JP2017114757A - Heat reflection plate structure of growth furnace for large-sized egf method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EFG growth furnace capable of stabilizing a growth condition between individual ribbons at the time of simultaneous growths of many sheets of ten or more, and preventing the occurrence of a side slip failure, thereby to shorten a spreading time period and to stabilize all sapphire ribbon widths to be grown, into a die-pack width.SOLUTION: In an EFG growth furnace to be provided, heat reflection plates laminated and arranged on a die-pack side face, excepting middle plates partially, are laminated, thereby to vary the quantity of a radiation heat irradiated from a heater upon the center and two ends of the die pack thereby to arrange temperature gradients at a die pack tip, and all sapphire ribbon sides to be grown can be stabilized with a die pack width.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a heat reflector structure of a growth furnace for an EFG method in which a sapphire ribbon is grown using an EFG method (Edge-defined Film-fed Growth method).

  Currently, many semiconductors represented by LEDs are constructed by growing a crystal film such as GaN on a substrate made of a single crystal material, and a cylindrical single crystal is grown for the production of the single crystal material. Two types are widely used: the Cz method and the EFG method for growing plate-like single crystals. Of these two kinds of growth methods, the EFG method capable of growing a single crystal formed in a plate shape in advance is suitable for the substrate application in its workability, and is disclosed in Patent 4245856 (hereinafter referred to as Patent Document 1). Description) and Japanese Patent No. 5702931 (hereinafter described as Patent Document 2) and the like improve the quality of crystals to be grown and enable use in semiconductor applications. With respect to this patent document, in Patent Document 1, when pulling up a sapphire ribbon that is a plate-like sapphire single crystal, the step structure on the surface of the sapphire ribbon is tilted in the same direction by tilting the pulling angle of the seed crystal immersed in the alumina melt. Even when unevenness such as thickness occurs, crystal defects are reduced. Moreover, regarding the several sapphire ribbon pulled up simultaneously from a single seed crystal, the effect of improving crystal quality collectively is also provided.

Moreover, in patent document 2, the transition in a crystal | crystallization is suppressed by setting two temperature gradients in the growth direction of a sapphire ribbon. More specifically, immediately after forming a crystal from the melt, the crystal is placed under a high cooling rate, and the cooling rate is decreased as the manufacturing process proceeds, thereby producing a single crystal sapphire ribbon that does not exhibit polycrystallinity. Is possible. In Patent Document 2, not only the temperature difference between the positions but also the speed at which the ribbon travels between the positions is added to the components of the temperature gradient.

Japanese Patent No. 4245856 Japanese Patent No. 5702931

  While the technical features and effects described above are used, in recent years, the demand for sapphire single crystal substrates used in LEDs has increased, and the crystal quality of the growth method using the EFG method described in Patent Documents 1 and 2 has been increased. There is a problem that the number of cultivated sheets cannot be increased while maintaining the above. That is, in the current sapphire ribbon growth using the EFG method, it is required to extend the length of the die pack with the increase in the number of growth and cope with simultaneous growth of 10 or more sheets. On the other hand, as a result of improving the crystal quality as a single unit, the growth method using the conventional method cannot give the effect of stable growth conditions between the ribbons, Therefore, a linear crystal defect (hereinafter referred to as a side slip defect) occurs at the end in the width direction at a rate of about half. In addition, in the simultaneous growth of a large number of sheets using the above-mentioned conventional technology, a part of the growing time due to the spreading time for expanding the crystal width from the seed crystal to both ends of the die pack or the difference in the growth conditions between the ribbons. There is also a problem such as a reduction in sapphire ribbon width.

  In the invention described in the present application with respect to the above-described problems, the growth conditions between the ribbons are stabilized when simultaneously growing a large number of sheets of 10 sheets or more, the occurrence of side slip defects is prevented, the spreading time is shortened, and the growth is performed. An object of the present invention is to provide an EFG growing furnace capable of stabilizing the width of all sapphire ribbons with the die pack width.

  For the above purpose, the present invention is characterized in that, in the EFG growth furnace, a part of the middle plate is removed from the heat reflecting plates laminated on the side surface of the die pack and laminated. More specifically, with respect to a plurality of heat reflecting plates provided around the tip of the die pack protruding from the lid covering the crucible end surface, the heat reflection laminated on the side surface of the die pack corresponding to the width direction of the grown crystal. A technical feature is that a part of the plate is cut out and a part of the heat reflecting plate is cut out when viewed from the side surface.

In the invention according to the second aspect of the present invention, in the direction in which the sapphire ribbons pulled up from the die pack are arranged, the outside of the heat reflecting plate is covered with a plate-like member or the like, and the radiant heat received by the components near the die pack from the heater. The technical feature is that it has been adjusted.

  According to the technical features described above, the present invention can stabilize the growing conditions between the ribbons and prevent the occurrence of a side slip defect when simultaneously growing 10 or more sheets. This is an effect obtained by cutting out a part of the heat reflecting plate. That is, due to the melting point of alumina which is the material of the sapphire ribbon, the sapphire single crystal growth using the EFG method is performed under a high temperature condition of 2000 ° C. or higher. Along with this, the environment in the growth furnace has the two conditions that the alumina in the crucible melts and the alumina melt that is pulled up and cooled from the seed crystal continuously grows in the process. It must be satisfied throughout. In the present invention, these two conditions are satisfied by notching a heat reflecting plate that has conventionally been provided as a single continuous plate with respect to the large die pack used for the simultaneous growth of 10 or more sheets. More specifically, the heat reflection plate is laminated around the die pack to limit the range of radiant heat received from the heater arranged annularly on the outer periphery of the crucible, and the conventional technology that keeps the temperature gradient around the die pack constant. On the other hand, by making the stacking arrangement corresponding to the temperature drop of the die pack accompanying an increase in size large, only the center of the target die pack acts, the temperature gradient of the entire large die pack is stabilized regardless of the high temperature conditions. The effect of making it.

  In addition to the effects described above, the growth furnace used in the present application softens the radiant heat from the lid using the melt as a heat source, and passes the radiant heat from the heater disposed around the crucible, so that the most The high temperature portion of the temperature gradient is raised at the crucible center where the temperature is lowered, and the alumina melt in the die pack is kept at a high temperature. For this reason, in the growth furnace described in the present invention, it becomes possible to make the temperature of the tip end of the die pack where the crystal grows uniform regardless of the distance from the heater, and no side slip defect occurs for all sapphire ribbons grown from the die pack. Crystal growth can be performed under conditions. In addition, the uniform growth of the temperature condition can make the growth rate of the crystal grown on the die pack uniform. For this reason, it is possible to suppress the dispersion between the sapphire ribbons with respect to the speed during spreading, and to shorten the spreading time. Furthermore, in the growth furnace described in the present application, a stable temperature gradient is formed in the growth direction of each sapphire ribbon by arranging the heat reflecting plates in a stacked manner with a certain interval. For this reason, even when simultaneously growing a large number of sheets using the large die pack, it is possible to perform crystal growth with a stable width without causing a problem such as a reduction in the width of a part of the sapphire ribbon being grown.

  In addition, by using the second aspect of the present invention, the temperature condition can be more easily uniformed. This is due to the fact that the both ends of the sapphire ribbon arrangement direction where the temperature is highest are covered with plate-like members or the like when simultaneously growing a large number of sheets using a large die pack. That is, due to the structure covering the both end sides, in this embodiment, the temperature change on both end sides of the die pack that is moved up and down by the heater is moderate. For this reason, the temperature change of the heaters at the center of the die pack away from the heater and the temperature at both ends of the die pack is adjusted so that the temperature of the heater changes during growth depending on the furnace environment. It is possible to simultaneously adjust the growth conditions in a state where the variation of the above is suppressed and to simultaneously pull up the sapphire ribbons when the multiple sheets are simultaneously grown. Furthermore, due to the effect of simultaneously pulling up a large number of sheets, it is also possible to share a seed crystal used for growth and simplify the seed crystal holding mechanism.

As described above, by using the invention described in the present application, it is possible to stabilize the growing conditions between the ribbons when simultaneously growing a large number of sheets of 10 sheets or more, to prevent the occurrence of side slip defects, and to shorten the spreading time. In addition, it is possible to provide an EFG growing furnace capable of stabilizing the width of all sapphire ribbons to be grown at the die pack width.

Schematic of the EFG growth furnace used in the best mode of the present invention The whole perspective view of the die pack peripheral parts used in the best mode of the present invention FIG. 2 is an exploded perspective view of the peripheral parts of the die pack shown in FIG. Plan view of the die pack and heat reflecting plate shown in FIG.

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

  FIG. 1 is a schematic view of an EFG growth furnace used in the best embodiment of the present invention, FIG. 2 is an overall perspective view of the peripheral part of the die pack, FIG. 3 is an exploded perspective view of the peripheral part, and FIG. Are respectively plan views of the die pack and the heat reflecting plate. still,. About the heat | fever reflecting plate fixing structure and the support | pillar member for lid bodies in FIG. 1, description in the figure is abbreviate | omitted.

  As shown in FIG. 1, in the EFG growth furnace 1 described in the present embodiment, a die pack 5 in which a plurality of dies having plate-like voids are bundled is disposed in a crucible 7, and the alumina supplied into the crucible 7 is replaced with a heater 6. The sapphire ribbon of the sapphire ribbon is brought into contact with the single seed crystal lowered to the tip of the die pack and the molten alumina melt by filling the inside of the plate-shaped gap by capillary phenomenon. Train.

  By using such a structure, in the growth furnace 1 described in the present embodiment, a large number of sapphire ribbons can be simultaneously pulled up as the multi-sapphire ribbon 3. That is, in this embodiment, the multi-sapphire ribbon 3 made of a sapphire single crystal is grown by the simultaneous pulling using the common seed crystal 2 as a raw material. For this reason, while simplifying the support structure of the seed crystal 2, the effect of the simplification of the control at the time of crystal growth by sharing a pulling speed is also acquired. Further, in the present embodiment, a structure in which the lid body 10, the heat reflecting plate 11, and the cover 14 are provided near the tip end of the die pack where the crystal is formed by the pulling up is used. For this reason, when growing a plurality of sapphire ribbons, the temperature gradient of each sapphire ribbon is maintained in a state suitable for crystal growth, and the temperature change around the die pack by the heater 6 is moderated. It became possible to stabilize the growth rate.

  Next, an overall perspective view and an exploded perspective view of the periphery of the die pack in the present embodiment will be described with reference to FIGS. 2 and 3. As can be seen from FIG. 2, in this embodiment, the three-stage heat reflectors 11, 12, and 13 that are stacked and supported on the lid body are the center of the second-stage reflector 12 that is the middle plate from the bottom. A structure with a notch is used. For this reason, the radiant heat is directly irradiated from the heater 6 to the center of the die pack, and the radiant heat to be irradiated is limited to both ends of the die pack, thereby providing an effect of stabilizing the temperature gradient in the entire large die pack. I was able to. In addition, due to the effect, in this embodiment, in the growth furnace under a high temperature condition of 2000 ° C. or higher, the alumina melt was moved to the tip of the die pack due to alumina melting and capillary action in the crucible, and a seed crystal was used. It has become possible to satisfy the two conditions of cooling by pulling up and crystal growth in the process. Furthermore, in the present embodiment, the first-stage heat reflecting plate 11 is disposed over the entire circumference outside the die pack. As a result, radiant heat from the lid using the melt as a heat source is softened, the thermal effect on the die pack accompanying the increase or decrease in the amount of melt in the crucible is reduced, and temperature control stabilization around the die pack by the heater 6 is achieved. Could also get.

  In other words, in the present embodiment, only the third-stage reflector 13 corresponding to the center of the die pack is disposed above the die pack 5. Therefore, when simultaneously growing a large number of 10 or more sapphire ribbons, the radiant heat of the heater irradiated to the tip portion of the center of the die pack that is far from the heater 5 is adjusted, and the temperature gradient at the tip portion is adjusted. As with other tip portions, it was possible to maintain the sapphire ribbon in a state suitable for growth. More specifically, due to the structure in which the center of the second stage reflector is cut out, the melt in the center of the die pack in this embodiment is conveyed to the tip of the die pack while being directly heated by the radiant heat of the heater. . On the other hand, the growth of the sapphire ribbon requires a temperature gradient for forming a single crystal by aligning, cooling and fixing the molecules in the alumina melt as the seed crystal is pulled up. In this embodiment, the third stage reflector 13 is provided above the die pack 5 so that the temperature gradient is formed in the melt transported to the tip portion at the center of the die pack. The effect of stabilizing the growth conditions between the ribbons at the tip of the die pack used is imparted. Due to these effects, the EFG growth furnace described in the present embodiment prevents the occurrence of a side slip defect, stabilizes the width of all sapphire ribbons to be grown at the die pack width, and the speed during spreading between the sapphire ribbons. It became possible to reduce the spread and shorten the spreading time. The same effect can be obtained by removing the third-stage reflector from the same technical viewpoint and individually adjusting the height of each die.

  In addition to the above effects, as can be seen from the plan view of FIG. 4, in the present embodiment, the third-stage reflector 13 has a shape with a notch on the inside. As a result, the temperature gradient formed at the tip of the center of the die pack is set more finely, the variation between the ribbons is minimized, and the effect of improving the crystal quality in the simultaneous growth of a large number of sheets can be obtained. did it. Further, in the figure, a cover 14 is provided on the side surface of the second heat reflecting plate 12 so as to cover the up and down direction in which the grown sapphire ribbons are arranged, and the space between the heater and the die pack center is opened. In the center of the die pack away from the heater and both ends of the die pack close to the heater, the temperature changes for the heater are aligned, and the heater temperature that changes according to the furnace environment and growth condition It is possible to simultaneously pull up each sapphire ribbon. Furthermore, by sharing the seed crystal used for the growth when the large number of sheets are simultaneously pulled, the effect of simplifying the holding mechanism of the seed crystal could be obtained.

As described above, by using the invention described in the present application, it is possible to stabilize the growing conditions between the ribbons when simultaneously growing a large number of sheets of 10 sheets or more, to prevent the occurrence of side slip defects, and to shorten the spreading time. In addition, it has become possible to provide an EFG breeding furnace capable of stabilizing the width of all sapphire ribbons to be grown at the die pack width.

DESCRIPTION OF SYMBOLS 1 EFG growth furnace 2 Seed crystal 3 Multisapphire ribbon 4 Upper heat insulating material 5 Die pack 6 Heater 7 Crucible 8 Side surface heat insulating material 9 Bottom surface heat insulating material 10 Lid body 11 1st step heat reflector 12 2nd step heat reflector 13 3 Stage heat reflector 14 Cover 15 Prop member

Claims (2)

An EFG breeding furnace in which a part of the middle plate is removed and laminated among the heat reflection plates laminated on the side surface of the die pack.
  The EFG growing furnace according to claim 1, wherein the sapphire ribbon pulled up from the die pack has a structure covering the outside of the heat reflecting plate.

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