crucible 4 is cooled to room temperature.

  At this time, by using, for example, transparent quartz as the material of the pedestal 52, the difference in thermal expansion coefficient between the ampoule 3 made of quartz and the pedestal 52 can be reduced to a substantially negligible level. Therefore, when the temperature of the pedestal 52 and the ampoule 3 changes in order to grow the single crystal described above, the value of the thermal stress applied to the ampoule 3 due to the difference in the thermal expansion coefficient between the pedestal 52 and the ampoule 3. Can be reduced. Therefore, it is possible to prevent the problem that the ampule 3 is damaged due to the temperature change between the base 52 and the ampule 3.

  Further, by using a transparent member such as transparent quartz as the material of the pedestal 52, radiant heat is transmitted from the crucible 4 to the outer peripheral side of the pedestal 52 via the inclined portion 12 of the pedestal 52. For this reason, as shown in FIG. 14, when the solid-liquid interface 17 between the grown single crystal 15 and the molten material 16 reaches the straight body portion 33 of the crucible 4, the solid-liquid interface 17 protrudes toward the molten material 16 side. It can be set as the shape which becomes. As a result, in the formed single crystal 15, it is possible to suppress the occurrence of crystal defects (lineage) in the vicinity of the lower portion of the straight body portion 33. FIG. 14 is a schematic diagram for explaining a use state of the single crystal manufacturing apparatus shown in FIG.

  Here, the transparent member means a material having a transmittance of 90% or more per unit length (1 cm) for light having a wavelength of 2000 nm. The transmittance means the ratio ((intensity of transmitted light) / (intensity of incident light) × 100) between the intensity of the light incident on the transparent member and the intensity of light transmitted through the transparent member. . Therefore, as the transparent member, for example, quartz glass such as GE124 manufactured by Momentive Performance Materials can be used.

  FIG. 15 is an enlarged schematic view showing a first modification of the single crystal manufacturing apparatus shown in FIG. With reference to FIG. 15, the 1st modification of the single-crystal manufacturing apparatus 1 shown in FIG. 12 is demonstrated.

  Referring to FIG. 15, the first modification of the single crystal manufacturing apparatus according to the present invention basically has the same configuration as that of single crystal manufacturing apparatus 1 shown in FIG. 12 is different from the single crystal manufacturing apparatus 1 shown in FIG. 12 in that an uneven shape portion 13 as an anti-adhesion layer is formed on the surface. By doing so, it is possible to suppress the occurrence of trouble such that the ampoule 3 and the pedestal 52 adhere to the inclined portion 12 when forming a single crystal. In addition, the surface roughness in the uneven | corrugated shaped part 13 of the inclination part 12 can be 0.5 or more and 9.5 or less in Ra (refer JISB0601-1994). The surface roughness is more preferably 1.5 or more and 7.0 or less in Ra, and further preferably 2.5 or more and 4.5 or less in Ra. If the unevenness of the inclined portion is too small, the contact area increases and the ampoule 3 or the crucible and the pedestal 52 are likely to stick. On the other hand, if Ra is too large, the number of convex portions that come into contact with the ampoule 3 or the crucible is reduced, and the contact pressure to the individual convex portions is increased so that sticking is likely to occur. That is, the surface roughness is preferably 0.5 to 9.5, more preferably 1.5 to 7.0, and still more preferably 2.5 to 4.5 in terms of Ra.

  FIG. 16 is an enlarged schematic view showing a second modification of the single crystal manufacturing apparatus shown in FIG. With reference to FIG. 16, the 2nd modification of the single-crystal manufacturing apparatus 1 shown in FIG. 12 is demonstrated.

  Referring to FIG. 16, the second modification of the single crystal manufacturing apparatus basically has the same configuration as that of single crystal manufacturing apparatus 1 shown in FIG. 12, but prevents sticking to inclined portion 12 of pedestal 52. The processing layer 19 is different from the single crystal manufacturing apparatus 1 shown in FIG. This anti-adhesion treatment layer 19 is a layer made of a material having a relatively low reactivity with quartz that is a material constituting the ampoule 3 (as compared to a case where quartz is in contact with each other). A film or the like can be used. The film thickness of the anti-sticking treatment layer 19 is 10 μm or more and 1 mm or less, more preferably 50 μm or more and 500 μm or less, and further preferably 100 μm or more and 300 μm or less. By adopting such a configuration, the same effect as that of the single crystal manufacturing apparatus shown in FIG. 15 can be obtained.

  FIG. 17 is a partially enlarged schematic view showing a third modification of the single crystal manufacturing apparatus shown in FIG. With reference to FIG. 17, the 3rd modification of the single-crystal manufacturing apparatus shown in FIG. 12 is demonstrated.

  Referring to FIG. 17, the single crystal manufacturing apparatus basically has the same configuration as single crystal manufacturing apparatus 1 shown in FIG. 12, but between surface 14 of inclined portion 12 of pedestal 52 and ampoule 3. The point in which the mold release agent 20 is arrange | positioned differs from the single crystal manufacturing apparatus 1 shown in FIG. Even with this configuration, it is possible to prevent sticking between the pedestal 52 and the ampoule 3 as in the single crystal manufacturing apparatus shown in FIG. As the release agent 20, for example, SiC powder, alumina powder, or the like can be used. The particle size of the release agent 20 is preferably 0.1 μm or more and 20 μm or less, more preferably 0.3 μm or more and 15 μm or less, and further preferably 0.5 μm or more and 10 μm or less.

(Embodiment 5)
FIG. 18 is a schematic diagram showing a fifth embodiment of the single crystal manufacturing apparatus according to the present invention. A fifth embodiment of the single crystal manufacturing apparatus according to the present invention will be described with reference to FIG.

  Referring to FIG. 18, single crystal manufacturing apparatus 1 basically has the same structure as single crystal manufacturing apparatus 1 shown in FIG. 12, but the configuration of pedestal 52 is the same as that of single crystal manufacturing apparatus 1 of FIG. Is different. Specifically, in the single crystal manufacturing apparatus 1 shown in FIG. 18, the pedestal 52 is composed of a base body 25 and a quartz member 26 stacked on the base body 25. The quartz member 26 includes the inclined portion 12 that comes into direct contact with the enlarged diameter portion of the ampoule 3. For the base body 25, a different material other than quartz can be used. On the other hand, the quartz member 26 is made of transparent quartz. The shape of the base 52 made of the base body 25 and the quartz member 26 shown in FIG. 18 is basically the same as that of the base 52 in the single crystal manufacturing apparatus 1 shown in FIG.

  Even with this configuration, it is possible to obtain the same effect as the single crystal manufacturing apparatus 1 shown in FIG. Furthermore, since the pedestal 52 is composed of the base body 25 and the quartz member 26, for example, the material of the base body 25 can be arbitrarily changed in order to adjust the characteristics such as the heat conduction characteristics and strength of the pedestal 52. .

  The above-described single crystal manufacturing apparatus 1 according to the present invention is suitably used for manufacturing a semiconductor single crystal, and particularly suitable for manufacturing a gallium arsenide single crystal and an indium phosphide single crystal.

  Although there is a part which overlaps with description of embodiment mentioned above, the characteristic structure of this invention is enumerated below.

  The single crystal manufacturing apparatus 1 according to the present invention heats and dissolves a raw material (polycrystalline raw material piece) held in a raw material holding container (the ampoule 3 and the crucible 4 in FIG. 1 or the crucible 4 in FIG. 7). A single crystal production apparatus 1 for producing a single crystal by solidifying from one direction, comprising a raw material holding container (ampoule 3 and crucible 4 in FIG. 1 or crucible 4 in FIG. 7), a pedestal 2 and a heater 5 Prepare. The pedestal 2 supports the ampoule 3 in FIG. 1 or the crucible 4 in FIG. The heater 5 is for heating the ampoule 3 and the crucible 4 of FIG. 1 or the crucible 4 of FIG. The material constituting the pedestal 2 has a thermal conductivity of 0.5 W / (m · K) or more and below the value of the thermal conductivity of the single crystal to be formed. The material constituting the pedestal 2 has a light transmittance of 10% or less for a wavelength of 1600 nm to 2400 nm with respect to the material having a thickness of 4 mm. Moreover, it is more preferable that the transmittance of the material constituting the pedestal 2 is 5% or less. Further, the thermal conductivity of the material constituting the pedestal 2 is ½ or less of the thermal conductivity of the single crystal to be formed, more preferably ¼ or less of the thermal conductivity of the single crystal to be formed. .

  In this way, the material constituting the pedestal 2 is made of a polycrystalline material in the crucible 4 by adopting a relatively simple structure in which the wavelength is 1600 nm or more and 2400 nm or less. When the piece is in a molten state and solidified from one direction (specifically, from the pedestal 2 side), the flow of heat transferred from the molten raw material to the pedestal 2 is guided in the direction toward the lower surface of the pedestal 2 (downward). be able to. As a result, a solid-liquid interface 17 that is a boundary between the molten material 16 (liquid phase) in FIG. 3 and the single crystal 15 (solid phase) in FIG. It becomes possible to make it flat or convex toward the molten material 16 side. For this reason, when the solid-liquid interface 17 is located in the enlarged diameter part 32 of the crucible 4, the said solid-liquid interface 17 can be made flat or convex shape to the molten material 16 side as mentioned above. As a result, generation of crystal defects can be suppressed in the obtained single crystal 15.

  In the single crystal manufacturing apparatus 1, the anti-adhesion layer (uneven shape portion 13, anti-adhesion treatment layer) is formed on the surface of the pedestal 2 where the ampule 3 shown in FIGS. 4 to 6 or the crucible 4 shown in FIGS. 19, mold release agent 20) may be formed. Here, when the raw material accommodated in the crucible 4 is heated by the heater 5 to produce a single crystal, the ampule 3 holding the crucible 4 shown in FIGS. 4 to 6 or the crucible 4 shown in FIGS. Becomes heated. Then, the heated ampule 3 or the crucible 4 is supported by the pedestal 2 (in contact with the pedestal 2) (the diameter-enlarged portion 22 of the ampule 3 in FIGS. 4 to 6 and the inclined portion 12 of the pedestal 2). In the crucible 4 of FIG. 8 to FIG. 10 or the crucible 4 of FIG. 8 to FIG. 10 where the inclined portion 12 of the pedestal 2 is in contact with the ampule 3 and crucible 4 (see FIG. 4 to FIG. 6) or crucible 4. The ampoule 3 or the crucible 4 is pressed against the base by its own weight (see FIGS. 8 to 10). As a result, the ampoule 3 or the crucible 4 may adhere to the base 2 in some cases. When ampule 3 or crucible 4 is fixed to pedestal 2 in this way, when heat treatment is performed to form a single crystal (that is, heating step (S30) and crystal growth step (S40) in FIG. 2) and cooling to room temperature. In the process (when the cooling step (S50) is performed), stress is generated in the fixed portion due to the difference in thermal expansion between the ampoule 3 or the crucible 4 and the base 2. Such stress causes damage to the ampoule 3, the crucible 4 or the base 2.

  Therefore, if the anti-adhesion layer (uneven portion 13, anti-adhesion treatment layer 19, release agent 20) is formed as described above to prevent the ampule 3 or the crucible 4 from adhering to the base 2, the ampule 3 Since the crucible 4 and the pedestal 2 can be individually expanded and contracted, it is possible to suppress the occurrence of stress due to the above-mentioned fixation. As a result, the possibility of damage to the ampoule 3, the crucible 4 or the base 2 can be further reduced.

  In the single crystal manufacturing apparatus 1, as shown in FIGS. 1 and 3 to 6, the raw material holding container includes a crucible 4 as a raw material container for holding the raw material, and a quartz ampule that holds the crucible 4 inside. Ampoule 3 may be included. The thermal expansion coefficient of the material constituting at least the portion that contacts the ampoule 3 in the pedestal 2 may be a value included within a range of ± 50% of the thermal expansion coefficient of quartz constituting the ampoule 3.

  In this way, when the crucible 4 is heated by the heater 5 in order to produce a single crystal, and the temperature of the crucible 4 is obtained in order to obtain a single crystal by solidifying the raw material that has become a liquid phase by heating. When lowering, the difference in thermal expansion between the ampoule 3 and the base 2 can be made sufficiently small. As a result, it is possible to suppress the occurrence of a problem that the ampoule 3 or the pedestal 2 is damaged due to the difference in the thermal expansion amount.

  In the single crystal manufacturing apparatus 1, the raw material holding container may include the ampule 3 as a quartz ampule supported by the pedestal 2, and the material constituting at least the portion in contact with the ampule 3 in the pedestal 2 is quartz. May be. Preferably, the material constituting the base 2 may be quartz. In this case, the base 2 is made of the same material as the ampoule 3. For this reason, since the thermal expansion coefficient of the ampoule 3 and the base 2 becomes the same, generation | occurrence | production of the problem of the damage resulting from the difference of the above thermal expansion amounts can be suppressed more reliably.

  In the single crystal manufacturing apparatus 1, the anti-adhesion layer may be a concavo-convex shape portion 13 as shown in FIG. This uneven | corrugated shaped part 13 may be formed by roughening the said surface (inclined part 12) in the base 2, for example. In this case, the area directly contacting the ampoule 3 or the crucible 4 on the surface of the base 2 can be reduced. As a result, the possibility that the ampoule 3 or the crucible 4 is fixed to the base 2 can be reduced.

  Further, as shown in FIG. 5 or FIG. 9, the anti-adhesion layer has a reactivity with quartz constituting the quartz ampule or a reactivity with the material constituting the crucible 4 from the material constituting the main body portion of the base 2. The anti-sticking treatment layer 19 made of a low material may be used. The anti-sticking treatment layer 19 may be a single layer or may have a laminated structure in which a plurality of layers are laminated. Further, as the anti-adhesion treatment layer 19, a modification layer obtained by performing modification treatment (for example, crystallization treatment on the pedestal surface) on the surface of the pedestal 2 may be used. Also in this case, the possibility that the ampoule 3 or the crucible 4 is fixed to the base 2 can be reduced.

  The method for producing a single crystal according to the present invention is a method for producing a single crystal using the single crystal production apparatus 1, and the following steps are performed. That is, a step (seed crystal preparation step (S10) in FIG. 2) and a step of inserting a seed crystal and a single crystal raw material (polycrystalline raw material piece) into a raw material holding container (crucible 4 in FIGS. 1 and 3 to 10) and A raw material preparation step (S20)) is performed. And the process (heating process (S30) which heats a raw material substance by heating the raw material holding | maintenance container (The ampule 3 and the crucible 4 of FIG. 1, FIG. 3-6, or the crucible 4 of FIG. 7-10)) with the heater 5. FIG. )). Further, a step of manufacturing a single crystal (crystal growth step (S40)) is carried out by gradually solidifying the molten source material (polycrystalline source piece) from the seed crystal side.

  In this way, when the polycrystalline raw material piece is once melted (heating step (S30)) and then subjected to a solidification process (crystal growth step (S40)), the molten raw material is transmitted to the base 2. The heat flow can be guided in a direction (downward) toward the lower surface of the base 2. As a result, as shown in FIG. 3, the boundary portion (solid-liquid interface 17) between the molten material 16 (liquid phase) and the single crystal 15 (solid phase), which is a portion where the raw material has solidified into a single crystal, It becomes possible to make it flat or convex toward the molten material 16 side. For this reason, when the solid-liquid interface 17 is located in the enlarged diameter part 32 of the crucible 4, the said solid-liquid interface 17 can be made flat or convex shape to the molten material 16 side as mentioned above. As a result, generation of crystal defects can be suppressed in the obtained single crystal 15.

In the method for producing a single crystal, the produced single crystal may be made of gallium arsenide (GaAs) containing silicon (Si). The single crystal has a single crystal widened portion that gradually increases in width from the seed crystal side, and a rate of change in width that is continuous with the single crystal widened portion is smaller than that of the single crystal widened portion (for example, the width is substantially smaller). And a straight body portion). The boundary between the single crystal enlarged diameter portion and the straight body portion (the enlarged diameter portion where the diameter is enlarged in the single crystal 15 shown in FIG. 3, and the diameter continuous to the enlarged diameter portion is substantially constant. The average concentration of silicon in a plane perpendicular to the growth axis direction of the single crystal at the boundary with the straight body portion may be 1 × 10 ¹⁷ cm ⁻³ or more and 7 × 10 ¹⁷ cm ⁻³ or less. Further, the average value of the dislocation density at the boundary may be 0 cm ⁻² or more and 2000 cm ⁻² or less. As described above, particularly when the single crystal is formed with respect to the Si-containing GaAs described above, the effect of suppressing the generation of defects is particularly remarkable when the manufacturing method according to the present invention is applied.

Further, from a different point of view, the single crystal 40 according to the present invention is a single crystal 40 made of gallium arsenide containing silicon and has a single crystal diameter-expanded portion that gradually increases in width from the seed crystal side (see FIG. 11 below the shoulder portion 41) and a straight body portion (a body having a substantially constant diameter in FIG. 11) that is connected to the single crystal widened portion and whose width change rate is smaller than that of the single crystal widened portion. Part). The average concentration of silicon in the plane perpendicular to the growth axis direction of the single crystal 40 is 1 × 10 ¹⁷ cm ⁻³ or more and 7 × 10 ^{17 at} the boundary (shoulder portion 41) between the single crystal expanded portion and the straight body portion. cm ⁻³ or less, and the average value of dislocation density is from 0 cm ^{−2 to} 2000 cm ⁻² .

  Thus, by controlling the dislocation density in the shoulder 41 within the above range, the generation of lineage in the trunk can be effectively suppressed. Moreover, when the average concentration of silicon is as described above, pits (minute pits) due to dislocations may occur in the polishing process of the wafer cut out from the single crystal. In the wafer cut out from the single crystal whose dislocation density at 41 is controlled, the generation of such pits is suppressed.

  In the single crystal 40, the ratio of the length of the straight body portion to the diameter (length of the straight body portion / diameter) is preferably 1.5 or more. Thus, the effect of the present invention is particularly remarkable in a single crystal having a large ratio between the length and diameter of the straight body portion.

  In addition, the larger the diameter of the single crystal 40 obtained, the more difficult it is to suppress the depression of the solid-liquid interface at the enlarged diameter portion, so the dislocation density tends to increase at the shoulder portion 41. In addition, since the solid-liquid interface is easily concaved in the body part (straight body part) and a large temperature difference is likely to occur inside the crystal, the formation of lineage becomes more remarkable. The single crystal of the present invention and the method for producing the same show a remarkable effect when the shoulder diameter is 77 mm or more, a more remarkable effect when the diameter is 102 mm or more, and even more remarkable when the diameter is 152 mm or more. An effect is obtained.

  A single crystal manufacturing apparatus 1 according to the present invention is a single crystal manufacturing apparatus that heats and melts a raw material (polycrystalline raw material piece) held in a raw material container (crucible 4) and then solidifies it from one direction. The crystal manufacturing apparatus 1, which is a crucible 4 as a raw material container, a quartz ampule (ampule 3) that holds the crucible 4 inside, a pedestal 52 that supports the ampule 3, and a heater 5 for heating the crucible 4. Is provided. The thermal expansion coefficient of the material constituting at least the part in contact with the ampoule 3 in the pedestal 52 is a value included in a range within ± 50% of the thermal expansion coefficient of quartz constituting the ampoule 3.

  In this way, when the crucible 4 is heated by the heater 5 in order to produce a single crystal, and the temperature of the crucible 4 is obtained in order to obtain a single crystal by solidifying the raw material that has become a liquid phase by heating. When lowering, the difference in thermal expansion between the ampoule 3 and the pedestal 52 can be made sufficiently small. As a result, it is possible to suppress the occurrence of a problem that the ampoule 3 or the pedestal 52 is damaged due to the difference in the amount of thermal expansion.

  In the single crystal manufacturing apparatus 1, as shown in FIGS. 15 to 17, in the pedestal 52, the surface of the portion in contact with the ampoule 3 has an anti-adhesion layer (uneven shape portion 13, anti-adhesion treatment layer 19, release agent). 20) may be formed. Here, when the crucible 4 is heated by the heater 5 in order to produce a single crystal, the ampoule 3 is also heated. In the region where the heated ampule 3 is supported by the pedestal 52 (in contact with the pedestal 52) (the portion where the enlarged diameter portion 22 of the ampule 3 and the inclined portion 12 of the pedestal 52 are in contact), the ampule 3 The ampule 3 is pressed against the pedestal by its own weight. As a result, the ampoule 3 may adhere to the pedestal 52. When ampule 3 is fixed to pedestal 52 in this way, heat treatment is performed to form a single crystal (that is, heating step (S30), crystal growth step (S40) and cooling step (S50) in FIG. 13) are performed. In this case, stress is generated in the fixed portion due to the difference in thermal expansion between the ampoule 3 and the pedestal 52. Such stress causes damage to the ampoule 3 or the pedestal 52.

  Therefore, if the anti-adhesion layer (uneven shape portion 13, anti-adhesion treatment layer 19, release agent 20) is formed as described above to prevent the ampule 3 from adhering to the base 52, the ampule 3 and the base 52 are provided. Can be individually expanded and contracted, so that it is possible to suppress the occurrence of stress due to the above-mentioned fixation. As a result, the possibility of damage to the ampoule 3 or the pedestal 52 can be further reduced.

  In the single crystal manufacturing apparatus 1, the material constituting the pedestal 52 may be quartz. In the single crystal manufacturing apparatus 1, the material constituting at least the portion in contact with the quartz ampule in the pedestal may be quartz. In this case, the pedestal 52 is made of the same material as the ampule 3. For this reason, since the thermal expansion coefficients of the ampoule 3 and the pedestal 52 are the same, it is possible to more reliably suppress the occurrence of problems such as damage due to the difference in the amount of thermal expansion as described above.

  In the single crystal manufacturing apparatus 1, the anti-adhesion layer may be an uneven portion 13 as shown in FIG. This uneven | corrugated shaped part 13 may be formed by roughening the said surface (inclined part 12) in the base 52, for example. In this case, the area directly contacting the ampoule 3 on the surface of the pedestal 52 can be reduced. As a result, the possibility that the ampule 3 is fixed to the pedestal 52 can be reduced.

  Further, the anti-adhesion layer may be an anti-adhesion treatment layer 19 made of a material having low reactivity with quartz constituting the quartz ampule as shown in FIG. The anti-sticking treatment layer 19 may be a single layer or may have a laminated structure in which a plurality of layers are laminated. Further, as the anti-adhesion treatment layer 19, a modification layer obtained by performing modification treatment (for example, crystallization treatment on the pedestal surface) on the surface of the pedestal 52 may be used. Also in this case, the possibility that the ampule 3 is fixed to the pedestal 52 can be reduced.

  In the single crystal manufacturing apparatus 1, the pedestal 52 may be made of a transparent member. In this case, heat radiation by radiation is promoted from the heated crucible 4 and the ampoule 3 downward (in the direction from the crucible 4 toward the pedestal 52) through the transparent pedestal 52, compared to the case where the pedestal 52 is an opaque member. . Therefore, in the vicinity of the lower portion of the straight body portion 33, as shown in FIG. 14, the solid-liquid interface 17 that is an interface between the molten material 16 (liquid phase) and the solidified single crystal 15 (solid phase) It can be convex on the side. Thus, by making the solid-liquid interface 17 convex to the liquid phase side, it is possible to suppress the occurrence of defects in the single crystal 15 that occurs when the solid-liquid interface 17 is convex to the solid phase side.

  The method for producing a single crystal according to the present invention is a method for producing a single crystal using the single crystal production apparatus 1 and includes the following steps. That is, first, a step of inserting a seed crystal (single crystal 15) and a single crystal raw material (polycrystalline raw material piece) into a raw material container (crucible 4) (seed crystal preparation step (S10) in FIG. 13) and a raw material preparation step ( S20)) is carried out. And the process (heating process (S30)) of melting a polycrystalline raw material piece by heating a raw material container (crucible 4) with the heater 5 is implemented. Further, a step of manufacturing a single crystal (crystal growth step (S40)) is carried out by gradually solidifying the molten source material (polycrystalline source piece) from the seed crystal side.

  In this way, the polycrystalline raw material pieces are once melted (heating step (S30)) and then solidified (crystal growth step (S40) and further cooled to room temperature (cooling step (S50)). )), There is no significant difference in the coefficient of thermal expansion between the ampule 3 made of quartz and the pedestal 52. Therefore, the occurrence of problems such as damage to the ampule 3 and the pedestal 52 can be suppressed. Since the deterioration of the quality of the single crystal resulting from the breakage of 52 can be suppressed, a high-quality single crystal can be obtained stably.

In the method for producing a single crystal, the single crystal may be made of gallium arsenide not containing silicon (Si) as an additive or gallium arsenide (GaAs) containing silicon (Si). The single crystal has a single crystal enlarged portion that gradually increases in width from the seed crystal side, and a straight body portion that is connected to the single crystal enlarged portion and has a width change rate smaller than that of the single crystal enlarged portion. May be included. Boundary between the single crystal enlarged diameter portion and the straight body portion (the enlarged diameter portion having an enlarged diameter in the single crystal 15 shown in FIG. 14 and the straight body portion having a constant diameter connected to the enlarged diameter portion. The concentration of silicon (Si) at the boundary) is 7 × 10 ¹⁷ cm ⁻³ or less, more preferably 5.5 × 10 ¹⁷ cm ⁻³ or less, and even more preferably 4.0 × 10 ¹⁷ cm ⁻³ or less. May be. As described above, particularly when the single crystal is formed with respect to the Si-containing GaAs described above, the effect of suppressing the generation of defects is particularly remarkable when the manufacturing method according to the present invention is applied. Here, gallium arsenide that does not contain silicon as an additive means that silicon is not intentionally added, and even when silicon is contained as an inevitable impurity, it is actively added. The thing to which silicon is not added is included.

Example 1
In order to confirm the effect of the present invention, experiments for manufacturing GaAs single crystals under various conditions were conducted as follows.

(Experimental conditions)
(A) 3 inch diameter gallium arsenide crystal growth Using the apparatus of the present invention, a 3 inch diameter gallium arsenide crystal containing silicon was grown. A crucible made of pyrolytic boron nitride (pBN) having a seed crystal accommodating portion at the tip was used. This crucible contains seed crystals, pre-synthesized gallium arsenide (GaAs) raw material, boron oxide (B ₂ O ₃ ) as a sealant, and silicon (Si) as a dopant, and a quartz ampoule is vacuum sealed. went. The quartz ampule was placed on a base made of opaque quartz. A test piece having a thickness of 2 mm made of the same material as the opaque quartz used for the pedestal was prepared, and the thermal conductivity was measured at room temperature by the laser flash method. As a result, a value of 1.4 W / (m · K) was obtained. (For the results under the experimental conditions described here, see Experiment 4 in Table 1 described later). Further, as a result of preparing a test piece having a thickness of 4 mm and measuring the light transmittance using a spectrophotometer, the light transmittance is 10% or less in a wavelength region of 1600 to 2400 nm, and a gallium arsenide crystal ( It was confirmed that light in the wavelength region that is dominant at the growth temperature (melting point: 1238 ° C.) hardly transmits. Further, in order to prevent the quartz ampoule from being fixed, the pedestal inclined portion is adjusted to Ra = 3.5 by grinding and further subjected to heat treatment at 1200 ° C. for 72 hours in the atmosphere to crystallize the surface. Went.

  Then, a heater arranged so as to surround the outer periphery of the pedestal, quartz ampule, and crucible is energized and heated to bring the gallium arsenide raw material and boron oxide into a molten state. Then, the crucible was lowered and pulled out to the low temperature side of the heater, and the molten raw material was solidified in one direction from the seed crystal toward the tail portion to grow a gallium arsenide single crystal containing silicon. After completion of crystal growth, the sample was cooled to room temperature, the quartz ampule was removed from the pedestal, and the crystal was taken out by cutting and opening. The diameter of the crystal was 77 mm at the shoulder.

  About the obtained single crystal, the silicon concentration in a shoulder part was measured. The silicon concentration was calculated by performing SIMS analysis on three 10 mm square chips from the middle of the wafer, near the edge of the wafer, and the middle of the wafer cut vertically in the length direction at the crystal shoulder, and the average value of the three points. Asked.

  Further, the dislocation density at the shoulder of the single crystal was measured. The dislocation density is the average value of the dislocation density by etching the wafer obtained from the shoulder of the single crystal with KOH (potassium hydroxide) and then measuring the number of etch pits in the radial direction at a pitch of 5 mm using a Nomarski microscope. Asked.

  For the single crystal, the number of scatterers at the shoulder was measured. Specifically, the wafer was collected from the shoulder and polished, and the number of scatterers on the entire surface of the wafer was measured using a surface foreign matter inspection apparatus (Surfscan 6220 manufactured by KLA-Tencor).

  Further, a gallium arsenide single crystal having a shoulder diameter of 85 mm was also formed by the same process as the above-described single crystal having a diameter of 3 inches, and the same measurement was performed.

(B) 4 inch diameter gallium arsenide crystal growth A 4 inch diameter gallium arsenide single crystal is formed by basically the same method as the above described 3 inch diameter gallium arsenide crystal growth, and the same method is used for similar items. The measurement was performed using However, the pedestal slope was sandblasted after grinding and adjusted to Ra = 7.0. Moreover, about the base inclination part, after the surface crystallization process, the alumina powder with a particle size of 10 micrometers was apply | coated finally. Then, after the crystal growth was completed, it was cooled to room temperature, the quartz ampule was removed from the pedestal, and cut and released to take out the crystal. The diameter of the crystal was 102 mm at the shoulder.

  In addition, a gallium arsenide single crystal having a shoulder diameter of 110 mm was formed by the same process as the above-described single crystal having a 4-inch diameter, and the same measurement was performed.

(C) 6-inch diameter gallium arsenide crystal growth A 6-inch diameter gallium arsenide single crystal is formed by basically the same method as the above-described 3-inch diameter gallium arsenide crystal growth, and the same method is used for similar items. The measurement was performed using However, the pedestal slope was adjusted to Ra = 9.5 by sandblasting after grinding. Moreover, about the base inclination part, after the surface crystallization process, the SiC powder with a particle size of 20 micrometers was apply | coated finally. Then, after the crystal growth was completed, it was cooled to room temperature, the quartz ampule was removed from the pedestal, and cut and released to take out the crystal. The diameter of the crystal was 152 mm at the shoulder.

  In addition, a gallium arsenide single crystal having a shoulder diameter of 160 mm was formed by the same process as that of the 6-inch diameter single crystal described above, and the same measurement was performed.

(result)
(A) 3 inch diameter gallium arsenide crystal Tables 1 and 2 show the results of the experiment.

  Tables 1 and 2 show the “thermal conductivity” and “light transmittance” of the pedestal, “the silicon concentration of the shoulder” and “the dislocation density”, “the presence / absence of lineage” of the body, “the crystal body” The relationship between “length to diameter ratio” is shown. The length of the crystal body in Tables 1 and 2 is the length from the shoulder 41 to the tail 43 of the single crystal 40 shown in FIG. As can be seen from Tables 1 and 2, the single crystals obtained in Experiments 2 to 8, 12, and 13 according to the present invention have no lineage, and the number of scatterers at the shoulder is extremely small. It was. Further, the effect of the present invention could be confirmed in the same manner for a single crystal having a shoulder diameter of 85 mm.

(B) 4 inch diameter gallium arsenide crystal Tables 2 and 3 show the experimental results.

As can be seen from Tables 2 and 3, the single crystals obtained in Experiments 16 to 19 according to the present invention had no lineage and the number of scatterers at the shoulders was extremely small. In addition, the effect of the present invention was confirmed in the same manner for a single crystal having a shoulder diameter of 110 mm. In addition, about the experiment by which the dislocation density was displayed as zero in the table | surface, the case where the average value of a dislocation density was less than 0.5 cm ^<-2 > is meant.

(C) 6-inch diameter gallium arsenide crystal Table 3 shows the experimental results.

  As can be seen from Table 3, lineage was not generated in the single crystals obtained in Experiments 23 to 26 according to the present invention, and the number of scatterers at the shoulder was extremely small. In addition, the effect of the present invention was confirmed in the same manner for a single crystal having a shoulder diameter of 160 mm.

(Example 2)
In order to confirm the effect of the present invention, a pedestal having different thermal expansion coefficients was prepared, a single crystal was manufactured using the pedestal, and its durability was confirmed. Table 4 shows the investigation results of the material and durability of the base used in the test.

  Table 4 shows the thermal expansion coefficient of the pedestal and the number of breakage of the quartz ampule or pedestal. For the pedestal, transparent quartz and a mixture of quartz and alumina were used as a material having a larger coefficient of thermal expansion than quartz. Adjustment of the thermal expansion coefficient of the mixture of quartz and alumina was performed by adjusting the content ratio of alumina. Further, porous silica was used as a material having a smaller thermal expansion coefficient than quartz. Adjustment of the thermal expansion coefficient of porous silica was performed by adjusting the porosity. As can be seen from Table 4, for the pedestals 2 to 4 having a thermal expansion coefficient within ± 50% of the thermal expansion coefficient of quartz, the base was not damaged.

  It should be noted that in the case where the unevenness is formed on the pedestal inclined portion and Ra is 0.5 or more and 9.5 or less, the anti-sticking treatment layer is formed, the release agent is disposed, etc. In the crystal production, the problem that the quartz ampule and the pedestal were damaged did not occur at all, and the reproducibility of the single crystal quality was extremely good.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention is particularly effective when a single crystal is manufactured using the vertical boat method.

  DESCRIPTION OF SYMBOLS 1 Single crystal manufacturing apparatus, 2,52 base, 3 ampule, 4 crucible, 5 heater, 7 arrow, 11 recessed part, 12 inclined part, 13 uneven | corrugated shaped part, 14 surface, 15 single crystal, 16 molten material, 17 solid-liquid interface , 19 Adhesion prevention treatment layer, 20 Release agent, 21, 31 Small diameter part, 22, 32 Large diameter part, 23, 33 Straight body part, 25 Base body, 26 Quartz member, 40 Single crystal, 41 Shoulder part, 42 Body Department center, 43 tails.

Claims (12)

A single crystal production apparatus (1) for producing a single crystal by heating and melting the raw material held in the raw material holding container (3, 4) and then solidifying from one direction,
Raw material holding containers (3, 4);
A base (2) for supporting the raw material holding container (3, 4);
A heater (5) for heating the raw material holding container (3, 4),
The thermal conductivity of the material constituting the pedestal (2) is 0.5 W / (m · K) or more and below the value of the thermal conductivity of the single crystal to be formed,
The material which comprises the said base (2) is a single crystal manufacturing apparatus (1) whose transmittance | permeability of the light with respect to the said material whose thickness is 4 mm is 1600 nm or more and 2400 nm or less is 10% or less.   2. The unit according to claim 1, wherein an anti-adhesion layer (13, 19, 20) is formed on a surface of a portion of the pedestal (2) that contacts the raw material holding container (3, 4). Crystal manufacturing equipment. The raw material holding container (3, 4) includes a quartz ampoule (3) supported by the pedestal (2),
The single crystal manufacturing apparatus (1) according to claim 1, wherein a material constituting at least a portion in contact with the quartz ampoule (3) in the pedestal (2) is quartz. A method for producing a single crystal using the single crystal production apparatus according to claim 1,
Inserting seed crystal and single crystal source materials into the source holding containers (3, 4) (S10, S20);
Melting the raw material by heating the raw material holding container (3, 4) with the heater (5) (S30);
And a step (S40) of producing a single crystal by gradually solidifying the melted raw material from the seed crystal side. A single crystal made of gallium arsenide containing silicon,
A single crystal widened portion that gradually increases in width from the seed crystal side, and a straight body portion that is connected to the single crystal widened portion and has a width change rate smaller than the single crystal widened portion,
The average concentration of the silicon in a plane perpendicular to the growth axis direction of the single crystal is 1 × 10 ¹⁷ cm ⁻³ or more and 7 × 10 ¹⁷ cm ^{− at} the boundary between the single crystal expanded portion and the straight body portion. ^A single crystal having a dislocation density of 0 cm ⁻² or more and 2000 cm ⁻² or less.   The single crystal according to claim 5, wherein the ratio of the length of the straight body portion to the diameter is 1.5 or more. A single crystal production apparatus (1) for producing a single crystal by heating and melting the raw material held in the raw material container (4) and then solidifying from one direction,
A raw material container (4);
A quartz ampule (3) holding the raw material container inside;
A pedestal (52) for supporting the quartz ampule;
A heater (5) for heating the raw material container (4),
In the pedestal (52), at least the thermal expansion coefficient of the material constituting the portion in contact with the quartz ampule (3) is included within a range of ± 50% of the thermal expansion coefficient of quartz constituting the quartz ampule (3). The single crystal manufacturing apparatus (1) has a value that can be obtained.   The single crystal manufacturing apparatus according to claim 7, wherein an anti-adhesion layer (13, 19, 20) is formed on a surface of a portion of the pedestal (52) that is in contact with the quartz ampule (3). (1).   The single crystal manufacturing apparatus (1) according to claim 7, wherein the base (52) is made of a transparent member.   The single crystal manufacturing apparatus (1) according to claim 7, wherein a material constituting at least a portion in contact with the quartz ampoule (3) in the pedestal (52) is quartz. A method for producing a single crystal using the single crystal production apparatus (1) according to claim 7,
Inserting seed crystal and single crystal source materials into the source container (4) (S10, S20);
Melting the raw material by heating the raw material container (4) with the heater (5) (S30);
And a step (S40) of producing a single crystal by gradually solidifying the melted raw material from the seed crystal side. The single crystal is composed of gallium arsenide not containing silicon as an additive or gallium arsenide containing silicon,
The single crystal has a single crystal diameter-expanded portion that gradually increases in width from the seed crystal side, and a straight body portion that is connected to the single crystal diameter-expanded portion and has a rate of change in width that is smaller than that of the single crystal diameter-expanded portion. Including
The method for producing a single crystal according to claim 11, wherein a concentration of the silicon at a boundary between the single crystal enlarged diameter portion and the straight body portion is 7 × 10 ¹⁷ cm ^-3 or less.

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