JPS5834440B2 - Tanketshuyo no seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a single crystal, particularly a method for producing a single crystal in which crystal growth can be easily controlled by a pulling method from a molten state or a floating melt zone method.

Conventionally, the growth of crystals such as semiconductor single crystals or optical single crystals has been controlled by those skilled in the art while monitoring the growing crystal directly or through an optical lens system with the naked eye.

Therefore, there were drawbacks such as variations in crystal growth depending on the level of skill.

This invention uses a single crystal seed with a desired growth direction from the molten state of the crystal raw material, particularly at a high temperature above the melting point.
When growing a single crystal in the same direction as this, a new single crystal method is developed that controls crystal growth while monitoring whether the crystal grows in the desired growth direction and maintains the single crystal state. A manufacturing method is provided.

This invention will be explained below with reference to the drawings.

FIG. 1 is a cross-sectional view for explaining one embodiment of the present invention, and FIG. 2 is a plan view of FIG. 1.

In Figures 1 and 2, 1 is an electron gun for generating X-rays, 2 is an X-ray source (C rotating growing crystal, 6 an internal crucible (e.g. quartz crucible);
7 is an external crucible (for example, a carbon crucible); 8 is a suitable heater for supplying heat to the crystal raw material or the external crucible; for example, a high-frequency heating coil 9 connected to a high-frequency oscillator is brought into a molten state by the heater; crystal raw material, 10
1 shows the entire counting circuit including a light receiving slit, 11 an X-ray detector, and 12 an intensifier director and a recorder.

13 is an incident characteristic X-ray, 14 is a diffraction characteristic X-ray, and 15 is a tangential plane in contact with the side surface of the growing crystal 5.

When an electron source generated from an electron gun 1 collides with an X-ray source (incoming radiation source) 2 while being accelerated with energy higher than a certain excitation voltage, incident characteristic X-rays 13 having a specific wavelength are generated.

After narrowing this down to an appropriate irradiation area with a slit 3, it is guided to the crystal growth area with an irradiation barrel 4, and the incident angle θ formed with the back punched surface 15 of the side surface of the growing crystal 5 suppresses X-ray diffraction. The rotating growing crystal 5 is continuously irradiated with incident characteristic X-rays 13 so as to satisfy the Bragg condition.

Here, d is the distance between the lattice planes (hh, l) to be used for X-ray diffraction in the growing crystal 5, and the distance between the growth direction of the growing crystal <h'h'l'> and the lattice plane. Select so that they are parallel to each other.

That is, hh'+hh'+l l'=0 1 In equation (1), "person" is the wavelength of the incident specific X-ray 13 from the X-ray source 2.

In this case, when the lattice plane (hhl) becomes parallel to the tangential plane 15, the incident characteristic
Due to hhN, the beam is diffracted in a direction in which the angle (diffraction angle) with the tangential plane 16 is equal to the incident angle θ, producing a diffraction characteristic X-ray 14.

This diffraction characteristic X-ray 14 is detected by an X-ray detector 11, and an appropriate counting circuit 12 records the intensity of the diffraction incident ray.

Therefore, for example, if the growing crystal 5 has a growth direction <h'h'
i'>, parallel to the lattice planes, and having the same distance d between lattice planes, the incident characteristic X-ray 13 enters the rotating growing crystal 5 at an incident angle When incident at θ, a diffraction characteristic X-ray 14 is generated every time the equivalent lattice plane (hhl) becomes parallel to the tangential plane 15.

The intensity of the diffracted X-rays recorded at this time is shown in Figure 3a.
For example, if there are three equivalent lattice planes (hhl) parallel to the growth direction <h'h'1'> of the growing crystal 5, three diffraction peaks will be recorded within time t1. It should be.

Further, since the time t1 is the time required for one rotation of the growing crystal 5, the rotation speed R is expressed as.

Next, the effects of this invention will be explained.

First, as mentioned above, if the grown crystal 5 maintains the desired single crystal state, the rotational speed of the grown crystal 5 can be monitored.

That is, if a disturbance occurs in the rotational number or rotational speed, this will result in a change in the elapsed time between the peaks of diffracted X-rays, and this can be used to control crystal growth.

The second effect is that it is possible to monitor whether or not the grown crystal 5 maintains the desired single crystal state while continuing to grow.

It cannot be determined whether the normally grown crystal 5 is a single crystal until after the growth operation has been completed, the grown crystal has cooled down, and has been removed from the growth apparatus.

According to this invention, for example, if the single crystal state of the growing crystal 5 collapses during growth and twin crystals are generated, the period between the rotation peaks will be suddenly disturbed as shown in FIG.

For example, if the single crystal state collapses and becomes polycrystalline, the diffraction peak intensity will decrease or multiple weak peaks will appear from the grain boundary region, as shown in Figure 3C. This appears as a disappearance of the peak and an increase in Paccland.

The growth state of a single crystal can be easily monitored and controlled by utilizing the period l or sudden disturbance in intensity of these diffraction heaters.

Furthermore, even if the growing crystal 5 changes to a twin or polycrystalline state during the process, these twins or polycrystals are controlled to descend into the molten crystal raw material 9, and the crystals are dissolved and grown again. If this is done, all of the grown crystal 5 can be made into a single crystal.

A third advantage is that the growth direction can be calibrated.

In other words, the growth direction is the desired direction <h'h'l'>
If there is a slight deviation from the peak, the diffraction intensity from the growing crystal 5 will be non-uniform as shown in Figure 3d. The strength should be uniform.

A fourth advantage of using X-rays is that by their nature, elements with relatively small masses such as carbon, quartz, etc.
As shown in the embodiment shown in FIG. 1, it is possible to sufficiently transmit holon oxide, etc. without reducing the strength. It can be applied to the crystal growth of germanium, gallium, etc., and even if the molten crystal raw material 9 is covered with molten holon oxide in order to prevent phosphorus from evaporating during the crystal growth of gallium phosphorus. Through this, growth status can be monitored.

The fifth advantage is that, due to the nature of X-rays, they travel in a straight line with almost no change in refractive index depending on the atmospheric gas, so there is no need to make large incidental equipment or modifications to the crystal growth equipment that would make crystal growth operations difficult. be.

In addition, the sixth advantage is shown in Fig. 2, where the light receiving slit 10
The diameter of the grown crystal 5 can be controlled by selecting the position of the crystal.

In other words, if the diameter of the growing crystal 5 changes, the characteristic diffraction X-ray 1
4 shifts in either the left or right direction with respect to the light-receiving slit 10, resulting in a decrease in the diffraction intensity, so monitor this and change the growth conditions so that the diffraction intensity increases again to increase the diameter of the grown crystal 5. control is possible.

As described above, the present invention provides a method for producing single crystals that does not require any skill at all, and has extremely significant industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view for explaining an embodiment of the method for producing a single crystal according to the present invention, and FIG. 2 is a top view of FIG. 1. In Figures 1 and 2, 1 is an electron gun, 2 is an X-ray source (
3 is a slit, 4 is an irradiation cylinder, 5 is a growing crystal, 6 is an internal crucible, 7 is an external crucible, 6 is a heater, 9 is a crystal raw material in a molten state, 10 is a light receiving slit, 11
12 is an X-ray detector, 12 is an X-ray counting circuit, 13 is an incident characteristic X-ray, 14 is a diffraction characteristic X-ray, and 15 is a tangent plane to the crystal side surface. FIG. 3 is an example showing the time course of the intensity of diffracted X-rays from the growing crystal 5, where a is when the single crystal state is maintained, b is
d indicates a case where the single crystal state collapses and twin crystals occur during growth, C indicates a case where polycrystalization occurs during growth, and d indicates a case where the growth direction of the growing crystal is slightly shifted.

Claims (1)

[Claims] 1. By continuously irradiating a rotating single crystal during growth with characteristic X-rays and measuring the intensity of the diffracted X-rays, it is possible to monitor the growth state of the single crystal, control the rotation speed, or calibrate the growth direction. A method for producing a single crystal, characterized by growing the crystal while performing the steps.