JP4386551B2 - Single crystal manufacturing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a single crystal manufacturing apparatus for growing a single crystal from a raw material in a melt state.
[0002]
[Prior art]
Silicon single crystals are mainly used as VLSI (Very large scale integrated circuit) substrate wafers. Thus, a semiconductor material is often used in a single crystal state, and single crystal manufacturing technology is indispensable for the development of semiconductor technology. Crystal growth is roughly divided into three types of growth mechanisms: gas phase to solid phase, liquid phase to solid phase, and solid phase to solid phase. Among these growth mechanisms, the CZ method (Czochralski method), FZ method (Floating zone method), and TSFZ method (Travelling solvent floating zone method) are used as single crystal manufacturing methods utilizing the growth mechanism from the liquid phase to the solid phase. Can be mentioned. In these methods, a single crystal having a predetermined orientation called a seed crystal is brought into contact with a raw material interface in a melt state, and a single crystal is grown using this seed crystal as a nucleus.
[0003]
In the single crystal growth furnace used for the FZ method and the TSFZ method, the crystal raw material rod is held on the upper main shaft provided on the upper side, and the seed crystal is held on the lower main shaft provided on the lower side. A melting zone is formed on the crystal raw material rod held on the upper main shaft by a high-frequency coil, an infrared intensive heating device or the like. The seed crystal held on the lower main shaft is rotated and moved up and down by the lower main shaft, and after coming into contact with the melting zone of the crystal raw material rod, the seed crystal is gradually pulled down to grow a single crystal.
[0004]
A method for holding a seed crystal in a conventional single crystal manufacturing apparatus will be described with reference to FIG. FIG. 10A is a schematic view of a seed crystal holder portion in a conventional single crystal manufacturing apparatus.
[0005]
As shown in FIG. 10A, the seed crystal holder 106 is screwed and fixed to the upper end of the lower main shaft 108. The seed crystal holder 106 includes a support fitting 104 that is a connection portion with the lower main shaft 108 and a holder 102 that holds the seed crystal 100.
[0006]
Usually, a high heat-resistant ceramic such as alumina is used for the holder portion 102, and a heat-resistant metal such as stainless steel is used for the support fitting 104. The holder fixing portion of the support fitting 104 has a cylindrical shape, and the holder portion 102 is pressed against the holder portion 102 to be fixed by winding a platinum wire 110 or the like. The seed crystal 100 has a substantially cylindrical shape and is pressed against the alumina tube of the holder 102 and wound with a platinum wire 110 or the like.
[0007]
At the time of crystal growth, the lower main shaft 108 is rotated, and the seed crystal 100 is rotated together with the seed crystal holder 106. In this state, the lower main shaft 108 is gradually pulled down to grow a single crystal.
[0008]
[Problems to be solved by the invention]
However, in the conventional single crystal manufacturing apparatus, the seed crystal 100 needs to be set in a state where the crystal axis is completely coincident with the rotation axis of the lower main shaft 108, that is, the center axis of the seed crystal holder 106. When the growth is started in a state where the crystal axis of the seed crystal 100 does not completely coincide with the rotation axis of the lower main shaft 108, the seed crystal 100 protrudes into a low temperature portion, so that the crystal is not in the vertical direction and the outer peripheral portion having a low temperature. It will stick out and begin to grow.
[0009]
Some seed crystals 100 are variable in diameter, constricted, or tapered. In such a case, the crystal axes cannot be completely aligned by simply pressing the seed crystal 100 against the alumina tube of the holder 102.
[0010]
FIG.10 (b) is an expanded sectional view which shows the holding method of the seed crystal in the conventional single crystal manufacturing apparatus. Conventionally, as shown in FIG. 10 (b), an operation of aligning the core while finely adjusting a spacer 112 such as a platinum wire between the alumina tube of the holder 102 and the seed crystal 100 has been performed. However, this work requires a lot of labor and requires skill, which causes the work efficiency of the crystal growth preparation work to deteriorate. In addition, as described above, it is a factor that lowers the yield of crystal growth.
[0011]
In order to solve the above-described problems of the prior art, it is conceivable that the seed crystal having a non-constant shape is ground and shaped into a constant shape. In the case of a very brittle crystal, it is difficult to process itself.
[0012]
In addition, an alignment mechanism such as an XY stage or a goniometer may be incorporated in the main shaft portion or the seed crystal holder portion. However, it cannot be used because it becomes extremely hot during crystal growth and seizure occurs.
[0013]
An object of the present invention is to provide a single crystal manufacturing apparatus that improves the yield of crystal growth by increasing the efficiency of work before starting the growth of crystals and increasing the centering accuracy of seed crystals.
[0014]
[Means for Solving the Problems]
The purpose is to rotate a single crystal raw material holder for holding a single crystal raw material, a heating means for forming a melting zone in the single crystal raw material, a seed crystal holder for holding a seed crystal, and the seed crystal holder. A single-crystal manufacturing apparatus that rotates the seed crystal and grows the crystal from the melt zone while contacting the seed crystal with the melt zone of the single crystal raw material. A ball seat structure for connecting an end of the rotating shaft and an end of the seed crystal holder by a ball seat, and changing an axial direction of the seed crystal with respect to the rotating shaft; and the seed with respect to the rotating shaft This is achieved by a single crystal manufacturing apparatus having fixing means for fixing the seed crystal holder in a state where the axial direction of the crystal is changed.
[0015]
The seed crystal manufacturing apparatus described above further includes a chuck mechanism formed coaxially with the rotation shaft, and the center of the upper end of the seed crystal is not misaligned by closing the chuck mechanism and holding the seed crystal at the tip. You may make it change the axial direction of the said seed crystal holder to a position .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
The overall configuration of the single crystal manufacturing apparatus according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a front view of the single crystal manufacturing apparatus according to the present embodiment.
[0017]
The single crystal manufacturing apparatus of this embodiment is an infrared concentration heating furnace used for the FZ method and the TSFZ method. In the single crystal manufacturing apparatus of the present embodiment, the cylindrical transparent partition wall 18 is vertically fixed by the transparent partition wall lower holding unit 20 and the transparent partition wall upper holding unit. Inside the transparent partition 18, the upper main shaft 10 is disposed through the transparent partition upper holding portion 24, and the lower main shaft 14 is disposed through the transparent partition lower holding portion 20. Both the upper main shaft 10 and the lower main shaft 14 can be moved up and down and rotated. During normal crystal growth, a gas such as argon or oxygen is introduced into the transparent partition wall 18 from the atmospheric gas inlet 22 of the transparent partition wall lower holding portion 20. The atmospheric gas is exhausted from the atmospheric gas outlet 26 of the transparent partition upper holding part 24.
[0018]
An infrared concentrated heating device 28 is attached outside the transparent partition wall 18. The infrared central heating device 28 has an ellipsoidal mirror 29 therein. One focal point 32 of the ellipsoidal mirror 29 is located on the central axes of the upper main shaft 10 and the lower main shaft 14 in the transparent partition wall 18.
[0019]
A halogen lamp 30 is placed at the other focal point 33 of the ellipsoidal mirror 29, and the light is condensed on the focal point 32 of the ellipsoidal mirror 29, and heating at the focal point 32 can be performed.
[0020]
In the infrared concentrated heating furnace described above, the crystal raw material rod 12 is held at the lower end of the upper main shaft 10. A seed crystal holder portion 16 is fixed to the upper end of the lower main shaft 14. On the crystal raw material rod 12, a melting zone 34 is formed by a focal point 32 which is a heating portion of the infrared concentrated heating device 28. The seed crystal 31 is fixed to the seed crystal holder portion 16. The seed crystal 31 held by the seed crystal holder portion 16 is pulled down while rotating after contacting the melt zone 34 by the lower main shaft 14, thereby growing a single crystal. The growth process of the single crystal is monitored by the CCD camera 36. It is also possible to monitor the growth process of the single crystal using a projection screen or the like.
[0021]
Next, details of the seed crystal holder portion 16 in the present embodiment will be described with reference to FIG. FIG. 2 is a schematic view showing the configuration of the seed crystal holder unit 16 according to the present embodiment.
[0022]
The seed crystal holder portion 16 in the present embodiment includes a support rod 40 having a sphere portion 38 formed at the lower end and a support metal base portion 42 having a concave structure with a spherical upper surface. A ball seat is formed by fitting the ball portion 38 of the support rod 40 into the spherical surface of the support bracket base portion 42. The support rod 40 can freely change the angle of the central axis with respect to the support fitting base 42 with the center of the ball portion 38 as a fulcrum. The support bar 40 is fastened and fixed to the support metal base 42 by the cap nut 44. The support metal base 42 has a structure having a screw 46 at the bottom. Thereby, the support metal base 42 is fixed to the upper end of the lower main shaft 14.
[0023]
Next, the seed crystal centering operation of the single crystal manufacturing apparatus according to the present embodiment will be described with reference to FIGS. FIG. 3 is a schematic diagram showing the state of the seed crystal before and after the centering operation in the present embodiment.
[0024]
First, as shown in FIG. 3A, the seed crystal holder 50 is fixed to the support rod 40 with a platinum wire 52 or the like in the same manner as in the prior art. Similarly, the seed crystal 31 is fixed to the seed crystal holder 50 by a platinum wire 52 or the like. At this time, it is not necessary to perform a centering operation using a spacer or the like as in the prior art.
[0025]
Subsequently, as shown in FIG. 2, the ball portion 38 of the support rod 40 is fitted into the spherical concave structure on the upper side of the support fitting base portion 42, and the cap nut 44 is tightened to be temporarily fixed. Further, the seed crystal holder 50 is fixed to the lower main shaft 48 by the screw 46 of the support metal base 42. Thereafter, the cap nut 44 is slightly loosened so that the position of the center of the upper end of the seed crystal 31 can be finely adjusted, and the seed crystal holder 50 is fixed by gradually changing the angle of the center axis with the center of the ball portion 38 as a fulcrum. The lower main shaft 14 or the seed crystal holder 50 is rotated. As a result, as shown in FIG. 3B, after the seed crystal 31 is aligned at a position where the center of the upper end of the seed crystal 31 is not misaligned, the cap nut 44 is tightened and fixed securely. This aligns the core of the seed crystal 31.
[0026]
As described above, according to this embodiment, since the seed crystal holder having the ball seat is used for the support metal part, it is not necessary to adjust the center position of the upper end of the seed crystal with the spacer as in the past. Since it is not necessary to perform the difficult centering work up to now, the work before the start of crystal growth is made more efficient. Moreover, since the centering accuracy can be increased, the yield of crystal growth can be improved.
[0027]
In the above embodiment, the support metal base 42 is fixed to the lower main shaft 14 by screwing, but a ball seat may be directly formed on the lower main shaft 14 as shown in FIG. That is, the ball portion 38 of the support rod 40 may be fitted into a spherical concave structure formed directly on the upper end of the lower main shaft 14 and fixed by the cap nut 44.
[0028]
In the above-described embodiment, the seed crystal holder 50 is fixed to the support rod 40. However, as shown in FIG.
[0029]
[Second Embodiment]
The configuration of the single crystal manufacturing apparatus according to the second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the seed crystal centering operation in the single crystal manufacturing apparatus according to the first embodiment described above is automated by using a jig for centering the seed crystal described below.
[0030]
FIG. 6 is a cross-sectional view showing a state in which the centering device 60 is fixed to the infrared central heating furnace 58 main body of the single crystal manufacturing apparatus of the present embodiment. The centering device 60 includes a chuck mechanism portion 61 and an attachment portion 63. The centering device 60 is directly fixed to the infrared central heating furnace 58 from which the infrared central heating device 28 and the transparent partition 18 have been removed using the transparent partition holder 62. A chuck 64 of the chuck mechanism 61 surrounds the seed crystal holder 16 having a ball seat. Here, the central axis of the chuck mechanism portion 61 and the central axis of the lower main shaft 14 coincide with each other.
[0031]
Next, details of the configuration of the chuck mechanism 61 will be described with reference to FIG. FIG. 7 is a top view and a cross-sectional view of the chuck mechanism 61 of the centering device 60. As shown in the top view of FIG. 7A, a chuck 64 is disposed around the center axis of the lower main shaft 14. An alignment cap nut 68 is placed on these chucks 64. As shown in the sectional view of FIG. 7B, a chuck support 62 is fixed on the mounting portion 61, and a chuck 64 is attached to the chuck support 62 via a spring 66. The chuck 64 has a tapered outer portion. The chuck 64 is pushed upward by a spring 66. Thus, the outer tapered portion of the chuck 64 is pressed against the inclination of the inner surface of the centering cap nut 68 that covers the chuck 64 from above. The centering cap nut 68 is tightened downward with respect to the attachment portion 63.
[0032]
Next, the operation of the chuck mechanism 61 of the centering device 60 will be described with reference to FIG.
[0033]
As described above, the outer tapered portion of the chuck 64 is pressed against the inner surface of the centering cap nut 68 by the spring 66. Therefore, when the centering cap nut 68 covering the upper portion of the chuck 64 is tightened, the chuck 64 is pressed downward by the centering cap nut 68, and the central axis of the chuck mechanism 61, that is, the lower main shaft 14. It gradually closes around the central axis. When the centering cap nut 68 is loosened, the chuck 64 is pushed upward by the spring 66, so that the chuck shaft 61 is opened around the central axis of the chuck mechanism 61, that is, the central axis of the lower main shaft 14. The centering operation according to the present embodiment uses such a chuck mechanism.
[0034]
Next, the procedure of the centering operation using the centering device 60 having the chuck mechanism 61 will be described.
[0035]
First, the seed crystal 31 is temporarily fixed to the seed crystal holder portion 16 having a spherical seat, and the seed crystal holder portion 16 is fixed to the lower main shaft 14. At this time, the operation of the ball seat is left free. Next, the lower main shaft 14 is moved up and down and adjusted so that the chuck 64 of the centering device 60 contacts the seed crystal 31. Thereby, centering by the chuck 64 becomes possible.
[0036]
When the alignment nut 68 is tightened in this state, the chuck 68 is closed around the central axis of the chuck mechanism 61, that is, the central axis of the lower main shaft 14. Since the seed crystal holder portion 16 is freely moved by the ball seat, the center position of the seed crystal 31 can be automatically aligned with the center axis of the lower main shaft 14 by tightening the alignment nut 68. Finally, the seed crystal 31 is fixed at a desired center position by the chuck 64. In this state, the cap nut 44 of the seed crystal holder portion 16 is tightened to fix the angle of the ball seat. In this way, the centering operation of the seed crystal 31 by the centering device 60 is completed.
[0037]
The above-described centering device 60 does not shift the position of the seed crystal 31 even when it is attached and detached. Therefore, after the centering operation is completed, the centering device 60 is once removed from the transparent partition wall lower holding portion 20, the crystal raw material rod 12 is attached to the upper main shaft 10, and then the transparent partition wall 18 and the infrared concentrated heating device 28 are reattached. The crystal growth process can be started quickly.
[0038]
As described above, in this embodiment, the centering operation of the seed crystal is automatically performed by using the centering device having the chuck mechanism, and a constant centering operation without individual difference in the centering accuracy becomes possible.
[0039]
In the above-described embodiment, the centering device 60 is fixed to the infrared central heating furnace 58 using the transparent partition holding unit 62. However, as shown in FIG. 8, the chuck mechanism 61 of the centering device 60 is used. The lower main shaft 14 may be inserted into the mounting portion 70 attached to the lower portion, and the centering device 60 may be fixed to the lower main shaft 14 with screws 72.
[0040]
Also in this case, the center axis of the chuck mechanism 61 of the centering device 60 and the center axis of the lower main shaft 14 coincide with each other. Further, the height of the chuck mechanism 61 with respect to the seed crystal 31 is adjusted at the mounting position of the centering device 60 with respect to the lower spindle 14. The subsequent procedure for centering the seed crystal 31 can be performed in substantially the same manner as in the above embodiment.
[0041]
First, the seed crystal 31 is temporarily fixed to the seed crystal holder 16 having a ball seat, and the seed crystal holder 16 is fixed to the lower main shaft 14. At this time, the operation of the ball seat is left free. Next, the screw 72 is loosened to move the mounting position of the centering device 60 up and down, and the portion of the centering device 60 corresponding to the chuck 64 relative to the seed crystal 31 is adjusted. Thereby, the centering can be positioned by the position of the chuck 64. When positioned by the chuck 64, the screw 72 is tightened to securely fix the centering device 60 to the lower main spindle 14.
[0042]
Subsequently, when the alignment nut 68 is tightened, the chuck 68 is closed around the central axis of the lower main shaft 14, that is, the rotation axis at the time of crystal growth. The seed crystal 31 can be aligned with the center position by tightening the alignment nut 68 with the ball seat of the seed crystal holder portion 16. Finally, the seed crystal 31 is fixed at the position of the core by the chuck 64. In this state, the cap nut 44 of the seed crystal holder portion 16 is tightened to fix the angle of the ball seat. This completes the centering operation of the seed crystal 31 when the centering device 60 is fixed to the lower main shaft 14.
[0043]
After the centering is completed, the screw 72 is loosened to remove the centering device 60 from the lower main shaft 14, the crystal raw material rod 12 is attached to the upper main shaft 10, the transparent partition wall 18 and the infrared heating device 28 are attached, and the single crystal is grown. Start.
[0044]
Further, not only the centering device 60 is used while being fixed to the infrared central heating furnace 58, but the centering device 60 may be used alone as shown in FIG. In this case, the shaft 76 is fixed to the independent base 74 by screws 76. By loosening the screw 78, the shaft 76 can be moved up and down in the vertical direction. The seed crystal holder portion 16 is attached to the upper end of the shaft 76 with a screw 46 of the support bracket base portion 42. A chuck mechanism 61 similar to that of the above-described embodiment is formed on the base 74 around the central axis of the shaft 76.
[0045]
The centering operation when the above-described centering device 60 is used alone will be briefly described. First, the seed crystal 31 is temporarily fixed to the seed crystal holder 16 having a ball seat, and the seed crystal holder 16 is fixed to the shaft 76 with the screw 46 of the support metal base 42. At this time, the operation of the ball seat is left free. Next, the screw 78 is loosened, the shaft 76 is moved up and down, and the portion of the chuck 64 that contacts the seed crystal 31 is adjusted. Thereby, the lead comes out at the position of the chuck 64. Here, the screw 78 is tightened to fix the position of the shaft 76. The subsequent centering operation is performed by tightening the centering cap nut 68 as in the above embodiment.
[0046]
After centering the seed crystal 31 using the centering device 60 alone, the centering cap nut 68 is loosened, the seed crystal holder 16 is removed from the shaft 76 together with the support metal base 42, and the infrared concentrated heating furnace 58 is removed. It fixes to the upper end of the lower main shaft 14 with the screw 46 of the support metal base 42. Since the seed crystal 31 fixed at this time is in a state of being centered with respect to the central axis of the lower main shaft 14, it is possible to pass through the process of growing a single crystal as it is.
[0047]
[Modified Embodiment]
The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, an infrared concentrated heating device is used to form the melting zone, but the invention is not limited to the infrared concentrated heating device, and a heating coil is wound around the raw material crystal rod, and a high-frequency current is applied to this. May be heated by an eddy current induced by a high-frequency magnetic flux generated by a coil to form a melting zone. Alternatively, a heating body may be formed around the crystal rod with an electric conductor, and direct current and alternating current may be passed through the heating body and heated to form a melting zone. Alternatively, the melting zone may be formed by directly partially heating the crystal material rod with an electron beam.
[0048]
Moreover, in the said embodiment, although it has the arrangement | positioning by which the crystal raw material stick | rod was fixed to the upper main axis | shaft and the seed crystal was fixed to the lower main axis | shaft, these arrangement | positioning relations may be upside down. In this case, a single crystal is grown by pulling the seed crystal while rotating.
[0049]
In the above embodiment, the single crystal growth is performed by the FZ method and the TSFZ method. However, other CZ methods that perform crystal growth while rotating the seed crystal by contacting the seed crystal with the single crystal raw material in the melt state. Such a method may be used. That is, the seed crystal may be centered with respect to the rotation axis at the time of crystal growth in the CZ method using a seed crystal holder having a spherical seat and its centering device.
[0050]
【The invention's effect】
As described above, according to the present invention, since the seed crystal holder having the ball seat is used for the support metal part, it is not necessary to adjust the center position of the upper end of the seed crystal with a spacer as in the past. Therefore, the efficiency of work before starting the growth of crystals and the centering accuracy of the seed crystals can be increased. Furthermore, by combining a seed crystal holder having a ball seat on the support bracket and a centering device having a chuck mechanism, automatic centering work with no individual difference in centering accuracy is possible, and the yield of crystal growth is increased. Can be improved.
[Brief description of the drawings]
FIG. 1 is a front view of a single crystal manufacturing apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic view of a seed crystal holder part in the single crystal manufacturing apparatus according to the first embodiment of the present invention.
FIG. 3 is a schematic diagram showing the state of the seed crystal before and after the centering operation in the first embodiment of the present invention.
FIG. 4 is a schematic view when a ball seat is formed on the lower main shaft according to a modification of the first embodiment of the present invention.
FIG. 5 is a schematic view showing a part in which a support bar and a seed crystal holder are integrated according to a modification of the first embodiment of the present invention.
FIG. 6 is a cross-sectional view illustrating a state in which a centering device is fixed using a transparent partition wall holder according to a second embodiment of the present invention.
FIG. 7 is a diagram showing details of a centering device according to a second embodiment of the present invention.
FIG. 8 is a cross-sectional view showing a state in which a centering device according to a modification of the second embodiment of the present invention is directly fixed to a lower main shaft.
FIG. 9 is a sectional view showing a state in which a centering device according to a modification of the second embodiment of the present invention is used alone.
FIG. 10 is a view showing a single crystal holder part in a conventional single crystal manufacturing apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Upper spindle 12 ... Seed crystal raw material rod 14 ... Lower spindle 16 ... Seed crystal holder part 18 ... Transparent partition 20 ... Transparent partition lower part holding part 22 ... Atmosphere gas inlet 24 ... Transparent partition upper part holding part 26 ... Atmosphere gas outlet 28 ... Infrared concentrating heating device 29 ... Ellipsoidal mirror 30 ... Halogen lamp 31 ... Seed crystal 32 ... Focus 33 ... Focus 34 ... Melting zone 36 ... CCD camera 38 ... Ball portion 40 ... Support rod 42 ... Support bracket base 44 ... Cap nut 46 ... Screw 50 ... Seed crystal holder 52 ... Platinum wire 54 ... Support rod-seed crystal holder integrated part 58 ... Infrared concentration heating furnace 60 ... Centering device 61 ... Chuck mechanism 62 ... Chuck support 63 ... Mounting part 64 ... Chuck 66 ... Spring 68 ... Alignment cap nut 70 ... Mounting portion 72 ... Screw 74 ... Base 76 ... Shaft 78 ... Screw 100 ... Seed crystal 102 ... Holder 104 ... Support metal fitting 106 ... Seed crystal holder 1 8 ... lower spindle 110 ... platinum wire 112 ... spacer

Claims (2)

A single crystal raw material holder for holding a single crystal raw material, a heating means for forming a melting zone in the single crystal raw material, a seed crystal holder for holding a seed crystal, and rotating the seed crystal holder to form the seed crystal A single-crystal manufacturing apparatus that rotates the seed crystal and grows a crystal from the melt zone while contacting the seed crystal with the melt zone of the single crystal raw material,
A ball seat structure that connects an end portion of the rotating shaft and an end portion of the seed crystal holder by a ball seat, and changes an axial direction of the seed crystal with respect to the rotating shaft;
And a fixing means for fixing the seed crystal holder in a state where the axial direction of the seed crystal is changed with respect to the rotating shaft. The seed crystal production apparatus according to claim 1,
And further comprising a chuck mechanism formed coaxially with the rotating shaft, and the seed crystal holder is held at a position where the center of the upper end of the seed crystal is not misaligned by closing the chuck mechanism and holding the seed crystal at the tip. An apparatus for producing a single crystal, characterized by changing the axial direction of.

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