JPS63170296A - Detection of runout width of single crystal silicon in cz furnace - Google Patents

Abstract

PURPOSE:To prevent the deterioration of single crystal silicon and to obtain the high-quality single crystal silicon, by detecting the runout width of the single crystal silicon during growth in a CZ furnace by using a one-dimensional CCD camera so that the quick correction of the runout of the single crystal is permitted. CONSTITUTION:The one-dimensional CCD camera 7 is disposed toward the inside of the CZ furnace 1 in which the single crystal silicon 6 is grown. The boundary part between the surface of the single crystal silicon 6 and a silicon melt 3 is recognized as a band-shaped ring 8 having a high brightness by said camera 7. The two points past the ring 8 are detected as high luminance points A, B by running the scanning line R of the camera 7 in the diametral direction of said ring 8. The intermediate point C of the points A, B is repeatedly detected and the displacement width of the point C within the specified time is converted to length. The length is recognized as the runout width of the single crystal silicon 6 in the furnace. The runout width of the single crystal silicon 6 in the CZ furnace 1 is thereby easily and quickly detected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for detecting swing amplitude of single crystal silicon in a CZ furnace, which is used to prevent swings of single crystal silicon in a CZ furnace.

゛ (Prior art and its problems) In recent years, the capacity of CZ furnaces has increased, and as a result, the wire method, which is less susceptible to the effects of microvibrations and can set the furnace height low, that is, the seeding via a jig, The most commonly used method is to suspend the device from the tip of a crystalline wire and raise the resulting single-crystal silicon while winding the wire.

However, in the above wire method, the rotation center of the wire (in other words, the rotation center of the single crystal silicon) and the rotation center of the crucible (
In other words, due to misalignment with the center of rotation of the silicone solution
The single crystal silicon tends to swing, which causes deterioration of the single crystal, and in the worst case, polycrystallization and shape deterioration (deformation) occur.

Therefore, it is necessary to manage the prevention of single crystal silicon in the CZ furnace, and for this purpose, a means for detecting the amplitude of fluctuation of single crystal silicon in the CZ furnace is required, but a simple and suitable means has not been proposed in the past. It wasn't.

In addition, as a method of measuring the swing width (width width) of an object, a method is generally used to process the image with a two-dimensional camera and calculate the displacement of the object's reference point (rotation center, etc. in the case of a rotating object). However, when applied to single-crystal silicon manufacturing equipment, the detection device would be large-scale, so conventional single-crystal silicon vibration amplitude detection devices using two-dimensional cameras have not been put to practical use.The present invention addresses the above-mentioned circumstances. It was done under

(Means for Solving the Problems) The present invention employs the following technical means to solve the above problems.

That is, two high brightness points are detected with a one-dimensional CCD camera placed facing inside the CZ furnace during single crystal growth, and the midpoint between the two high brightness points is repeatedly detected. The detection method involves converting the displacement width of a point into a length, and grasping the length as the fluctuation width of the single crystal silicon in the furnace.

(Invention foundation and data processing) Hereinafter, the present invention will be explained in detail based on the drawings.

Figure 1 is a schematic diagram of a CZ furnace during single crystal silicon growth.
1 is a CZ furnace chamber, 2 is a crucible that is rotatably arranged in the CZ furnace chamber 1, 3 is a silicon melt in the crucible 2, 4 is a wire hanging down toward the center of the 2, 5 is a seed crystal attached to the lower end of wire 4,
Reference numeral 6 indicates single crystal silicon that grows by adhering to the seed crystal 5.

When a CCD camera 7 is installed in a CZ furnace configured as described above, the boundary between the surface of the single crystal silicon 6 and the silicon melt 3 can be detected as a high brightness area. This is understood as a band-shaped ring 8 (hereinafter referred to as a fusion ring).

Therefore, when using a one-dimensional CCD camera that runs a scanning line R in the diametrical direction of this fusion ring 8, as shown in FIG. , B.

The present invention is realized by grasping the high brightness points A and B and performing the data processing shown in FIG. 3.

In other words, single-crystal silicon can be considered to be constantly oscillating, and there is a oscillation range at each point in time. Therefore, in the present invention, the amplitude is grasped as having one amplitude within a certain period of time, and this is corrected during actual operation.

For example, if there are two states shown in Figure 4 (one shown as a solid line and the other as an imaginary line), first, the respective midpoints C = a + b / 2, C' = a' + b' / 2 The amplitude of fluctuation is calculated from these values. Specifically, within a certain period of time, c, c', c''-...
Find the Max - Min of these numbers, multiply this by the length conversion constant K, and get L = (Max - Min )
Find X K, further take into account the roundness correction amount C (L-C
) is the amplitude.

(Example) A one-dimensional CCD is installed in a single-crystal silicon manufacturing equipment equipped with a crucible.
Install the camera and check the voltage of each element in this camera A/D
The brightness distribution is imported into the scale of the microcomputer via the conversion interface, and from the brightness distribution data imported into the scale, intermediate points C are determined every 0.5 seconds, 20 intermediate points are counted as 10 points, and the above data processing is performed. As a result, we were able to monitor and correct the vibration amplitude on a constant basis, and also to prevent quality deterioration (polycrystalization) and shape deterioration (deformation). It was confirmed that the loss was reduced and the yield of single crystal silicon production was improved by 5% compared to the conventional method.

(Effects of the Invention) As explained above, 1. Since the present invention is a method for detecting the amplitude of fluctuation of single crystal silicon using a -dimensional CCD camera, the device is small and suitable for practical use, and only one device can be used. The invention allows rapid correction of runout in single-crystal silicon, resulting in improved quality. It also has the advantage that it can be used to create an index of furnace accuracy (displacement between the wire core and the crucible core).

[Brief explanation of the drawing]

Figure 1 shows a schematic diagram of the CZ furnace, Figure 2 (1) is an explanatory diagram of the body fusion ring, Figure 2 (2) shows the brightness distribution of the fusion ring as seen with a -dimensional CCD camera, and Figure 3 shows the main body fusion ring. The flowchart of the invention, FIG. 4, is an explanatory diagram of how to take the intermediate point. 6...Single crystal silicon 7-CCD camera A, B...High brightness point patent applicant Kyushu Electronic Metals Co., Ltd. Patent applicant Osaka Titanium Manufacturing Co., Ltd. Agent Patent attorney Masazumi Mori Figure 1 6 Axis Car crystal silicon 7-CCD camera A, B-axis high brightness point

Claims (1)

[Claims] One-dimensional CCD placed towards the inside of the CZ furnace during single crystal growth
Grasp two high-brightness points with a camera, repeatedly detect the midpoint between the two high-brightness points, convert the displacement width of the midpoint within a certain period of time into a length, and convert the length into a single crystal in the furnace. A method for detecting swing width of single crystal silicon in a CZ furnace, characterized by detecting the swing width of silicon.