JPS5945990A - Method for growing single crystal - Google Patents

Abstract

PURPOSE:To manufacture a high-quality single crystal, in high efficiency, by using a seed crystal fitted in a specific pipe in the growth of a single crystal using the Czochralski method, thereby facilitating the seeding and the growth of the neck part of the single crystal. CONSTITUTION:The pipe 17 for holding the seed crystal 18 is made of a material having higher melting point than the temperature of the molten crystal component 19 and inert to the molten liquid 19. The pulling shaft 15 is bonded to the cylindrical chuck 11 with the pin 14, and the pipe 17 fitted with the seed crystal 18 is attached to the chuck 11 with the pin 16. The lower end of the pipe 17 is made lower than the lower end 18' of the seed crystal by about 10mm.. The shaft 15 is lowered until the lower end 18' of the seed crystal is brought into contact with the surface of the molten liquid 19 to effect the seeding, and the shaft is pulled up at a definite speed to grow the neck part 20' of the single crystal in the pipe 17. The pulling motion is continued while decreasing the temperature of the molten liquid 19 gradually to enlarge the diameter of the single crystal and form the shoulder part. When the diameter of the shoulder reaches the desired level, the temperature of the molten liquid is maintained to the state to start the growth of the body part of the single crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a method for growing a single crystal, and particularly to a method for growing a negative part of a Czochralski crystal.

(b) Background of the technology The main methods for pulling and growing single crystals include the floating zone method, in which a polycrystal is melted to the 11μ order from one end and a single crystal is formed at one end of the seed crystal, and the crystal component fusion method. There is a Czochralski method in which a single crystal is grown on a predetermined surface of a seed crystal immersed in a liquid, and LiT
Oxide single crystals such as aO5 are widely grown by the Czochralski method.

(e) Prior art and problems Figure 1 is a schematic diagram of an oxide single crystal growth apparatus using the Czochralski method.
A heating high-frequency coil 4 that faces crucible 2 and is wound around the outside of ceramic tube 3, a crystal pulling Qy axis 5 that can rotate and move up and down, and It includes a weight sensor 6 attached to the upper end and a chuck 7 attached to the lower end of the shaft 5.

In such an apparatus 1, a predetermined high-frequency 'tJl'' current is passed 17 through the high-frequency coil 4, and j) the crystal material in the i-pit 2 is melted to form a melt 8, and the upper end is fixed to the chuck 7 to form a cylindrical polar crystal. The lower end of 9 is immersed in the surface of melt 8, the melt 8 is controlled to the crystal growth temperature, and the shaft 5 is pulled up at an appropriate speed while being rotated -If, a single crystal 10 is obtained in the seed crystal 9. At that time, the M total sensor 6 detects that the lower surface of the good crystal 9 comes into contact with the surface of the melt 8 (commonly known as "grabbing"), and the surface tension of the liquid 8 is applied to the surface of the fci'm crystal 9. In addition to detecting changes in the weight of the shaft 5 and shaft 5, the pulling speed of the shaft 5 and the temperature of the melt 8 are controlled to detect the weight of the single crystal 1O in the growing process.

And we grow madder quality single crystals with few defects, especially in the case of sapphire M.
.

However, in the process of growing the sleeves and the neck 10'', the weight change detected by the weight sensor 6 was minute, and there was a drawback that the operator's empirical judgment had to be correct.

(d) Object of the invention The object of the invention is to provide a method for growing single crystals that eliminates the above-mentioned drawbacks.

(c) Structure of the invention
・Crystal cross sections 1h1 and e are made by protruding a pipe having the same inner cross section by an appropriate amount beyond the crystal rJ surface.
The ffl viscous crystall adheres to the T-]JJIX, and the η1 crystal that melts on the surface has grown a neck inside the pipe.
fJ and (f) Fruits of the Invention & Examples Below, Figures 2 and 3 are related to an embodiment of the present invention method.
[Zl will be explained.

Figure 2 shows part z2, a partially cutaway side view of a seed crystal fixed to the chuck of the crystal growth device, and Figure 3 shows part 1. [11
It is.

Ei: 2 At t=1, a cylindrical chuck 11 corresponding to the chuck 7 described above has a pair of through holes 12 and 13 with a central through hole W tffi, and a bottle inserted into the through hole 12 is 14 is a shaft 15 corresponding to the aforementioned shaft 5 and a chuck 1
The pin 16 is fitted into the through hole 13 and the seed crystal 18 into which the pipe 17 is fitted is connected to the chuck 11. However, the pipe 17 that protrudes an appropriate amount (for example, 10 cm) or downward from the single crystal melt surface 18' of the crystal 18,
The melting point Th is 1 degree higher than the melt (19 in Figure 3) temperature.
It is made of a material that does not react with the melt, such as iridium, which is the same as the melt tank 11, and the inner shape of the cross section is the same as the cross section of the seed crystal 18.

The crystal pulling shaft 15 with the seed crystal 18 fixed thereon is lowered so that the lower surface 18' of the crystal is in contact with the surface of the melt 19, and then the shaft 15 is pulled upward at a constant single crystal growth rate of 79i. increase. At this time, the single crystal neck r'' is blocked by the inner wall of the pipe 17 and can be formed without spreading beyond the inner wall.

The opening in FIG. 3 is the second step of growing a single crystal, and the single crystal neck 2 is formed by extending the lower surface 18' of the seed crystal 18 downward.
After growing 0' (while continuing to pull the single crystal 18, the temperature of the melt 199 is gradually lowered, the single crystal 20 gradually spreads laterally as shown in the figure, and the tom reaches a predetermined value (for example, the diameter When the temperature reaches about 75), *'i! If you maintain the liquid temperature 9 of 19, the torso will grow.

(g) As described in detail, according to the present invention, the seeding for growing a single crystal from a seed crystal is performed under suitable timing conditions, and the single crystal has at least a length of pipe protruding from the lower surface of the seed crystal. Since a crystal neck is formed, the Czochralski method is extremely effective in making it possible to grow a single crystal without relying on an expert.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an oxide single crystal growth apparatus using the Czochralski method, Fig. 2 is a partially cutaway side view of a seed crystal fixed to a shichak according to an embodiment of the present invention, and Fig. 3 2 is a diagram for explaining the main process of growing a single crystal using the seed crystal shown in FIG. 2. FIG. In the figure, 1 is a single crystal growth device using the Czochralski method, 2 is a crucible, 3 is a ceramic tube, 5.15 is a crystal pulling shaft, 7.11 is a chuck, 8°19 is a crystal melt, 9 .18 is a seed crystal, 10.20 is a single crystal, 10'r,
The large diameter part of the crystal, 10'', 20' is the uniaxial crystal part, 17 is the iridium pipe, and 18' is the lower surface of the crystal 18.

Claims (1)

[Claims] When growing a single crystal from a seed crystal by immersing it in a melt,
A pipe made of a material that has a melting point higher than the melt temperature and does not react with the melt, and has an inner cross section that is approximately the same shape as the cross section of the rod-shaped rod crystal, is made to protrude by an appropriate amount from the crystal growth surface. A method for growing a single crystal, characterized in that the method comprises: